AIRWAY MANAGEMENT IN NEUROSURGICAL PATIENTS

Transcription

1 336 Indian J. PG Anaesth. ISSUE 2005; : AIRWAY 49 (4) : MANAGEMENT INDIAN JOURNAL OF ANAESTHESIA, AUGUST AIRWAY MANAGEMENT IN NEUROSURGICAL PATIENTS Dr. Umamaheswara Rao G. S. Indroduction Special attention to airway is necessary in neurosurgical patients for many reasons. Procedures used for airway maintenance may worsen the spinal instability in patients with traumatic, congenital or degenerative cervical lesions. The ischemic or injured brain tolerates hypoxia very poorly. Hypoxia at the time of admission is associated with a significant decrease in favorable outcome in traumatic brain injury. Manoeuvres used to secure airway may aggravate intracranial hypertension in patients with traumatic brain injury. Routine intraoperative airway management may be complicated by the complex requirements of positioning and preoperative intracranial hypertension. Diseases of the pituitary gland associated with acromegaly may present special problems in the airway management. The current review attempts to discuss the airway management in neurosurgical patients under the following headings: 1. Airway management in diseases of the cervical spine 2. Airway management in head injury 3. Airway management in acromegaly 4. Endotracheal intubation for elective craniotomy Airway management in diseases of the cervical spine Congenital or acquired lesions associated with cervical spinal instability may pose challenges in the airway management. Efforts to secure airway in these patients may worsen the subluxation leading to aggravation of the neurological deficits. Cervical spine trauma Cervical spinal injuries occur in 2-5% of blunt trauma. In 7-14% of cases, these lesions are unstable. In the National Emergency X-Radiography Utilization Study (NEXUS) that enrolled 34,069 patients of blunt trauma, patients sustained 1193 fractures and 231 subluxations. The most common level of the fracture was C-2 (24% of fractures). Dislocations occurred most commonly at C-5/6 and C-6/7 levels. The incidence of Professor of Neuroanaesthesia National Institute of Mental Health and Neurosciences Bangalore gsuma@nimhans.kar.nic.in, gsuma123@yahoo.com missed or delayed diagnosis of cervical spine lesions was 1-5%, with up to 30% of such patients developing secondary neurological damage. In yet another earlier series, secondary neurological damage occurred in 10.5% of patients with a missed diagnosis of cervical spine fractures. 2 Assessment of cervical spinal stability prior to airway manoeuvers Despite liberal use of cervical spine x-rays in trauma, the majority of them are normal. In order to avoid unwanted radiographs, five clinical criteria have been used to clear cervical spine in conscious trauma patients. 3 These criteria are: a) no posterior midline cervical spine tenderness, (b) no intoxication, (c) alert patient, (d) no focal neurological deficits and (e) no painful distracting injuries. The overall sensitivity of these criteria for identification of any type of cervical spine injury is 97.6% and 99% for significant injury. The criteria, however, have a low specificity. Conscious patients who do not satisfy the above criteria must be investigated by three cervical radiographs namely, lateral view including the base of the occiput to first thoracic vertebra, anteroposterior view and open mouth odontoid view to rule out injury to the cervical spine. In patients with altered mental status, there is no consensus on the criteria for cervical spine clearance. It is a common practice to rule out injury to cervical spine by a lateral radiograph. The NEXUS database however has shown that even screening radiography using three cervical views can identify only 61% of the injuries. 4 Computed tomography with 3 mm slices using helical scanning and multiplanar reconstruction has been shown to have a much higher sensitivity of %. Instability of the cervical spine caused by injuries to ligaments may not be detected by plain radiography. Ten percent of patients with cervical spine injuries and 0.2% of all patients with blunt trauma have unstable cervical spine without fractures that are detected by a combination of plain radiography and selective computed tomography. 5 In conscious patients, ligament injuries present as neck pain and tenderness. Elimination of ligament injury is difficult in unconscious patients. The options that the clinicians may have in unconscious patients with ligamentous injuries are: a) leave the cervical spine uncleared and maintain stabilization until the patient becomes conscious, (b) review three cervical radiographs

