Mucosal pressures from the cuffed oropharyngeal airway vs the laryngeal mask airway

We tested the hypothesis that pressures exerted on the pharyngeal mucosa by the laryngeal mask airway (LMA) and cuffed oropharyngeal airway (COPA) differ, in 20 male and 20 female adult patients. Microchip pressure sensors were attached to the LMA and COPA at four similar anatomical locations (base of the tongue, lateral pharynx, posterior pharynx and distal oropharynx) and two dissimilar locations (LMA, piriform fossa and hypopharynx; COPA, middle of the tongue and proximal oropharynx). Cuff volume was adjusted until oropharyngeal leak pressure (OLP) was 10 cm H2O and mucosal pressures were recorded. This was repeated at an OLP of 15 cm H2O and at maximal OLP. Overall mucosal pressures were higher for the COPA than the LMA at 10 cm H2O (17 vs 3 cm H2O; P < 0.0001), at 15 cm H2O (21 vs 6 cm H2O; P < 0.0001) and at maximal OLP (26 vs 9 cm H2O; P < 0.0001). Mucosal pressures were always higher for the COPA at the base of the tongue, posterior pharynx and lateral pharynx, but were similar in the distal oropharynx. Maximal OLP was higher for the LMA than the COPA (27 (95% confidence intervals 25- 29) vs 16 (12-19) cm H2O; P < 0.0001). We conclude that pressures acting on the mucosa were higher with the COPA compared with the LMA.      

Use of the cuffed oropharyngeal airway as an alternative to the laryngeal mask airway with positive-pressure ventilation.

BACKGROUND: The cuffed oropharyngeal airway is a modified Guedel-type oral airway with a cuff at its distal end. The objectives of this study were to compare the ability of the cuffed oropharyngeal airway and the laryngeal mask airway to provide positive-pressure ventilation during general anesthesia, and to assess their relative ease of use and ability to reduce total fresh gas flow rates. METHODS: In this prospective, randomized study, a cuffed oropharyngeal airway (n = 25) or a laryngeal mask airway (n = 25) device was inserted after induction of anesthesia intravenously using 2 mg/kg propofol. While anesthesia was maintained with sevoflurane and nitrous oxide, the leak pressure, leak fraction (the fractional difference between the inspired and expired tidal volume), minimum fresh gas flow rate, and need for airway manipulations were determined. The anesthesia provider who inserted the device completed an evaluation form at the end of the 15-min study period. RESULTS: Positive-pressure ventilation was established successfully on the first attempt in 92% of the patients when the cuffed oropharyngeal airway was used and in 88% of the patients when the laryngeal mask airway device was used. However, manipulations of the airway device were necessary more frequently (8 vs. 1 patient; P < 0.05) and the leak pressure was less (22 +/- 6 cm water vs. 26 +/- 5 cm water; P < 0.05) with the cuffed oropharyngeal airway than with the laryngeal mask airway. In addition, the leak fraction (0.19 +/- 0.18 vs. 0.31 +/- 0.22; P < 0.05) and the minimum fresh gas flow rate (1.3 +/- 1.5 vs. 2.4 +/- 2.5; P = 0.12) were less in the laryngeal mask airway group. CONCLUSIONS: Positive-pressure ventilation is possible with the laryngeal mask airway and cuffed oropharyngeal airway devices. Although the cuffed oropharyngeal airway can be inserted easily by inexperienced users with a high first-attempt success rate (> 90%), manipulations of the device may be required to maintain a patent airway. The laryngeal mask airway device allows positive-pressure ventilation at slightly greater peak inspiratory pressures.     

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.     

Supreme喉罩用于高血压病老年患者气道管理的效果

目的 评价Supreme喉罩用于高血压病老年患者气道管理的效果.方法 选择高血压病老年患者40例,年龄65～ 75岁,体重45 ～ 70 kg,BMI＜ 35 kg/m2,ASA分级Ⅱ或Ⅲ级,高血压病程＞1年,采用随机数字表法,将患者随机分为2组(n=20):气管插管组(T组)与Supreme喉罩组(S组).静脉注射芬太尼、丙泊酚、维库溴铵行麻醉诱导,下颌松弛后,S组置入Supreme喉罩,T组置入气管导管,行机械通气.七氟醚,丙泊酚和维库溴铵维持麻醉.于入手术室、置入喉罩/气管导管即刻、1、2、5min、切皮、拔除喉罩/气管导管即刻(T0-6)时记录SP、DP、HR、SpO2;于T0-4,6时采集右颈内静脉血样4ml,测定血浆肾上腺素(AE)、去甲肾上腺素(NE)和多巴胺(DA)浓度;记录插管反应和拔管反应的发生情况、置入时间、置入次数;置入喉罩/气管导管后测定肺顺应性、气道峰压、气道密封压、平台压;记录拔除后咽部不良反应的发生情况.结果 与T组比较,S组SP、HR、插管反应、拔管反应和咽部不良反应的发生率、血浆NE、AE和DA的浓度降低,置入时间缩短(P＜0.05).与T0时比较,S组T2时血浆NE浓度升高,T组T1～46时血浆NE浓度升高,T1～3时血浆AE和DA浓度升高(P＜0.05).结论 Supreme喉罩用于高血压病老年患者气道管理的效果优于气管插管,Supreme喉罩置入和拔除反应小,咽部不良反应少.     

