Downfolding of the epiglottis induced by the laryngeal mask airwayTM in children: a comparison between two insertion techniques

BACKGROUND: The purpose of this study was to compare the incidence of the downfolding of the epiglottis in children during insertion of the laryngeal mask airway (LMATM) using the standard technique and an alternative technique with the cuff partially inflated. METHODS: Eighty paediatric patients were randomized into two groups and were anaesthetized using the LMA inserted with one of the two techniques. RESULTS: There was no difference in the successful rate of insertion, fibreoptic findings and the lowest intraoperative SpO2 between the two groups. CONCLUSIONS: The partially inflated cuff insertion technique does not increase the incidence of the downfolding of the epiglottis in children and would be an acceptable alternative to the standard technique.     

The rotational technique with a partially inflated laryngeal mask airway improves the ease of insertion in children

BACKGROUND: This study compared the ease of insertion of the laryngeal mask airway (LMA) with a partially inflated cuff using the standard 'nonrotational' technique versus the rotational technique. METHODS: One hundred and forty-five children undergoing anaesthesia using the LMA were randomly assigned to either method. The cuff was partially inflated in both groups. The ease of insertion was assessed by the time taken to complete the LMA insertion, the number of attempts before successful placement and the occurrence of complications. RESULTS: The success rate of insertion at the first attempt was higher in the rotational technique group (99% versus 79%, P < 0.05). All patients in the rotational group had the mask inserted within two attempts. On the other hand, three patients had the mask inserted on the first attempt with the rotational technique after three unsuccessful attempts by an anaesthesiologist with the standard 'nonrotational' technique. Insertion technique made no difference on insertion time. CONCLUSIONS: The rotational technique was associated with a higher success rate for insertion and a lower incidence of complications in children. Using the rotational technique with a partially inflated cuff could be the first-choice approach in paediatric patients.     

Influence of cuff volume on oropharyngeal leak pressure and fibreoptic position with the laryngeal mask airway

We studied the size 4 laryngeal mask airway (LMA) to test the hypothesis that oropharyngeal leak pressure and fibreoptic position improves with increasing cuff volume. After LMA insertion, 50 anaesthetized adult patients had the cuff inflated in 5-ml increments to 40 ml. Oropharyngeal leak pressure was optimal at 15 ml and decreased at higher volumes. The fibreoptic position was optimal at 0- 20 ml and deteriorated at higher volumes. Gastric insufflation was detected more frequently when the cuff volume exceeded 20 ml. We conclude that inflation of the size 4 LMA to the maximum recommended volume provides suboptimal conditions and that this value should be reduced from 30 to 20 ml.      

Laryngeal mask airway insertion in children: comparison between rotational, lateral and standard technique

Background:  The purpose of the study was to compare the success and ease of insertion of three techniques of laryngeal mask airway (LMA) insertion; the standard Brain technique, a lateral technique with cuff partially inflated and a rotational technique with cuff partially inflated.
Methods:  One hundred and sixty-eight ASA I and II children aged 6 months to 6 years undergoing short elective surgical procedures lasting 40–60 min were included in the study. A standard anesthesia protocol was followed for all patients. Patients were randomly allocated into one of the three groups i.e. standard (S), rotational (R) and lateral (L). The primary outcome measure of the study was success rate at the first attempt using three techniques of LMA insertion. Secondary outcomes measures studied were overall success rate, time before successful LMA insertion, complications and maneuvers used to relieve airway obstruction.
Results:  Successful insertion at the first attempt was significantly higher in group R (96%) compared with group L (84%) and group S (80%) ( P  =   0.03). Overall success rate (i.e. successful insertion with two attempts) was 100% for group R, 93% for group L and 87% for group S ( P  =   0.03). Time for successful insertion was significantly lower in group R compared with group L and S ( P  <   0.001). The incidence of complications was lower in group R.
Conclusions:  A rotational technique with partially inflated cuff is associated with the highest success rate of insertion and lowest incidence of complications and could be the technique of first choice for LMA insertion in pediatric patients.     

