What the Anesthesiologist Should Know before the Operative Procedure

Pulmonary resections are just one of the possible categories of thoracic surgical procedures. Amongst others, thoracoscopic and thoracotomy procedures are performed for: esophageal diseases, pericardial diagnostic and therapeutic procedures, pleural biopsies and diverse pleural resections, mediastinal masses biopsy / resection, thymectomy, sympathectomy and neurolytic procedures, diaphragm plication, chylothorax intervention, and lung volume reduction surgery. However, lung parenchyma resections are probably the most common procedures. The primary reason is the increased incidence and early detection of lung cancer. As such, pulmonary resection procedures are most likely related to diagnosis and treatment of possible malignancy. Otherwise, differential diagnosis of benign diseases is less common. Of note, surgical resection is the only curative modality in lung cancer.

Lung resection procedures include; wedge resection for nodulectomy, metastasectomy, segmentectomy, lobectomy and pneumonectomy. These procedures can be performed via standard (thoracotomy) or thoracoscopic procedures. The last category includes video-assisted thoracoscopic surgery (VATS). In general, thoracoscopic / video-assisted and minimally-invasive approaches are being considered of choice in most cases given the shown advantages in terms of enhanced recovery, decreased length of stay and particularly due to the possibliity of sparing mechanical chest wall function when compared to thoracotomy procedures.

The type of surgical procedure and extent of the pulmonary resection are not the only significant considerations when approaching this patient population. However, these factors dictate many of the technical considerations and the anesthetic management of pulmonary resection patients. In particular, regardless of the extent of pulmonary resection, total collapse of the operative lung is essential for the safe conduct of thoracoscopic and VATS procedures. Otherwise, it can be expected that the risk of postoperative respiratory complications and gas exchange impairment is increased during more extensive parenchymal resections, such as lobectomy and pneumonectomy.

Importantly, beyond the surgical approach and extension of lung resection there are several risk factors that have to be considered at any time during decision-making and management of these patients. The factors more related with overall incidence of complications are: male gender, preoperative oxygen dependence, and pack-year smoking history. Other associated risk factors include: age ( > 70 years old), amount of lung resected, preoperative baseline lung function, presence of pulmonary fibrosis, preoperative chemotherapy, and additional comorbities. Therefore, it is the overall assessment of the patient and procedure, more than the approach (standard vs. thoracotomy), or the type of resection (wedge vs pneumonectomy) which will determine the risks and management strategy in every individual case.

Regardless of the procedure, the goals for anesthetic management of patients for pulmonary resections are to achieve optimal pain control, minimal mechanical respiratory disturbance in an extubated patient, breathing spontaneously and coughing freely at the end of the procedure. Of course, the safe conduct of a quality anesthetic must facilitate the surgical procedure and exposure.

1. What is the urgency of the surgery?

What is the risk of delay in order to obtain additional preoperative information?

Pulmonary Resections: In general pulmonary resections are largely elective procedures. Whenever a lung resection is performed in an urgent or emergent fashion, there is significant risk of morbidity and mortality added to the procedure.

Pneumonectomy with purpose of treating lung malignancy is an elective procedure. It should be performed after careful assessment of the extension and resectability of the tumor, determination of the baseline cardiopulmonary status, and evaluation of the possible physiologic postoperative impact. There should also be an evaluation of comorbities and their possible implications. Nonetheless, the procedure should be performed promptly, usually not more than 3 months after diagnosis. Any delay exposes the patient to further cancer extension in the interval.

Emergent- Pulmonary resections are rarely emergent procedures. The most significant exception is massive hemoptysis. Lung resection in this situation is considered only with other measures have failed and the patient is a life-threatening situation. Likewise, very rarely a pneumonectomy is an emergent procedure.
Urgent- In some instances a lung resection and / or pneumonectomy can be considered semi-urgent when it is intended to provide source control for a severe sepsis/septic shock such in patients with lung abscesses and / or bronchiectasis. The urgent performance will significantly increase the associated morbidity and mortality.
Elective- Lung resection or pneumonectomy for treatment of lung carcinoma are always elective procedures after complete preoperative assessment and patient optimization.

2. Preoperative evaluation

The cardiopulmonary status of the patient is the main determinant of outcome and the central part of the preoperative assessment, independently of the type of approach or resection proposed. The respiratory function can be evaluated in three independent but related areas: respiratory mechanics, gas exchange and cardiorespiratory interaction. The most widely used test of respiratory mechanics is FEV₁ (Forced Expiratory Volume in 1 second). The most useful test of gas exchange is the determination of diffusing capacity for carbon monoxide (DLCO). Most importantly, the respiratory function should be assessed in light of cardiopulmonary interaction. In this sense, the primary determinant of outcome is exercise tolerance. Stairs climbing is traditionally used to screen in this last area.

Not every patient needs complete assessment of pulmonary function tests and gas exchange. The decision should be made taking into consideration the baseline clinical status of the patient and the expected impact of the planned operation. In general, preoperative evaluation is more extensive for lobectomy or pneumonectomy as well as in patients with poor baseline cardiopulmonary function.

Patients should be evaluated following the American Heart Association / American College of Cardiology (AHA/ACC) Guidelines for patients with cardiac disease for non-cardiac surgery. Although these guidelines consider thoracotomy to be an intermediate-risk procedure for cardiac complications, pneumonectomy should be considered a high-risk surgical procedure category, particularly in the elderly. Otherwise, lobectomy or less extensive pulmonary resections could be considered intermediate or even high-risk in particular circumstances or patients. Likewise, most patients will have significant clinical risk factors given the high incidence of comorbidities.

All patients with active cardiac conditions should have evaluation and treatment before attempting any lung resection or pneumonectomy. Due to a decreased functional capacity, many patients will have an extensive assessment for possible myocardial ischemia and ventricular function, in order to stratify risk and to evaluate tolerability of the planned lung resection or pneumonectomy. Patients with severely decreased pulmonary function should have formal cardiopulmonary exercise testing to accurately evaluate functional ability by determining VO₂ Max (maximum oxygen consumption). This enables the providers to differentiate lung function impairment from heart failure as the cause of their functional compromise, and to physiologically define their ability to tolerate lung resection. In patients with borderline decreased lung function who are scheduled for extensive lung resection, cardiopulmonary exercise testing with determination of VO₂ may be necessary to accurately define their predicted postoperative lung function, and hence their ability to physiologically tolerate lobectomy or pneumonectomy.

All patients should undergo pulmonary function test / spirometry (including FEV₁) and determination of DLCO to assess their baseline and to determine risk. Afterwards, some patients will require ventilation / perfusion nuclear scans to accurately predict or calculate postoperative pulmonary function.

Medically unstable conditions warranting further evaluation include: Recent MI (< 30 days), unstable of severe angina, acute or decompensated heart failure, severe valvular disease (severe aortic and/or mitral stenosis), and significant arrhythmias (high degree AV block, symptomatic bradyarrhythmias, ventricular and supraventricular arrhythmias). Active infection/sepsis of any source as well as DVT and/or PE should also be treated first.
Delaying surgery may be indicated if: There is COPD exacerbation, active tracheobronchial or pulmonary infection until treatment is initiated and patient is clinically stable. Sepsis /septic shock from any cause until treatment has started and there has been adequate resuscitation. Untreated DVT and/or hemodynamically significant PE until extension assessed and treatment started. It may require IVC filter placement.

