The laryngeal mask airway: clinical appraisal in 250 patients

The laryngeal mask airway consists of a tubular oropharyngeal airway to the distal end of which is sealed a silicone laryngeal mask with an inflatable rim which provides an airtight seal around the larynx. It provided a clear airway in 238 of 250 elective and emergency non-obstetrical patients for a wide variety of surgical procedures, ranging from minor gynaecological and urological procedures to major abdominal and orthopaedic surgery with either spontaneous respiration or intermittent positive pressure ventilation. Anaesthetic techniques and drugs were similar to those which would have been used for the same procedures if face-mask or tracheal intubation had been employed. Blind insertion of the laryngeal mask airway was successful at the first attempt in 187 patients, some manipulation was required in 61 patients, and insertion was impossible in two patients, each of whom had a small mouth. In ten patients tracheal intubation was required because of airway obstruction or a large gas leak. The LM airway does not require laryngoscopy for its insertion, it relieves the anaesthetist's hands from holding a face-mask, it cannot be misplaced in the oesophagus, and it is well tolerated during emergence from anaesthesia.     

Laryngeal mask airway with mouth opening less than 20 mm

We describe the use of a laryngeal mask airway in three adult patients whose mouth opening varied from 12 mm to 18 mm. The first patient’s incisai opening was 12 mm. His airway was otherwise normal and the standard laryngeal mask was used as the definitive airway for the 90 min revision of facial scars and bone graft to mandible. The second patient, who had an incisai opening of 18 mm, was scheduled for posterior fossa craniotomy. She adamantly refused awake fibreoptic tracheal intubation. Following induction of general anaesthesia, a standard laryngeal mask was inserted and, through this, fibreoptic intubation was performed. The third patient, in addition to a mouth opening of only 18 mm, had limited neck movement from previous flap reconstruction following mandibulectomy, hemiglossectomy and radical neck dissection. For three more reconstructive head and neck procedures that ranged from 90 min to nine hours, the flexible reinforced laryngeal mask was inserted under topical anaesthesia and its correct position confirmed by fibreoptic laryngoscopy before induction of general anaesthesia. Maintenance of anaesthesia in all cases was uneventful and there were no postoperative complications. Cette observation décrit l’utilisation du masque laryngé chez trois adultes avec une ouverture buccale dont les limites se situaient entre 12 et 18 mm. Le premier patient avait une ouverture interincisive de 12 mm. Ses voies respiratoires étaient par ailleurs normales et un masque laryngé standard a été utilisé pour le maintien de la perméabilité des voies aériennes pendantune intervention de 90 min effectuée pour retoucher des cicatrices faciales et effectuer une greffe osseuse à la machoire. La seconde patiente dont l’ouverture interincisive était limitée à 18 mm était programmée pour une craniotomie de la fosse postérieure. Elle refusait intensément l’intubation vigile par fibroscope. Après l’induction de l’anesthésie générale, l’intubation fibroscopique a été réalisée a travers un masque laryngé standard déjà inséré. Le troisième patient avait, en plus d’une restriction de l’ouverture interincisive à 18 mm, une limitation des mouvements cervicaux causés par une intervention de reconstruction avec lambeau cutané après une mandibulectomie, une hémi glossectomie et une dissection radicale du cou. Pour trois autres chirurgies de reconstruction cervicale et céphalique ultérieures, un masque laryngé renforcé a été inséré sous anesthésie topique et sa position vérifiée sous laryngoscopie fibroscopique avant l’induction de l’anesthésie. Dans tous les cas, l’anesthésie s’est déroulée sans incidents et sans complications postopératoires.

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An erratum to this article is available at .     

Pressure support ventilation with the laryngeal mask airway: a method to manage severe reactive airway disease postoperatively

The use of a laryngeal mask airway (LMA) and a bi-level positive airway pressure (BiPAP®) machine is described in a postoperative thoracotomy patient with reactive airway disease. The LMA was placed to avoid reintubation of the trachea after a double lumen tube was no longer necessary. Placement in an awakening patient and positive-pressure ventilatory support were well tolerated and did not trigger a bronchospastic response. The patient was able to cough and breathe deeply with the LMA while receiving ventilatory assistance in the postanaesthesia care unit (PACU). The LMA is a therapeutic option to tracheal reintubation in patients who need postoperative ventilatory support after one-lung anaesthesia.     