Appropriate size of laryngeal mask airway for children

The aim of this crossover study was to determine the optimal size of laryngeal mask airway in children weighing 10 to 20 kg. In each of 67 apnoeic anaesthetized children, the size 2 and size 2 1/2 laryngeal mask airways were inserted consecutively by a skilled user and the cuff inflated to 60 cmH2O. Each LMA was assessed for the ease of insertion (by the number of attempts), oropharyngeal leak pressure, anatomical position (assessed fibreoptically) and the volume of air required to achieve intracuff pressure of 60 cmH2O. During the measurement of oropharyngeal leak pressure, the airway pressure was not allowed to exceed 30 cmH2O. There was no failed attempt at insertion with any size. The oropharyngeal leak pressure was significantly less for the size 2 LMA compared to the size 2 1/2 LMA (P < 0.001). The oesophagus was visible on three occasions, all with the size 2 LMA. Gastric insufflation occurred in three patients, all with the size 2 LMA. The incidence of low oropharyngeal leak pressure (< 10 cmH2O) was low (9.0%) and all occurred with the size 2 LMA. The fibreoptic bronchoscope scores were not significantly different between the two sizes of LMAs. The volume of air to achieve intracuff pressure of 60 cmH2O was much lower than the maximum recommended volume (5.1 ml for size 2 and 6.2 ml for size 2 1/2). We conclude that the size 2 1/2 LMA provides a better fit than size 2 in children 10 to 20 kg.     

Comparison of laryngeal mask airway (LMA)-Proseal™ and the LMA-Classic™ in ventilated children receiving neuromuscular blockade

PURPOSE: To determine whether a functional difference exists between the size 2 laryngeal mask airway (LMA)-Classic (CLMA) and LMA-Proseal (PLMA) in anesthetized children who have received neuromuscular blockade. Airway leak during intermittent positive pressure ventilation (IPPV) and adequacy of fibreoptic laryngeal view were the primary study outcomes. METHODS: A randomized, controlled, single-blinded study of 51 ASA I or II children weighing 10-20 kg was undertaken. The anesthetic technique was standardized. Following insertion of the LMA and cuff inflation to 60 cm H(2)O, we measured oropharyngeal leak pressure and gastric insufflation and leak fraction during IPPV, and evaluated the adequacy of fibreoptic view. RESULTS: Oropharyngeal leak pressure measured by neck auscultation was higher for the PLMA compared to the CLMA (23.7 vs 16.5 cm H(2)O, P = 0.009) but, when measured by the inspiratory hold maneuver was not significantly different (24.8 vs 20.3 cm H(2)O, respectively, P = 0.217). Leak fraction values were similar for the CLMA and the PLMA (21.2%. vs 13.3%, respectively, P = 0.473). A satisfactory view of the larynx was obtained more frequently in the PLMA group (21/25 vs 10/25, P = 0.003). Gastric insufflation during leak determination was more common with the CLMA (12/26 vs 2/25 CLMA vs PLMA, respectively, P = 0.006). CONCLUSION: In children undergoing IPPV with neuromuscular blockade, the size 2 PLMA is associated with a higher leak pressure by auscultation and less gastric insufflation compared to the CLMA. Leak pressures assessed by manometric stability are similar with these two devices. The improved fibreoptic view of the larynx through the PLMA may be advantageous for bronchoscopy.     

Saline as an alternative to air for filling the laryngeal mask airway cuff

We have assessed a new method to evacuate saline completely from the laryngeal mask airway (LMA) cuff and tested the hypothesis that intracuff pressures, fibreoptic position and oropharyngeal leak pressures are similar for saline compared with air during nitrous oxide- oxygen anaesthesia. Eight size 4 LMA were inflated with saline 30 ml. After syringe evacuation, median residual weight was 0.56 (range 0.24- 0.98) g; after additional manual cuff squeezing it was 0.26 (0.21-0.35) g; and after drying for 12 h at 60 degrees C with the valve open it was -0.02 (-0.05-0.04) g. Pressure-volume curves of four size 3-5 LMA showed that compliance was lower for the saline-filled cuff. A clinical study of 20 patients allocated randomly to have saline or air in the cuff showed a significant increase in intracuff pressure with air, but not saline, during nitrous oxide-oxygen anaesthesia. The fibreoptic position of the LMA changed more frequently in the air, compared with the saline-filled group (four of 10 vs none of 10; P = 0.04). Oropharyngeal leak pressures were similar between groups. We conclude that the saline-inflated LMA cuff was reliably emptied and more stable in terms of intracuff pressures and possibly fibreoptic position. Filling the LMA cuff with saline is a viable option during laser surgery to the airway.      

