Effect of the laryngeal mask airway on oesophageal pH: influence of the volume and pressure inside the cuff

We studied gastro-oesophageal reflux (GOR) with a face mask and laryngeal mask airway (LMA), and the effects of inflation pressure and volume of the LMA cuff on oesophageal pH, in 60 patients. Patients were managed with either a face mask (group I) or LMA inflated to obtain a seal in the anaesthesia circuit at 7 cm H2O (group II) or 15 cm H2O (group III). A pH-sensitive probe with two electrodes, 10 cm apart, was placed in the oesophagus during anaesthesia and recordings were made continuously until patients awakened. There was a significant difference in the incidence of GOR between the face mask (group I) and the LMA (groups II-III) (P < 0.05) in the lower oesophagus but there was no difference in the mid-oesophagus. No correlation was found between pressure and volume inside the cuff and variations in oesophageal pH. We conclude that LMA use was associated with increased reflux in the low oesophagus but oesophageal pH was not influenced by variations in pressure or volume inside the LMA cuff.      

Use of the laryngeal mask airway as an alternative to a face mask during outpatient arthroscopy.

The laryngeal mask airway (LMA) has recently become available in the United States, and several authors have suggested that it is superior to an anesthesia mask. To test this hypothesis, 64 patients undergoing outpatient arthroscopic knee surgery were randomly assigned to have anesthesia maintained via either a laryngeal mask airway (LMA) (n = 31) or a standard face mask (n = 33). Anesthesia was induced with fentanyl 1 microgram.kg-1 and propofol 2 mg.kg-1 and maintained with a variable-rate propofol infusion (50-180 micrograms.kg-1 x min) and nitrous oxide 67% in oxygen. The LMA was inserted without difficulty by inexperienced anesthesiologists in 90% of the patients. Problems associated with airway management were more common in patients in the face mask (control) group. Episodes of hemoglobin oxygen desaturation (< 95%) occurred in 52% of patients in the face mask group compared to only 13% in the LMA group (P < 0.05). Intraoperative airway manipulations were required in 15% of face mask patients (vs. 3% of the LMA group), and difficulties in maintaining an airway were reported by 24% of the resident anesthesiologists caring for patients in the face mask group (vs. none in the LMA group) (P < 0.05). Insertion of the LMA was not associated with any acute changes in hemodynamic values. Intraoperative hemodynamic values and anesthetic requirements did not differ significantly between the two treatment groups. There were no significant differences in the emergence and recovery times or in the incidence of postoperative sore throats between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

The laryngeal mask airway. Safety, efficacy, and current use

In 1983, the laryngeal mask airway (LMA) was introduced as a new airway device. It can be inserted without the aid of a laryngoscope or neuromuscular blockade. Compared with the face mask, the LMA allows for a more "hands-free approach" to airway management providing the anesthesiologist the freedom of not holding a mask. In addition, the LMA is more effective than the face mask, with or without a Guedel airway, during emergency resuscitation in situations where endotracheal intubation is difficult or not possible. The LMA seems to provide better oxygenation than the face mask; but unlike the endotracheal tube, it does not protect the airway from aspiration of gastric contents if regurgitation occurs. For this reason, it is believed that the LMA should not be used in place of an endotracheal tube during emergency rescue, but rather as an adjunct to airway management prior to intubation. It is possible that the risk of regurgitation with or without aspiration may be minimized if proper screening of patients is employed prior to use of the LMA. The current literature concerning its safety and efficacy is reviewed.     

The laryngeal mask airway in obstetrical anaesthesia

The laryngeal mask airway (LMA) has been used extensively to provide a safe airway in spontaneously breathing patients who are not at risk from aspiration of gastric contents. The role of the LMA in the event of a failed intubation in an obstetrical patient, and its place in a failed intubation drill remains unclear. Two hundred and fifty consultant obstetric anaesthetists in the United Kingdom were asked to complete an anonymous questionnaire regarding their views about using the laryngeal mask airway (LMA) in obstetrical anaesthesia. The LMA was available in 91.4% of obstetric units. Seventy-two per cent of anaesthetists were in favour of using the LMA to maintain oxygenation when tracheal intubation had failed and ventilation using a face mask was inadequate. Twenty-four respondents had had personal experience with the LMA in obstetrical anaesthesia, eight of whom stated that the LMA had proved to be a lifesaver. We believe that the LMA has a role in obstetrical anaesthesia when tracheal intubation has failed and ventilation using a face mask proves to be impossible, and it should be inserted before attempting cricothyroidectomy.     

