Anesthesia for plastic surgery

Apert.

Apert syndrome, also referred to as acrocephalosyndactyly, is an example of syndromic craniosynostosis and occurs at a frequency of 1 in 65,000 to 88,000 live births ( http://ghr.nlm.nih.gov/condition/apert-syndrome ; ). Acrocephalosyndactyly, a defect involving the cranium and the extremities, includes Apert, Pfeiffer, Carpenter, and Saethre-Chotzen syndromes. The characteristic features of Apert syndrome include turribrachycephaly (high, steep, flat forehead and occiput), midface hypoplasia, and orbital hypertelorism ( Fig. 35.2 ). Cleft palate occurs in approximately 30%. Choanal atresia and occasionally tracheal stenosis have been reported and can cause airway obstruction. Hydrocephalus and Chiari malformation type 1 are common and may require surgical interventions in 24% and 80%, respectively ( ). Cervical spine abnormalities are common in Apert syndrome and include fusion of the posterior elements of C5–C6 in 50%, C3–C4 in 27%, and multilevel fusion in 20% of patients ( ; ). Some authors have recommended cervical spine films prior to anesthesia because this may help predict difficult intubation ( ).

Congenital cardiac disease and genitourinary anomalies (hydronephrosis, cryptorchidism) occur in approximately 10% with Apert syndrome ( ). Severe synostosis can result in increased ICP and, if uncorrected, developmental delay. Evidence suggests that children with syndromic synostosis, like Apert syndrome, have an increased risk for intellectual disability and behavioral problems ( ). Syndactyly of the hands and feet with the fusion of digits 2 to 4 can make intravenous (IV) access difficult.

Infants and children with Apert syndrome may be difficult to intubate and may require videolaryngoscopy and/or flexible fiberoptic intubation. The laryngeal mask airway (LMA) may be a reasonable adjunct in those patients that are difficult to ventilate or intubate. However, to date there is only one case report ( ) of their use in infants and children with Apert syndrome. The clinical features and the anesthetic implications of Apert syndrome and the other acrocephalosyndactylies are outlined in Table 35.1 . Unlike Apert syndrome, the other acrocephalosyndactylies are not typically associated with difficult airways. However, midface hypoplasia is a component of this syndrome, and these infants may have significant upper airway obstruction preoperatively, intraoperatively, and postoperatively ( ). In a series of 509 anesthetics in infants and children with Apert syndrome, airway obstruction was the most common complication. The obstruction occurred during induction and emergence and was typically resolved with continuous positive airway pressure (CPAP), jaw thrust, or an oropharyngeal airway ( ). Obstructive sleep apnea (OSA) is common in syndromic synostosis (40% to 85%). This obstruction may be more related to midface hypoplasia and nasal airway anomalies than to adenotonsillar hypertrophy. Removing the adenoids and tonsils in this population does not seem to relieve the obstruction as well as in nonsyndromic children ( ).

Pfeiffer.

Pfeiffer syndrome is another example of an acrocephalosyndactyly. The incidence of Pfeiffer syndrome is approximately 1 in 100,000 live births ( http://ghr.nlm.nih.gov/condition/pfeiffer-syndrome ). This syndrome is characterized by bicoronal synostosis, proptosis, midface hypoplasia, and broad thumbs and great toes ( ). Patients with Pfeiffer syndrome can also present with multiple neurologic abnormalities, including increased ICP, hydrocephalus, Chiari malformation type I, seizures, and cognitive delay ( ). There are three types of Pfeiffer syndrome. Type 1 is mild and presents with craniosynostosis, midface hypoplasia, and normal intelligence. Type 2 is more severe and includes multisuture synostosis (lambdoid, coronal, and sagittal) that results in a clover-leaf skull deformity. These patients are more likely to have ankylosis of the elbows, hydrocephalus, and developmental delay. Type 3 is similar to type 2 but without the clover-leaf deformity of the skull and elbow ankylosis. Typically, the neurologic abnormalities, degree of airway obstruction, and mortality increase with types 2 and 3 ( ; ).

