Cardiovascular manifestations of moderate to severe carbon monoxide poisoning

Practical Recommendations for the Evaluation and Management of Cardiac Injury Due to Carbon Monoxide Poisoning

Carbon monoxide (CO) is a relatively frequent cause of poisoning evaluated in emergency departments. The risk of neurologic injuries, such as cognitive, psychological, vestibular, and motor deficits, is 25% to 50%. However, the risk of cardiac injuries should also be considered. Among patients with CO poisoning, the mortality in patients with myocardial injury is approximately 3 times greater than that in patients without myocardial injury. In large-scale studies, up to 69.2% of patients with acute CO poisoning exhibiting elevated troponin I levels and no underlying cardiovascular illnesses had late gadolinium enhancement on cardiac magnetic resonance, suggesting covert CO-induced myocardial fibrosis. Myocardial damage can be evaluated using electrocardiography, echocardiography, computed tomography, and cardiac magnetic resonance. This paper offers recommendations for cardiac evaluations based on our collective experience of managing >2,000 cases of acute CO poisoning with supporting information taken from peer-reviewed published reports on CO poisoning.

Risk of lung diseases in patients with previous carbon monoxide poisoning: a nationwide population-based cohort study in the Republic of Korea

INTRODUCTION

Carbon monoxide poisoning is associated with severe damage to various organs. In this study, we aimed to determine if previous carbon monoxide poisoning was associated with an increased risk of lung diseases.

METHODS

The study population was derived from the National Health Insurance Service database of Korea between 1 January 2002 and 31 December 2021. Adults with carbon monoxide poisoning, with at least one visit to medical facilities between 2002 and 2021, were included. For comparison, an equal number of matched controls with the same index date were selected from the database.

RESULTS

A total of 28,618 patients with carbon monoxide poisoning and 28,618 matched controls were included in this study. Approximately 42.8 per cent of the patient and control groups were female, with a mean age of 51.3 years. In patients with carbon monoxide poisoning, there was a significant increase in the risk of lung cancer (adjusted hazard ratio, 1.84; 95 per cent confidence interval, 1.42-2.39; P < 0.001), chronic obstructive pulmonary disease (adjusted hazard ratio, 1.60; 95 per cent confidence interval, 1.36-1.89; P < 0.001), pulmonary tuberculosis (adjusted hazard ratio, 1.46; 95 per cent confidence interval, 1.13-1.88; P = 0.003), and non-tuberculous mycobacterial infection (adjusted hazard ratio, 1.54; 95 per cent confidence interval, 1.01-2.36; P = 0.047).

DISCUSSION

In this retrospective cohort study, previous carbon monoxide poisoning was associated with an increased risk of lung cancer, chronic obstructive pulmonary disease, pulmonary tuberculosis, and non-tuberculous mycobacterial infection. Further studies are needed to confirm such an association in other populations and the risk of lung diseases due to the toxic effect of carbon monoxide from different sources.

CONCLUSIONS

Previous carbon monoxide poisoning was associated with an increased risk of lung diseases, but the relative importance of the causes and sources of exposure was not known. The long-term management of survivors of acute carbon monoxide poisoning should include monitoring for lung cancer, chronic obstructive pulmonary disease, pulmonary tuberculosis, and non-tuberculous mycobacterial infection.

The Relationship between Fragmented QRS and Myocardial Injury in Patients with Acute Carbon Monoxide Poisoning

Background and Objectives: Carbon monoxide (CO) intoxication is one of the most common causes of poisoning-related deaths and complications. Myocardial injury is an important complication of CO poisoning. In our study, we aimed to evaluate the relationship between the presence and prevalence of fragmented QRS (fQRS) and myocardial injury in patients with CO intoxication. Materials and Methods: We retrospectively evaluated patients who presented to the emergency department of our tertiary care center with CO intoxication between January 2020 and December 2023. In our study, we performed subgroup analyses according to the presence of myocardial injury and fQRS. We evaluated the parameters and risk factors associated with myocardial injury. Results: Myocardial injury was detected in 44 patients, and fQRS was detected in 38 patients. In the myocardial injury (+) group, the fQRS rate was 38.6%, and the median number of leads with fQRS was 3 (2-6) and was significantly higher than in the myocardial injury (-) group (p < 0.001). We found that carboxyhemoglobin had a significant positive correlation with troponin (p = 0.001) and pro-B-type natriuretic peptide (proBNP) (p = 0.009). As a result of multivariate analysis, we determined that age, creatinine, proBNP, fQRS, and ≥3 leads with fQRS are independent risk factors for myocardial injury. Conclusions: Myocardial injury in CO intoxication patients is associated with proBNP, the presence of fQRS, and the number of leads with fQRS. Age, creatinine level, proBNP, the presence of fQRS, and ≥3 leads with fQRS are independent risk factors for myocardial injury in patients with CO intoxication.

Carbon Monoxide Poisoning: From Microbes to Therapeutics

Carbon monoxide (CO) poisoning leads to 50,000-100,000 emergency room visits and 1,500-2,000 deaths each year in the United States alone. Even with treatment, survivors often suffer from long-term cardiac and neurocognitive deficits, highlighting a clear unmet medical need for novel therapeutic strategies that reduce morbidity and mortality associated with CO poisoning. This review examines the prevalence and impact of CO poisoning and pathophysiology in humans and highlights recent advances in therapeutic strategies that accelerate CO clearance and mitigate toxicity. We focus on recent developments of high-affinity molecules that take advantage of the uniquely strong interaction between CO and heme to selectively bind and sequester CO in preclinical models. These scavengers, which employ heme-binding scaffolds ranging from organic small molecules to hemoproteins derived from humans and potentially even microorganisms, show promise as field-deployable antidotes that may rapidly accelerate CO clearance and improve outcomes for survivors of acute CO poisoning.

Carbon monoxide and prognosis in smokers hospitalised with acute cardiac events: a multicentre, prospective cohort study

Background

Smoking cigarettes produces carbon monoxide (CO), which can reduce the oxygen-carrying capacity of the blood. We aimed to determine whether elevated expiratory CO levels would be associated with a worse prognosis in smokers presenting with acute cardiac events.

Methods

From 7 to 22 April 2021, expiratory CO levels were measured in a prospective registry including all consecutive patients admitted for acute cardiac event in 39 centres throughout France. The primary outcome was 1-year all-cause death. Initial in-hospital major adverse cardiac events (MAE; death, resuscitated cardiac arrest and cardiogenic shock) were also analysed. The study was registered at ClinicalTrials.gov (NCT05063097).

Findings

Among 1379 patients (63 ± 15 years, 70% men), 368 (27%) were active smokers. Expiratory CO levels were significantly raised in active smokers compared to non-smokers. A CO level >11 parts per million (ppm) found in 94 (25.5%) smokers was associated with a significant increase in death (14.9% for CO > 11 ppm vs. 2.9% for CO ≤ 11 ppm; p < 0.001). Similar results were found after adjustment for comorbidities (hazard ratio [HR] [95% confidence interval (CI)]): 5.92 [2.43-14.38]) or parameters of in-hospital severity (HR 6.09, 95% CI [2.51-14.80]) and propensity score matching (HR 7.46, 95% CI [1.70-32.8]). CO > 11 ppm was associated with a significant increase in MAE in smokers during initial hospitalisation after adjustment for comorbidities (odds ratio [OR] 15.75, 95% CI [5.56-44.60]) or parameters of in-hospital severity (OR 10.67, 95% CI [4.06-28.04]). In the overall population, CO > 11 ppm but not smoking was associated with an increased rate of all-cause death (HR 4.03, 95% CI [2.33-6.98] and 1.66 [0.96-2.85] respectively).

