小儿食管引流型喉罩与经典喉罩插入时适宜呼气末七氟醚浓度的比较

目的比较小儿食管引流型喉罩(PLMA)与经典喉罩(CLMA)插入所需的七氟醚最低肺泡有效浓度(MAC)。方法择期全麻手术患儿54例,年龄3~9岁,ASAⅠ或Ⅱ级,随机均分为PLMA组(P组)和CLMA组(C组)。患儿吸入七氟醚行麻醉诱导,待呼气末七氟醚浓度(CETSev)达到预设值并稳定10 min后插入喉罩。七氟醚的预设值根据Dixon序贯法确定,P、C组首例患儿初始CETSev分别设为2.2%和2.0%,浓度梯度为0.2%。结果患儿插入PLMA和CLMA所需的七氟醚MAC分别为(2.21±0.11)%和(1.99±0.11)%(P<0.01),P、C组CETSev的EC95分别为2.40%(95%CI 2.28%~2.74%)和2.14%(95%CI 2.03%~2.44%)。结论 3~9岁小儿PLMA插入条件满意所需的七氟醚MAC较插入CLMA高。     

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.     

Comparison of laryngeal tube with laryngeal mask airway in anaesthetized and paralysed patients

BACKGROUND AND OBJECTIVE: The laryngeal mask has become a widely accepted alternative to endotracheal intubation and mask ventilation. The laryngeal tube is a relatively new supraglottic airway device for airway management. We compared the new version of the laryngeal tube with the laryngeal mask. METHODS: In a randomized design, either a laryngeal tube (n = 66) or a laryngeal mask (n = 66) were inserted. Ease of insertion, oxygenation and ventilation, spirometry data and postoperative airway morbidity were determined. RESULTS: After successful insertion, it was possible to maintain oxygenation and ventilation in all the patients. Insertion success rates after the first, second and third attempts were 84.8% (n = 56), 12.1% (n = 8) and 3% (n = 2) for the laryngeal tube compared with 56.1% (n = 37), 25.8% (n = 17) and 18.2% (n = 12) for the laryngeal mask (P = 0.001). There was no significant difference in peak airway pressure, and dynamic compliance between the groups (P > 0.05). Blood on the cuff after removal of the device was noted in one patient with the laryngeal tube and in 10 patients with the laryngeal mask. Six patients in the laryngeal mask group complained of hoarseness (P = 0.012).CONCLUSION: With respect to clinical function, the new version of the laryngeal tube and the laryngeal mask are similar and either device can be used to establish a safe and effective airway in paralysed patients.     

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.      

The proseal laryngeal mask airway in prone patients: a retrospective audit of 245 patients

The use of the classic laryngeal mask airway (classic LMA) in the prone position is controversial, but the ProSeal laryngeal mask airway (ProSeal LMA) may be more suitable as it forms a better seal and provides access to the stomach. In the following retrospective audit, we describe our experience with the insertion of and maintenance of anaesthesia with, the ProSeal LMA in 245 healthy adults in the prone position by experienced users. The technique involved (1) the patient adopting the prone position with the head to the side and the table tilted laterally; (2) pre-oxygenation to end-tidal oxygen >90%; (3) induction of anaesthesia with midazolam/alfentanil/propofol; (4) facemask ventilation (5) a single attempt at digital insertion and if unsuccessful a single attempt at laryngoscope-guided, gum elastic bougie-guided insertion; (6) gastric tube insertion; (7) maintenance of anaesthesia with sevoflurane/O/N2O; (8) volume controlled ventilation at 8-12 ml/kg; (9) emergence from anaesthesia in the supine position; and (10) removal ofthe ProSeal LMA when awake. Facemask ventilation was always successful. ProSealLMA insertion was successful in all patients: 237 with digital insertion and eight with bougie-guided insertion. Ventilation was successful in all patients. Gastric tube insertion was successful in all patients. Correctable partial airway obstruction occurred in three patients, but there was no hypoxia, hypercapnoea, displacement, regurgitation, gastric insufflation or airway reflex activation. Our findings suggest that the insertion of and maintenance of anaesthesia with the ProSeal LMA is feasible in the prone position by experienced users.     

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.     

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.     

A randomised crossover trial comparing the i‐gel supraglottic airway and classic laryngeal mask airway*

In a randomised cross‐over study, we compared the performance of the single use i‐gel supraglottic airway and reusable classic laryngeal mask airway (cLMA^TM) in 50 healthy anaesthetised patients who were breathing spontaneously. Primary outcome was successful insertion at first attempt. Secondary outcomes included overall insertion success rate, ease of insertion, leak pressure and fibreoptic position. Success rate for insertion at the first attempt was significantly different (54% with i‐gel vs 86% with cLMA; p = 0.001). Overall success after two attempts (when the anaesthetist was allowed to change the size of the device) improved to 84% with i‐gel vs 92% with cLMA; p = 0.22. In 14 patients, the i‐gel when used first needed to be replaced with a larger size. Leak pressure was higher for the i‐gel (median [IQR] 20 [14–24] cm H₂O than the cLMA 17 [12–22] cm H₂O; p = 0.023). The fibreoptic view through the device was significantly better with the i‐gel than the cLMA, which was statistically significant (p = 0.03). We conclude that, with its current sizing recommendations, the i‐gel is not an acceptable alternative to cLMA. However because of the significantly improved success rate after a larger sized i‐gel was used, we recommend the manufacturer to review the sizing guidelines to improve the success rate.     