Elective oral tracheal intubation in cervical spine-injured adults

There is controversy regarding the optimal mode of elective tracheal intubation in the patient with an unstable cervical spine following trauma. A ten-year review of 150 patients with traumatic cervical spine injuries with well-preserved neurological function, presenting for operative stabilization, was conducted to compare neurological outcome with the mode of tracheal intubation. Preoperative neurological deficits were identified in 49 patients (33%); most were single-level radiculopathies. Intubation occurred after induction of general anaesthesia in 83 patients (55%) and in 67 patients (45%) the tracheas were intubated with the patient awake. One hundred and six patients (71%) underwent oral tracheal intubation and 44 underwent nasal tracheal intubation. Ten intubations were deemed to be difficult requiring more than one attempt to effect intubation. Cervical spine immobilization during intubation was documented in 86 patients (57%). Weighted traction or manual in-line traction were the two manoeuvres most commonly employed to maintain spinal alignment during intubation. After surgery, two patients had new neurological deficits. There were no differences in neurological outcome whether intubation was performed while the patient was awake or under general anaesthesia, or comparing oral tracheal intubation with all other techniques (P = 0.5, Fisher exact test). Also, in-line traction did not affect neurological outcome. Oral tracheal intubation with in-line stabilization, either performed after induction of general anaesthesia or with the patient awake, remains an excellent option for elective airway management in patients with cervical spine injuries.     

Evaluation of the Augustine Guide™ for difficult tracheal intubation

Successful tracheal intubation with Augustine Guide ? (Augustine Medical, Inc., Eden Prairie, MN) in patients with normal airways has recently been described. There are no studies describing Augustine Guide (AG) use in patients with difficult airways. Accordingly, we studied AG intubation in a population of patients with expected difficult airways due to cervical spine pathology, limited mouth opening, obesity, facial trauma or deformity due to previous operation or radiation and in patients with unexpectedly difficult airways. A total of 44 patients were studied. The AG was used as a primary intubating tool in patients with known difficult airways (n = 36) and as a secondary intubating tool in patients with unexpected inability to intubate using conventional direct laryngoscopy (n = 8). Airway difficulty was predicted by history and physical examination. Intubations were performed under general anaesthesia in 40 of the 44 patients studied. In four patients with predictably difficult airways, topical anaesthesia and sedation were used. Backup methods to achieve intubation were available. Thirty-two of the 36 with known or suspected difficult airways were classified as Mallampati Class III or IV. In the remaining eight patients the preoperative examination suggested an easy airway; however, after induction of general anaesthesia, their laryngeal inlet could not be seen using direct laryngoscopy. Using the AG, all were intubated successfully (36/44 at the first attempt, in 8/44 repositioning of the AG to allow successful laryngeal entry of the stylet was necessary). There were no failures or complications secondary to AG use. This study shows that the AG is a useful device for oral tracheal intubation in patients with known or unexpectedly difficult airways.     

Difficult intubation in the parturient

Difficult or failed tracheal intubation is an important cause of anaesthetic-related maternal morbidity and mortality. The incidence of failed intubation in parturients is estimated to be as frequent as 1 in 500; that of mortality is unknown, although some 10-13 pregnant women in England, Scotland and Wales die each year because of anaesthetic-related complications. To prevent such catastrophes, all necessary monitors and equipment should be available, including that needed to deal with a failed intubation. Assessment of the patient may lead to preoperative recognition of a difficult airway; altered positioning may be of help both in recognition and management. Furthermore, adequate assistance, correct use of cricoid pressure, and confirmation of tracheal intubation are fundamental to safe practice. Lastly, should the anaesthetist fail to intubate the patient's trachea, a management protocol is suggested.     

Awake intubation of the adult trachea using the Bullard laryngo-scope

Awake intubation using the Bullard laryngoscope can be comfortably and easily performed in the adult. Five cases are presented in which tracheal intubation was performed under topical anaesthesia with light intravenous sedation. In each case, topical anaesthesia was performed by insertion of a Guedel oral airway, with lidocaine ointment applied to the inferior and posterior surfaces. In one case, Bullard intubation was successful where direct laryngoscopy and multiple attempts at bronchoscopic intubation by three different operators had failed. We conclude that the Bullard laryngoscope can be easily used in awake patients and may be a useful alternative where other methods for awake intubation have failed.     