3. What are the implications of co-existing disease on perioperative care?

b. Cardiovascular system

Perioperative evaluation

Acute/unstable conditions: Regardless of the planned approach or extension of pulmonary resection, patients after MI should not have elective surgery until 4-6 weeks after the event given the increased mortality and increased incidence of perioperative cardiac events. Patients with signs and symptoms, or echocardiographic evidence of heart failure, should have medical optimization before surgery. Patients can undergo right heart catheterization with hemodynamic evaluation in order to assess the severity of the heart failure and to clarify diagnosis if necessary. The presence of severe symptomatic aortic or mitral stenosis may necessitate valve replacement. In many cases, the patient’s condition may preclude the latter and should only have medical optimization. Otherwise, the time required for valve replacement may render the patient inoperable due to cancer extension. Significant or unstable arrhythmias diagnosed by ECG or Holter monitoring should be treated as necessary. It may require temporary pacemaker or defibrillator placement.

Baseline coronary artery disease or cardiac dysfunction – Goals of management: The incidence of perioperative myocardial ischemia during lung surgery has been reported at nearly 4%. The incidence of perioperative ischemia and MI is much higher in patients with a prior MI, with an increased incidence of morbidity and early mortality (the latter up to ~20%). If suggested by clinical history and/or ECG, the presence of myocardial ischemia can be assessed by Exercise ECG Testing (the ischemic threshold is also useful for anesthetic management). If the patient is unable to exercise, pharmacologic stress testing with dobutamine stress echocardiography (DSE), or dipyridamole or adenosine nuclear imaging can be performed. In patients with COPD, DSE is preferred because adenosine and dipyridamole can cause bronchospasm. The presence of severe myocardial ischemia during non-invasive tests requires left heart catheterization / coronary angiography.

Perioperative risk reduction strategies: PCI and CABG are not recommended with the sole purpose of reducing perioperative cardiac risk. These procedures are considered if indicated regardless of the planned pulmonary resection or pneumonectomy. Patients after CABG have a lower incidence of MI and death after major thoracic surgery than medically treated patients. Nonetheless, it is recommended that lung surgery should be delayed 4-6 weeks after CABG. Otherwise, regarding PCI, if a patient requires a pulmonary resection within 2 months, a bare metal stent (BMS) should be implanted instead of a drug-eluting stent (DES). Beta-blockers should be continued as part of a medical regimen and in patients diagnosed with CAD. They should also be given to patients with diagnosed myocardial ischemia during stress testing and considered at risk. Otherwise, starting beta-blockers acutely without proper titration may increase the risk of hypotension, stroke and death perioperatively. The use of alpha-agonists such as clonidine may be beneficial in patients who have contraindications to beta-blockers. In general, in patients with high-risk for perioperative ischemia it is important to maximize the balance of myocardial oxygen delivery / consumption with particular emphasis on heart rate control, stable coronary perfusion pressure, management of hypoxemia and optimizing oxygen-carrying capacity.

Right Ventricular Dysfunction during Pulmonary Resection: Pneumonectomy can have significant effects on right ventricular function with immediate increase in right ventricular afterload due to increased pulmonary vascular resistance and pulmonary artery pressure after manipulation and clamping of the pulmonary artery. These effects can cause important intra- and postoperative right ventricular dysfunction. This event is more pronounced after the first postoperative day but can be significant even after 4-7 days. In some cases, it can be persistent. Other major pulmonary resections such as lobectomy, can occasionally cause transient increases in pulmonary vascular resistance and pulmonary artery pressures but the effects on the right ventricle afterload are generally well-tolerated and rapidly resolve, unless the patient have baseline pulmonary hypertension and/or right ventricular dysfunction. Patients at baseline high-risk, or a high level of suspicion should undergo TTE to assess for pulmonary hypertension and right ventricular dysfunction preoperatively. Right heart catheterization may be indicated in some cases. Although, intraoperative use of TEE is done routinely during lung transplantation only, TEE may be useful during pneumonectomy or pulmonary resection in cases of suspected right ventricular dysfunction or myocardial ischemia. This is applicable as well as in cases of unresponsive hemodynamic instability of unclear etiology.

c. Pulmonary

Pulmonary complications are the main cause of morbidity and mortality in patients undergoing pulmonary resection and especially pneumonectomy. The incidence of postoperative pulmonary complications is directly and primarily related to the degree of baseline pulmonary dysfunction, and to the amount of lung tissue removed. Other significant factor is the alteration of chest wall mechanics as consequence of thoracotomy. The degree of alteration is more pronounced with more extensive thoracotomy incisions. Thus, Video-Assisted Thoracoscopic Surgery (VATS) is now a widely accepted approach for most thoracic procedures (including lung resections, even pneumonectomy), because of the decreased postoperative impairment in pulmonary function, better patient acceptance, lower pain scores and faster return to baseline level of activity. However, it is important to realize that postoperative pain after VATS procedures is unpredictable, and may reflect visceral, pleural and diaphragmatic components. Even with less chest wall injury, VATS procedures can be a cause of respiratory dysfunction and mechanical respiratory due to pain.

COPD:

Perioperative evaluation: The clinical history will determine the presence and severity of symptoms which in turn have prognostic implications. There should be an assessment of the presence of COPD and/or interstitial lung disease. Most patients requiring pulmonary resection (for lung cancer) have significant degrees of COPD due to tobacco smoking. The duration, severity of COPD, frequency of exacerbations, and smoking status should be determined as well. All patients considered for lung resection should undergo spirometry. If FEV₁ (Forced Expiratory Volume in 1 second) is > 60 % of predicted value or > 2 L, patients are suitable for pulmonary resection included pneumonectomy without further evaluation. Patients with evidence of interstitial lung disease on radiological tests or dyspnea on exertion should also have DLCO measured even with adequate FEV₁. In patients with FEV₁ and DLCO < 60 % predicted, the postoperative lung function should be predicted based on quantitative ventilation/perfusion lung scan. If the calculated predicted postoperative FEV₁ and DLCO (FEV₁-ppo and DLCO-ppo, respectively) are < 40%, patients should undergo Cardiopulmonary exercise testing. Pneumonectomy in particular is considered high-risk if VO₂ Max is < 15 mL/kg/min.

Perioperative risk reduction strategies: After the decision to proceed to pulmonary resection has been finalized, medical therapy should then be optimized. Treatment with a combination of long- and short-acting bronchodilators should be implemented. It is important to treat any active airway infection before proceeding. COPD patients and those with pulmonary dysfunction awaiting any pulmonary resection surgery will benefit from pre- and perioperative chest physiotherapy. This will prevent secretions retention and atelectasis. Otherwise, early physiotherapy will improve exercise tolerance and mobility. Thus, in high-risk patients it may prevent difficult weaning from mechanical ventilation if required, and decrease the possibility of ventilator-dependency postoperatively, particularly after pneumonectomy.

Reactive airway disease (Asthma):

Perioperative evaluation: If the diagnosis of Asthma is not clear from clinical history, a clue of its presence may be given by the reversibility of airway obstruction in the PFTs after bronchodilator administration.

Perioperative risk reduction strategies: The patient should be taken in optimal condition with no or minimal airway inflammation and PEF (Peak Expiratory Flow) > 80 % of patient’s asymptomatic baseline. A stable regimen of short-acting bronchodilators and corticosteroids should be continued until the day of surgery. In symptomatic patients on an optimized / stable treatment, a short-term (3-4 weeks) course of oral prednisone 40 mg/day is effective and safe.

