Kavvadia V, Greenough A, Dimitriou G
Department of Child Health, Ruskin Wing, King's College School of Medicine and Dentistry, London, UK.
Eur J Pediatr. 2000 Apr;159(4):227-31. doi: 10.1007/s004310050059.
The aim of this study was to compare the results of lung function measurements made before and after extubation and ventilator settings recorded immediately prior to extubation with regard to their ability to predict extubation success in mechanically ventilated, prematurely born infants. Immediately after extubation all infants were nursed in an appropriate amount of humidified oxygen bled into a headbox. Functional residual capacity, spontaneous tidal volume and compliance of the respiratory system were measured both within 4 h before and within 24 h after extubation. The peak inspiratory pressure and inspired oxygen concentration immediately prior to extubation were recorded. The results were related to extubation failure: requirement for continuous positive airways pressure or re-ventilation within 48 h of extubation. A total of 30 infants, median gestational age 29 weeks (range 25-33 weeks) were studied at a median postnatal age of 3 days (range 1-6 days). Extubation failed in ten infants, who differed significantly from the rest of the cohort with regard to their post extubation functional residual capacity (FRC) (median 23, range 15.6-28.7 ml/kg versus 28.6, range 18.1-39.2 ml/kg, P<0.01) and their requirement for a higher inspired oxygen concentration post extubation (median 0.30, range 0.21-0.40 versus 0.22, range 0.21-0.36, P<0.05). An FRC of less than 26 ml/kg post extubation had the highest positive predictive value in predicting extubation failure.
A low lung volume performed best in predicting extubation failure when compared to the results of other lung function measurements and commonly used 'clinical' indices, i.e. ventilator settings. A low gestational age, however, was a better predictor of extubation failure than a low lung volume.
本研究的目的是比较机械通气早产儿拔管前后的肺功能测量结果以及拔管前即刻记录的呼吸机设置，以评估它们预测拔管成功的能力。拔管后，所有婴儿立即在头罩中给予适量的湿化氧气进行护理。分别在拔管前4小时内和拔管后24小时内测量功能残气量、自主潮气量和呼吸系统顺应性。记录拔管前即刻的吸气峰压和吸入氧浓度。将结果与拔管失败情况相关联：拔管后48小时内需要持续气道正压通气或再次机械通气。共研究了30例婴儿，中位胎龄29周（范围25 - 33周），中位出生后年龄3天（范围1 - 6天）。10例婴儿拔管失败，这些婴儿与其余队列相比，拔管后功能残气量（FRC）有显著差异（中位数23，范围15.6 - 28.7 ml/kg，而其余为28.6，范围18.1 - 39.2 ml/kg，P<0.01），且拔管后需要更高的吸入氧浓度（中位数0.30，范围0.21 - 0.40，而其余为0.22，范围0.21 - 0.36，P<0.05）。拔管后FRC小于26 ml/kg对预测拔管失败具有最高的阳性预测价值。
与其他肺功能测量结果和常用的“临床”指标（即呼吸机设置）相比，低肺容量在预测拔管失败方面表现最佳。然而，低胎龄比低肺容量更能预测拔管失败。
