Carbon monoxide poisoning

Effects of acute carbon monoxide poisoning on liver damage and comparisons of related oxygen therapies in a rat model

Acute carbon monoxide (CO) poisoning may cause liver damage and liver dysfunction. Therefore, in this study, we aimed to compare the efficiency of normobaric oxygen (NBO) and high-flow nasal cannula oxygen (HFNCO) treatments on liver injury. For that purpose, 28 male Wistar albino rats were divided into four groups (Control, CO, CO + NBO, and CO + HFNCO). The control group was allowed to breath room air for 30 min. Acute CO poisoning in CO, CO + NBO, CO + HFNCO was induced by CO exposure for 30 min. Thereafter, NBO group received 100% NBO with reservoir mask for 30 min. HFNCO group received high-flow oxygen through nasal cannula for 30 min. At the end of the experiment, all animals were sacrificed by cardiac puncture under anesthesia. Serum liver function tests were measured. Liver tissue total antioxidant status (TAS), total oxidant status (TOS), and oxidative stress index (OSI) levels, tissue histomorphology and immunoexpression levels of Bax, Caspase 3, TNF-α, IL-1β, and NF-κB were also examined. Our observations indicated that acute CO poisoning caused significant increases in blood COHb, serum aminotransferase (AST), alanine aminotransferase (ALT0, alkaline phosphatase (ALP), total protein, albumin, and globulin levels but a decrease in albumin to globulin ratio (all, p < 0.05). Furthermore, acute CO poisoning significantly increased the OSI value, and the immunoexpresssion of Bax, Caspase 3, TNF-α, IL-1β, and NF-κB in liver tissue (all, p < 0.05). These pathological changes in serum and liver tissue were alleviated through both of the treatment methods. In conclusion, both the NBO and HFNCO treatments were beneficial to alleviate the acute CO poisoning associated with liver injury and dysfunction.

Recent trends in an uncommon method of carbon monoxide suicide

PURPOSE

The most prevalent method of carbon monoxide (CO) suicide is inhalation of vehicle exhaust (VE). However, a new method of CO suicide has recently emerged involving charcoal burning (CB) in a confined space to produce fatal CO levels. This method has been reported from countries in Asia, associated with economic instability and media reporting of high-profile celebrity cases. The current study was undertaken to analyze rates and characteristics of CB suicides in South Australia (SA) for comparison with respect to their characteristics and scene, autopsy and toxicology findings.

METHODS

A search was undertaken for all intentional fatal carbon monoxide poisonings in SA between 2000 and 2019. Collected variables included age, sex, cause of death, location of death, decedent histories, scene, autopsy and toxicology findings and manner of death. Statistical analyses were performed using R (version 4.2.3).

RESULTS

There was a significant decrease in VE suicides (p < 0.05) and a significant increase in CB suicides (p < 0.001) over the 20-year period. Those who used CB were found to be, on average, between 1.5 and 15.8 years younger than those who used VE (p = 0.017). The risk factors for CB suicide included psychological/psychiatric conditions and financial problems, while VE suicides were associated with a history of physical problems and contact with the legal system. External and internal autopsy findings were consistent with the literature.

CONCLUSION

CB suicide is perceived to be widely accessible and painless and is therefore becoming a popular suicide method. Monitoring future trends will be important to determine whether intervention is required.

The spectrum of presentations of unintentional carbon monoxide poisoning

Carbon monoxide (CO) is an odourless and tasteless gas which can be produced by the incomplete combustion of carbon-containing fuels. Compared to vehicular CO suicides, unintentional cases (excluding those related to fires) are much less common. Increased education surrounding the risks associated with the accumulation of CO in enclosed spaces has contributed to a reduced incidence of unintentional CO poisonings. However, such cases may remain undetected, particularly in domestic and recreational settings where scene findings are often non-specific. The current study of unintentional CO poisonings in South Australia and the Northern Territory, each with a unique climate (Mediterranean and tropical respectively), demonstrated differences in the circumstances of death. Several cases where individuals used carbon-producing fuel sources for heat, both in domestic and vehicular settings and without adequate ventilation, resulted in fatal outcomes. Less common scenarios involved faults in equipment (e.g. a hot water heater), vehicle faults resulting in the accumulation of fatal levels of CO in enclosed spaces, and inadvertent introduction of CO into a diving oxygen supply in a recreational aquatic setting. In ascertaining the cause of death, other considerations include the potential role of underlying chronic cardiovascular and respiratory disease and age which may increase an individual's susceptibility to CO toxicity. Understanding the wide variety of presentations and contributing factors in cases of fatal CO poisoning including consideration of climate-specific differences in domestic and extra-domestic settings may enable improved detection at autopsy.