Smoking: There is a significant increase in associated morbidity and mortality in smoker patients for any thoracic surgery. The risk is directly proportional to the pack/year history and inversely proportional to the time since last use. Therefore, most studies suggest that in order to reduce the incidence of postoperative pulmonary complications patients should stop smoking at least 8 weeks before surgery. Short-term benefits of smoking cessation are decreased levels of carboxyhemoglobin and less hypoxemia, which are evident from 12-24 hours of smoking cessation. Smoking cessation is beneficial for patients undergoing pulmonary resection at any point before surgery. Smoking up to the time of surgery is associated with much poorer prognosis when compared with recent cessation or former smokers.

d. Renal-GI:

Renal

Given the strong association between lung cancer and smoking, as well as between smoking and atherosclerosis / cardiovascular disease; there is high probability of hypertension and chronic kidney disease (CKD) in this population. This is also complicated by advanced age. The CKD related with atherosclerosis can be further compounded by diabetic nephropathy. Patients undergoing pulmonary resection, especially pneumonectomy are at risk of AKI (Acute Kidney Injury) due multiple factors including: Perioperative hemodynamic instability (with hypotension and/or decreased renal perfusion pressure), altered venous return with intravascular volume status changes, hypovolemia and fluid shifts, systemic inflammatory response syndrome triggered by ALI (acute lung injury), and the neuroendocrine / metabolic response to surgery.

Perioperative evaluation: The presence of CKD and/or significant risk factors for AKI added to the high-risk nature of pneumonectomy, or similarly to major pulmonary resection can make this patient group highly susceptible to perioperative AKI. Calculated GRF is a good indicator of baseline renal function. Otherwise, a determination of the baseline intravascular volume status, hemoglobin/hematocrit, and complete metabolic panel will provide a baseline for other interventions. There is no advantage to further testing. No biomarkers have been validated in this patient population.

Perioperative risk reductions strategies: Maintenance of preoperative normovolemia in patients at risk will decrease the incidence of AKI. Patients with chronic anemia have an increased risk of AKI. Avoid further insult of acute on chronic anemia in this population. Try to correct hypotension and vasodilation from any sources. Use vasopressors in order to keep appropriate renal perfusion pressures. Use transfusion of blood products if necessary. Abstain from using any nephrotoxic agents if possible.

Patients with lung cancer have a high incidence of hypoalbuminemia and malnutrition. Low albumin levels have been associated with increased mortality in high-risk surgical patients. Otherwise, hypoalbuminemia can increase the free active plasmatic fraction of many medications, altering their pharmacokinetics and making their phamacodynamic response less predictable. This is particularly applicable to sedatives and anesthetic medications.

Perioperative evaluation: Patients can have gastroesophageal reflux disease (GERD) and/or hiatal hernia. Assess for symptoms and their severity. Evaluate the response to current treatment to determine the risk of perioperative pulmonary aspiration. Liver function tests and albumin levels are part of the preoperative evaluation of the cancer patient.

Perioperative risk reduction strategies: Continue treatment for GERD until the day of surgery. Consider administration of an intravenous H₂-blocker and a prokinetic to patients with poorly controlled reflux symptoms and no chronic treatment. Carefully titrate small doses of sedative and anesthetic medications to clinical response in patients with hypoalbuminemia or malnutrition. Expect longer duration of action of medications in these patients when compared with non-hypoalbuminemic patients.

e. Neurologic:

Cerebral metastatic disease secondary to lung cancer is a contraindication for pneumonectomy. Otherwise patients with cerebral metastatic disease can present for less extensive pulmonary resection, most probably with diagnostic purposes. Certain paraneoplastic syndromes of lung malignancies have neurologic manifestations. The most common are central and peripheral neuropathies caused by autoantibodies and manifested by weakness and neurological disability. Otherwise, Lambert-Eaton syndrome (Myasthenia-like syndrome) is produced by autoantibodies against presynaptic voltage-gated calcium channels resulting in proximal muscle weakness.

Acute issues: Any acute neurologic deficits should be investigated to rule out cerebral metastasis. If metastatic disease is absent, paraneoplastic syndromes should be diagnosed and controlled before pulmonary resection surgery if possible. Otherwise, severe and/or symptomatic cerebrovascular disease is highly prevalent in smokers and should be suspected whenever there are focal or global neurologic symptoms. Diagnosis and management of acutely symptomatic carotid artery disease should be done before pulmonary resection.

Chronic disease: Patients with carotid artery disease require estimation of the severity in order to establish an appropriate perioperative management plan.

Perioperative evaluation: After careful clinical history and physical exam reveal the presence of global and/or focal neurologic symptoms, CT and/or MRI should be performed to rule out cerebral metastasis. Peripheral deficits and muscle weakness indicate possible paraneoplastic syndromes. It is useful to rule out metabolic derangements such as hyponatremia, and to determine the presence of antibodies. Carotid ultrasound is the screening test of choice for carotid artery disease.

Perioperative reduction strategies: In many cases, tumor removal or chemo/radiotherapy is the only effective treatment for paraneoplastic syndromes. These syndromes may complicate perioperative management as they can delay extubation and can also predispose to respiratory complications. Lambert-Eaton syndrome can require immunosuppression with azathioprine and/or prednisone, and even plasma exchange.

f. Endocrine:

Poorly controlled diabetes is associated with increased incidence of surgical site infections and delayed wound healing. Adequate blood glucose control may provide benefit. There are no other specifically described morbidity/mortality benefits of strict glucose control in this particular population. Blood glucose management benefits have been extrapolated from cardiac surgical patients to other major surgery populations.

g. Additional systems/conditions which may be of concern in a patient undergoing this procedure and are relevant for the aesthetic plan (eg. Musculoskeletal in orthopedic procedures, hematologic in a cancer patient)

As with all malignancies, patients with lung cancer are at increased risk of venous thromboembolism especially with high burden / size tumors. This risk is greater in smokers, in whom it is directly proportional to packs/ year history. The highest risk of venous thromboembolism is in patients for pneumonectomy. Additionally, this risk is compounded in the perioperative period by the injury and hypercoagulability in a way that the risk increases with the complexity of the pulmonary resection procedure. The occurrence of DVT / PE in the perioperative period greatly increases the morbidity and mortality, both at short- and long-term. These patients should have pre- and postoperative venous thromboembolism pharmacologic and mechanical prophylaxis.

Any signs or symptoms suspicious of DVT / PE should prompt screening with bilateral upper and/or lower extremities Doppler ultrasound. The presence of PE should be confirmed with spiral chest CT. After a confirmed diagnosis of DVT and/or PE, full therapeutic intravenous heparin infusion should be started. DVT treatment should be stopped only 4-6 hours before surgery to avoid increased surgical bleeding and re-started as soon as considered safe by the surgeon. In many instances, depending on the risk, patients should have an IVC filter placed before lung resection or pneumonectomy. Early postoperative ambulation will also decrease the risk of postoperative DVT and is essential in this patient population.

4. What are the patient's medications and how should they be managed in the perioperative period?

N/A

h. Are there medications commonly seen in patients undergoing this procedure and for which should there be greater concern?

Cardiac:

Beta blockers: Chronic administration of beta blockers should be continued perioperatively given the possible reduction of perioperative cardiac complications. The administration of beta blockers in the perioperative period is of clear benefit in high-risk surgical patients. Initiation of beta blockers acutely during the perioperative period can also increase the incidence of hypotension and stroke. This has been associated with an increased risk in perioperative mortality. Given the high incidence of COPD and airway reactivity in this population, many patients can have bronchospasm with beta blockers.

