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 vs20 +/- 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 vs53/60; 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 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.     

A multicenter study comparing the ProSeal and Classic 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.     

SLIPA~(TM)喉罩与普通喉罩用于全麻气道管理的比较

目的 比较SLIPA~(TM)喉罩(slieamlined pharynx airway liner,SLIPA~(TM))与普通喉罩(1aryngeal mask airway,LMA)用于全麻短小手术气道管理的性能.方法 选择60例ASA Ⅰ或Ⅱ级择期全麻下短小手术的成年患者,随机分为2组,分别建立SLIPA~(TM)通气道(SLIPA~(TM)组)或LMA通气道(LMA组).从通气道的操作、咽密封性、正压通气的维持以及剐作用等方面对通气道的性能进行评估.结果 SLIPA~(TM)与LMA插入操作的成功率和难易程度差异无统计学意义.SLIPA~(TM)组最大密封压(22±5)cm H_2O与LMA组(24±6)cm H_2O差异无统计学意义(P>0.05).通气道插入后SLIPA~(TM)组1例患者(3.3%)、LMA组6例患者(20%)需进一步调整位置方可行间歇正压通气;术中lJMA组5例患者(16.7%)需重新调整方可维持间歇正压通气,SLIPA~(TM)组均顺利完成手术全程间歇正压通气(P<0.05).2种喉罩通气道喉损伤的发生率差异无统计学意义.结论 SLIPA~(TM)喉罩的临床性能与LMA相似,是一种可替代LMA的通气道.SLIPA~(TM)喉罩操作简便,对咽喉损伤较小,维持间歇正压通气较LMA更为稳定.     

Positive pressure ventilation with the ProSeal versus classic laryngeal mask airway: a randomized, crossover study of healthy female patients

IMPLICATIONS: The ProSeal and classic laryngeal mask airways are equally effective ventilatory devices in healthy female patients at tidal volumes of 8 and 12 mL/kg with the cuff semi- or fully inflated, but leakage of small volumes of air from the mouth occurs more frequently with the laryngeal mask airway.     

Size 2 ProSeal laryngeal mask airway: a randomized, crossover investigation with the standard laryngeal mask airway in paediatric patients

Background. One of the main concerns with the use of the standardlaryngeal mask airway (SLMA) in small infants is that its low-pressureseal might be inadequate for positive pressure ventilation sothat there is a risk of gas leakage into the stomach with thesubsequent risk of regurgitation. The new ProSeal^TM LMA (PLMA)has been shown to form a more effective seal than the SLMA andto facilitate gastric tube placement in adults. The first paediatricsize PLMA became available recently. Methods. Thirty anaesthetized, non-paralysed children aged 46(19) months, weighing 16 (10–21) kg, were studied. TheSLMA and PLMA were inserted in random order into each patient.Airway leak pressure and maximum tidal volume were measured.Ease of insertion, quality of initial airway and fibreopticposition were also determined. Gastric tube placement was assessedfor the PLMA. Results. The airway leak pressure and maximum tidal volume weresignificantly higher for the PLMA (P=0.001). Ease of insertionand quality of initial airway were similar for both devices.Air entry into the stomach occurred more frequently with theSLMA (P=0.005). Gastric tube placement was possible in all patients. Conclusions. The size 2 PLMA offered some advantages over thesame size of SLMA in this crossover investigation. The highreliability of gastric tube placement and the significantlyincreased airway leak pressure might have important implicationsfor use of this device for positive pressure ventilation ininfants.      