2 UMAMAHESWARA : AIRWAY MANAGEMENT IN NS PATIENTS 337 supplemented within axial CT images with reconstruction through the suspicious areas (c) assess the stability of cervical spine by flexion/extension fluoroscopy, or (d) perform magnetic resonance imaging of the cervical spine. Spinal cord injury may occur without any radiological abnormality in % of all spinal injuries. 4,5 MRI is the investigation of choice to detect this condition. Airway management in patients with spinal injury The objective during airway management of patient with cervical spine injury is to secure the airway rapidly and efficiently with minimal or no movement of the neck. Videofluoroscopic studies in anaesthetized patients and cadaver models of cervical spine injury have improved our understanding of the movement of spine during intubation in normal individuals and in patients with spinal cord injury. Effect of basic airway manoeuvers on cervical spine mobility Chin lift and jaw thrust in an adult cadaver model of C5-6 ligamentous injury caused a greater than 5 mm increase in the disc space. 6 This widening was not prevented by a Philadelphia collar. Introduction of an oesophageal obturator airway caused a 3-4 mm increase in disc space. Anterior neck pressure to facilitate nasotracheal intubation caused a posterior subluxation of more than 5 mm. Head tilt, and insertion of an oropharyngal or nasopharyngeal airway are not associated with any significant displacement of the spinal segments. Cricoid pressure applied during emergency intubation has been generally believed to displace the spine. But a recent cadaver study using a lateral cervical spine x-ray showed negligible spine movement with cricoid pressure. 7 Effect of spinal Immobilisation on techniques of airway management Maneuvers used for spinal immobilization may restrict the exposure of larynx during laryngoscopy. Immobilisation of neck with collars, straps and sand bags restricted the mouth opening and caused a poor laryngoscopic view (grade 3 and 4) in 64% of the patients. 8 Visualisation improved with manual inline traction but was still poorer compared to the view in the optimal intubating positioning. Manual inline stabilization decreases, but does not completely eliminate cervical spine movement during laryngoscopy. 9 Axial traction applied through weights or by an assistant, as it has been advocated earlier, can be deleterious. In patients with unstable cervical spine fractures, axial traction has been shown to cause a mean distraction at the fracture site of 7.75 mm. 10 Therefore, the current emphasis during intubation of a patient with an unstable cervical spine is on manual inline stabilization and not axial traction. Techniques of securing airway in patients with cervical spine injury Direct Laryngoscopic Intubation: Direct laryngoscopic orotracheal intubation with manual inline neck stabilization is the most commonly recommended technique for securing airway in a patient with cervical spine injury. During normal direct laryngoscopy and oral intubation, significant extension occurs between occipital bone and C1 and also between C-1 and C-2. 11,12 Manual inline neck stabilization reduces this head extension by 50% in anaesthetized patients. 13 However, in a cadaver study of injuries at C4, this type of stabilisation did not reduce the movement, suggesting the limitation of this manoeuver in preventing movement of the spine in patients with cervical spine injury. 11 Axial traction on spine should be avoided during laryngoscopy and intubation as this could increase the spinal cord injury. As discussed above, laryngoscopic view is difficult if a cervical collar is left in place during intubation. 8 Gum elastic bougie is an important adjunct for direct laryngoscopic intubation. By using a bougie, the laryngoscopist tends to use less pressure, thereby potentially avoiding a displacement of the fractured spine. 14 Influence of the type of laryngoscope on cervical movement: The cervical spine movement caused by McIntosh curved blade or Miller s straight blade are not significantly different during direct laryngoscpic intubation. 15 In a comparison of McIntosh and McCoy laryngoscopes, McCoy laryngoscope improved visualization of the larynx by at least one grade in 49% of cases. 16 In another study, Miller and McIntosh blades were compared with Bullard laryngoscope. 17 Head extension and neck movements were less and laryngeal visualization better with Bullard laryngoscope. However, there were problems associated with Bullard laryngoscope, which included prolonged time for intubation, fogging, and occasional inability to pass the tracheal tube through the glottis. Angulated video intubating laryngoscope significantly improved the laryngeal view compared with direct laryngoscopy with cricoid pressure. 18 Awake Intubation: Awake intubation is considered safe in a patient with spinal injury as the normal muscle tone provides protection and the neurological status of the patient can be monitored. The various options available for