Statins: Patients receiving statins should continue them perioperatively. Studies of patients undergoing cardiac surgery on statins preoperatively had shown reductions in mortality, stroke, and atrial fibrillation. Statin therapy may have widespread effects in diverse surgical populations given the reduction of Systemic Inflammatory Response Syndrome (SIRS).

Anti-platelet agents: Patients can be on aspirin and clopidogrel (IIB/IIIA platelet receptor inhibitor) after coronary stent placement. The risk of increased surgical bleeding should be balanced against the possibility of acute in-stent thrombosis and perioperative myocardial infarction. In general, patients should receive at least 4-6 weeks of uninterrupted aspirin and clopidogrel therapy after BMS placement, and ideally one year after DES placement. A factor to consider is the anticipated need to insert an epidural catheter for postoperative analgesia. Epidural analgesia decreases significantly the risk of pulmonary complications and improves postoperative respiratory function. With this decision, there should be a consensus between the surgeon, the cardiologist and the anesthesiologist. Regardless the final decision, the antiplatelet medications should be started as soon as possible after lung resection surgery. Patients at high risk for in-stent thrombosis and perioperative myocardial infarction and death are those with multiple stents, high-risk coronary lesions, recent stent placement and CKD. Aspirin can be continued whenever an epidural catheter is placed (or removed). Clopidogrel should be stopped 7-10 days before epidural placement in order to decrease the possibility of epidural and/or spinal hematoma. In patients at high-risk of in-stent thombosis clopidogrel can be stopped 4-5 days before surgery and intravenous eptifibatide started 24 hours before surgery and re-started as soon as possible postoperatively in order to “bridge” them in the perioperative period. This special protocol devised to provide protection against in-stent thrombosis can allow these patients to receive the beneficial effects of epidural analgesia at the same time. The residual antiplatelet effects of clopidogrel can be assessed by platelet functional tests in order to decide exactly when to safely place or remove an epidural catheter.

Pulmonary:

Perioperative bronchodilators can control bronchospasm and improve respiratory mechanics. As part of a preoperative chest / physiotherapy program these medications can help to reduce perioperative respiratory complications. Pharmacotherapy for management of chronic respiratory conditions should be continued perioperatively, including inhaled and oral steroids, as well as mast cell stabilizers and leukotriene inhibitors for chronic asthma therapy.

Renal:

Diuretics are used as adjuvant therapy for hypertension and/or chronic heart failure. Typically, diuretics are discontinued perioperatively given the possibility of dehydration / hypovolemia. Diuretic therapy can also increase the possibility of perioperative AKI. These medications should be used intra- and perioperatively on an individual basis.

i. What should be recommended with regard to continuation of medications taken chronically?

Cardiac: See above.

Pulmonary: See above.

Renal: See above.

Neurologic: See above regarding antiplatelet therapy for carotid artery disease. Medications for seizure control should be continued perioperatively. Beware of the pharmacokinetic implications of chronic use of anticonvulsants in the metabolism of other medications, particularly of neuromuscular blockers. Due to the increased metabolism of neuromuscular blockers in this situation, their dosage may need to be increased and/or their interval of administration should be shortened. The use of peripheral nerve stimulator monitoring is advised.

Anti-platelet: See above.

Psychiatric: Continue medications for depression and anxiety preoperatively. They should be started as soon as possible in the postoperative period.

j. How To modify care for patients with known allergies –

Besides the exposure to antibiotics and/or latex products, the other particular concern during pulmonary resection and pneumonectomy is the use of local anesthetics for epidural analgesia. There are antibiotics of choice for patients with known allergies (discussed below). Local anesthetic allergy is very uncommon. Most cases are incorrectly labeled as allergies when intravascular absorption of local anesthetic causes hypotension and/or neurologic symptoms. Similarly, the intravascular injection of local anesthetics with epinephrine can cause symptomatic tachycardia and hypertension.

k. Latex allergy- If the patient has a sensitivity to latex (eg. rash from gloves, underwear, etc.) versus anaphylactic reaction, prepare the operating room with latex-free products.

Every institution has a latex allergy protocol that should be activated as early as possible. All members of the team from preoperative admission to all areas of postoperative care should be alerted of this situation. Of particular importance, although uncommonly used for pulmonary resection surgery, use a latex-free pulmonary artery catheter if the patient has a known latex allergy.

l. Does the patient have any antibiotic allergies? (common antibiotic allergies and alternative antibiotics)

Discussed below.

m. Does the patient have a history of allergy to anesthesia?

Malignant hyperthermia:

Documented- avoid all trigger agents such as succinylcholine and inhalational agents:

Proposed general anesthetic plan:

[- MH protocol]
Family history or risk factors for MH:

5. What laboratory tests should be obtained and has everything been reviewed?

Pulmonary resection surgeries are usually performed commonly in patients with significant respiratory function compromise, and also with multiple comorbities, which requires a comprehensive preoperative assessment. In particular, pneumonectomy is an elective high-risk surgical procedure that requires a thorough multiorgan system evaluation.

Common laboratory normal values will be same for all procedures, with a difference by age and gender.

Hemoglobin levels: Most patients with lung cancer or in chemo/radiotherapy will have chronic anemia. Some patients with advanced lung disease and chronic hypoxemia will have polycythemia. The blood loss for standard and/or thoracoscopic pulmonary resection including pneumonectomy is usually well tolerated. Extrapleural pneumonectomy is a more extensive procedure with increased blood loss and hemodynamic instability that is more likely to require blood products transfusion.

Electrolytes: Patients with lung cancer can have extensive metabolic alterations mostly related with paraneoplastic syndromes which can include hyponatremia, hypercalcemia, Cushing’s syndrome and Lambert-Eaton syndrome. Renal impairment due to advanced age, atherosclerosis, cardiovascular disease and heart failure is highly prominent in this population. Electrolyte abnormalities are also compounded by diuretic therapy. It is important to assess preoperatively, in particular sodium, potassium and magnesium given the high incidence of arrhythmias intra- and postoperatively. Electrolytes are also helpful to assess hydration / intravascular volume status.

Coagulation panel: Any coagulation abnormalities should be diagnosed preoperatively given the risk of significant surgical bleeding, and frequently the need to place an epidural catheter. Platelet count, PT/INR and PTT are required. In some instances, platelet functional assays are useful in patients with antiplatelet therapy in order to further assess the potential bleeding risk and safety of epidural catheter placement.

Imaging: Chest X-ray is indicated to evaluate the trachea and proximal airways, and to assess possible difficulty for endobronchial intubation / lung isolation (mass effects, deviation, compression and obstruction). Likewise, chest CT imaging will provide further and more detailed information of distal airway problems not evident in X-ray. The presence and location of masses, the extent of lung parenchymal disease, atelectasis or post-obstructive lung collapse are predictive of airway problems and hypoxemia during single lung ventilation.

Other tests: BUN and creatinine will help to assess hydration / intravascular volume status, and to determine renal risk. Additionally, some chemotherapeutic agents can have nephrotoxic effects. Calculation of GFR will permit risk stratification by determining the presence of CKD and its staging. Thus, the risk of AKI can be better established. Determination of GFR is also useful to choose and to adjust medications doses accordingly. Liver function tests are helpful to determine anesthetic choices and medication dosages based upon the possibility of metabolic and pharmacokinetic alterations. In particular, albumin level is an overall indicator of chronic nutritional status and it also has value as a predictor of perioperative morbidity and mortality.

