RESUMEN
BACKGROUND: Emphasis in therapy of human septic shock is shifting towards reliable end points and predictors of survival. Rationale is to study whether the evolution of cardiovascular reactivity in view of the administered doses of norepinephrine is an early predictor of in-hospital survival and to determine the optimal threshold of norepinephrine therapy and its consequences on renal function. METHODS: Observational study of a prospective cohort of patients in septic shock, hospitalized in intensive care unit at least 24 hours before requiring norepinephrine. Excluded were patients requiring <72 hours of continuous norepinephrine (16 patients) or who received corticosteroids. Hemodynamic parameters (heart rate, blood pressure, urinary output, and temperature) were continuously monitored. RESULTS: Of 68 patients, 45 survived [intensive care unit stay of 24 (12-36) days, hospital stay of 36 (27-66) days], and 23 died 5 (3-10) days after septic shock onset and norepinephrine treatment. Multivariate analysis revealed four independent positive predictive factors of short-term (10 days) outcome: Simplified Acute Physiology Score (SAPS) II <50 [odds ratio (OR) 6.4, 95% confidence interval (95% CI) 1.3-30.7, p < 0.011], and on day 3 Logistic Organ Dysfunction System (LODS) score <6 (OR 29.1, 95% CI 2.7-314.3, p = 0.0056), norepinephrine concentration <0.5 mug/kg/min (OR 17.6, 95% CI 2.2-142.0, p < 0.0007), diastolic arterial pressure >50 mm Hg (OR 24.8, 95% CI 2.9-215.9, p < 0.004), but not systolic arterial pressure. CONCLUSIONS: Septic shock survival increases when dose of 0.5 mug/kg/min of norepinephrine continuously improves vascular tone within the first 48 hours, or when diastolic arterial pressure (>50 mm Hg) is restored. Norepinephrine has beneficial effects on renal function. Predictive value of LODS score on day 3 is demonstrated, while SAPS II is confirmed as the only reliable predictive factor in first 24 hours.