Theerapongpakdee Sunchai, Phanpanusit Thanyathorn, Horatanaruang Duenpen, Bunsangjaroen Piyaporn, Limpkulwathanaporn Prapapan, Thananun Maneerut, Nonlhaopol Duangthida
Department of Anesthesiology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand.
J Med Assoc Thai. 2009 May;92(5):667-71.
Baby EAR circuit is a new modified enclosed afferent reservoir anesthetic breathing system for pediatric patients. By following His Majesty the King of Thailand's self-sufficiency philosophy, the circuit is simple and made of low-cost and easy-to-find materials found in the operating room. This present study was to investigate clinical use of the circuit and to find the optimal fresh gas flow in clinical setting.
A prospective descriptive study was conducted in pediatric patients, weighed 5-20 kg, anesthetized for surgery. The Baby EAR breathing circuit was used for general anesthesia with endotracheal tube and control ventilation. Different fresh gas flow of 3, 2.5, 2 and 1.5 liter per minute (LPM) was used consecutively. The authors recorded end-tidal carbon dioxide (EtCO2) and mean inspiratory carbon dioxide (ImCO2) while using fresh gas flow at 3, 2.5, 2, and 1.5 LPM. EtCO2 of 35-45 mmHg and ImCO2 of < 6 mmHg were considered clinically acceptable.
Fifty patients were enrolled. Mean value (95% CI) of EtCO2 at fresh gas flow rate of 1.5, 2, 2.5, and 3 LPM were 39.6 (39.2, 40.9), 36.7 (35.5, 37.8), 35.4 (34.3, 36.4), and 35.4 (34.3, 36.4) mmHg respectively. Mean value (95% CI) of ImCO2 at fresh gas flow rate of 1.5, 2, 2.5, and 3 LPM were 4.0 (3.0, 4.9), 2.4 (1.7, 3.0), 1.8 (0.9, 2.6), and 1.3 (0.9, 1.7) mmHg respectively. Percentage of patients (95% CI) who had clinically acceptable EtCO2 and ImCO2 at fresh gas flow rate of 1.5, 2, 2.5, and 3 LPM were 70% (56.2, 80.9), 92% (81.2, 96.8), 98% (89.5, 99.6), and 100% (92.9, 100) respectively. No patients had serious complications.
Baby EAR circuit can be made economically and used safely for general anesthesia with control ventilation in pediatric patients weighing 5 to 20 kg at optimal fresh gas flow of 3 LPM.
婴儿EAR回路是一种新型改良的封闭式传入储液器麻醉呼吸系统，用于儿科患者。遵循泰国国王陛下的自给自足理念，该回路简单，由手术室中低成本且易于找到的材料制成。本研究旨在调查该回路的临床应用情况，并找出临床环境中的最佳新鲜气体流量。
对体重5 - 20千克、接受手术麻醉的儿科患者进行前瞻性描述性研究。婴儿EAR呼吸回路用于气管插管全身麻醉并控制通气。依次使用每分钟3、2.5、2和1.5升（LPM）的不同新鲜气体流量。作者在使用3、2.5、2和1.5 LPM新鲜气体流量时记录呼气末二氧化碳（EtCO2）和平均吸气二氧化碳（ImCO2）。EtCO2为35 - 45 mmHg且ImCO2 < 6 mmHg被认为在临床上可接受。
共纳入50例患者。新鲜气体流量为1.5、2、2.5和3 LPM时，EtCO2的平均值（95%可信区间）分别为39.6（39.2, 40.9）、36.7（35.5, 37.8）、35.4（34.3, 36.4）和35.4（34.3, 36.4）mmHg。新鲜气体流量为1.5、2、2.5和3 LPM时，ImCO2的平均值（95%可信区间）分别为4.0（3.0, 4.9）、2.4（1.7, 3.0）、1.8（0.9, 2.6）和1.3（0.9, 1.7）mmHg。新鲜气体流量为1.5、2、2.5和3 LPM时，EtCO2和ImCO2在临床上可接受的患者百分比（95%可信区间）分别为70%（56.2, 80.9）、92%（81.2, 96.8）、98%（89.5, 99.6）和100%（92.9, 100）。无患者出现严重并发症。
婴儿EAR回路制作成本低，可安全用于体重5至20千克儿科患者的气管插管全身麻醉并控制通气，最佳新鲜气体流量为3 LPM。