A comparison of postoperative sore throat after use of laryngeal mask airway and tracheal tube

Purpose We compared the degree of postoperative sore throat (PST) after use of a laryngeal mask airway (LMA; by two insertion techniques) and a tracheal tube (TT) in adult patients.Methods Eighty-six adult patients undergoing surgery of an extremity were randomized into three groups. The LMAs (size 4 for men, 3 for women) and TTs were lubricated with 2% lidocaine gel. After the induction of anesthesia, an LMA with the cuff deflated was inserted and then the cuff was inflated in group A, an LMA with the cuff inflated was inserted in group B, and the trachea was intubated using vecuronium in group C; staff anesthesiologists performed all these methods. LMA cuffs were inflated with the maximum recommended volume of air. TT cuffs were inflated with the minimum volume of air without gas leakage at 20cmH₂O pressure. The mode of ventilation depended on the individual anesthesiologists. Blood traces on the devices were examined after their removal. PST was rated immediately after anesthesia and on the first postoperative day, using a three-point score and a 100-mm visual analog scale, respectively.Results Most of the patients receiving an LMA breathed spontaneously and those receiving a TT underwent controlled ventilation. The ratio of positive blood traces on devices, as well as the degree of PST immediately after anesthesia, was similar in the three groups; however, on the first postoperative day, the severity of PST was greater in the LMA groups than in the TT group (P = 0.016). The severity of PST was similar with the two LMA insertion techniques.Conclusion In the conditions of our study, LMAs inserted with the cuff either fully inflated or deflated worsened PST compared with TTs.This work was presented in part at the 49th annual meeting of the Japanese Society of Anesthesiologists, Fukuoka, Japan, April 18–20, 2002     

A modified technique for insertion of the laryngeal mask airway in children

We modified the technique for laryngeal mask airway (LMA) insertion in children. This modification involves inserting a two-thirds inflated LMA with its lumen facing laterally toward left and then rotating it 90 degrees clockwise as it passes downwards into position behind the larynx. Then the cuff is inflated fully. We conducted a survey on the use of LMA in ten consecutive children for minor superficial surgery. After slow induction, anesthesia was maintained with 3.0% of end-tidal sevoflurane concentration in 100% oxygen for 5 minutes before insertion of LMA. No muscle relaxant was used. Successful insertion was judged by the clinical integrity of the airway. The standard LMA insertion technique or another airway device was applied when three trials had failed. Traumatic insertion was observed by the attachment of blood clots to the surface of the removed LMA. A satisfactory airway was achieved in all of the children who participated in the survey. There were no significant differences in vital signs between pre- and post-insertion. Only one child was found to have attachment of blood clots on the surface of the removed LMA. We conclude that our technique would be one recommended method in pediatric practice.     

A randomised comparison of the self-pressurised air-Q(TM) intubating laryngeal airway with the LMA Unique(TM) in children*

We conducted a randomised trial comparing the self‐pressurised air‐Q^TM intubating laryngeal airway (air‐Q SP) with the LMA‐Unique in 60 children undergoing surgery. Outcomes measured were airway leak pressure, ease and time for insertion, fibreoptic examination, incidence of gastric insufflation and complications. Median (IQR [range]) time to successful device placement was faster with the air‐Q SP (12 (10–15 [5–18])) s than with the LMA‐Unique (14 (12–17 [6–22]) s; p = 0.05). There were no statistically significant differences between the air‐Q SP and LMA‐Unique in initial airway leak pressures (16 (14–18 [10–29]) compared with 18 (15–20 [10–30]) cmH₂O, p = 0.12), an airway leak pressures at 10 min (19 (16–22 [12–30]) compared with 20 (16–22 [10–30]) cmH₂O, p = 0.81); fibreoptic position, incidence of gastric insufflation, or complications. Both devices provided effective ventilation without the need for airway manipulation. The air‐Q SP is an alternative to the LMA‐Unique should the clinician prefer a device not requiring cuff monitoring during anaesthesia.     