Burn index, burn characteristics and carboxyhemoglobin levels in indoor fire-related deaths: Significance and interpretation of the autopsy findings

INTRODUCTION

The Burn Index (BI) is a significant clinical prognostic parameter for patients with burns. It simultaneously considers major mortality risk factors: age and burns extensivity. Despite the inability to distinguish between ante- and post-mortem burns, their characteristics on autopsy might indicate if a significant thermal injury occurred before the onset of death. We investigated whether autopsy BI, burn extensivity, and severity could tell whether burns were the concurrent cause of fire-related death (FRD), even if the body remained in a fire.

MATERIAL AND METHODS

Ten-year retrospective study analyzed FRD that occurred at the scene in a confined space. Soot aspiration was the main inclusion criterion. Autopsy reports were reviewed for demographic data, burn characteristics (degree, Total Body Surface Area burned- TBSA), coronary artery disease, and blood ethanol. We calculated the BI as a sum of the victim's age and percentage of TBSA affected by 2nd, 3rd and 4th-degree burns. Cases were divided into two groups: those with COHb≤ 30% and with COHb> 30%. Subjects with burned TBSA≤ 40% were analyzed separately afterward.

RESULTS

The study included 53 males (71.6%) and 21 females (28.4%). No significant difference in age was observed between groups (p > 0.05). COHb≤ 30% had 33, and COHb> 30% had 41 victims. BI and burns extensivity (TBSA) had significant negative correlation with COHb values (ρ = -0.581, p < 0.01 and ρ = -0.439, p < 0.01, respectively). Both were significantly higher in subjects with COHb≤ 30% compared to those with COHb> 30% (140.7 ± 29.57 vs. 95.49 ± 38.49, p < 0.01 and 98 (13-100) vs. 30 (0-100), p < 0.01, BI and TBSA respectively). BI had excellent and TBSA fair performance for detection of subjects with COHb≤ 30% on ROC curve analysis (AUCs 0.821, p < 0.001 and 0.765, p < 0.001), with optimal cut-off values: BI≥ 107 (sensitivity 81.3%, specificity 70.7%) and TBSA≥ 45 (sensitivity 84.8%, specificity 70.7%). On logistic regression analysis BI≥ 107 was independently associated with COHb≤ 30% values (aOR 6; 95%CI 1.55-23.37). The same holds for the presence of 3rd-degree burns (aOR 5.9; 95%CI 1.45-23.99). In the subgroup of subjects with TBSA≤ 40% burned, those with COHb≤ 50% were significantly older than victims with COHb> 50% (p < 0.05). Here BI≥ 85 was a particularly good predictor for detection of subjects with COHb≤ 50% (AUC=0.913, p < 0.001, 95% CI 0.813-1.00; sensitivity 90.9%, specificity 81%).

CONCLUSION

The BI≥ 107, TBSA≥ 45% burned, and 3rd-degree burns observed on autopsy point to a significantly higher odds that limited CO intoxication occurred, and burns should be considered a concurrent cause of indoor FRD. When less than 40% of TBSA was affected, BI≥ 85 indicated sub-lethal CO poisoning.

Improving Household Safety via a Dynamic Air Terminal Device in Order to Decrease Carbon Monoxide Migration from a Gas Furnace

The airtightness of buildings is continuing to grow and impact the indoor environment. Its aim is to conserve energy, but this may influence the indoor air quality and increase contaminant accumulation by limiting the amount of fresh air that infiltrates the building. The goal of this study was to quantify how the contaminants from a faulty gas furnace in a household could impact the occupants. The gas furnace was located in an attached garage and leaked carbon monoxide (CO). Multizone and CFD simulations were caried out to determine if an air terminal device (ATD) with a changing geometry could improve the air quality. The goal of the ATD was to maintain a steady air throw in the garage, while the air flow in the ventilation system would change. A steady air throw should help to remove the carbon monoxide generated from the furnace and prevent infiltration into the household. The results show that with the use of the new ATD, it was possible to maintain a steady air throw and the infiltration of CO was lowered.