Saethre-chotzen and carpenter syndrome.

The clinical features of Saethre-Chotzen syndrome include brachycephaly, facial asymmetry, low hairline, proptosis, beaked nose, large halluces (great toes), and pectus excavatum. Some may have renal anomalies, cryptorchism, developmental delay, and epilepsy. It can be difficult to differentiate it from the other acrocephalosyndactylies because there can be significant clinical variability ( ). Carpenter syndrome is the rarest of the syndromic craniosynostosis. The incidence is approximately 1 in 1 million, and there have only been about 100 reported cases since the mid-1990s ( http://ghr.nlm.nih.gov/condition/carpenter-syndrome ; ). As with all of the syndromic craniosynostoses, patients with Carpenter syndrome have synostosis, midface hypoplasia, and musculoskeletal deformities. Infants with Carpenter syndrome have several associated anomalies. As many as 70% will have some central nervous system abnormality, including cerebellar hypoplasia, developmental delay, lateral ventriculomegaly, Sylvian aqueduct dilation, pseudopapilledema, corpus callosum agenesis, and lumbar myelomeningoceles. Eighteen to fifty percent may present with congenital cardiac anomalies, including atrial septal defect (ASD), ventricular septal defect (VSD), pulmonic stenosis, and tetralogy of Fallot ( ). They may also have undescended testes, hypogonadism, and obesity ( ).

Crouzon.

Crouzon syndrome, also known as craniofacial dysostosis, is part of the syndromic craniosynostoses. It is the most common craniosynostosis syndrome and has an incidence of about 1 in 60,000 ( http://ghr.nlm.nih.gov/condition/crouzon-syndrome ). These infants present with craniosynostosis (typically coronal and sagittal), proptosis, and midface hypoplasia but without visceral or extremity involvement ( Fig. 35.3 ; also see Fig. 35.e1 ). As with the other patients with midface hypoplasia, significant airway obstruction can occur and rarely may require early tracheostomy ( ). Table 35.1 outlines the main clinical features and anesthetic issues as they relate to patients with Crouzon syndrome. During infancy, patients with Crouzon syndrome present to the operating room for cranial vault remodeling.

Open cranial vault.

The calvarial vault reconstruction is typically a combined procedure involving both plastic surgery (craniofacial surgeons) and neurosurgery. The surgical approach for an open cranial vault reconstruction depends on which part of the skull is being operated on. The initial skin incision for all of the open procedures is through a bicoronal incision ( Fig. 35.4 A). A blocking stitch or scalp clips may be applied to the skin flaps to minimize blood loss. The clips may be more effective in preventing bleeding, but some surgeons have expressed concern regarding their use because of the risk of ischemia of the underlying hair follicles (personal communication, Ray Harschberger 2009). For the fronto-orbital advancement, the scalp flap is dissected off of the forehead and mobilized down to expose the superior orbital rim (see Fig. 35.4 B). The calvarium is typically removed by the neurosurgeons in one or several pieces. A “bandeau” osteotomy is then performed along the lateral temporal bones and the nasion to mobilize the superior orbital rim (see Fig. 35.4 C). Once the osteotomies are complete, the surgical field is protected with moist gauze. The calvarium and the orbital bandeau are sectioned, and the pieces are reshaped and replaced in a manner that replicates a more normal head shape. The bone is secured with a craniofacial plating system, the scalp flaps are replaced, and the coronal incision is closed.

Strip craniectomy with helmet.

