The laryngeal mask airway in pediatric radiotherapy

The use of the laryngeal mask airway, a new form of airway, is described in infants and young children receiving radiotherapy under general anesthesia. The laryngeal mask airway consists of a tube, at the distal end of which is attached an elliptically shaped cuff resembling a miniature face mask. The laryngeal mask is inserted blindly into the pharynx, and its cuff forms a low pressure seal around the larynx through which the patient can breathe spontaneously. No complications occurred during use of the laryngeal mask in 25 children who received 312 anesthetics. This experience suggests that the laryngeal mask airway has a valuable role in this situation and may contribute to the safety of anesthesia.     

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     

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.     

Propofol or sevoflurane for laryngeal mask airway insertion

PURPOSE: Sevoflurane is a volatile anesthetic agent, which combines rapid, smooth inhalational induction of anesthesia with rapid recovery, making it particularly suitable for day case anesthesia. The laryngeal mask airway is often also used in ambulatory anesthesia, with intravenous propofol being the agent of choice for its insertion. Our objective was to compare the conditions for laryngeal mask airway (LMA) insertion obtained by modified vital capacity breath sevoflurane inhalational induction of anesthesia with propofol intravenous induction. METHODS: Eighty-eight patients, aged 18-65 yr, ASA I-II, undergoing general anesthesia for elective surgery were randomized into two groups in a prospective, single-blind study. Patients in Group P (n=44) received 2.5 mg x kg(-1) propofol i.v. and in Group S (n=44) received sevoflurane 8% in nitrous oxide 50% and oxygen. Ventilation was not assisted. Laryngeal mask airway insertion was attempted at one minute intervals from loss of both verbal response and eyelash reflex, by an anesthesiologist unaware of the induction technique. Complications, such as coughing and head movement, were also noted at each attempt. RESULTS: Mean time to successful LMA insertion was 1.3 (1-3) min in P and 2.2 (1-3) min in S, P < 0.05. Eleven patients in Group P, (25%) required additional propofol compared with four (9%) in S, P < 0.05. Incidence of complications was similar in both groups and by 3 min, LMA was successfully inserted in all patients. CONCLUSION: Modified vital capacity breath inhalational induction with sevoflurane 8% is efficient for LMA insertion in most cases, but takes slightly longer than propofol.     

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.     

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。     

ProSeal laryngeal mask airway for cardiac surgery after airway rescue

We present the case of the successful use of a ProSeal laryngeal mask airway in a severe obese 41-year-old women with a difficult airway, scheduled to undergo cardiac surgery (off-pump coronary artery bypass). Two intubation attempts failed and face mask ventilation became impossible with rapidly falling peripheral oxygen saturation. A ProSeal laryngeal airway was railroaded over a tracheal tube guide, a gastric tube was inserted along the drain tube and the patient underwent positive pressure ventilation, resulting in normal gas exchange and an oropharyngeal leak pressure > 40 cm H2O. The decision was taken to proceed with the ProSeal as the airway during the surgical intervention. Surgery was uneventful and the ProSeal was removed on the ICU three hours later. This case reports illustrates the successful use of a guided insertion of the ProSeal laryngeal mask for airway rescue in cardiac surgery.     

Unusual foreign body airway obstruction after laryngeal mask airway insertion

Airway obstruction during general anesthesia is fairly common. Foreign body causing obstruction of the laryngeal mask airway is uncommon but can confuse the anesthesiologist trying to troubleshoot the cause of inability to ventilate. We present a case of complete airway obstruction with a nematode caught in the vertical bars of the laryngeal mask airway after its insertion.     

Intubating laryngeal mask airway

The Intubating Laryngeal Mask Airway (ILMA) was introduced into clinical practice in 1997 following numerous clinical trials involving 1110 patients. The success rate of blind intubation via the device after two attempts is 88% in "routine" cases. Successful intubation in a variety of difficult airway scenarios, including awake intubation, has been described, with the overall success rate in the 377 patients reported being approximately 98%. The use of the ILMA by the novice operator has also been investigated with conflicting reports as to its suitability for emergency intubation in this setting. Blind versus visualized intubation techniques have also been investigated. These techniques may provide some benefits in improved safety and success rates, although the evidence is not definitive. The use of a visualizing technique is recommended, especially whilst experience with intubation via the ILMA is being gained. The risk of oesophageal intubation is reported as 5% and one death has been described secondary to the complications of oesophageal perforation during blind intubation. Morbidity described with the use of the ILMA includes sore throat, hoarse voice and epiglottic oedema. Haemodynamic changes associated with intubation via the ILMA are of minimal clinical consequence. The ILMA is a valuable adjunct to the airway management armamentarium, especially in cases of difficult airway management. Success with the device is more likely if the head of the patient is maintained in the neutral position, when the operator has practised at least 20 previous insertions and when the accompanying lubricated armoured tube is used.     

The laryngeal mask airway

A new form of airway has recently been described, which is introduced blindly into the hypopharynx to form a seal around the larynx, so permitting spontaneous or positive pressure ventilation without penetration of the larynx or oesophagus. The further development of this new airway is described and the results of 18 months' clinical experience are presented. The airway was used successfully in 118 patients, 17 of whom received controlled ventilation of their lungs. It was used in place of the facemask in routine anaesthesia, and was of particular value in ophthalmic, dental and ear, nose and throat procedures and where difficulties with the airway were expected. The incidence of sore throat and other problems was low. Experience of more than 500 cases suggests that the laryngeal mask airway may have a valuable r?le to play in all types of inhalational anaesthesia, while its proven value in some cases of difficult intubation indicates that it may contribute significantly to the safety of general anaesthesia.     

The laryngeal mask airway

A prototype size 3 laryngeal mask was used in 100 patients by 18 anaesthetists with no previous experience of its use. A clear and unobstructed airway was obtained in 98% of patients, without requiring support of the jaw, thus leaving the anaesthetists' hands entirely free. The patency of the airway did not deteriorate during the course of the anaesthetic. In 10 patients there was obstruction of the airway at the first attempt to place it without the introducer and this obstruction appeared to be as a result of downfolding of the epiglottis. Subsequent attempts at passage were successful in all 10 patients. The seal between the mask and the larynx was adequate for artificial ventilation of the patients, but the mean leak pressure was 1.7 kPa.