Anesthesiology

Craniofacial reconstruction

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What the Anesthesiologist Should Know before the Operative Procedure

Craniofacial reconstruction is defined as surgery to reconstruct any part of the craniofacial skeleton but generally refers to repair of craniosynostosis, midface hypoplasia, or micrognathia. The repair for craniosynostosis can be open or endoscopic. Open craniosynostosis repair (cranial vault reconstruction which can be a frontal orbital advancement, posterior vault reconstruction, or total cranial vault reconstruction) is accomplished by removing the calvarium in separate pieces and reshaping the pieces to reshape and enlarge the cranial vault. Midface repair (Lefort 3 advancement) involves advancing the midface and can be performed as a single step or with distraction osteogenesis. Monoblock advancement combines a frontal orbital advancement with a midface advancement. This can also be performed as an open procedure or with distraction. Likewise, micrognathia can also be repaired with distraction osteogenesis.

The critical issues for pediatric patients presenting for craniofacial reconstruction include young age (often <1 year old), bleeding involving half to one blood volume, venous air emboli, and increased intracranial pressure. Syndromic patients may have obstructive sleep apnea and may also be difficult to ventilate and intubate.

1. What is the urgency of the surgery?

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

Typically craniofacial reconstruction is not emergent or urgent. However, if craniosynostosis is not diagnosed early on in infancy, a child may suffer from long standing chronic increased intracranial pressure that can rarely but acutely escalate. In this clinical setting, the patient may present with headaches and acute visual loss. These patients need to undergo an emergency cranial vault reconstruction.

Emergent: In addition to the issues outlined for elective surgery, patients presenting for emergent cranial vault reconstruction all have an acute elevation in intracranial pressure. These patients are at risk for aspiration and increased bleeding. They are also older (>1 year old).

Urgent: The issues are the same as the emergent scenario.

Elective: The critical issues for pediatric patients presenting for elective craniofacial reconstruction include young age (often <1 year old), bleeding involving half to one blood volume, venous air emboli, and increased intracranial pressure. Syndromic patients may have obstructive sleep apnea and may also be difficult to ventilate and intubate.

2. Preoperative evaluation

  1. Presence of a syndrome that is associated with craniosynostosis, midface hypoplasia or micrognathia (Apert, Pfeiffer, Crouzon, Seathre-Chotzen, Carpenter, Pierre-Robin). Some syndromes may present with a difficult airway (see below).

  2. Increased intracranial pressure in patients with craniosynostosis. Patients should be seen by ophthalmology

  3. The presence of a syndrome like Apert, Pfeiffer or the presence of a heart murmur is an indication to evaluate for congenital heart disease.

  4. Obstructive sleep apnea may be present in patients with midface hypoplasia or micrognathia.

  5. Preoperative hematology evaluation should include hematocrit, platelets, PT, PTT, and closing time. Some patients may be placed on synthetic erythropoietin (epogen) preoperatively. Epogen dosing is 600 units/kg per week for 4 to 6 weeks prior to surgery. Pediatric patients should receive iron therapy while on epogen.

Delaying surgery may be indicated if the patient presents with an upper respiratory tract infection with fever, purulent drainage, change in behavior, or abnormal lung sounds, consideration should be given to postponing the surgery for 2 to 6 weeks.

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

There are six syndromes associated with craniosynostosis and midface hypoplasia and one sequence commonly associated with micrognathia. The most four most common are discussed below.

Apert syndrome

Craniosynostosis (coronal), midface hypoplasia, choanal atresia, proptosis, congenital cardiac disease in 10% of Apert patients, syndactyly, developmental delay, may have increased intracranial pressure, may have fused cervical vertebrae.

  1. Perioperative evaluation: May require preoperative ECHO, preoperative HCT, PTT, PTT, PLT, closing time.

  2. Perioperative risk reduction strategies: May be difficult to mask ventilate and/or intubate. Airway obstruction may occur intraoperatively or postoperative. May have significant blood loss. An arterial catheter and possibly central venous catheter will be required. Transfusion of half to one blood volume is common during craniosynostosis repair, midface advancement, or monoblock advancement. Vascular access and arterial catheter placement may be difficult with syndactyly. Proptosis may increase risk for corneal abrasion or globe pressure.

