Hemodynamic response to low-flow acute supplemental oxygen in idiopathic pulmonary fibrosis and elderly healthy subjects.

Background: Hemodynamic response to supplemental oxygen in idiopathic pulmonary fibrosis (IPF) is still not well known.

Objective: To determine and compare the effect of low-flow acute supplemental oxygen on the hemodynamics of IPF patients and matched healthy subjects.

Methods: Descriptive and comparative study in 20 IPF-patients and 19 Control-subjects, (60-80 years old) breathing ambient air followed by acute nasal low-flow (3 L/min) supplemental oxygen. Non-invasive methods were used during the supine position to evaluate oxygen saturation, heart rate, stroke volume index, cardiac output index, total peripheral resistance and arterial blood pressure.

Results: Breathing ambient air, IPF (vs. Control) presented lower values in stroke volume index (38.7 [29.4-43.2] vs. 45.4 [38.4-50.9] mL•kg-1•m; p=0.009) and cardiac output index (2.484 [2.268 - 2.946] vs. 2.857 [2.628 - 3.054] L•min•m; p=0.028), with higher total peripheral resistance (1644 [1559-2076] vs. 1505 [1366-1784] dyne•s•cm; p=0.017). During supplemental oxygen (vs. ambient air), both groups increased oxygen saturation above 94% (p<0.001) while heart rate decreased about 6 to 8% (p<0.001); stroke volume index increased around 7% in the Control-group (p=0.004) but only 1% in the IPF-group (p=0.017). In addition, IPF showed increments in total peripheral resistance (1644 [1559-2076] vs. 1706 [1554-2278] dyne•s•cm; p=0.017) with subsequent decrements in cardiac output index (2.484 [2.268 - 2.946] vs. 2.362 [2.139 - 2.664] L•min•m; p<0.001).

Conclusion: Low-flow acute supplemental oxygen in IPF causes a meaningful decrement in cardiac output due to greater reduction in heart rate and increment in total peripheral resistance than matched healthy subjects. Knowing the hemodynamic profile of IPF patients may be helpful in determining their management with supplemental oxygen.