Role of sedation for agitated patients undergoing noninvasive ventilation: clinical practice in a tertiary referral hospital

BACKGROUND Although sedation is often required for agitated patients undergoing noninvasive ventilation (NIV), reports on its practical use have been few. This study aimed to evaluate the efficacy and safety of sedation for agitated patients undergoing NIV in clinical practice in a single hospital. METHODS We retrospectively reviewed sedated patients who received NIV due to acute respiratory failure from May 2007 to May 2012. Sedation level was controlled according to the Richmond Agitation Sedation Scale (RASS). Clinical background, sedatives, failure rate of sedation, and complications were evaluated by 1) sedative methods (intermittent only, switched to continuous, or initially continuous) and 2) code status (do-not-intubate [DNI] or non-DNI). RESULTS Of 3506 patients who received NIV, 120 (3.4 %) consecutive patients were analyzed. Sedation was performed only intermittently in 72 (60 %) patients, was switched to continuously in 37 (31 %) and was applied only continuously in 11 (9 %). Underlying diseases in 48 % were acute respiratory distress syndrome/acute lung injury/severe pneumonia or acute exacerbation of interstitial pneumonia. In non-DNI patients (n = 39), no patient required intubation due to agitation with continuous sedation, and in DNI patients (n = 81), 96 % of patients could continue NIV treatment. PaCO2 level changes (6.7 ± 15.1 mmHg vs. -2.0 ± 7.7 mmHg, P = 0.028) and mortality in DNI patients (81 % vs. 57 %, P = 0.020) were significantly greater in the continuous use group than in the intermittent use group. CONCLUSIONS According to RASS scores, sedation during NIV in proficient hospitals may be favorably used to potentially avoid NIV failure in agitated patients, even in those having diseases with poor evidence of the usefulness of NIV. However, with continuous use, we must be aware of an increased hypercapnic state and the possibility of increased mortality. Larger controlled studies are needed to better clarify the role of sedation in improving NIV outcomes in intolerant patients.