食管引流型喉罩间歇正压通气时头前屈位对气道密封压的影响

Objective To evaluate the influence of head anteflexion on airway sealing pressure during intermittent positive pressure ventilation(IPPV) with ProSeal laryngeal mask airway (PLMA) with an esophageal vent.Methods Fifty ASA Ⅰ or Ⅱ patients (20 males and 30 females), aged 18-51 ye are, weighing 50-70 kg and scheduled for elective plastic surgery under general anesthesia, were enrolled in this study. Anesthesia was induced with fentanyl 2 μg/kg, propofol 2 μg/kg and vecuromium 0.1 mg/kg. PLMA with an esophageal vent was inserted at 2 min after intravenous vecuronium injection.The airway sealing pressure, the anatomic position of the cuff and the efficacy of positive pressure ventilation were checked in the neutral and anteflexed head positions with the cuff deflated and inflated to an intracuff pressure of 60 cm H2 O, respectively.Results The lungs were better ventilated in the head anteflexion position than in the head neutral position whether the cuff was deflated or inflated. There was no significant difference in the volume of air required to achieve an intracuff pressure of 60 cm H2O between the two head positions ( P＞ 0.05). The airway seating pressure increased from (27 ± 6) cm H2O in the head neutral position to (33 ± 6) cm H2O in the head anteflexion position, with no significant difference between them ( P＞ 0.05). The expired tidal volume and the peak inspiratory pressure during IPPV were (496 ± 81 ) ml and (14.3 ± 1.9) cm H2O respectively in the head neutral position and (496 ± 81 ) ml and ( 14.5 ± 2.1 )cm H2O respectively in the head anteflexion position.Conclusion Head anteflexion can significantly improve airway sealing but does not affect the anatomic position of the cuff.Appropriate head anteflexion is a simple and effective way to improve IPPV when the airway sealing pressure is inadequate in the head neutral position.     

食管引流型喉罩间歇正压通气时头前屈位对气道密封压的影响

目的 评价食管引流型喉罩(PLMA)间歇正压通气时头前屈位对气道密封压的影响.方法 择期全身麻醉下整形外科手术患者50例,年龄18～51岁,体重50～70 kg,ASA Ⅰ级或Ⅱ级.麻醉诱导后插入PLMA行间歇正压通气.采用自身对照方法,在通气罩未充气和将通气罩内压充气至60 cm H2O时,分别在头正中位和头前屈位对肺通气情况、气道密封压和通气罩的解剖位置进行评价.结果 与头正中位相比,头前屈位气道密封压升高,可改善肺通气情况(P＜0.05),通气罩解剖位置的光导纤维支气管镜分级以及达到恒定通气罩内压60 cm H2O所需的充气量差异无统计学意义(P＞0.05).正压通气的潮气量和吸气峰压在头正中位时分别为(496±81)ml和(14.3±1.9)cm H2O,在前屈位时分别为(496±81)ml和(14.5±2.1)cm H2O,差异无统计学意义(P＞0.05).结论 头前屈位可改善PLMA的气道密闭性但不改变通气罩的解剖位置.当头正中位时气道密封压不能满足实施间歇正压通气时,适度前屈患者头部是改善经PLMA通气效果的简单有效的方法.     

Pressure support ventilation versus continuous positive airway pressure ventilation with the ProSeal laryngeal mask airway: a randomized crossover study of anesthetized pediatric patients

Continuous positive airway pressure (CPAP) and pressure support ventilation (PSV) improve gas exchange in adults, but there are little published data regarding children. We compared the efficacy of PSV with CPAP in anesthetized children managed with the ProSeal laryngeal mask airway. Patients were randomized into two equal-sized crossover groups and data were collected before surgery. In Group 1, patients underwent CPAP, PSV, and CPAP in sequence. In Group 2, patients underwent PSV, CPAP, and PSV in sequence. PSV comprised positive end-expiratory pressure set at 3 cm H(2)O and inspiratory pressure support set at 10 cm H(2)O above positive end-expiratory pressure. CPAP was set at 3 cm H(2)O. Each ventilatory mode was maintained for 5 min. The following data were recorded at each ventilatory mode: ETco(2), Spo(2), expired tidal volume, peak airway pressure, work of breathing patient (WOB), delta esophageal pressure, pressure time product, respiratory drive, inspiratory time fraction, respiratory rate, noninvasive mean arterial blood pressure, and heart rate. In Group 1, measurements for CPAP were similar before and after PSV. In Group 2, measurements for PSV were similar before and after CPAP. When compared with CPAP, PSV had lower ETco(2) (46 +/- 6 versus 52 +/- 7 mm Hg; P < 0.001), slower respiratory rate (24 +/- 6 versus 30 +/- 6 min(-1); P < 0.001), lower WOB (0.54 +/- 0.54 versus 0.95 +/- 0.72 JL(-1); P < 0.05), lower pressure time product (94 +/- 88 versus 150 +/- 90 cm H(2)O s(-1)min(-1); P < 0.001), lower delta esophageal pressure (10.6 +/- 7.4 versus 14.1 +/- 8.9 cm H(2)O; P < 0.05), lower inspiratory time fraction (29% +/- 3% versus 34% +/- 5%; P < 0.001), and higher expired tidal volume (179 +/- 50 versus 129 +/- 44 mL; P < 0.001). There were no differences in Spo(2), respiratory drive, mean arterial blood pressure, and heart rate. We conclude that PSV improves gas exchange and reduces WOB during ProSeal laryngeal mask airway anesthesia compared with CPAP in ASA physical status I children aged 1-7 yr.     