Interpretation

Elevated CO level is independently associated with a 6-fold increase in 1-year death and 10-fold in-hospital MAE in smokers hospitalized for acute cardiac events.

Funding

Grant from Fondation Coeur & Recherche.

Clinical and Echocardiographic Predictors for the Presence of Late Gadolinium Enhancement on Cardiac Magnetic Resonance Imaging in Patients with Carbon Monoxide Poisoning

Late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMRI) reflects the burden of myocardial damage in carbon monoxide (CO) poisoning. This study aimed to identify the clinical and echocardiographic parameters that can predict myocardial LGE on CMRI in CO poisoning. This prospective observational study included patients who presented with acute CO poisoning and elevated troponin I and underwent echocardiography and CMRI to identify myocardial damage at a tertiary university hospital between August 2017 and May 2019 and August 2020 and July 2022. Based on the CMRI findings, participants were categorized into LGE and non-LGE groups. The median age of the 155 patients was 51.0 years, and 98 (63.2%) were males. Median times from emergency department arrival to either CMRI or echocardiography were 3.0 days each. The LGE group included 99 (63.9%) patients with LGE positivity on CMRIs. Time from rescue to hyperbaric oxygen therapy >4 h (odds ratio (OR): 3.31, 95% confidence interval (CI): 1.28-8.56, p = 0.01); serum lactate levels >2 mmol/L (OR: 2.62, 95% CI: 1.20-5.73, p = 0.02); and left ventricular global longitudinal strain >-16% (OR: 2.95, 95% CI: 1.35-6.47, p = 0.007) were significant predictors of LGE positivity. The area under the curve of these predictors was 0.711. Our prediction model, which combines the clinical parameters with left ventricular global longitudinal strain, may be helpful in the early detection of LGE positivity.

Predicting acute brain lesions on magnetic resonance imaging in acute carbon monoxide poisoning: a multicenter prospective observational study

An acute brain lesion (ABL) identified by brain magnetic resonance imaging (MRI) after acute carbon monoxide (CO) poisoning is a strong prognostic factor for the development of delayed neuropsychiatric syndrome (DNS). This study aimed to identify predictors of ABLs on MRI in patients with acute CO poisoning. This was a multicenter prospective registry-based observational study conducted at two tertiary hospitals. A total of 1,034 patients were included. Multivariable logistic regression analysis showed that loss of consciousness (LOC) (adjusted odds ratio [aOR] 2.68, 95% Confidence Interval [CI]: 1.49-5.06), Glasgow Coma Scale (GCS) score < 9 (aOR 2.41, 95% CI: 1.49-3.91), troponin-I (TnI) (aOR 1.22, 95% CI: 1.08-1.41), CO exposure duration (aOR 1.09, 95% CI: 1.05-1.13), and white blood cell (WBC) (aOR 1.05, 95% CI: 1.01-1.09) were independent predictors of ABLs on MRI. LOC, GCS score, TnI, CO exposure duration, and WBC count can be useful predictors of ABLs on MRI in patients with acute CO poisoning, helping clinicians decide the need for an MRI scan or transfer the patient to an appropriate institution for MRI or hyperbaric oxygen therapy.

Carbon monoxide intoxication with a CO-Hb of 30% while smoking waterpipe: a case report

Carbon monoxide (CO) poisoning is a significant public health issue and a considerable economic burden in developed countries. While the majority of non-fire-related CO poisonings are attributed to gas heating, there are several other less recognized sources that should be considered in the initial differential diagnosis.The patient in this case was a 21-year-old who experienced a brief episode of loss of consciousness and was subsequently admitted to the Emergency department. Upon evaluation, the patient was diagnosed with CO poisoning, which necessitated hyperbaric oxygen therapy to mitigate the effects of this toxic exposure.Despite exhibiting harmful symptoms initially, the patient stated in a phone interview two and a half years post-incident that they have not experienced any enduring effects such as cardiac arrhythmia or concentration deficits. While their understanding of the risks associated with waterpipe smoking has increased, it has not influenced any major changes in their waterpipe smoking habits.

The Clinical Association between Carbon Monoxide Poisoning and Myocardial Injury as Measured by Elevated Troponin I Levels

Carbon monoxide (CO) poisoning accounts for over 50,000 estimated emergency room visits and approximately 1200 deaths per year in the US. Despite the high prevalence, there is a paucity of data looking at the association between laboratory biomarkers and clinical outcomes. Our study investigates the association between myocardial injury as assessed by increased troponin levels and its effect on in-hospital outcomes in CO poisoning. A total of 900 sequential charts of patients presenting with CO poisoning between 1 January 2012, and 31 August 2019, at our tertiary center with regional hyperbaric chamber and burn unit, were reviewed. Of the 900, a total of 488 patients had elevated carboxyhemoglobin levels. Of these 488 patients, 119 (24.4%) also had blood troponin levels measured. Patients were stratified based on the presence or absence of myocardial injury as evidenced by highly sensitive serum troponin I (TnI) level > 0.5 ng/mL to determine if a correlation exists relating to myocardial injury and risk of major adverse events. Mean age was 51.2 years, 58.8% were males, 35.3% were non-White, and 10.1% were intentional CO poisonings. Comorbidities included hypertension: 37%, diabetes: 21%, smoking: 21%, hyperlipidemia: 17.6%, coronary artery disease: 11.8%, asthma: 5.9%, heart failure: 5%, atrial fibrillation: 4.2%, and chronic obstructive pulmonary disease: 4.2%. Myocardial injury occurred in 22 patients (18.5%) and was associated with increased likelihood of requiring intensive care admission (54.5% vs. 20.6%, p = 0.002) and intubation (40.9% vs. 14.4%, p = 0.008). TnI elevation was associated with higher in-hospital mortality (p = 0.008, OR 21.3) compared to patients without TnI elevation. Older age was independently associated with increased in-hospital mortality (p = 0.03, OR 1.08). When controlling for age, in-hospital mortality remained statistically significant (p = 0.01, OR 21.37). No significant difference was found with respect to age, comorbidities, gender, race, ethnicity, or hospital length of stay in patients with and without myocardial injury. Myocardial injury induced by CO exposure occurs frequently and adversely affects clinical outcomes. Further research is needed to help guide physicians in the management of CO poisoning and associated myocardial injury to improve patient outcomes.

Acute Cardiomyopathy and Delayed Neuropsychiatric Sequelae of Carbon Monoxide Poisoning: A Case Report

Carbon monoxide (CO) is an odorless and colorless gas that is formed by the combustion of hydrocarbon. CO poisoning is not an uncommon phenomenon that can have serious consequences for morbidity and mortality. The most frequent causes of accidental poisoning include smoke inhalation from fires, malfunctioning heating devices, smoke from motor vehicles in a poorly ventilated or enclosed space, and electrical cable fires. CO has a higher affinity to hemoglobin than oxygen leading to the formation of carboxyhemoglobin. It impairs the oxygen transport and cytochrome chain which, therefore, leads to further cellular and immunological changes. Here, we present a case of CO poisoning resulting in combined cardiac and neuropsychiatric complications.

