Oxygen therapy improves cardiac index and pulmonary vascular resistance in patients with pulmonary hypertension.
OBJECTIVE
We tested the hypothesis that breathing 100% oxygen could result in selective pulmonary vasodilatation in patients with pulmonary hypertension, including those patients who would not meet current Health Care Finance Administration guidelines for long-term oxygen therapy.


METHODS
From 1996 to 1999, 23 adult patients (mean +/- SEM age, 51 +/- 4 years) with pulmonary arterial hypertension without left-heart failure underwent cardiac catheterization in a university teaching hospital while breathing air and then 100% oxygen.


RESULTS
Treatment with 100% oxygen increased arterial oxygen saturation (91 +/- 1% to 99 +/- 0.1%, p < 0.05) and PaO(2) (64 +/- 3 to 309 +/- 28 mm Hg, p < 0.05). Treatment with 100% oxygen also decreased mean pulmonary artery pressure (56 +/- 3 to 53 +/- 2 mm Hg, p < 0.05) and increased cardiac index (2.1 +/- 0.1 to 2.5 +/- 0.2 L/min/m(2), p < 0.05). Calculated mean pulmonary vascular resistance (PVR) decreased from 14.1 +/- 1.4 to 10.6 +/- 1.0 Wood units (p < 0.05). Vasodilatation with 100% oxygen occurred preferentially in the pulmonary circulation (PVR/systemic vascular resistance, 0.53 +/- 0.04 to 0.48 +/- 0.03; p < 0.05). The magnitude of the PVR response to oxygen therapy was correlated only with decreasing patient age (r = 0.45, p < 0.05).


CONCLUSIONS
Treatment with 100% oxygen is a selective pulmonary vasodilator in patients with pulmonary hypertension, regardless of primary diagnosis, baseline oxygenation, or right ventricular function. Development of disease-specific oxygen prescription guidelines warrants consideration.
Roberts
D H
DH
Pulmonary and Critical Care Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA.
Lepore
J J
JJ
Maroo
A
A
Semigran
M J
MJ
Ginns
L C
LC
D000328:Adult; D000368:Aged; D001794:Blood Pressure; D002302:Cardiac Output; D005260:Female; D006439:Hemodynamics; D006801:Humans; D006976:Hypertension, Pulmonary / Q000097:blood / Q000503:physiopathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010102:Oxygen Inhalation Therapy; D011651:Pulmonary Artery / Q000503:physiopathology; D014655:Vascular Resistance; D014664:Vasodilation
D010100:Oxygen