Intraoperative Management: What are the options for anesthetic management and how to determine the best technique?

For modern anesthetic practice, pulmonary resections and pneumonectomies are performed under general anesthesia with endotracheal intubation and operative lung isolation. Selective collapse of the operative lung is absolutely necessary for optimal surgical exposure and safe conduct of surgery during thoracoscopic / VATS or minimally invasive techniques.

The main objective is to devise an anesthetic technique that allows prompt postoperative extubation (ideally in the OR). In most cases, the technique of choice should be supplemented by preoperative placement of a thoracic epidural catheter and perioperative epidural analgesia, if not contraindicated. In the event of epidural contraindication, other regional / local anesthetic techniques can be used as alternatives to provide optimal perioperative pain control.

Importantly, the anesthetic technique and the decision to perform an epidural should be made upon the potential reduction of perioperative complications and not solely upon the surgical approach or planned procedure. Therefore, baseline pulmonary status and risk of complications should dictate the final decision for anesthetic approach. For example, an elderly patient with very poor lung function will benefit from a short-acting agents total intravenous anesthesia supplemented by a continuous thoracic epidural placed and activated preoperatively, whereas a patient with no comorbidities, normal baseline lung function, and undergoing a peripheral wedge resection probably no further benefit from an epidural vs. systemic analgesia, also different anesthetic techniques would have comparable results.

In any case, an aggressive postoperative pain management plan should be established and implemented in the preoperative period.

a. Regional anesthesia – Pure regional anesthetic techniques are not indicated for pulmonary resection. The extension of the procedure (comprising wide level of both, somatic and visceral innervations), as well as the requirement of single lung ventilation are the main reasons for requirement of general anesthesia. Thoracic epidural anesthesia as a sole anesthetic technique can be used only during procedures on structures with limited innervation in the thorax.

Neuraxial: The adjuvant use of an epidural analgesic technique should be considered in many instances. Thoracic epidural catheter placement (T3-7) with a combination of low concentration of local anesthetics and opioids is the most advantageous technique. Although, the use of a lumbar epidural catheter may provide limited benefit by injection of opiods, the synergist effects of the local anesthetic / opioid combination are not possible. Otherwise, the use of spinal / intrathecal opioids is an alternative, provided the known risk of delayed respiratory depression.

Benefits:

Improved postoperative respiratory mechanics (increased tidal volume, FRC, and decreased lung resistance).

Decreased postoperative pain scores with earlier and better ability to cough. Decreased use of systemic opioids. Better postoperative analgesia with movement.

Decreased incidence of respiratory complications.

Decreased incidence of cardiac arrhythmias due to decreased sympathetic stimulation.

Decreased incidence of perioperative myocardial ischemia due to improved oxygen supply / demand balance.

Earlier mobilization and facilitation of chest / physical therapy.

Decreased disturbance to GI function when compared with general anesthesia.

Decreased neuroendocrine response to surgical stress.

Potential decrease in surgical blood loss due to vasodilation and blood flow redistribution.

Drawbacks:

Technique related adverse effects such as, dural puncture, radicular nerve injury, epidural vein perforation, spinal cord injury, and epidural / spinal hematoma.

Hypotension due to sympathetic blockade and peripheral vasodilation.

Bradycardia due to high thoracic sympathetic blockade (with vagal preponderance).

Limb muscle weakness due to motor blockade.

Potential to decrease inspiratory effort with high levels of motor blockade.

Opioid-related side effects. The most important is respiratory depression. Other opioid effects include sedation, nausea, vomiting, pruritus and ileus.

Contraindicated in patients with coagulopathy or in patients on therapeutic doses of anticoagulants or antiplatelet agents. ASRA guidelines should be followed. This is the case of patients on treatment for DVT/PE or in patients being treated with antiplatelet agents for coronary stents or peripheral arterial vascular disease. In these situations, epidural placement should be considered individually against the risk of temporarily stopping those medications.

Issues:

The decision to use an epidural technique should involve the surgical team, and requires the participation of a dedicated pain management team in order to optimize treatment, and to decrease the incidence of complications.

The timing and dosages of anticoagulant and antiplatelet therapies should be planned accordingly with the surgical team during the preoperative evaluation following existing guidelines and institutional protocols.

Peripheral Nerve Block: Other regional anesthesia techniques include, thoracic paravertebral blocks, intercostal nerve blocks, and sometimes interpleural analgesia.

Benefits: Thoracic paravertebral analgesia via catheter as part of a multimodal analgesia regimen is an alternative to thoracic epidural analgesia with similar analgesic effects.

The catheter insertion can be performed using a preoperative percutaneous technique or an open approach via the surgical incision.

Decreased incidence of hypotension and hemodynamic instability due to limited and unilateral sympathetic blockade.

Decreased risk of spinal cord injury and epidural / spinal hematoma. Thoracic paravertebral blockade can be performed in patients receiving prophylactic anticoagulation without an increased risk of complications. Thus, avoids many of the issues of epidural catheter placement.

Drawbacks:

High failure rate even in experienced hands (6-10%). Learning to perform the technique requires a high volume of procedures.

Requires the use of high concentration of local anesthetics, increasing the incidence of toxicity due to rich vascularization and systemic absorption.

Opioids are not synergistic to local anesthetics at this level. They will have systemic effect only.

Low risk of pneumothorax and lung injury. There is also risk of vascular injury with bleeding and hematoma formation.

Issues: Intercostal nerve blocks are of limited utility given the need to perform repeated injections every 6-8 hours. Catheter techniques are not very reliable due to difficulty in maintaining the catheter in place. Similarly, there is high-risk of local anesthetic toxicity because the intercostal space is the place with the highest systemic absorption level. Interpleural analgesia is generally not used because inconsistent effects, loss of local anesthetic thorough the chest tubes, random spread across the pleural space, and pooling in dependent areas of the chest.

b. General Anesthesia

The main goal of any anesthetic technique for pulmonary resection surgery including pneumonectomy, is to provide the earliest possible extubation with expedited return of spontaneous ventilation and the best possible respiratory mechanics. Thus, a patient with minimal alteration of sensorium and ability to protect the airway is ideal.

Benefits:

Ability to conduct controlled mechanical ventilation to optimize gas exchange and alveolar ventilation.

Provides a motionless surgical field by allowing proper surgical lung isolation and collapse.

Optimal surgical positioning and patient protection.

Provides optimal conditions and patient comfort to perform invasive monitoring and vascular access.
Drawbacks:

Depressed postoperative respiratory drive and unfavorable respiratory mechanics. It may contribute to further postoperative hypoxemia and hypercarbia.

Decreased ability to protect the airway with increased postoperative risk of airway obstruction contributing to impaired gas exchange.

Residual anesthetic effects increase the possibility of postoperative pulmonary aspiration in patients at high-risk.