Resistive load of laryngeal mask airway and ProSeal laryngeal mask airway in mechanically ventilated patients

BACKGROUND: The ProSeal Laryngeal Mask Airway (PLMA) ventilation tube is narrower and shorter than the standard Laryngeal Mask Airway (LMA) and is without the vertical bars at the end of the tube. In this randomized, crossover study, PLMA and LMA resistances were compared. METHODS: Respiratory mechanics was calculated in 26 anesthetized, mechanically ventilated patients with both LMA and PLMA. The laryngeal mask positioning was fiberoptically evaluated. Differences in the respiratory mechanics of the LMA and the PLMA were attributed to the differences between the laryngeal masks. RESULTS: In the total study population the airway resistance was 1.5 +/- 2.6 hPa.l-1.s-1 (P = 0.005) higher with the PLMA than with the LMA. During the PLMA use, the peak expiratory flow reduced by 0.02 +/- 0.05 l min-1 (P = 0.046), the expiratory resistance increased by 0.6 +/- 1.3 hPa.l-1.s-1 (P = 0.022), and the time constant of respiratory system lengthened by 0.09 +/- 0.18 s (P = 0.023). These differences doubled when the LMA was better positioned than the PLMA, whereas they disappeared when the PLMA was positioned better than the LMA. CONCLUSIONS: The standard LMA offers a lower resistive load than the PLMA. Moreover, the fitting between the laryngeal masks and the larynx, as fiberoptically evaluated, plays a major role in determining the resistive properties of these devices.     

妇科手术患者Guardian喉罩与Supreme喉罩气道管理效果的比较

目的 比较Guardian喉罩与Supreme喉罩用于妇科手术患者气道管理的效果.方法 择期全麻下行妇科手术患者120例,年龄19～80岁,体重50～70kg,ASA分级Ⅰ或Ⅱ级,随机分为2组:Supreme喉罩组(S组,n=59)和Guardian喉罩组(G组,n=61).麻醉诱导后置入4号喉罩,行机械通气.术中监测BP、HR、SpO2、PETCO2和Ppeak.记录喉罩置人情况、置入时间、纤维支气管镜检查分级、气道密封压、正常通气时(VT 8 ml/kg)的气道压、大潮气量(VT20 ml/kg)通气试验时的气道压和漏气的发生情况、术中口咽部漏气的发生情况、拔除喉罩时不良反应和术后咽喉部不良反应的发生情况、麻醉时间、手术时间、喉罩拔除时间和苏醒时间.结果 两组喉罩置入成功率、置入时间、正常通气时的气道压、大潮气量通气试验时的气道压、拔除喉罩时罩体带血和术后咽喉疼痛、声音嘶哑和吞咽困难的发生率、麻醉时间、手术时间、喉罩拔除时间和苏醒时间差异无统计学意义(P＜0.05).两组患者BP、HR、SpO2、Ppeak和PETCO2均在正常范围内.与S组比较,G组纤维支气管镜检查分级和气道密封压升高,大潮气量通气试验时漏气和术中口咽部漏气的发生率降低(P＜0.01).结论 Guardian喉罩和Supreme喉罩置入简单易行,气道密封效果好,可有效保证通气,对咽喉部的刺激小.Guardian喉罩用于妇科手术患者气道管理的效果更好.     

