Anaesthesia and craniofacial surgery.SA Karapurkar, MB Garasia, DB Deval
Dept. of Anaesthesiology, KEM Hospital, Bombay, Maharashtra.
Keywords: Anesthesia, methods,Facial Bones, abnormalities,surgery,Human, Intraoperative Complications, Monitoring, Intraoperative, Patient Selection, Postoperative Complications, Skull, abnormalities,surgery,
Craniofacial surgery can be defined as the surgical correction of disorders affecting the skull base, orbits and upper face. Until recently, this complex anatomical territory fell into "no man's land", with several major surgical specialities performing part of the surgery but no single speciality was able to provide a comprehensive surgical correction for the patient. So results were poor and the morbidity and mortality was high.
In 1965, Dr. Paul Tessier, pioneered a multidisciplinary team approach. The teams were composed of plastic surgeon, neurosurgeon, maxillofacial surgeon, ENT surgeon, ophthalmic surgeon and anaesthetists who worked together to manage the complex problems.
The anaesthetist is an important member of this team who should be aware of the complexity of the surgery and be able to recognise and manage problems that may arise during the procedure.
Patients having craniofacial (CF) deformity are operated in childhood. With the overall improvement in anaesthesia techniques, availability of newer anaesthetic drugs and monitors, paediatric anaesthesia has become safe even for prolonged surgery. CF surgery is one of the best examples of management of a prolonged procedure on a paediatric patient with the anaesthesia time lasting as long as 24 hours.
In India very few centres practise this form of surgery. At our Institution, such surgery was started from 1982, with the active participation of the plastic surgeon, neurosurgeon and anaesthetist.
Steward has classified these anomalies into six groups:
I. Otocranial facial syndromes with bilateral symmetrical involvement ( Treacher Collins syndrome More Detailss).
II. Otocranial facial syndromes with asymmetric involvement (Goldenhaar's syndrome, hemifacial microsomia).
III. Craniosynostosis with craniofacial synostosis.
IV. Midface abnormalities (cleft lip and palate).
V. Frontonasal dysplasia (hypertelorism).
VI. Craniofacial clefts, which may be associated with an encephalocele.
Groups I, II and IV are associated with serious airway problems including intubation difficulty. Premature fusion of one or more sutures results in craniosynostosis. Approximately 1: 2000 children suffer from premature fusion of cranial sutures.
If one suture is involved, compensatory growth occurs at the unfused sutures. In those having a deformity of the cranium without intracranial hypertension, surgery is purely cosmetic and elective. In those with multiple suture fusion, there is a raised intracranial pressure (ICP) and surgery is a must.
Craniectomy or remodelling of the skull should be performed early to obtain good results. In this Institution, operations are carried out at 5 months of age even if the baby presents in the neonatal period, or at any age at which the patient may present. Multi suture involvement reduces the intracranial volume and leads to rise in ICP, which hampers brain growth and development.
Premature fusion may affect the base of the skull and face causing maxillary hypoplasia with partial airway obstruction -craniofacial synostosis. If not treated early, it can lead to raised ICP and hypoplastic maxilla, which in turn leads to proptosis. If proptosis is severe, corneal ulceration can occur.
Sometimes, this anomaly is associated with various syndromes. The most common are Crouzon's syndrome and Apert's syndrome. Pfeiffers, Saethre Chotzen's and Carpenter's syndromes are rare. Hence, the main indications for surgery are raised ICP, cornea exposure and ulceration, airway difficulties and dental malocclusion. Since some associated anomalies directly affect anaesthesia, anaesthetists should be aware of them and subsequent problems arising after surgery.
In last 11 years, we have performed surgery in 97 cases with good results. Anaesthesia time has ranged from 6 hours to 20 hours.
Preoperative assessment of these patients is very important. Apart from a routine check-up, special attention should be given to assessment of the airway. Noisy, disturbed steep indicates partial airway obstruction, which is fairly common in these patients. They are prone to respiratory depression during anaesthesia. One must rule out other associated anomalies like CHD, choanal atresia, high arched palate, Klippel Fell abnormality or atlantoaxial dislocation. Difficult intubation must be anticipated in all these patients. All these children are prone to repeated upper respiratory tract infection due to choanal atresia or hypersalivation. They require adequate antibiotic cover. Anticonvulsants should be started 4-5 days prior to surgery.
