Defence Research and Development Canada Recherche et développement pour la défense Canada Canada Self-rescue during accidental cold water immersion: is swimming an option? Michel B. Ducharme & David S. Lounsbury Human Protection and Performance, Defence R&D Canada – Toronto
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Self-rescue during accidental cold water immersion: is swimming an option?
Self-rescue during accidental cold water immersion: is swimming an option?. Michel B. Ducharme & David S. Lounsbury Human Protection and Performance, Defence R&D Canada – Toronto. Background. The problem of accidental cold water immersion…. drowning is the leading cause of accidental death - PowerPoint PPT Presentation
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Defence Research andDevelopment Canada
Recherche et développementpour la défense Canada Canada
Self-rescue during accidental cold water immersion:is swimming an option?
Michel B. Ducharme & David S. LounsburyHuman Protection and Performance,
Defence R&D Canada – Toronto
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
Background
The problem of accidental cold water immersion…
• drowning is the leading cause of accidental death for recreational activities in Canada (The National Drowning Report, 2003)
• 35 % of drowning occur in cold water (National Drowning Trends Report, 2006)
• BC Fishing Industry: 95 % of drowning occur
in water with a temperature ≤ 15 ºC (Brooks et al, Occupational. Med, 2005)
• 2007 persons died of cold immersion in Canada during 1991-2000 (The National Drowning Report, 2006)
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
What should a person do upon accidentalimmersion in cold water?
Would you attempt a 300 m swim in 10C wearing a PFD over seasonal clothing?
Result of survey:70% of final year university graduates said “NO”
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
Background
• public safety information agencies
– cold water swimming distance is only 1/10 of warm
water swimming distance (CRCS, 1983)
– attempting a swim of 100 m in cold water is too risky,
even for PFD-wearers (CRCS, 1995)
– “Do not attempt swimming. It has been shown that a strong swimmer has only a 50/50 chance of reaching shore one-half mile away.” (RLSSC, 1997)
– “If immersion is from a capsized craft: wait for rescue. Don’t try to swim for safety unless you are sure you can make it - you cool faster than you think.” (Ministry of the Environment)
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
Background
• public safety information agencies
– Cold water can paralyze your muscles instantly
(Transport Canada, 2006)
- If you end up in the water, do everything you can to conserve energy and body heat…Do not swim to keep warm. (Transport Canada, 2006)
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
Background
• rationale for the recommendations
– Subjects were only able to swim 7 to 12 min in 5°C water (Keatinge et al., 1969)
– moderate intensity swimming (40 - 45 % VO2 MAX) in 10.5 °C water can cause a 35 % in heat loss compared to holding steady (Hayward et al, 1975)
– hypothermia was assumed to be the limiting factor to swimming in cold water (Pugh 1955, Hayward et al, 1975)
– each °C in TEs or TM induces a 5 - 6 % in VO2 MAX (Bergh and Ekblom, 1979)
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
Background
“the traditional naval advice to cling to wreckage and not to waste energy by swimming is probable correct” (Pugh and Edholm, 1955)
“people are better off if they float still in lifejackets or hang on to wrekage and do not swim about to try to keep warm” (Keatinge, 1972)
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
In 2006…
“If rescue is unlikely, it may be preferable to swim to safety”(CRCS, 2006)
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
New evidence (epidemiological studies)
1- More survivors of boating incidents swam for shore thanstayed with the boat (Sawyer and Barss, 1998)
2- 60% of survivors of cold water boating immersions swamfor shore as opposed to only 30% who stayed with the boat(CRCS, 2006)
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
New evidence (physiological studies)
1- Subjects not wearing PFD could swim on average 55 min in 10°C water (Tipton et al., 1999)
2- Subjects wearing a PFD could swim on average 889 min 14°C water before incapacitation (Wallingford, Ducharme et al, 2000)
3- Subjects wearing a PFD could swim on average 792 min 10°C water before incapacitation, 3 times shorter thanthe 2375 m in 24°C (Kenny, Ducharme et al., 2001; 2002)
4- Subjects wearing a PFD could swim on average 806 m(novice swimmer) and 1439 m (expert swimmer) in 10°Cwater before incapacitation (Lounsbury and Ducharme, 2005)
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
New evidence (physiological studies)
0
500
1000
1500
2000
2500
3000
0 5 10 15 20 25 30
Water Temperature (°C)
Sw
im D
ista
nce
(m
)
A
B C1
C2
D
E A: Keatinge et al., 1969
B: Kenny et al., 2001
C1: Lounsbury & Ducharme, 2005 (novice swimmers)
C2: Lounsbury & Ducharme, 2005 (expert swimmers)
D: Wallingford et at., 2000
E: Kenny et al., 2001
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
New evidence (physiological studies)
0
500
1000
1500
2000
2500
3000
0 5 10 15 20 25 30
Water Temperature (°C)
Sw
im D
ista
nce
(m
)
A
B C1
C2
D
E A: Keatinge et al., 1969
B: Kenny et al., 2001
C1: Lounsbury & Ducharme, 2005 (novice swimmers)
C2: Lounsbury & Ducharme, 2005 (expert swimmers)
D: Wallingford et at., 2000
E: Kenny et al., 2001
?
