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Moderate application of a ventilator bundle was associated with improved outcome
- Frank Bloos, Gernot Marx (14 October 2009)
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Equating outcome benefit to poor care bundle compliance may be misleading
- Peter J O'Brien, Judith A. Joss, and Sally L. Crofts (9 September 2009)
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Frank Bloos University Hospital Jena, Dep. of Anesthesiology and Intensive Care Medicine, Gernot Marx
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Editor – We read with great interest the letter by O’Brien et al. especially since his group is experienced with the application of the ventilator bundle of the Institute of Health Care Improvement (IHI). Indeed, results from studies with a before and after design are more difficult to explain than controlled studies. However, we do not agree with some of the conclusions drawn by O’Brien et al. It is true that we observed differences between the two study populations which may have interfered with the duration of mechanical ventilation. Confounders are a general problem in this kind of studies which can be controlled by multivariate analysis. When we introduced propopfol usage – other sedatives were not different between the audits - and tracheostomy rates into the model, backrest elevation still contributed independently to the reduction on duration of mechanical ventilation. Therefore, the conclusion that even the incomplete application of the bundle resulted in a reduction of days on mechanical ventilation remains valid. It is not possible to conclude that differences in sedation usage is causally responsible for the reduction in mechanical ventilation. Although this conclusion may be one possible explanation, sedation usage is not an independent factor in this study. Sedation usage was an observed parameter and neither controlled by the study design nor prone to changes of standardized procedures. However, sedation usage depends on the physician’s intention to leave a patient on the respirator. We agree that it is a disadvantage of this study that we could not report differences in the VAP rates. However, there are no general accepted rules for VAP diagnosis [1, 2]. This makes it difficult to compare VAP rates between different institutions. It may make it also impossible to detect small changes in VAP rates. We discussed this topic in the manuscript but want to emphasize again that this study did not include all ICU patients but only with a duration of mechanical ventilation of more than 24 hours. Additionally, we intentionally did not report VAP rates per 1000 ventilator days. This parameter is prone to error when comparing patient populations with very different duration of mechanical ventilation [3]. We also agree to O’Brien et al. that high compliance rates need to be achieved. We most certainly did not want to conclude that one should aim for low compliance rates. As it was pointed out, quality control is a fastidious and time consuming process. A large multicenter trial about application of the sepsis bundles could also demonstrate only a limited increase in bundle compliance after one training cycle [4]. Nevertheless, there was a measurable effect on outcome. Last not least, only a few studies about the experience with the ventilator bundles have been published. For this reason, we found it worthwhile to share our experience with the ICU community. References 1. Shorr AF, Kollef MH: Ventilator-associated pneumonia: insights from recent clinical trials. Chest 2005; 128:583S-91S 2. Mehta RM, Niederman MS: Nosocomial pneumonia in the intensive care unit: controversies and dilemmas. J Intensive Care Med 2003; 18:175-88 3. Eggimann P, Hugonnet S, Sax H, et al: Ventilator-associated pneumonia: caveats for benchmarking. Intensive Care Med 2003; 29:2086-9 4. Ferrer R, Artigas A, Levy MM, et al. Improvement in process of care and outcome after a multicenter severe sepsis educational program in Spain. JAMA 2008; 299: 2294-303 Conflict of Interest:None declared |
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Peter J O'Brien, Specialist Registrar Intensive Care, Dundee, Judith A. Joss, and Sally L. Crofts
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Editor – We read with interest the article by Bloos et al 1 describing their experience of introducing a ventilator care bundle. Their claim that incomplete adoption of their adapted ventilator bundle, led to a statistically significant reduction in length of mechanical ventilation, whilst showing no positive effect upon the rate of ventilator associated pneumonia (VAP) is misleading given the differences between the two sample populations. Their adopted ventilator bundle differed from the Institute for Health Improvement’s (IHI) approved bundle 2 in the decision to omit the ‘sedation vacation’ or ‘readiness to wean’ component. Of the four elements included, DVT prophylaxis, gastric ulcer prophylaxis, semi recumbent position and lung protective ventilation, the main improvement in compliance appeared to be with attaining the semi recumbent position of >30°, from 24.9% to 49.6%. However the measured improvement was from 22.6° (18.4 – 26.2 IQR) to 26.7° (22.5-29.5 IQR) with p<0.01. We would question the clinical significance of this improvement. The authors’ conclusion that the improved compliance with their ventilator bundle from 15% to 33.8%, was responsible for the significant reduction in mechanical ventilation seems at odds with the experiences of other ICUs. This conclusion seems difficult to justify in the presence of the recognised differences between the two sample populations. The amount of sedation used was considerably less during the second audit cycle but the authors failed to report the contribution to duration of mechanical ventilation. Reduced sedation use has been shown to reduce the duration of mechanical ventilation in medical ICU patients 3. Additionally, the increased tracheostomy rate (19.5% vs 30.9% p=0.037) was shown to independently affect the duration of mechanical ventilation on multivariate analysis 1. The importance of VAP cannot be underestimated in the ICU setting. It is recognised that it is the consistent application of evidence-based interventions that reduces the rate of VAP and subsequently duration of mechanical ventilation and ICU length of stay, of which there is a known association 4. The results reported correspond to a VAP rate of 36.7 per 1000 ventilator days rising to 45.9 per 1000 ventilator days following the introduction of their ventilator bundle. This represents a high VAP rate in the context of most units. As one of the UK ICUs selected to pilot the introduction of care bundles as part of the ‘Safer Patient Initiative’, a collaboration between the IHI and the Health Foundation, we now have four years experience in the use of a ventilator bundle within the ICU setting. Our implementation of the IHI approved ventilator care bundle from August 2005 achieved an improvement of our VAP rate from 45.1 per 1000 ventilator days to 11.7 per 1000 ventilator days by the end of the year. Each component of the bundle was implemented using the IHI methodology – the model for improvement, and Plan, Do, Study, Act (PDSA) cycles 5. 95% compliance was achieved within six weeks. Our compliance is monitored within an ongoing quality improvement process and remains high. Our current VAP rate for 2009 is 4.9 per 1000 ventilator days. The IHI, which has driven the introduction of care bundles within the critical care setting states that the target for compliance should be 95%. This target is required to ensure consistent adoption and adherence to a bundle. The suggestion that 33.8% compliance with a ventilator bundle that does not include a sedation hold can reduce the duration of mechanical ventilation in the absence of a reduction of VAP would not be consistent with the current literature or our experience 4. It would seem plausible, given the differences between the two samples that there may be another confounding factor involved. References 1. Bloos F, Muller S, Harz A et al. Effects of training on the care of mechanically ventilated patients: a prospective cohort study. Brit J Anaes 2009; 103(2): 232-7 2.http://www.ihi.org/IHI/Topics/CriticalCare/IntensiveCare/Changes/ImplementtheVentilatorBundle.htm 3. Brook AD, Ahrens TS, Schaiff R et al. Effect of a nursing- implemented sedation protocol on the duration of mechanical ventilation. Crit Care Med 1999; 27:2609-15 4. Rello J, Ollendorf DA, Oster G et al. Epidemiology and outcomes of Ventilator-Associated Pneumonia in a large US Database. Chest 2002;122:2115-21 5.http://www.ihi.org/IHI/Programs/AudioAndWebPrograms/OnDemandPresentationMFI.htm Conflict of Interest:None declared |
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