Emergency airway management with laryngeal mask airway

When used correctly, laryngeal mask airway is a life saver. We report two cases wherein it was used for rescue airway management and as a ventilatory device during anesthesia. It is concluded that an anesthetist should be familiar with the use of this device.     

The laryngeal mask airway in emergency medicine

The Laryngeal Mask Airway (LMA) is an upper airway adjunct lying intermediate in function between the endotracheal tube and the oropharyngeal airway. It has gained wide acceptance since its introduction into United Kingdom anaesthetic practice in 1988. We review the principles of advanced airway management in the emergency department and examine the application of the LMA to this area. We conclude that the LMA may have a small role in pre-hospital and CPR airway management, and a very significant role in the management of difficult or failed endotracheal intubation.     

Pulse oximetry with the laryngeal mask airway

This study evaluated the accuracy of pulse oximetry measured by a modified laryngeal mask airway (LMA). Ten anaesthetized patients (ASA I-II, aged 18-45) undergoing elective knee arthroscopies (mean-duration 40 min) were studied. A transmission pulse oximeter probe/sound OHMEDA was attached on the back of LMA (sizes 4 and 5) in an area in contact with the floor of the laryngeal part of the pharynx. Pharyngeal pulse oximetry as well as LMA cuff pressure were monitored and recorded every 5 min from the time of insertion (T0) to removal (T8) and were compared to simultaneous finger pulse oximeter readings. At T2 the cuff was over-inflated to obtain a 100 cm H2O intracuff pressure. At T3 the cuff pressure was decreased at 60 cm H2O. Pharyngeal pulse oximetry correlated with finger pulse oximetry throughout the study and was not effected by over-inflation of the LMA. This modification of the LMA provides an accurate method of measuring pulse oximetry which may be of use in a variety of circumstances.     

The use of a laryngeal mask airway during percutaneous tracheostomy

Summary

Bedside percutaneous tracheostomy (PCT) for patients in intensive care units (ICU) is gaining popularity. Recently, the use of a laryngeal mask airway (LMA) to facilitate PCT has been described. We present a series of 18 patients where an LMA was inserted prior to PCT. This was successful in all but one patient. PCT could not be performed in this patient as oxygen desaturation had developed after inserting the LMA. The reason for this was probably an oedematous larynx, secondary to long-term intubation. Major bleeding in two patients [one of whom required packed red blood cell (RBC) transfusion] required surgical intervention and two patients had minor bleeding. No complications were related to the insertion or presence of the LMA during PCT, with the exception of the one patient cited above. The use of an LMA during PCT is a method of treatment worth noting in ICU patients. This technique may provide suitable conditions for performing PCT and is free from the complications associated with the presence of an endotracheal tube.     

食管引流型与标准型喉罩通气道用于正压通气的自身对照研究

目的采用随机自身对照设计方法比较食管引流型喉罩通气道(PLMA)和标准型喉罩通气道(SLMA)用于间歇正压通气的有效性。方法选择50例经美国麻醉医师协会(ASA)身体状态分级标准分为1~2级、拟在全身麻醉下实施择期整形外科手术患者。在常规麻醉诱导后,顺序插入PLMA和SLMA,将通气罩内压充气至60cmH2O(1cm H2O=0.098kPa),评价两种喉罩通气道充气前后的肺通气满意度和气道密封压,同时进行光导纤维支气管镜(FOB)评分,确定通气罩的解剖位置。然后将潮气量设定为10ml/kg实施间歇正压通气,记录间歇正压通气后连续5次呼吸的平均呼潮气量和平均吸气峰压。结果在通气罩未充气情况下,插入PLMA后有46例(92%)患者获得了良好和尚可的肺通气效果,而插入SLMA后仅有22例(44%)患者获得了良好和尚可的肺通气效果;PLMA的气道密封压显著高于SLMA(P<0.05)。将通气罩内压充气至60cmH2O,采用PLMA的50例患者均获得良好的肺通气效果,但采用SLMA时仅有28例获得良好的肺通气效果;PLMA所需的充气量和充气后获得的气道密封压均显著高于SLMA(P均<0.05)。采用PLMA时所有患者的气道密封压均高于或等于采用SLMA时;采用PLMA时除2例患者外,其他患者所需的充气量也均高于采用SLMA时。PLMA通气罩位置的FOB评分显著低于SLMA(P<0.05)。采用PLMA维持气道的29例患者和采用SLMA维持气道的21例患者的平均呼潮气量、吸气峰压及维持气道时间差异均无显著性(P均>0.05)。结论与SLMA相比,PLMA可为正压通气提供更好的气道密封压,而且对声门和食管上端具有潜在的隔离作用,用于正压通气时PLMA比SLMA更有效、更安全。     