Atrial Fibrillation and Silent Coronary Spasm Complicating Severe Carbon Monoxide Poisoning

Carbon monoxide (CO) poisoning is a toxicological emergency and may be responsible for more than half of all fatal poisonings worldwide. Serious effects of CO are frequently seen in the brain and heart as well as other organs that are particularly sensitive to hypoxia. Cardiac manifestations include dysrhythmias, myocardial infarction, and even cardiac arrest. Even in mild cases of CO poisoning with absent chest pain, the emergency physician should evaluate features of myocardial injury, as this can serve as a predictor of mortality and morbidity. A case of a young, healthy man with severe CO poisoning presented with atrial fibrillation (AF) and vasospastic angina, and he was managed successfully with high-flow oxygen.

Unexpected carboxyhemoglobin half-life during cardiopulmonary resuscitation: a case report

BACKGROUND

Cardiac arrest (CA) following CO poisoning (CO-induced CA) exposes patients to an extremely high risk of mortality and remains challenging to treat effectively. Terminal carboxyhemoglobin elimination half-life (COHbt_1/2) is critically affected by ventilation, oxygen therapy, and cardiac output, which are severely affected conditions in cases of CA.

CASE PRESENTATION

Asystole occurred in an 18-year-old woman after unintentional exposure to CO in her bathroom. Cardiopulmonary resuscitation (CPR) was started immediately, including mechanical ventilation with a fraction of inspired oxygen (FiO₂) of 1.0 and external chest compressions with a LUCAS® device. CPR was stopped after 101 min, as it was unsuccessful. During this period, we calculated a COHbt_1/2 of 40.3 min using a single compartmental model.

CONCLUSIONS

This result suggests that prolongation of CPR time needed to back COHb at 10%, a level more compatible with successful return of spontaneous circulation (ROSC), could be compatible with a realistic CPR time. Calculating COHbt_1/2 during CPR may help with decision-making regarding the optimal duration of resuscitation efforts and further with HBO₂ or ECLS. Further evidence-based data are needed to confirm this result.

Association between air pollution exposure and coronary heart disease hospitalization in a humid sub-tropical region of China: A time-series study

Objective

Emerging evidence has highlighted the possible links of environmental pollution with several cardiovascular diseases (CVDs). The current study aimed to explore the impact of short-term air pollution exposure on CHD hospitalization in Hefei.

Methods

Data about the daily number of CHD admissions (from 2014 to 2021) were retrieved from the First Affiliated Hospital of Anhui Medical University. Air pollutants and meteorological data were obtained from the China Environmental Monitoring Station and the China Meteorological Data Service Center, respectively. The correlation between air pollution and CHD hospitalization was assessed using distributed lag non-linear model (DLNM) and Poisson generalized linear regression.

Results

In the single-pollutant model, NO₂, O₃, and CO strongly correlated with CHD hospitalization rate. Specifically, exposure to NO₂ (lag0, relative risk [RR]: 1.013, 95%CI: 1.002-1.024, per 10 μg/m³ increase) and CO (lag13, RR: 1.035, 95%CI: 1.001-1.071, per 1 μg/m³ increase) revealed a positive correlation with an increased rate of CHD hospitalization. Interestingly, O₃ had a protective association with hospitalization of CHD (lag0, RR: 0.993, 95%CI: 0.988-0.999, per 10 μg/m³ increase). Similar results, to those of the single-pollutant model, were revealed following verification using two-pollutant models. Subgroup analyses indicated that young people, women, and people in hot seasons were more susceptible to NO₂ exposure, while the elderly, women, and people in cold seasons were more susceptible to O₃. Furthermore, the elderly were more susceptible to CO exposure.

Conclusion

Overall, exposure to NO₂ and CO increases the rate of CHD hospitalization, but exposure to O₃ shows a protective association with the rate of CHD hospitalization. Therefore, early preventive measures against air pollutants should be applied to protect vulnerable patients with CHD.

Das Shishaphänomen: Gefahren einer unterschätzten Droge

Der Konsum von Wasserpfeifen hat in den letzten Jahren v. a. bei Jugendlichen deutlich zugenommen. Die Risiken und Gefahren werden nicht nur bei den Konsumenten unterschätzt. Neben einer besseren Aufklärung der potenziellen Nutzergruppe sind für die im Gesundheitswesen Tätigen eine Sensibilisierung für mögliche Komplikationen und eine genaue Kenntnis des Vorgehens bei möglicher Intoxikation durch Kohlenmonoxid nach Shishagebrauch unerlässlich.

Eine unklare Bewusstseinsstörung ist ein häufiger Einlieferungsgrund in die Notaufnahme. Durch gezielte Anamnese und genauen Blick auf die Blutgasanalyse konnte bei einem jugendlichen Patienten eine Kohlenstoffmonoxidintoxikation nach Shishakonsum als Ursache gefunden werden. Unter intensivmedizinischer Überwachung und Sauerstoffgabe verlief dieser Fall komplikationslos.

Donor heart selection: Evidence-based guidelines for providers

The proposed donor heart selection guidelines provide evidence-based and expert-consensus recommendations for the selection of donor hearts following brain death. These recommendations were compiled by an international panel of experts based on an extensive literature review.

Rare Causes of Acute Coronary Syndrome: Carbon Monoxide Poisoning

Acute coronary syndrome (ACS) is a spectrum of clinical and paraclinical disorders arising from an imbalance of oxygen demand and supply to the myocardium. The most common cause is atherosclerosis; however, other rare causes such as carbon monoxide (CO) poisoning should be considered. Through tissue hypoxia and direct cell injury, CO poisoning can lead to a broad spectrum of cardiac disorders, especially ACS. Materials and Methods. We have conducted a retrospective study in the Toxicology Department of Saint Spiridon Emergency University Hospital, including all patients admitted through the emergency department with CO poisoning. We divided the cohort into event group (myocardial injury) and non-event group (patients without myocardial injury) and performed a subset analysis of the former. Results. A total of 65 patients were included, 22 in the event and 43 in the non-event group. The severity of poisoning did not correlate with myocardial injury; however, 50% of the event group had severe poisoning with carboxyhaemoglobin ≥ 20%. Cardiac enzyme markers (troponin and creatin-kinase MB) had a statistically significant increase in the event group compared to the non-event group (p < 0.05). Most of the patients in the STEMI (50%) and NSTEMI (66.7%) groups had severe CO intoxication. The STEMI group had a mean age of 27.7 years old and no comorbidities. Conclusions. Myocardial injury can develop in CO poisoning irrespective of the severity of poisoning, and it can be transient, reversible, or permanent. Our study introduces new information on adverse cardiac events in patients with CO poisoning, focusing on the ACS. We found that the severity of CO poisoning plays an important role in developing myocardial injury, as 50% of patients in the event group were severely intoxicated. While in-hospital mortality in our study was low, further prospective studies should investigate the long-term mortality in these patients.

Effect of early intervention on short-term prognosis of patients with myocardial injury induced by acute carbon monoxide poisoning

AIM

This study aimed to investigate the effect of early intervention on the short-term prognosis of patients with myocardial injury induced by acute carbon monoxide poisoning (ACOP).

