Inappropriate sympathetic activation at onset of septic shock: a spectral analysis approach.

The autonomic cardiovascular control was investigated in 10 patients with septic shock, 10 patients with sepsis syndrome, and six tilted healthy subjects. Overall variability, high- and low-frequency components (AUC, HF, and LF, beats/min2/Hz or mm Hg2/Hz) from heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressures spectra were obtained from 5-min recordings. LFHR/HFHR and the square root of LFSBP/LFHR ( α ) were used as indices of sympathovagal interaction and baroreflex control of the heart, respectively. Compared with tilted control subjects and patients with sepsis syndrome, septic shock is characterized by reduction in: (1) HR variability, i.e., decreased AUCHR (p = 0.007), LFHR (p = 0.002), and LFHR/HFHR (p = 0.0002); (2) DBP variability, i.e., decreased AUCDBP (p = 0.003) and LFDBP (p = 0.001), (3) α (p = 0.003). In septic shock, LFHR/HFHR, α , and LFDBP correlated with mean blood pressure (r = 0.67, p = 0.04, r = 0.64, p = 0.03, and r = 0.88, p = 0.0008, respectively), and with plasma...