The Science Journal of the American Association for Respiratory Care

2001 OPEN FORUM Abstracts

Non-invasive positive pressure ventilation and oxygenation: a cautionary tale

Lahsha Welch,RRT, RosaWoodrum, RRT, Wayne Wallace, BA, RRT, DavidSuh, MD,& Bhanu Pandiri, MD Kaiser Permanente West Los AngelesMedical Center, Los Angeles, CA

BACKGROUND: KaiserPermanente?s West Los Angeles Medical Center is an acute care hospital servingthe HMO?s members on the west side of Los Angeles. In 1997, the medical centerinstituted an aggressive non-invasive ventilator program with the goal thatbetween 10-20% of all mechanical ventilation would be delivered non-invasively.Patients were treated with non-invasive ventilatory (NIPPV) techniques primarilyin the hospital?s telemetry unit and ICU, although some patients were initiatedin the Emergency Department. The equipment used during the study was the Respironics?ST-D 20 and 30 series non-invasive ventilators.

Methods: 71 patientswere placed on NIPPV and arterial blood gases were obtained immediately priorto initiation of NIPPV and within one hour after therapy had commenced. A pairedStudent?s T-test was used to evaluate the results.

Results: Thefindings are summarized in the table below (pH, PaCO2, and PaO2are mean values):

pH7.287.35< .0001
PaCO272.559.3< .0001


EXPERIENCE: Asexpected, the patient?s pH rose and the paCO2 fell significantlyin response to therapy. However, paO2 also dropped significantlywhile receiving NIPPV. The rate of success of NIPPV (patient?s respiratory failuremanaged successfully without intubation) for this series of patients was stilla robust 80.3%.

Conclusions: Thisis a cautionary tale alerting clinicians to exercise extra vigilance to ensureadequate patient oxygenation during NIPPV. Older BiPAP? units that deliver oxygenvia an external oxygen flow meter ?bleed-in? to the patient circuit or maskmay not be capable of meeting the patient?s oxygen requirements. It is hopedthat newer units with built-in air/oxygen blenders will eliminate this dilemma.



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