Remifentanil and etomidate for laryngeal mask airway insertion

Etomidate does not depress the upper airway reflexes, making it difficult to insert a laryngeal mask airway (LMA) when using it for anaesthesia. This study investigated the effect of adding remifentanil to etomidate for LMA insertion. Fifty adult patients, undergoing cystoscopy, were randomized to two groups. The propofol-remifentanil group (n=25) received propofol anaesthesia induction (2.5 mg/kg) and a remifentanil bolus of 0.5 microg/kg, followed by a 2-min remifentanil infusion of 0.05 microg/kg per min. The etomidate-remifentanil group (n=25) received etomidate anaesthesia induction (0.3 mg/kg) and remifentanil as described. The LMA was inserted by a blinded anaesthetist who assessed a number of parameters. Only 13 LMAs were inserted at the first attempt in the etomidate-remifentanil group compared with 23 in the propofol-remifentanil group. Gagging, chest rigidity and myoclonus occurred significantly more frequently in the etomidate-remifentanil group. We conclude that the addition of remifentanil to etomidate anaesthesia induction does not improve LMA insertion.     

喉罩置入与喉镜引导下气管插管在全麻中的应用比较

目的：比较喉罩置入和喉镜引导下气管插管应用于全身麻醉的优缺点，为临床麻醉提供参考。方法：将46例ASAⅠ、Ⅰ级的行叶乳险癌根治术的患者随机分为喉罩胃入组（L组，23例1和喉镜引导下气管插管组（T组，23例），观察围术期的血流动力学变化及盯IL糖值变化，比较两组芬太尼的用量、应激反应、通气与气体交换的情况及麻醉并发症发生情况。结果：两组通气、气体交换良好；诱导后（气管导管喉罩置入前）、气管导管置入后1min、气管导管缑罩拔出即刻血流动力学改变显著，手术1h、气管导管缑罩拔出时血糖值增高显著，而以T组改变更为突出，T组应激反应比L组强烈；T组麻醉并发症高于L组。结论：喉罩置入应用于全身麻醉优喉镜引导下气管插管。     

压舌板辅助法在可弯曲喉罩置入中的应用

目的：探讨压舌板辅助手法放置可弯曲喉罩的可行性。方法：选择拟于可弯曲喉罩全麻下行择期手术的患者64例，性别不限，年龄18～80岁，ASAⅠ～Ⅲ级。采用随机信封法将其分为标准手指引导组和压舌板辅助组，每组32例。分别记录两组喉罩置入时间、口咽部泄露压、纤维支气管镜视野评分和首次置管成功率及术后24h内咽痛的发生情况。结果：最终62例患者的资料纳入统计分析，标准手指引导组31例、压舌板辅助组31例。压舌板辅助组患者纤维支气管镜视野评分高于标准手指引导组（Z=-4.241，P<0.001）；压舌板辅助组口咽部泄露压高于标准手指引导组（t=-4.474，P<0.001）。与标准手指引导组患者相比，压舌板辅助组置管时间较长（t=-15.171，P<0.001）。压舌板辅助组首次置管成功率（100%）与标准手指引导组（93.55%）差异无统计学意义。两组患者术后24h内均未发生咽痛情况。结论：压舌板辅助法置入可弯曲喉罩可明显提高喉罩对位准确率，提高喉罩口咽部密闭性，且不增加术后咽痛的发生率，值得在临床工作中推广应用。     

