J. Brimacombe

Survey of Laryngeal Mask Airway Usage in 11,910 Patients: Safety and Efficacy for Conventional and Nonconventional Usage

A survey of laryngeal mask airway (LMA) usage was conducted to provide general information about safety and efficacy with special emphasis on controversial issues such as positive pressure ventilation (PPV), prolonged anesthesia, and laparoscopic and nonlaparoscopic intraabdominal surgery.During the 2-yr study period, of the 39,824 patients who underwent general anesthesia, 11,910 (29.9%) patient airways were managed with the LMA. Forty-four percent underwent PPV. Placement was successful in 99.81%, and in 23 patients the LMA was abandoned in favor of the tracheal tube (TT). Use of the LMA for any intraabdominal procedure was considered nonconventional and occurred in 2222 (18.7%) patients. On 579 occasions procedures lasted >2 h. A total of 44 critical incidents were documented. Eighteen (0.15%) were related to the airway and none required intensive care management. There were 26 critical incidents not related to the airway which resulted in two admissions to the intensive care unit and one death. There were three cases of failed tracheal intubation managed with the LMA. This survey demonstrates that the LMA technique is safe and effective for both spontaneous and controlled ventilation. Use of the LMA for gynecologic laparoscopy, gynecologic laparotomy, and procedures >2 h also appears safe. (Anesth Analg 1996;82:129-33)

The incidence of aspiration associated with the laryngeal mask airway: a meta-analysis of published literature.

STUDY OBJECTIVE To determine the incidence of pulmonary aspiration with the laryngeal mask airway (LMA). DESIGN A meta-analysis of all published literature on the LMA to September 1993. MEASUREMENTS AND MAIN RESULTS All 547 publications were reviewed and coded, and those observational studies in which the LMA was the main form of airway management were analyzed. Pulmonary aspiration was defined as either the presence of bilious secretions or particulate matter in the tracheobronchial tree or, if bronchoscopy was not performed, a postoperative chest radiograph with infiltrates present on preoperative chest radiograph of physical examination. In the study population, there were 3 cases of aspiration in 12,901 patients, and when combined with four independent reports excluded from the detailed analysis, this gave a final incidence of 2 in 10,000. Ten confirmed pulmonary aspiration events from published case reports showed that most cases had one or more predisposing factors. No death of permanent disability occurred. CONCLUSIONS The evidence to date suggests that the pulmonary aspiration with the LMA is uncommon and comparable to that for outpatient anesthesia with the face mask and tracheal tube. Meticulous attention to selection of low-risk patients and appropriate operative procedures and avoidance of light anesthesia should reduce the incidence even further.

The ProSeal laryngeal mask airway : A randomized, crossover study with the standard laryngeal mask airway in paralyzed, anesthetized patients

Background The ProSeal laryngeal mask airway (PLMA) is a new laryngeal mask device with a modified cuff to improve seal and a drainage tube to provide a channel for regurgitated fluid and gastric tube placement. In the present randomized, crossover study, the authors tested the hypothesis that ease of insertion, airway sealing pressure, and fiberoptic position differ between the PLMA and the standard laryngeal mask airway (LMA). For the PLMA, we also assess ease of gastric tube placement and the efficacy of an introducer tool. Methods Sixty paralyzed, anesthetized adult patients were studied. Both devices (only size 4) were inserted into each patient in random order. Airway sealing pressure and fiberoptic position were determined during cuff inflation from 0 to 40 ml in 10-ml increments. Gastric tube insertion was attempted with the PLMA if there was no gas leak from the drainage tube. In 60 additional patients, ease of insertion for the PLMA was compared with and without an introducer. Results First-time success rates were higher (60 of 60 vs. 52 of 60;P = 0.003) and the effective airway time shorter (9 ± 3 s vs 20 ± 18 s;P < 0.0001) for the LMA. There were no failed uses of either device within three attempts. Airway sealing pressure was 8–11 cm H2O higher for the PLMA at all cuff volumes (P < 0.00001) and was higher in females for both devices. Fiberoptic position was better with the LMA at all cuff volumes (P < 0.00001), but vocal cord visibility was similar (LMA, 59 of 60; PLMA, 56 of 60). For the PLMA, gastric tube placement was successful in 58 of 58 patients and took 9 ± 5 s. First-time success rates were higher (59 of 60 vs 53/60;P = 0.03) and the effective airway time shorter (15 ± 13 s vs 23 ± 18 s;P = 0.008) with the introducer. Conclusion The PLMA is capable of achieving a more effective seal than the LMA and facilitates gastric tube placement, but it is more difficult to insert unless an introducer tool is used. When correctly positioned, the PLMA isolates the glottis from the upper esophagus with possible implications for airway protection.

