Abstract P209: Serum B-Type Natriuretic Peptide Measurement Correlates with Microvascular Tissue Oxygenation
Introduction: When patients with heart failure (HF) are resuscitated from trauma or cardiac arrest, the underlying state of chronic microvascular hypoperfusion associated with HF poses additional management challenges. Tissue oxygenation assessment yields a quantitative measure that may allow a better understanding of HF on a microvascular level. B-type natriuretic protein (BNP) measurement, a currently used HF assessor, has not previously been correlated with microvascular oxygenation.
Hypothesis: We hypothesize a microvascular oxygen extraction ratio (OERM) measured in acutely decompensated HF subjects will have poor correlation with BNP.
Methods: Subjects with acutely decompensated HF presenting to a tertiary care ED had pulse oximetry (SaO2), mean arterial pressure, serum hemoglobin, BNP and demographics recorded upon presentation. The hypothenar cutaneous tissue oxygenation saturation (StO2) was measured with near-infrared spectroscopy and used to calculate OERM using the formula, OERM=0.8 × ([SaO2 − StO2]/SaO2). Linear regression analysis was used to determine if a relationship exists between OERM and BNP, and to detect a significant correlation using a one-sided test, a sample size of 28 subjects would be required for 90% power (significant p-value <0.05). Results were reported as means with 95% confidence intervals.
Results: Twenty nine patients (51.7% female) were enrolled, with a mean age of 63.0 years (58.2 to 67.7), a mean MAP of 111.9 mmHg (99.7–124.1), a mean SaO2 of 96.2% (94.6–97.8), and a mean hemoglobin of 12.3 g/dL (11.5–13.0); 93% were African American, with 3% white and 3% Hispanic. The mean BNP level was 1806.5 pg/mL (1204.2–2408.8) and the mean OERM was 0.39 (0.36–0.43). The test of linear correlation determined there was a significant positive linear correlation between BNP and OERM (r=0.23, p=0.0078).
Conclusions: Linear regression analysis demonstrated a significant relationship between OERM and serum BNP. That a global parameter like BNP correlates with a microvascular parameter such as the OERM was unexpected and raises the question if BNP impacts microvascular oxygenation. Further investigation is required to delineate this relationship which may have implications for the acute resuscitation of HF patients.