3 338 PG ISSUE : AIRWAY MANAGEMENT INDIAN JOURNAL OF ANAESTHESIA, AUGUST 2005 awake intubation are awake oral or nasal intubation and awake fibreoptic intubation. Despite the safety claimed for awake intubation, a number of limitations of these techniques must be appreciated. Awake intubation is slower compared to rapid sequence intubation. Cooperation from the patient is very essential for the success of the procedure. Considerable expertise of the operator is required to accomplish awake intubation. Blind nasal intubation is complicated by epistaxis, laryngospasm and oesophageal intubation. In cadavers with a C-5/6 instability, blind nasal intubation caused least cervical spine movements. 19 With C-1/2 instability both oral and nasal intubations produced similar cervical spine movement. 20 In cadavers with C-3 injury, awake fibreoptic technique produced no movement of unstable segments as assessed by video fluoroscopy. 21 Laryngeal Mask Airway: Laryngeal mask airway (LMA) is a widely accepted device in cases of difficult intubation. LMA can be easily inserted in a neutral position and hence considered ideal for use in patients with unstable cervical spine. 22 Though there is a risk of aspiration with LMA, it seems to have been overstated. Intubating LMA has been used successfully for blind intubation in patients undergoing cervical spine surgery. 23 It has also been used in conjunction with rapid sequence intubation and also for awake oral intubation with fibreoptic bronchoscope. 24 Both standard LMA and intubating LMA have been shown to cause a temporary pressure of 250 cm H 2 O against the posterior pharyngeal wall during insertion. The pressure is sufficient to cause up to 2 mm of displacement of C3. 25 The cervical spine movement that occurs during insertion of LMA and intubation through LMA is less than that produced during direct laryngoscopy. 26 Neck stabilization techniques and cricoid pressure may make insertion of LMA more difficult. 27 Cricoid pressure applied after the insertion of intubating LMA makes the passage of the tracheal tube more difficult. 28 Augustine Device: Augustine s device, an accessory to blind oral intubation has been compared with direct laryngoscopy in 16 patients. Augustine s device caused a 17 less extension from occiput to C Surgical Airway : Cricothyroidotomy, which is attempted when non-surgical techniques of securing airway have failed may be associated with movement of cervical spine. In a cadaver model of C-5/6 transection, cricothyriodotomy resulted in 1-2 mm anteroposterior displacement and 1 mm axial compression of the spinal cord. 30 A plan for airway management in a patient with cervical spine injury From the foregoing discussion it follows that a careful plan for selection of the technique and the devices is necessary for securing airway in a patient with unstable cervical spine. Urgency of intubation, presence of other associated head and facial injuries, presence of basilar skull fractures, patient cooperation, intoxication of the patient due to alcohol or drugs and the expertise of the operator are some of the factors to be considered in the initial airway management of a patient with cervical spine injury. Direct laryngo scopy Radiologic spine evaluation Apnea/Respiratory Distress Assess Airway and Oxygenation Intubation in most efficient manner Inline stabilization without axial traction Yes Emergency Airway Airway secured No Mask ventilation * Oral/nasal airway * Avoid jaw thrust/ neck movement ASA Difficult Airway Algorithm Jet vnetilation Cricothyrotomy LMA Tracheostomy Adequate Elective Airway Cervical spine x-ray series * CT Scan * MRI * Special views Normal Cautious oral/nasal intubation Results Abnormal Nasal Intubation Awake fiberoptic Surgical airway Fig. 1 : An algorithm for airway management in a patient with suspected cervical spine injury Abnormal Airway Awake Intubation Blind Technique Or Fibreoptic Failure Cricothyrotomy Retrograde Intubation Normal Airway Cervical Spine Not Clear Same as normal Airway except Head held in neutral position Haemo Dynamically Stable Reduce ICP Thiopentone Lignocaine Prevent Cough Suxameth Defasciculate Crocoid press Ventilate Prevent Hyperten. Narcotics Esmolol Labetalol Normal Airway Normal Cervical Spine Possibly Hypovolemic Reduce ICP Etomidate Lignocaine Prevent Cough Suxameth Defasciculate Crocoid press Ventilate Haemo Dynamically Unstable Prevent Cough Suxameth Defasciculate Crocoid press Ventilate Fig. 2 : An algorithm for airway management in a patient with head injury In a retrospective analysis of 393 patients with cervical spinal injury, 104 required intubation; the techniques of intubation used in these patients comprised of oral or nasal intubation with direct laryngoscopy under general or local anaesthesia in 93 patients and intubation with a