The laryngeal mask airway: a comprehensive review for the Emergency Physician

The Laryngeal Mask Airway (LMA) was developed in the 1980s, but has only recently begun to be used in Emergency Medicine. The LMA affords effective assisted ventilation without requiring endotracheal intubation or visualization of the glottis. In doing so, it is more efficacious than a bag-valve-mask apparatus, although the risk of aspiration of gastric contents persists, particularly if the device is not properly placed. The LMA also has significant potential utility in management of the difficult airway. Most reported clinical experience with the LMA has come from the operating room. This article provides an overview of the extensive potential utility of the LMA in the Emergency Department and prehospital settings as well as a comprehensive review of the pertinent advantages, disadvantages, and complications associated with its use.     

i-gel喉罩通气在无痛纤维支气管镜检查中的应用

目的观察i-gel喉罩通气在无痛纤维支气管镜检查中的应用效果。方法 ASA I-II级拟行无痛纤维支气管镜检查的患者60例,采用随机数字表法,将患者随机分为2组:i-gel喉罩组(I组,n=30)和表面麻醉组(C组,n=30)。前者通过i-gel喉罩联合T型密封接头实施控制通气,后者常规表面麻醉后行纤支镜检查。分别记录麻醉前(T0)、麻醉后纤支镜进入前(T1)、进镜至咽部(T2)、声门部(T3)、气管内(T4)及纤支镜取出后即刻(T5)的6个时点血压(BP)、心率(HR)和脉博血氧饱和度(SpO2),观察镜检期间不良反应;记录两组患者的镜检条件及镜检时间,调查麻醉满意度(由内镜医师评价)及患者满意度(由患者评价)。结果 I组患者术中血流动力学稳定,C组HR、MAP在各时点均升高,与T0比较差异有统计学意义(P<0.05),组间相应时点比较亦有统计学意义(P<0.05);I组患者检查中出现呛咳、憋气、喉痉挛及体动等不良反应明显少于C组(P<0.05)。I组患者的镜检条件明显优于C组[(8.27±1.53)分vs.(5.16±1.12)分,P<0.05],镜检时间短于C组[(9.83±2.53)min vs.(16.52±4.38)min,P<0.05]。I组患者均能在术毕3～8 min苏醒,麻醉满意度[(91.3±7.8)分vs.(6.04±5.7)分]及患者满意度[(93.8±8.3)分vs.(48.7±6.6)分]均高于C组(P<0.05)。结论 i-gel喉罩通气用于无痛纤支镜检查,能保证血流动力学稳定,有效控制患者的通气,克服了呼吸抑制问题,改善镜检条件,苏醒快速。     

Proseal喉罩在全身麻醉中的应用

目的 观察Proseal喉罩在全身麻醉中的安全性、可行性.方法 择期全麻手术病人40例,年龄18～65岁,ASAⅠ～Ⅱ级,随机分为喉罩组(PLMA组,20例)和气管插管组(TT组,20例).用纤维支气管镜观察PLMA的到位情况.记录患者心率(HR)、平均动脉压(MAP)、气道峰压(Pmax)、气道平均压(Pmean)、潮气量(VT)、分钟通气量(MV)、脉搏血氧饱和度(SPO2)、呼气末二氧化碳分压(PETCO2)的变化数值及相关并发症.结果 ①血液动力学的变化:PLMA组在置入期和拔除期平均动脉压、心率的变化较TT组小(P＜0.05).②通气效果:两组的Pmax、 Pmean 、VT、MV、 PETCO2数值随麻醉手术影响变化一致,组间比较无显著性差异(P＞0.05).③并发症:PLMA组并发症例数少于TT组,苏醒期躁动、术后声嘶、咽喉不适发生率明显少于TT组(P＜0.05).结论 与气管导管相比较 ,Proseal喉罩用于全麻手术操作简便,应激反应小,通气满意,且咽喉部并发症少,安全可靠.     