The endoscopic approach is less invasive and has been reported to result in less blood loss and shorter lengths of stay ( ; ). This procedure is more commonly used for sagittal synostosis, although it has been described for the repair of other single-suture, syndromic synostosis and even multisutural synostosis. The patients are typically younger (2 to 3 months), and they require postoperative helmet therapy for up to 6 months for the development of a normal head shape. The surgical approach is through smaller incisions than with the open vault. As with open approaches, significant blood loss can occur if the sagittal sinus is entered, but this is rare. Jimenez and colleagues reported a small percentage of patients that required transfusions, and most were discharged on the first postoperative day. Unlike an open calvarial reconstruction, the patients do require helmet therapy after this repair. In 2011 Meier and colleagues reported less blood loss and shorter lengths of stay with this approach. In this study, 8% still required a blood transfusion and 8% were admitted to the intensive care unit (ICU) overnight. Over 80% of these patients were discharged on postoperative day 1 ( ). Multivariate analysis suggests that infants with lower weight and syndromic synostosis were at higher risk of requiring a blood transfusion. Propensity-matched data from the Pediatric Craniofacial Database demonstrated a significant reduction in ICU days and shorter lengths of stay with endoscopic repair ( ). In addition, there is a reduction in transfusion requirements. Although complications like hypotension, venous air embolism (VAE), and hypothermia were similar between endoscopic and open repair, postoperative intubation was significantly less for those patients having an endoscopic repair.

Spring-mediated cranioplasty.

Craniofacial surgery has evolved from strip craniectomies to open cranial vaults and now back to less invasive maneuvers. The spring-mediated cranioplasty appears to be as effective while causing significantly less morbidity. The approach involves surgically removing the synostotic suture and placing a spring between the two bone edges. Over time (weeks) the force exerted on the two bone edges corrects the defect. A second operation is required to remove the spring. Early and later follow-up data suggest there is significantly less blood loss and shorter lengths of stay with this procedure. In 100 consecutive patients undergoing the spring-mediated cranioplasty, noted that none of the patients required a blood transfusion or an ICU admission ( ). A limitation of this procedure is that it is typically used for isolated sagittal synostosis.

Midface advancement.

Midface advancements are performed to correct midface hypoplasia. The different types of advancements include the Le Fort I maxillary advancement; the Le Fort III maxillary and upper face advancement ( Fig. 35.5 ); and the monoblock advancement, which includes the maxilla, upper face, orbits, and forehead. The monoblock is a combination of a Le Fort III with a fronto-orbital advancement. The Le Fort I osteotomy is typically performed for patients with maxillary hypoplasia secondary to cleft lips and palates. The Le Fort III and monoblock osteotomies are typically performed for patients with midface hypoplasia secondary to syndromic craniosynostosis (Apert, Pfeiffer, Crouzon). The surgical approach for the Le Fort III and monoblock osteotomies are through bicoronal, intraoral, and often eyelid incisions. Significant blood loss can occur during the Le Fort III surgical dissection and osteotomies. Once the midface is mobilized, the advancement can be immediately performed with rigid fixation or gradually with internal or external distraction osteogenesis. Distraction osteogenesis became more common in craniofacial surgery in 1997, and the advantages include less morbidity (less blood loss), more long-term stability, and improved aesthetic outcome ( ; ). The external distraction device has a frame that is anchored to the skull, with a distraction bar positioned perpendicular to the face. The distraction bar is anchored to the newly mobilized midface with wires ( Fig. 35.6 ). Once in place, the midface may be distracted at a rate of 1 to 2 mm a day.

Airway.

