Removal of the laryngeal mask airway: factors affecting the incidence of post-operative adverse respiratory events in 300 patients

The purpose of this study is to compare the incidence of undesirable respiratory events when the laryngeal mask airway is either removed from patients who are fully awake or from patients who are deeply anaesthetized. Three-hundred patients aged 1.5-81 years were randomly assigned to have their laryngeal mask airway removed either when deeply anaesthetized or after airway reflexes had returned. The occurrence of adverse respiratory events (coughing, oxygen desaturation and airway obstruction) was recorded. Airway obstruction after laryngeal mask airway removal was evident in 20% of patients in the deep anaesthesia group and in 8% of patients in the awake group (P = 0.007). In spite of this finding, oxygen desaturation in children of less than 6 years of age (SaO2 < 96%) occurred most frequently after awake removal (31.3%) compared with deep anaesthesia removal (4.5%) (P = 0.023).     

Airway complications in infants: comparison of laryngeal mask airway and the facemask-oral airway

PURPOSE: To compare the incidence of airway complications in children less than one year of age whose airways were maintained during anesthesia with either a laryngeal mask airway (LMA) or a facemask and oral airway (FM-OA). METHODS: We randomized 49 - ASA class 1&2 - infants to an LMA or FM-OA group. All infants were undergoing minor general, urological or orthopedic procedures. Anesthesia was induced and maintained with halothane in nitrous oxide 50% and oxygen. The airway was removed in both groups when the infant was awake. The occurrence of airway complications (breath-holding, coughing, laryngospasm, secretions, obstruction and oxygen saturation < 95%) at induction of anesthesia, intraoperatively and during emergence from anesthesia was recorded. RESULTS: Airway complications occurred perioperaively in 15 of 27 infants in the LMA group and in 5 of 22 infants in the FM-OA group (P: 0.02). CONCLUSION: In infants, the use of the LMA is associated with an increased incidence of airway complications compared with the use of the FM-OA.     

喉罩全麻白内障患儿手术苏醒期拔管时机的探讨

目的 降低惠儿全麻苏醒期喉罩拔出后呼吸道并发症的发生率,为患儿喉罩拔管时机的选择提供临床依据.方法 采用计算机随机将择期喉罩全麻下行白内障手术的患儿60例分为镇静状态喉罩拔管组(镇静组,33例)和清醒状态喉罩拔管组(清醒组,27例).在麻醉后恢复室观察并记录两组患儿拔出喉罩后呼吸道并发症发生率.结果 手术苏醒期,镇静组无一例发生呛咳,清醒组13例出现呛咳,两组比较,差异有统计学意义(P＜0.01).结论 患儿镇静状态下拔出喉罩能降低拔管后呛咳发生率,以保证患儿安全渡过全麻苏醒期.     

Is adenoidectomy in children safer with laryngeal mask airway or with tracheal intubation?

Adenoidectomy in paediatric outpatient surgery is assumed to require tracheal intubation (TT). The laryngeal mask airway (LMA) commonly used for general paediatric surgery has never been previously studied for adenoidectomy. We therefore prospectively compared in a randomized manner, the incidence of complications with TT and LMA in 56 children undergoing adenoidectomy. Preoperative, intraoperative and the lowest SPO₂ values after removal of either TT or LMA were recorded. The respiratory complications, cough, stridor and/or laryngospasm, were recorded intraoperatively and after removal of the airway device. The oxygen saturation levels were significantly higher in the laryngeal mask airway group both intraoperatively and after removal of the respiratory device (P<0.05). The incidence of respiratory complications was lower in the LMA group. In conclusion we have shown that the laryngeal mask airway with a flexometallic tube is a satisfactory alternative to tracheal intubation for outpatient paediatric adenoidectomy.     