Quantifying the Effects of Climate Factors on Carbon Monoxide Poisoning: A Retrospective Study in Taiwan

Background: Carbon monoxide (CO) poisoning is the leading cause of poisoning death worldwide, but associations between CO poisoning and weather remain unclear. Objective: To quantify the influence of climate parameters (e.g., temperature, relative humidity, and wind speed) on the incidence risk of acute CO poisoning in Taiwan. Methods: We used negative binomial mixed models (NBMMs) to evaluate the influence of weather parameters on the incidence risk of acute CO poisoning. Subgroup analyses were conducted, based on the seasonality and the intentionality of acute CO poisoning cases. Results: We identified a total of 622 patients (mean age: 32.9 years old; female: 51%) with acute CO poisoning in the study hospital. Carbon monoxide poisoning was associated with temperature (beta: -0.0973, rate ratio (RR): 0.9073, p < 0.0001) but not with relative humidity (beta: 0.1290, RR: 1.1377, p = 0.0513) or wind speed (beta: -0.4195, RR: 0.6574, p = 0.0806). In the subgroup analyses, temperature was associated with the incidence of intentional CO poisoning (beta: 0.1076, RR: 1.1136, p = 0.0333) in spring and unintentional CO poisoning (beta: -0.1865, RR: 0.8299, p = 0.0184) in winter. Conclusion: Changes in temperature affect the incidence risk for acute CO poisoning, but the impact varies with different seasons and intentionality in Taiwan. Our findings quantify the effects of climate factors and provide fundamental evidence for healthcare providers to develop preventative strategies to reduce acute CO poisoning events.

Prediction of troponin I and N-terminal pro-brain natriuretic peptide levels in acute carbon monoxide poisoning using advanced electrocardiogram analysis, Alexandria, Egypt

The study aimed at assessing the diagnostic ability of advanced electrocardiogram (ECG) analysis to predict the levels of NT-proBNP and Troponin I. ECG and the blood NT-proBNP and Troponin I were taken from 50 acutely carbon monoxide poisoned patients and 21 control subjects matched with age and sex. The severity of the studied cases was classified into mild, moderate, and severe using clinical classification. ECG parameters (RR interval, corrected QT (QTc) interval, P wave dispersion (Pwd)), and cardiac biomarkers (NT-proBNP and Troponin I) were significantly higher in cases than in control (p= 0.015, 0.008, 0.002, <0.001, and <0.001 respectively). Cut-off values resulted from combined ROC curves analysis can predict blood Troponin I more than 0.05 ng/ml and NT-proBNP more than 125 pg/ ml (with 88% and 84% accuracy respectively). In addition, two regression equations were developed using all studied ECG parameters to predict Troponin I and NT-proBNP (with 68% and 43% accuracy respectively). RR average, PR average, QRS average, QTd, QTc, and Pwd could be used to predict Troponin I and NT-proBNP levels with good accuracy in carbon monoxide poisoning patients.

A brief history of carbon monoxide and its therapeutic origins

It is estimated that 10% of carbon throughout the cosmos is in the form of carbon monoxide (CO). Earth's earliest prebiotic atmosphere included the trinity of gasotransmitters CO, nitric oxide (NO), and hydrogen sulfide (H₂S), for which all of life has co-evolved with. The history of CO can be loosely traced to mythological and prehistoric origins with rudimentary understanding emerging in the middle ages. Ancient literature is focused on CO's deadly toxicity which is understandable in the context of our primitive relationship with coal and fire. Scientific inquiry into CO appears to have emerged throughout the 1700s followed by chemical and toxicological profiling throughout the 1800s. Despite CO's ghastly reputation, several of the 18th and 19th century scientists suggested a therapeutic application of CO. Since 2000, the fundamental understanding of CO as a deadly nuisance has undergone a paradigm shift such that CO is now recognized as a neurotransmitter and viable pharmaceutical candidate. This review is intended to provide a brief history on the trace origins pertaining to endogenous formation and therapeutic application of CO.

Comparison of CFD and Multizone Modeling from Contaminant Migration from a Household Gas Furnace

In Central and Eastern Europe, a growing popularity of gas heaters as the main source of heat and domestic hot water can be observed. This is the result of new laws and strategies for funding that have been put in place to encourage households to stop using coal and replace it with cleaner energy sources. However, there is a growing concern that gas furnaces are prone to malfunction and can be a threat to occupants through CO (carbon monoxide) generation. To see how a faulty gas furnace with a clogged exhaust may affect a household, a series of multizone and computational fluid dynamics (CFD) simulations were carried out using the CONTAM software and CFD0 editor created by the National Institute of Standards and Technology (NIST). The simulations presented different placements of the furnace and ventilation outlet in an attached garage. The results showed how the placement influenced contaminant migration and occupant exposure to CO. It changed the amount of CO that infiltrated to the attached house and influenced occupant exposure. The results may be used by future users to minimize the risk of CO poisoning by using the proper natural ventilation methods together with optimal placement of the header in the household.