Impact of the opening of a ward-based noninvasive ventilation unit on critical care

Introduction

Noninvasive ventilation (NIV) is now the accepted first-line treatment for acidotic exacerbations of chronic obstructive pulmonary disease (COPD). Many hospitals perform NIV in a ward-based unit outside the ICU. Patients are still admitted to the ICU when failure of NIV may lead to mechanical ventilation, or for bed resource reasons. The impact of the opening of a ward-based NIV unit at University Hospital Aintree in July 2004 is described.

Methods

Patients admitted to the ICU with acute exacerbations of COPD were identified from the ICU database for the 3 years either side of the NIV unit opening and their case notes examined by a single person (JG).

Results

Fifty-seven patients admitted to the ICU were identified for the 6-year period (51% male, mean age 68.5 years), 32 from before the NIV unit opened and 25 after. There were no statistically significant differences in sex, age, forced expiratory volume in 1 second, percentage predicted forced expiratory volume in 1 second, WHO performance status and admission pH before and after the NIV unit opened. There was a trend towards a worse admission pCO₂ after the unit opened (P = 0.065). Forty out of 57 patients were deemed 'not for intubation' at the time of ICU admission. In all of these cases, the decision was made by the admitting intensivist rather than the referring physician. Ten patients were intubated before the NIV unit opened and three patients after (P = 0.004). The mean length of stay in critical care was 3.5 days (SD 5.2) and the mean hospital stay was 13.9 days (SD 12.0). Overall the ICU mortality rate was 23% and inpatient mortality was 30%. There were no statistically significant differences before and after the NIV unit opened.

Conclusion

The opening of a ward-based NIV unit had little impact on the workload of the ICU. Patients admitted to the ICU and markers of their disease and exacerbation severity were very similar before and after the unit opened. This may be explained by patients who would have previously been managed conservatively being admitted to the NIV unit, but the ICU population remaining similar. It is clear that most patients come to the ICU without a predefined intubation decision. Significantly fewer patients were intubated after the NIV unit opened, and the reasons for this are unclear. Comparison with NIV unit data is now required to establish their patient population and outcome.