Possible increase in postoperative cognitive dysfunction in elderly patients.
Other issues: The multiple organ dysfunction and metabolic alterations in patients with cancer can cause changes in pharmacokinetics and pharmacodynamics of multiple drugs that will modify the individual response to general anesthesia.
Airway concerns- The presence of difficult airway can make provision of lung isolation more challenging. It can also have implications during extubation and postoperative care. Moreover, extensive airway manipulation can cause postoperative airway edema with increased risk of losing the airway due to obstruction post-extubation. In such cases, it is convenient to leave the ETT in place and to extubate when the edema has resolved. Since double-lumen endotracheal tubes (DLTs) have larger diameters than single ETTs, there is always a higher risk of airway edema and laryngeal injury and/or post-extubation stridor. Mass effects by tumors on the airway can have particular relevance in the choice and conduct of the anesthetic induction and maintenance techniques, as well as in lung isolation.
Positioning: Patients are placed in lateral decubitus position which enables full access to the operative hemithorax, and the possibility to perform multiple incisions for thoracoscopic access, as well as posterolateral, or a lateral thoracotomy, or any of their variations if needed or planned. This position also allows a standard or thoracoscopically-assisted pneumonectomy. A bean bag is used to achieve the patient’s optimal position and the kidney rest of the table should be at the level of the lower ribs. Flexing of the table allows widening of the intercostal spaces. An axillary roll should be placed to prevent axillary artery or brachial plexus compression. Special attention should be devoted to protect the pressure points in particular at the level of the elbows on the ulnar nerve. Most of these patients are at high-risk for peripheral nerve injury. The head and neck must have a neutral position with the body to avoid cervical spine and brachial plexus injuries. The lower leg should be flexed and the upper leg should be extended with adequate support from pillows in between them. The upper extremities can be either partially extended or flexed 90° depending on team’s preference and equipment. Proper precautions must be taken to avoid soft tissue or nerve injuries at pressure points such as eyes, ears, nose, nipples, deltoid muscle, genitals, iliac crest, ulnar, common peroneal, radial and sciatic nerves. Otherwise, if there is significant anterior mediastinal compromise by the mass, a median sternotomy on supine position is required.

c. Monitored Anesthesia Care

In general is not applicable for most pulmonary resections or for pneumonectomies.

6. What is the author's preferred method of anesthesia technique and why?

The anesthetic technique of choice includes the preoperative insertion of a thoracic epidural catheter for perioperative analgesia (if it offers proper benefit / risk balance to the patient) followed by general endotracheal anesthesia. The thoracic epidural analgesia should be implemented whenever possible given the discussed benefits. It also facilitates early extubation by providing dense analgesia with minimal decrease in respiratory drive and level of consciousness.

– Monitoring: Besides the use of required standard monitors per ASA guidelines, invasive monitoring should include continuous intra-arterial blood pressure due to the expected hemodynamic changes, and the need for perioperative arterial blood gas measurements. In general, most cases of wedge / nodulectomy and segmentectomy do not require central venous access and / or pulmonary artery catheter placement. For more extensive pulmonary resections central venous access should be considered on an individual basis. In the particular case of pneumonectomies, the insertion of a central venous catheter allows infusion of vasoactive medications, resuscitation with drugs and intravenous fluids, and measurement of central venous pressure which can provide a guide for judicious intravascular fluid management. In most instances, insertion of a pulmonary artery catheter (PAC) is not done due to the unreliable measurement of pulmonary artery (PA) pressures caused by several factors including; lateral position, the use of single lung ventilation, open thoracic cavity, and clamping of the contralateral PA. If PAC monitoring is necessary, care should be taken to pull back the catheter to the pulmonic valve before clamping and ligation of the PA to avoid entrapment. There is also the potential for causing disruption of the PA staple line when refloating the catheter. The use of transesophageal echocardiography (TEE) provides a more reliable and safer alternative to PAC in this circumstances. TEE is a also a more sensitive monitor of myocardial ischemia.

– Anesthetic technique: We prefer to avoid preoperative sedatives whenever possible in patients with lung disease due to their increased baseline CO₂ retention, and limited respiratory reserve. We also prefer to avoid benzodiazepines in particular, because they cause a significant impairment in the ventilatory response to hypercarbia and hypoxemia, even in patients without lung disease. Other issues include the increased incidence of postoperative delirium and cognitive dysfunction in the elderly population. Moreover, residual sedative effects can delay emergence at the end of the procedure. It is also important to limit the use of opioids and their total dosage for induction and/or early stages of the surgery only, given the risk of postoperative respiratory depression. Opioids should ideally be limited to epidural administration where their systemic absorption and side effects are decreased. In any case, avoid the use of any epidural opioids less than one hour before the end of surgery.

The choice of induction agent should take into consideration the possibility of bronchospasm and/or histamine release, and the profile effects of the particular agent in relationship with the patient’s physiology. Tailor the choice and use of neuromuscular blocking agents to obtain the minimal amount of respiratory dysfunction at the end of the procedure. The use of epidural analgesia limits the need for high degree of neuromuscular blockade. Remember that patients with lung disease are very sensitive to minimal decreases in muscular function. Otherwise, all anticholinesterase agents used to reverse neuromuscular blockers can increase airway resistance, and cause bronchospasm.

The need for prompt extubation makes necessary the use of short-acting inhalational and/or intravenous anesthetic agents. There is no proven advantage for the use of intravenous versus inhalational anesthetics for maintenance of anesthesia, when either one are combined with thoracic epidural analgesia. Nonetheless, we prefer to use continuous infusion of propofol with or without remifentanil as maintenance technique, because inhalational agents are eliminated more slowly in direct proportion to the impairment of gas exchange of the patient. Inhalational agents also inhibit hypoxic pulmonary vasoconstriction (HPV), impairing gas exchange during single lung ventilation. Minimal residual doses of inhalational agents as low as 0.1 MAC can depress the ventilatory response to hypoxemia by as much as 50%. The use of remifentanil has the advantage of blunting the hemodynamic responses during key portions of the procedure, and its elimination is reliable and independent of liver and renal function.

The short-acting inhalational agents are useful because of their potent bronchodilating properties and blunting of airway reflexes. Their use is more justified in patients with lesser degrees of respiratory dysfunction, and/or gas exchange impairment.

– Lung isolation techniques: A collapsed and still operative lung is an essential requirement for most pulmonary resections. It is particularly important for successful thoracoscopic / VATS techniques and for pneumectomy. At the same time, oxygenation and ventilation have to be adequate with single lung ventilation. Lung isolation can be achieved by intubation with DLTs or by using bronchial blockers. DLTs allow rapid lung collapse and ventilation with the possibility of suctioning or applying CPAP to the operative lung, and uninterrupted lung isolation at the time of bronchial surgical clamping. In contrast, bronchial blockers do not allow to suction the operative lung, and have to be withdrawn before bronchial clamping to avoid being trapped in the suture line. With the use of bronchial blockers, there can be contamination of the non-operative lung with secretions, and ventilation must be stopped after bronchial blocker withdrawal prior to bronchial clamping to avoid operative lung reinflation. The first alternative for right-sided pulmonary resections and right pneumonectomies is left DLT placement. Bronchial blockers, particularly right-sided ones may be dislodged during surgical manipulation. Right-sided DLTs are effectively used for left-sided pulmonary resections and left pneumonectomy, but placement and maintenance is more technically challenging given the short right upper lobe origin. A bronchial blocker passed via the tracheal lumen may be used to seal a poorly fitting right-sided DLT. The use of left-sided DLTs for left pneumonectomy is acceptable, but it has the caveat that the tube must be pulled back to allow bronchial clamping, and there is risk of disrupting the bronchial staple line if the tube is unintentionally moved into the bronchial stump. Finally, bronchial blockers have the advantage of being more easily positioned than DLTs in patients with difficult airway anatomy.

