Vento G, Tortorolo L, Zecca E, Rosano A, Matassa P G, Papacci P, Romagnoli C
Division of Neonatology, Department of Pediatrics, Università Cattolica del Sacro Cuore, Rome, Italy.
J Matern Fetal Neonatal Med. 2004 Mar;15(3):147-54. doi: 10.1080/14767050410001668239.
To validate the percentage of time spent below a target value of spontaneous expiratory minute ventilation (< 125 ml/min per kg) during a 2-h period of continuous positive airway pressure (CPAP) via an endotracheal tube (ETT) as a predictor of failed extubation in preterm infants.
Forty-one infants intubated for at least 24 h, with birth weight between 500 and 1000 g, who were clinically stable and at ventilator setting compatible with an extubation attempt, were studied during a 2-h period of ETT CPAP. Dynamic lung compliance and total lung resistance were measured during a period of quiet breathing, while tidal volume (Vt), respiratory rate and the corresponding spontaneous expiratory minute ventilation values were calculated for the complete recording period of 2 h using a customized computer program. The time each patient spent below the target spontaneous expiratory minute ventilation value was reported as a percentage of the total recorded time (% spontaneous expiratory minute ventilation < 125 ml/min per kg). Extubation failure was defined as the need for reintubation within 72 h.
Eleven out of 41 babies (26.8%) experienced failure of extubation (failure group) while 30 infants (73.2%) were successfully extubated (success group). There were no significant differences in dynamic lung compliance and lung resistance between the two groups, but the mean values of respiratory rate and spontaneous expiratory minute ventilation were significantly lower in the failure group than in the success group: 43 (37-56) breaths/min and 240 (160-353) ml/min per kg vs. 53 (28-67) breaths/min and 309 (223-434) ml/min per kg, respectively (p = 0.0129 and p = 0.0039). Moreover, the babies in whom extubation failed spent a longer time below the target value of spontaneous expiratory minute ventilation when compared with successfully extubated babies (p < 0.0001). Percentage of time spent with spontaneous expiratory minute ventilation < 125 ml/min per kg had a larger area than transcutaneous (Tc)PCO2, TcPO2 and pulse oxymetry saturation (SpO2) under the receiver operator characteristic curves.
The measurement of spontaneous expiratory minute ventilation prior to extubation could be useful in identifying those babies who are not ready for spontaneous ventilation.
验证经气管插管(ETT)进行持续气道正压通气(CPAP)2小时期间,低于目标自主呼气分钟通气量(<125ml/(min·kg))的时间百分比能否作为预测早产儿拔管失败的指标。
对41例插管至少24小时、出生体重在500至1000g之间、临床稳定且呼吸机设置适合进行拔管尝试的婴儿,在ETT CPAP 2小时期间进行研究。在安静呼吸期间测量动态肺顺应性和总肺阻力,同时使用定制的计算机程序在2小时的完整记录期内计算潮气量(Vt)、呼吸频率及相应的自主呼气分钟通气量值。报告每位患者低于目标自主呼气分钟通气量值的时间占总记录时间的百分比(自主呼气分钟通气量<125ml/(min·kg)的百分比)。拔管失败定义为在72小时内需要重新插管。
41例婴儿中有11例(26.8%)拔管失败(失败组),30例婴儿(73.2%)成功拔管(成功组)。两组间动态肺顺应性和肺阻力无显著差异,但失败组的呼吸频率和自主呼气分钟通气量平均值显著低于成功组:分别为43(37 - 56)次/分钟和240(160 - 353)ml/(min·kg),而成功组为53(28 - 67)次/分钟和309(223 - 434)ml/(min·kg)(p = 0.0129和p = 0.0039)。此外,与成功拔管的婴儿相比,拔管失败的婴儿低于目标自主呼气分钟通气量值的时间更长(p < 0.0001)。在受试者工作特征曲线下,自主呼气分钟通气量<125ml/(min·kg)的时间百分比曲线下面积大于经皮(Tc)PCO2、TcPO2和脉搏血氧饱和度(SpO2)。
拔管前测量自主呼气分钟通气量可能有助于识别那些尚未准备好进行自主通气的婴儿。