Pfeiffer syndrome

Craniosynostosis (coronal or sagittal), midface hypoplasia, proptosis, OSA, congenital cardiac disease uncommon, broad fat thumbs and great toes, and developmental delay may occur and may have increased intracranial pressure. Cervical fusion is less common.

  1. Perioperative evaluation: May require preoperative ECHO, preoperative HCT, PTT, PTT, PLT, closing time.

  2. Perioperative risk reduction strategies: May be difficult to mask ventilate. Generally not difficult to intubate. Airway obstruction may occur intraoperatively or postoperatively. May have significant blood loss. An arterial catheter and possibly central venous catheter will be required. Transfusion of 1/2 to 1 blood volume is common during craniosynostosis repair, midface advancement, or monoblock advancement. Proptosis may increase risk for corneal abrasion or globe pressure.

Crouzon syndrome

Craniosynostosis (coronal or lambdoid), beaked nose, midface hypoplasia, proptosis, OSA, and may have increased intracranial pressure. Occasional mild developmental delay. No hand anomalies.

  1. Perioperative evaluation: Preoperative HCT, PTT, PTT, PLT, closing time.

  2. Perioperative risk reduction strategies: May be difficult to mask ventilate. Generally not difficult to intubate. Airway obstruction may occur intraoperatively or postoperatively. May have significant blood loss. An arterial catheter and possibly central venous catheter will be required. Transfusion of 1/2 to 1 blood volume is common during craniosynostosis repair, midface advancement, or monoblock advancement. Proptosis may increase risk for corneal abrasion or globe pressure.

Pierre-Robin sequence

Small mandible (micrognathia), glossoptosis (posteriorly displaced tongue), airway obstruction. Majority of patients have a cleft palate.

  1. Perioperative evaluation: Preoperative HCT, PTT, PTT, PLT, closing time.

  2. Perioperative risk reduction strategies: May be difficult to mask ventilate and intubate. Airway obstruction may occur intraoperatively or postoperatively. Intubation may require intubating through an LMA, or using a fiberoptic scope, or glide scope. May require a tracheostomy.

b. Cardiovascular system:

Baseline coronary artery disease or cardiac dysfunction – goals of management

Patients should be evaluated for the presence of a heart murmur. If patients have congenital heart disease with intra-atrial or intraventricular communication, they may be at risk for paradoxical air emboli during cranial vault reconstructions which could result in a neurologic injury. Patients with heart murmurs should be evaluated with echocardiography.

c. Pulmonary:

  1. Midface hypoplasia and/or micrognathia may make mask ventilation and intubation difficult.

  2. Obstructive sleep apnea may increase opioid sensitivity in pediatric patients.

d. Renal-GI:

N/A

e. Neurologic:

Patients with craniosynostosis may have elevated intracranial pressure. Usually this is chronic but rarely may be acute.

Acute issues: Acutely elevated intracranial pressure requires a rapid sequence intubation. Patients may also have more blood loss.

Chronic disease: Chronically elevated intracranial pressure does not typically increase the risk of aspiration. However, patients may have more bleeding during the surgical procedure and may have a significant decrease in blood pressure once the calvarium is removed. This may require pressors to stabilize the blood pressure.

f. Endocrine:

N/A

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

N/A

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

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

N/A

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

N/A

j. How to modify care for patients with known allergies

N/A

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

N/A

l. Does the patient have any antibiotic allergies - Common antibiotic allergies and alternative antibiotics

N/A

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

Malignant hyperthermia (MH)

Documented: Avoid all trigger agents such as succinylcholine and inhalational agents. Follow a proposed general anesthetic plan: total intravenous anesthesia with propofol ± opioid infusion ± nitrous oxide. Ensure that an MH cart is available [MH protocol].