Airway management in these patients may be very challenging. The difficulty may present during attempts at ventilation, intubation, or both. Fortunately, difficult airways are not common. However, the incidence may be higher in those patients with syndromes and in those patients who have had previous reconstruction. In a case series of 61 infants and children with Apert syndrome undergoing over 600 general anesthetics over a 14-year period, only 3 patients (1.5%) were described as a Cormack and Lehane grade 3. None were grade 4 ( ). Many techniques have been successfully described in infants and children, and these include using the Bullard laryngoscope, LMA, flexible fiberoptic scope, and video laryngoscopes ( ; ; ; ). (See Chapter 17 : Equipment and Chapter 19 : Airway Management.) A combination of techniques may be required to secure the airway. For example, the LMA has been used to facilitate the passage of the fiberoptic scope and endotracheal tube (ETT) ( ; ) ( Fig. 35.7 A to D). Although the authors report this technique in patients with Treacher Collins and Apert syndromes, it could be employed with any craniofacial patient with a difficult airway. An ETT/LMA size chart is available to help choose the appropriate equipment in Chapter 17 ( Table 17.3 ). Cuffed ETTs may be more challenging to use because the cuff on the ETT may not fit through the smaller LMAs. However, the AirQ, with its short stalk and detachable adapter, makes it easy to pass a normally sized cuffed ETT with the pilot balloon. An uncuffed ETT or a commercial-grade “pusher” can be used to remove the LMA by telescoping through the top of the ETT (see Fig. 35.7 A to D).

The airway for patients having craniosynostosis surgery can be secured with a standard oral ETT. A nasal intubation may be easier to perform when using the flexible fiberoptic scope, and this route can be used for patients having craniosynostosis surgery. A standard ETT is preferred to a nasal RAE (Ring, Adaire, Ellwyn) because of the surgical approach, which involves a bicoronal incision.

Patients having Le Fort osteotomies will require a nasal or an oral intubation, depending on the type of Le Fort. Patients having Le Fort I osteotomies (patients with cleft palate or lip) will require a nasal ETT so that the oral cavity can be free of an ETT and thus allow the maxillae and the mandible to be properly aligned. Nasal ETTs have been injured by the surgeons during mobilization of the maxillae during Le Fort osteotomies. This will result in difficulty with ventilation and may require exchanging the ETT ( ). Patients having Le Fort III osteotomies for midface distraction can be intubated orally with an oral RAE. This ETT should be sutured or wired to the dentition of the mandible. Standard tape will often not remain in place during the oral and maxillary manipulations. Unlike patients for cranial vault expansions, patients after Le Fort III midface advancement usually require postoperative intubation. The combination of airway secretions (blood, cerebrospinal fluid [CSF]), edema, and preoperative difficult ventilation (or intubation) may increase the risk of postoperative airway complications.

Some infants with craniofacial anomalies require tracheostomy because of significant upper airway obstruction ( ; ). Adequate preparation entails having all of the necessary equipment available and having personnel that are trained and experienced to use these airway instruments. It may also mean having a pediatric otorhinolaryngologist immediately available.

Intracranial pressure.

Patients with craniosynostosis may develop intracranial hypertension. Typically, this is diagnosed by the presence of papilledema or abnormal VEPs during an ophthalmologic examination. The clinical feature of increased ICP may range from asymptomatic to complaints of visual changes, headaches, somnolence, and vomiting. Children with chronically elevated ICP may be relatively asymptomatic and active. Chronically elevated ICP can have anatomic and physiologic consequences that may affect the surgical and anesthetic management. Computed tomography (CT) scans and magnetic resonance imaging (MRI) will show a copper beaten pot appearance of the skull in patients with chronically elevated ICP. The close proximity of the brain to the skull may make removal of the calvarium difficult. Mannitol 0.25 to 0.75 g/kg and mild hyperventilation may facilitate this process.

Hemodynamic instability can occur in patients with chronically elevated ICP after the calvarium is removed. The likely physiologic cause is the sudden reduction in blood pressure required to maintain cerebral perfusion pressure once the calvarium is removed and the ICP equilibrates with atmospheric pressure. Patients may require transient hemodynamic support with vasoactive medications like epinephrine or phenylephrine.

Blood conservation/transfusion medicine.

