The Science Journal of the American Association for Respiratory Care

2003 OPEN FORUM Abstracts

EFFECT OF NITROGEN WASHOUT STUDIES USING 100% O2 ON PATIENTS HAVING SEVERE COPD

Author: John W. Earl RRT, BS
Director Respiratory Care Service (retired)
VA Medical Center, White River Jct. Vermont 05009
 
Objective To investigate if patients with evidence of severe chronic obstructive lung disease (COPD) have a reduction in ventilation and/or become mentally impaired when administered 100% oxygen (O2) while performing a nitrogen (N2) washout study over a seven-minute period.

Methods:
 Fifty patients were tested using a Sensor Medics VMax system ® calibrated per manufacturers recommendations. Nitrogen washout is accomplished using a closed system that delivers 100% O2. Patients chosen for this investigation were those who required greater than seven minutes to complete their study. A seven-minute washout time indicates significant air trapping and strong evidence for severe COPD. At no time was there any coaching or encouragement provided except when it was suspected that a leak was occurring at mouthpiece. SpO2 levels were continuously monitored. Twenty-eight of the patients studied had PaCO2 levels above 50 mmHg.

RESULTS:
There was no reduction in ventilation per evidence supplied by graphical display and observation. All patients remained cognizant and conversant following each study. Patient Spo2 levels at start of study varied from 72% to 93% on room air. All had 100% SpO2 following study.

Conclusions:
 This study provides evidence that abundant amounts of oxygen can be provided to severe COPD patients with no consequence over a seven-minute period.

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