Monthly Archives: August 2013

Whitewater safety

It’s been a rough week in southeast Tennessee.  Two people died in two days on Grumpy’s rapid past Ocoee Dam No. 2. Just how common is death due to whitewater rafting?

Wilson et al reviewed 16 articles in the primary literature to determine the specific types of injuries that occur from whitewater rafting and paddling.  They found that the rate on injury is low, and that specific injuries occur with each sport.  Paddling (including kayaking and canoeing) had mostly upper extremity injuries while in the boat.  Lower limb injuries occurred during the hike in or out, or while in the water apart from the boat.  Rafting injuries generally occurred while “swimming” (ie fell out of the boat), and were typically from collision trauma.  Paddling injury rates are roughly 4.5 per 1000 days for novice paddlers, and rafting rates are 26.3 per 100,000 participants (different measures theirs, not mine). There was likely reporting bias for minor injuries, as people not seeking treatment were not reported.

Mildly relevant to the news article, fatality rates from commercial whitewater rafting in New Zealand to range from 0.16-0.27 per 100,000 participants per year. Drowning was indicated in 94% of the fatalities.  Paddling death rates were much higher, at 2.9 per 100,000 participants per year.  The authors attribute this to the fact that most paddling is done with commercial groups, as well as the fact that it is easier to sink a canoe than an 8 person raft.

Perhaps it was simply bad luck, as the death rates in this sport are fairly low. Perhaps more can be done to prevent drowning beyond the required helmets and life jackets. Better epidemiological studies may tease out this. In the meantime, be safe out there.

Injuries, Ill-Health and Fatalities in White Water Rafting and White Water Paddling
http://www.ncbi.nlm.nih.gov/pubmed/23315757

The brain wants oxygen

It goes without saying that the body is designed to work aerobically.  The mind therefore, follows the same pattern.  This essay by Rodway shows historical data and research about the changes in cognition as one goes further up into thin air.  This is important, because they conjecture that many of the problems climbers face are so serious that they have life or death implications, and thus the brain cannot process them as it should, leading to fatal errors.

“Mountaineers have often observed a lack of clarity in their mental state at high altitudes; it is difficult for the stupid mind to observe how stupid it is.”               George Leigh Mallory 1922

He further explains how this is likely a combination of sleeplessness due to periodic breathing as well as hypoxia due to the altitude.  Interestingly, one of the references (Richalet) showed that psychomotor performance and mental efficiency declined progressively with altitudes above 5500m, but differences did not reach statistical significance until 8000m.  Another reference (Waters) in the same paper describes the neuropsychological effects of sleep loss. They include: sleep loss effects both cognitive functions as well brain regions that support cognitive performance; decreased processing speed is most reliable finding after sleep loss; and peformance decreases appear in a dose dependent manner with sleep debt accumulation.

Thus, be aware (and self aware as best as possible) to the problems associated with cognitive function with high altitude climbing. You wouldn’t let a drunk drive you home, don’t let one hold the rope that keeps you alive.

“Decision making at extreme altitude: Has anyone seen my executive function lately?”
http://www.ncbi.nlm.nih.gov/pubmed/22633144