Carbon monoxide (CO) poisoning is a mimic and can be a “silent killer,” especially in winter or during electrical outages from storms. In 2005 along the Gulf Coast, five people died from CO poisoning after Hurricane Katrina. Also, in 2005, in Beaumont, another five — in one family — died after Hurricane Rita; they had run a gasoline-fueled generator inside their apartment. From 1999 to 2012, the yearly average of 438 deaths from accidental CO poisoning did not decline substantially (1). We need much greater awareness and more public health measures, because these tragic deaths are preventable.
Because CO is colorless and odorless, the illness is insidious, the symptoms are nonspecific, and the victims and observers can be unaware of the risk, CO poisoning is a potential threat in some sports, recreational activities, and other pursuits. Let me give examples.
In February 2017, nine children and a coach became ill — breathlessness, fatigue, nausea, vomiting — during a hockey game in an indoor ice rink in Delaware. They were treated for poisoning from CO emitted by the ice resurfacing machine, or “Zamboni.” The same occurred at an indoor rink in New Jersey in 2013 — seven children became sick playing ice hockey, were treated in the hospital for CO poisoning, and the Zamboni was blamed.
In fact, unhealthy levels of CO in indoor ice arenas have been reported over and over again for nearly 50 yr (2). In December 2014, a “mass casualty event” occurred at a Wisconsin indoor rink, where a player lost consciousness after an ice hockey game and 74 people (32 hockey players, 42 spectators) who went to emergency rooms were diagnosed with CO poisoning, blamed on the Zamboni. Symptoms included headache, nausea, vomiting, dizziness, and shortness of breath. The player who became unconscious had the highest level of carboxyhemoglobin (COHb) at 22% (3).
A new study gauged COHb levels (by Masimo Rad-57 pulse CO-oximeter) in ice hockey players (ages, 8 to 18 years) in indoor arenas. Studied were 37 players in arenas using internal combustion (IC) resurfacers (the IC group) versus 36 players in arenas using electric resurfacers. The IC group had a higher median COHb level pregame (4% vs 1%) and a greater rise in COHb during the game (3% vs 1%). CO was detected in the air in 75% of the arenas using an IC resurfacer, and during the ice hockey game, the rise in COHb was proportional to the amount of CO in the air. No CO was detected in the air at any arena using an electric resurfacer (4).
It appears that the risk of CO poisoning in indoor ice rinks using electric resurfacers is next to zero. The Zamboni Company, with the largest market share of ice resurfacers, now sells roughly equal numbers of IC and electric resurfacers (4). Granted, electric resurfacers cost maybe 50% more than IC resurfacers. However, after many outbreaks of CO poisoning from IC resurfacers over the past five decades, how many more poisonings will it take for all indoor ice rinks to use electric resurfacers?
Low Index of Suspicion
Recognizing CO poisoning early on can be difficult, especially for lay people, in part because the symptoms can mimic food poisoning or “the flu” without fever. In the winter of 2005, the same year as the CO deaths after Hurricanes Katrina and Rita, a Utah lawyer who lived alone died from CO poisoning. His boiler heating system had a cracked gasket. He looked ill at work on a Friday. A coworker noted that he had nausea, had vomited, had a flushed face and a mild cough, “like a cold was starting.” The more time he spent away from home, the better he felt. He even went to an office party on Saturday and to dinner with a friend on Monday. However, he failed to show up for work on Tuesday and was found dead at home, with high CO levels in the indoor air. No one figured it out in time (5).
Emergency medical services (EMS) responders also can have a low index of suspicion. Austrian physicians reported unrecognized CO exposure. An older man was found unconscious in his basement. EMS was called. On seeing ST segment elevations on electrocardiogram (ECG), they treated him for an acute coronary syndrome. Then, the EMS staff began to feel ill and called the fire department, who sent 11 EMS personnel and the initial patient to the hospital, where all 12 were treated for CO poisoning. The unconscious man had a COHb level of 22% and EMS personnel had levels of 10% to 17%. All survived. The authors advise: “Treat the patient, not the ECG.” They note that ST elevation coronary syndrome alone would not explain the patient’s unconsciousness (6).
CO poisoning can even be missed at autopsy. Tennis star Vitas Gerulaitis died in September 1994 at age 40 yr from CO poisoning, as he napped in a pool cottage on a friend’s estate, and unknowingly inhaled CO from a new but faulty propane swimming pool heater in the basement of the cottage. You would think this would be remembered. Yet in June 2013, when an 11-year-old boy staying with his mother in a hotel room in Boone, NC — a second-floor room directly above the room with a natural gas heater for the bottom-floor swimming pool — died from CO poisoning, it was disclosed that 2 months earlier an elderly couple had died in the same room! Yet the medical examiner did not view the bodies at the scene, listed “overdose” as the likely cause of death, and did not request a rapid test for CO. Confirmation that the couple died from CO poisoning came only after the child died. Sad but true (7).
In 1986, two young male mountain climbers using a butane cook stove in a tent at 14,200 ft on Mount McKinley died from CO poisoning. The physicians who reported these deaths noted that mild to moderate CO poisoning could mimic the signs and symptoms of acute mountain sickness (8). In 1993, two military men in Norway died in a similar manner in a tent in deep snow. Many anecdotal reports exist of CO poisoning — in tents, snow caves, or igloos, in deep snow and/or on mountains — from Alaska to California to Mount Everest to Antarctica, as extensively reviewed (9). In an experiment, seven male volunteers used a kerosene camping stove in a small tent. After 2 h, all had notable levels of COHb (mean, 22%), all had a sharp increase in heart rate, and most reported mild headache and dizziness. Two hours later, all felt fine. The authors said they did not expect COHb to rise that high, and if they could do it over again, their design would be different (10). Fortunately, the “vent the tent” word has spread, and unless there is underreporting, coma or death from CO poisoning now seems rare in the mountaineering community.
Recreational Activities and Other Pursuits
CO poisoning still occurs, however, in some recreational activities and in other pursuits. For example, a hazard of “mud bogging” was shown in 2013 by the CO poisoning death of MTV Buckwild star Shain Gandee, age 21 yr, along with his uncle and another man, when their truck got stuck and mud plugged the exhaust pipe. Similar nonfatal cases have been reported in mud bogging (11).
CO poisoning also occurs in children riding in the back of pickup trucks. For example, 20 such cases were reported in 1992; COHb levels tended to be high, 15 children were unconscious, and one child died. On analysis, 17 were riding under a rigid closed canopy on the rear of the truck, and three were riding under a tarpaulin (12).
CO poisoning occurs among recreational boaters too. A 1995 report detailed 39 cases, most of them severe (13). Despite this warning, a report 20 yr later, surveying CO poisoning among boaters nationally, found an average of seven deaths a year (from 2002 to 2011), most on cabin motorboats, but some on open motorboats or houseboats. The authors note that underreporting of CO poisoning among boaters seems likely (14).
As for pursuits, CO poisoning occurs among hookah smokers, who are exposed to 10 times the inhaled CO as cigarette smokers, from the burning charcoal briquette atop the water pipe (15). It seems that hookah smokers have not learned the lesson of grave or fatal CO poisoning from the indoor burning of charcoal briquettes, reported in detail (79 patients) nearly 25 yr ago (16).
In conclusion, we can do more to prevent CO poisoning. Greater public awareness and more public health measures are vital. Wider use of CO monitors and alarms will help. Earlier diagnosis and prompt oxygen therapy also can save lives. Wider use of the newer handheld pulse CO oximeters may help. A concise clinical review has practical tips on diagnosis, management, and prevention (17).
The author declares no conflict of interest and does not have any financial disclosures.
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