Predictors of successful noninvasive ventilation treatment for patients suffering acute respiratory failure

Background: To identify predictors of successful noninvasive ventilation (NIV) treatment for patients with acute respiratory failure. Methods: This was a prospective intervention study of the intensive care unit of a teaching hospital in Chia-Yi, Taiwan. Patients were enrolled if they had acute respiratory failure and had been admitted to the intensive care unit of our hospital between October 1, 2004 and September 30, 2005 inclusively. Results: All 86 patients who satisfied the study's inclusion criteria agreed to participate in the study, and each patient was followed-up until the discontinuation of NIV treatment or their death. We measured the Acute Physiology and Chronic Health Evaluation (APACHE) II score prior to their treatment and also conducted serial measurements of respiratory rate (RR), tidal volume, rapid shallow breathing index, maximal inspiratory pressure (P_Imax), and maximal expiratory pressure (P_Emax) prior to, and 30 minutes and 60 minutes subsequent to NIV treatment (denoted by, respectively, the subscripted numbers 0, 30 and 60). NIV treatment was determined as being successful for 55 patients (the success group, for which individuals endotracheal intubation was avoided) and as being a failure for 31 patients (the failure group). APACHE II scores prior to treatment, P_Imax₃₀ (P_Imax 30 minutes subsequent to NIV), RR₃₀ (RR 30 minutes subsequent to NIV), and RR₆₀ (RR 60 minutes subsequent to NIV) were all significantly lower for the success group than for the failure group. The success group also had significantly better values for RR during the first 30 minutes of NIV treatment and for P_Emax during the first 60 minutes of NIV treatment compared to individuals from the failure group. Conclusion: APACHE II scores recorded prior to NIV treatment, P_Imax₃₀, RR₃₀, RR₆₀, as well as improvements to RR during the first 30 minutes of NIV treatment and to P_Emax during the first 60 minutes of NIV treatment were predictors of successful NIV treatment for patients suffering from acute respiratory failure. Such parameters may be helpful in selecting patients to receive NIV treatment and also for deciding when early termination of the treatment is appropriate.