METHODS AND RESULTS

We performed a retrospective cohort study of 139 patients admitted to the hospital for ACOP-induced acute toxic cardiopathy. Compared with the mild and moderate toxic cardiopathy group, the severe toxic cardiopathy group has significantly increased coma time, acute physiology and chronic health status (APACHE) II score, and the length of hospital stay and significantly reduced proportion of patients with immediate endotracheal intubation and early admission to intensive care unit (ICU) (all P < 0.05). The cardiac troponin I (cTnI) levels and corrected QT dispersion (QTcd) duration in three patient groups were significantly higher (all P < 0.05) than those in the control group, with the highest in the severely toxic heart disease group. Serum cTnI level and QTcd duration were two independent predictors of myocardial injury in ACOP patients. There was a positive correlation between the APACHE II score and serum cTnI level/QTcd duration at admission. The sensitivities of cTnI and QTcd at admission to diagnose serious cardiovascular events were 78.6% and 85.7%, respectively, and the specificities were both 75%.

CONCLUSIONS

Acute carbon monoxide poisoning patients with myocardial injury need to be admitted to the hospital as early as possible. For patients with severe hypoxia, an artificial airway should be established as early as possible, and patients should be admitted to the monitoring ward to stabilize their condition at the early stage of poisoning. Meanwhile, changes in QTcd, serum cTnI, and creatine kinase-MB (CK-MB) should be closely observed.

Potential markers for predicting delayed encephalopathy in patients with acute carbon monoxide poisoning

BACKGROUND

Acute carbon monoxide poisoning (ACOP) commonly results in delayed neuropsychiatric sequelae (DNS). Currently, there are no reliable predictors. The aim of this article is to establish a practical model for predicting the development of delayed encephalopathy clinically.

METHODS

Retrospective analysis of clinical data were performed at a single institution for the past 6 years. 107 patients with ACOP were recruited, of who 67 developed DNS and 40 did not. Clinical characteristics of the patients were analyzed between the two groups. The risk factors associated with DNS development were screened to identify the potential markers for predicting DNS. A predictive model was then built, and the receiver operating characteristic (ROC) curve analysis was used to assess its predictive ability.

RESULTS

There were significant differences in 13 clinical features between the two groups. Four potential markers were identified. They were age, source of CO, Glasgow Coma Scale score and the initiation of HBOT. The potential predictive model showed an area under the curve (AUC) of 0.93 in the training set and 0.97 in the testing set.

CONCLUSIONS

Our model could calculate the probability of DNS after acute CO poisoning.

S2k guideline diagnosis and treatment of carbon monoxide poisoning

Carbon monoxide (CO) can occur in numerous situations and ambient conditions, such as fire smoke, indoor fireplaces, silos containing large quantities of wood pellets, engine exhaust fumes, and when using hookahs. Symptoms of CO poisoning are nonspecific and can range from dizziness, headache, and angina pectoris to unconsciousness and death. This guideline presents the current state of knowledge and national recommendations on the diagnosis and treatment of patients with CO poisoning. The diagnosis of CO poisoning is based on clinical symptoms and proven or probable exposure to CO. Negative carboxyhemoglobin (COHb) levels should not rule out CO poisoning if the history and symptoms are consistent with this phenomenon. Reduced oxygen-carrying capacity, impairment of the cellular respiratory chain, and immunomodulatory processes may result in myocardial and central nervous tissue damage even after a reduction in COHb. If CO poisoning is suspected, 100% oxygen breathing should be immediately initiated in the prehospital setting. Clinical symptoms do not correlate with COHb elimination from the blood; therefore, COHb monitoring alone is unsuitable for treatment management. Especially in the absence of improvement despite treatment, a reevaluation for other possible differential diagnoses ought to be performed. Evidence regarding the benefit of hyperbaric oxygen therapy (HBOT) is scant and the subject of controversy due to the heterogeneity of studies. If required, HBOT should be initiated within 6 h. All patients with CO poisoning should be informed about the risk of delayed neurological sequelae (DNS).

Air Pollution and Cardiac Arrhythmias: From Epidemiological and Clinical Evidences to Cellular Electrophysiological Mechanisms

Cardiovascular disease is the leading cause of death worldwide and kills over 17 million people per year. In the recent decade, growing epidemiological evidence links air pollution and cardiac arrhythmias, suggesting a detrimental influence of air pollution on cardiac electrophysiological functionality. However, the proarrhythmic mechanisms underlying the air pollution-induced cardiac arrhythmias are not fully understood. The purpose of this work is to provide recent advances in air pollution-induced arrhythmias with a comprehensive review of the literature on the common air pollutants and arrhythmias. Six common air pollutants of widespread concern are discussed, namely particulate matter, carbon monoxide, hydrogen sulfide, sulfur dioxide, nitrogen dioxide, and ozone. The epidemiological and clinical reports in recent years are reviewed by pollutant type, and the recently identified mechanisms including both the general pathways and the direct influences of air pollutants on the cellular electrophysiology are summarized. Particularly, this review focuses on the impaired ion channel functionality underlying the air pollution-induced arrhythmias. Alterations of ionic currents directly by the air pollutants, as well as the alterations mediated by intracellular signaling or other more general pathways are reviewed in this work. Finally, areas for future research are suggested to address several remaining scientific questions.

Carbon Monoxide Poisoning and Developing Ischemic Heart Disease: A Nationwide Population-Based Nested Case-Control Study

Although there are several case reports showing that carbon monoxide (CO) poisoning causes ischemic heart disease (IHD), no large-scale epidemiological studies have shown a significant association between the two. To investigate the association between CO poisoning and IHD, a nested case-control study of 28,113 patients who experienced CO poisoning and 28,113 controls matched by sex and age was performed using the nationwide health database of South Korea. Based on a conditional logistic regression, there was a significantly higher risk of IHD among the CO poisoning group than among the control group (adjusted hazard ratio [HR], 2.16; 95% confidence interval [CI], 1.87–2.49). The risk of IHD after CO poisoning was higher among the younger age group under 40 years (adjusted HR, 4.85; 95% CI, 3.20–7.35), and it was much greater among those with comorbidities (adjusted HR, 10.69; 95% CI, 2.41–47.51). The risk of IHD was the highest within the first two years after CO poisoning (adjusted HR, 11.12; 95% CI, 4.54–27.22). Even if more than six years had passed, the risk was still significantly higher than among the control group (adjusted HR, 1.55; 95% CI, 1.27–1.89). The analyses imply that CO poisoning is associated with an increased risk of IHD.

Risk of acute kidney injury among patients with carbon monoxide poisoning

ABSTRACT

There is a lack of evidence supporting the association between carbon monoxide (CO) poisoning and acute kidney injury (AKI). Hence, the present study aimed to evaluate the association between CO poisoning and AKI.From 2000 to 2011, we identified patients diagnosed with CO poisoning from the inpatient claims data. Patients aged below 20 years, who had a history of chronic kidney disease or end-stage renal disease before the index date and had incomplete medical information were excluded. Control patients without CO poisoning were randomly selected from all National Health Insurance beneficiaries, and the same exclusion criteria were used. The control group was frequency matched to patients with CO poisoning based on age, sex, and year of CO poisoning diagnosis. Cox proportional hazards regression analyses were conducted to assess the effects of CO poisoning on the risk of AKI. The hazard ratios and 95% confidence interval (CI) were calculated in the models.Compared with the control cohort, patients with severe CO poisoning were 3.77 times more likely to develop AKI (95% CI = 2.20-6.46), followed by those with less severe CO poisoning (adjusted hazard ratio = 2.21, 95% CI = 1.61-3.03).The findings of this nationwide study suggest an increased risk of AKI in patients with CO poisoning.