Craniofacial procedures are often long and expose infants to the risks of hypovolemia, hypothermia, blood loss, and venous air emboli. One of the most pressing concerns related to the anesthesia care of craniofacial surgery is the management of intraoperative bleeding. The cranial-based procedures can involve significant blood loss because of the duration of the procedure; the exposed skin, bone, and dural surfaces; and the rare complication of entering large vessels like the sagittal sinus. Blood loss during these procedures has remained a constant issue since Dr. Whitaker’s description of perioperative blood loss in 1979 ( ). Blood loss is often as high as half to one blood volume, and nearly 90% to 100% of the infants undergoing these procedures may require a blood transfusion ( ; ; ). In a 2017 review of the Pediatric Craniofacial Database, 91% of infants less than 24 months old required a transfusion, and the average volume of allogeneic blood exposure was 46 mL/kg ( ).

Even the strip craniectomy, which is typically performed to correct nonsyndromic isolated sagittal synostosis and results in less blood loss, can produce significant hemorrhage. In a study by , predictors of blood loss during craniofacial surgery included surgery time longer than 5 hours, age less than 18 months, the presence of multisuture craniosynostosis, and syndromic craniosynostosis. Infants undergoing strip craniectomy usually experience less blood loss, but this population may be at increased risk for transfusion because they present to the operating room at the nadir of their physiologic anemia (2 to 3 months of age). Preparation for these procedures requires a baseline HCT and a type and cross. Some centers will also obtain coagulation studies. Adequate IV access needs to be obtained for resuscitation. In an infant, at least two large-bore (22- to 20-gauge) peripheral IV catheters should be placed to provide adequate access. Arterial pressure monitoring is recommended for beat-to-beat analysis of blood pressure and intravascular volume status in addition for blood gas monitoring. A central venous catheter may be placed for central venous pressure monitoring or in patients with difficult IV access. Although less common, some centers place central venous catheters as part of their craniofacial protocol ( ).

Significant success with minimizing blood loss and exposure to allogeneic blood products during craniofacial surgery has been described by some centers. Surgical techniques that minimize blood loss include using infiltration of subcutaneous epinephrine, needle tip cautery, scalp clips for the scalp flap, bone wax for the osteotomy edges, preoperative erythropoietin, and application of hemostatic agents. Several medical and pharmacologic blood conservation techniques have been described in the older pediatric patient, but less information is available for the infant having cranial vault reconstruction.

Preoperative blood donation has been described in children as small as 8 kg ( ), but there are significant limitations with this technique in the infant. Their young age, small size, and lower HCT may make blood collection more challenging and less feasible. Acute normovolemic hemodilution has been described in older children and adolescents and may be effective. Hemodilution is relatively contraindicated in the infant less than 6 months old. The normal physiologic advantage with hemodilution (increased preload, increased stroke volume, decreased systemic vascular resistance, increased tissue oxygenation) may be lost in the infant because of a naturally less compliant myocardium and fetal hemoglobin, which more avidly binds oxygen.

Because most infants presenting for cranial vault reconstruction have a normal physiologic anemia, erythropoietin was proposed as a therapy to address this concern. Preoperatively, recombinant erythropoietin decreases the transfusion requirements in infants having craniosynostosis repair. reported the dose of erythropoietin as 600 units/kg given subcutaneously once per week along with oral iron supplementation. Erythropoietin was started 3 to 4 weeks before surgery, and the incidence of blood transfusions in infants having craniosynostosis repair decreased from 93% to 57%.

In March 2007 the Food and Drug Administration (FDA) placed a black box warning on synthetic erythropoietin because of the concern of increased death, deep venous thrombosis, and cancer spread in adult patients receiving synthetic Epogen (CHOIR study). These concerns have only occurred in the adult population, but some centers have stopped using synthetic erythropoietin for craniofacial surgery. A multicenter retrospective review of 396 pediatric craniofacial patients receiving erythropoietin did not reveal an increase in perioperative complications, specifically death or deep venous thrombosis ( ).

