title: Elevation of post mortem vitreous humour sodium and chloride levels can be used as a reliable test in cases of suspected salt water drowning when the immersion times are less than one hour.
abstract: BACKGROUND
  Previous studies in salt water drowning deaths (SWD) demonstrated an observable elevation of post mortem vitreous sodium and chloride (PMVSC) levels. It remains unclear what the underlying mechanism responsible for this change is: whether this is due to rapid electrolyte changes from salt water inhalation/ingestion during drowning or from electrolyte diffusion and/or osmosis across the outer coats of the eyeballs during immersion. A recent animal study using sacrificed bovine eyeballs immersed in salt water demonstrated no significant elevations in PMVSC when immersed for less than one hour. Assuming similar physical properties between human and bovine, we extrapolate that an elevation in PMVSC in SWD with immersion times of less than one hour (SWD-1) would not be from immersion, but from drowning.
  
  
  OBJECTIVE
  Investigate whether there is an elevation in PMVSC in SWD-1.
  
  
  METHODS
  Retrospective study comparing PMVSC in SWD-1 with controls from 2012 to 2015 inclusive.
  
  
  RESULTS
  PMVSC in SWD-1 was significantly elevated compared with controls. A PMVSC of 259mmol/L has a sensitivity, specificity and likelihood ratio of 0.9, 0.9 and 7.6, respectively.
  
  
  CONCLUSIONS
  The elevation in PMVSC in SWD-1 is due to drowning. A PMVSC of 259mmol/L and above is a reliable ancillary test in diagnosing drowning in bodies immersed in salt water for less than one hour.
authors.affiliation: School of Medicine and Public Health, Faculty of Health and Medicine, University of Newcastle, Callaghan, New South Wales, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Garland
authors.affiliation: Department of Forensic Medicine, Newcastle, Forensic & Analytical Science Service (FASS), NSW Health Pathology, John Hunter Hospital, Newcastle, New South Wales, Australia. Electronic address: rexson.tse@hnehealth.nsw.gov.au.
authors.forename: R
authors.initials: R
authors.lastname: Tse
authors.affiliation: School of Medicine and Public Health, Faculty of Health and Medicine, University of Newcastle, Callaghan, New South Wales, Australia; Public Health Stream, Hunter Medical Research Institute, Newcastle, New South Wales, Australia.
authors.forename: C
authors.initials: C
authors.lastname: Oldmeadow
authors.affiliation: School of Medicine and Public Health, Faculty of Health and Medicine, University of Newcastle, Callaghan, New South Wales, Australia; Public Health Stream, Hunter Medical Research Institute, Newcastle, New South Wales, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Attia
authors.affiliation: Blacktown Hospital, New South Wales, Australia.
authors.forename: S
authors.initials: S
authors.lastname: Anne
authors.affiliation: Department of Forensic Medicine, Newcastle, Forensic & Analytical Science Service (FASS), NSW Health Pathology, John Hunter Hospital, Newcastle, New South Wales, Australia.
authors.forename: A D
authors.initials: AD
authors.lastname: Cala
mesh_terms: D001344:Autopsy; D002712:Chlorides / Q000032:analysis*; D004332:Drowning / Q000175:diagnosis*; D044707:Forensic Sciences / Q000379:methods*; D006801:Humans; D012189:Retrospective Studies; D012964:Sodium / Q000032:analysis*; D013997:Time Factors; D014822:Vitreous Body / Q000737:chemistry*
chemical_list: D002712:Chlorides; D012964:Sodium
keywords: Drowning; Post mortem vitreous humour; Salt water; Sea water; Sodium; chloride