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Cardiac variability in critically ill adults: influence of sepsis
M Korach1, T Sharshar, I Jarrin
1Service de Réanimation Médicale, hôpital Raymond Poincaré, Faculté de médecine Paris ouest, Garches, France.
Objective:
To evaluate, in critically ill adults, factors associated with impaired sympathovagal balance.
Design:
One-month inception cohort study.
Setting:
Twenty-six-bed medical intensive care unit of a teaching hospital.
Patients:
Critically ill adults with an expected duration of intensive care unit stay of > or =48 hrs were enrolled. Patients with permanent arrhythmia or cardiac pacing were not included.
Interventions:
None.
Measurement And Main Results:
Sympathovagal balance was assessed on the day after intensive care unit admission by the low-frequency/high-frequency ratio obtained from spectral components of heart rate signal: overall variability, low frequency, and high frequency.
Results:
Forty-one patients, 13 with sepsis and 28 without sepsis, were assessed. Predictors of low-frequency/high-frequency ratio with the automatic interaction detection method were sepsis and age. Binary logit analysis adjusted for age showed that sepsis remained a strong and independent factor of a low-frequency/high-frequency ratio of <1.50, with an odds ratio of 3.63 (95% confidence interval, 1.47-9.01, p =.005). Use of mechanical ventilation, catecholamines, or sedation did not add any information. The use of the low-frequency/high-frequency ratio in diagnosing sepsis may be supported by a likelihood ratio for low frequency/high frequency <1 at 6.47.
Conclusions:
This work suggests that impaired cardiac variability and notably sympathovagal balance (i.e., a low-frequency/high-frequency ratio <1.0) may be a diagnostic test for sepsis.