Linear and nonlinear analysis of hemodynamic signals during sepsis and septic shock

Objective: Neuroautonomic modulation of heart rate (HR) and blood pressure were assessed in sepsis or septic shock. We hypothesized that these metrics would be diminished in pediatric patients with sepsis and septic shock, in dicating uncoupling of the autonomic and cardiovascular systems. Design: Prospective case series. Setting: Pediatric intensive care unit in a tertiary care children's hospit al. Patients: Thirty pediatric patients with sepsis or septic shock. Interventions: None. Measures and Main Results:Metrics used included power spectral analysis, a linear frequency domain measure, and detrended fluctuation analysis, a nonl inear technique that assesses the degree of long-range correlation in HR or blood pressure. We found decreased low-frequency (2.68 +/- 0.24 vs, 3.37 /- 0.17 [SEM] bpm(2); p = .03) and high-frequency HR power (2.18 +/- 0.14 v s. 2.79 +/- 0.23 bpm(2); p = .04) and increased detrended fluctuation analy sis scaling exponent (1.22 +/- 0.06 vs, 1.00 +/- 0.07 bpm(2); p = .02) in s epsis vs. shock patients, respectively. Compared with sepsis or shock, reco very was associated with increases in low-frequency (3.61 +/- 0.15 vs. 3.05 +/- 0.19 bpm(2); p < .0001) and high-frequency HR power (3.11 +/- 0.15 vs. 2.50 +/- 0.22 bpm2; p < .0001). Conclusions: We conclude that uncoupling of the autonomic and cardiovascula r systems occurs over both short- and long-range time scales during sepsis, and the degree of uncoupling may help differentiate between sepsis, septic shock,and recovery states.