title: Restraint position and positional asphyxia.
abstract: OBJECTIVE
  To determine whether the "hobble" or "hog-tie" restraint position results in clinically relevant respiratory dysfunction.
  
  
  METHODS
  This was an experimental, crossover, controlled trial at a university-based pulmonary function laboratory involving 15 healthy men ages 18 through 40 years. Subjects were excluded for a positive urine toxicology screen, body mass index (BMI) greater than 30 kg/m2, or abnormal screening pulmonary function testing (PFT). Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and maximal voluntary ventilation (MVV) were obtained with subjects in the sitting, supine, prone, and restraint positions. After a 4-minute exercise period, subjects rested in the sitting position while pulse, oxygen saturation, and arterial blood gases were monitored. The subjects repeated the exercise, then were placed in the restraint position with similar monitoring.
  
  
  RESULTS
  There was a small, statistically significant decline in the mean FVC (from 5.31 +/- 1.01 L [101% +/- 10.5% of predicted] to 4.60 +/- .84 L [88% +/- 8.8% of predicted]), mean FEV1 (from 4.31 +/- .53 L [103% +/- 8.4%] to 3.70 +/- .45 L [89% +/- 7.7%]), and mean MVV (from 165.5 +/- 24.5 L/minute [111% +/- 17.3%] to 131.1 +/- 20.7 L/minute [88% +/- 16.6%]), comparing sitting with restraint position (all, P < .001). There was no evidence of hypoxia (mean oxygen tension [PO2] less than 95 mm Hg or co-oximetry less than 96%) in either position. The mean carbon dioxide tension (PCO2) for both groups was not different after 15 minutes of rest in the sitting versus the restraint position. There was no significant difference in heart rate recovery or oxygen saturation as measured by co-oximetry and pulse oximetry.
  
  
  CONCLUSIONS
  In our study population of healthy subjects, the restraint position resulted in a restrictive pulmonary function pattern but did not result in clinically relevant changes in oxygenation or ventilation.
authors.affiliation: Department of Emergency Medicine, University of California San Diego Medical Center, USA.
authors.forename: T C
authors.initials: TC
authors.lastname: Chan
authors.forename: G M
authors.initials: GM
authors.lastname: Vilke
authors.forename: T
authors.initials: T
authors.lastname: Neuman
authors.forename: J L
authors.initials: JL
authors.lastname: Clausen
mesh_terms: D000293:Adolescent; D000328:Adult; D001237:Asphyxia / Q000209:etiology*; D018592:Cross-Over Studies; D015444:Exercise; D006439:Hemodynamics; D006801:Humans; D008297:Male; D011187:Posture; D012119:Respiration; D012129:Respiratory Function Tests; D012149:Restraint, Physical / Q000009:adverse effects*