4 UMAMAHESWARA : AIRWAY MANAGEMENT IN NS PATIENTS 339 fibreoptic scope in 11 patients. Irrespective of the technique used, there were no instances of neurological deterioration attributable to endotracheal intubations. 31 Absence of a major effect of the technique of intubation on neurological outcome has also been documented in another study of 150 patients undergoing elective spinal stabilization. Intubation was carried out in an awake state or under general anaesthesia. The techniques of intubation consisted of direct laryngoscopy, blind nasal intubation, fibreoptic intubation or intubation with the aid of lighted stylet in both the groups. 32 As can be inferred from the above evidence, emphasis during the airway care of a patient with cervical spinal injury is not on the specific technique of management, but on operator experience and case-specific management. No single technique of airway management has been shown to be superior to others. 33,34 Bag mask ventilation, introduction of oral or nasal airway, chin lift, jaw thrust and oral or nasal intubation may be required based on the needs of the individual patients. Despite the fact that all these maneuvers have the potential to move the cervical spine, excessive attention to immobilization techniques is undesirable as it may delay the airway management or make intubation difficult; eventually it may lead to inadequate ventilation. There is no evidence for an association between the technique of intubation and neurological deterioration when manual inline stabilization is ensured. Therefore, the fear of inflicting cord damage should not prevent securing the airway with the technique that the operator is conversant with. A practical approach for airway management in a patient with suspected cervical spine/ injury is shown in figure 1. If the patient is apneic, rapid orotracheal intubation by direct laryngoscopy must be achieved while manual inline stabilization is maintained. If this approach is impossible due to extensive faciomaxillary injuries, surgical airway must be attempted. If no immediate need for airway exists, a detailed radiological evaluation can be carried out. If the evaluation is positive/possible for cervical spine injury, and the patient is cooperative and requires a non-emergent intubation, awake fibreoptic intubation under local anaesthesia may be carried out. Awake nasotracheal intubation or surgical airway are the other alternative choices. Congenital anomalies of the cervical spine Failure of fusion of the bony structures, laxity of the ligamentous structures or excess ossification of the spine are the causes of congenital spinal anomalies that may interfere with safe tracheal intubation. Hypoplasia of the odontoid may occur in isolation or as a part of many clinical syndromes such as Morquio s syndrome, Klippel- Feil syndrome, Down s syndrome, and Osteogenesis imperfecta. In these patients, hyperextension of the atlantoaxial joint during tracheal intubation may cause subluxation of atlas over axis thereby reducing the spinal canal space and compression of the cervical cord. Laxity of transverse ligament is seen in 14-22% of children with Down s syndrome. 35 Extension of head in these patients may cause subluxation of atlas over axis with resultant compression of the spinal cord by the odontoid process. Rotatory subluxation of the atlanto-axial joint and posterior subluxation of the axis have been reported in the postoperative period in patients with Down s syndrome. 36,37 Increased prevalence of lower cervical spondylosis and cervical myelopathy are known to occur in adults with Down s syndrome. Other spinal anomalies with specific relevance to airway management seen in patients with Down s syndrome include spina bifida of the atlas, vertebral occipitalisation, congenital nonunion of the odontoid process and Klippel-Feil syndrome. The importance of all the above anomalies lies in the fact that tracheal intubation may be rendered difficult in these patients. Also, cervical spinal movements during intubation may worsen the spinal cord compression. Awake fibreoptic intubation under regional anaesthesia is preferred in these patients. Anaesthetic drugs should not be administered until the trachea is intubated, patient is positioned for surgery and neurological examination carried out. Airway management in head injury Patients with severe traumatic brain injury require endotracheal intubation in the emergency room. Uncooperative head injured patients may require sedation for computed tomographic scanning and sedatives cannot be administered without an endotracheal tube in place and institution of controlled ventilation. All head-injured patients should be assumed to have an unstable spine until proven otherwise and precautions described in the section on cervical spinal injuries should be followed meticulously. The major goals during intubation of a braininjured patient are to prevent an increase in intracranial pressure (ICP), prevent pulmonary aspiration and avoid aggravation of a coexisting spinal injury. All these objectives are satisfied by a rapid sequence induction with thiopentone or propofol and suxamethonium and intubation while maintaining cricoid pressure and manual inline axial stabilization. But a number of limitations of this approach need to be appreciated. If the airway is difficult, hypnotics and muscle relaxants are contraindicated unless the ability to ventilate with a bag and mask has been

