Journal of Critical Care
Volume 27, Issue 2 , Pages 218.e9-218.e20, April 2012

Feasibility of continuous multiorgan variability analysis in the intensive care unit☆☆☆

  • Beverly Bradley, MASc

      Affiliations

    • Ottawa Hospital Research Institute, Ottawa, Ontario, Canada, K1H 8L6
    • ,
  • Geoffrey C. Green, MASc

      Affiliations

    • Ottawa Hospital Research Institute, Ottawa, Ontario, Canada, K1H 8L6
    • ,
  • Izmail Batkin, PhD

      Affiliations

    • Ottawa Hospital Research Institute, Ottawa, Ontario, Canada, K1H 8L6
    • ,
  • Andrew J.E. Seely, MD, PhD

      Affiliations

    • Ottawa Hospital Research Institute, Ottawa, Ontario, Canada, K1H 8L6
    • Division of Thoracic Surgery, University of Ottawa, Ottawa, Ontario, Canada, K1H 8L6
    • Department of Critical Care Medicine, University of Ottawa, Ottawa, Ontario, Canada, K1H 8L6
    • Corresponding Author InformationCorresponding author. Divisions of Thoracic Surgery and Critical Care Medicine, Ottawa Hospital-General Campus, Box 708, Ottawa, Ontario, Canada K1H 8L6. Tel.: +1 613 737 8899x74892; fax: +1 613 737 8668.

published online 15 December 2011.

Abstract 

Purpose

The aim of the study was to evaluate the feasibility of continuous heart and respiratory rate variability (HRV and RRV, respectively) monitoring in critically ill patients derived from electrocardiogram (ECG) and end-tidal capnography (etCO2) waveforms.

Methods

Thirty-four patients (age, 56.5 ± 15.9 years; Acute Physiology and Chronic Health Evaluation II score, 22.8 ± 6.7) underwent continuous recording of ECG and etCO2 waveforms from intensive care unit admission and intubation to discharge or maximum of 14 days. Overlapping 5-minute windows were analyzed with a wide range of variability measures (time, frequency, entropy, and scale-invariant and nonlinear domains). Waveform data quality, presence of disconnections and arrhythmias, quality of beat and breath detection, and subsequent variability computations were evaluated.

Results

Patients were enrolled for 11.0 ± 3.6 days. The proportion of missing waveform data among all patients was (median [interquartile range, maximum]) 2.9% (1.3%-9.7%, 36.4%) for ECG and 3.1% (1.1%-11.4%, 84.5%) for etCO2. Heart rate variability data loss (ie, proportion of windows removed) was 1.3% (1.0%-2.1%, 5.9%) due to disconnection, 0.6% (0.1%-3.9%, 39.5%) due to atrial fibrillation, and 6.6% (1.4%-17.9%, 89.0%) due to data cleaning. Respiratory rate variability data loss was 7.3% (2.9%-11.6%, 47.7%) due to disconnection (or apnea) and 5.5% (2.9%-8.4%, 56.4%) due to cleaning. Continuous individualized multiorgan variability analysis processing resulted in HRV and RRV computations for 81.2% ± 25.0% and 87.5% ± 11.9% of available ECG and etCO2 waveform data, respectively.

Conclusions

The quality of continuously recorded ECG and etCO2 waveforms in critically ill patients is adequate for subsequent continuous variability monitoring in this pilot study. The clinical utility of continuous variability analysis merits further investigation.

Keywords: Heart rate variability, Respiratory rate variability, Continuous waveform monitoring, Multiorgan, Data loss, Data quality

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☆ Institution at which the work was done: Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.

☆☆ Competing interests: Andrew JE Seely founded Therapeutic Monitoring Systems (TMS), Inc. to commercialize patented Continuous Individualized Multiorgan Variability Analysis (CIMVA) technology with the objective of delivering variability-directed clinical decision support to improve quality and efficiency of care. All the other authors have no conflicts of interest to disclose.

PII: S0883-9441(11)00442-4

doi:10.1016/j.jcrc.2011.09.009

Journal of Critical Care
Volume 27, Issue 2 , Pages 218.e9-218.e20, April 2012

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