Prone restraint death: Possible role of the Valsalva maneuver

There is an on-going debate about the safety of prone restraint and the exact role of the prone position in physical restraint death. Cardiac arrest in prone restraint death is essentially the end-result of a violent physical altercation wherein a combative individual suddenly loses consciousness while trying to counteract an opposing force. The direct correlations of increased static weight force with decreased inferior vena cava diameter, decreased cardiac output, and decreased stroke volume in prone restraint studies suggest that decreased venous return and decreased cardiac output could have a significant role to play in prone restraint death. Although the degree of changes observed in those studies might not be sufficient to cause cardiac arrest, they could predispose people who instinctively try to free themselves of the restraints to severe complications. The Valsalva maneuver, or forceful expiration against a closed airway, is frequently performed spontaneously in daily activities involving straining and resistance exercise, but has never been considered in restraint death. Pre-existing diminished venous return could increase the risk of major complications in individuals performing the Valsalva maneuver. A substantial decrease in venous return and cardiac output could increase the risk of cerebral hypoperfusion, loss of consciousness, hypoventilation, and sudden death. By increasing the risk of increased intra-abdominal pressure and its negative effect on venous return, high body mass index may be a significant risk factor in prone restraint death. The Valsalva maneuver may have different roles in prone restraint cardiac arrest and might be overlooked in prone restraint death.