Preliminary evaluation of a new prototype laryngeal mask in children

We have assessed a prototype laryngeal mask airway (pLMA) in 50 anaesthetized children for ease of insertion, oropharyngeal leak pressures, gastric insufflation and fibreoptic position. The pLMA has a second smaller mask, which rests against the upper oesophageal sphincter, and a second cuff to increase the seal pressure of the glottic mask. All insertions were graded as easy and an effective airway was achieved in all patients. Oropharyngeal leak pressure was > 40 cm H2O in 49 of 50 patients. Gastric insufflation was not detected by epigastric auscultation. In 46 of 50 patients, the vocal cords were seen via a fibreoptic laryngoscope. One patient regurgitated clear fluid, but aspiration did not occur. On removal, blood staining was detected in three of 50 children. We conclude that the pLMA was easy to insert, facilitated high airway pressure ventilation and may provide some protection against gastric insufflation.      

Laryngeal mask airways – to inflate or to deflate after insertion?

Background: Hyperinflation of the laryngeal mask airway (LMA) cuff is known to be a risk factor for airway morbidity and increased leakage around the LMA. While the manufacturers’ recommendation is to inflate the cuff with the maximum recommended volumes and/or to adjust the cuff pressure to <60 cmH₂O, cuff pressures below 40 cmH₂O have been shown to be associated with a minimal rate of sore throat and minimal leakage. However, it remains to be determined whether inflation or deflation is needed to achieve favorable pressures. Therefore, we assessed the need for cuff‐volume adjustment following insertion of the LMA unchanged straight from the sterile packaging in a prospective audit. Methods: One thousand children (0–16 years) undergoing elective surgery were consecutively included in this quality of care audit. After taking the LMA from its sterile packaging, the LMA cuff was emptied and the amount of air recorded. Then, the same amount of air was returned into the LMA, the LMA was inserted into the patient, and the cuff pressure was measured using a calibrated cuff manometer. Results: Following insertion of the LMA (without further inflation or deflation of the cuff), 20.5% of children had cuff pressures ≥60 cmH₂, while 55.7% had LMA cuff pressures <40 cmH₂O. Cuff pressures were also significantly higher in size 1 LMAs (66.6% had cuff pressures ≥60 cmH₂O and 2% <40 cmH₂O) compared with all other sizes (P < 0.05). Furthermore, cuff pressures in LMAs with a poly vinyl chloride (PVC) surface were higher compared to LMAs with a silicone surface (65.2%≥60 cmH₂O and 9.3% <40 cmH₂O vs 9%≥60 cmH₂O and 67.6% <40 cmH₂O, respectively). Conclusions: This study demonstrates that LMAs, particularly when using small‐sized LMAs or LMAs with a more rigid PVC surface, need to be deflated following insertion of the device rather than inflated to avoid cuff hyperinflation. Hence, cuff pressures should be measured routinely using a manometer to minimize potential pressure‐related airway complications.     

The Laryngeal Mask Airway SupremeTM– a single use laryngeal mask airway with an oesophageal vent. A randomised, cross-over study with the Laryngeal Mask Airway ProSealTM in paralysed, anaesthetised patients

The LMA Supreme^TM is a new extraglottic airway device which brings together features of the LMA ProSeal^TM, Fastrach^TM and Unique^TM. We test the hypothesis that ease of insertion, oropharyngeal leak pressure, fibreoptic position and ease of gastric tube placement differ between the LMA ProSeal^TM and the LMA Supreme^TM in paralysed anesthetised patients. Ninety‐three females aged 19–71 years were studied. Both devices were inserted into each patient in random order. Two attempts were allowed. Digital insertion was used for the first attempt and guided insertion for the second attempt. Oropharyngeal leak pressure and fibreoptic position were determined during cuff inflation from 0 to 40 ml in 10 ml increments. Gastric tube insertion was attempted if there was no gas leak from the drain tube. First attempt and overall insertion success were similar (LMA ProSeal^TM, 92% and 100%; LMA Supreme^TM 95% and 100%). Guided insertion was always successful following failed digital insertion. Oropharyngeal leak pressure was 4–8 ml higher for the LMA ProSeal^TM over the inflation range (p < 0.001). Intracuff pressure was 16–35 cm higher for the LMA ProSeal^TM when the cuff volume was 20–40 ml (p < 0.001). There was an increase in oropharyngeal leak pressure with increasing cuff volume from 10 to 30 ml for both devices, but no change from 0 to 10 ml and 30–40 ml. There were no differences in the fibreoptic position of the airway or drain tube. The first attempt and overall insertion success for the gastric tube was similar (LMA ProSeal^TM 91% and 100%; LMA Supreme^TM 92% and 100%). We conclude that ease of insertion, gastric tube placement and fibreoptic position are similar for the LMA ProSeal^TM and LMA Supreme^TM in paralysed, anaesthetised females, but oropharyngeal leak pressure and intracuff pressure are higher for the LMA ProSeal^TM.     