Antifibrinolytic therapy has been described in pediatric surgery, and now there is both retrospective and prospective evidence of the efficacy of antifibrinolytics in pediatric patients having craniofacial surgery ( ; ; ). Two prospective randomized blinded trials in two different countries demonstrated a significant reduction in allogeneic blood exposure during the intraoperative and postoperative period with the administration of tranexamic acid. In one study the dose administered was 50 mg/kg with 5 mg/kg/hr infusion ( ). In the other study, the loading dose was 15 mg/kg with an infusion of 10 mg/kg/hr ( ). The patients in this study were also coadministered synthetic erythropoietin. Aminocaproic acid was also used, as retrospective data suggest it may also be efficacious ( ). The loading dose for this medication is 100 mg/kg, and the infusion dose is 40 mg/kg/hr infusion ( ). A standard dosing regimen for tranexamic acid and aminocaproic acid is presented in Box 35.1 .

Although efficacy for antifibrinolytics has been demonstrated, safety has not. There are some concerns that antifibrinolytics may increase the risk of thromboembolic complications. In addition, specifically with tranexamic acid, there is concern that the risk of seizures may be increased with intraoperative exposure. There are currently no case reports that describe either of these complications in craniofacial patients. In a review of the Pediatric Craniofacial Database, the incidence of perioperative seizures was 0.6%, and there was no evidence of increased risk of thrombosis or seizures in pediatric patients exposed to tranexamic acid or aminocaproic acid during craniofacial surgery compared with those that did not receive an antifibrinolytic ( ).

In the past, the use of cell saver technology has been reported as being impractical for small pediatric patients because of the size of the collection reservoir ( ). The cell saver reservoirs are currently available in sizes as small as 25 mL. This technology may reduce the rate of autogenous blood transfusion in infants having craniofacial surgery. In fact, the most significant benefit may occur when cell saver technology is combined with erythropoietin pretreatment. In a prospective analysis evaluating the use of cell saver technology with a 55-mL pediatric bowl in patients pretreated with erythropoietin, only 30% of those infants having cranial vault remodeling required allogenic blood ( ). in a prospective randomized trial describe a 5% transfusion rate in infants having elective craniosynostosis surgery when both cell saver technology (25-cc collection reservoir) and erythropoietin are used compared with a 100% transfusion rate in those not receiving cell saver technology or erythropoietin. A relative contraindication for cell salvage use is the coadministration of hemostatic clotting agents like thrombin or Gelfoam. The potential risk of thromboembolic complications may be reduced by administering the blood through a transfusion tubing filter of 20 microns or less ( ).

Despite some of these techniques demonstrating efficacy, many are not used routinely. In a resource utilization survey investigating complex craniofacial reconstruction, erythropoietin, antifibrinolytics, and cell salvage were used in 17%, 30%, and 26% of the centers, respectively ( ). In addition, most centers did not have a designated group of individuals, nor did they have a transfusion protocol. Resource utilization has evolved nationally, and by 2017 antifibrinolytic use increased from 30% to 60%, whereas cell salvage was used in only 10% to 14% and erythropoietin in less than 1% ( ).

Temperature/positioning.

Craniofacial procedures can be very long procedures lasting several hours. Complications resulting from long surgical procedures include skin breakdown, neuropathic injury, and hypothermia. Attention must be paid to the initial setup to ensure adequate positioning and padding to minimize these intraoperative injuries. Infants having posterior cranial vault remodeling may be positioned prone, and attention to protecting the face and eyes is important. Patients with midface hypoplasia and proptosis may present a challenge when placed prone because adequately protecting the face and eyes may be more difficult. One technique to minimize hypothermia is shown in Fig. 35.8 . The infant is placed on a full-access forced hot air blanket to minimize hypothermia, and the surgical site (head) is then isolated from the body using plastic drapes. This not only minimizes convective and radiant heat losses but also prevents conductive heat loss to a wet bed from irrigation and blood. Blood products should be warmed through a fluid warmer prior to administration (except for platelets). IV fluid warmers may be used, particularly if large volumes of crystalloid and cold blood products are being administered. See Chapter 7 : Thermoregulation.