A comparison of the laryngeal mask airway ProSeal and the laryngeal tube airway in paralyzed anesthetized adult patients undergoing pressure-controlled ventilation

We compared the laryngeal mask airway ProSeal (PLMA) and the laryngeal tube airway (LTA), two new extraglottic airway devices, with respect to: 1) insertion success rates and times, 2) efficacy of seal, 3) ventilatory variables during pressure-controlled ventilation, 4) tidal volume in different head/neck positions, and 5) airway interventional requirements. One-hundred-twenty paralyzed anesthetized ASA physical status I and II adult patients were randomly allocated to the PLMA or LTA for airway management. A standardized anesthesia protocol was followed by two anesthesiologists experienced with both devices. The criteria for an effective airway included a minimal expired tidal volume of 6 mL/kg during pressure-controlled ventilation at 17 cm H(2)O with no oropharyngeal leak or gastric insufflation. First attempt success rates at achieving an effective airway were similar (PLMA: 85%; LTA: 87%), but after 3 attempts, success was more frequent for the PLMA (100% versus 92%, P = 0.02). Effective airway time was similar. Oropharyngeal leak pressure was larger for PLMA at 50% maximal recommended cuff volume (29 +/- 7 versus 21 +/- 6 cm H(2)O, P < 0.0001), but was similar at the maximal recommended cuff volume (33 +/- 7 versus 31 +/- 8 cm H(2)O). Tidal volumes (614 +/- 173 versus 456 +/- 207 mL, P < 0.0001) were larger and ETCO(2) (33 +/- 9 versus 40 +/- 11 mm Hg, P = 0.0001) lower for the PLMA. The number of airway interventions was significantly less frequent for the PLMA. Airway obstruction was more common with the LTA. When comparing mean tidal volumes in different head/neck positions, the quality of airway was unchanged in 56 of 60 patients (93%) with the PLMA and 42 of 55 (76%) with the LTA (P = 0.01). The PLMA offers advantages over the LTA in most technical aspects of airway management in paralyzed patients undergoing pressure-controlled ventilation. IMPLICATIONS: The laryngeal mask airway ProSeal offers advantages over the laryngeal tube airway in most technical aspects of airway management in paralyzed patients undergoing pressure-controlled ventilation.     

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.     

Sex-based ProSeal laryngeal mask airway size selection: a randomized crossover study of anesthetized,paralyzed male and female adult patients