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
New evidence (physiological studies)
The average swimming duration in all studies was about 45-50 min before incapacitation, irrelevant to the swimming ability
Swimming failure develops before incapacitating hypothermia
Swimming failure is likely primarily related to muscle fatigueof the arms as a consequence of muscle cooling rather thanhypothermia
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
Recommendations for self-rescue
1- Upon falling into water (cold shock):- focus on keeping the head above water- do not swim until regaining control of breathing
2- Ask yourself: “Am I likely to be rescued soon?”- <10% body fat: 2-3 hours- 15-20% body fat: 4-5 hours- >30% body fat: several hours- Yes: use HELP posture
3- No: swimming is an option- look around for the nearest source of safety- try to assess if you can swim the distance based on
your ability to swim and level of fitness- can you swim the required distance within 45-50 min?
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
Recommendations for self-rescue
4- Once you have made your decision, hold on to it, as your judgment will become impaired with time
5- Try to swim with an even and sustained pace
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
Swimming distance in cold water
Km
m
Fat, fit, good swimmer
Thin, unfit, bad swimmer
Average fatness, fit, novice
Average fatness, fit, expert
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
The Defence Research
and Development Branch
provides Science and
Technology leadership
in the advancement and
maintenance of Canada’s
defence and security
capabilities.
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
Objective of the study
To compare two self-rescue strategies (e.g. swimming vs. preserving heat) for their thermal performance during immersion in cold water.
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
Hypothesis of the study
- Swimming will induce a higher body heat loss as compared to HELP
- Swimming will not induce a higher change in body heat content as compared to HELP
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
Methods - Subjects
• 15 subjects between 18 to 55 years of age
• either gender
• attempts made to recruit across a wide range of body sizes and somatotypes
• classified by swimming skill into “novice” or “expert” categories
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
Methods - Subject Characteristics
• Novice (n=7)
Age = 31.7 years
Height = 1.73 m
Mass = 69.8 kg
BMI = 23.0 kg/m2
BSA = 1.82 m2
BSA:mass = 0.027 m
%BF-SkF = 17.4
%BF-UWW = 13.7
VO2 MAX Trd = 42.1* mL/kg/min
VO2 MAX Arm = 20.4 mL/kg/min
Aqua Quest Level = 7*
• Expert (n=8)
Age = 31.0 years
Height = 1.74 m
Mass = 74.4 kg
BMI = 24.5 kg/m2
BSA = 1.89 m2
BSA:mass = 0.026 m
%BF-SkF = 15.0
%BF-UWW = 13.3
VO2 MAX Trd = 52.1* mL/kg/min
VO2 MAX Arm = 24.6 mL/kg/min
Aqua Quest Level = 11*
Total Subject Pool (n=15)
* - NOV vs. EXP (p<0.05)
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto
Methods - Design
0 3 45? 120time (min)
Trial 1: Passive Cooling (PC)
Trial 2: Free Swimming (FS)
HELP
HELP Free Swimming HELP
TRec (°C)37 34
Nov.
Exp.
Nov.
Exp.HELPHeat EscapeLessing Position
Coldshock
Defence R&D Canada – Toronto • R & D pour la défense Canada – Toronto