The Importance of Plasma Renin Concentration in Intensive Care Patients with Circulatory Shock

Introduction: Renin is a hypoperfusion marker and a good index of renin-angiotensin-aldosterone system (RAAS) activity. The purpose of this study was to evaluate whether the plasma renin concentration (PRC) can represent a tissue perfusion marker for predicting mortality in patients with circulatory shock in intensive care. Method: This prospective study involved patients aged 18 or over in a tertiary intensive care unit (ICU). Sixty-nine patients were included, 37 of whom constituted the circulatory shock group, and 32 a non-shock control group. Blood specimens were collected to measure PRC levels. Combined tests including PRC, mottling scores, central venous saturation of oxygen (ScvO2), C-reactive protein (CRP), procalcitonin, and lactate were constituted. Results: The patients’ mean age was 61.5 (±16.4) years, and 58.0% (n=40) were men. Mean number of days in the ICU, ICU 28-day mortality, ICU 28-day dialysis requirements, ICU 28-day mechanical ventilation requirements, and adrenalin, noradrenalin, and terlipressin use were all higher in the patients with circulatory shock (p<0.05). Three-day survival following discharge from the ICU, Glasgow Coma Scale (GCS) scores, glomerular filtration rate (GFR), and ScvO2 levels were lower in the patients with circulatory shock (p<0.05). Sequential Organ Failure Assessment (SOFA) scores, Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, lactate, creatinine, CRP, procalcitonin, PRC, and mottling score values were higher in the circulatory shock group (p<0.05). Median overall survival time (OST) was higher in the non-circulatory shock patients (17.00 days; Wilcoxon χ^2=5.016; p=0.038). The increase in mottling (HR:1.64(1.15 – 2.33); p<0.01) and PRC (HR=1.01(1.00 – 1.02); p<0.05) levels and the decrease in GFR (HR=0.98(0.96 – 0.99); p<0.05) values in the ICU patients were correlated with length of survival (-2 Log Likelihood=59.237; Chi-square=17.105; df=3; p<0.001 (p=0.0007)). Combined test 1ᵈ (PRC, mottling, ScvO2, CRP, and procalcitonin), combined test 2ᵉ (PRC, lactate, and mottling), combined test 3ᶠ (PRC, lactate, mottling, CRP, and procalcitonin), and lactate emerged as indicators of 28-day mortality in patients with circulatory shock (p<0.05), although PRC did not represent such an indicator (p>0,05). Combined test 1ᵈ (PRC, ScvO2, CRP, and procalcitonin) and combined test 3ᶠ (PRC, lactate, CRP, and procalcitonin) emerged as markers of 28-day survival in patients without circulatory shock (p<0.05), but not combined test 2ᵉ (PRC and lactate), PRC, or lactate (p>0.05). Conclusion: A significant association was observed between PRC levels and survival. Combining PRC levels with lactate, mottling score, CRP, and procalcitonin results in better prediction of mortality than PRC alone. PRC levels have the potential for use as a good marker for patients with circulatory shock.