A randomised trial comparing the i-gel (TM) with the LMA Classic (TM) in children

We performed a prospective, randomised trial comparing the i-gel(TM) with the LMA Classic(TM) in children undergoing general anaesthesia. Ninety-nine healthy patients were randomly assigned to either the i-gel or the LMA Classic. The outcomes measured were airway leak pressure, ease of insertion, time taken for insertion, fibreoptic examination and complications. Median (IQR [range]) time to successful device placement was shorter with the i-gel (17.0 (13.8-20.0 [10.0-20.0]) s) compared with the LMA Classic (21.0 (17.5-25.0 [15.0-70.0]) s, p = 0.002). There was no significant difference in oropharyngeal leak pressure between the two devices. A good fibreoptic view of the glottis was obtained in 74% of the i-gel group and in 43% of the LMA Classic group (p < 0.001). There were no significant complications. In conclusion, the i-gel provided a similar leak pressure, but a shorter insertion time and improved glottic view compared with the LMA Classic in children.     

蛇形喉周通气道和喉罩用于儿科患者的随机前瞻性研究

背景蛇形喉周通气道（CobraPLA）在成人正压通气时,密封压力优于单纯喉罩（LMAU）,本研究旨在比较两者在婴儿和儿童中的使用效果。方法200例小儿患者随机分为CobraPLA组和LMAU组,测量套囊充气压力为40和60cmH2O时气道的密封效果,插入的难易度和时间,手术后咽痛、发声困难、喉痉挛、支气管痉挛和胃内胀气的发生率,间断测量CobraPLA端和麻醉呼吸回路Y型接口处的呼气末二氧化碳浓度（ETCO2）。对主要转归指标,各组又分为小型号和大型号CobraPLA及LMAU亚组进行分析。结果以均数±标准差表示,P〈0．05表示有显著性差异。结果套囊充气压为60cmH2O时,大型号CobraPLA亚组的气道密封压力（22±7cmH2O）明显高于小型号CobraPLA亚组（18±5cmH2O）及大型号LMAU亚组（16±5cmH2O）（P〈0．001）;CobraPLA组比LMAU组更不易移位（手术前和手术后的解剖合适度评分相同）,气体入胃也少;CobraPLA头端ETCO,测量值比Y型接口处高6．4±6mmHg。结论从大多数参数分析来看,CobraPLA与LMAU在儿科患者麻醉中的作用相当,某些方面优于后者。     

Laryngeal mask airway insertion in paediatric anaesthesia: comparison between the reverse and standard techniques.

Sixty-seven children between one and 15 years of age were randomized to have Laryngeal Mask Airway (LMA) insertion using either the standard technique (Group A) as described by Brain or the "reverse technique" (involving a 180 degree turn after insertion with the cuff facing the palate) (Group B). A blinded observer using a fibreoptic bronchoscope assessed the final position of the LMA. The LMA had to be placed within 15 seconds for the procedure to be considered "successful". The success rate using the standard technique was 90.3% (28/31) and 100% (36/36) using the reverse technique (P value 0.06). The 95% confidence interval for the difference in success rates between Group B and A (B-A) was -0.73% to 20.1%. It is our opinion that the reverse technique of insertion of the LMA is an acceptable alternative to the standard technique.     

