Prone restraint cardiac arrest: A comprehensive review of the scientific literature and an explanation of the physiology

Abstract

Deaths occurring among agitated or violent individuals subjected to physical restraint have been attributed to positional asphyxia. Restraint in the prone position has been shown to alter respiratory and cardiac physiology, although this is thought not to be to the degree that would cause asphyxia in a healthy, adult individual. This comprehensive review identifies and summarizes the current scientific literature on prone position and restraint, including experiments that assess physiology on individuals restrained in a prone position. Some of these experimental approaches have attempted to replicate situations in which prone restraint would be used. Overall, most findings revealed that individuals subjected to physical prone restraint experienced a decrease in ventilation and/or cardiac output (CO) in prone restraint. Metabolic acidosis is noted with increased physical activity, in restraint-associated cardiac arrest and simulated encounters. A decrease in ventilation and CO can significantly worsen acidosis and hemodynamics. Given these findings, deaths associated with prone physical restraint are not the direct result of asphyxia but are due to cardiac arrest secondary to metabolic acidosis compounded by inadequate ventilation and reduced CO. As such, the cause of death in these circumstances would be more aptly referred to as “prone restraint cardiac arrest” as opposed to “restraint asphyxia” or “positional asphyxia.”

Response to: Response to: Prone restraint cardiac arrest: A comprehensive review of the scientific literature and an explanation of the physiology

“…I would like to thank Dr Vilke and his colleagues for their response to my recent publication. 1,2 I highlighted their work because I felt it was important to address their faulty conclusions regarding the significance of ventilatory and physiologic changes associated with prone restraint. I am happy to have the opportunity to address their comments.…”

The prone position paradox

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Dr Steinberg presented a passionate critique of the prone-restraint position but did not present an alternative approach for positioning of the resistant subject. 1,2 Considering the comorbidities, the mortality rate of nonfirearm arrest-related death (ARD) of 1:1000 is impressive compared to 1:232 for elective ablation of atrial fibrillation. 3,4 About 82% of the subjects involved in use-of-force events are affected by alcohol, drugs, or emotional disturbance.

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Response to: Prone restraint cardiac arrest – A comprehensive review of the scientific literature and an explanation of the physiology

“…We read with interest the recent review article by Steinberg titled ‘Prone restraint cardiac arrest: A comprehensive review of the scientific literature and an explanation of the physiology’. 1 We appreciate the author highlighting our work in a separate section, as well as reviewing the scientific studies of many of our colleagues, but urge caution in the author's conclusion these sudden deaths in agitated individuals restrained in the prone position are ‘most likely due to metabolic acidosis exacerbated by inadequate ventilation and a decrease in CO (cardiac output)’.…”