What prophylactic antibiotics should be administered? – As per SCIP guidelines, beta-lactam antibiotics are the prophylaxis of choice. The first choice in non-allergic patients are intravenous cefazolin 1 g. or cefuroxime 1.5 g., no more than 1 hour before surgical incision. In patients with allergy to beta-lactam antibiotics, vancomycin (20 mg/kg as single dose), or clindamycin are acceptable alternatives. Besides surgical site infections, postoperative pneumonia is a significant cause of postoperative morbi-mortality particularly after pneumonectomy (mortality > 20%). Recent evidence suggest, that although second-generation cephalosporins (cefuroxime) reduce surgical site infections and empyema, it does not have proven efficacy against pneumonia. The use of antibiotics against bronchial flora can significantly decrease the incidence of pneumonia, and postoperative mortality. This benefit has been shown with amoxicillin-clavulanate. Further studies are ongoing.

What do I need to know about the surgical technique to optimize my anesthetic care?

Types of pulmonary resections:

Nodulectomies, wedge resections or wedge / biopsies are the less extensive resections and many times are used for benign disease or for diagnostic purposes. These procedures do not require an “anatomical” resection of complete lung units. In some occasions when the lesions to resect are peripheral or pleural, lung collapse is not mandatory.

Segmentectomies and lobectomies are “anatomical” resections which require removal of full anatomical lung units to decrease the possibility of complications. These are more extensive procedures and require lung collapse / isolation. Most of the same considerations mentioned for pneumonectomies are applicable to lobectomies. Most likely, these resections are performed via thoracoscopy / VATS as first choice. VATS procedures require several limited incisions for insertion of the videoscope and two or three additional instruments.
Types of pneumonectomies:

Standard “open” pneumonectomy: Usually performed for resection of bulky and central carcinomas. It requires appropriate exposure usually via postero-lateral thoracotomy. This extensive procedure requires division of the latissimus dorsi, trapezius and serratus muscles. There is a significant degree of postoperative pain and functional impairment. The use of epidural analgesia and multimodal analgesia is highly desirable. The procedure can be performed also via modified or “muscle sparing approaches”. In this later instance, ideal positioning, flexion of the table and muscle relaxation are crucial to facilitate optimal surgical exposure through a limited incision. Muscle sparing approaches offer the advantage of improved early respiratory mechanics, and less pain. Later complications such as persistent incisional pain, reduced arm strength and frozen shoulder are less probable. The final surgical procedure to be performed depends always on intraoperative staging after bronchoscopy, mediastinoscopy and assessment of local-regional spread of the malignancy.

Sleeve pneumonectomy (or tracheal sleeve pneumonectomy): It is an extended resection for tumors compromising the lower trachea, carina, or the tracheobronchial angle, and the lung. It requires careful assessment of the feasibility of a tension-free anastomosis. It is more frequently performed for the right lung given the low incidence of proximal lesions on the left lung, and the technical difficulties due to the longer left main stem bronchus, and the presence of the aortic arch. The main issue is to provide adequate ventilation while sharing control of the airway with the surgical team during carinal resection. There are several options: to use a long single lumen ETT that can be advanced through the divided tracheal lumen into the unresected main bronchus, use of a DLT which is generally difficult to advance beyond the carina due to their size and rigidity. The most feasible option is to ventilate the distal airway using a sterile ETT attached to a breathing circuit over the sterile field. Intermittent high-frequency jet ventilation can also be used with this last method.

Minimally invasive pneumonectomy (VATS or thoracoscopically-assisted pneumonectomy): The indications, advantages and long-term benefits are still controversial. It usually is indicated for patients with centrally located lesions who are not candidates for sleeve pneumonectomy. The thoracoscopic approach provides additional visualization allowing decreased incisions size. Larger tumors (> 5 cm) and lesions with extensive mediastinal or chest wall invasion are not resected using this approach.

Extra-pleural pneumonectomy: It is the surgical procedure of choice for maximal cytoreduction as part of the multimodal treatment of malignant pleural mesothelioma (combined with postoperative radiation and chemotherapy). This procedure entails exposure and dissection of the parietal pleura from the chest wall, diaphragm, and mediastinum. Followed by en bloc resection of lung, pleura, pericardium and diaphragm while controlling the pulmonary vessels and bronchus. The last stage is reconstruction of the diaphragm and pericardium. This procedure is characterized by a more significant blood loss due to blunt dissection of the chest wall and an increased risk of major vascular injury. Therefore, it requires appropriate vascular access, availability of blood products, and fluid warming capabilities. The more extensive surgical manipulation also causes more pronounced hemodynamic changes, due to impaired venous return, compression of the heart and major vessels, and higher incidence of arrhythmias. The manipulation also causes more significant changes in the physiology of the non-operative lung (possible restriction and predisposition to atelectasis). Other important issues are probable disruption of left internal mammary artery coronary grafts whenever they are present during a left sided procedure, and ST-segment changes during the final washout phase of the surgery.
What can I do intraoperatively to assist the surgeon and optimize patient care? – After induction, single lumen ETT size 8.0 or larger is used to allow passage of the scope for the initial bronchoscopy if planned mostly for staging purposes only. The single lumen ETT is exchanged for a DLT. The use of 100% oxygen before lung isolation expedites the collapse of the operative lung after isolation. Management of hypertension significantly reduces blood loss and facilitates surgical exposure by decreasing surgical bleeding. This is probably more significant during more extensive resections. During extrapleural pneumonectomy, mild changes in blood pressure become significant by increasing surgical bleeding in extensively exposed areas with many bleeding blood vessels. Before chest closure, the bronchial stump is tested for air leaks with continuous positive airway pressure at 20-40 cmH₂O in coordination with the surgical team. At the end of the procedure, the DLT is exchanged for a single lumen ETT to perform a bronchoscopic evaluation of the stump and cleaning of the non-operative lung (if indicated usually for extensive pulmonary resection, especially pneumonectomy). A restrictive fluid management strategy (~ 20 mL/kg for the first 24 hours) should be used in order to decrease the possibility of post-lung resection or post-pneumonectomy pulmonary edema. Some have advocated the use of low FiO₂ during lung resection surgery, particularly in cancer patients after induction radio- and chemotherapy. The potential risk of pulmonary oxygen toxicity / acute lung injury should be balanced against the risk of intraoperative hypoxemia.

What are the most common intraoperative complications and how can they be avoided/treated? –