The new perilaryngeal airway (CobraPLA) is as efficient as the laryngeal mask airway (LMA) but provides better airway sealing pressures

The Laryngeal Mask Airway (LMA) is a frequently used efficient airway device, yet it sometimes seals poorly, thus reducing the efficacy of positive-pressure ventilation. The Perilaryngeal Airway (CobraPLA) is a novel airway device with a larger pharyngeal cuff (when inflated). We tested the hypothesis that the CobraPLA was superior to the LMA with regard to insertion time and airway sealing pressure and comparable to the LMA in airway adequacy and recovery characteristics. After midazolam and fentanyl administration, 81 ASA physical status I-II outpatients having elective surgery were randomized to receive an LMA or CobraPLA. Anesthesia was induced with propofol (2.5 mg/kg IV), and the airway was inserted. We measured 1) insertion time; 2) adequacy of the airway (no leak at 15-cm-H2O peak pressure or tidal volume of 5 mL/kg); 3) airway sealing pressure; 4) number of repositioning attempts; and 5) sealing quality (no leak at tidal volume of 8 mL/kg). At the end of surgery, gastric insufflation, postoperative sore throat, dysphonia, and dysphagia were evaluated. Data were compared with unpaired Student's t-tests, chi2 tests, or Fisher's exact tests; P < 0.05 was significant. Patient characteristics, insertion times, airway adequacy, number of repositioning attempts, and recovery were similar in each group. Airway sealing pressure was significantly greater with CobraPLA (23 +/- 6 cm H2O) than LMA (18 +/- 5 cm H2O, P < 0.001). The CobraPLA has insertion characteristics similar to the LMA but better airway sealing capabilities.     

Use of cuffed oropharyngealvs laryngeal mask airway in elderly patients

PURPOSE: This study was designed to compare the new cuffed oropharyngeal airway (COPA) to the laryngeal mask airway (LMA) in elderly patients. METHODS: In a randomized, controlled study, 80 patients, age > or = 65, ASA I-III, undergoing urology procedures, were managed with either COPA or LMA. Propofol requirements for insertion of the devices, ease of insertion and removal, airway manipulations, mean arterial pressure, heart rate, P(ET)CO2, SpO2, peak inspiratory pressure, selection of the appropriate size of the device and leaks, fibreoptic visualization of larynx and complications were studied. RESULTS: There were more airway manipulations in the COPA group than in the LMA group (40% and 5% respectively) whereas P(ET)CO2 was higher in the LMA group (P < 0.05). In 60% of COPA patients the vocal cords could not be visualized but ventilation was adequate in all but two cases. Postoperative sore throat occurred in 20% of patients with LMA vs 10% with COPA). Bloody secretions on the device were present in two patients managed with LMA. CONCLUSION: In elderly patients COPA required more airway manipulations than the LMA. Laryngeal mask airway caused more sore throats, but was better for fibreoptic visualisation of the larynx. Both are excellent options when intubation is not indicated/desired.     

A randomised comparison of the i‐gel™ and the Laryngeal Mask Airway Classic™ in infants

We performed a randomised comparison of the i‐gel? and the Laryngeal Mask Airway (LMA) Classic? in children aged less than a year who were undergoing general anaesthesia for elective surgery. Fifty‐four infants were randomly allocated to either the i‐gel or the LMA Classic. We measured performance characteristics, fibreoptic views through the device and complications. Success rate at first insertion attempt was 100% (27/27) in the i‐gel group compared with 88% (23/26) in the LMA Classic group. Insertion of the device was considered easy in 26/27 (96%) patients in the i‐gel group compared with 18/26 (69%) patients in the LMA Classic group (p = 0.009). There were no differences between the groups in insertion times, fibreoptic views through the device, airway leak pressures or complications. We conclude that the i‐gel was considered easier to insert than the LMA Classic in infants.     

A randomised comparison of the LMA SupremeTM and LMAProSealTM in children

We conducted a randomised trial comparing the size‐2 LMA Supreme? with the LMA ProSeal? in 60 children undergoing surgery. The outcomes measured were airway leak pressure, ease and time for insertion, fibreoptic examination, incidence of gastric insufflation, ease of gastric tube placement, quality of the airway during anaesthetic maintenance and complications. There were no statistically significant differences between the LMA Supreme and LMA ProSeal in median (IQR [range]) insertion time (12 (10–15 [7–18]) s vs 12 (10–13 [8–25]) s; p = 0.90), airway leak pressures (19 (16–21 [12–30]) cmH₂O vs 18 (16–24 [10–34]) cmH₂O; p = 0.55), fibreoptic position of the airway or drain tube, ease of gastric access and complications. Both devices provided effective ventilation requiring minimal airway manipulation. The LMA Supreme can be a useful alternative to the LMA ProSeal when single‐use supraglottic devices with gastric access capabilities are required.