ObjectivesTo identify the risk factors related to the prognosis of carbon monoxide (CO)-poisoned patients in the hospital.DesignRetrospective observational study.SettingTri-Service General Hospital, Taiwan.MethodsWe conducted a review of the medical records of 669 CO-poisoned patients, who were admitted to the Department of Emergency, Tri-Service General Hospital, Taiwan, from 2009 to 2014. Demographic, clinical and laboratory data were collected for analysis. In the study, the end points for poor outcome were patients who either still had sequelae, were bedridden or died after treatment. The independent t-test, χ2 test and binary logistic regression were used to identify the association between the prognostic factors and the outcomes.ResultsThe logistic regression analysis confirmed that the Glasgow Coma Scale (GCS) score (p=0.008) and blood urea nitrogen (BUN) (p=0.002) were related to poor outcomes. Furthermore, the receiver operating characteristic (ROC) curve showed that the cut-off point of intubation days was 1.5 days (area under the ROC curve [AUC]=0.793) for all patients and 2.5 days (AUC=0.817) for patients with intubation when predicting poor outcomes.ConclusionWe identified the factors that most strongly predict the prognosis of CO poisoning, including the GCS score, serum BUN and intubation days. Moreover, the number of hyperbaric oxygen treatments seems to have impact of the outcome.

Carbon monoxide (CO) poisoning is a major public health issue worldwide. People are exposed to CO in their daily lives, with one of the common sources of CO being cigarette smoking. Inhalation of CO leads to elevated carboxyhaemoglobin (COHb) levels in the blood and also in exhaled CO concentration. Several factors have been shown to affect COHb concentration and COHb half-life. However, factors affecting exhaled CO concentration and exhaled CO half-life are not well understood. The present study aimed to investigate the potential factors related to baseline exhaled CO concentration and exhaled CO half-life among smokers. A cross-sectional study was conducted between 26 January and 30 June 2019, and young adults were recruited into the study. A total of 74 participants (mean age: 27.1 years, 71.6% males and 28.4% females) attended the study. They were invited to complete a questionnaire, including demographic, physiological, and behavioural factors. Then, exhaled CO measurements were taken. These measurements were taken before and after smoking a single cigarette for smokers and only once for non-smokers. The average baseline exhaled CO concentration was 6.9 ± 4.9 ppm for smokers and 1.9 ± 0.5 ppm for non-smokers. The mean of exhaled CO half-life was around 273.3 min (4.6 h) for smokers. No difference was seen in exhaled CO half-life between light smokers and heavy smokers in the smoking group. Gender and cigarettes smoked weekly affected baseline exhaled CO in smokers. Even though height seemed to positively associate with exhaled CO half-life, the relationship disappeared when adjusting by gender and weight. Therefore, exhaled CO could be used as a marker of CO exposure, but we cannot ignore the factors mentioned in the study. For future study, considering factors related to smoking habits and smoking style are recommended as these may affect total inhaled CO.

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