Cough Peak Flows and Extubation Outcomes

Background: Semiobjective methods of quantifying cough strength and endotracheal secretions have been demonstrated to predict extubation outcomes of patients who have passed a spontaneous breathing trial (SBT).

Hypothesis: Cough strength, measured by voluntary cough peak expiratory flow (PEF), and endotracheal secretions, measured volumetrically, predict extubation outcomes of patients who have passed an SBT.

Patient Population: Critically ill patients admitted to the medical ICU of a 300-bed community teaching hospital.

Methods: All patients who passed an SBT and were about to be extubated were studied. The best of three cough attempts, measured with an in-line spirometer, and the average hourly rate of suctioned secretions prior to extubation were recorded with other weaning parameters and demographic data.

Results: Ninety-five patients were studied before and after 115 extubations. There were 13 unsuccessful extubations. There were no differences in age, gender, duration of intubation, or APACHE (acute physiology and chronic health evaluation) II scores between successful and unsuccessful extubations. The magnitude of endotracheal secretions was not associated with outcomes. The PEF of patients with unsuccessful extubations was significantly lower than that of those with successful extubations (64.2 +/- 6.8 L/min vs 81.9 +/- 2.7 L/min, p = 0.03). Patients with unsuccessful extubations stayed longer in the ICU than those with successful extubations (11.7 +/- 2.1 days vs 5.3 +/- 0.4 days, p = 0.009). Those with PEF <or= 60 L/min were five times as likely to have unsuccessful extubations and were 19 times as likely to die on that hospital stay. PEF and the rapid shallow breathing index were independently associated with extubation outcomes, while only the PEF (<or= 60 L/min) was independently associated with in-hospital mortality.

Conclusion: These data suggest that cough strength, measured objectively, is a predictor of extubation outcome, morbidity, and mortality.