Laryngeal mask airway placement in paediatric patients: a comparison of two general anaesthetic techniques

Guidelines for paediatric practice suggest that the laryngeal mask airway (LMA) is best inserted after a period of inhalational anaesthesia. This study compared the success rate and incidence of complications for LMA placement using two different techniques of general anaesthesia. Sixty ASA I or II patients between the ages of 19 months and 14 years of age were studied. In Group 1, anaesthesia was induced with propofol, 4 mg·kg⁻¹, and placement of the LMA was then attempted. In Group 2, anaesthesia was similarly induced with propofol, but the lungs were then ventilated with halothane in oxygen for placement of the LMA. Although limb movement occurred more often in Group 1 ( P < 0.001), there were no differences between the groups for other complications, nor for success in placing the LMA. We conclude that in paediatric patients, the LMA may be successfully placed using propofol, 4 mg·kg⁻¹ alone.     

An evaluation of the laryngeal mask airway during routine paediatric anaesthesia

During a six week period, all anaesthetists at the Royal Hospital for Sick Children, Glasgow were asked to complete a questionnaire whenever a laryngeal mask airway (LMA) was used. Seniority of anaesthetist, age of patient, anaesthetic technique, technique of LMA insertion, ease of LMA insertion, and any problems encountered either during LMA insertion, or during induction, maintenance, and recovery from anaesthesia were documented. Complete data were obtained from 211 patients aged 5 weeks to 15 years. Ninety-six children were anaesthetized by consultant paediatric anaesthetists, and 115 by trainees. LMA insertion was successful at the first attempt in 86% of all cases, achieved with some difficulty in 11% of cases, and failed or its use was abandoned in 6 cases (3%). Difficulties other than with LMA placement per se occurred in 11% of cases during induction of anaesthesia. Seniority of anaesthetist and choice of anaesthetic agent influenced neither the success rate of insertion nor the frequency of other difficulties encountered during induction of anaesthesia. Significantly fewer problems were encountered at LMA removal if this was done during deep anaesthesia compared with removal when protective reflexes were present (P < 0.05).     

Removal of the laryngeal mask airway in children: anaesthetized compared with awake

We studied 60 children, aged 12 months to 8 yr, undergoing plastic surgery under general anaesthesia supplemented by regional anaesthesia. Patients were allocated randomly to have the laryngeal mask airway removed either on awakening or while anaesthetized. Subsequent observation of respiratory factors and oxygen saturation showed a significant difference between the groups for coughing (P < 0.001), with a greater incidence (17 of 33) in the awake group compared with those from whom the laryngeal mask airway was removed while anaesthetized (two of 27). There were no differences in the incidences of laryngospasm, desaturation (< 95%) and excess salivation between the groups. Removed of the laryngeal mask airway during deep anaesthesia reduced coughing in the immediate postoperative period.      

Airway management in spontaneously breathing anaesthetized children: comparison of the Laryngeal Mask Airway with the cuffed oropharyngeal airway

BACKGROUND: The efficacy and safety of the smallest size of the cuffed oropharyngeal airway (COPA) for school age, spontaneously breathing children was investigated and compared with the Laryngeal Mask Airway (LMA). METHODS: Seventy children of school age (7-16 years) were divided into two groups: the COPA (n=35) and the LMA (n=35). Induction was with propofol i.v. or halothane, nitrous oxide, oxygen and fentanyl. After depression of laryngopharyngeal reflexes, a COPA size 8 cm or an LMA was inserted. Ventilation was manually assisted until spontaneous breathing was established. For maintenance, propofol i.v. and fentanyl or halothane with nitrous oxide were used. Local anaesthesia or peripheral blocks were also used. RESULTS: Both extratracheal airways had a highly successful insertion rate, but more positional manoeuvres to achieve a satisfactory airway were required with the COPA, 28.6% versus LMA 2.9%. The need to change the method of airway management was higher (8.6%) in the COPA group. After induction, the need for assisted ventilation was higher in the LMA group 54.3% versus 20% in the COPA group. Airway reaction to cuff inflation was higher in the LMA group 14.3% versus COPA 5.7%. Problems during surgery were similar, except continuous chin support to establish an effective airway was more frequent (11.4%) in the COPA group. In the postoperative period, blood on the device and incidence of sore throat were detected less in the COPA group. CONCLUSIONS: The COPA is a good extratracheal airway that provides new possibilities for airway management in school age children with an adequate and well sealed airway, during spontaneous breathing or during short-term assisted manual ventilation.     

