A 9 y.o. was sitting on a swim platform with her mother and suddenly passed out.
On the way to shore she woke up. What do you need to worry about?
Our patient had carbon monoxide(CO) poisoning. Sitting on the swim platform next to exhaust is dangerous. Since CO is heavier than air it collects at the rear of the boat. There is a peculiar phenomenon which occurs on a boat where exhaust fumes are drawn back into the boat because of low pressure areas at the rear of the boat. This is known as the “station wagon effect”. For those interested there is a diagram below.
Faster moving air around the boat has a higher pressure than the slower moving air behind the boat. This creates a low pressure zone behind the boat and draws exhaust back in
CO poisoning is one of the leading causes of death by poisoning in western countries. In addition to headache, nausea and vomiting, neurologic impairment including syncope is common.
Carbon monoxide is produced from incomplete combustion of carbon-containing fuels. In addition to boats; generators, furnaces, water heaters and gas stoves all produce carbon monoxide. The mechanism of toxicity is hypoxia because the binding affinity of CO to hemoglobin is 200 times that of oxygen. It also has direct effects on the myocardium, depressing ATP production and leading to anaerobic metabolism. It increases the sensitivity of myofilaments and increases intracellular calcium leading to arrhythmias. Autopsy studies of individuals that have died from CO poisoning show necrotic areas similar to myocardial infarcts. Cardiogenic shock has also been reported.
CO poisoning from boating came to public attention with the passage of Sophia’s law in 2017. Sophia Baechler was a 7 y.o who died while sleeping on a boat on Lake Minnetonka in Minnesota. The wind direction had changed blowing exhaust into the cabin where she was sleeping. The law now requires CO detectors on boats in Minnesota longer than 16 ft.
FUN FACTS
Catalytic converters on cars are designed to reduce CO levels in autos. If a car is running in an enclosed space 95% of the the CO is converted to CO2. You can still die of anoxia if CO2 fills an enclosed space. .
The vortex-shedding phenomenon can be observed as wind is shed from a flagpole. This is what causes the regular rippling seen in a flag. Vortices are also shed from bridge piers, pilings, offshore drilling platform supports, and tall buildings.
A Karman vortex is a cloud caused by an obstacle like a mountain obstructing wind flow. Vortices alternate their direction of rotation creating a chain of eddies.
A Karman vortex cloud formation over a mountain.
Bussienne F, Betello M. Cardiogenic shock related to carbon monoxide poisoning. Case Reports Acute Med.,2021. Volume 4(1) 32-35.
Sircar K, Clower J, Shin M et al. Carbon monoxide poisoning deaths in the United States, 1999 to2012. Am J Emerg Med. 2015 Sep;33(9):1140-45.
Gough E. Universe Today Jan 8, 2021 these bizarre cloud patterns are von Karman’s vortices, caused by air wrapping around tall islands.