Study objectives: Bilevel pressure ventilation
has had proven success in the treatment of acute respiratory failure
(ARF). The purpose of this study was to identify patient
characteristics early in the course of acute illness that can predict
the successful use of bilevel pressure ventilation.
Methods: Ventilatory assistance using a ventilatory support
system (BiPAP model ST-D; Respironics; Murrysville, PA) was considered
a treatment option for stable patients with ARF. The system was
titrated to patient comfort. Once stable settings had been achieved for
30 min, a posttrial arterial blood gas (ABG) measurement was
obtained. Patient charts were reviewed for pretrial and posttrial ABG
levels, along with demographics, APACHE (acute physiology and chronic
health evaluation) II score, Glasgow Coma Scale (GCS), and length of
stay (LOS) data.
Results: Bilevel pressure
ventilation trials were performed on 58 patients. In 43 patients
(74.1%), the trials were successful. Of the 15 patients (25.9%) in
whom the trials were not successful, 13 patients required intubation.
The pretrial ABG levels did not predict success, as there were no
significant differences between the success and failure groups for pH
and Paco2, respectively: 7.26 vs 7.26 mm Hg and
75.3 vs 72.8 mm Hg. After 30 min, posttrial ABG levels for pH and
Paco2 predicted successful avoidance of
intubation: 7.34 vs 7.27 mm Hg (p < 0.002) and 61.9 vs 73.0 mm Hg
(p < 0.04), respectively. There were no significant differences
between the success and failure groups in age, gender, GCS, or APACHE
II. There were differences between the success and failure
groups for LOS data (ventilator days, ICU days, and hospital days): 1.8
vs 10.4 days (p < 0.01), 4.2 vs 12.3 days (p < 0.02), and 7.5 vs
15.6 days (p < 0.02), respectively.
Successful treatment with bilevel pressure ventilation could not be
predicted by pretrial data (including pH and
Paco2) obtained in the emergency department;
however, a successful outcome could be determined quickly with a 30-min
trial. Successful treatment with bilevel pressure ventilation
significantly reduced LOS data.
Our inability to predict success based on initial data supports the use
of bilevel pressure ventilation trials for all stable patients with
ARF. If the patient’s condition fails to improve within 30 min,
intubation amd mechanical ventilation is