Continuous monitoring of oesophageal pH during general anaesthesia with laryngeal mask airway in children

We studied the incidence of gastro-oesophageal reflux (GOR) during general anaesthesia with the laryngeal mask airway (LMA) in a paediatric population with two ventilatory regimes: spontaneous breathing and controlled mechanical ventilation (CMV). Thirty children between 6 months and 15 years, ASA I-II, for routine surgery, were randomly assigned in two groups: spontaneous ventilation (n=14), and CMV (n=16). A pH probe was situated in the central third of the oesophagus. Some 66% of the patients breathing spontaneously had GOR episodes vs. 92% of the patients with CMV (P < 0,01). Reflux took place mainly after LMA removal (21% vs. 68%; P < 0,01) and in the Postanaesthetic Care Unit (PACU) (29% vs. 43%; P < 0,05). There was a high incidence of GOR during general anaesthesia and in the PACU in paediatric patients anaesthetized with the LMA. GOR episodes were significantly more evident in the CMV group, mainly after LMA removal, but without clinical significance.     

Severity of airway hyperreactivity associated with laryngeal mask airway removal: correlation with volatile anesthetic choice and depth of anesthesia.

STUDY OBJECTIVE: To compare the influence of anesthetic depth and choice of volatile anesthetic drug on the incidence and severity of airway hyperreactivity associated with Laryngeal Mask Airway (LMA) removal. DESIGN: Randomized observer-blinded study. SETTING: Ambulatory Surgical Center at a University Medical Center. PATIENTS: 123 ASA physical status I and II children undergoing infraumbilical procedures. INTERVENTIONS: Patients were randomly assigned to one of four treatment groups: Group 1 = anesthetic induction with halothane, maintenance with isoflurane, nitrous oxide (N(2)O), and oxygen (O(2)), LMA removed when child awakened; Group 2 =anesthetic induction and maintenance as in Group 1, LMA removed while child anesthetized with age adjusted 2 minimum alveolar concentration (MAC) end-tidal concentration of isoflurane; Group 3 = anesthetic induction and maintenance with sevoflurane, N(2)O, and O(2), LMA removed when child awakened; Group 4 = anesthetic induction and maintenance as in Group 3, but LMA removed while child anesthetized with age-adjusted 2 MAC end-tidal concentration of sevoflurane. MEASUREMENTS AND MAIN RESULTS: Severity of airway hyperreactivity was graded as mild, moderate, or severe. A significant difference was not found amongst the four groups with respect to mild and moderate airway hyperreactivity. Severe airway hyperreactivity leading to a critical event [partial or complete laryngospasm with oxygen saturation (SPO(2)) < 85%] was only encountered in Group 1 patients (incidence 13%). Adverse airway events (SPO(2) < 90%, vomiting and bronchospasm) were also significantly higher in Group 1 (p < 0.05). Isoflurane use was independently associated with significantly higher airway hyperreactivity when compared with sevoflurane (p < 0.05). CONCLUSIONS: Depth of anesthesia during LMA removal does not appear to affect the incidence or severity of airway hyperreactivity when sevoflurane is the maintenance anesthetic. However, awake LMA removal during isoflurane anesthesia results in a higher incidence of adverse airway events and carries the risk of severe airway hyperreactivity.     

Use of the laryngeal mask airway during ophthalmic surgery results in stable circulation and few complications: a prospective audit