The proseal laryngeal mask airway in prone patients: a retrospective audit of 245 patients

The use of the classic laryngeal mask airway (classic LMA) in the prone position is controversial, but the ProSeal laryngeal mask airway (ProSeal LMA) may be more suitable as it forms a better seal and provides access to the stomach. In the following retrospective audit, we describe our experience with the insertion of and maintenance of anaesthesia with, the ProSeal LMA in 245 healthy adults in the prone position by experienced users. The technique involved (1) the patient adopting the prone position with the head to the side and the table tilted laterally; (2) pre-oxygenation to end-tidal oxygen >90%; (3) induction of anaesthesia with midazolam/alfentanil/propofol; (4) facemask ventilation (5) a single attempt at digital insertion and if unsuccessful a single attempt at laryngoscope-guided, gum elastic bougie-guided insertion; (6) gastric tube insertion; (7) maintenance of anaesthesia with sevoflurane/O/N2O; (8) volume controlled ventilation at 8-12 ml/kg; (9) emergence from anaesthesia in the supine position; and (10) removal ofthe ProSeal LMA when awake. Facemask ventilation was always successful. ProSealLMA insertion was successful in all patients: 237 with digital insertion and eight with bougie-guided insertion. Ventilation was successful in all patients. Gastric tube insertion was successful in all patients. Correctable partial airway obstruction occurred in three patients, but there was no hypoxia, hypercapnoea, displacement, regurgitation, gastric insufflation or airway reflex activation. Our findings suggest that the insertion of and maintenance of anaesthesia with the ProSeal LMA is feasible in the prone position by experienced users.     

The pressor response after laryngeal mask or cuffed oropharyngeal airway insertion

BACKGROUND: Since the cuffed oropharyngeal airway (COPA) has been suggested to cause less pharyngeal trauma than the laryngeal mask airway (LMA), we conducted a prospective, randomised study to compare haemodynamic changes after placing either the COPA or LMA in healthy anaesthetised adults. METHODS: After standard midazolam premedication (0.05 mg kg(-1) IV), general anaesthesia (IV propofol 2 mg kg(-1)) was induced in 60 ASA physical status I-II, 18-65-yr-old patients, who were randomly allocated to receive COPA (n=30) or LMA (n= 30) placement and then mechanically ventilated using a 60% nitrous oxide and 1% isoflurane in oxygen mixture (TV=8 ml kg(-1), RR=12 b.p.m., I/E=1/2). Haemodynamic variables were recorded 20 min after the midazolam premedication (baseline), and then every 1 min until 10 min after general anaesthesia induction. RESULTS: Nine patients of group COPA (30%) required chin lift, jaw thrust or head tilt to maintain adequate ventilation, while no problems were observed in the LMA group (P<0.0005); however, in no case did the designed extratracheal airway have to be removed due to unsuccessful mechanical ventilation, and no signs of gastric insufflation or regurgitation were reported. The maximum mean changes in haemodynamic variables were more marked after LMA placement (SAP: 12%+/-13%; DAP: 11%+/-18%; HR: 13%+/-16%) than COPA placement (SAP: -3%+/-18%; DAP: -5%+/-16%; HR: 4%+/-13%) (P<0.005, P<0.005, and P<0.01 for SAP, DAP and HR, respectively). Group LMA showed higher SAP and DAP values than group COPA only during the first 3 min after airway insertion. CONCLUSION: In healthy, anaesthetised patients, placing a cuffed oropharyngeal airway is associated with smaller cardiovascular changes after airway insertion compared with the laryngeal mask airway.     

The site of airway irritation during induction of anaesthesia

The aim of this investigation was to study the role of the nasal airway in mediating upper airway reflexes during induction of anaesthesia when the commonly used irritant inhalational anaesthetic agent enflurane is used. In a prospective randomised study, 40 ASA 1 & 2 day-case patients undergoing body surface surgery were recruited. Following intravenous induction using propofol, 20 patients received enflurane administered via a laryngeal mask airway (LMA), the anaesthetic vapour therefore bypassing the nasal airway. In the other group, 20 patients received enflurane anaesthesia administered using a face mask, the nasal airway therefore being exposed to inhalation anaesthetic. We were unable to demonstrate any significant (p < 0.05) differences between the two groups in relation to upper airway complications (cough, breath holding, laryngeal spasm, bronchospasm and excitement). Previous work has identified the nose as a possible important reflexogenic site for upper airway reflexes in humans during anaesthesia. We have been unable to demonstrate any difference in upper airway complications when the nasal airway was included or excluded from exposure to irritant anaesthetic vapours, when administered in a clinical setting.     