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.

Dying "from" or "with" COVID-19 during the Pandemic: Medico-Legal Issues According to a Population Perspective

There is still a lack of knowledge concerning the pathophysiology of death among COVID-19-deceased patients, and the question of whether a patient has died with or due to COVID-19 is still very much debated. In Italy, all deaths of patients who tested positive for SARS-CoV-2 are defined as COVID-19-related, without considering pre-existing diseases that may either contribute to or even cause death. Our study included nine subjects from two different nursing homes (Cases 1–4, Group A; Cases 5–9, Group B). The latter included patients who presumably died from CO poisoning due to a heating system malfunction. All subjects tested positive for COVID-19 both ante- and post-mortem and were examined using post-mortem computed tomography prior to autopsy. COVID-19 was determined to be a contributing cause in the deaths of four out of nine subjects (death due to COVID-19; i.e., pneumonia and sudden cardiac death). In the other five cases, for which CO poisoning was identified as the cause of death, the infection presumably had no role in exitus (death with COVID-19). In our attempt to classify our patients as dying with or due to COVID-19, we found the use of complete assessments (both histological analyses and computed tomography examination) fundamental.

Veno-venous extracorporeal blood phototherapy increases the rate of carbon monoxide (CO) elimination in CO-poisoned pigs

BACKGROUND AND OBJECTIVES

Carbon monoxide (CO) inhalation is the leading cause of poison-related deaths in the United States. CO binds to hemoglobin (Hb), displaces oxygen, and reduces oxygen delivery to tissues. The optimal treatment for CO poisoning in patients with normal lung function is the administration of hyperbaric oxygen (HBO). However, hyperbaric chambers are only available in medical centers with specialized equipment, resulting in delayed therapy. Visible light dissociates CO from Hb with minimal effect on oxygen binding. In a previous study, we combined a membrane oxygenator with phototherapy at 623 nm to produce a "mini" photo-ECMO (extracorporeal membrane oxygenation) device, which improved CO elimination and survival in CO-poisoned rats. The objective of this study was to develop a larger photo-ECMO device ("maxi" photo-ECMO) and to test its ability to remove CO from a porcine model of CO poisoning.

STUDY DESIGN/MATERIALS AND METHODS

The "maxi" photo-ECMO device and the photo-ECMO system (six maxi photo-ECMO devices assembled in parallel), were tested in an in vitro circuit of CO poisoning. To assess the ability of the photo-ECMO device and the photo-ECMO system to remove CO from CO-poisoned blood in vitro, the half-life of COHb (COHb-t_1/2 ), as well as the percent COHb reduction in a single blood pass through the device, were assessed. In the in vivo studies, we assessed the COHb-t_1/2 in a CO-poisoned pig under three conditions: (1) While the pig breathed 100% oxygen through the endotracheal tube; (2) while the pig was connected to the photo-ECMO system with no light exposure; and (3) while the pig was connected to the photo-ECMO system, which was exposed to red light.

RESULTS

The photo-ECMO device was able to fully oxygenate the blood after a single pass through the device. Compared to ventilation with 100% oxygen alone, illumination with red light together with 100% oxygen was twice as efficient in removing CO from blood. Changes in gas flow rates did not alter CO elimination in one pass through the device. Increases in irradiance up to 214 mW/cm² were associated with an increased rate of CO elimination. The photo-ECMO device was effective over a range of blood flow rates and with higher blood flow rates, more CO was eliminated. A photo-ECMO system composed of six photo-ECMO devices removed CO faster from CO-poisoned blood than a single photo-ECMO device. In a CO-poisoned pig, the photo-ECMO system increased the rate of CO elimination without significantly increasing the animal's body temperature or causing hemodynamic instability.

CONCLUSION

In this study, we developed a photo-ECMO system and demonstrated its ability to remove CO from CO-poisoned 45-kg pigs. Technical modifications of the photo-ECMO system, including the development of a compact, portable device, will permit treatment of patients with CO poisoning at the scene of their poisoning, during transit to a local emergency room, and in hospitals that lack HBO facilities.

Evaluation of the Cardioprotective Effect of Granulocyte Colony Stimulating Factor in Patients with Carbon Monoxide Poisoning

BACKGROUND

Carbon monoxide (CO), which is well known as silent killer, has many toxic effects on organs with high rate of metabolism such as heart and brain. CO-induced cardiotoxicity resulted in a wide range of disabilities including electrocardiogram (ECG) abnormalities, elevation in level of cardiac enzymes, arrhythmias, impairment of left ventricular and myocardial infarction (MI). Cardio-protective effects of Granulocyte colony-stimulating factor (G-CSF) on infarcted heart was proved previously in various reports.

OBJECTIVE

In this study, possible effect of G-CSF on cardiac function of patients with moderate to severe acute CO poisoning was investigated.

METHODS

Cardioprotective effects of G-CSF in CO-poisoned patients was evaluated through ECG, Holter monitoring, echocardiography, and biochemical studies. Continuous intravenous infusion of G-CSF (90 μg/kg) and normal saline were administered respectively to treatment and placebo groups.

RESULTS

The results demonstrated that in moderate to severe CO poisoning, myocardial injury is common. ECG changes (e.g., ST-segment and T-wave changes, QTC), cardiac arrhythmias (e.g., heart blocks and ventricular arrhythmias), serum level of Troponin I, left ventricular ejection fraction were determined after G-CSF administration. Frequencies of ST depression, inversion or flatting of T wave and QTC in ECG were significantly reduced after G-CSF treatment. In addition, incidence of cardiac arrhythmias due to CO poisoning were reduced after G-CSF treatment. However, G-CSF did not exert protective effects on TPI level and function of left ventricular in CO-poisoned patients.

CONCLUSION

GCSF could probably reduce CO-induced cardiac ischemia in patients with acute CO poisoning.

CLINICAL TRIAL REGISTRATION

The trial protocol was registered in the Iranian Registry of Clinical Trials (http://www.irct.ir) registry (Irct ID: IRCT201607232083N7).

Prevalence of myocardial injury requiring percutaneous coronary intervention after acute carbon monoxide poisoning

OBJECTIVE

More than one-third of patients with moderate to severe acute carbon monoxide (CO) poisoning had myocardial injury. However, the ratio of acute CO patients necessitating percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG) remains unknown. This study aimed to examine the prevalence of myocardial injury requiring PCI or CABG in patients with CO poisoning.

METHODS

This was a nationwide retrospective cohort study, using the Japanese Diagnosis Procedure Combination inpatient database focusing on the period between 2010 and 2017. We extracted data on patients diagnosed with CO poisoning and determined the prevalence of cases presenting with myocardial injury requiring PCI or CABG.

RESULTS

We identified 9091 eligible patients. Within this patient pool, eight patients underwent PCI within 2 days of admission. No patients required CABG. The prevalence of subsequent PCI was 0.09% (8/9091). The patients who required PCI had a significantly higher median age than those who did not (75 vs. 52 years of age, respectively). Patients requiring PCI were older and were more likely to have underlying comorbidities such as hypertension and diabetes mellitus.

