Leitch E A, Moran J L, Grealy B
Intensive Care Unit, Queen Elizabeth Hospital, Wodville, Australia.
Intensive Care Med. 1996 Aug;22(8):752-9. doi: 10.1007/BF01709517.
To assess the outcome of a clinical judgement-based approach to weaning and extubation and to adduce the predictive accuracy of various mechanical respiratory indices measured in parallel.
Prospective study.
Multidisciplinary intensive care unit at a university teaching hospital.
163 consecutive mechanically ventilated patients, excluding tracheotomy, for weaning trial and extubation.
Using bedside clinical assessment, aided by arterial gas analysis, patients were weaned from mechanical ventilation to spontaneous ventilation via to continuous positive airway pressure (CPAP) circuit (with pressure support) of a microprocessor-controlled ventilator. Extubation occurred from the CPAP circuit at 7 cmH2O pressure support, fractional inspired oxygen (FIO2) < or = 0.5 and CPAP level of < or = 5 cmH2O, such that the partial pressure of oxygen in arterial blood (PaO2) was > or = 65 mmHg. Before extubation, observation for a 1-h (T0 and T60) trial period allowed measurement of vital capacity (VC), expired minute volume (VE), respiratory rate/tidal volume (f/VT) and maximal inspiratory pressure (MIP) using a one-way valve technique over 25 s.
Over 7 months, 163 patients (62 females and 101 males; mean (SD) age 64(15) years) were considered. There were 91 surgical (18 with chronic obstructive pulmonary disease; COPD) and 72 medical (28 with COPD) patients. Ventilation was for > or = 1 day (median 5 days, range 1-31) in 115 [group I; APACHE II score 23(8)] and < or = 1 day in 48 [Group II; APACHE II score 17(6)]. Three patients (all Group I: 2 surgical, 1 medical) were reintubated within 24 h, an overall extubation failure rate of 1.8%. In group I, at T0, PaO2/FIO2 was 238(65), f/VT 50(26), MIP 44(21) cmH2O, VE 10.6(3.7) l/min, VC 13(5) ml/kg. Cardiorespiratory variables did not change significantly in either group, T0 to T60. For prediction of reintubation (n = 163), only VE (threshold > 10 l/min) and f/VT (threshold > 100) demonstrated moderate sensitivity and specificity at T60: 67 and 52% and 33 and 94%, respectively.
Bedside clinical judgement of weaning and extubation produces satisfactory outcomes. As a routine, mechanical predictive indices have limited utility.
评估基于临床判断的撤机和拔管方法的结果，并探讨同时测量的各种机械通气指标的预测准确性。
前瞻性研究。
一所大学教学医院的多学科重症监护病房。
163例连续接受机械通气的患者，不包括行气管切开术者，进行撤机试验和拔管。
借助动脉血气分析，通过床边临床评估，使用微处理器控制呼吸机的持续气道正压通气（CPAP）回路（带压力支持），将患者从机械通气撤至自主通气。当压力支持为7 cmH₂O、吸入氧分数（FIO₂）≤0.5且CPAP水平≤5 cmH₂O，使动脉血氧分压（PaO₂）≥65 mmHg时，从CPAP回路进行拔管。拔管前，观察1小时（T0和T60）试验期，使用单向阀技术在25秒内测量肺活量（VC）、每分钟呼出量（VE）、呼吸频率/潮气量（f/VT）和最大吸气压力（MIP）。
在7个月的时间里，共纳入163例患者（62例女性和101例男性；平均（标准差）年龄64（15）岁）。其中91例为外科患者（18例患有慢性阻塞性肺疾病；COPD），72例为内科患者（28例患有COPD）。115例患者（I组；急性生理与慢性健康状况评分系统II（APACHE II）评分为23（8））机械通气≥1天（中位数为5天，范围1 - 31天），48例患者（II组；APACHE II评分为17（6））机械通气≤1天。3例患者（均为I组：2例外科患者，1例内科患者）在24小时内重新插管，总体拔管失败率为1.8%。在I组中，T0时，PaO₂/FIO₂为238（65），f/VT为50（26），MIP为44（21）cmH₂O，VE为10.6（3.7）l/min，VC为13（5）ml/kg。两组从T0到T60，心肺变量均无显著变化。对于再插管的预测（n = 163），仅VE（阈值>10 l/min）和f/VT（阈值>100）在T60时显示出中等的敏感性和特异性：分别为67%和52%，以及33%和94%。
床边临床判断撤机和拔管可产生满意的结果。作为常规方法，机械预测指标的效用有限。
