Effects of acute oxygen therapy on left ventricular diastolic filling in hypoxaemic cor pulmonale
David G. Kiely, Robert I. Cargill, Brian J. Lipworth

Background: Ventricular diastolic function is an important determinant of overall cardiovascular performance and is a sensitive marker of cardiac dysfunction. It is dependent on structural changes as well as functional abnormalities.

Patients and methods: 12 patients with hypoxaemic cor pulmonale 69(3) years with normal left ventricular systolic function were treated with 60% oxygen for 30 minutes. Indices of left ventricular diastolic function and pulmonary haemodynamics were measured using Doppler echocardiography.

Results: Treatment with 60% oxygen significantly increased oxygen saturation from 90 (0.9) to 98 (0.3) %. Hyperoxia compared to baseline had no significant effects on left ventricular diastolic filling parameters reflected by its lack of effect on left ventricular isovolumic relaxation time IVRT: 82 (4) vs 84 (3) ms and transmitral E/A ratio: 0.77 (0.06) vs 0.72 (0.05), respectively. Hyperoxia significantly reduced heart rate (HR): 70 (3) vs 74 (2) bpm, mean pulmonary artery pressure (MPAP): 27 (1) vs 32 (2) mmHg, total pulmonary vascular resistance (PVR): 376 (21) vs 432 (18) dyne.s.cm-5 but had no significant effects on either cardiac output (CO): 5.68 (0.19) vs 5.88 (0.14) l/min or mean arterial blood pressure (MAP): 104 (5) vs 103 (4) mmHg, respectively compared to baseline. 

Conclusions: Although short term administration of high flow oxygen has beneficial pulmonary haemodynamic effects it appears to have no significant effects on left ventricular diastolic filling. This suggests that abnormalities other than myocyte hypoxaemia are responsible for impairment of left ventricular diastolic filling in established hypoxaemic cor pulmonale and that oxygen therapy when given acutely does not improve myocardial relaxation.

Keywords: Cor pulmonale, diastolic function, oxygen

Applied Cardiopulmonary Pathophysiology 9: 27-31, 2000

David G. Kiely, M.D.
Papworth Hospital
Cambridge University Teaching Hospitals Trust
Papworth Everard
Cambridge CB3 8RE, UK
Phone: 44-1480-830541
Fax: 44-1480-830650