The advantages of the LMA over the tracheal tube or facemask: a meta-analysis

A meta-analysis was performed on randomised prospective trials comparing the laryngeal mask airway (LMA) with other forms of airway management to determine if the LMA offered any advantages over the tracheal tube (TT) or facemask (FM). Of the 858 LMA publications identified to December 1994, 52 met the criteria for the analysis. Thirty-two different issues were tested using Fisher’s method for combining the P values. The LMA has 13 advantages over the TT and four over the FM. The LMA had two disadvantages over the TT and one over the FM. There were 12 issues where neither device had an advantage. Advantages over the TT included: increased speed and ease of placement by inexperienced personnel; increased speed of placement by anaesthetists; improved haemodynamic stability at induction and during emergence; minimal increase in intraocular pressure following insertion; reduced anaesthetic requirements for airway tolerance; lower frequency of coughing during emergence; improved oxygen saturation during emergence; and lower incidence of sore throat in adults. Advantages over the FM included: easier placement by inexperienced personnel; improved oxygen saturation; less hand fatigue; and improved operating conditions during minor paediatric otological surgery. Disadvantages over the TT were lower seal pressures and a higher frequency of gastric insufflation. The only disadvantage compared with the FM was that oesophageal reflux was more likely. The importance of these findings in terms of patient outcome could not be determined from the published data.RésuméUne méta-analyse d’études randomisés et prospectives comparant le masque laryné (ML) avec les autres modes de gestion des voies aériennes a été réalisée dans le but de déterminer si le ML présentait des avantages sur le tube trachéal (TT) et le masque facial (MF). Des 858 publications portant sur le ML compilées jusqu’en décembre 1994, 52 ont rencontré les critères de l’analyse. Trente-deux parutions différentes ont été analysées avec la méthode de Fisher pour la combinaison des valeurs de P. Le ML possédait 13 avantages sur le TT et quatre sur le MF. Le ML possédait deux désavantages sur le TT et un sur le MF. Dans douze parutions, aucun des dispositifs n’offrait un seul avantage sur les autres dispositifs. Les avantages du ML sur le TT comprenaient: l’augmentation de la vitesse et de la facilité d’insertion par du personnel inexpérimenté; l’augmentation de la vitesse d’insertion par l’anesthésiste; l’amélioration de la stabilité hémodynamique à l’induction et au réveil; l’amélioration de la saturation en oxygéne à la phase de réveil; et une plus faible incidence de maux de gorge. Les avantages sur le MF étaient: la facilité de mise en place par le personnel inexpérimenté; l’amélioration de la saturation en oxygène; une fatigue moindre pour la main; l’amélioration de conditions chirurgicales pendant la chirurgie pédiatrique mineure. Les désavantages sur le TT étaient la baisse de la pression d’étanchéité et une augmentation de la fréquence de l’insufflation gastrique. Le seul désavantage sur le MF était une plus grande susceptibilité au reflux oesophagien. L’importance de ces constatations sur le devenir du patient n’a pu être déterminée à partir des données publiées.