In the 97 patients operated, the following associated anomalies were found
Cleft lip and palate- 3
Hydrocephalus- 4 (shunt was done)
Choanal atresia- 2
Apert's syndrome- 8
Crouzon's syndrome- 12
Pfeiffer's syndrome- 1
Carpenter's syndrome- 1
Atlantoaxial dislocation- 20
A complete blood count is performed. A haemoglobin level in excess of 10 g% (PCV 35) is essential. Bleeding and clotting times should be done, since there is continuous ooze of blood from the cut edges of the bone during surgery. Serum electrolytes and blood urea should be done as patients receive higher antibiotics preoperatively and osmotic/loop diuretics to reduce ICP. X-ray chest is necessary to find out abnormal heart shadow and lung field. X-ray cervical spine-AP and lateral are done to rule out fusion/atlantoaxial dislocation of spine. CT scan of head is done to know the exact position of sutures. Blood is always grouped and cross-matched. At least 3 units of fresh blood are kept ready.
Anaesthesia for CF surgery is a challenge to anaesthetists. These children are kept nil by mouth from 4 a.m. Because of airway problems, sedatives should be used carefully to avoid further obstruction and increase in ICP. Mild tranquilliser like thmeprazine is advised in older children. We prefer to give intraoperative IN. diazepam 0.2 mg/kg and pentazocine 0.3 mg/kg. Inj. atropine 0.02 mg/kg LM should be given preoperatively. Very often due to choanal atresia, these patients have profuse secretions, which can cause blockage of ETT intraoperatively. Repeated endotracheal suction may not be possible due to surgical drapes and position.
Irrespective of cervical spine pathology, one should anticipate difficult intubation. Laryngoscopes of various sizes should be kept ready. Fibreoptic laryngoscope is ideal. Patient is kept in supine position with 10-15? head up. These patients are always intubated with flexometallic tube. An oral RAE or portex polar 'South' tube will be satisfactory for the procedures above infraorbital margin. The flexometallic tube is kept in position by packing the throat with roller gauze. It also helps in preventing blood trickling into the respiratory tract when frontal craniotomy is done. Fixation of ETT is very important since access to airway is very limited. Usually it is done by taking a stitch on the chin or fixing it to teeth with k-wire.
One must observe the basic principles of neuroanaesthesia for these procedures. Every effort should be taken to reduce ICP so that less brain retraction will be required during the surgery. This helps in preventing postoperative brain oedema.
All volatile anaesthetic agents cause cerebral vasodilatation and should be avoided. We induce all infants with inhalational technique as to get a good vein in an awake baby is very difficult. Older children are induced with I.V. Sodium Pentothal. Anaesthesia is maintained with nitrous oxide, oxygen and nondepolarising muscle relaxant.
Isollurane is the anaesthetic agent of choice, since it causes least rise in CBF. Blood volume within the cranium is reduced by controlled hyperventilation during the procedure. Cerebral blood vessels are very sensitive to CO2 tension in arterial blood. For each 1 kPa reduction in PaCO2, 15% CBF is decreased.
If the baby is having raised ICP, 20% mannitol or dexamethasone is given in the early part of surgery. The surgeon is also asked to drain CSF by ventricle puncture or opening the subarachnoid space because we want rapid return of reflexes at the conclusion of surgery, opioids are not used for these patients.
Two intravenous lines with no. 20 and 22 cannulae are essential. They are well secured and easily accessible intraoperatively. Through one route 5% Dextrose or Pedilyte is infused as per patient's caloric requirements. The other route is kept for colloids or blood transfusion.
Blood loss: Blood loss is a major problem in this surgery. Continuous ooze, concealed blood under the drapes and saline used for irrigation, make it difficult to judge exact blood loss. At least 2 units of fresh blood and fresh frozen plasma (FFP) should be kept ready.
