Carbon monoxide poisoning treated with hyperbaric oxygen: metabolic acidosis as a predictor of treatment requirements.
A retrospective case note analysis was made of patients who received hyperbaric oxygen for carbon monoxide poisoning and were admitted to the Royal Naval Hospital Haslar between 1991 and 1995. Males predominated (38 v 10) as did cases of deliberate self poisoning (31 v 17). The most common presenting feature was unconsciousness, which is an indication for hyperbaric oxygen and therefore reflects referral patterns. If patients had not recovered completely after one hyperbaric exposure further treatments were given. The initial hydrogen ion concentration of those requiring more than one treatment was significantly higher than those who recovered after the first treatment. The initial carboxyhaemoglobin (COHb) concentration showed only a trend to being higher in the multiple treatment group. Although metabolic acidosis is well recognised, its relationship to treatment requirements has not been shown previously. Initial COHb does not always correlate well with severity of poisoning which relates to the mechanism of toxicity of carbon monoxide: binding of carbon monoxide to the intracellular oxygen carrying proteins (for example cytochromes) rather than solely to haemoglobin. These findings are consistent with this mechanism and suggests that initial acidosis is a better predictor of treatment requirements and severity than initial COHb.
Turner
M
M
Department of Cardiology, Derriford Hospital, Plymouth, Devon.
Esaw
M
M
Clark
R J
RJ
D000142:Acidosis, Respiratory / Q000209:etiology / Q000628:therapy*; D002248:Carbon Monoxide / Q000097:blood; D002249:Carbon Monoxide Poisoning / Q000150:complications / Q000401:mortality / Q000628:therapy*; D004638:Emergency Treatment; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006931:Hyperbaric Oxygenation / Q000379:methods*; D008297:Male; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012720:Severity of Illness Index; D017678:Sex Distribution; D015996:Survival Rate; D016896:Treatment Outcome; D006113:United Kingdom
D002248:Carbon Monoxide