The roles of the laryngeal mask airway in emergency medicine

The laryngeal mask airway has a well established place in routine anaesthetic practice. Its potential role in emergency medicine is hampered by its failure to protect the airway from aspiration and to form a high pressure seal for controlled ventilation but supported by its ease of placement. This review discusses the uses of the laryngeal mask airway in the emergency situation. The laryngeal mask airway has a role as an alternative to the face mask in resuscitation. It has roles as an alternative airway when intubation has failed and as an aid to difficult intubation. In the prehospital setting, an additional specific indication for its use may be when access to a patient is limited making tracheal intubation impossible. Two recent modifications of the laryngeal mask airway are described. The intubating laryngeal mask airway is specifically designed for the difficult airway and the disposable laryngeal mask airway (Unique?) is undergoing trials in the UK for use by paramedical staff. The potential use of the intubating laryngeal mask airway in the emergency setting is discussed.     

Comparison of propofol and sevoflurane for laryngeal mask airway insertion

In this study, we compared haemodynamic changes, laryngeal mask airway (LMA) insertion time, and complications in patients anesthetized by inhalation of sevoflurane with those of intravenous induction with propofol. One hundred patients, aged between 20-40 years were enrolled in this study. Group 1 received propofol (2.5 mg/kg i.v.) and group 2 received sevoflurane (6%+50% N2O+50% O2) by inhalation using the tidal volume technique. LMA insertion time was found to be significantly longer in sevoflurane group than in propofol group. Mean arterial blood pressure was significantly lower within each group after induction in comparison to before induction values. In both groups, the LMA was successfully inserted in all patients. The quality of anaesthesia according to patients was significantly higher in the propofol group (80%) than in sevoflurane group (30%). Odor perception was significantly higher in sevoflurane group (84%) than in propofol group (38%). Apnoea was significantly higher in propofol group (40%) than in sevoflurane group (0%). Sevoflurane is an alternative to propofol for induction of anaesthesia and has a lower incidence of apnoea. Other complication rates are not higher than which propofol but the longer duration of induction time is a disadvantage.     

Feasibility study of epinephrine administration via laryngeal mask airway using a porcine model

The laryngeal mask airway (LMA) is gaining wide application as an alternative method of maintaining the airway in situations including general anaesthesia, for difficult airways and pre-hospital resuscitation. During resuscitation, drug administration via an LMA is sometimes warranted when vascular accesses cannot be established immediately. Therefore, we conducted a study on the feasibility of drug administration via the laryngeal mask airway. Twenty-four pigs were assigned into four groups according to the mode of epinephrine (adrenaline) administration: intravenous (20 microg/kg; Group 1); tracheal (50 microg/kg; Group 2), injection into the upper end of the LMA (50 microg/kg; Group 3), and via a catheter through the LMA into the trachea (50 microg/kg; Group 4). Arterial blood samples were drawn before and at 2, 4, 6, 8, 10, 12, 14, 16, and 18 min after epinephrine administration. Heart rates and arterial blood pressures were also recorded at the same time. The peak plasma epinephrine (PPE) levels were higher for Group 1 compared to the other groups, with Group 3 producing the lowest PPE levels. No significant difference was demonstrated comparing the PPE levels for Groups 2 and 4. Further, no differences were noted comparing the mean arterial blood pressure and heart rate between these two groups. In this non-arrest adult porcine model we conclude that epinephrine delivered via a catheter passing through the LMA can provide a similar effect as administration via the tracheal tube.     

The paxpress airway causes more pharyngeal irritation than the reusable laryngeal mask airway

This study aimed to determine whether the PAXpress airway (Vital Signs, Totawa, NJ) should replace the standard laryngeal mask airway (LMA Classic) in our practice. Records of patients who had been ventilated with a PAXpress airway or an LMA were examined. Responses of patients in the postanesthesia care unit (PACU) or from routine postoperative calls the following day were noted. Insertion of the airway was easy in all of the LMA patients but in only 20% of the PAXpress patients. Blood was noticed on 27% (4/15) of the PAXpress airways but on none of the LMAs. None of the LMA patients complained of pharyngeal soreness in the PACU, whereas 33% (5/15) in the PAXpress group had a sore throat. The next day, only 2 patients in the LMA group (13%) complained of a slightly sore throat. In the PAXpress group, all but 2 of the 13 patients interviewed (85%) reported a sore throat. The average degree of soreness for this group (4.5) was significantly higher than that reported in the LMA group (P < .001). The PAXpress airway is more likely to cause irritation (often severe) of the airway and, therefore, should not replace the standard LMA in our practice.