One of our patients had received a 3 weeks old blood unit during surgery. Postoperative period showed normal haematocrit but due to poor oxygen carrying capacity, there was anoxia and hyperventilation. It responded well to O2 tent. Blood loss ran be reduced by proper ventilation, use of saline infiltration with adrenaline/ vasopressin. We found vasopressin is better than adrenaline. It has less effect on heart rate.
Children are known to be resistant to hypotensive drugs. The tachycardia, which they get early, makes the hypotensive technique unsuccessful. Ten percent of the estimated blood volume is usually infused as blood prior to the incision. In western countries these children are preloaded with warmed 4.5% human albumin solution.
Heat loss: Due to poor insulation and loss of heat conserving mechanism under general anaesthesia, hypothermia is very common in children. Air-conditioned operation rooms and prolonged surgery add to it. We lost one baby due to deep hypothermia. Baby remained in urine soaked bed-sheet for several hours intraoperatively which resulted in hypothermia.
Our patients are protected by wrapping cotton gamgees around extremities and chest, covering with electric blanket, use of plastic drapes, focusing overhead radiant heater and placement of urinary catheter. Even anaesthetic gases are humidified intraoperatively.
Bradycardia: During orbital correction, sinus bradycardia can occur due to pressure on eyeball. Monitoring of these patients on cardioscope for early detection of arrhythmia is needed.
Air embolism: It is a potential hazard during cranial surgery. End tidal CO, (ETCO) and precordial/ oesophageal stethoscope are used intraoperatively.
Back in 1912, a surgeon had stated, that any operation more than 15 minutes long in a child was doomed to failure. With improvement in paediatric anaesthesia and various monitors, surgeons can operate on a child for any length of time.
At our centre, all patients are monitored on cardioscope. Blood loss is a major problem. Therefore direct measurement of arterial pressure is done. Continuous display of ETCO2, oxygen saturation makes the anaesthesia safe in prolonged surgery. Precordial stethoscope is fixed for detection of air-embolism and change in breath sounds. Core temperature is monitored to prevent hypothermia. All children are catheterised preoperatively to monitor hourly urine output and hydration. This also helps to prevent hypothermia. Central venous catheterisation is not necessary in younger children as it has its hazards.
Accidental extubation- 1
Massive blood loss (> TBV)- 3
Immediate postoperative period is very important. Airway is always compromised by swelling around the upper airway and larynx. Persistent bleeding from nose and midface, can accumulate in the throat and can cause obstruction or aspiration. Hence at the end of surgery, patient should be fully conscious with all reflexes present.
In case of doubt, extubation can be delayed. Frequent checking of patency of ETT, in postoperative period is essential. We lost one baby due to blockage of ETT.
Drainage: Monitoring of slow blood loss through scalp drain is important to prevent hypotension. Significant loss should be replaced.
Analgesia: CF surgery is an extensive surgery. Patients need good analgesia postoperatively. But these drugs should be used sparingly as there is high risk of respiratory depression. Such patients should be closely observed. In older children Inj. pentazocine 0.5 mg/kg I.M. is given while infants are comfortable with parents.
Laryngeal oedema- 3Infection- 1
Tracheostomy- 1Hypothermia- 1
Ventilatory support- 1Convulsions- 1
Reintubation- 1Massive blood
ETT blockage- 1
CF surgery is as yet something new in India. It presents many challenges to anaesthetists. When it started in our institute in 1982, it was a great problem to surgeon and anaesthetist to handle these small children for long duration of anaesthesia, surgery and to replace the massive blood loss (Sometimes more than the total blood volume). But as the team has gained experience, duration of surgery and blood loss has been drastically reduced, and the results are encouraging now.
Results will still improve if following things are available:
1. Fibreoptic laryngoscope for difficult airway cases.
2. 4.5% Human albumin solution instead of crystalloid.
3. Facilities to do arterial blood gas and electrolytes so early correction of metabolic status if required.
4. Availability of haematocrit and clotting profile intra and postoperatively to detect dilutional coagulopathy.
5. Good intensive care unit.
By paying meticulous attention to details, anaesthetists make a valuable contribution to the surgical outcome.