Regurgitation and aspiration of gastric contents in a child during general anaesthesia using the laryngeal mask airway

We present a case report of a child who underwent general anaesthesia for elective surgery in whom regurgitation and aspiration of gastric contents were associated with the use of the laryngeal mask airway (LMA). Bronchospasm developed but mechanical ventilation was not required. The possible mechanisms causing regurgitation are discussed.     

Comparison of the Intersurgical SolusTM laryngeal mask airway and the i‐gel supralaryngeal device

We compared the performance of the Intersurgical Solus^TM laryngeal mask airway (LMA) with that of the i‐gel in 120 patients of ASA physical status during general anaesthesia with respect to oropharyngeal leak pressure, peak airway pressure, airway manipulation, insertion time, fibreoptic view, ventilatory parameters, and peri‐operative complications . After receiving a standardised induction of anaesthesia, either a Solus LMA (60 patients) or an i‐gel (60 patients) was inserted. One hundred and fifteen patients completed the study. The leak pressure was significantly higher in the LMA group than the i‐gel group (mean (SD) 22.7 (7.7) cmH₂O vs 19.3 (7.1) cmH₂O; p = 0.02). A better fibreoptic view of the larynx was obtained in patients in the LMA group (p = 0.02) compared to those in the i‐gel group and less airway manipulation was required in the LMA group (p < 0.01). Both devices have good performance with very low peri‐operative complications . However, the Solus LMA provides a better oropharyngeal seal, provides a better fibreoptic view, and requires less manipulation to secure the airway than the i‐gel.     

Risk factors for airway complications during general anaesthesia in paediatric patients

BACKGROUND: Although airway complications are a frequent problem during paediatric anaesthesia, no study has prospectively identified risk factors for adverse respiratory events during airway management when LMA trade mark (laryngeal mask airway), face mask (FM) or a tracheal tube (TT) are used. METHODS: A prospective study was performed at a university hospital's paediatric centre. Preoperative information included recent history of respiratory infection and type of surgery. Intraoperative information included the identification of the device user, the duration of anaesthesia and the type of airway device used. Adverse respiratory events during the perioperative and postoperative periods were registered. One thousand nine hundred and ninety-six patients were included (mean age 6.45 +/- 2.9 years). RESULTS: Airway complications occurred in 10.2% of the patient for LMA (72/704), 4.7% for FM (19/401) and 7.4% (66/891) for TT. Using a stepwise logistic regression, three independent risk factors were identified: age < 6 years, odds ratio (OR) 1.84, 95% CI (1.21-2.80); use of LMA, OR 2.32, 95% CI (1.29-4.17); presence of respiratory infections (RI) before the procedure, OR 3.72, 95% CI (2.3-5.99). CONCLUSIONS: Age < 6 years, recent RI and the use of the LMA were identified as independent factors associated with an increased risk of airway complications.     

Risk of aspiration with the laryngeal mask

In order to assess if the use of the laryngeal mask airway isassociated with an increased risk of gastric regurgitation duringmechanical ventilation, we studied 50 patients allocated randomlyto undergo anaesthesia with either artificial ventilation withisoflurane and nitrous oxide in oxygen and atracurium (groupA) or spontaneous ventilation with isoflurane and nitrous oxidein oxygen (group B). In both groups a laryngeal mask airwaywas used. Regurgitation was assessed by the patient ingestinga meth ylene blue capsule 10 min before induction of anaesthesiaand examining the oropharynx by direct laryngoscopy at the endof surgery. In one patient in each group, there was stainingof the oropharynx with blue dye at the end of surgery. In thepatient in group A, dye was present in the trachea and bronchi.(Br. J. Anaesth. 1994; 72: 447–450)     

Gas leak and gastric insufflation during controlled ventilation: face maskversus laryngeal mask airway

Purpose

To compare two airway management techniques, face mask (FM) with oropharyngeal airway and laryngeal mask airway (LMA), with respect to the effectiveness of positive pressure ventilation and airway maintenance.

