Autonomic dysfunction in ICU-acquired weakness: a prospective observational pilot study
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Intensive care unit-acquired weakness (ICU-AW) is a frequent complication of critical illness. It is unknown if patients with ICU-AW also have autonomic dysfunction, another frequent neurological complication of critical illness. We hypothesized that patients who develop ICU-AW also develop autonomic dysfunction. Furthermore, we hypothesized that patients with ICU-AW are more prone to develop autonomic dysfunction compared to patients without ICU-AW.
This was an observational cohort study of patients newly admitted to the ICU. Autonomic dysfunction was measured daily using heart rate variability (HRV) to a maximum of 15 days after admission. ICU-AW was diagnosed using the Medical Research Council score. Abnormal HRV was defined using age-matched reference values. The association between ICU-AW and HRV was analyzed using linear mixed effects models.
We included 83 patients, 15 (18 %) of whom were diagnosed with ICU-AW. Of 279 HRV measurements, 204 could be analyzed. Abnormal HRV was found in all critically ill patients irrespective of the presence of ICU-AW (ICU-AW 100 % (IQR 71–100) vs. no ICU-AW 100 % (IQR 40–100); p = 0.40). Mechanical ventilation, sedation, norepinephrine, heart rate, and HRV artifacts were identified as confounders for HRV. ICU-AW was not associated with HRV.
Abnormal HRV is frequent in critically ill patients, both with and without ICU-AW. It is unlikely that patients with ICU-AW are more prone to develop abnormal HRV. However, we found that abnormal HRV may not be an accurate indicator of autonomic dysfunction because of confounders.
KeywordsIntensive care unit-acquired weakness Autonomic dysfunction Heart rate variability Critical illness
The authors thank G. Sussenbach for his work on the development of the HRV recording equipment and software. This research was performed within the framework of CTMM, the Center for Translational Molecular Medicine (www.ctmm.nl), project MARS (grant 04I-201). Dr. L. Wieske is supported by a personal grant from the Netherlands Organization for Health Research and Development (ZonMw–AGIKO grant [project number 40-00703-98-11636]).
Conflicts of interest
The authors declare that they have no conflict of interest.
- 21.Wieske L, Kiszer ER, Schultz MJ et al (2012) Examination of cardiovascular and peripheral autonomic function in the ICU: a pilot study. J Neurol. doi:10.1007/s00415-012-6818-6