5 340 PG ISSUE : AIRWAY MANAGEMENT INDIAN JOURNAL OF ANAESTHESIA, AUGUST 2005 established. Administration of thiopentone or propofol in a hypovolemic patient may decrease the systemic arterial pressure and thereby the cerebral perfusion pressure (CPP). A profound decrease in CPP caused by the anaesthetic agents may be more detrimental to cerebral oxygenation than a transient increase in ICP caused by intubation. It is very well established now that cerebral blood flow in a patient with traumatic brain injury is lowest duirng the first 24 after injury, which is precisely the time when he is most likely to require emergency endotracheal intubation. There is no consensus on the choice of agent for reducing ICP during tracheal intubation in a patient with traumatic brain injury. Based on the evidence from studies on tracheal suctioning, it is generally believed that lignocaine is effective in preventing a rise in ICP. There is however, no substantial evidence to support this belief. In fact, even in studies on tracheal suction, prevention of cough by a muscle relaxant seems to be more effective in decreasing the ICP than administering other adjuvants such as thiopentone, fentanyl or Lidocaine. 38 Barbiturates and lidocaine were, however, effective in attenuating ICP increase caused by tracheal suctioning in patients who have already received muscle relaxants. Choice of relaxant for intubation also remains somewhat controversial. Suxamethonium causes a transient increase in ICP by stimulating the brain through muscle fasciculation. Defasciculation with a small dose of nondepolariser muscle relaxant appears to prevent an increase in ICP. Agents such as thiopentone, propofol or lignocaine may also minimize the effect of suxamethonium. Rocuronium, which has an onset of action that is close to that of suxamethonium could have been an ideal nondepolariser muscle relaxant for rapid sequence intubation. But its long duration of action makes it unsuitable and positively risky in patients with difficult airway. Inability to intubate rapidly or ventilate adequately after administration of the relaxant may aggravate the cerebral injury. Thus, despite its potential to increase ICP transiently, suxamethonium remains the relaxant of choice for rapid intubation and institution of mechanical ventilation in a head injured patient. Hyperkalemic response to suxamethonium may be expected from 48 hours onwards with peaks between 4 weeks and 5 months. A practical approach to endotracheal intubation based on an assessment of airway and haemodynamic status of the patient is shown in figure 2. In a patient with head injury, the decision to extubate or decannuate the trachea must take into account the Glasgow coma score of the patient and his ability to maintain an unobstructed airway. The patient must be capable of clearing his airway secretions before extubation is attempted. Patients with a Glasgow coma score of eight or less are unlikely to tolerate extubation. Postextubation monitoring in these patients should include the level of consciousness in addition to the routine cardiorespiratory variables. Any neurological deterioration during weaning which is otherwise unexplained, should be considered an indication for reintubation. Problems may be encountered during extubation or decannulation of head injured patients who have required an artificial airway for a prolonged period of time. The ideal time for tracheostomy in such patients remains debatable. Endotracheal tubes made of polyvinyl chloride may be generally left in situ for upto two weeks. Repeated coughing on the endotracheal tube could lead to significant laryngeal injury and postextubation laryngeal oedema. Stenosis at the glottic and subglottic levels may occur in such patients, if a tracheostomy is performed after a prolonged period of intubation. This, in turn, may lead to difficulties in decannulating the trachea. Therefore, early tracheostomy at the end of the first week should be considered in a patient whose trachea is unlikely to be extubated by two weeks and the patient s airway reflexes are active. These problems are even more accentuated in children in whom the airway is already narrow. Airway management in acromegaly Airway management may be difficult in a patient with acromegaly due to hypertrophy of facial bones and mandible, large bulbous nose, thick tongue and lips, and hypertrophy of the nasal turbinates, soft palate, tonsils, epiglottis and larynx. Mask fit and laryngeal visualization may be difficult in these patients. Glottic stenosis due to tissue overgrowth may predispose to preoperative hoarseness and dyspnoea; it may also cause post-extubation oedema. Unusual cases of pituitary adenomas with nasal and nasopharyngeal extension that caused airway problems have been reported. 39,40 Vocal cord paralysis may result from stretching of recurrent laryngeal nerve, impaired mobility of cricoarytenoid joints, or compression of recurrent laryngeal nerve by thyroid enlargement. Acromegalic patients also have a higher incidence of preoperative hypertension and cardiomegaly. The combination of a difficult airway with cardiac disease may predispose these patients to major haemodynamic disturbances at intubation. Sleep-disordered breathing, either central or obstructive in nature, is common in patients with