Randomized comparison of outcome after propofol-nitrous oxide or enflurane-nitrous oxide anaesthesia in operations of long duration

A randomized, prospective, comparative study was performed to evaluate induction characteristics, haemodynamic changes and recovery in 60 ASA I-II patients undergoing mainly gynaecological laparotomies with either propofol or thiopentone-enflurane anaesthesia. The propofol group (n = 30) received 2 mg.kg-1 propofol for induction of anaesthesia followed by propofol infusion. The thiopentone-enflurane group (n = 30) received thiopentone 4 mg.kg-1 for induction followed by enflurane (0.5-2 per cent). All patients received nitrous oxide (66 per cent] in oxygen begun one minute after tracheal intubation, and fentanyl (1.5 micrograms.kg-1) four minutes prior to induction. Other drugs administered during or after anaesthesia were similar among the groups. Haemodynamic measurements were similar between propofol and enflurane groups except after tracheal intubation when the mean arterial pressure was lower in the propofol group (P less than 0.05). The propofol group had significantly less (P less than 0.01) emesis in the recovery room than the enflurane group. The propofol group experienced significantly less (P less than 0.05) dizziness, depression/sadness and hunger than the enflurane group in the postoperative period as assessed with a visual analogue questionnaire. We conclude that propofol provided better outcome than enflurane in terms of these nonvital but annoying outcome measures after relatively long intra-abdominal operations.     

Comparison of a rigid laryngoscope with the ultrathin fibreoptic laryngoscope for tracheal intubation in infants

The flexible ultrathin fibreoptic laryngoscope allows placement of endotracheal tubes as small as 2.5 mm internal diameter. The purpose of this study was to document the safety and efficacy of intubation using an ultrathin fibreoptic laryngoscope. Proved safety and efficacy would justify the routine use of fibreoptic laryngoscopy in normal infants to maintain skills needed for management of the difficult infant airway. In this prospective study, 40 infants <24 mo of age scheduled for elective surgery were randomly divided into two equal groups. After inhalation induction of anaesthesia, in 20 infants the trachea was intubated using direct rigid laryngoscopy, and in 20 using the ultrathin fibreoptic laryngoscope (size 1.8 mm OD) Olympus LFP. Time to successful intubation was recorded, as well as blood pressure, heart rate, end-tidal CO₂ and oxygen saturation. Airway trauma in the operating room, the post-anaesthesia care unit, and on the first postoperative day was recorded. The intubation times using rigid laryngoscopy were less than those using fibreoptic laryngoscopy (13.6 ± 0.9 sec (mean ± SEM) vs 22.8 ± 1.7 sec; P < 0.01). Oxygen saturation and end-tidal CO₂ readings were not different between the two groups. After intubation, blood pressure and heart rate increased equally in both groups, returning to normal within one to two minutes. There was no difference in the airway trauma between groups. We conclude that the ultrathin fibreoptic laryngoscope is a safe and effective method for tracheal intubation in infants and may be used routinely in order to maintain fibreoptic airway skills.     

Amygdalectomies et masque laryngé renforcé

One hundred children were randomly allocated to receive general anaesthesia for tonsillectomy either through a preformed tracheal tube or a reinforced laryngeal mask. The insertion of both devices was easy but occasionally, with the laryngeal mask, the airway became obstructed during the Boyle-Davis gag insertion. There was more coughing after intubation (ET 26%, RLM 0% P < 0,001) and extubation (ET 34% RLM 0%, P < 0,001), than after insertion and withdrawal of the RLM. Oxygen desaturation (ET 14%, RLM 2%, P < 0,02) and internal contamination with blood seepage (ET 30%, RLM 4% P < 0,001) occurred less frequently with the RLM. Deux séries de 50 enfants devant subir une amygdalectomie et dont la liberté des voies aériennes a été assurée après tirage au sort par une sonde endotrachéale préformée (SE) ou un masque laryngé renforcé (MLR), ont été comparées. L’insertion des deux dispositifs se fait avec la même facilité mais l’introduction de l’ouvre-bouche peut mobiliser le masque et nécessiter sa reposition. L’intubation (SE 26% ML 0%, P < 0,001) et l’extubation (SE 34% ML 0%, P < 0,001) provoquent des secousses de toux que le masque ne déclenche pas. La désaturation postopératoire (SE 14% ML 2%, P < 0,02) et la contamination des voies aériennes (SE 30%, ML 4% P < 0,001) sont plus rares avec le masque laryngé.     

