Oxygen inhalation decreases the central venous pressure in adult patients late after Fontan operations

Background

Elevated central venous pressure (CVP) and decreased arterial oxygen saturation (SaO₂) are the characteristics of patients after Fontan operations and determine morbidity and mortality in the long-term. Oxygen inhalation therapy theoretically increases SaO₂ and may decrease the elevated CVP in these patients. However, there is no previous study to support this hypothesis. This study aimed to determine the acute effects of oxygen inhalation on the hemodynamics of adult patients late after Fontan operations using cardiac catheterization.

Methods

This study enrolled 58 consecutive adult patients (median age, 30 years; female, n = 24) who had undergone Fontan operations. We assessed the hemodynamic changes during oxygen inhalation (2 L/min) with a nasal cannula in cardiac catheterization. We divided the studied patients into two groups according to the reduction in CVP during oxygen inhalation using the median value: responders (>2 mmHg) and non-responders (≤2 mmHg). Clinical characteristics of the responders to oxygen inhalation were investigated with uni- and multivariate analyses.

Results

SaO₂ increased from 93.3 % (91.3–94.5 %) to 97.5 % (95.2–98.4 %) (p < 0.001) and CVP decreased from 12 mmHg (11–14 mmHg) to 10 mmHg (9–12 mmHg) (p < 0.001) after oxygen inhalation. There was a weak but significant correlation between the increase in SaO₂ and the decrease in CVP (R = 0.29, p = 0.025). Pulmonary blood flow increased from 4.1 L/min (3.5–5.0 L/min) to 4.4 L/min (3.7–5.3 L/min) (p = 0.007), while systemic blood flow showed no significant changes. A multivariate analysis revealed that high baseline CVP was associated with a larger decrease in CVP (>2 mmHg) after oxygen inhalation.

Conclusions

Oxygen inhalation increased SaO₂ and decreased CVP, especially in patients with high baseline CVP. Further studies with home oxygen therapy are needed to investigate the long-term effects of oxygen inhalation in adult patients who underwent Fontan operations.