Background: This study was performed to investigate airway complications related to Laryngeal Mask Airway (LMA) use in a selected group of paediatric patients undergoing ophthalmic surgery.
Methods: Ninety-four paediatric patients were enrolled. LMA was inserted under deep general anaesthesia with the standard technique previously described by Brain. Complications during induction, insertion of the LMA, maintenance of anaesthesia, removal of the LMA, emergence and on the first postoperative day were recorded. Failure of insertion, desaturation, laryngospasm, bronchospasm, vomiting, bucking, dislocation of the LMA, breath-holding, and coughing were noted.
Results: There was no significant age-related difference in successful insertion ratio of the LMA. In two patients (2%), the LMA could not be inserted with three attempts and tracheal intubation was performed. Laryngospasm was recorded in three patients (3%), leading to desaturation in two patients (SaO₂95%) during insertion of the LMA. During maintenance of anaesthesia bucking occurred in one patient (1%). After removal of the LMA, incidence of early desaturation following upper airway suctioning was higher in patients with a history of frequent upper respiratory tract infection ( P <0.01). Five patients (5%) had laryngospasm following the LMA removal; breath-holding and coughing were noted in 21 (22%) patients. Circulatory reactions to insertion and removal of the LMA were minimal. The incidence of sore throat on the first postoperative day was only 1%.
Conclusion: LMA can be regarded as a safe product for airway maintenance during ophthalmic surgery with a stable circulation and few complications.     

Complications following use of the laryngeal mask airway in children

Anaesthetic records from 507 children anaesthetized using the laryngeal mask airway (LMA) breathing spontaneously were analysed. Failure to insert the LMA occurred in 10 (2.0%) children and there were difficulties with insertion in 36 (7.1%) children. There was a total of 81 (16%) children with complications in the recovery period. Most of these were not clinically significant. Twenty-three children showed evidence of trauma to the pharynx or larynx. This study demonstrates that the LMA is a safe and effective tool for use in paediatric anaesthesia. However, the incidence of trauma may be higher than expected and attempts should be made to minimize this with a gentle technique and adequate depth of anaesthesia.     

Tracheal extubation in children: halothane versus isoflurane, anesthetized versus awake

The authors compared the incidence of respiratory complications and arterial hemoglobin desaturation during emergence from anesthesia in children whose tracheas were extubated while they were anesthetized or after they were awake and to whom halothane or isoflurane had been administered. One hundred children 1-4 yr of age undergoing minor urologic surgery were studied. After a standard induction technique, patients were randomized to receive either isoflurane or halothane. In 50 patients tracheal extubation was performed while they were breathing 2 MAC of either halothane or isoflurane in 100% oxygen. The remaining 50 patients received 2 MAC (volatile agent plus nitrous oxide) during the operation, but tracheal extubation was delayed until they were awake. A blinded observer recorded the incidence of respiratory complications and continuously measured hemoglobin saturation for 15 min after extubation. When tracheal extubation occurred in deeply anesthetized patients, no differences were found between the two volatile agents. When tracheal extubation of awake patients was performed, the use of isoflurane was associated with more episodes of coughing and airway obstruction than was halothane (P less than 0.05). Awake tracheal extubation following either agent was associated with significantly more episodes of hemoglobin desaturation than was tracheal extubation while anesthetized.     

A comparison of deep vs. awake removal of the laryngeal mask airway in paediatric dental daycase surgery. A randomised controlled trial

Dental anaesthesia provides a potential conflict between anaesthetist and surgeon because of the shared airway. The laryngeal mask airway (LMA) has helped to improve airway control for these procedures, but there is little evidence for best practice on the timing of their removal after airway surgery in the paediatric population. We compared 'awake' and 'deep' removal of the LMA in 196 patients aged from 2 to 15 years in a randomised, controlled study. We found that average peripheral oxygen saturation (SpO2) was lower in the deep group and this was statistically significant (96.2% vs. 94.9%, p = 0.04). It was also found that the deep group had a higher incidence of patients with SpO2 < 95% (p = 0.003) and of patients who coughed (p = 0.003). We conclude that the LMA should be taken out awake in these patients.     

