Weaning protocols usually consist of three parts: 1) objective criteria to judge readiness to wean; 2) guidelines to decrease support gradually; and 3) criteria to assess readiness for extubation.([FOOTNOTE= McConville, J. F., & Kress, J. P. Weaning patients from the ventilator. N Engl J Med. 2012;367(23):2233-2239.],[ANCHOR=],[LINK=])
Prior to participation in a spontaneous breathing trial, patients must be evaluated for eligibility. Patients may be assessed for readiness for a spontaneous breathing trial by confirming the following:([FOOTNOTE=MacIntyre, N. R., Cook, D. J., Ely, E. W., Jr., et al. Evidence-based guidelines for weaning and discontinuing ventilatory support: a collective task force facilitated by the American College of Chest Physicians; the American Association for Respiratory Care; and the American College of Critical Care Medicine. Chest. 2001;120(6 Suppl):375S-395S.],[ANCHOR=],[LINK=])
A spontaneous breathing trial (SBT) is a focused assessment of a patient’s ability to breathe independently while receiving minimal or no respiratory support, and is typically considered the best way to see if a patient is ready to be extubated.([FOOTNOTE=Boles, J. M., Bion, J., Connors, A., et al. Weaning from mechanical ventilation. Eur Respir J. 2007;29(5):1033-1056.],[ANCHOR=],[LINK=]) Guidelines also suggest that a patient’s initial SBT should last at least 30 minutes but not more than 120 minutes. There are a number of different SBT methods that can be used.4 A recent Cochrane Report found generally limited differences in weaning success across PSV and T-tube SBT methods, though in patients where first-attempt SBT is successful, Pressure Support Ventilation appeared to be slightly more effective.([FOOTNOTE= Ladeira, M. T., Vital, F. M., Andriolo, R. B., Andriolo, B. N., Atallah, A. N., & Peccin, M. S. Pressure support versus T-tube for weaning from mechanical ventilation in adults. Cochrane Database Syst Rev. 2014(5):CD006056.],[ANCHOR=],[LINK=])
|T-Tube||The patient is disconnected from the ventilator and allowed to breathe spontaneously through a T-piece with supplemental oxygen.5|
|Pressure Support Ventilation||The patient remains connected to the ventilator and the PS value is adjusted to decrease the work of breathing (typically 5-10 cmH2O).5|
|Other methods||Use of synchronized intermittent mandatory ventilation (SIMV), continuous positive airway pressure (CPAP), and automatic tube compensation (ATC).3,([FOOTNOTE=Figueroa-Casas, J. B., Montoya, R., Arzabala, A., & Connery, S. M. Comparison between automatic tube compensation and continuous positive airway pressure during spontaneous breathing trials. Respir Care. 2010;55(5):549-554.],[ANCHOR=],[LINK=])|
The ARDS network, funded by the National Heart, Lung and Blood Institute (NHLBI) of the National Institutes of Health (NIH), was established to develop evidence for the management of ventilated patients with Acute Respiratory Distress Syndrome (ARDSnet.org). As such, ARDSnet trials have provided some of the most influential ventilation-related evidence of the past 20 years. The SBT eligibility criteria and spontaneous breathing trial method below are included in the ARDSnet ventilation protocol.
