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Linear and nonlinear analysis of hemodynamic signals during sepsis and septic shock
D Toweill1, K Sonnenthal, B Kimberly
1Department of Pediatrics, Oregon Health Sciences University, Portland, USA.
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, indicating uncoupling of the autonomic and cardiovascular systems.
Design:
Prospective case series.
Setting:
Pediatric intensive care unit in a tertiary care children's hospital.
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 nonlinear 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] bpm2; p = .03) and high-frequency HR power (2.18 +/- 0.14 vs. 2.79 +/- 0.23 bpm2; p = .04) and increased detrended fluctuation analysis scaling exponent (1.22 +/- 0.06 vs. 1.00 +/- 0.07 bpm2; p = .02) in sepsis vs. shock patients, respectively. Compared with sepsis or shock, recovery was associated with increases in low-frequency (3.61 +/- 0.15 vs. 3.05 +/- 0.19 bpm2; 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 cardiovascular 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.