6 UMAMAHESWARA : AIRWAY MANAGEMENT IN NS PATIENTS 341 acromegaly. The pharyngeal airway of acromegalic patients with sleep-disordered breathing is highly collapsible. The etiology of sleep-disordered breathing in acromegaly appears to differ from that of ordinary sleep apnea. Anatomic abnormality, especially at the base of the tongue, appears to play a significant role in development of this problem. 41 A thorough preoperative airway evaluation is mandatory in these patients. Patients without hoarseness, dyspnea or other acromegalic stigmata may be managed in a routine manner. Those with glottic anomalies should be intubated with a fibreoptic laryngoscope, awake or anaesthetized depending on the degree of laryngeal involvement evaluated by indirect laryngoscopy. Nasal intubation cannot be considered for transphenoidal surgery as it would obstruct the surgical field. In a study of 28 patients with acromegaly compared with 28 matched controls, difficult intubation was encountered in 12 patients in the acromegalic group and 1 patient in the control group; 19 patients in the acromegalic group had enlarged tongue; three patients in the acromegalic group and none in the control group required fiberoptic intubation. 42 Intubating laryngeal mask airway has been used as a primary tool for ventilation and intubation in acromegalic patients. In one study of 23 patients with acromegaly, intubating laryngeal mask airway was successful as a primary airway for oxygenation and ventilation before attempting intubation. Intubating laryngeal mask airway could be successfully placed at the first attempt in 91% of patients and in the second attempt in the rest. An attempt at tracheal intubation through the intubating laryngeal mask airway was successful only in 82% of the patients. The study concluded that intubating laryngeal mask airway can be used as a primary airway for oxygenation in acromegalic patients but the rate of failed blind intubation through the intubating laryngeal mask airway precludes its use as a first choice for elective airway management. 43 Rhinological problems may occur after a trans-septal transphenoidal surgery for pituitary tumors. Endoscopic observation of the nasal cavity after a transphenoidal surgery may reveal the presence of crust formation, hypertrophy of the inferior turbinate, or synaechiae. All the above changes have been shown to increase the resistance to airflow following transphenoidal surgery. 44 Endotracheal intubation for elective craniotomy Surgical position and aggravation of intracranial hypertension are two major considerations in the airway management for an elective craniotomy. Surgical position and airway Airway compromise may be expected in some of the positions used for neurosurgery. Flexion of the neck is generally required for approach to lesions in the infratentorial compartment and high parietal region. Lateral position or park bench position are required for lateral cerebellar and cerebellopontine angle lesions. Prone position is generally used for surgery on cerebellar lesions and spinal lesions. There is a risk of kinking of the endotracheal tube or inadvertent extubation in all these positions. Flexion of the neck after intubation may lead to endobronchial migration of the tube. In all these patients, adequacy of ventilation must be confirmed after surgical positioning. Reinforced endotracheal tubes should be used where there is a risk of kinking of the endotracheal tube. There are reports of obstruction of a reinforced endotracheal tube through a valve-like mechanism caused by a partial detachment of the inner coating from the embedded spiral of the ETT. The detachment was most likely caused by reuse of a single-use product after autoclaving. 45 Continuous soaking of the tapes used for tracheal tube fixation by saliva might increase the risk of self-extubation. Massive oedema of the tongue and face requiring postoperative tracheal intubation for many days has been reported following posterior fossa surgery in sitting as well as lateral positions. The exact mechanism of the complication remains ill-understood. 46 Pressure on endotracheal tube might be caused by the instruments used in anterior surgical approaches on the cervical spine. An armored endotracheal tube prevents airway compromise in these situations. Postoperative airway oedema may occur following high cervical spine surgery or skull base surgery requiring extensive dissection. Intracranial hypertension and airway management for craniotomy No specific measures other than those required for any routine endotracheal intubation are necessary in patients without evidence of raised ICP. In patients with evidence of raised ICP, acute exacerbation of intracranial hypertension should be avoided. A smooth and unhurried intubation is very essential. The dosage of the hypnotic used for induction should ensure adequate depth of anaesthesia at intubation. Profound muscle relaxation must be achieved with a non-deplorising muscle relaxant before intubation. An additional dose of thiopentone or propofol may be given just prior to intubation. Lignocaine in a dose of 1-2 mgkg -1 is administered intravenously to prevent a rise in ICP. Mild hyperventilation by mask before intubation and also after intubation may also help to reduce ICP. Hypercapnia at this stage may be meticulously avoided by continuous capnographic monitoring.

