Uncontrolled oxygen administration and respiratory failure in acute asthma.
OBJECTIVE
To determine if 100% oxygen administration adversely influences gas exchange in acutely ill asthmatic subjects.


METHODS
Prospective preinterventional and postinterventional comparison.


METHODS
University hospital emergency department.


METHODS
Thirty-seven asthmatic subjects seeking care for symptomatic exacerbations.


METHODS
Twenty minutes of 100% oxygen administration by face mask.


RESULTS
Arterial blood gases and FEV(1) were measured before and during the last minute of oxygen administration. On presentation, the subjects had moderately severe airway obstruction (FEV(1), 49.1 +/- 3.6% of predicted); hypocarbia (PaCO(2), 36.8 +/- 1.1 mm Hg); hypoxemia (PaO(2), 70.2 +/- 2.5 mm Hg); and respiratory alkalosis (pH, 7.43 +/- 0.01). During oxygen breathing, 25 patients (67.6%) experienced elevations in PaCO(2) ranging from 1 to 10 mm Hg (mean, 4.1 +/- 0.6 mm Hg; p = 0.0003). The increase was considered to be a physiologic manifestation of the Haldane effect (ie, < or = 2 mm Hg) in 10 subjects, but in the remaining 15 subjects (40.5% of the total studied), the elevation represented worsening gas exchange. In seven of these patients (46.7%), hypercapnic respiratory failure developed (PaCO(2) before oxygen, 39.6 +/- 0.6; during oxygen, 44.7 +/- 0.7 mm Hg; p = 0.005), and in six patients (40%), it worsened (PaCO(2) before oxygen, 46.8 +/- 1.9; during oxygen, 52.0 +/- 3.1 mm Hg; p = 0.03). In general, the tendency toward hypercarbia was the greatest in the participants with the most severe airway obstructions.


CONCLUSIONS
Our data demonstrate that the administration of 100% oxygen to acutely ill asthmatics may adversely influence carbon dioxide elimination.
Chien
J W
JW
Division of Pulmonary and Critical Care Medicine of University Hospitals of Cleveland, and the Department of Medicine of Case Western Reserve University School of Medicine, Cleveland, OH 44106-5067, USA.
Ciufo
R
R
Novak
R
R
Skowronski
M
M
Nelson
J
J
Coreno
A
A
McFadden
E R
ER
D000208:Acute Disease; D000328:Adult; D000403:Airway Resistance / Q000502:physiology; D001249:Asthma / Q000503:physiopathology / Q000628:therapy*; D001784:Blood Gas Analysis; D004636:Emergency Service, Hospital; D005260:Female; D005541:Forced Expiratory Volume / Q000502:physiology; D006801:Humans; D006935:Hypercapnia / Q000209:etiology / Q000503:physiopathology; D008173:Lung Diseases, Obstructive / Q000503:physiopathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D010102:Oxygen Inhalation Therapy / Q000009:adverse effects*; D011446:Prospective Studies; D011659:Pulmonary Gas Exchange; D012131:Respiratory Insufficiency / Q000209:etiology* / Q000503:physiopathology; D012307:Risk Factors