We compared the Size 4 and 5 ProSeal laryngeal mask airway (PLMA) in men and the Size 3 and 4, and 4 and 5 PLMA in women in terms of 1) ease of insertion, 2) oropharyngeal leak pressure (OLP), 3) ease of ventilation at a tidal volume of 10 mL/kg, 4) gas exchange, 5) location of gas leak, 6) anatomic position of the airway and drain tube, and 7) mucosal injury. Thirty male and 60 female (ASA physical status I-II; 18-80 yr old) anesthetized, paralyzed patients were studied in a crossover fashion in three equal-sized groups. PLMA insertion was performed by a single experienced operator by using digital manipulation. In male patients comparing the Size 4 and 5, OLP was higher (P = 0.0002) and leak fraction lower (P = 0.03) for the Size 5, but the number of insertion attempts, insertion time, mucosal injury, anatomic position, gas exchange, and location of gas leak were similar. In female patients comparing the Size 4 and 5 PLMA, OLP was higher for the Size 5 (P < 0.0001), but the number of insertion attempts was fewer (P = 0.02), insertion time was quicker (P = 0.02), and there was less mucosal injury (P = 0.01) with the Size 4. There were no differences in anatomic position, gas exchange, or location of gas leak. In female patients comparing the Size 3 and 4 PLMA, OLP was higher (P = 0.0005) and leak fraction was lower (P = 0.03) for the Size 4, but the number of insertion attempts, insertion time, mucosal injury, anatomic position, gas exchange, and location of gas leak were similar. There were no episodes of failed oxygenation, failed ventilation, or gastric insufflation. We conclude that if size is selected by sex, the Size 4 PLMA is preferable for women and the Size 5 PLMA for men. IMPLICATIONS: When sex is used to select the appropriate size of the ProSeal laryngeal mask airway, the Size 4 ProSeal is preferable for women and the Size 5 ProSeal for men.     

食管引流型与标准型喉罩通气道在全身麻醉患者的应用

目的比较食管引流型喉罩通气道(PLMA)和标准型喉罩通气道(SLMA)在全身麻醉患者的应用。方法ASAⅠ~Ⅱ级择期整形外科手术患者60例,随机均分为PLMA组和SLMA组,常规麻醉诱导后,分别插入PLMA或SLMA,并将通气罩充气至60cmH2O。评价两种喉罩通气道的插入特征、气道密封压和漏气部位,记录麻醉诱导前后、喉罩插入时和喉罩插入后5min内SBP、DBP和HR的变化情况。记录麻醉期间发生的呼吸并发症和呼吸道损伤情况。结果PLMA组首次插入即获得满意肺通气的例数高于SLMA组,但PLMA组操作时间明显长于SLMA组(P<0·05)。PLMA组通气罩充气量和气道密封压明显高于SLMA组(P<0·05)。两组插入操作所致的血液动力学反应相似,而且均非常轻微。结论与SLMA相比,PLMA可达到更好的气道密封性,并可提供良好的胃管插入通路,是全身麻醉患者安全有效的呼吸道管理工具之一。     

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     

A randomized crossover comparison of the size 2 1/2 laryngeal mask airway ProSeal versus laryngeal mask airway-Classic in pediatric patients

The laryngeal mask airway (LMA)-ProSeal (P-LMA) forms a more effective seal than the LMA-Classic (C-LMA) and facilitates gastric tube (g-tube) placement in adults. The first pediatric sizes of P-LMA recently became available. In 30 anesthetized, nonparalyzed children, aged 7.7 +/- 2 yr and weighing 27 (20-35) kg, we inserted the size (1/2) P-LMA and C-LMA in random order. Ease of insertion, quality of initial airway, fiberoptic position, airway leak pressure, and maximum tidal volume were determined. G-tube placement was assessed for the P-LMA. Ease of insertion was similar for both devices. The quality of the initial airway was better for the P-LMA (P = 0.01). Airway leak pressure in neutral head position (22.6 versus 18.5 mbar; P = 0.003), maximum flexion (37 versus 26.3 mbar; P < 0.001), maximum extension (15.2 versus 13 mbar; P = 0.045), and maximum tidal volume (1088 versus 949 mL; P = 0.002) were significantly better for the P-LMA. Air entry into the stomach occurred with the C-LMA but not with the P-LMA (P = 0.014). G-tube placement was possible in all patients. The reliability of g-tube placement and the significantly increased airway leak pressure found in this investigation might have important implications for use of the size (1/2) P-LMA for positive pressure ventilation in children.     