A multicenter study comparing the ProSealTM and ClassicTM laryngeal mask airway in anesthetized, nonparalyzed patients

Background The laryngeal mask airway ProSeal™ (PLMA™), a new laryngeal mask device, was compared with the laryngeal mask airway Classic™ (LMA™) with respect to: (1) insertion success rates and times; (2) efficacy of seal; (3) fiberoptically determined anatomic position; (4) orogastric tube insertion success rates and times; (5) total intraoperative complications; and (6) postoperative sore throat in nonparalyzed adult patients undergoing general anesthesia, hypothesizing that these would be different. Methods Three hundred eighty-four nonparalyzed anesthetized adult patients (American Society of Anesthesiologists physical status I–II) were randomly allocated to the PLMA™ or LMA™ for airway management. In addition, 50% of patients were randomized for orogastric tube placement. Unblinded observers collected intraoperative data, and blinded observers collected postoperative data. Results First-attempt insertion success rates (91 vs. 82%, P = 0.015) were higher for the LMA™, but after three attempts success rates were similar (LMA™, 100%;PLMA™, 98%). Less time was required to achieve an effective airway with the LMA™ (31 ± 30 vs. 41 ± 49 s;P = 0.02). The PLMA™ formed a more effective seal (27 ± 7 vs. 22 ± 6 cm H2O;P < 0.0001). Fiberoptically determined anatomic position was better with the LMA™ (P < 0.0001). Orogastric tube insertion was more successful after two attempts (88 vs. 55%;P < 0.0001) and quicker (22 ± 18 vs. 38 ± 56 s) with the PLMA™. During maintenance, the PLMA™ failed twice (leak, stridor) and the LMA™ failed once (laryngospasm). Total intraoperative complications were similar for both groups. The incidence of postoperative sore throat was similar. Conclusion In anesthetized, nonparalyzed patients, the LMA™ is easier and quicker to insert, but the PLMA™ forms a better seal and facilitates easier and quicker orogastric tube placement. The incidence of total intraoperative complications and postoperative sore throat are similar.

Does the ProSeal Laryngeal Mask Airway Prevent Aspiration of Regurgitated Fluid

In this randomized, cross-over cadaver study, we determined whether a new airway device, the ProSeal laryngeal mask airway (PLMA; Laryngeal Mask Company, Henley-on-Thames, UK), prevents aspiration of regurgitated fluid. We studied five male and five female cadavers (6–24 h postmortem). The infusion set of a pressure-controlled, continuous flow pump was inserted into the upper esophagus and ligated into place. Esophageal pressure (EP) was increased in 2-cm H2O increments. This was performed without an airway device (control) and over a range of cuff volumes (0–40 mL) for the classic laryngeal mask airway (LMA), the PLMA with the drainage tube clamped (PLMA clamped) and unclamped (PLMA unclamped). The EP at which fluid was first seen with a fiberoptic scope in the hypopharynx (control), above or below the cuff, or in the drainage tube, was noted. Mean EP at which fluid was seen without any airway device was 9 (range 8–10) cm H2O. EP at which fluid was seen was always higher for the PLMA clamped and LMA compared with the control (all, P < 0.0001). The mean EP at which fluid was seen for the PLMA unclamped was similar to the control at 10 (range 8–13) cm H2O. For the PLMA unclamped, fluid appeared from the drainage tube in all cadavers at 10–40 mL cuff volume and in 8 of 10 cadavers at zero cuff volume. Mean EP at which fluid was seen above the cuff was similar for the PLMA clamped and LMA at 0–30 mL cuff volume, but was higher for PLMA clamped at 40-mL cuff volume (81 vs 48 cm H2O, P = 0.006). Mean EP at which fluid was seen below the cuff was similar at 0–10 mL cuff volume, but was higher for the PLMA clamped at 20, 30, and 40 mL cuff volume (62, 68, 73 vs 46, 46, 46 cm H2O, respectively, P < 0.04). For the PLMA clamped and the LMA, fluid appeared simultaneously above and below the cuff at all cuff volumes. We concluded that in the cadaver model, the correctly placed PLMA allows fluid in the esophagus to bypass the pharynx and mouth when the drainage tube is open. Both the LMA, and PLMA with a closed drainage tube, attenuate liquid flow between the esophagus and pharynx. This may have implications for airway protection in unconscious patients. Implications The correctly placed ProSeal laryngeal mask airway allows fluid in the esophagus to bypass the oropharynx in the cadaver model. This may have implications for airway protection in unconscious patients.

Analysis of 1500 laryngeal mask uses by one anaesthetist in adults undergoing routine anaesthesia.