CONCLUSION

The present study reported a low prevalence of myocardial injury requiring PCI in acute CO poisoning patients. Although myocardial injury due to coronary artery occlusion would be a very rare presentation in the setting of acute CO poisoning, coronary occlusion should be taken into consideration for elderly patients and/or patients who have coronary risk factors.

Deterministic and Stochastic Cellular Mechanisms Contributing to Carbon Monoxide Induced Ventricular Arrhythmias

Chronic exposure to low levels of Carbon Monoxide is associated with an increased risk of cardiac arrhythmia. Microelectrode recordings from rat and guinea pig single isolated ventricular myocytes exposed to CO releasing molecule CORM-2 and excited at 0.2/s show repolarisation changes that develop over hundreds of seconds: action potential prolongation by delayed repolarisation, EADs, multiple EADs and oscillations around the plateau, leading to irreversible repolarisation failure. The measured direct effects of CO on currents in these cells, and ion channels expressed in mammalian systems showed an increase in prolonged late Na+, and a decrease in the maximal T- and L-type Ca++. peak and late Na+, ultra-rapid delayed, delayed rectifier, and the inward rectifier K+ currents. Incorporation of these CO induced changes in maximal currents in ventricular cell models; (Gattoni et al., J. Physiol., 2016, 594, 4193-4224) (rat) and (Luo and Rudy, Circ. Res., 1994, 74, 1071-1096) (guinea-pig) and human endo-, mid-myo- and epi-cardial (O'Hara et al., PLoS Comput. Biol., 2011, 7, e1002061) models, by changes in maximal ionic conductance reproduces these repolarisation abnormalities. Simulations of cell populations with Gaussian distributions of maximal conductance parameters predict a CO induced increase in APD and its variability. Incorporation of these predicted CO induced conductance changes in human ventricular cell electrophysiology into ventricular tissue and wall models give changes in indices for the probability of the initiation of re-entrant arrhythmia.

Increased Risk of Congestive Heart Failure Following Carbon Monoxide Poisoning

BACKGROUND

Carbon monoxide poisoning (COP) is an important public health issue around the world. It may increase the risk of myocardial injury, but the association between COP and congestive heart failure (CHF) remains unclear. We conducted a study incorporating data from epidemiological and animal studies to clarify this issue.

METHODS

Using the National Health Insurance Database of Taiwan, we identified patients with COP diagnosed between 1999 and 2012 and compared them with patients without COP (non-COP cohort) matched by age and the index date at a 1:3 ratio. The comparison for the risk of CHF between the COP and non-COP cohorts was made using Cox proportional hazards regression. We also established a rat model to evaluate cardiac function using echocardiography and studied the pathological changes following COP.

RESULTS

The 20 942 patients in the COP cohort had a higher risk for CHF than the 62 826 members in the non-COP cohort after adjusting for sex and underlying comorbidities (adjusted hazard ratio, 2.01 [95% CI, 1.74-2.32]). The increased risk of CHF persisted even after 2 years of follow-up (adjusted hazard ratio, 1.85 [95% CI, 1.55-2.21]). In the animal model, COP led to a decreased left ventricular ejection fraction on echocardiography and damage to cardiac cells with remarkable fibrotic changes.

CONCLUSIONS

Our epidemiological data showed an increased risk of CHF was associated with COP, which was supported by the animal study. We suggest close follow-up of cardiac function for patients with COP to facilitate early intervention and further studies to identify other long-term effects that have not been reported in the literature.

Myocardial Injury and Fibrosis From Acute Carbon Monoxide Poisoning: A Prospective Observational Study

OBJECTIVES

This study sought to evaluate the prevalence and patterns of late gadolinium enhancement (LGE) after carbon monoxide (CO) poisoning using cardiac magnetic resonance (CMR) imaging (CMRI) and transthoracic echocardiography (TTE).

BACKGROUND

In acute CO poisoning, cardiac injury can predict mortality. However, it remains unclear why increased mortality and cardiovascular events occur despite normalization of CO-induced elevated troponin I (TnI) and cardiac dysfunction.

METHODS

Patients with acute CO poisoning with elevated TnI were evaluated. CMRI was performed within 7 days of CO exposure and after 4 to 5 months. Patients were divided into LGE (n = 72; 69.2%) and no-LGE (n = 32; 30.8%) groups.

RESULTS

In the LGE group, 39.4%, 4.8%, and 25.0% of patients exhibited midwall, subendocardial, and right ventricular insertion point injury, respectively. Diffuse injury was observed in 22.1% of patients, and 67.6% of the 37 patients who underwent follow-up CMRI showed no interval change. On TTE, baseline left ventricular ejection fraction and global longitudinal strain were significantly deteriorated in the LGE group; serial TTE within 7 days indicated that only left ventricular global longitudinal strain remained significantly deteriorated. Three cases of mortality occurred in the LGE group during the 1-year follow-up.

CONCLUSIONS

The LGE prevalence in patients with acute CO poisoning with elevated TnI levels, with no underlying cardiovascular diseases and eligible for CMRI, was 69.2%; this proportion primarily comprised patients with a midwall injury. Of the 37 patients who underwent follow-up CMRI, most chronic phase images showed no interval change. Myocardial fibrosis detected on CMR images was related to acute myocardial dysfunction and subacute deterioration of myocardial strain on TTE. (Cardiac Magnetic Resonance Image in Acute Carbon Monoxide Poisoning; NCT04419298).

The Poisoned Heart: A Case of Takotsubo Cardiomyopathy Induced by Carbon Monoxide Poisoning

BACKGROUND

Carbon monoxide is a common environmental toxin, and some patients present with features of cardiac injury in addition to the noxious effects of carbon monoxide poisoning. A very small fraction of those have a transient left ventricular apical ballooning syndrome or Takotsubo cardiomyopathy, both terms are used to define a syndrome that affects the systolic function of the heart. It usually presents with elevated troponin levels with or without electrocardiographic changes. Cardiac angiograms generally illustrate coronary arteries without significant obstruction.

CASE REPORT

Here we report the curious case of a 37-year-old Hispanic man brought in for carbon monoxide poisoning, but found to have significantly elevated troponin levels. Echocardiogram demonstrated decreased ejection fraction of 35%. Left heart catheterization 2 days after admission revealed patent coronary arteries, improved ejection fraction to 45%, and wall motion abnormalities plus apical ballooning compatible with Takotsubo cardiomyopathy. The case is unusual because our patient differs from the classically defined elderly, postmenopausal female demographic, and did not experience an emotional crisis that could have provoked this series of events. It is also noteworthy for the fact that the only identifiable trigger was exposure to carbon monoxide. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Carbon monoxide poisoning is a common occurrence resulting in a multitude of annual emergency department visits. Given the known toxic effects of carbon monoxide poisoning on the heart, prompt cardiac workup is important to prevent overlooking a major, although rare, manifestation of carbon monoxide exposure.

Can indicators of myocardial damage predict carbon monoxide poisoning outcomes?

Background

Carbon monoxide causes electrical, functional, and morphological changes in the heart. It is unclear, however, whether the indicators of myocardial damage can predict the patient’s prognosis after carbon monoxide poisoning. This retrospective study aimed to investigate the relationship between the carboxyhemoglobin level and electrocardiographic (ECG) changes and whether the ECG changes and troponin I levels are related to the patient’s prognosis after carbon monoxide poisoning.

