Increasing compliance with low tidal volume ventilation in the ICU with two nudge-based interventions: evaluation through intervention time-series analyses

Abstract

Objectives: Low tidal volume (TVe) ventilation improves outcomes for ventilated patients, and the majority of clinicians state they implement it. Unfortunately, most patients never receive low TVes. 'Nudges' influence decision-making with subtle cognitive mechanisms and are effective in many contexts. There have been few studies examining their impact on clinical decision-making. We investigated the impact of 2 interventions designed using principles from behavioural science on the deployment of low TVe ventilation in the intensive care unit (ICU).

Setting: University Hospitals Bristol, a tertiary, mixed medical and surgical ICU with 20 beds, admitting over 1300 patients per year.

Participants: Data were collected from 2144 consecutive patients receiving controlled mechanical ventilation for more than 1 hour between October 2010 and September 2014. Patients on controlled mechanical ventilation for more than 20 hours were included in the final analysis.

Interventions: (1) Default ventilator settings were adjusted to comply with low TVe targets from the initiation of ventilation unless actively changed by a clinician. (2) A large dashboard was deployed displaying TVes in the format mL/kg ideal body weight (IBW) with alerts when TVes were excessive.

Primary outcome measure: TVe in mL/kg IBW.

Findings: TVe was significantly lower in the defaults group. In the dashboard intervention, TVe fell more quickly and by a greater amount after a TVe of 8 mL/kg IBW was breached when compared with controls. This effect improved in each subsequent year for 3 years.

Conclusions: This study has demonstrated that adjustment of default ventilator settings and a dashboard with alerts for excessive TVe can significantly influence clinical decision-making. This offers a promising strategy to improve compliance with low TVe ventilation, and suggests that using insights from behavioural science has potential to improve the translation of evidence into practice.

Keywords: behavioural science; decision-making; low tidal volume ventilation; nudge.

Figure 1

Dashboard appearance.

Figure 2

Effect of defaults and starting value on mean tidal volume. Tidal volume is displayed as a function of hours the patient was on ventilation. Averages are 50% trimmed means, and shaded regions are bootstrapped SEs. The lines are best-fit lines fit to the raw data. Intercepts and slopes are shown for the best-fit lines in the main figure. Error bars are 95% CIs.

Figure 3

Tidal volume (TVe) following dashboard warning. Panels A and B show the average TVe as a function of the number of hours since TVe first crossed the warning threshold. A Shows the data split by predashboard and postdashboard, and B splits the dashboard data further into yearly postintervention periods. Averages are 50% trimmed means, and shaded regions are bootstrapped SEs. The lines are best-fit three-parameter exponential functions fit to the raw data. The black dashed line illustrates the threshold for dashboard warnings. C and D Show β weights for the best-fit lines in A and B respectively. Error bars are 95% CIs.