Intradialytic hypertension is associated with low intradialytic arterial oxygen saturation.

Background. The pathophysiology of a paradoxical systolic blood pressure (SBP) rise during hemodialysis (HD) is not yet fully understood. Recent research indicated that 10% of chronic HD patients suffer from prolonged intradialytic hypoxemia. Since hypoxemia induces a sympathetic response we entertained the hypothesis that peridialytic SBP change is associated with arterial oxygen saturation (SaO₂). Methods. We retrospectively analyzed intradialytic SaO₂ and peridialytic SBP change in chronic HD patients with arteriovenous vascular access. Patients were followed for 6months. We defined persistent intradialytic hypertension (piHTN) as average peridialytic SBP increase ≥10mmHg over 6months. Linear mixed effects (LME) models were used to explore associations between peridialytic SBP change and intradialytic SaO₂ in univariate and adjusted analyses. Results. We assessed 982 patients (29 872 HD treatments; 59% males; 53% whites). Pre-dialysis SBP was 146.7±26.5mmHg and decreased on average by 10.1#177;24.5mmHg. Fifty-three (5.7%) patients had piHTN. piHTN patients had lower intradialytic SaO₂, body weight and interdialytic weight gain. LME models revealed that with every percentage point lower mean SaO₂, the peridialytic SBP change increased by 0.46mmHg (P<0.001). This finding was corroborated in multivariate analyses. Conclusion. We observed an inverse relationship between intradialytic SaO₂ and the blood pressure response to HD. These findings support the notion that hypoxemia activates mechanisms that partially blunt the intradialytic blood pressure decline, possibly by sympathetic activation and endothelin-1 secretion. To further explore that hypothesis, specifically designed prospective studies are required. [ABSTRACT FROM AUTHOR]