7 342 PG ISSUE : AIRWAY MANAGEMENT INDIAN JOURNAL OF ANAESTHESIA, AUGUST 2005 In summary, airway management plays a critical role in the acute management of neurosurgical patients. The primary neurological problem may pose limitations on the techniques used for establishing an unobstructed airway. At the same time, inadequate airway management may adversely affect the neurological outcome of the patient. A clear understanding of this interaction in a given patient helps to determine the choice of appropriate airway maintenance technique in that patient. References 1. Goldberg W, Mueller C, Panacek E, Tigges S, Hoffman JR, Mower WR. Distribution and patterns of blunt traumatic cervical spine injury. Ann Emerg Med 2001; 38: Reid DC, Henderson R, Saboe L, Miller JD. Etiology and clinical course of missed spine fractures. J Trauma. 1987; 27: Hoffman JR, Mower WR, Wolfson AB, Todd KH, Zucker MI. Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. National Emergency X-Radiography Utilization Study Group. New Engl J Med 2000; 343: Mower WR, Hoffman JR, Pollack CV, Zucker MI, Browne BJ, Wolfson AB. NEXUS Group. Use of plain radiography to screen for cervical spine injuries. Ann Emerg Med 2001; 38: Demetriades D, Charalambides K, Chawan S, Hanpeter D, Alo K, Velmahos G, Murray J, Asensio J et al. Nonskeletal cervical spine injuries: epidemiology and diagnostic pitfalls. J Trauma 2000; 48: Aprahamian C, Thompson BM, Finger WA, Darin JC. Experimental cervical spine injury model; evaluation of airway management and splinting techniques. Ann Emerg Med. 1984; 13: Hellivel V, Gabbott DA. The effect of single handed cricoid pressure on cervical spine movement after applying manual inline stabilization. A cadaver study. Resuscitation 2001; 49: Heath KJ. The effect on laryngoscopy of different cervical spine immobilization techniques. Aanesthesia 1994; 49: Walls RM. Airway management in the blunt trauma patient; how important is the cervical spine? Can J Surg 1992; 35: Bivins H, Ford S, Bezmalinovic Z, Price HM, Williams JL. The effect of axial traction during orotracheal intubation of the trauma victim with an unstable cervical spine. Ann Emerg Med 1988; 17: Lennarson PJ. Smith D, Todd MM, Carras D, Sawin PD, Brayt J, Sato Y, Traynelis VC. Segmental cervical spine motion during orotracheal intubation of the intact and injured spine with and without external stabilization. J Neurosurg 2000; 92 (2 Suppl): Sawin PD Todd MM, Traynelis VC, Farrel SB, Nader A, Sato Y, Clausen JD, Goel VK. Cervical spine motion with direct laryngoscopy and orotracheal intubation. An in vivo cinefluoroscopic study of subjects without cervical abnormality. Anesthesiology 1996; 85: Hastings RH, Wood PR. Head extension and laryngeal view during laryngoscopy with cervical spine stabilization maneuvers. Anesthesiology 1994; 80: Nolan JP, Wilson ME. Orotracheal intubation in patients with potential cervical spine injuries. An indication for the gum elastic bougie. Anaesthesia 1993; 48: Hastings RH, Vigil AC, Hanna R, Yang BY, Sartoris DJ. Cervical spine movement during laryngoscopy with Bullard McIntosh and Miller Laryngoscopes. Anesthesiology 1995; 82: Laurent SC, de Melo AE, Alexander-Williams JM. The use of the McCoy laryngoscope in patients with simulated cervical spine injuries. Anaesthesia 1996; 51: Abrams KJ, Desai N, Katsnelson T. Bullard laryngoscope for trauma airway management in suspected cervical spine injuries. Anesth Analg 1992; 74: Weiss M, Hartmann K, Fischer JE, Gerber AC. Use of angulated intubating laryngoscope in children undergoing manual inline neck stabilization. Br J anaesth 2001; 87: Donaldson WF, Towers JS, Doctor A. A methodology to evaluate motion of the unstable spine during intubation techniques. Spine 1993; 18: Donaldson WF, Heil BV, Donaldson VP, Silvaggio VJ. The effect of airway manoeuvres on the unstable C1-C2 segments. A cadaver study. Spine 1997; 22: Benumof JL. Management of the difficult adult airway. With special emphasis on awake tracheal intubation. Anesthesiology 1991; 75: Brimacombe J. Berry A. Laryngeal mask airway insertion. A comparison of the standard versus neutral position in normal patients with a view too its use in cervical spine instability. Anaesthesia 1993; 48: Nakazawa K, Tanaka N, Ishikawa S, Ohmi S, Ueki M, Saitoh Y, Makita K, Amaha K. Using the intubating laryngeal mask airway (LMA-Fastrach) for blind endotracheal intubation in patients undergoing cervical spine operation. Anesth Analg 1999; 89: Wong JK, Tongier WK, Armbruster SC, White PF. Use of the intubating laryngeal mask airway to facilitate awake orotracheal intubation in patients with cervical spine disorders. J Clin Anesth 1999; 11: Keller C, Brimacombe J, Keller K. Pressure exerted against the cervical vertebrae by the standard and intubating laryngeal mask airways: a randomized controlled cross over study in fresh cadavers. Anesth Analg 1999; 89: Kihara S, Watanabe S, Brimacombe J, Tagichi N, Yaguchi Y, Yamasaki Y. Segmental cervical spinal movement with the intubating laryngeal mask during manual inline stabilization in patients with cervical pathology undergoing cervical spine surgery. Anesth Analg 2000; 91; Wakeling HG, Nightingale J. The intubating laryngeal mask airway does not facilitate tracheal intubation in the presence of a neck collar in simulated trauma. Br J Anaesth 2000; 84: Aoyama K, Takenaka I, sata T, Shigematsu A. Cricoid pressure impedes positioning and ventilation through the laryngeal mask airway. Can J Anaesth 1996; 43: Fitzgerald RD, Krafft P, Skrbensky G, Pernerstorfer T, Steiner E, Kapral S, Weinstabl C. Excursions of the cervical spine during tracheal intubation: blind oral intubation compared with direct laryngoscopy. Anaesthesia. 1994; 49: Gerling MC, Davis DP, Hamilton RS, Morris GF, Vilke GM, Garfin SR, Hayden SR. Effect of surgical cricothyrotomy on the unstable cervical spine in a cadaver model of intubation. J Emerg Med 2001; 20: Criswell JC, Parr MJ, Nolan JP. Emergency airway management in patients with cervical spine injuries. Anaesthesia. 1994; 49: Suderman VS, Crosby ET, Lui A. Elective oral tracheal intubation in cervical spine-injured adults. Can J Anaesth. 1991; 38: Crosby ET, Lui A. The adult cervical spine; Implications for airway management. Can J Anaesth 1990; 37: Wood PR, Lawler PGP. Managing the airway in cervical spine injury. A review of the advanced trauma life support protocol. Anaesthesia 1992; 47:

8 UMAMAHESWARA : AIRWAY MANAGEMENT IN NS PATIENTS Peuschel SM, Scola FH. Atlantoaxial instability in individuals with Down s syndrome; epidemiologic, radiographic and clinical studies. Pediatrics 1987; 80: Moore RA, McNicholas KW, Warran SP. Atlantoaxial subluxation with symptomatic spinal cord compression in a child with Down s syndrome. Anesth Analg 1987; 66: Williams JP, Someville GM, Miner ME, Reilly D. Atlantoaxial subluxation and trisomy-21: another perioperative complication. Anesthesiology 1987; 67: White PF. Schlobohm RM, Pitts LH, Lindauer JM. A randomized study of drugs for preventing increasing intracranial pressure during endotracheal suctioning. Anesthesiology 1982; 57: Cole IE, Keene M. Nasal obstruction in pituitary tumours. J Laryngol Otol. 1981; 95: Summers GW. Nasal obstruction caused by a pituitary chromophobe adenoma. Laryngoscope. 1976; 86: Isono S, Saeki N, Tanaka A, Nishino T. Collapsibility of passive pharynx in patients with acromegaly. Am J Respir Crit Care Med. 1999; 160: Seidman PA, Kofke WA, Policare R, Young M. Anaesthetic complications of acromegaly. Br J Anaesth. 2000; 84: Law-Koune JD, Liu N, Szekely B, Fischler M. Using the intubating laryngeal mask airway for ventilation and endotracheal intubation in anaesthetized and unparalyzed acromegalic patients. J Neurosurg Anesthesiol. 2004; 16: Iked K, Watanabe K, Suzuki H, Oshima T, Tanno N, Shimomura A, Sunose H, Takasaka T, Ikeda H, Yoshimoto T. Nasal Airway resistance and olfactory acuity following transsphenoidal pituitary surgery. Am J Rhinol 1999; 13: Paul M, Dueck M, Kampe S, Petzke F. Failure to detect an unusual obstruction in a reinforced endotracheal tube with fiberoptic examination. Anesth Analg 2003; 97: Bhadrinarayan V, Umamaheswara Rao GS. Unilateral facial and neck swelling after infratentorial surgery in the lateral position. Anesth Analg 1999; 89: INDIAN JOURNAL OF ANAESTHESIA (Official Bimonthly Publication of the Indian Society of Anaesthesiologists) ADVERTISEMENT TARIFF - PER INSERTION Position Single Colour Two Colour Three Colour Four Colour Back Cover Rs.18,000 Rs.20,000 Rs.27,000 2 nd & 3 rd Covers Rs.10,000 Rs.15,000 Rs. 18,000 Rs.25,000 Last Page Rs. 9,000 Rs. 14,000 Rs. 17,000 Rs. 23,000 1 st & 2 nd Pages Rs. 9,000 Rs. 14,000 Rs. 17,000 Rs. 23,000 Inside Full Page Rs. 8,000 Rs.12,000 Rs.15,000 Rs.20,000 Inside Half Page Rs. 5,000 Inside Quarter Page Rs. 3,000 INSERT : Rs. 25,000 (Page Numbers will be allotted to Inserts also). DISCOUNTS : For two continuous issues - 5% For six continuous issues 15% PAYMENT : Has to be made in the form of crossed DD favouring Editor, Indian Journal of Anaesthesia, payable at Belgaum, (Karnataka) PRINT DATA : Page size 26 x 19 cm Print Area Full Page: 22 x 15.5 cm Half Page: 11 x 15.5 cm MATERIALS : Colour: Colour separated positives along with artworks and proofs B and W : Artpulls and artworks. CIRCULATION : 12,000 Please Contact: Dr. P.F.Kotur, Editor, IJA.