If all above criteria are met, initiate a trial of UP TO 120 minutes of spontaneous breathing with FiO2 ≤ 0.5 and PEEP ≤ 5:
Modified from ARDSnet.7
In ventilated patients, using effective protocols to better identify patients who are ready for weaning and to better manage the weaning process itself can significantly reduce the duration of ventilation and number of complications.1,([FOOTNOTE=Burns, K. E., Meade, M. O., Lessard, M. R., et al. Wean earlier and automatically with new technology (the WEAN study). A multicenter, pilot randomized controlled trial. Am J Respir Crit Care Med. 2013;187(11):1203-1211.],[ANCHOR=],[LINK=]),([FOOTNOTE=Cook, D. J., Walter, S. D., Cook, R. J., et al. Incidence of and risk factors for ventilator-associated pneumonia in critically ill patients. Ann Intern Med. 1998;129(6):433-440.],[ANCHOR=],[LINK=])
In a study by McLean et al., the authors instituted a 4-step process improvement model with the goal of improving protocol adherence and clinical outcomes. After implementing the model, the authors reported that protocol adherence improved to 21.2% coinciding with a significant reduction in the rate of unsuccessful extubation (3.0% vs. 12.7%; P=0.05).11
Dries et al., in a survey of 2 years' activity in a multidisciplinary surgical ICU, found that protocolized weaning resulted in a reduction in the number of patients failing extubation from 13.7% to 7.4% (P=0.013).10
In a Cochrane Review of 17 clinical studies encompassing 2,434 patients, Blackwood et al. found that protocolized weaning resulted a 26% reduction (P=0.0002) in the mean duration of mechanical ventilation.1
Marelich et al. studied the effect of a single ventilator management protocol (VMP) on the incidence of VAP. In this study, the VMP group tended to have less VAP (6%) as compared to the control group (15%; P= 0.061).13
In a 2002 study of 352 ICU patients, Iregui et al. found that after implementation of a computerized weaning guide, fewer patients developed VAP as compared to a control period (25 cases vs. 42 cases; P= 0.021).14
Dries et al. studied the effect of protocol-driven ventilator weaning on VAP; after protocol implementation, the number of VAP cases fell from 17 to 5 (P= 0.165).10
In a study by McLean et al., increased adherence to weaning protocols corresponded with a reduction in VAP incidence (19.7% vs. 34.9%), though the difference was not statistically significant (P= 0.14).11
In a randomized, controlled study in 300 mechanically ventilated ICU patients, Ely et al. found that protocolized weaning resulted in total ICU costs that were approximately $5,000 less in the intervention group compared to the control group ($15,740 vs. $20,890; P=0.03) and a tendency towards reduced overall costs ($26,229 vs. $29,048; P=0.3).([FOOTNOTE=Ely, E. W., Bennett, P. A., Bowton, D. L., Murphy, S. M., Florance, A. M., & Haponik, E. F. Large scale implementation of a respiratory therapist-driven protocol for ventilator weaning. Am J Respir Crit Care Med. 1999;159(2):439-446.],[ANCHOR=],[LINK=])
One study by Burns et al. calculated that implementation of standardized ventilation management programs, including protocol-driven sedation and weaning, resulted in more than $3 million in cost savings the first year of implementation, with an average savings of over $3,000 per case.12
Burns et al. demonstrated that the implementation of a multidisciplinary outcomes management (OM) process for mechanically ventilated patients, including standardized protocols for weaning and sedation use, resulted in a reduced mortality rate (31% vs. 38%; P=0.02).12
Multiple studies have demonstrated that even in the highly structured environment of clinical trials adherence to weaning protocols is low, ranging from 21-66%.11,15 These low rates may be a product of healthcare professionals perceiving protocols as removing clinical judgment from clinical decision making.11 In order to overcome this obstacle, McLean et al. demonstrated that a process improvement intervention program designed to improve weaning protocol adherence resulted in a 13-fold increase in adherence rates accompanied by a 4-fold decrease in reintubation.11
Weaning guidelines typically include strategies to reduce the duration of mechanical ventilation once intubated, earlier appreciation of readiness for an SBT, and a shorter process of discontinuation of mechanical ventilation after passing an SBT.
16. MacIntyre, N. R., Cook, D. J., Ely, E. W., Jr., et al. Evidence-based guidelines for weaning and discontinuing ventilatory support: a collective task force facilitated by the American College of Chest Physicians; the American Association for Respiratory Care; and the American College of Critical Care Medicine. Chest. 2001;120(6 Suppl):375S-395S.
17. Institute for Healthcare Improvement. How to Guide: Prevent Ventilator-Associated Pneumonia. http://www.ihi.org/resources/Pages/Tools/HowtoGuidePreventVAP.aspx. 2012.View Abstract