A program for sustained improvement in preventing ventilator associated pneumonia in an intensive care setting

Ventilator-associated pneumonia (VAP) is a common infection in the ICU. [1] Recent studies describe a rate of 1 to 4 cases per 1,000 ventilator-days, although this can reach up to 10 cases per 1,000 cases ventilator-days in neonates and surgical patients [2, 3]. The improvement in outcomes associated with recent initiatives suggest that many cases of VAP can be prevented by adhering to bundles of infection prevention measures [4, 5].

The attributable mortality of VAP is around 4% to 9% varying with definitions, case-mix, causative microorganisms, and treatment adequacy [6, 7]. VAP is also associated with considerable morbidity, due to increased length of hospital and ICU stay, prolonged mechanical ventilation and increased hospital expenses [8‐10], as well as excessive utilization of antimicrobials with correspondingly higher costs [8, 9].

As part of the 5 Million Lives campaign, endorsed by leading US agencies and professional societies, The Institute for Healthcare Improvement (IHI) recommends that all ICUs implement a ventilator bundle to reduce the incidence of VAP to zero [11]. Since 2007, we have implemented the VAP bundle in our ICU, including oral hygiene with 0.12% chlorhexidine and continuous aspiration of subglottic secretions (CASS) [4]. With these measures we were able to achieve zero incidence of VAP during a few months when a higher than 95% compliance rate with the VAP bundle was obtained [4]. However, to date there are no reports of sustained low incidence of VAP [4] (near zero).

The purpose of this quasi-experimental study was to evaluate whether the sustained implementation of the VAP bundle in our ICU could effectively reduce the incidence of ventilator-associated pneumonia (VAP).

Since 2007, we have set as a priority in our hospital the eradication of nosocomial infections. To this end, we have developed a set of best practices for prevention of ventilator associated pneumonia (VAP). In order to achieve a reduction in VAP rates, we have applied the Institute for Healthcare Improvement bundle model and also implemented other preventive measures (oral chlorhexidine 0.12% and CASS endotracheal tube). Our VAP rates are discussed on a monthly basis at a multidisciplinary meeting with our hospital’s chief executive officer (CEO) and other senior management representatives responsible for ensuring that healthcare practices support a program for infection prevention and control that effectively prevents VAP.

Many hospitals have achieved the goal of getting VAP to zero [14, 15], while others have managed to substantially reduce VAP rates, but believe that eliminating VAP in the intensive care unit may be an unrealistic goal [16]. In a previous publication [4], we have shown that this was only possible when the compliance with the VAP prevention bundle exceeded 95%, the CASS endotracheal tube was incorporated in daily practices and [17, 18] oral hygiene with chlorhexidine was implemented [19]. In a recent systematic review and meta-analysis of patients at risk for ventilator-associated pneumonia, the use of endotracheal tubes with subglottic secretion drainage was shown to effectively prevent ventilator-associated pneumonia and to be possibly associated with reduced duration of mechanical ventilation and length of ICU stay [18]. We believe this might be the reason for our reduced time and utilization rate of mechanical ventilation, together with the daily sedation vacation included in the VAP bundle. We also believe that obtaining the commitment of all members of the ICU team was ultimately a factor in our success in the implementation of these procedures over the years.

Klompas et al. [20] have called attention to the problems that may arise when we use VAP as a quality indicator, including difficulties with the subjectivity implied by the current VAP definition. Moreover, Edmond has pointed out that the “getting to zero” approach may be associated with adverse unintended consequences [21]. Moreover, the CDC/NHSN definition has been shown to have lower sensitivity than the American College of Chest Physicians definition [22]. Even though we consider it important to report VAP rates, we believe we should continuously report our compliance to the prevention measures (VAP bundle) and the adverse events associated with mechanical ventilation in ICU patients [23]. However, we were able to show that the procedures implemented since 2007 have contributed to a significant reduction in our infection rates (Figure 5) and to a decrease in the use of mechanical ventilation in recent years (Figure 4). It is important to note that our VAP surveillance was performed by trained infection control practitioners using the US Centers for Disease Control and Prevention/National Healthcare Safety Network (CDC/NHSN) definition [12] throughout the study period. Even though we have failed to demonstrate a statistically significant result using the segmented regression analysis of VAP prevention, we have achieved a zero infection rate by applying all the VAP prevention measures recommended in the literature [8, 9].

There are several limitations to this study. This is not a randomized trial but a quasi-experimental, interrupted time series study. Quasi-experimental study designs are frequently used when it is not logistically feasible to conduct a controlled trial. Thus, other unmeasured factors might have coincided with the interventions effective since April 2007 (implementation of the ventilator bundle), resulting in a decrease in VAP rates in our ICU. However, this seems unlikely because there had been no decrease in VAP rates over the previous several years (Figure 5). Data from our ICU in 2011 and in the first quarter of 2012 have shown that the VAP rate continues low (1.5 and 1.9, respectively). Finally, as this intervention was performed at a single medical center, it might be inappropriate to extrapolate our results (i.e. VAP mortality) to other hospitals. Even considering some aspects as the attributable mortality of VAP, other studies applying more sophisticated analysis such as multistate model that appropriately handle VAP as a time-dependent event or competing risk survival analysis have shown rates of attributable mortality as low as 10% [6, 24]. Despite these limitations, our study further support the assumption that controlling VAP rates can be a sustained with the monitoring of multiple performance measures and quality improvement efforts.

The process and the outcome measures for VAP presented here are derived from published guidelines and other relevant literature. While we recognize that the VAP definition may be subject to criticism due to its many subjective aspects, we managed to keep the whole team’s commitment to preventive measures for over two years, which demonstrates this is a sustainable program for preventing ventilator-associated pneumonia in the intensive care unit.