Alfentanil dosage when inserting the classic laryngeal mask airway

BACKGROUND: The purpose of this study was to determine an optimum dose of alfentanil, coadministered with 2.5 mg/kg propofol, when inserting a classic laryngeal mask airway. METHODS: Seventy-five adult ethnic Chinese patients with an American Society of Anesthesiologists physiologic status classification I or II and requiring anesthesia for minor surgery with a laryngeal mask were recruited. They were randomly assigned to five dosage groups: placebo or 5, 10, 15, or 20 microg/kg. The study drug plus propofol were administered, and 90 s later, insertion conditions were assessed using a six-category score. The duration of apnea was recorded. A probit analysis was performed and used to estimate the ED50 and ED95 with 95% confidence intervals for each assessment. RESULTS: Twenty-five male and 50 female patients, aged 18-59 yr, were studied. The five groups were similar. Laryngeal mask insertion was successful in all but one alfentanil patient. Duration of apnea increased with increasing dosage of alfentanil to over 5 min (P < 0.001). Dose-responses could not be predicted for categories of resistance to mouth opening and to insertion. For the other four categories, swallowing, gagging, movement, and laryngospasm, ED50 and ED95 with confidence intervals for alfentanil could be determined. CONCLUSION: The optimum dose for alfentanil, when coadministered with 2.5 mg/kg propofol, was 10 microg/kg.     

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.     

Experience with the proseal laryngeal mask in ventriculoperitoneal shunting

ObjectiveTo describe the use, utility, safety, and effectiveness of the Proseal laryngeal mask for airway management in patients undergoing ventriculoperitoneal shunting.Patients and methodsWe retrospectively reviewed the records of all patients in whom the Proseal laryngeal mask was used during ventriculoperitoneal shunting between January 2006 and October 2009. Patient demographic characteristics, airway assessments, type of anesthesia, quality of ventilation, and perioperative complications were recorded.ResultsOf the 43 patients included, 8 (18.6%) had at least 1 difficult airway criterion. We were able to insert the Proseal laryngeal mask in all patients. Ventilation was optimal in 39 (91%) patients, with maintenance of end-expiratory carbon dioxide pressures between 35 and 40 mm Hg and airway pressures above 25 cm H₂O throughout the procedures. Air leaks developed in 3 cases (7%) when the patient was placed in a lateral-cervical position for surgery; these patients required orotracheal intubation before surgery could begin. Mean duration of surgery was 53 minutes. Awakening occurred without incident in all cases.ConclusionsThe Proseal laryngeal mask is useful for airway management in patients undergoing ventriculoperitoneal shunting. Due to the forced position of the neck, however, it may be necessary to reposition the mask or even proceed to orotracheal intubation in some cases. As is the case for other advanced uses, experience with the device is necessary. Material for managing a difficult airway should be on hand.     

A comparison of the proseal laryngeal mask airway, the laryngeal tube S and the oesophageal-tracheal combitube during routine surgical procedures

BACKGROUND AND OBJECTIVE: This study was performed to compare three supraglottic airway devices: the ProSeal laryngeal mask airway (PLMA), the laryngeal tube S (LTS) and the oesophageal-tracheal combitube (OTC) during routine surgical procedures. METHODS: Ninety American Society of Anesthesiologists (ASA) I-III patients scheduled for routine minor obstetric surgery were randomly allocated to the PLMA (n = 30), the LTS (n = 30) or the OTC (n = 30) group, respectively. The overall success rate, insertion time, cuff pressures and resulting airway leak pressures were determined as well as a subjective assessment of handling and the incidence of sore throat, dysphagia and hoarseness were performed. RESULTS: Insertion time until the first adequate ventilation was significantly (P < 0.0001) shorter in the PLMA (median 29 s; 25-75th percentile 25-48 s; range 10-161 s; success rate 100%) and in the LTS group (38 s; 30-44 s; 13-180 s; 100%) compared to the OTC group (75 s; 48-98 s; 35-180 s; 90%). In vivo cuff pressures and airway leak pressures increased with the inflating cuff volume in all devices and were highest in the OTC group. Postoperatively, patients in the PLMA and the LTS group complained significantly less about sore throat (P < 0.001 and 0.05) and dysphagia (P < 0.001 and 0.02) compared to the OTC group, while there was no difference regarding the incidence of hoarseness. Subjective assessment of handling was comparable with the PLMA and the LTS, but inferior with the OTC. CONCLUSIONS: In conclusion, both PLMA and LTS proved to be suitable for routine surgical procedures and proved to be superior to the OTC which cannot be recommended for routine use.     

Randomised crossover comparison of the Ambu AuraOnce Laryngeal Mask with the LMA Classic laryngeal mask airway in paralysed anaesthetised patients

We compared the performance of the Ambu AuraOnce Laryngeal Mask with that of the LMA Classic laryngeal mask airway during controlled anaesthesia. Forty patients requiring intermittent positive pressure ventilation were studied using a randomised crossover design. The mean (SD) oropharyngeal leak pressure for the Ambu device (19 (7.5) cmH2O) was significantly greater than for the LMA Classic (15 (5.2) cmH2O; p = 0.004), and the number of attempts for successful insertions was significantly less (39 (50%) vs 45 (56%), respectively; p = 0.02). There was one failure to obtain a patent airway with the Ambu Laryngeal Mask and none with the LMA Classic. Insertion of the Ambu Laryngeal Mask required more manipulations to achieve a patent airway than did the LMA Classic (6 (15%) vs 1 (2.5%), respectively; p = 0.045), but the time taken for insertion was similar between the two groups. The incidence of trauma, grade of fibreoptic view, peak airway pressure and quality of ventilation during maintenance of anaesthesia were similar in both groups.