Methods

After induction of anaesthesia, two airway management techniques (FM or LMA) and three peak pressures (20, 25 and 30 cm H₂O) were randomly applied during controlled ventilation in 60 patients. Data collected included inspiratory and expiratory volumes and presence of gastro-oesophageal insufflation. Leak was calculated by subtracting the expiratory from the inspiratory volume, expressed as a fraction of the inspiratory volume.

Results

Expiratory volumes (mean ± SD) at 20, 25 and 30 cm H₂O for LMA ventilation were 893 ± 260, 986 ± 276 and 1006 ± 262 respectively, and for FM ventilation 964 ± 264, 1100 ± 268 and 1116 ± 261. Leak fractions at 20, 25 and 30 cm H₂O for LMA ventilation were 0.21 ± 0.15, 0.24 ± 0.18 and 0.26 ± 0.18 respectively, and for FM ventilation 0.14 ± 0.09, 0.14 ± 0.09 and 0.12 ± 0.08. The frequency of gastro-oesophageal insufflation was 1.6%, 5% and 5% for the LMA and 5%, 15% and 26.6% for the FM for ventilation pressures of 20, 25 and 30 cm H₂O respectively which was greater with LMA use.

Conclusion

Ventilation was adequate in all patients using both techniques. Leak was pressure dependent and greater with LMA use. Most of the leak was vented to the atmosphere via the pharynx. Gastro-oesophageal insufflation was more frequent with ventilation using the face mask. LMA use with positive pressure ventilation would appear to be a better airway management method than the face mask.     

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.     

A randomised controlled trial comparing two insertion techniques for the Laryngeal Mask Airway Flexible™ in patients undergoing dental surgery

The Laryngeal Mask Airway Flexible^TM (LMA Flexible) has been widely utilised for dental, ophthalmology and otorhinolaryngology‐related procedures. Our study evaluates two different techniques of inserting the LMA Flexible for patients undergoing day‐case dental surgery. One hundred and eight patients were randomly assigned into two groups based on the LMA Flexible insertion technique – either laryngoscopy‐guided (n = 54) or digital manipulation (standard technique; n = 54). Patient and airway characteristics were recorded before induction of anaesthesia. The primary outcome was success rate at first insertion. Other outcomes assessed included fibreoptic assessment of laryngeal mask airway placement, haemodynamic changes, need for airway adjustment during surgery and sore throat. The success rate of insertion on the first attempt was higher for the laryngoscopy‐assisted technique compared with the standard technique (96.3% vs 81.5%, respectively, p < 0.05). Fibreoptic assessment showed that the former group had better placement of the laryngeal mask airway than the latter (59.3% vs 37% p < 0.05). There were no significant differences between the two groups for haemodynamic changes. Sore throat was more common in the group with the standard technique (35.2% vs 16.7%, p < 0.05). Our study suggests the use of the laryngoscope to guide insertion of the LMA Flexible for dental surgery is a better option compared with the standard technique of digital manipulation.     

Fiberoptic determination of the position of the laryngeal mask]