Similar haemodynamic, respiratory and metabolic changes with the use of sevoflurane or halothane in children breathing spontaneously via a laryngeal mask airway

BACKGROUND: In preschool children, short-lasting surgical procedures are often performed under combined inhalational and regional anaesthesia with the child breathing spontaneously via a laryngeal mask airway (LMA). Despite widespread use, only limited data are available on haemodynamic, respiratory and metabolic effects of sevoflurane and halothane during LMA anaesthesia. METHODS: In an open-label, randomised, controlled study, 49 children (aged 3-8 years) were allocated to receive either sevoflurane or halothane in 60% nitrous oxide. After insertion of the LMA, end-tidal concentrations of sevoflurane or halothane were maintained at 1 MAC with the child ventilating spontaneously throughout the entire procedure. Analgesia was provided by caudal block. Haemodynamic and respiratory parameters were recorded, and capillary blood-gas samples were obtained repeatedly. RESULTS: Changes in heart rate (HR) and systolic blood pressure were similar in both groups during all observed periods, apart from a significantly higher increase in HR during inhalational induction with sevoflurane (P<0.05). Regression slope analysis during anaesthesia revealed a decrease of the respiratory rate of 5 breaths h-1 (P<0.001) and an increase of end-tidal PCO2 and capillary PCO2 of about 0.25 kPa h-1 (P<0.001), with no significant difference between the two groups. Base excess, calculated in capillary blood gas samples, did not change over time (P>0.5) in either group. CONCLUSIONS: The use of approximately 1 MAC sevoflurane or halothane in 60% N2O in children breathing spontaneously via LMA resulted in comparable haemodynamic, respiratory and metabolic changes, and clinically relevant deteriorations did not occur during the 65-min study period.     

Timing of removal of the laryngeal mask airway

Previous studies reported that complications associated with removal of the laryngeal mask were more frequent in awake patients than in anaesthetised patients; however, these studies did not comply with the method described in the manufacturer's instruction manual. The reported incidences of regurgitation during the use of the laryngeal mask also differ considerably between studies. We studied these factors in 66 patients in whom the method described in the manual was used. After induction of anaesthesia, the laryngeal mask and a pH probe were inserted and the cuff of the mask was inflated with a minimum volume of air. Anaesthesia was maintained with nitrous oxide and isoflurane in oxygen. At the end of the operation, we randomly allocated patients to one of two groups and the laryngeal mask was removed either while they were still deeply anaesthetised or after they had regained consciousness. No apparent regurgitation occurred in any patient during operation, but one patient in the anaesthetised group regurgitated immediately after removal of the mask. The incidence of complications during or after removal of the laryngeal mask was significantly greater in the anaesthetised group than that in the awake group (p << 0.001; difference [95% CI]: 48.5 [30.5–66.5]%). Therefore, the laryngeal mask can be safely left in place until the patient has regained consciousness after emergence from anaesthesia.     

Emergence airway complications in children: a comparison of tracheal extubation in awake and deeply anesthetized patients

We compared the differences in oxygen saturation and airway-related complications after tracheal extubation in pediatric patients undergoing elective strabismus surgery or adenoidectomy and/or tonsillectomy who were awake versus anesthetized. Seventy otherwise healthy patients between 2 and 8 yr of age were studied. Anesthesia was induced with halothane or thiamylal and maintained with nitrous oxide and halothane. After induction of anesthesia, the patients were randomly assigned to group 1 (awake extubation) or group 2 (anesthetized extubation). Oxygen saturation was measured continuously and recorded 10 min before extubation and at 1, 2, 3, 5, 7, 10, 15, 20, 25, and 30 min after tracheal extubation. Supplemental oxygen was administered when oxygen saturation values were less than 90% while breathing room air. Oxygen saturation levels were higher in group 2 than in group 1 at 1, 2, 3, and 5 min after extubation. There were no differences between the two groups in the number of patients requiring supplemental oxygen. The incidence of airway-related complications such as laryngospasm, croup, sore throat, excessive coughing, and arrhythmias was not different between the two groups. We conclude that the anesthesiologist's preference or surgical requirements may dictate the choice of extubation technique in otherwise healthy children undergoing elective surgery.     

