Autonomic dysfunction predicts both 1- and 2-month mortality in middle-aged patients with multiple organ dysfunction syndrome*

OBJECTIVE: Multiple organ dysfunction syndrome (MODS) is a disease entity that carries a high mortality rate. It is characterized by a sequential failure of several organ systems after a trigger event, most commonly sepsis. There is increasing evidence that autonomic dysfunction may substantially contribute to the development of MODS. We recently characterized the spectrum of autonomic dysfunction by using heart rate variability in critically ill MODS patients and were able to show that autonomic dysfunction predicts 28-day mortality in MODS. The aim of the present study was evaluate whether autonomic dysfunction is also a predictor of 180-day and 365-day mortalities. DESIGN: Prospective cohort study. SETTING: Twelve-bed medical intensive care unit in a university center. PATIENTS: Ninety consecutively admitted score-defined MODS patients. INTERVENTIONS: We assessed heart rate variability as a marker of autonomic dysfunction. The patients were followed for 180- and 365-day mortalities. MEASUREMENTS AND MAIN RESULTS: We prospectively used the heart rate variability variable lnVLF, which predicted 28-day mortality best in the entire cohort of patients, for analysis of longer term mortality. The variable lnVLF was found to be useful for risk prediction for about 60 days, and then the survival curves became nearly parallel. CONCLUSIONS: Autonomic function of critically ill MODS patients is blunted, and this attenuation has prognostic implications not merely concerning 28-day mortality but also concerning longer term (about 2-month) mortality.