Methods

Carboxyhemoglobin, troponin I, and ECG parameters were measured in 70 patients with carbon monoxide poisoning. The QT and RR intervals were measured for each ECG lead in all patients, and the corrected QT interval and corrected QT dispersion were calculated.

Results

The correlation between the maximum corrected QT interval and the carboxyhemoglobin level was significant (P = 0.0072, R² = 0.1017), as were the relationships between QT dispersion and carboxyhemoglobin (P < 0.001, R² = 0.2358) and the corrected QT dispersion and carboxyhemoglobin (P < 0.001, R² = 0.2613). The multivariate logistic analysis showed that the significant predictors of sequential disability were corrected QT dispersion (P = 0.0042), and troponin I level (P = 0.0021).

Conclusions

Patients’ prognosis following carbon monoxide poisoning can be predicted based on corrected QT dispersion and the troponin I level. Patients with myocardial damage should be monitored not only for their cardiovascular outcome but also for their neurological outcome and their prognosis.

Diagnostic performance and optimal cut-off values of cardiac biomarkers for predicting cardiac injury in carbon monoxide poisoning

OBJECTIVE

This study aimed to compare the diagnostic performance of cardiac biomarkers and to evaluate the optimal cut-off values for echocardiographic cardiac injury prediction in patients with carbon monoxide (CO) poisoning.

METHODS

This retrospective observational cohort study included adult patients with acute CO poisoning. Patients who did not undergo transthoracic echocardiography, which was used to define patients with cardiac injury (ejection fraction <55%), were excluded. The area under the curve was used to evaluate diagnostic performance for cardiac injury prediction. Mann-Whitney U, chi-square, and Fisher exact tests were used to analyze data.

RESULTS

After excluding the 27 patients who did not undergo echocardiography, 114 patients were included in the study. Fifteen (13.2%) patients had cardiac injury. The area under the curve values for the B-type natriuretic peptide, creatine kinase-myocardial band, and troponin I were 0.711 (95% confidence interval [CI], 0.527-0.895; P=0.011), 0.766 (95% CI, 0.607-0.926; P=0.001), and 0.801 (95% CI, 0.647-0.955; P<0.001), respectively, with optimal cut-off values of 330 pg/mL, 10.1 ng/mL, and 0.455 ng/mL, respectively. The sensitivity, specificity, and positive and negative predictive values of troponin I were 67%, 91%, 53%, and 95%, respectively.

CONCLUSION

Troponin I showed the best diagnostic performance for predicting cardiac injury in patients with CO poisoning. A cut-off value of 0.455 ng/mL appeared optimal for cardiac injury prediction. However, further studies on cardiac biomarkers and other diagnostic tools in CO poisoning are needed given the low sensitivity of troponin I.

Myocardial Repolarization Parameters and Neutrophil-to-Lymphocyte Ratio are Associated with Cardiotoxicity in Carbon Monoxide Poisoning

The present study aims to examine the clinical values of complete blood count (CBC) bioindicators and corrected QT (QT_c), T_peak - T_end interval (T_p-e), T_{peak dispersion} (T_{p disp}), and T_p-e/QT ratio that are the parameters of myocardial repolarization (M-rep) for cardiotoxicity, which develops due to acute carbon monoxide (CO) intoxication in patients admitted to the emergency service. This retrospective, cross-sectional, observational, and single-center study was conducted between April and June 2019. Statistical analysis was performed using the SPSS 23.0 software. Data of 234 participants were analyzed. Of these, 54.9% (n = 129) were female. Neutrophil-to-lymphocyte ratio (NLR), QT_c, T_p-e values were significantly high in the CO intoxication group (p < 0.001, p < 0.001, and p < 0.001, respectively), whereas T_p-e/QT_c ratio was significantly lower in the CO intoxication group than that in the control group (p < 0.001). NLR, T_p-e, T_{p disp} values were significantly high in the myocardial injury (M-inj) group (p < 0.001, p = 0.003, and p = 0.018, respectively). Furthermore, T_p-e/QT_c ratio was significantly low in the M-inj group (p = 0.002). M-rep parameters and NLR are associated with CO intoxication and the development of M-inj. Moreover, these bioindicators and can provide clinicians an early indication of M-inj.

Usefulness of N-terminal pro-B-type natriuretic peptide (NT-ProBNP) as a marker for cardiotoxicity and comparison with echocardiography in paediatric carbon monoxide poisoning

OBJECTIVES

To demonstrate the usefulness of N-Terminal Pro-B-Type natriuretic peptide (NT-proBNP) as an early biomarker of carbon monoxide-induced myocardial injury in children. It also aimed to identify the correlation between NT-proBNP and left ventricular systolic dysfunction findings shown by echocardiography.

METHODS

Prospective, observational study conducted at a paediatric emergency department between October 2017 and April 2019 which involved children aged 0-17 years. The patients were divided into three groups based on severity; mild, moderate and severe groups. The patient characteristics, carboxyhaemoglobin, CK-MB Mass (CKMB-M), troponin-T, and NT-proBNP levels were measured, and echocardiography was performed and left ventricular ejection fraction was measured.

RESULTS

Sixty-nine patients and 60 healthy controls were included. Male gender, younger age, higher carboxyhaemoglobin levels, and altered mental status were found as independent predictors of carbon monoxide-induced myocardial injury. If the cut-off value for NT-proBNP level is >480 pg/ml, the sensitivity-specificity for decreased left ventricular ejection fraction, which is the strongest carbon monoxide-induced myocardial injury sign, were 100-96%, respectively. A high negative correlation was found between NT-proBNP levels and left ventricular ejection fraction (r = -0.769, p < 0.01) in the carbon monoxide poisoning group, and there was a positive correlation between the carboxyhaemoglobin and NT-proBNP levels (r = 0.583, p < 0.01).

CONCLUSION

Echocardiography is an ideal tool and very sensitive, but its routine use is limited due to its non-availability. An increased level of NT-proBNP (>480pg/ml) may be useful as an ideal biomarker for early detection of carbon monoxide-induced myocardial injury sign and reduced left ventricular ejection fraction which is the most crucial point in making a decision on hyperbaric oxygen therapy.

Silent Acute Coronary Syndrome in a Mild Carbon Monoxide Poisoning

Introduction: Carbon monoxide (CO) poisoning continues to be challenging in diagnosis and management. The complications related to CO poisoning are variable and unpredictable.

Case presentation: We present the case of a 73-year-old woman who was involved in an indoor fire. Although she was asymptomatic and had a low CO level, she developed an acute coronary syndrome. The condition of the patient recovered remarkably after treatment with oxygen supplementation and anti-ischemic drugs.

Conclusion: This case indicates that an acute coronary syndrome could represent a complication of CO poisoning even in asymptomatic patients with low levels of COHb.

