Weight Force During Prone Restraint and Respiratory Function

Abstract

Prone maximal restraint position (PMRP, also known as hogtie or hobble) is often used by law enforcement and prehospital personnel on violent combative individuals in the field setting. Weight force is often applied to the restrained individual's back and torso during the restraint process. We sought to determine the effect of 25 and 50 lbs weight force on respiratory function in human subject volunteers placed in the PMRP. We performed a randomized, cross-over, controlled trial on 10 subjects placed in 4 positions for 5 minutes each: sitting, PRMP, PRMP with 25 lbs weight force (PMRP+25), and PRMP with 50 lbs weight force placed on the back (PMRP+50). We measure pulse oximetry, end-tidal CO2 levels, and forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1). FVC and FEV1 were significantly lower in all restraint positions compared with sitting but not significantly different between restraint positions with and without weight force. Moreover, mean oxygen saturation levels were above 95% and mean end-tidal CO2 levels were below 45 mm Hg for all positions. We conclude that PMRP with and without 25 and 50 lbs of weight force resulted in a restrictive pulmonary function pattern but no evidence of hypoxia or hypoventilation.

Review of the medical and legal literature on restraint chairs

“…30,44 Reports of sudden death in individuals while in this position have been reported in the medical literature for the past few decades, which has created some controversy regarding its safety. 30,36,45 It has been hypothesized that the PMRP prevents adequate chest and abdominal movement and places the individual at risk for asphyxiation. 36,41,42 The result of these deaths are likely multifactorial, with many factors difficult or impossible to replicate or measure.…”

“…33 Two additional studies of healthy subjects focused on ventilator measures while in the PMRP with progressive weight increases on the subjects back also reported similar results. 30,46 One of the more recently researched associations with custody deaths is ExDS. Despite the relatively low incidence of ExDS, the syndrome has been reported to have a high fatality rate and is often associated with the use of illicit drugs.…”

“…When an individual is in this position, they are prone with his/her wrists secured behind the back, ankles bound together, and wrists and ankles tied together using handcuffs, cords, chains, or hobble devices. 30,43 This restraint method has been commonly used in the field by law enforcement personnel and in correctional settings. 30,44 Reports of sudden death in individuals while in this position have been reported in the medical literature for the past few decades, which has created some controversy regarding its safety.…”

“…30,43 This restraint method has been commonly used in the field by law enforcement personnel and in correctional settings. 30,44 Reports of sudden death in individuals while in this position have been reported in the medical literature for the past few decades, which has created some controversy regarding its safety. 30,36,45 It has been hypothesized that the PMRP prevents adequate chest and abdominal movement and places the individual at risk for asphyxiation.…”

Deaths in custody: Are some due to electronic control devices (including TASER® devices) or excited delirium?

“…In a series of 21 cases of death associated with excited delirium, 86 all of the subjects had undergone restraint. Chan et al 87 concluded that such a position resulted in a ''restrictive pulmonary function pattern," but with no evidence of hypoxia (i.e., no O 2 saturation less than 96%). This conclusion was based upon observations of normal subjects (not exhibiting excited delirium).…”