The ProSeal has a shorter life-span than the Classic laryngeal mask airway

We tested the hypothesis that the life-span of the ProSeal laryngeal mask airway (LMA) is shorter than the Classic LMA. We also compared residual cuff volumes and changes in elastance and permeability with use. Six new size 4 ProSeal LMAs and 6 new size 4 Classic LMAs were tested. Each LMA underwent a simulated clinical use cycle until it failed the pre-use check tests. The simulated clinical use cycle comprised: i) inflating the cuff to the maximum recommended volume for 1 h; ii) immersion in an enzymatic solution for 3 min; iii) washing the external and internal surfaces; iv) automatic washing for 14 min (< or =85 degrees C); v) drying for 30 min (< or =75 degrees C); and vi) autoclaving at 134 degrees C for 4 min at 206 kPa. Before the first cycle and every 10 subsequent cycles, the cuff was inflated with 40 mL air and the intracuff pressure was measured immediately and 3 h later. The initial intracuff pressure was taken to be an inverse measure of the elastance or resistance to deformation, and the intracuff pressure change were taken as a measure of the permeability. The residual cuff volume was determined for 10 Classic and 10 ProSeal size 4 LMAs using a gas dilution technique. The mean +/- sd (range) longevity for the ProSeal LMA and Classic LMA was 82 +/- 23 (45-109) uses and 133 +/- 35 (76-176) uses, respectively. The ProSeal LMA has a shorter life-span than the Classic LMA (P = 0.01). For the ProSeal LMA, there was no change in elastance or permeability with use. For the Classic LMA, there was a decrease in elastance (P < 0.0001) and an increase in permeability (P < 0.0001) with use. The residual cuff volume was higher for the ProSeal LMA (2.6 +/- 1.3 mL versus 1.5 +/- 0.9, P = 0.04). We conclude that the life-span of the ProSeal LMA is shorter than the Classic LMA, but both exceed the manufacturer's recommendations of 40 uses. We recommend that reusable LMA devices be discarded when they fail the pre-use check tests, rather than after a specific number of uses.     

Depth of insertion of the ProSeal laryngeal mask airway

Background. The depth of insertion of the ProSeal^TM laryngealmask airway (PLMA     

The ProSeal laryngeal mask airway in children

BACKGROUND: The ProSeal (PLMA) is a new laryngeal mask device with a modified cuff to improve the seal and a drain tube to provide access to the gastrointestinal tract. We assessed the performance of the size 2 (which has no dorsal cuff) and size 3 (which has a dorsal cuff) in terms of insertion success, efficacy of seal, tidal volume, gas exchange, fiberoptic position, gastric tube placement and frequency of problems. METHODS: Eighty children undergoing minor surgery were studied (n = 40, size 2 PLMA, weight 10-25 kg; n = 40, size 3 PLMA, weight >25-50 kg). Induction was with remifentanil and propofol. Insertion was with the introducer tool and by experienced users. Maintenance was with propofol or sevoflurane and pressure controlled ventilation. RESULTS: The first-time and overall insertion success rate was 84 and 100%, respectively. Oropharyngeal leak pressure was 31 +/- 5 cmH2O. There were no gastric or drain tube air leaks. Tidal volume and gas exchange was adequate in all patients, other than two brief episodes of hypoxia because of airway reflex activation. The vocal cords and epiglottis were visible in 99 and 80%, respectively, via the airway tube. The first-time and overall insertion success rate for gastric tube insertion was 87 and 100%, respectively. During maintenance, the PLMA was removed in one patient with airway reflex activation and another required epinephrine for bronchospasm. There were no differences in performance between the sizes 2 and 3 PLMA. CONCLUSION: The PLMA is an effective airway device in children and isolates the glottis from the esophagus when correctly positioned. Despite the lack of a dorsal cuff, the performance of the size 2 was similar to the size 3 PLMA in the age groups tested.     

