Litman R S, Berkowitz R J, Ward D S
Department of Pediatrics, University of Rochester School of Medicine and Dentistry, NY, USA.
Arch Pediatr Adolesc Med. 1996 Jul;150(7):671-5. doi: 10.1001/archpedi.1996.02170320017002.
To determine the ventilatory effects and levels of consciousness achieved during sedation with the combination of oral midazolam and inhaled nitrous oxide.
Case series.
Surgical suite.
Twenty-two consecutive children, aged 1 to 3 years, were seen for elective, ambulatory surgery.
Patients were premedicated with oral midazolam hydrochloride, 0.5 mg/kg, and then breathed 4 concentrations of nitrous oxide (N2O) in oxygen (15%, 30%, 45%, and 60%) for 4 minutes at each concentration prior to induction of general anesthesia.
Levels of consciousness (conscious vs deep sedation) and ventilatory parameters: respiratory rate, end-tidal carbon dioxide tension (PETCO2), and oxyhemoglobin saturation (SPO2). Upper airway obstruction was diagnosed by clinical assessment by an experienced pediatric anesthesiologist (R.S.L.) and respiratory impedance plethysmography.
During inhalation of N2O, 12 of the 20 children demonstrated a mild degree of ventilatory depression; PETCO2 values were equal to or greater than 45 mm Hg during at least 2 concentrations of N2O studied. There were no significant changes in SPO2 or PETCO2 with increasing concentrations of N2O (P > .05). Respiratory rates tended to be lower during inhalation of 15% N2O than at higher concentrations (P = .05). No child developed upper airway obstruction or hypoxemia (SPO2 < 92%) at any level of N2O inhalation. Sedation scores were significantly higher at 60% N2O than at all other concentrations of N2O (P < .02) At 15% N2O, 12 children were not clinically sedated, 8 children met the American Academy of Pediatrics definition of conscious sedation, and no child met the definition of deep sedation. At 30% N2O, 10 children were not clinically sedated, 9 met the definition of conscious sedation, and 1 child met the definition of deep sedation. At 45% N2O, 9 children were not clinically sedated, 9 met the definition of conscious sedation, and 2 met the definition of deep sedation. At 60% N2O, 6 children were not clinically sedated, 6 met the definition of conscious sedation, 6 met the definition of deep sedation, and 1 child progressed to a deeper level of sedation in that there was no response to a painful stimulus. One child was withdrawn from the study during inhalation of 45% N2O because of emesis.
The combination of oral midazolam, 0.5 mg/kg, and up to 60% inhaled N2O caused mild ventilatory depression in some children and resulted in a progression from conscious to deep sedation beginning at 30% N2O. When using this particular combination of sedatives, practitioners should monitor each child's mental status continuously and adhere to the appropriate published guidelines for the monitoring and management of such patients.
确定口服咪达唑仑与吸入氧化亚氮联合镇静时的通气效果及意识水平。
病例系列研究。
外科手术室。
连续22例1至3岁择期门诊手术患儿。
患者术前口服0.5mg/kg盐酸咪达唑仑进行预处理，然后在全身麻醉诱导前，依次吸入4种浓度（15%、30%、45%和60%）的氧化亚氮（N₂O）与氧气的混合气体，每种浓度持续4分钟。
意识水平（清醒与深度镇静）及通气参数：呼吸频率、呼气末二氧化碳分压（PETCO₂）和氧合血红蛋白饱和度（SPO₂）。由经验丰富的儿科麻醉医生（R.S.L.）通过临床评估及呼吸阻抗体积描记法诊断上呼吸道梗阻。
吸入N₂O期间，20例患儿中有12例出现轻度通气抑制；在至少2种研究浓度的N₂O吸入过程中，PETCO₂值等于或大于45mmHg。随着N₂O浓度增加，SPO₂或PETCO₂无显著变化（P>.05）。吸入15%N₂O时的呼吸频率往往低于较高浓度时（P = .05）。在任何N₂O吸入水平下，均无患儿出现上呼吸道梗阻或低氧血症（SPO₂<92%）。60%N₂O时的镇静评分显著高于其他所有N₂O浓度（P<.02）。在15%N₂O时，12例患儿未达到临床镇静，8例符合美国儿科学会的清醒镇静定义，无患儿符合深度镇静定义。在30%N₂O时，10例患儿未达到临床镇静，9例符合清醒镇静定义，1例符合深度镇静定义。在45%N₂O时，9例患儿未达到临床镇静，9例符合清醒镇静定义，2例符合深度镇静定义。在60%N₂O时，6例患儿未达到临床镇静，6例符合清醒镇静定义，6例符合深度镇静定义，1例患儿进展至更深的镇静水平，即对疼痛刺激无反应。1例患儿在吸入45%N₂O时因呕吐退出研究。
0.5mg/kg口服咪达唑仑与高达60%吸入N₂O联合使用，在部分患儿中引起轻度通气抑制，并导致从30%N₂O开始从清醒镇静进展至深度镇静。使用这种特定的镇静剂组合时，从业者应持续监测每个患儿的精神状态，并遵循针对此类患者监测和管理的适当公开指南。