An analysis of 1500 laryngeal mask airway uses by one anaesthetist using the standard insertion technique was conducted to determine successful insertion rates, position by fibreoptic laryngoscopy, complication rates and whether there is a long‐term learning curve. The correlation between laryngeal mask airway placement and modified Mallampati grade was also determined. The first time insertion rate was 95.5% with an overall failure rate after three attempts of 0.4%. One hundred and fifteen patients were Mallampati III or IV. All failed placements were Mallampati I or II. Problems occurred in 94 patients (6.27%), but oxygen saturation decreased below 90% on only ten occasions and below 80% on one occasion. There were no episodes of regurgitation. The vocal cords were visible from the mask aperture bars in 97.1%. Comparison of insertion rates, fibreoptic position and complications for the first and second 750 insertions provides evidence for a‘long’term learning curve. These data could he used as a guide for‘optimal’or expected successful laryngeal mask airway insertion rates in adults undergoing routine anaesthesia.

Gum Elastic Bougie-guided Insertion of the ProSeal™ Laryngeal Mask Airway Is Superior to the Digital and Introducer Tool Techniques

BackgroundThe authors compare three techniques for insertion of the ProSeal ™ laryngeal mask airway. MethodsTwo hundred forty healthy patients aged 18–80 yr were randomly allocated for ProSeal ™ laryngeal mask airway insertion using the digital, introducer tool (IT), or gum elastic bougie (GEB)-guided techniques. The digital and IT techniques were performed according to the manufacturer’s instructions. The GEB-guided technique involved priming the drain tube with the GEB, placing the GEB in the esophagus under direct vision, and inserting the ProSeal ™ laryngeal mask airway using the digital technique with the GEB as a guide. Failed insertion was defined by any of the following criteria: (1) failed pharyngeal placement; (2) malposition (air leaks, negative tap test results, or failed gastric tube insertion if pharyngeal placement was successful); and (3) ineffective ventilation (maximum expired tidal volume < 8 ml/kg or end-tidal carbon dioxide > 45 mmHg if correctly positioned). Any visible or occult blood was noted. Sore throat, dysphonia, and dysphagia were assessed 18–24 h postoperatively. ResultsInsertion was more frequently successful with the GEB-guided technique at the first attempt (GEB, 100%; digital, 88%; IT, 84%; both P < 0.001), but success after three attempts was similar (GEB, 100%; digital, 99%; IT, 98%). The time taken to successful placement was similar among groups at the first attempt but was shorter for the GEB-technique after three attempts (GEB, 25 ± 14 s; digital, 33 ± 19 s; IT, 37 ± 25 s; both:P < 0.003). There were no differences in the frequency of visible blood, but occult blood occurred less frequently with the GEB-guided technique (GEB, 12%; digital, 29%; IT, 31%; both:P < 0.02) but was similar among techniques if insertion was successful at the first attempt. There were no differences in postoperative airway morbidity. ConclusionThe GEB-guided insertion technique is more frequently successful than the digital or IT techniques. The authors suggest that the GEB-guided technique may be a useful backup technique for when the digital and IT techniques fail.

Cervical Spine Motion During Airway Management: A Cinefluoroscopic Study of the Posteriorly Destabilized Third Cervical Vertebrae in Human Cadavers

