Weaning By Protocol is Safe and Effective
August 1, 1997 4 minutes read
Mechanical ventilation is one of the most commonly offered medical therapies in ICUs, and weaning patients from mechanical ventilation is a mainstay of respiratory care practice involving physicians, nurses, and respiratory therapists. While identifying the best method of weaning is an ongoing topic of research and remains controversial, the purpose of this study was to assess the efficacy and efficiency of using protocols to wean patients, as compared to the traditional practice of physicians individually directing the weaning process.
The study was conducted in four ICUs of two large university-affiliated teaching hospitals. All patients receiving mechanical ventilation in the medical and surgical ICUs of these two hospitals were eligible for this study, except for those with head or facial trauma. Patients were stratified by ICU site and randomized when mechanical ventilation was initiated. Each ICU had its own dedicated critical care nursing staff, and medical care was provided by assigned rotating house staff physicians. The medical directors of three of the ICUs were dedicated critical care physicians and had critical care fellows overseeing the housestaff physicians. The medical director of the fourth ICU was a part-time critical care physician without critical care fellows.
Before beginning the trial, the medical directors of each ICU developed protocols to guide the assessment of weaning readiness and the weaning process for patients in their own units. A one- month training period was used to familiarize all staff with the protocols. The primary outcome measure was duration of mechanical ventilation; secondary outcomes were needed for reintubation, hospital length of stay, hospital costs, and mortality.
The weaning protocols had similar criteria for assessing weaning readiness and weaning failure. Each patient’s underlying indication for mechanical ventilation had resolved or significantly improved; all patients demonstrated acceptable oxygenation and respiratory rate, hemodynamic stability, and mental capacity. Attending physicians of patients in the protocol-directed group were notified before weaning procedures were begun, and they could alter the process if desired.
Three weaning methods were used. A medical ICU and surgical ICU each used spontaneous breathing trials to assess weaning readiness; patients able to breathe between one and two hours without meeting weaning failure criteria were extubated. One medical ICU used intermittent mandatory ventilation (IMV) and gradual reduction of IMV breaths, with patients receiving less than 4 IMV breaths/min being placed on a ventilator rate of zero for 30 min to one hour prior to extubation. One surgical ICU utilized pressure support (PS) ventilation, with weaning accomplished by a gradual reduction in PS.
During the four-month study period, 357 patients were randomized and analyzed. The patients in the protocol- and physician-directed weaning groups were equivalent in number, age, gender, ethnicity, presence of ARDS or other organ dysfunction, type of ICU, and indication for mechanical ventilation. The median age of all patients was 66 years. The protocol-directed group did have a significantly greater rate of chronic obstructive pulmonary disease requiring medical treatment and significantly lower APACHE II scores than the physician-directed group (16.4 vs 17.7, respectively). Patients in the protocol-directed group were more likely to have their respiratory function measured prior to beginning the weaning process compared to the physician-directed group (59.2% vs 37.6%, respectively). The two groups were similar in measures of respiratory function and modes of mechanical ventilation used prior to beginning the weaning process. A similar number of patients in each group did not have weaning attempted because of their medical condition and died while receiving mechanical ventilation. Attending physicians altered the weaning process specified by the protocol in 7% of the patients; half of these patients had their weaning delayed, and the other half had earlier weaning and extubation than would have been expected if the protocol had been followed.
Duration of mechanical ventilation prior to the start of weaning was less in the protocol-directed group (39.6 h vs 58.3 h), as was the total duration of mechanical ventilation (69.4 h vs 102 h) when compared to the physician-directed group. While three of the four ICUs had shorter duration of mechanical ventilation, the significant difference was attributed to two of the four ICUs, with the protocol group in one of these ICUs having significantly lower APACHE II scores. The fourth ICU, with a part-time medical director, had longer mechanical ventilation duration (48 h vs 40 h) with the protocol; historically, much of the weaning process in this ICU had been delegated to the nursing staff prior to the study. There were no significant differences in hospital costs, length-of-stay, or mortality, although in the aggregate, hospital cost-savings for all patients in the protocol-directed group were nearly $43,000.
Although this study was not designed to compare weaning strategies, no significant differences were observed in duration of mechanical ventilation between the protocol-directed patients in the medical ICUs using either spontaneous breathing trials or IMV weaning. Likewise, there were no differences in the duration of mechanical ventilation between the protocol-directed patients in the surgical ICUs using PS ventilation or spontaneous breathing trials as a weaning strategy. (Kollef MH, et al. Crit Care Med 1997;25:567-574.)
COMMENT BY DOREEN M. ANARDI, RN
This study demonstrated that respiratory therapists and nurses, using protocols tailored to their practice, could safely and more quickly wean patients from mechanical ventilation than occurred with traditional physician-directed practice. The weaning process was begun earlier, contributing to shortened duration of mechanical ventilation. While this shortened duration of mechanical ventilation did not significantly reduce hospital costs, it may represent an important quality-of-life savings for these patients.
Comparison of weaning strategies in the protocol-directed patients demonstrated no difference in the duration of mechanical ventilation. This suggests that it may not be the specific strategy but rather how it is implemented that is the important factor in successful weaning.
There is increasing use of protocols to administer a variety of medical therapies in ICUs. Judicious application of protocols takes advantage of the presence of costly nursing and respiratory care practitioners already at the patient’s bedside, freeing the physician for activities that cannot be delegated. Methods of evaluation outlined in this paper can guide the application of protocol-directed interventions to improve efficiency, patient outcomes, and cost-effective therapy.
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