Application of a mechanical ventilation weaning protocol in a coronary unit
© BioMed Central Ltd 2007
Published: 19 June 2007
Weaning is the transitional period when a patient under mechanical ventilation (MV) transfers to unassisted spontaneous breathing. Failure in the discontinuation of ventilatory support is associated with an increase in the number of complications. The use of standardized guidelines to carry out weaning is already well established in general ICUs. The conditions most commonly seen in the coronary unit of care (CUC), such as acute myocardial ischemia, left ventricular dysfunction and after coronary artery bypass grafting surgery, however, cause completely different hemodynamic and circulatory alterations to those observed in other types of severely ill patients. The effects of mechanical ventilation and of weaning should therefore be tested specifically for these patients.
To compare MV weaning performed according to the application of a series of guidelines versus nonstandardized weaning in patients hospitalized in a CUC.
Initially a pilot study was performed with the aim of estimating the failure rate of MV weaning of patients hospitalized in the CUC. The results confirmed the necessity of improving the method then employed by the multidisciplinary team. Hence, 36 patients, who utilized MV for a period greater than 24 hours and were ready for weaning, were prospectively included in the study. The average age of the patients was 59.5 ± 16.4 years. The number of patients needed to include in the study was determined by calculating the sample size. The patients were then randomly placed into two groups: the experimental group (EG) and the control group (CG). In the EG, extubation was standardized according to the spontaneous respiratory test (SRT) of the American guidelines for weaning and was conducted by investigator in the study. For the CG, the SRT was also performed by the same investigator but without altering the extubation procedure employed, which was determined by the multidisciplinary team.
The groups were matched so there were no statistically significant differences in respect to gender, age, diagnoses at admission, ventilation parameters, physiological variables and APACHE II score. The time necessary for weaning was significantly shorter in the EG (2 hours and 24 minutes vs 70 hours; P = 0.0009). Sixteen patients in the CG were extubated, of which 11 (69%) did not fulfill the clinical criteria of the SRT. Of these 16 cases, 12 (75%) were reintubated and four (25%) were successfully weaned with all the successful cases among patients who passed the SRT. Of the 18 patients in the EG, 11 fulfilled the criteria for SRT and were extubated. Of these, eight (73%) cases were successful and three (27%) required reintubation. The reintubation rate was significantly higher in the CG (75% vs 25%; P = 0.0001).
The application of the weaning MV guidelines in heart disease patients hospitalized in the CUC reduces the time necessary to complete weaning, increases the success rate and reduces the reintubation rates.