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Principal Investigator(s)


Anna Fazekas



SEVA - Improving Safety of Sedation Practice and Critical Illness Prognostication

In the Intensive Care Unit (ICU) critically ill patients require sedatives and painkillers to tolerate life support. Concerns regarding patient suffering and safety and lack of criteria to guide safe decrease in sedation lead to the widespread problem of over-sedation, which causes real harm to patients and extends their stay in the ICU.  The focus of this proposal is on improving safety of sedation practices in critically ill patients, by uncovering hidden information contained within the patterns of variation of heart and respiratory rate, in order to determine if it is safe to markedly reduce sedation. We and others have shown that both heart and respiratory rate variability (HRV &RRV) are reduced (i.e. more regular, less adaptable rhythms) in states of critical illness, and variability is also reduced by sedation. We have discovered in our pilot study that monitoring variability during the time when sedation is interrupted uncovers the “true” variability relating to the underlying level of illness. Our project objectives are to evaluate heart rate and respiratory rate variability (HRV and RRV) during SV as a means to: 1) assist in decision making regarding the patient’s need for further sedation; 2) objectively quantify underlying severity of illness and its alteration over time; 3) determine how different types of sedatives alter variability; and 4) identify patterns of altered variation that may help identify pain/agitation/delirium and patients who are over-sedated. A 33-patient single centre pilot study of continuous HRV and RRV monitoring in critically ill patients revealed that patients with low cumulative organ failure scores (MODS<2) had a marked restoration in both HRV and RRV upon stopping sedation, whereas patients with high organ failure (MODS>4) had minimal increase or even a worsening of variability, in particular RRV. Thus, change in variability inversely correlated with degree of organ failure. In addition, the reduction in RRV in patients with elevated organ failure potentially indicated that cessation of sedation in these patients may not have been beneficial. We interpret these results as indicating technical feasibility as well providing support for further investigation.

Current Status: Ongoing - Pilot Study in press in Crit Care Med., applied for CIHR funding Sept 2012

Overall Theme:

Development, Clinical Evaluation & Understanding of Multiorgan Variability Monitoring

Overall Objectives:

• Pioneer the development of software to perform multiorgan variability monitoring
• Definition of physiologic variability at rest and during exercise
• Characterize patterns of pathologic variability at risk for or with existing critically illness
• Define a systematic approach to selecting biologic variables for dynamical analysis
• Understand patterns of alteration of inter-organ variability alteration in critical illness
• Understand temporal evolution of multiorgan variability compared to clinical events
• Define relationship between multiorgan variability and physiologic measures
• Evaluate the role of variability monitoring to improve clinical decision making


 Yoanna Skrobic, S angeeta Mehta, John Marshall, Claudio Martin, Lauralyn McIntyre , Dean Fergusson

Participating Centers

Ottawa General, Ottawa Civic, Mt Sinai Hospital (Sangeeta Mehta’s site), St Michael’s Hospital (John Marshall’s site), London Health Sciences Center (Claudio Martin’s site)