Blood carboxyhemoglobin elimination curve, half-lifetime, and arterial-venous differences in acute phase of carbon monoxide poisoning in ovine smoke inhalation injury model

Smoke inhalation injury (SII) affects more than 50,000 people annually causing carbon monoxide (CO) poisoning. Although the increased blood level of carboxyhemoglobin (CO-Hb) is frequently used to confirm the diagnosis of SII, knowledge of its elimination in the acute phase is still limited. The aim of this study is to determine CO-Hb elimination rates and their differences in arterial (aCO-Hb) and mixed-venous (vCO-Hb) blood following severe SII in a clinically relevant ovine model. Forty-three chronically instrumented female sheep were subjected to SII (12 breaths, 4 sets) through tracheostomy tube under anesthesia and analgesia. After the SII, sheep were awakened and placed on a mechanical ventilator (FiO₂ = 1.0, tidal volume 12 mL/kg, and PEEP = 5cmH₂O) and monitored. Arterial and mixed-venous blood samples were withdrawn simultaneously for blood gas analysis at various time points to determine CO-HB half-lifetime and an elimination curve. The mean of highest aCO-Hb level during SII was 70.8 ± 13.9%. The aCO-Hb elimination curve showed an approximated exponential decay during the first 60 min. Per mixed linear regression model analysis, aCO-Hb significantly (p < 0.001) declined (4.3%/minute) with a decay constant lambda of 0.044. With this lambda, mean lifetime and half-lifetime of aCO-Hb were 22.7 and 15.7 min, respectively. The aCO-Hb was significantly lower compared to vCO-Hb at all-time points (0-180 min). To our knowledge, this is the first report describing CO-Hb elimination curve in the acute phase after severe SII in the clinically relevant ovine model. Our data shows that CO-Hb is decreasing in linear manner with supportive mechanical ventilation (0-60 min). The results may help to understand CO-Hb elimination curve in the acute phase and improvement of pre-hospital and initial clinical care in patients with CO poisoning.

Diagnosis of acute intoxications in critically ill patients: focus on biomarkers - part 2: markers for specific intoxications

In medical intensive care units, acute intoxications contribute to a large proportion of all patients. Epidemiology and a basic overview on this topic were presented in part one. The purpose of this second part regarding toxicological biomarkers in the ICU setting focuses on specific poisons and toxins. Following the introduction of anion and osmol gap in part one, it's relevance in toxic alcohols and other biomarkers for these poisonings are presented within this publication. Furthermore, the role of markers in the blood, urine and cerebrospinal fluid for several intoxications is evaluated. Specific details are presented, amongst others, for cardiovascular drug poisoning, paracetamol (acetaminophen), ethanol, pesticides, ricin and yew tree intoxications. Detailed biomarkers and therapeutic decision tools are shown for carbon monoxide (CO) and cyanide (CN^-) poisoning. Also, biomarkers in environmental toxicological situations such as mushroom poisoning and scorpion stings are presented.

Carbon monoxide intoxication in geriatric patients: How important are lactate values at admission?

PURPOSE

The aim of this study was to investigate the demographic and clinical characteristics and treatment modalities of elderly patients with carbon monoxide (CO) intoxication. The secondary aim was to evaluate the importance of plasma lactate values in the diagnosis of acute CO intoxication in geriatric patients.

METHODS

Data on geriatric patients who were admitted to the emergency department of Atatürk University Medical Faculty between January 2013 and April 2016 were analyzed retrospectively.

RESULTS

Of the 197 cases included in the study, 97 were in the intoxication group and 100 were in the control group; 82.5% of the intoxication cases had mild neurological symptoms and 17.5% had severe neurological symptoms. Carboxyhemoglobin levels were significantly higher in patients with severe neurological symptoms (p = 0.031). All patients with severe neurological symptoms received hyperbaric-oxygen therapy (p < 0.001). In the intoxication group, lactate levels were significantly higher than in the control group (p = 0.001). The specificity for lactate 4 mmol/L and above was found as 98.0% with a positive predictive value and negative predictive value of 84.5% and 53.3%, respectively.

CONCLUSION

High initial lactate levels may be a guide for cases with nonspecific symptoms in geriatric patients with suspected CO intoxication.

Atherosclerotic and Hypertensive Cardiovascular Disease are Associated with Death at Sublethal Carboxyhemoglobin Levels: A Postmortem Study

Residential fires are a significant cause for morbidity and mortality in the United States. Death is often the result of soot and smoke inhalation causing carbon monoxide (CO) toxicity. The approximate lethal level of carboxyhemoglobin (COHb) in healthy adults has been well described. However, a significant number of medical examiner cases involve infirmed decedents, often elderly, with complex cardiovascular disease burdens. It is well known that death in these cases will occur at sublethal levels of COHb; however, increased lethality has been largely documented via anecdotal experience and lacks quantification. Fifty-five cases were identified where death resulted from smoke and soot inhalation suffered in a residential fire. The control group, with no cardiovascular disease, had an age-adjusted mean COHb level of 61.6% at the time of death. Presence of hypertensive cardiovascular disease showed a 30% reduction in COHb (age-adjusted mean 43.2%), atherosclerotic disease showed a 33% reduction (age-adjusted mean 41.5%), and combined disease presentation accounted for 41% reduction (age-adjusted mean 36.3%). When controlling for age, atherosclerotic and hypertensive cardiovascular diseases were each associated with statistically significant decreases in COHb (p < 0.01). Increasing age was associated with decreased COHb levels at 2.8% per 10 years of life (p < 0.01), even when modeled with hypertensive and atherosclerotic disease. These findings carry important public health significance, as well as practical significance for the medical examiner when interpreting COHb levels in cases of suspected deaths due to smoke and soot inhalation.

Prognostic factors of carbon monoxide poisoning in Taiwan: a retrospective observational study

OBJECTIVES

To identify the risk factors related to the prognosis of carbon monoxide (CO)-poisoned patients in the hospital.

DESIGN

Retrospective observational study.

SETTING

Tri-Service General Hospital, Taiwan.

METHODS

We 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.

RESULTS

The 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.

CONCLUSION

We 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.

Electrostatic Potential Optimized Molecular Models for Molecular Simulations: CO, CO2, COS, H2S, N2, N2O, and SO2

Molecular simulations have been widely employed in the discovery of nanoporous materials, such as metal-organic frameworks (MOFs) and zeolite, for energy- and environment-related applications. To achieve simulation predictions with better accuracy, we herein present a collection of molecular models, including carbon monoxide (CO), carbon dioxide (CO₂), carbonyl sulfide (COS), hydrogen sulfide (H₂S), nitrogen (N₂), nitrous oxide (N₂O), and sulfur dioxide (SO₂). These models, denoted as electrostatic potential optimized molecular models (ESP-MMs), are systematically developed to not only reproduce experimental vapor-liquid equilibrium but also have accurate electrostatic potential representation surrounding the molecules. Our results show that, with accurate electrostatic potential representations, ESP-MMs can offer improved predictions in a variety of adsorption properties for porous materials, including MOFs with open-metal sites and all-silica zeolites. Specifically, by using ESP-MMs, the binding geometry and adsorption energy landscape can be well captured. This enables these models to be employed to unravel the fundamental mechanism of gaseous adsorption in materials of interest as well as to facilitate the parametrization of adsorbent-adsorbate interactions. We also demonstrate that, combined with generic force fields for adsorbents, ESP-MMs can offer reasonable predictions in adsorption isotherms. Although these ESP-MMs use a relatively simple and nonpolarizable potential form for the sake of efficiency and applicability, their accuracy has been extensively validated in this study. Furthermore, the set of Lennard-Jones potentials with static point charges adopted for ESP-MMs can be readily implemented in all available simulation packages. We anticipate that these ESP-MMs can largely facilitate future computational studies of porous materials for gas separation and removal.