咳嗽峰流速对拔管结果预测的临床研究

目的 探讨咳嗽峰流速(CPEF)测定对患者拔管脱机结果的预测价值及对预后的影响.方法 选择本院重症监护病房(ICU)2006年11月-2007年12月的200例拔管脱机患者进行前瞻性研究.患者均为经口气管插管接呼吸机辅助呼吸超过24 h者,其意识清楚能合作,且均顺利通过自主呼吸试验30 min.拔管前嘱患者咳嗽,用呼吸机内置肺流量计测定CPEF,取3次最强咳嗽时流速的平均值作为最后测定值.拔管后仔细观察患者的咳嗽情况,按实际咳嗽能力大小将其分为强、中、弱3个等级,如果72 h内患者无需再插管即为拔管脱机成功,同时记录咳嗽能力与拔管结果之间的关系.结果 200例患者中172例拔管成功,28例拔管失败.拔管成功和失败的患者在性别、年龄、疾病严重程度、自主呼吸试验时生命体征等方面比较差异无统计学意义.CPEF是拔管结果的独立预测因子[比值比(OR)<1].区分拔管成功与否的CPEF最佳临界值是58.5 L/min,当CPEF≤58.5 L/min时预测拔管失败的特异性为68.0%,敏感性为71.4%;阳性预测值为0.16,阴性预测值为0.94.拔管脱机的患者咳嗽能力多为"强",极少数为"中";而失败患者咳嗽能力多为"中"或"弱",能力"强"者仅3例.结论 当患者自主呼吸能力逐渐恢复并达到能够完成自主呼吸试验时,气道条件的参数是决定患者拔管结果的重要预测指标.对意识清楚能合作、能通过自主呼吸试验的患者,CPEF是拔管结果强有力的预测因子,是影响拔管成功与否的独立危险因子.CPEF>58.5 L/min的患者拔管成功率高,预后较好;反之,≤58.5 L/ min的患者拔管成功率较低.导致失败的原因多为咯痰不利,咳嗽能力强的患者脱机成功率高,脱机失败的患者预后较差.

A study of cough peak expiratory flow in predicting extubation outcome

Objective To study the value of cough peak expiratory flow (CPEF) in predicting extubation outcome of patients. Methods A prospective study of 200 adult patients was conducted and treated in the Third Central Hospital intensive care unit (ICU), receiving mechanical ventilation (MV) via an endotracheal tube during November 2006 through December 2007. All the patients received MV longer than 24 hours. They were conscious and cooperative at the time of extubation. Extubation was successful after 30 minutes of spontaneous breathing trial (SBT). They were asked to cough for three times, during which CPEF was measured with an in-line spirometer, and the average value was recorded. They were classified as strong, moderate, and weak according to the ability to cough. If the patients did not require reintubation within 72 hours, extubation was noted as successful. Results In 200 patients, in 172 patients extubation was successful and failed in 28 patients. Sex, age, severity of illness and vital signs during SBT showed no difference between patients with successful extubation and patients with unsuccessful extubation. CPEF was the independent predictor for the extubation outcome [odds ratio (OR)<1]. The cut-point was 58.5 L/min. CPEF≤58.5 L/min had a specificity of 68.0% and sensitivity of 71.4% in predicting extubation failure. The positive predicted value was 0.16, and the negative predicted value was 0.94. The cough strength in patients with successful extubation was almost always "strong", and in very few it was "mediun". In those extubation failed, there were only 3 patients showed strong cough strength, and for the rest it was "moderate" or "weak". Conclusion After patients have recovered from respiratory failure and SBT is successful, factors affecting airway competence, such as cough strength, may be important predictors of extubation outcome. The study confirmes that CPEF is a strong and independent predictor of extubation outcome when the patient is mentally clear and has a successful SBT. When the CPEF>58.5 L/min, the successful rate is high. On the contrary, when the CPEF≤58.5 L/min, the unsuccessful rate is high. Failure is often due to poor cough. The extubation outcome is highly correlated with cough strength. The prognosis in patients with failure is poor.