The laryngeal mask airway (LMA) provides a patent airway when placed 'blindly' into the hypopharynx. At the laryngeal side it is supposed to form a seal surrounding the laryngeal inlet with the epiglottis lying outside the mask aperture. This study is designed to assess the prelaryngeal position of the mask by the fibreoptic technique. METHODS. After approval by the local ethical committee and informed consent, 100 adult patients (ASA groups I and II) undergoing general anaesthesia for extracorporal stroke wave lithotripsy (ESWL, Lithotripter HM 3, Dornier) of the kidney were studied. Anaesthesia was induced with propofol (1.5-2.5 mg.kg-1) and fentanyl (1-1.5 micrograms.kg-1) and maintained with isoflurane and N2O (65% in O2) as clinically indicated. The LMA was left in situ until the patients opened their mouth on command. Monitoring consisted of an ECG (SMV 104-D, Dornier), a pulse oximeter (Nellcor 200, Draeger), and a non-invasive blood pressure monitor (BP 103 N, Hoyer). Clinical assessment of airway patency and fibreoptic laryngoscopy (BF Typ 10, Olympus)--immediately and 20 min following the insertion of the LMA--were performed by two observers. RESULTS. The insertion of the LMA was successful on the first attempt in 89 patients while 5% required two, 4% three and 2% four attempts. 'Blindly' inserted without neuromuscular blockade the LMA provided a clinically sufficient airway in all patients. A central position of the LMA was assessed in only 59% of the cases. In 4 patients the mask was riding on the vocal folds. Positioned at the posterior larynx the cuff produced a compression of the laryngeal orifice when insufflated. Oblique insertion of the LMA or oblique head position during insertion produced a misplacement of the LMA. In 5 cases the LMA followed lateral movements of the head without losing its central position. In 87% the epiglottis was within the lumen of the LMA. Secretions inside the mask lumen or at the anatomic structures were seen in 36%. During manual ventilation with high inspiratory pressure (> 25 cm H2O) the oesophagus opened in 10 cases. CONCLUSIONS. Previous studies have suggested that the LMA takes a 'perfect' position at the laryngeal side when a clinically patent airway is recognized. In contrast, our results demonstrated that a central position of the LMA is achieved in only 59% of the cases. Our results indicate that epiglottic downfolding or left/right side or anterior/posterior misplacement are common but generally provide a satisfactory patent airway. This is consistent with fibreoptic findings in children and radiological observations in adults. The LMA is an essential enrichment to conventional airway management. It provides a better seal than the face mask, especially in bearded or in old patients where the facial contours are often not suited to the mask. Ideal indications seem to be elective operations of intermediate duration (1-2 h). The LMA does not protect against aspiration. For patients who are at risk of regurgitation of gastric contents, use of the LMA is absolutely contraindicated. Relative contraindications are local pathology of the pharynx and situations with low pulmonary compliance and/or high airway resistance (massive obesity, asthma, etc.), especially during controlled ventilation. Further studies are necessary to establish definite indications for the application of the LMA.     

Anaesthesia for adenotonsillectomy: A comparison between tracheal intubation and the armoured laryngeal mask airway

A prototype armoured laryngeal mask airway (LMA) was compared with tracheal intubation (ETT) for anaesthesia for adenotonsillectomy. Fifty-five children were randomised into the LMA group and 54 into the ETT group. During insertion of the LMA, peripheral oxyhaemoglobin desaturation (SpO₂) < 94% occurred in ten patients (18.2%) and in seven patients (13%) during tracheal intubation (NS). After opening the Boyle-Davis gag, airway obstruction occurred in ten patients (18.2%) in the LMA group and in three patients (6%) in the ETT group (P = 0.07). In five patients (9%) the LMA was abandoned in favour of tracheal intubation. In all others (91%), when the need for adequate depth of anaesthesia was realized, a satisfactory airway was achieved more rapidly than with tracheal intubation (P < 0.001), and maintained throughout surgery. Manually assisted ventilation was required in all patients in the ETT group, mean duration 373 ± 385 sec, and in 26 patients (52%) in the LMA group, mean duration 134 ± 110 sec, P < 0.001. Mean end-tidal CO₂ (PetCO₂) was 45.5 ± 6.21 mmHg in the ETT group and 46.6 ± 6.09 in the LMA group (NS). The LMA did not limit surgical access. Heart rate, MAP and blood loss in the LMA group were 110 ± 21, 74 ± 9 mmHg and 1.92 ± 1.22 ml · kg^?1 respectively, compared with 143 ± 13 (P < 0.001), 85 ± 12 mmHg (P < 0.001) and 2.62 ± 1.36 ml · kg^?1 (P < 0.05) with tracheal intubation. Fibreoptic laryngoscopy at the end of surgery in 19 patients in the LMA group revealed no blood in the larynx. In the LMA group postintubation stridor and laryngospasm occurred in five and three patients respectively, compared with 14 (P < 0.05) and six patients respectively (NS) with tracheal intubation. SpO₂ on admission to the PACU in the LMA group was 95.9 ± 2.21, and 93.5 ± 4.53 (P < 0.05) after tracheal intubation. Our study demonstrated that the LMA is a safe alternative to tracheal intubation for adenotonsillectomy. Control of airway reflexes by ensuring sufficient depth of anaesthesia is essential for successful use of the LMA in children.     