A comparison of the ProSeal laryngeal mask and the laryngeal tube in spontaneously breathing anesthetized patients

In this multicenter, randomized study, we compared ease of insertion, postinsertion hemodynamic repercussion, quality of ventilation, and the capacity to achieve a "hands-free" anesthesia delivery between two new devices: the ProSeal laryngeal mask airway (PLMA) and the Laryngeal Tube (LT). The incidence of postoperative laryngopharyngeal discomfort was examined after short surgical interventions in spontaneously breathing patients. After induction with fentanyl and propofol, the respective airways were inserted into 70 adult ASA physical status I and II patients (35 patients in each group). First-attempt insertion success rates were more frequent for the PLMA (77% versus 51%; P < 0.05), but success rates were similar (100% versus 97%) after 3 attempts. The anesthesiologists considered that insertion of the PLMA was easier (P < 0.001). Expired tidal volume was larger with the PLMA (404.9 versus 328.4 mL; P < 0.005) and the ability to achieve hands-free ventilation was more frequent with the PLMA (32 versus 21 cases; P < 0.004). Positional maneuvers with the LT to correct ventilation deficiencies were not always completely effective (5 of 13). There were no differences in the incidence of intolerance, sore throat, dysphagia, and/or dysphonia between the two devices. We conclude that the PLMA showed greater ease of insertion and reliability than the LT for use in nonparalyzed anesthetized patients.     

Pressure-controlled ventilation is superior to volume-controlled ventilation with a laryngeal mask airway in children

Background:  This prospective, randomized, crossover study had two purposes: first, to determine whether pressure-controlled ventilation (PCV) is safer than volume-controlled ventilation (VCV) by preventing gastric insufflation in children ventilated through an laryngeal mask airway (LMA); second, to assess whether the measurement of LMA leak pressure (P_leak) is useful for preventing leakage during positive pressure ventilation (PPV).
Methods:  Forty-one, 2 to 15-year-old children underwent general anesthesia with an LMA. The expiratory valve was set at 30 cmH₂O and P_leak was measured using constant gas flow. Children were randomly ventilated using PCV or VCV for 5 min in order to reach a P_ETCO₂ not exceeding 45 mm Hg, and then they were ventilated with the alternative mode. If the target P_ETCO₂ could not be obtained in one mode, we switched to the other. If both modes failed, children were intubated. Tidal volumes, P_ETCO₂ and airway pressures were noted and compared between modes. Gastric insufflation was checked by epigastric auscultation.
Results:  PCV provided more efficient ventilation than VCV, as targeted P_ETCO₂ was obtained without gastric insufflation using PCV in all cases except one, whereas VCV failed in three cases. No gastric insufflation occurred when ventilating below peak.
Conclusions:  These findings suggest that in the age group studied, PCV is more efficient than VCV for controlled ventilation with a laryngeal mask. Gastric insufflation did not occur with this mode.     

The laryngeal mask airway Unique versus the Soft Seal laryngeal mask: a randomized, crossover study in paralyzed, anesthetized patients

We tested the hypothesis that ease of insertion, oropharyngeal leak pressure, fiberoptic position, ease of ventilation, and mucosal trauma are different for the Soft Seal laryngeal mask airway (SSLM) and the laryngeal mask airway Unique (LMA-U). Ninety paralyzed, anesthetized adult patients (ASA I-II; 18-80 yr old) were studied. Both devices were inserted into each patient in random order. Oropharyngeal leak pressure and fiberoptic position were determined during cuff inflation from 0-40 mL in 10-mL increments and at an intracuff pressure of 60 cm H(2)O. Ease of ventilation was determined by controlling ventilation for 10 min at 8 and 12-mL/kg tidal volume and recording hemoglobin oxygen saturation, end-tidal CO(2), leak fraction, peak airway pressure, and the presence or absence of gastric insufflation. Mucosal trauma was determined by examining the first randomized device for the presence of visible and occult blood. Insertion time was shorter (P = 0.0001) and fewer attempts were required (P = 0.005) for the LMA-U. There were no failed uses of either device. Oropharyngeal leak pressures were similar, but fiberoptic position was superior with the LMA-U (P < or = 0.0003). There were no differences in hemoglobin oxygen saturation, end-tidal CO(2), leak fraction, or peak airway pressure at either tidal volume. Gastric insufflation was not detected in either group at either tidal volume. The frequency of visible (P = 0.009) and occult blood (P = 0.0001) was less with the LMA-U. We conclude that the LMA-U is superior to the SSLM in terms of ease of insertion, fiberoptic position, and mucosal trauma, but similar in terms of oropharyngeal leak pressure and ease of ventilation.