We conducted a randomized, controlled, crossover study to determine cervical spine motion for six airway management techniques in human cadavers with a posteriorly destabilized third cervical (C-3) vertebra. A destabilized C-3 segment was created in 10 cadavers (6–24 h postmortem). Cervical motion was recorded by continuous lateral fluoroscopy. The following airway management techniques were performed in random order on each cadaver with manual in-line stabilization applied: face mask ventilation (FM), laryngoscope-guided orotracheal intubation (OETT), fiberscope-guided nasal intubation (FOS-NETT), esophageal tracheal Combitube® (Kendall-Sheridan, Neustadt, Germany) insertion (ETC), intubating laryngeal mask insertion with fiberscope-guided tracheal intubation (ILM-OETT), and laryngeal mask airway insertion (LMA). Afterward, maximum head-neck flexion (FLEX-MAX) and maximum head-neck extension (EXT-MAX) without manual in-line stabilization was performed to determine maximum motion. The maximum posterior displacement of C-3 and the maximum segmental sagittal motion of C2-3 were determined. There was a significant increase in posterior displacement for the FM (1.9 ± 1.2 mm, P < 0.01), OETT (2.6 ± 1.6 mm, P < 0.0001), ETC (3.2 ± 1.6 mm, P < 0.0001), ILM-OETT (1.7 ± 1.3 mm, P < 0.01), LMA (1.7 ± 1.3 mm, P < 0.01), FLEX-MAX (3.7 ± 1.9 mm, P < 0.0001), EXT-MAX (1.8 ± 1.7, P < 0.01), however, not for FOS-NETT (0.1 ± 0.7 mm). Posterior displacement was less for the ILM-OETT and LMA than for the ETC (both P < 0.04). There were no significant increases in segmental sagittal motion with any airway manipulation other than with FLEX-MAX (−4.5 ± 4.0°, P < 0.01). Posterior displacement was similar to FLEX-MAX for the OETT and ETC; however, it was less for the FM, FOS-NETT, ILM-OETT, and LMA (all P < 0.01). Posterior displacement was similar to EXT-MAX for all airway manipulations other than for FOS-NETT (P < 0.001). For cervical motion and the techniques tested, the safest method of airway management in a patient with a posteriorly destabilized C-3 segment is FOS-NETT. LMA devices may be preferable to the ETC. Implications In the cadaver model of a destabilized third cervical vertebrae, significant displacement of the injured segment occurs during airway management with the face mask, laryngoscope-guided oral intubation, the esophageal tracheal Combitube® (Kendall-Sheridan, Neustadt, Germany), the intubating and standard laryngeal mask airway; but not with fiberscope-guided nasal intubation. For cervical motion and the techniques tested, the safest airway technique with this injury is fiberscope-guided nasotracheal intubation. Laryngeal mask devices are preferable to the esophageal tracheal Combitube®.

The Laryngeal Mask Airway ProSeal™ as a Temporary Ventilatory Device in Grossly and Morbidly Obese Patients Before Laryngoscope-Guided Tracheal Intubation

We determined the efficacy of the laryngeal mask airway ProSeal™ (PLMA) as a temporary ventilatory device in morbidly obese patients before laryngoscope-guided tracheal intubation. Sixty patients (body mass index 35–60 kg/m2) scheduled for elective surgery, who preferred airway management under general anesthesia, were studied. The induction of anesthesia was with midazolam/fentanyl/propofol and maintenance was with sevoflurane 1%–3% in oxygen 100%. The PLMA was inserted and an effective airway established. Rocuronium was given IV for paralysis. Oropharyngeal leak pressure, ease of gastric tube placement, residual gastric volume, fiberoptic position of the airway/drainage tube, and ease of ventilation at a tidal volume of 8 mL/kg was determined. The PLMA was then removed and laryngoscope-guided tracheal intubation attempted. The number of insertion/intubation attempts (maximum two each) and time taken to establish an effective airway with each device were recorded. An effective airway was obtained at the first insertion attempt in 90% of patients (54/60) and at the second attempt in 10% (6/60). The time taken to provide an effective airway was 15 ± 7 s (7–42 s). Oropharyngeal leak pressure was 32 ± 8 cm H2O (12–40 cm H2O). The residual gastric volume was 36 ± 46 mL (0–240 mL). Positive pressure ventilation without air leaks was possible in 95% of patients (57/60). The vocal cords were seen from the airway tube in 75% of patients (45/60), but the esophagus was not seen. The fiberoptic view from the drainage tube revealed mucosa in 93% of patients (56/60) and an open upper esophageal sphincter in 7% (4/60). Tracheal intubation was successful at the first attempt in 90% of patients (54/60), at the second attempt in 7% (4/60), and failed in 3% (2/60). In these latter two patients, the PLMA was reinserted and surgery performed uneventfully with the PLMA. The time taken to tracheally intubate the patient was 13 ± 10 s (8–51 s). There were no episodes of hypoxia (Spo2 <90%) or other adverse events. There were no differences in insertion success rate, or the time to successful insertion between the PLMA and laryngoscope-guided intubation. We conclude that the PLMA is an effective temporary ventilatory device in grossly or morbidly obese patients before laryngoscope-guided tracheal intubation.