Effect of oxygen therapy on exercise performance in patients with cyanotic congenital heart disease: Randomized-controlled trial.

BACKGROUND

Patients with unrepaired cyanotic congenital heart disease (CHD) suffer from aggravated hypoxemia during exercise. We tested the hypothesis that supplemental oxygen improves exercise performance in these patients.

METHODS

In this randomized, sham-controlled, single-blind, cross-over trial cyanotic CHD-patients underwent four cycle exercise tests to exhaustion, while breathing either oxygen-enriched (FiO 0.50, oxygen) or ambient air (FiO 0.21, air) using incremental (IET) or constant work-rate (CWRET) exercise test protocols (75% of maximal work rate achieved under FiO 0.21). Pulmonary gas-exchange, electrocardiogram, arterial blood gases, oxygen saturation (SpO), cerebral and quadriceps muscle tissue oxygenation (CTO and QMTO) by near-infrared spectroscopy were measured.

RESULTS

We included seven patients with cyanotic CHD (4 Eisenmenger syndrome, 3 unrepaired cyanotic defects, 4 women) median (quartiles) age 36 (32;50) years, BMI 23 (20;26) kg/m and SpO at rest 87 (83;89) %. When comparing supplemental oxygen with air during exercise, maximal work-rate in IET increased from 76 (58;114) Watts to 83 (67;136) Watts, median difference 9 (0;22) W (p = 0.046) and CWRET-time increased from 412 s (325;490) to 468 s (415;553), median increase 56 (39;126) s (p = 0.018). In both IET and CWRET SpO was significantly higher and ventilatory equivalent for carbon dioxide significantly lower at end-exercise with oxygen compared to air, whereas CTO and QMTO did not significantly differ.

CONCLUSIONS

Patients with cyanotic CHD significantly improved their exercise performance, in terms of maximal work-rate and endurance time along with an improved arterial oxygenation and ventilatory efficiency with supplemental oxygen compared to air.