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     

依托咪酯乳剂用于老年患者喉罩放置

目的探讨老年患者喉罩放置时依托咪酯乳剂的合适剂量。方法行择期喉罩全麻下手术的老年患者(年龄>65岁)75例,随机均分为五组:静注芬太尼1μg/kg后,分别静注依托咪酯乳剂0.2 mg/kg(Ⅰ组)、0.25 mg/kg(Ⅱ组)、0.3 mg/kg(Ⅲ组)、0.35 mg/kg(Ⅳ组)、0.4 mg/kg(Ⅴ组),固定由1名麻醉医师放置喉罩。放置喉罩时,患者出现吞咽、呛咳、屏气、喉痉挛等任何气道反应或肢体运动,均认为喉罩置入阳性反应。结果联合应用芬太尼1μg/kg,依托咪酯的50%有效剂量(ED50)为0.24 mg/kg(95%的可信区间为0.21~0.26 mg/kg),95%有效剂量(ED95)为0.35mg/kg(95%的可信区间为0.31~0.44 mg/kg)。结论依托咪酯乳剂0.35 mg/kg复合芬太尼1μg/kg静脉麻醉诱导用于老年患者喉罩放置,血流动力学稳定,不良反应少见。     

Use of intubating laryngeal mask airway for three patients with difficult intubation

We used intubating laryngeal mask airway (ILM) for three patients with difficult intubation, and tracheal intubation was successfully performed through the ILM in all three cases. Difficult intubation in the first case was caused by direct invasion of malignant lymphoma into the right maxillary sinus leading to restricted mouth opening. Neck stiffness due to invasion of metastatic cancer into the cervical spine in the second case and facial trauma caused by traffic accident in the third case gave rise to the difficult intubation. Insertion of the ILM was successfully performed in all the patients following induction of general anesthesia, and the ventilation through the ILM was possible without any difficulties. Subsequently, all patients were intubated through the ILM successfully. We realized that the ILM is useful and should be prepared on the induction of anesthesia in patients suspected of difficult intubation.     

A randomized study to compare ProSeal laryngeal mask airway with classic laryngeal mask airway in anesthetized patients

BackgroundTo overcome the problem of gastric content regurgitation, a device with drain tube and better airway sealing has been made: the ProSeal laryngeal mask airway (PLMA). We aimed to compare the clinical performance of the classic LMA with the PLMA. Several studies comparing these two devices have been done.Our study was designed to compare ease of insertion, airway sealing pressure, and fiber-optic assessment of positioning in adult patients, and we hopes to prove that PLMA is better to LMA in all these aspects. We hypothesized that PLMA would have a better leak pressure than the CLMA and minimum difference in leak pressure of 20% between them was considered clinically significant.Material and methodsOne hundred adult patients of either sex between age group of 18–65 years scheduled for elective surgery were included in the study. Patients were randomly allocated to two groups of 50 patients each. In group I CLMA and in group II PLMA were used. The number of attempts, ease of insertion, time of insertion, and failure if occurred were noted down. Hemodynamic changes, airway sealing pressure, and the fiber-optic were also recorded.ResultsData thus compiled showed that insertion was successful in first attempt in 94% cases with LMA as well as PLMA. The time taken for successful placement of LMA and - PLMA was 15 and 17 s, respectively. Sealing pressure was higher for group II at all cuff volumes. More number of patients (89%) in group II had a fiber optic score of I and II as compared to group I which had 81% patients with score I and II.ConclusionWe conclude that PLMA is easy to insert with a short insertion time, high success of placement at first attempt, and capable of achieving a more effective seal than LMA.     

Comparative evaluation of the prolonged use of the cuffed oropharyngeal airway and the laryngeal mask airway in spontaneously breathing anaesthetized patients.

The cuffed oropharyngeal airway (COPA) was compared with the laryngeal mask airway (LMA) with respect to airway quality and respiratory adverse events in 140 spontaneously breathing patients undergoing procedures of duration more than 1 h. Patients were allocated randomly to receive either a COPA (n = 72) or a LMA (n = 68) for airway management during anaesthesia induced with propofol and maintained with sevoflurane, nitrous oxide and oxygen. Groups were similar when comparing the first-time successful insertion rates (COPA: 94.5%, LMA: 95.6%), but airway manipulations (head tilt, chin lift, jaw thrust) were reported more frequently in the COPA group, 27.8% vs. LMA, 4.4%; P = 0.0005. During the post-induction apnoeic period, all patients were ventilated manually and although, mean (SD) leak pressure was lower in the COPA group (18 (4) cm H2O vs. LMA, 22 (3) cm H2O; P < 0.0001), the tidal volumes achieved did not differ in both groups: COPA, 9.5 (4) mL kg-1 vs. LMA, 10.5 (4.5) mL kg-1. The incidences of intra-operative coughing, gagging, laryngospasm, oxygen desaturation and hypercarbia were similar in both groups. Although both devices are equivalent with respect to the overall respiratory problems during spontaneous breathing anaesthesia of intermediate or prolonged duration, the LMA was associated with fewer airway quality problems, suggesting that it is more efficacious in securing the airway.