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

Typical preoperative laboratory tests for cranial vault reconstruction, midface advancements, or monoblock advancements include preoperative CBC (HCT, PLT), PT, PTT, closing time. Patients receiving epogen preoperatively will have HCT's checked during epogen administration (several times over 6 weeks).

  1. Hemoglobin levels: Preoperative HCT

  2. Electrolytes: Preoperative sodium may be indicated

  3. Coagulation panel: Preoperative PT, PTT, PLT, closing time

  4. Imaging: Preoperative head and face CT scan

  5. Other tests: Patients with OSA may have polysomnography

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

Patients presenting for cranial vault reconstruction (open or endoscopic), midface advancement, or mandibular distraction will all require general anesthesia. Patients with syndromes presenting for any of the above surgeries or patients having mandibular distraction may be difficult to intubate and ventilate and may require alternative techniques for ventilation and /or intubation.

Cranial vault reconstruction, midface advancements, and monoblock advancements cause significant bleeding. There is increasing evidence that antifibrinolytic agents, specifically tranexamic acid (10-100 mg/kg IV loading dose, followed by 10 mg/kg/hr), reduce blood loss and exposure to allogeneic blood.

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

What prophylactic antibiotics should be administered?

Prophylactic antibiotics are recommended for all cranial facial reconstructions. Cefazolin 25 mg/kg is a standard antibiotic administered within one hour of skin incision. This can be repeated every six hours during the reconstruction. Patients with cephalosporin allergies can be administered clindamycin 10 mg/kg.

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

Craniosynostosis repair is performed endoscopically or open. Endoscopic repair may involve less intraoperative bleeding and shorter hospital stays. The open approach will involve more bleeding and hospital stays of 4-5 days. Patients having cranial vault reconstruction, or monoblock advancement have an oral endotracheal tube placed. Patients having mandibular distractors placed may need to be nasally intubated.

What can I do intraoperatively to assist the surgeon and optimize patient care?

1. Blood salvage is optimized with the use of preoperative epogen and cell saver. Cell saver systems with a smaller collection reservoir (25-50 mL) are optimal for pediatric cell salvage. Other measures to minimize blood loss include using antifibrinolytics like tranexamic acid and maintaining the mean arterial blood pressure between 50 to 60 mmHg.

2. Prior to opening the calvarium, the patient should be optimized for the neurosurgeon with brain relaxation. This is especially true for patients with acutely or chronically elevated ICP. Reducing brain volume with mannitol (0.25-0.75 mg/kg) may be beneficial.

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

1. Venous air embolism is a very common event during cranial vault reconstruction. Preventing air entry is best achieved by maintaining the head level with the heart, maintaining euvolemia, and early detection with a precordial Doppler.

2. Hemorrhage from skin, bone and dura is constant throughout cranial vault reconstructions. Occasionally acute hemorrhage can occur from large bridging veins. Adequate intravenous access (two or more large bore intravenous catheters [20-18 gauge]), cell salvage, and immediate access to blood are essential in the resuscitation of these patients.

Cardiac complications: Venous air emboli can result in cardiac arrest. Resuscitation with chest compressions and epinephrine may be required.

Pulmonary: Rarely patients have developed pulmonary complications (TRALI) from intraoperative blood tranfusions.

a. Neurologic:

N/A

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

Patients can usually be extubated at the end of cranial vault reconstruction surgery. The decision to extubate will depend on the presence of a difficult airway, and intraoperative complications from bleeding or air emboli. Patients having mandibular distractors placed are not extubated at the termination of surgery. They are transported to an intensive care unit and remain intubated for several days. They are transported back to the operating room for extubation in the presence of the anesthesiologist, plastic surgeon, and ENT.

c. Postoperative management

What analgesic modalities can I implement?

Tylenol 10 to 15 mg/kg PO every 4 to 6 hours scheduled for 48 to 72 hours. Morphine 0.05 to 0.1 mg/kg every 2 to 4 hours PRN. May need to reduce the morphine dose if there is moderate or severe OSA. No NSAIDs.