Acute epiglottitis in the adult: is intubation mandatory?

Acute epiglottitis (AE) in the adult results in inflammation of the supraglottic structures and carries the potential for complete airway obstruction. There is disagreement in the medical literature as to the appropriate management of the airway in the adult with AE. Some authors advocate intubation in all patients while others propose more selective intervention, intubating the trachea only in those patients presenting with airway compromise. We reviewed our institutional experience with 21 patients over the last seven years admitted with a proven diagnosis of AE. Six patients presented with respiratory distress, three in severe distress with symptoms and signs of upper airway obstruction. The three patients in severe distress were taken to the operating room, in two the tracheas were intubated and one underwent tracheostomy after failed intubation. All other patients were monitored but their tracheas were not intubated. The majority of the patients were monitored for 24 hr in the ICU before transfer to wards. No patient initially monitored required tracheal intubation for progression of disease. There were no deaths. Recommendations for the care of the airway in the adult with AE based on our experience and a review of approximately 1000 cases reported in the last ten years are presented. It is our opinion that adults presenting without respiratory symptoms may be safely monitored in an intensive care setting given that provision is made for tracheal intubation or tracheostomy should respiratory distress become evident.     

Functional stridor diagnosed by the anaesthetist

While stridor is an ominous sign implying severe airway stenosis, not all stridor has an organic aetiology. We present two cases of functional stridor in which the diagnosis was made by the anaesthetist. As experts in the management of difficult airways, anaesthetists should be aware of this clinical entity. Recurrent episodes present as aphonia, dysphonia, dyspnoea, apnoea or unconsciousness. Stridor is usually inspiratory. Flow volume loops show a pattern of variable extrathoracic obstruction with diminished peak inspiratory flow. Awake fibreoptic laryngobronchoscopy reveals normal airway anatomy, intense adduction of false and true vocal cords during inspiration and normal vocal cord motion on expiration. Treatment of functional stridor is supportive. The diagnosis of functional stridor demands exclusion of life-threatening airway stenosis of organic aetiology. A high index of suspicion for this clinical entity will reduce the incidence of unnecessary interventions such as tracheal intubation and tracheostomy.     

Attenuation of the catecholamine response to tracheal intubation with oral clonidine in children

We conducted a prospective, randomized, double-blind, controlled clinical trial to examine (1) whether plasma catecholamine (CA) concentrations increased in response to tracheal intubation in children, and (2) the effects of clonidine on the CA responses. Sixty children (ASA physical status I) aged 7– 13 yr were allocated to one of three groups (n = 20 for each group): diazepam 0.4 mg · kg^{? 1} (active control), clonidine 2 μg · kg^{? 1}, or clonidine 4 μg · kg^{? 1} po. These agents were administered 105 min before induction of anaesthesia followed by oral atropine 0.03 mg · kg^{? 1} given 60 min before anaesthesia which was induced with thiamylal 5 mg · kg^{? 1} and tracheal intubation was facilitated with vecuronium 0.2 mg · kg^{? 1}. Laryngoscopy, lasting 30 sec, was attempted two minutes after administration of the induction agents. Serial values for blood pressure, heart rate, and venous plasma CA concentrations were compared among the three groups and with the respective preinduction measurements. Children receiving diazepam or clonidine 2 μg · kg^{? 1} showed remarkable increases in systolic and diastolic blood pressures, heart rate, and plasma CA concentrations in response to tracheal intubation (P < 0.05). The increases were similar for the two regimens. These haemodynamic and CA changes were smaller in children receiving clonidine 4 μg · kg^{? 1} (P < 0.05). The haemodynamic responses were positively correlated with the CA responses. These findings indicate that tracheal intubation following rapid sequence induction of anaesthesia in children provokes a reflex increase in sympathetic activity characterized by increased plasma CA concentrations, and that attenuation of the cardiovascular changes with a high oral dose of clonidine may be due to suppression of the increase in sympathetic activity evoked by the intubation.     