Do laryngeal mask airway devices attenuate liquid flow between the esophagus and pharynx? A randomized, controlled cadaver study

In this randomized, controlled cadaver study, we tested the hypothesis that the standard laryngeal mask airway (LMA) and flexible laryngeal mask airway (FLMA) attenuate liquid flow between the esophagus and pharynx. Fifty fresh cadavers were studied in four LMA groups. Ten female cadavers had a size 4 LMA and 10 had a size 4 FLMA; 10 male cadavers had a size 5 LMA and 10 had a size 5 FLMA; 5 male and 5 female cadavers functioned as controls. The chest was opened, and the infusion set of a pressure-controlled, continuous flow pump was inserted into the esophagus and ligated into place. Esophageal pressure was increased in 2-cm H2O increments. Regurgitation pressure was the esophageal pressure at which fluid was first seen with a fiberoptic scope in the hypopharynx (control group) and above the cuff or within the bowl (LMA groups). This was performed in the LMA groups at 0-40 mL cuff volume in 10-mL increments. Mean (95% confidence interval) regurgitation pressure for the control group was 7 (6-8) cm H2O and for the LMA groups combined was 19 (17-20) cm H2O at 0 mL cuff volume, 47 (41-52) cm H2O at 10 mL, 51 (44-55) cm H2O at 20 mL, 52 (45-56) cm H2O at 30 mL, and 52 (45-55) cm H2O at 40 mL. The increase in regurgitation pressure with increasing cuff volume from 0 to 10 mL was statistically significant (P < 0.0001). Regurgitation pressure was higher for the LMA groups at all cuff volumes compared with the control group (P < 0.0001). There were no differences in regurgitation pressure among the LMA groups. We conclude that the correctly placed LMA and FLMA attenuate liquid flow between the esophagus and pharynx. Implications: We have shown, in cadavers, that the correctly placed standard and flexible laryngeal mask airways attenuate liquid flow between the pharynx and esophagus.     

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.     

Removal of laryngeal mask airway: airway complications in children,anaesthetized versus awake*

The laryngeal mask airway (LMA) must be inserted during deep anaesthesia. There are no guidelines concerning the removal of LMA, i.e., in awake or anaesthetized patients. The aim of this randomized prospective study was to compare the incidence of respiratory complications after LMA removal in anaesthetized or awake paediatric patients. Sixty children (ASA PS I or II), ranging from 4 months to 12 years of age, were studied. In patients breathing spontaneously, anaesthesia was induced and maintained with nitrous oxide, oxygen and halothane. Patients were randomly divided into two groups: group 1 removal of LMA in awake patients, or group 2 removal of LMA in anaesthetized patients, i.e., in patients receiving halothane at an alveolar concentration of 2 MAC adjusted for age and oxygen for 5 min. In both groups, patients received 100% oxygen after removal of LMA. After removal the incidence of respiratory complications was highest (P < 0.05) in group 1. Therefore, in healthy children undergoing elective surgery, the authors conclude that it is safer to perform the LMA removal in anaesthetized patients.     

Efficacy and safety of the laryngeal mask airwayvs Guedel airway following tracheal extubation

PURPOSE: To compare the safety and efficacy of the laryngeal mask airway (LMA) with the Guedel airway during the recovery period. METHODS: In a prospective randomised trial in the Post Anesthesia Care Unit (PACU), 52 patients (ASA 1 and 2) were randomised to receive either a laryngeal mask airway (LMA: n = 26) or a Guedel airway (n = 26) during the recovery period after middle ear surgery. Ease of airway maintenance was graded and the presence of coughing was noted. Peripheral arterial oxygen saturation (SpO2) was measured continuously by pulse oximetry in the PACU. Readings were taken on arrival (time 0) and for five minutes afterwards. RESULTS: There was no difference in sex, age, weight or incidence of smoking between the two groups. In the LMA group 25 patients required no airway manipulation and only one patient required repositioning of the LMA. In the Guedel group severe difficulty maintaining the airway was experienced in two patients, moderate difficulty in five patients and mild difficulty in 12 patients. Seven patients required no airway manipulation. The LMA group showed higher ease of airway maintenance scores, (P = < 0.0001) and less coughing (P = 0.0496). At time 0 and at one minute the LMA group had higher median SpO2 (97% and 97%) than the Guedel group (95% and 96%), (P = 0.0002 and 0.0362). There was no further difference in SpO2. CONCLUSIONS: The LMA provides easier airway maintenance, less coughing and initially higher median SpO2 when compared with the Guedel airway in the recovery period.