Cardiac complications – Hypotension is the most common intraoperative complication. The main cause of hypotension is decreased venous return due to surgical manipulation. Hypotension is exacerbated by hypovolemia and vasodilation. Other causes of hypotension are: air trapping (auto-PEEP), arrhythmias, tension pneumothorax, and right heart dysfunction or failure. In general, hypotension should improve after the specimen is removed and with decreased surgical manipulation. Hypotension must not be treated with high volume of intravascular fluids. Instead, use vasopressors and transfusion of blood products if necessary. Myocardial ischemia is difficult to detect due to altered positioning of the ECG leads in the lateral position. TEE may be useful for early diagnosis of myocardial ischemia. If there is suspicion for myocardial ischemia, improve balance of oxygen delivery / consumption. Significant ST-segment elevations are common during the washout with warm normal saline performed at the end of extrapleural pneumonectomies. These changes are most probably related to myocardial warming, and surface electrolytic changes; as such, they are usually transient and not related to myocardial ischemia. Intraoperative arrhythmias (usually SVT) are most commonly caused by mechanical irritation, and are more frequent during extrapleural pneumonectomy. Predisposing factors are in general mechanical irritation, in particular intrapericardial dissection, right pneumonectomy (more than left-sided), the extent of resection, and advanced age. It is advisable to attach transcutaneous defibrillator leads after induction in susceptible patients.
Pulmonary – Hypoxemia is most commonly caused by shunting of blood flow to the operative / non-ventilated lung. An important factor is the inhibition of hypoxic pulmonary vasoconstriction (HPV) caused by the multiple endogenous substances released during surgical manipulation. Other contributing factors are, significant pathology in the non-operative lung, supine position and restrictive physiology in the non-operative lung (which can be exacerbated by tumor weight and surgical compression). Hypoxemia during OLV is treated by 100% oxygen ventilation, while assuring an adequate DLT position and suctioning of secretions by bronchoscopy. Persistent hypoxemia require application of PEEP to the ventilated lung (to resolve atelectasis, and to improve alveolar recruitment), and application of continuous positive-airway pressure (CPAP) to the operative lung. Other measures include, intermittent reinflation / ventilation of the surgical lung, and reduction of blood flow through the surgical lung pulmonary artery.
Cardiac Herniation: This complication can occur upon returning to supine position only after pneumonectomy. The sudden shift of the heart into the empty thoracic cavity causes torsion of the great vessels and hemodynamic collapse. Chest compressions and pharmacologic maneuvers are ineffective. The treatment is immediate return to the preexisting lateral decubitus position. This complication is more common after right pneumonectomy. Less significant degrees of hemodynamic instability can occur due to partial herniation or mediastinal shift in either direction, causing decreased venous return. Careful management of the air/fluid in the empty thoracic cavity can be done by intermittent evacuation via the chest drain. Some institutions transduce intrathoracic pressure postoperatively to guide fluid drainage before appearance of symptoms. A portable chest-x-ray in the OR to assess for mediastinal shift can help to confirm the diagnosis, and to guide initial therapy. Excessive fluid accumulation in the operative hemithorax can also compromise respiratory mechanics and lung function in the contralateral side.
Postpulmonary resection / Postpneumonectomy pulmonary edema (acute lung injury): It is an uncommon complication after pulmonary resection surgery. It occurs more frequently after pneumonectomy. It occurs approximately in 2-4 % of pneumonectomy patients, but it has a mortality rate > 50%. The cause is not completely clear, but it is suggested that increased capillary permeability, endothelial shear stress, and ventilator-associated lung injury in the remaining lung parenchyma play a major role. Excessive volume resuscitation may contribute to its development. High intraoperative ventilatory pressure index (combined airway pressure and time) is also implicated. It is suggested to limit intravenous fluid administration to < 3 L of crystalloids in the first 24 hours. It is recommended to limit Vt to 5-6 mL/Kg, ideal body weight; and to limit peak inspiratory pressure to < 35 cm H2O, as well as plateau inspiratory pressure to < 25 cm H20 during OLV.

a. Neurologic:

Neurologic complications are specific to the patient baseline comorbidities. Atrial fibrillation increases the risk of perioperative stroke.

b. If the patient is intubated, are there any special criteria for extubation?

It is essential to have a completely awake patient with minimal pain, who is able to protect the airway. Careful attention should be paid to the possible presence of vocal cord paralysis given the life-threatening consequences of aspiration and pneumonia in patients with lung disease after pulmonary resection, particularly after pneumonectomy. Patients with any hoarseness and weak cough must have immediate laryngoscopic evaluation and treatment.

c. Postoperative management

What analgesic modalities can I implement? – The recommended technique is preoperative thoracic epidural catheter insertion and continuous infusion of a combination of diluted local anesthetic and an opioid. Bupivacaine 0.0625 – 0.125% plus hydromorphone minimizes motor blockade and opioid side effects. Bupivacaine offers long duration of action and minimal motor effect. Hydromorphone has lower systemic absorption and respiratory depression, with wider segmental spread than fentanyl, given its intermediate hydrophylicity. An initial fentanyl bolus can achieve rapid affect. After catheter placement and testing, lidocaine 1-2 % or bupivacaine 0.25% bolus of 2-5 mL can be used to elicit a dense segmental block before surgical incision. Otherwise, local anesthetic boluses 3-5 mL every hour can be used to optimize the analgesic level. A continuous infusion provides better hemodynamic stability than boluses. If thoracic epidural analgesia is contraindicated, other regional techniques can be used as part of a multimodal regimen that can minimize systemic opioids requirements. These include, thoracic paravertebral / extrapleural analgesia, lumbar intrathecal opioids, intercostal nerve blockade, interpleural local analgesia, intraoperative phrenic nerve blockade, and nerve blocks for shoulder pain. Pharmacologic adjuncts that can be used for acute postoperative pain in selected cases include NSAIDs, ketamine and some anticonvulsants.

What level bed acuity is appropriate? – Postoperative care setting should be selected on the basis of expected complications given age, presence of fibrotic lung disease, poor baseline lung function, and high cardiovascular risk assessment. As such, patients at high-risk due to extensive resection or the above mentioned factors should benefit from ICU elective admission. Selected postoperative pulmonary resection patients as well as pneumonectomy patients should go to an ICU with experience in the particular management of postoperative issues; given the high-risk surgical procedure, high incidence of postoperative complications, as well as the complexity and comorbidities of this patient population.

What are common postoperative complications, and ways to prevent and treat them?

Cardiac: Arrhythmias, particularly atrial fibrillation are the most common postoperative complication (~20-30 %). They are caused by mechanical surgical irritation, inflammatory changes, sympathetic stimulation, and atrial stretch after lung resection. Intraoperative occurrence does not predict postoperative continuation. Pharmacologic prophylaxis has not been proven effective. It is important to continue antiarrhythmic medications perioperatively. Arrhythmias should be treated early and aggressively, to decrease the risk of stroke and long-term hemodynamic consequences. The use of amiodarone should be avoided when possible in particular, with extensive lung resection or in patients with very poor lung function or in pneumonectomy patients when the risk of pulmonary toxicity is higher than the expected benefit. Pericardial tamponade occurs most commonly between postoperative days 2 to 4, as consequence of retained pericardial effusion, inflammatory epicarditis, or a constrictive pericardial patch (last two during extra-pleural pneumonectomy). Tamponade physiology should be diagnosed promptly with TEE whenever suggested by any signs of hypoperfusion. Management usually requires surgical exploration. Myocardial ischemia and infarction are less common, but can be confused with pericarditis.
Pulmonary: Includes respiratory failure and prolonged intubation, aspiration, and ALI/ARDS. In many cases, vocal cord paralysis is a determining factor and should be immediately diagnosed and treated in susceptible patients, such as those with extensive aorto-pulmonary and subclavian dissections. Frequent bronchoscopy and vigorous diuresis are key for preventing complications.
DVT / PE: DVT and PE are common, and both have high and separate risks of mortality. Higher pack-years of smoking is associated with greater risk. Prevention requires preoperative screening with duplex studies in selected patients, and combination of mechanical and pharmacologic prophylaxis (the later for at least a month after surgery). All patients should have postoperative duplex on day 7 (when occurrence peaks). Patients with poor preoperative pulmonary function have lower survival.
Infectious: Empyema is the most common infectious complication, and should be treated with broad spectrum antibiotics, and surgical drainage / lavage.
Other: AKI / renal failure is related to ARDS and multisystem organ dysfunction. It has a high mortality rate. Technical complications include postoperative bleeding, chylothorax, bronchopleural fistula, and diaphragmatic hernia (after extra-pleural pneumonectomy). These complications usually require surgical management.

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