Consciousness induced during cardiopulmonary resuscitation: An observational study.
Cardiopulmonary resuscitation-induced consciousness (CPRIC) is a phenomenon that has been described in only a handful of case reports. In this study, we aimed to describe CPRIC in out-of-hospital cardiac arrest (OHCA) patients and determine its association with survival outcomes.



Retrospective study of registry-based data from Victoria, Australia between January 2008 and December 2014. Adult OHCA patients treated by emergency medical services (EMS) were included. Multivariable logistic regression was used to determine the association between CPRIC and survival to hospital discharge.



There were 112 (0.7%) cases of CPRIC among 16,558 EMS attempted resuscitations, increasing in frequency from 0.3% in 2008 to 0.9% in 2014 (p=0.004). Levels of consciousness consisted of spontaneous eye opening (20.5%), jaw tone (20.5%), speech (29.5%) and/or body movement (87.5%). CPRIC was independently associated with an increased odds of survival to hospital discharge in unwitnessed/bystander witnessed events (OR 2.09, 95% CI: 1.14, 3.81; p=0.02) but not in EMS witnessed events (OR 0.98, 95% CI: 0.49, 1.96; p=0.96). Forty-two (37.5%) patients with CPRIC received treatment with one or more of midazolam (35.7%), opiates (5.4%) or muscle relaxants (3.6%). When stratified by use of these medications, CPRIC in unwitnessed/bystander witnessed patients was associated with improved odds of survival to hospital discharge if medications were not given (OR 3.92, 95% CI: 1.66, 9.28; p=0.002), but did not influence survival if these medications were given (OR 0.97, 95% CI: 0.37, 2.57; p=0.97).



Although CPRIC is uncommon, its occurrence is increasing and may be associated with improved outcomes. The appropriate management of CPRIC requires further evaluation.
Department of Community Emergency Health and Paramedic Practice, Monash University, Frankston, Victoria, Australia; Emergency & Trauma Centre, The Alfred Hospital, Melbourne, Victoria, Australia; National Trauma Research Institute, The Alfred Hospital, Melbourne, Victoria, Australia.
Alexander
A
Olaussen
Department of Community Emergency Health and Paramedic Practice, Monash University, Frankston, Victoria, Australia; Department of Research and Evaluation, Ambulance Victoria, Doncaster, Victoria, Australia; Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia; Department of Emergency Operations, Ambulance Victoria, Doncaster, Victoria, Australia. Electronic address: ziad.nehme@ambulance.vic.gov.au.
Ziad
Z
Nehme
Department of Community Emergency Health and Paramedic Practice, Monash University, Frankston, Victoria, Australia; Department of Emergency Operations, Ambulance Victoria, Doncaster, Victoria, Australia.
Matthew
M
Shepherd
Department of Community Emergency Health and Paramedic Practice, Monash University, Frankston, Victoria, Australia; Emergency & Trauma Centre, The Alfred Hospital, Melbourne, Victoria, Australia; Department of Emergency Operations, Ambulance Victoria, Doncaster, Victoria, Australia; College of Health and Biomedicine, Victoria University, Melbourne, Victoria, Australia.
Paul A
PA
Jennings
Department of Research and Evaluation, Ambulance Victoria, Doncaster, Victoria, Australia; Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia.
Stephen
S
Bernard
Emergency & Trauma Centre, The Alfred Hospital, Melbourne, Victoria, Australia; National Trauma Research Institute, The Alfred Hospital, Melbourne, Victoria, Australia; Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia.
Biswadev
B
Mitra
Department of Community Emergency Health and Paramedic Practice, Monash University, Frankston, Victoria, Australia; Department of Research and Evaluation, Ambulance Victoria, Doncaster, Victoria, Australia; Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Victoria, Australia; Discipline of Emergency Medicine, School of Primary, Aboriginal and Rural Health Care, University of Western Australia, Crawley, Western Australia, Australia.
Karen
K
Smith
D000368:Aged; D001315:Australia / Q000453:epidemiology; D016887:Cardiopulmonary Resuscitation / Q000009:adverse effects / Q000379:methods / Q000706:statistics & numerical data; D003243:Consciousness / Q000187:drug effects*; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000627:therapeutic use; D008297:Male; D008874:Midazolam / Q000627:therapeutic use*; D008875:Middle Aged; D009465:Neuromuscular Agents / Q000627:therapeutic use*; D053610:Opiate Alkaloids / Q000627:therapeutic use*; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality / Q000628:therapy; D010043:Outcome and Process Assessment, Health Care; D012042:Registries / Q000706:statistics & numerical data; D016019:Survival Analysis
D006993:Hypnotics and Sedatives; D009465:Neuromuscular Agents; D053610:Opiate Alkaloids; D008874:Midazolam
Awareness; Cardiac arrest; Cardiopulmonary resuscitation; Consciousness