The physiological impact of upper limb position in prone restraint

Abstract

Deaths occurring during and/or in close proximity to physical restraint have been attributed to positional asphyxia. This study investigated the physiological impact of three recognized prone-restraint positions with participants remaining passive. Position 3 (P3) the supported prone position (SPP) was designed to reduce the extent of pressure on the anterior chest wall (PAC) by bringing the upper limbs underneath the shoulder joint whereas for the other two positions (P1 and P2) the arms were abducted from the torso. Twenty-five adults participated. Forced vital capacity (FVC), expiratory volume in one second (FEV1), heart rate (HR) and oxygen saturations (SpO2) were taken three times in an upright seated position (baseline) and in each prone position. Mean PAC was measured at 102.6 (±24.3) and 101.4 (±24.4) mmHg for P1 and P2, respectively; however, in the SPP (P3) the mean PAC pressure reduced to 72.7 (±16.9) mmHg. All three prone-restraint positions reduced FVC and FEV1 compared with baseline (P < 0.001). P1 and P2 where the arms were abducted reduced respiratory measures equally but differed from the SPP position (P < 0.001) where PAC was significantly lower. Reductions in FVC from baseline were 16% for P1 and P2, and 11% for the SPP (P3) where PAC was ∼28% lower than in P1 and P2. Reductions in FEV1 were similar in all three prone-restraint positions and HR and SpO2 were unaffected. In summary, all prone-restraint positions restrict respiratory function but the risk associated with the position reduces as the PAC reduces.

Perceptions of supported and unsupported prone‐restraint positions

“…This study provides further support to the findings of Barnett et al . () that in addition to reducing some the physiological risks associated with respiratory restriction, the SPP also reduces some of the psychological impact associated with prone restraint. Based on these results, one would expect that those individuals held in the SPP would feel their breathing was less limited and they would feel less anxious than if held in the USPP.…”

“…Given that Robinson & Hunt () argue that psychological stress may be contributory in fatal cardiac arrhythmias during manual restraint and the negative perceptions reported here may be linked to the ventilatory restriction and anterior chest wall weight bearing imposed by the manual restraint position (Barnett et al . ), it is critical that any emergency prone‐restraint position minimizes both the physiological and psychological impact on the individual to reduce potential adverse outcomes and restraint‐related deaths.…”

“…, and Barnett et al . ). Due to the relationship between the prone position and restraint‐related adverse incidents there have been calls to abolish prone restraint in favour of supine restraint or other restraint positions such as upright seated or standing.…”

“…Barnett et al . () were able to demonstrate that, compared to the Unsupported Prone Position (USPP), the Supported Prone Position (SPP) reduced the physiological risks by reducing ventilatory restriction, and whilst there is clearly an equal need to reduce the negative psychological factors as part of a wider approach to reduce the potential adverse outcomes associated with prone restraint there is a lack of enquiry in the literature (Smith & Bowman , Chow et al . , Larue et al .…”

“…The objective of this study was to build on the existing evidence presented by Barnett et al . () that the SPP reduces physiological risks, by examining if this position is also more effective in reducing the perceived psychological impact of emergency prone restraint when compared with the USPP.…”