Minute ventilation recovery time: a predictor of extubation outcome.
OBJECTIVE
To determine if minute ventilation (E) measured as a trend following the final weaning trial prior to extubation may identify patients ready for extubation and be useful as a predictive measure of extubation outcome.


METHODS
Prospective observational study.


METHODS
Community hospital medical/surgical ICU.


METHODS
Sixty-nine patients receiving mechanical ventilation enrolled in an ICU weaning protocol who underwent planned extubation during 6 months of prospective evaluation. The failed extubation group included patients reintubated within 7 days. Patients were excluded if they received ventilation by noninvasive mask, bilevel positive airway pressure, tracheostomy, or were self-extubated.


METHODS
Patients tolerating a spontaneous breathing trial (SBT) and ready for planned extubation were placed back on their pre-SBT ventilator settings for up to 25 min, during which respiratory parameters were recorded. Respiratory parameters (respiratory rate, tidal volume, E, rapid shallow breathing index [f/VT]) were obtained at three time points: baseline (pre-SBT), posttrial (immediate conclusion of SBT), and recovery (return to baseline). Patients were assumed to recover when E decreased to 110% of the predetermined baseline.


RESULTS
Fifty-nine patients were successfully extubated, and 10 patients required reintubation after 2.5 +/- 2.6 days (mean +/- SD). Both groups were similar in age, comorbid status, primary diagnosis, APACHE (acute physiology and chronic health evaluation) II score, mode of weaning, and SBT length (p > 0.1). Respiratory parameters measured were similar at all three time points studied (p > 0.1). E recovery time of successful extubations was significantly shorter than failed extubations (3.6 +/- 2.7 min vs 9.6 +/- 5.8 min, p < 0.011). Multiple logistic regression adjusted for age, sex, and severity of illness revealed that E recovery time was an independent predictor of extubation outcome (p < 0.01). The area under the receiver operating characteristic curve for E recovery time (0.85 +/- 0.07) was larger than that for baseline E, posttrial E, posttrial f/VT, or PaCO(2).


CONCLUSIONS
E recovery time is an easy-to-measure parameter that may assist in determining respiratory reserve. Preliminary data demonstrates that it may be a useful adjunct in the decision to discontinue mechanical ventilation.
Martinez
Anthony
A
Division of Critical Care, St. Agnes HealthCare, Baltimore, MD 21229, USA.
Seymour
Christopher
C
Nam
Myung
M
D000368:Aged; D000369:Aged, 80 and over; D001784:Blood Gas Analysis; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012372:ROC Curve; D015656:Respiratory Mechanics; D013990:Tidal Volume; D015300:Ventilator Weaning; D014939:Work of Breathing