The purpose of the study was to assess the feasibility of average volume-assured pressure support (AVAPS) and determine factors that affect its use in patients with chronic obstructive pulmonary disease (COPD) and acute hypercapnic respiratory failure (AHRF).Methods:
Some 106 patients with COPD and AHRF received AVAPS. Patients who required invasive ventilation or died were included in the failed treatment group. Factors that affected failed treatment were determined using the Cox proportional hazard model. Analysis of variance was used to examine the variability of repeated measurements.Results:
Noninvasive ventilation was successful in 81 (76.4%) patients. The successful treatment group had a significantly higher baseline Glasgow Coma Score, pH, and ratio of partial pressure of oxygen (arterial) to fraction of inspired oxygen (P < .001, P = .008, and P < .001, respectively) but significantly lower Acute Physiology and Chronic Health Evaluation (APACHE) II and Charlson comorbidity index scores (P < .001). The change in partial pressure of carbon dioxide (arterial) during the first 2 hours was significantly greater in the successful treatment group (P = .008).Results:
Multivariate Cox regression analysis showed that percentage change in partial pressure of carbon dioxide (arterial) and APACHE II scores were significantly correlated to failed treatment (P = .02 and P = .01, respectively).Conclusion:
AVAPS can be used for AHRF associated with COPD. The risk of failed treatment is high for patients with higher baseline APACHE II and nonsignificant improvements in partial pressure of carbon dioxide (arterial) in the first 2 hours of treatment.