title: Course of weaning from prolonged mechanical ventilation after cardiac surgery.
abstract: In order to determine the temporal pattern of weaning from mechanical ventilation for patients undergoing prolonged mechanical ventilation after cardiac surgery, we performed a retrospective review of 21 patients' weaning courses at our long-term acute care hospital. Using multiple regression analysis of an estimate of individual patients' percentage of mechanical ventilator support per day (%MVSD), we determined that 14 of 21 patients (67%) showed a statistically significant quadratic or cubic relationship between time and % MVSD. These patients showed little or no improvement in their ventilator dependence until a point in time when, abruptly, they began to make rapid progress (a "wean turning point"), after which they progressed to discontinuation of mechanical ventilation in a relatively short period of time. The other 7 patients appeared to have a similar weaning pattern, although the data were not statistically significant. Most patients in the study group weaned from the ventilator through a specific temporal pattern that is newly described herein. Data analysis suggested that the mechanism for the development of a wean turning point was improvement of pulmonary mechanics rather than improvement in gas exchange or respiratory load. Although these observations need to be confirmed by a prospective trial, they may have implications for weaning cardiac surgery patients from prolonged mechanical ventilation, and possibly for weaning a broader group of patients who require prolonged mechanical ventilation.
authors.affiliation: Department of Medicine, Baylor College of Medicine, USA. jph@houstonlungdocs.com
authors.forename: James P
authors.initials: JP
authors.lastname: Herlihy
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Koch
authors.forename: Robert
authors.initials: R
authors.lastname: Jackson
authors.forename: Hope
authors.initials: H
authors.lastname: Nora
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D006348:Cardiac Surgical Procedures; D015897:Comorbidity; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors; D015300:Ventilator Weaning / Q000379:methods; D014939:Work of Breathing