Joshi S, Sciacca R R, Solanki D R, Young W L, Mathru M M
Department of Anesthesiology, Columbia University College of Physicians and Surgeons, New York, New York, USA.
Anesthesiology. 1998 Nov;89(5):1141-6. doi: 10.1097/00000542-199811000-00014.
Reliable tests of correct anatomic placement of the laryngeal mask airway (LMA) may enhance safety during use and minimize the need for fiberoptic instrumentation during airway manipulation through the device. This study assessed the correlation between the outcomes of nine clinical tests to place the LMA and the anatomic position of the device as graded on a standard fiberoptic scale.
During 150 anesthetics, the outcome of nine clinical tests of correct placement was individually scored as satisfactory (positive) or unsatisfactory (negative) for clinical use of the LMA. Anatomic placement was assessed (by fiberoptic evaluation) by an anesthesiologist, who was blinded to the placement of the device, as grade 1, vocal cords not seen; grade 2, cords plus the anterior epiglottis seen; grade 3, cords plus the posterior epiglottis seen; and grade 4, only vocal cords seen. The outcomes of clinical tests were correlated with fiberoptic grade.
Tests that correlated with the fiberoptic grade were the ability to generate an airway pressure of 20 cm water, the ability to ventilate manually, a black line on the LMA in midline, anterior movement of the larynx, outward movement of the LMA on inflation of the cuff, and movements of the reservoir bag with spontaneous breathing. Two tests, ability to generate airway pressure of 20 cm water and ability to ventilate manually, correlated with fiberoptic grades 4 and 3 combined (i.e., the epiglottis was supported by the LMA) and grade 2 (the epiglottis was not supported by the LMA). Tests with poor correlation with fiberoptic grade were the presence of resistance at the end of insertion, inability to advance LMA after inflation of the cuff, and presence of a capnographic trace.
The outcome of clinical tests correlates with the anatomic placement of LMAs, as judged by fiberoptic examination. Two tests that best correlated with the fiberoptic grade were the ability to generate airway pressure of 20 cm water and the ability to ventilate manually.
可靠的喉罩气道（LMA）正确解剖位置测试可提高使用期间的安全性，并尽量减少通过该装置进行气道操作时对纤维光学器械的需求。本研究评估了九种放置LMA的临床测试结果与根据标准纤维光学量表分级的装置解剖位置之间的相关性。
在150例麻醉过程中，对于LMA的临床使用，九种正确放置的临床测试结果分别被评为满意（阳性）或不满意（阴性）。由一名对装置放置情况不知情的麻醉医生通过纤维光学评估来评估解剖位置，分为1级，未见声带；2级，可见声带加会厌前部；3级，可见声带加会厌后部；4级，仅见声带。临床测试结果与纤维光学分级相关。
与纤维光学分级相关的测试包括产生20厘米水柱气道压力的能力、手动通气的能力、LMA上的黑线位于中线、喉部向前移动、气囊充气时LMA向外移动以及自主呼吸时贮气囊的移动。两项测试，即产生20厘米水柱气道压力的能力和手动通气的能力，与纤维光学分级4级和3级合并（即会厌由LMA支撑）以及2级（会厌不由LMA支撑）相关。与纤维光学分级相关性较差的测试包括插入末端有阻力、气囊充气后无法推进LMA以及有二氧化碳图波形。
根据纤维光学检查判断，临床测试结果与LMA的解剖位置相关。与纤维光学分级相关性最佳的两项测试是产生20厘米水柱气道压力的能力和手动通气的能力。