Respiratory complications associated with tracheal extubationTiming of tracheal extubation and use of the laryngeal mask during emergence from anaesthesia

Sixty patients were randomly allocated to one of three groups and the incidences of respiratory complications which occurred during emergence from anaesthesia were compared under the following three circumstances: tracheal extubation after the patient had regained consciousness (awake group); tracheal extubation while the patient was still anaesthetised (anaesthetised group); and the use of the laryngeal mask during emergence from anaesthesia (mask group). In the mask group, the laryngeal mask was inserted under deep anaesthesia before tracheal extubation and the lungs were ventilated through the laryngeal mask after tracheal extubation. In the awake group, straining (bucking) occurred in 18 patients and desaturation (arterial oxygen haemoglobin saturation < 95%) in two patients. In the anaesthetised group, airway obstruction occurred in 17 patients and desaturation in one of these patients. In the mask group, ventilation through the laryngeal mask was temporarily difficult immediately after tracheal extubation in one patient and coughing occurred before removal of the mask in three patients. No respiratory complications occurred in two patients in the awake group, three patients in the anaesthetised group and 16 patients in the mask group. The incidence of respiratory complications during recovery from anaesthesia was significantly lower in the mask group than in the other two groups (pooled) (p << 0.001). Therefore, the use of the laryngeal mask after tracheal extubation decreases the incidence of respiratory complications during recovery from anaesthesia.     

Removal of the laryngeal tube in children: anaesthetized compared with awake

Background: Laryngeal tube (LT) is a useful airway device in children, butthere is no objective evidence that removal of LT in awake stateis better than in anaesthetized state. So, we compared the incidenceof respiratory adverse events after the removal of LT, eitherunder anaesthesia or on awakening. Methods: Seventy healthy children between 1 and 12 yr of age were enrolledin this study. Anaesthesia was induced and maintained with sevoflurane.After induction of anaesthesia, patients were randomized intotwo groups: removal of LT in anaesthetized state (Group A: 2%sevoflurane) and in awake state (Group B). During and within1 min of the removal of LT, airway complications such as upperairway obstruction, cough, vomiting, teeth clenching, hypersalivation,desaturation <90%, and laryngospasm were recorded. Results: Cough (37.1 vs 2.9%), hypersalivation (28.6 vs 5.7%), desaturation(20 vs 0%), and LT dislocation during emergence relating tothe patient's movement (26.5 vs 0%) occurred more frequentlyin Group B (P < 0.05). Upper airway obstruction occurredmore frequently (68.6 vs 31.4%) in Group A, and it was easilyresolved by chin or jaw lifting. Conclusion: LT removal in anaesthetized state reduced cough, hypersalivation,and prevented tube displacement and hypoxia. Upper airway obstructionin the anaesthetized state should be predicted and managed withchin or jaw lifting.     

Comparison between intubation and the laryngeal mask airway in moderately obese adults

Background: Obesity is a well-established risk factor for perioperative pulmonary complications. Anaesthetic drugs and the effect of obesity on respiratory mechanics are responsible for these pathophysiological changes, but tracheal intubation with muscle relaxation may also contribute. This study evaluates the influence of airway management, i.e. intubation vs. laryngeal mask airway (LMA), on postoperative lung volumes and arterial oxygen saturation in the early postoperative period.
Methods: We prospectively studied 134 moderately obese patients (BMI 30) undergoing minor peripheral surgery. They were randomly assigned to orotracheal intubation or LMA during general anaesthesia with mechanical ventilation. Premedication, general anaesthesia and respiratory settings were standardized. While breathing air, we measured arterial oxygen saturation by pulse oximetry. Inspiratory and expiratory lung function was measured preoperatively (baseline) and at 10 min, 0.5, 2 and 24 h after extubation, with the patient supine, in a 30° head-up position. The two groups were compared using repeated-measure analysis of variance (ANOVA) and t -test analysis. Statistical significance was considered to be P <0.05.
Results: Postoperative pulmonary mechanical function was significantly reduced in both groups compared with preoperative values. However, within the first 24 h, lung function tests and oxygen saturation were significantly better in the LMA group ( P <0.001; ANOVA).
Conclusions: In moderately obese patients undergoing minor surgery, use of the LMA may be preferable to orotracheal intubation with respect to postoperative saturation and lung function.