The objective of the study was to quantitatively characterize peripheral tissue microvascular oxygenation during emergency department (ED) treatment of acute heart failure (HF).Methods
This prospective, observational study enrolled acutely decompensated HF patients presenting to an urban ED and stable, asymptomatic HF patients evaluated in an outpatient cardiology clinic. Stable, pre-ED treatment, and post-ED treatment microvascular oxygen extraction ratios (OERMs) were calculated, defined as SaO2 - StO2/0.8*SaO2, where SaO2 is pulse oximetry-derived arterial hemoglobin saturation and StO2 is the tissue hemoglobin oxygen saturation measured with differential absorption spectroscopy. The OERM measurements were analyzed using repeated-measures analysis of variance. Pulse oximetry, patient demographics, HF etiology, serum B-type natriuretic peptide, and hemoglobin were measured along with a visual analogue scale to assess patient baseline characteristics and response to ED treatment (P < .05 was considered significant for all testing).Results
The OERM for the stable HF group (n = 45) was 0.65 (SE = 0.07). The pre- and posttreatment OERMs for the ED HF group (n = 46) were 0.92 (SE = 0.07) and 0.75 (SE = 0.06), respectively. Whereas the pretreatment ED OERM was higher than the stable patient OERM (P = .001), the posttreatment ED OERM was not significantly different from the stable patient measurement (P = .271).Conclusions
Oxygen extraction in acute HF is significantly increased, but approaches values found in the stable HF population after ED treatment. The OERM may deserve closer examination as a possible goal-directed variable in the treatment of acute HF.