Oral clonidine premedication attenuates the haemodynamic effects associated with ketamine anaesthetic induction in humans

Induction of anaesthesia is often associated with undesirable variations in blood pressure and heart rate. Clonidine has been demonstrated to attenuate many of these undesirable effects when used as a premedicant. Other alpha₂ adrenergic agonists have been used to ameliorate the cardiostimulatory effects of ketamine in animals but there are few data on the use of this combination in humans. The effect of oral clonidine premedication, 5 μg · kg^?1 on the haemodynamic changes induced by iv ketamine was studied in 42 patient volunteers. Ninety minutes before surgery, patients randomly received clonidine (C), diazepam (D), or a placebo (P) in a double-blinded fashion. Anaesthesia was induced with a ketamine infusion of I mg · kg^?1· min^?1 until loss of consciousness. Heart rate and phasic blood pressure were measured noninvasively prior to induction, before and up to seven minutes after tracheal intubation. There were no differences in demographics or baseline vital signs among the three groups. With ketamine administration, increases in heart rate and blood pressure were less in those patients given C preoperatively than in those who received either D or P. The peak increase in mean blood pressure was 39% (C) versus 70% (D) and 55% (P) (P < 0.01). Heart rate increased by a maximum of 20% (C) versus 41% (D) and 46% (P) (P < 0.01). We conclude that oral clonidine attenuates the hyperdynamic effects of anaesthetic induction with iv ketamine.     

Fibreoptic intubation

Although not widely utilized, fibreoptic techniques represent a dramatic advance in the management of the difficult intubation. Particularly suited to the awake patient in the elective setting, fibreoptic intubation can abo be useful in selected emergency situations, and can be done under general anaesthesia. In the awake patient fibreoptic intubation maintains a wide margin of safety while producing minimal patient discomfort, but requires adequate local anaesthesia of the airway. Intimate familiarity with the bronchoscope and the anatomy of the upper airway is essential as is careful attention to various aspects of technique. Intubation mannequins can be readily utilized to develop dexterity in bronchoscopic manipulation and intubation workshops are also effective in improving skills. This CME article provides the clinician with a detailed approach to the technique of fibreoptic intubation based on the author’s personal experience supplemented by a limited literature review. Fibreoptic intubation is not a difficult skill to master and should be in the armamentarium of all practising anaesthetists.     

A comparison of fentanyl,esmolol, and their combination for blunting the haemodynamic responses during rapid-sequence induction

The purpose of this randomized, double-blind study was to compare the ability of a combination of fentanyl and esmolol to blunt the haemodynamic effects of intubation with that of either agent alone. Patients received fentanyl or saline four minutes before, and esmolol or saline two minutes before rapid-sequence induction of anaesthesia. The F2 group (n = 24) received fentanyl 2 micrograms.kg-1, the E2 group (n = 24) received esmolol 2 mg.kg-1, the F2/E2 group (n = 25) received a combination of fentanyl 2 micrograms.kg-1 and esmolol 2 mg.kg-1, and the F5 group (n = 26) received fentanyl 5 micrograms.kg-1. Following tracheal intubation, the maximum percent change from baseline heart rate was less in the F2/E2 and F5 groups (12% and 16% respectively) than in the E2 group (34%)(P < 0.05). The maximum percent changes from baseline systolic blood pressure in the F2/E2 and F5 groups (15% and 6% respectively) were less than in the F2 and E2 groups (24% and 33% respectively) (P < 0.05). The combination of a low dose of fentanyl and esmolol provides an alternative to a higher dose of fentanyl for blunting the haemodynamic responses to laryngoscopy and tracheal intubation during rapid-sequence induction in healthy patients.     

Tracheal intubation through the intubating laryngeal mask in patients with unstable necks