What level bed acuity is appropriate?

Patients require intensive care for 1 to 2 days for cranial vault or monoblock reconstructions. Patients having mandibular distractors placed require up to one week of critical care for intubation and respiratory care.

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

Hyponatremia is common following open cranial vault reconstructions (30%). Intraoperative and postoperative intravenous fluids should be near iso-osmotic (lactated ringers, normal saline, or plasmalyte) and serum sodiums should be evaluated daily for 48 hours. Hypo-osmotic fluid (half normal saline) increases the risk of hyponatremia.

What's the Evidence?

Bannink, N, Joosten, K, van Veelen, M. "Papilledema in patients With Apert, Crouzon, and Pfeiffer syndrome: prevalence, efficacy of treatment, and risk factors". J Craniofacial Surg. vol. 19. 2008. pp. 121-7.

(This paper demonstrates the incidence and importance of increased in ICP in craniosynostosis, especially in the syndromic patients.)

Cladis, FP, Bykowski, M, Schmitt, E. "Postoperative hyponatremia following calvarial vault remodeling in craniosynostosis". Paediatr Anaesth. 2011.

(Hyponatremia after calvarial vault remodeling is common (30%) but not often not clinically significant.)

Mixter, RC, David, DJ, Perloff, WH. "Obstructive sleep apnea in Apert’s and Pfeiffer’s syndrome: more than a craniofacial abnormality". Plast Reconstr Surg. vol. 86. 1990. pp. 457-63.

(OSA is a significant concern in patients with midface hypoplasia. It can affect intraoperative and postoperative management.)

Sirotnak, J, Brodsky, L, Pizzuto, M. "Airway obstruction in the Crouzon syndrome: case report and review of the literature". Int J Pediatr Otolaryng. vol. 31. 1995. pp. 235-46.

(Postoperative airway obstruction in patients with Crouzon (and possibly any patient with midface hypoplasia) is common and can be clinically significant.)

Brown, KA, Laferriere, A, Moss, IR. "Recurrent hypoxemia in young children with obstructive sleep apnea is associated with reduced opioid requirements for analgesia". Anesthesiology. vol. 100. 2004. pp. 806.

(OSA and recurrent hypoxia increases opioid sensitivity in pediatric patients. Reduction in postoperative opioid dosing in these patients is advised.)

Jimenez, DF, Barone, CM, Cartwright, CC. "Early management of craniosynostosis using endoscopic-assisted strip craniectomies and cranial orthotic molding therapy". Pediatrics. vol. 110. 2002. pp. 97-104.

(The endoscopic approach for synostosis repair is an option for single suture craniosynostosis and it may reduce blood loss and hospital stay.)

Krajewski, K, Ashley, RK, Pung, N. "Successful blood conservation during craniosynostotic correction with dual therapy using Procrit and Cell Saver". J Craniofac Surg. vol. 9. 2008. pp. 101-5.

(This paper suggests that the two most effective strategies to maximize blood conservation during craniosynostosis repair is preoperative Epogen and cell salvage with a pediatric collection reservoir.)

Goobie, SM, Meier, PM, Pereira, LM. "Efficacy of tranexamic acid in pediatric craniosynostosis surgery: A double blind placebo controlled study". Anesthesiology. vol. 114. 2011. pp. 862-71.

(Tranexamic acid reduces allogeneic blood requirements in infants having craniosynostosis surgery.)

Faberowski, LW, Black, S, Mickle, JP. "Incidence of venous air embolism during craniectomy for craniosynostosis repair". Anesthesiology. vol. 92. 2000. pp. 20-3.

(Venous air embolism during calvarial vault reconstruction surgery is common but often not clinically significant.)

Stricker, P, Shaw, T, Desouza, DG. "Blood loss, replacement, and associated morbidity in infants and children undergoing craniofacial surgery". Pediatr Anesth. vol. 20. 2010. pp. 150-9.

(Blood loss during craniofacial reconstruction remains a significant clinical issue and a significant cause of morbidity.)
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