“Cold water immersion – treatment and practicalities in the field” by Dr. Patrick Buck PhD REMT

Treating a drowning or hypothermic casualty in the field will always present a number of challenges for a first responder.  Psychological stressors, lack of equipment, unfamiliar terrain and perhaps hostile conditions can combine to make the task formidable.

It is for this reason that pre hospital or First Responder training should focus on preventative strategies, prevention is always better than cure and on imparting a set of simplified methodologies for treating and managing such incidents in the field.

When someone falls into cold water four things happen over time.  Firstly they will experience a level of Cold Shock which usually lasts between 1 – 3 minutes (stage 1), followed by Cold Incapacitation, which sets in at around 15 minutes (stage 2) and then Hypothermia which may take 30 – 60 minutes to develop (stage 3).  The rate at which hypothermia develops is related to several factors including body composition, clothing at time of immersion, atmospheric conditions, water state and water temperature.

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Finally some level of Post Rescue Collapse will occur (stage 4).  This is of course providing that the casualty has not already drowned through swim failure.  Without a Personal Floatation Device (PFD), many people in cold water will drown prior to becoming hypothermic because as their muscles stiffen and cramp, it will get progressively more difficult for them to keep their airway from becoming compromised.

Post Rescue Collapse, also known as Circum Rescue Collapse or Peri Rescue Collapse, can be, and often is, fatal.   An estimated 20% of conscious and viable hypothermic casualties recovered from cold water die as a consequence of Post Rescue Collapse either before, during or after rescue.


The primary goal for a First Responder when treating a hypothermic casualty in a pre hospital setting is to try and prevent further heat loss (core body temperature (CBT) drop).  In addition as a ‘cold heart is a fragile heart’, every effort should be made to treat the casualty as gently as possible and to avoid any rough handling.  Ventricular fibrillation is a very real possibility in a hypothermic casualty and in many cases will prove fatal if initiated through incorrect handling or improper rewarming strategies.

As most First Responders are unable in a field setting, due to lack of appropriate equipment, to determine a casualty’s CBT, all obviously hypothermic casualties should be considered as serious until proven otherwise.  As a consequence a casualty should not assist in their rescue nor be encouraged to partake in their treatment, like removing their own wet clothes.

Clinical signs can provide an indication of the casualty’s level of hypothermia, which may in turn assist in their management.

  • If a casualty is shivering but is mentally and physically alert and is acting normally then they are most likely just cold or very mildly hypothermic.
  • If a suspected hypothermic casualty is conscious and shivering then their CBT is most likely at or above 32°C.
  • If a conscious casualty who is obviously hypothermic but is not shivering then their CBT is probably in the region of 30°C-32°C. Note not everyone shivers.
  • If paradoxical undressing occurs then the casualty probably has a CBT between 30°C -32°C.
  • If a suspected hypothermic casualty is unconscious then their CBT is most likely below 30°C. Of course they may have sustained other injuries or have drowned.

Casualty rewarming strategies, where possible, should be initiated in the field.

Rewarming can be achieved using a number of different strategies depending on casualty presentation.

  • Passive external rewarming.
  • Active external rewarming.
  • Active internal rewarming.

A hypothermic casualty with a CBT above 32°C can be treated with insulated blankets, dry clothing, burrito wrapping and warm sweet drinks.  They will be able to rewarm spontaneously.

A hypothermic casualty with a CBT below 32°C will require active rewarming management.  These casualty’s cannot rewarm spontaneously and will require the addition of heat.


In conclusion it must be stressed that every case should be managed on a casualty by casualty basis.  In addition a casualty’s treatment must not compromise other members of the party or group.  Multiple casualties present a much more significant challenge for a First Responder in a pre hospital setting.

Finally a Hypothermic Casualty Is Never Dead Until They Are Warm And Dead Unless Patently Dead.

BIOGpicDr. Patrick Buck, Ph.D REMT, is a marine biologist, educator, adventurer and environmentalist.  He is currently Director of Inland Fisheries in the SW of Ireland. Patrick has extensive experience in marine survival and a deep passion for remote medicine and its application in the marine environment. He is currently conducting applied research in the area of marine survival and hypothermia and is specifically interested in modified PFD design to prolong life in austere settings. He is an avid water sports enthusiast with over 40 years experience in surfing, kayaking and marine guiding. Patrick is a director of WATER SAFETY 4 ALL, a ‘not for profit’ organisation dedicated to bringing safety and fun to all water users from all walks of life.




Dr. Buck is the author of “A field guide for the treatment of drowning, hypothermia & cold water immersion incidents”. This guide is available through the WATER SAFETY 4 ALL  website: http://watersafety.eu  It is also available from Amazon.com as an E-book (immediately) or physical book (from 30th January 2015 onward) at select book shops.

ISBN 978-0-9930432-0-8

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