BACKGROUND: In patients with unstable necks, the neck should be stabilized during induction of anaesthesia, but this may make tracheal intubation difficult. Awake intubation may produce straining, which could be detrimental to the unstable neck. METHODS: We studied 20 patients with unstable necks to examine the efficacy of insertion of the intubating laryngeal mask under conscious sedation (to minimize the possibility of losing a patent airway and to facilitate fibrescope-aided intubation) followed by tracheal intubation through the laryngeal mask after induction of anaesthesia (to reduce stress response to intubation). After the patient had been sedated with midazolam (up to 5 mg) and fentanyl (up to 100 microg), the intubating laryngeal mask was inserted. General anaesthesia was then induced with sevoflurane and tracheal intubation attempted. RESULTS: In all patients, tracheal intubation through the laryngeal mask succeeded without airway obstruction. Neither insertion of the mask under conscious sedation nor tracheal intubation after induction of anaesthesia caused straining, and only two patients moved upper extremities at intubation. Insertion of the laryngeal mask did not significantly alter blood pressure or heart rate. Tracheal intubation significantly increased blood pressure and heart rate, but the increase was considered to be small. CONCLUSIONS: In the patient with an unstable neck with a low risk of pulmonary aspiration, insertion of the intubating laryngeal mask while the patient is sedated may minimize difficulty in obtaining a patent airway before tracheal intubation and may facilitate a fibrescope-aided tracheal intubation; subsequent induction of anaesthesia before tracheal intubation may minimize stress response to intubation.     

Bolus doses of esmolol for the prevention of perioperative hyper-tension and tachycardia

The effectiveness of esmolol, an ultra short-acting cardioselective beta blocker, in the prevention and treatment of post-intubation haemodynamic perturbations, was investigated. Forty-eight ASA physical status I and II patients undergoing hysterectomy were randomly assigned to receive a single intravenous bolus of placebo, esmolol 100 mg, or esmolol 200 mg in a double-blind fashion. This was administered over 15 sec, and immediately followed by thiopentone 3-5 mg.kg-1, succinylcholine 1.5 mg.kg-1, and tracheal intubation 90 sec later. The heart rate following induction of anaesthesia was lower in the esmolol 200 mg group (P less than 0.01); following intubation, the increase in heart rate in the placebo group was greater than in the esmolol groups (P less than 0.05). The systolic blood pressure post-induction was lower in the esmolol 200 mg group (P less than 0.05); following intubation, however, no significant differences were seen among groups in systolic, diastolic, or mean blood pressures. Following tracheal intubation, the incidence of ventricular arrhythmias was lower in the esmolol groups (P less than 0.05). In summary, esmolol in 100 mg and 200 mg doses was effective in mitigating the haemodynamic response following tracheal intubation.     

Mask lung ventilation by ambulance personnel: a performance assessment

We evaluated the ability of basic life support ambulance officers and anaesthetists to perform lung ventilation with a face mask. After induction of anaesthesia and institution of standardized airway conditions the ambulance officer or anaesthetist placed a mask on the patient’s face and lung ventilation was commenced. The order of hand grip (one vs two hands) was randomized. The mask was connected to a ventilator which had flow and pressure transducers in the inspiratory and expiratory breathing circuits. The output of these devices was sent to an electronic integrator to determine volumes. Calibration of the flow transducers was made against a spirometer while ventilating a test lung. Oesophageal insufflation was determined by listening over the epigastrium with a stethoscope. Data collected included presence of gastro-oesophageal insufflation, inspiratory and expiratory volumes. Expiratory volumes for ambulance officers and anaesthetists at 30 cm H₂O were greater than that of ambulance officers at 20 cm H₂O (P < 0.001) but profession of the mask holder or hand grip had no effect on expiratory volume. There was no difference in the mask leak when the professions were compared but ambulance officers had a lower mask leak with a two-handed grip at 20 cm H₂O (P < 0.001). Anaesthetists had a greater incidence of gastro-oesophageal insufflation when a two-handed mask grip was utilized (P < 0.05). In healthy relaxed patients there appeared to be little difference between the ambulance officers and qualified anaesthetists in airway maintenance or mask-holding ability.     

Ankylosing spondylitis: lateral approach to spinal anaesthesia for lower limb surgery

We describe three patients with long-standing ankyolsing spondylitis (AS) who underwent lower limb joint surgery under spinal anaesthesia. At preoperative assessment, it was considered that intubation of the trachea was likely to be difficult or impossible and previous general anaesthesia was associated with increased morbidity. Midline approach spinal anaesthesia failed but the lateral approach was successful. Spinal anaesthesia was induced using a 24 gauge Sprotte (Pajunk) needle with 3.5 ml heavy bupivacaine 0.5% at the L_3–4 interspace with the patients in the sitting position. This resulted in adequate sensory blockade for the surgical procedure. None of the patients required airway interventions but equipment and aids to secure airway were available.