Suction catheter guided insertion of the ProSeal™ laryngeal mask airway is superior to the digital technique

PURPOSE: We tested the hypothesis that digital insertion of the ProSeal laryngeal mask airway (ProSeal LMA) is more successful when using a suction catheter (SC) as a guide. METHODS: Two hundred and forty-three patients (ASA physical status I-III; aged 18-84 yr) were randomly allocated for the digital or SC-guided technique. The digital technique was performed according to the manufacturer's instructions. The SC technique involved priming the drain tube with the SC so that it protruded by 15 cm, blindly inserting the SC into the pharynx to a depth of 15 cm, followed by the digital technique. Failed insertion was defined by any of the following criteria: 1) failed passage into the pharynx; 2) malposition; and 3) ineffective ventilation. Any airway trauma, and visible or occult blood was noted. Sore throat, dysphonia and dysphagia were assessed 16 to 24 hr postoperatively. RESULTS: Fewer insertion attempts were required with the SC-guided technique (P = 0.02), but first attempt and overall success were similar. The time taken to provide an effective airway was shorter for the SC-guided technique (36 +/- 24 sec vs 44 +/- 28 sec, P = 0.02). A lateral approach was required less frequently with the SC-guided technique (0% vs 4%, P = 0.0004). There were no adverse events. Mouth trauma was more frequent with the digital technique (P = 0.04), but overall trauma was similar. There were no differences in the frequency of visible or occult blood. There were no differences in postoperative airway morbidity. CONCLUSIONS: The SC-guided technique is more frequently successful than the digital technique and is associated with less mouth trauma during insertion of the ProSeal LMA. We suggest that the SC technique may be a useful alternative when the digital technique fails.     

Gum-elastic bougie-guided insertion of the ProSeal laryngeal mask airway: a new technique

We determined the success rates, cardiovascular responses and airway morbidity for gum-elastic bougie-guided insertion of the ProSeal laryngeal mask airway. One hundred anaesthetized, non-paralyzed adults (ASA 1-2 aged 18 to 80 years) were studied. The ProSeal LMA drainage tube was primed with a well-lubricated 16 French gauge gum-elastic bougie with the curved end proximal and the straight end protruding 30 cm beyond the drainage tube tip. The straight end of the gum-elastic bougie was inserted into the oesophagus under laryngoscopic guidance, the laryngoscope removed and the ProSeal LMA inserted using the standard insertion technique and the gum-elastic bougie as a guide. The following variables were recorded: ease of insertion, oropharyngeal leak pressure, ventilatory capability, ease of gastric tube insertion, blood staining on the bougie or LMA at removal, and postoperative airway morbidity. Haemodynamic data were recorded immediately pre-insertion and every minute for five minutes after insertion. Gum-elastic bougie and ProSeal LMA insertion was successful at the first attempt in all patients within 50 seconds. There were no significant increases in heart rate or blood pressure. Oropharyngeal leak pressure was 33 (17-40) cmH2O and ventilation was possible without leak in all patients at 9.5 ml x kg(-1) tidal volume. There were no drainage tube or gastric air leaks. Gastric tube insertion was successful at the first attempt in all patients. Blood staining at removal was not detected on the gum-elastic bougie, but was detected in 3% of ProSeal LMAs. The incidence of sore throat, dysphagia and dysarthria was 21%, 9% and 1% respectively. We conclude that gum-elastic bougie-guided insertion of the ProSeal LMA has a high success rate and is associated with minimal haemodynamic change and a low incidence of trauma.     

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.     

妇科全麻手术患者置入食管引流型喉罩时异丙酚半数有效血浆靶浓度

目的 确定妇科全麻手术患者置入食管引流型喉罩(PLMA)时异丙酚半数有效血浆靶浓度(Cp50).方法 择期行妇科腹腔镜手术患者23例,ASA Ⅰ或Ⅱ级,年龄20～50岁.靶控输注异丙酚行麻醉诱导,初始血浆靶浓度为4 μg/ml,待效应室浓度与血浆靶浓度相等时,置入喉罩.喉罩置入成功的标准为Muzi评分≤2分,喉罩置入后3 min内平均动脉压升高及心率加快不超过基础值的20%.按序贯法确定异丙酚血浆靶浓度,若前一例患者PLMA置人成功,则后一例患者的血浆靶浓度降低0.5 μg/ml;若前一例患者PLMA置入失败,则后一例患者的血浆靶浓度增加0.5 μg/ml.计算异丙酚Cp50及其95%可信区间.结果 PLMA置入成功时异丙酚Cp50为4.6 μg/ml,95%可信区间为4.0～6.2 μg/ml.结论 妇科全麻手术患者(20～50岁)置入PLMA时异丙酚Cp50为4.6 μg/ml.     

Comparison of the standard laryngeal mask airway and the ProSeal laryngeal mask airway in obese patients

Background. The ProSeal^TM laryngeal mask airway (PLMA) may haveadvantages over the laryngeal mask airway (LMA