Postmortem concentrations for total blood carbon monoxide (TBCO) as novel biomarker for carbon monoxide (CO) poisonings

Total Blood Carbon Monoxide (TBCO) showed promising results in improving accuracy of CO determinations in blood and presenting better stability to different storage conditions. Therefore, it was proposed as alternative biomarker to carboxyhemoglobin (COHb) for CO poisoning diagnosis. However, given that current interpretation reference values exist for COHb only, it is difficult to implement TBCO analysis in routine. Therefore, we aimed at determining TBCO reference values for postmortem CO poisoning cases. A previously validated method for TBCO analysis via gas chromatography-mass spectrometry was applied to cardiac, peripheral, cranial and spleen blood samples collected from 92 autopsies. Autopsy cases included 21 non-CO related and 71 CO-related cases with varying postmortem intervals (PMI). Statistical analyses were performed using statistical software R Studio. When comparing lower to higher PMI for non-CO related cases, no significant differences were found, which suggests that CO formation or degradation at low PMIs does not occur. Spleen blood showed potential as alternative matrix for CO determinations in cases with sample availability issues, but needs to be evaluated for CO positive cases. Results for cardiac blood in CO-related autopsies showed a positive correlation between COHb and TBCO values (R = 0.78). This value is lower than what is found in the literature, suggesting that even though COHb and TBCO are correlated, a potential underestimation of the true CO exposure might occur if only COHb values are taken into consideration. Samples were divided into CO exposure groups based on COHb concentrations and with the data obtained, classification into following TBCO concentration groups are proposed: no significant CO exposure case <6 µmol/mL, medium CO exposure case 6-20 µmol/mL, high CO exposure case >20µmol/mL. Even if a higher number of samples in each group would enable to increase the confidence, these results are very promising and highlight the importance of TBCO measurement.

Gray matter atrophy and white matter lesions burden in delayed cognitive decline following carbon monoxide poisoning

Gray matter (GM) atrophy and white matter (WM) lesions may contribute to cognitive decline in patients with delayed neurological sequelae (DNS) after carbon monoxide (CO) poisoning. However, there is currently a lack of evidence supporting this relationship. This study aimed to investigate the volume of GM, cortical thickness, and burden of WM lesions in 33 DNS patients with dementia, 24 DNS patients with mild cognitive impairment, and 51 healthy controls. Various methods, including voxel-based, deformation-based, surface-based, and atlas-based analyses, were used to examine GM structures. Furthermore, we explored the connection between GM volume changes, WM lesions burden, and cognitive decline. Compared to the healthy controls, both patient groups exhibited widespread GM atrophy in the cerebral cortices (for volume and cortical thickness), subcortical nuclei (for volume), and cerebellum (for volume) (p < .05 corrected for false discovery rate [FDR]). The total volume of GM atrophy in 31 subregions, which included the default mode network (DMN), visual network (VN), and cerebellar network (CN) (p < .05, FDR-corrected), independently contributed to the severity of cognitive impairment (p < .05). Additionally, WM lesions impacted cognitive decline through both direct and indirect effects, with the latter mediated by volume reduction in 16 subregions of cognitive networks (p < .05). These preliminary findings suggested that both GM atrophy and WM lesions were involved in cognitive decline in DNS patients following CO poisoning. Moreover, the reduction in the volume of DMN, VN, and posterior CN nodes mediated the WM lesions-induced cognitive decline.

Two similar carbon monoxide poisoning cases with different outcomes: evidence from longitudinal fMRI

Prognosis after carbon monoxide (CO) poisoning is difficult to assess using structural images. Functional connectivity provided by functional magnetic resonance imaging (fMRI) may explain the mechanism of differential prognosis. We report here two cases of carbon monoxide poisoning with simultaneous coma. They were nearly normal on days 7-8, but diagnosed with delayed neurological sequelae (DNS) with cognitive and motor impairments on days 22-29. Similar Methylprednisolone pulse therapy and hyperbaric oxygen therapy were given to them. The movement disorder of case 1 improved slightly during the recovery stage, while the movement disorder of case 2 worsened significantly. In case 1, the function of supplementary motor area decreased first and then increased, and the function of pallidum increased first and then decreased. Case 2 showed a reduction in the supplementary motor area and small changes in the pallidum after DNS, but both were reduced during recovery stage. The cognitive ability of case 1 remained poor, while that of case 2 improved during the recovery stage. FMRI showed damage to the right and bilateral hippocampus in case 1 and partial damage to the left hippocampus in case 2. Taken together, fMRI can be a useful method to study functional connectivity abnormalities corresponding to different prognoses.

Clinical factors for delayed neuropsychiatric sequelae from acute carbon monoxide poisoning: a retrospective study

Background

Delayed neuropsychiatric sequelae (DNS), which seriously affect the daily lives of patients, are the most common complications of carbon monoxide (CO) poisoning. No uniform screening tool is available for identifying high-risk groups. Therefore, in this study, we aimed to explore whether conventional laboratory indicators and imaging data from primary hospitals could predict the occurrence of DNS.

Methods

This retrospective observational study was conducted in a single-center primary hospital from January 1, 2021 to May 31, 2023. Participants included patients aged >18 years with acute CO poisoning. Patients with complete recovery in the acute phase were followed up by telephone and outpatient visits, and the presence of DNS was determined according to the occurrence of new neurological symptoms within 6 weeks after discharge. We obtained demographic, laboratory, and imaging data from the medical records and performed a univariate analysis. A multivariate logistic regression model was used to identify independent clinical predictors of DNS.

Results

A total of 73 patients were included in the study, of whom 25 (34.2%) developed DNS. Multivariate logistic regression analysis revealed that a longer duration of CO exposure (adjusted odds ratio (AOR): 1.262, 95% confidence interval (CI): 1.069-1.490) and the presence of acute brain lesions on diffusion-weighted imaging (DWI) (AOR: 5.117, 95% CI: 1.430-18.315) were independent risk factors for DNS. Receiver operating characteristic analyses of the duration of CO exposure were performed (area under the curve (AUC): 0.825; 95% CI: 0.731-0.918) with a cut-off value of 5.5 h, and DNS was predicted with a sensitivity of 96% and a specificity of 66.7%.

Conclusion

High cranial DWI signal within 24 h and duration of poisoning longer than 5.5 h are independent predictors of DNS. The predictive effects of conventional laboratory indicators require further standardized and large-sample studies.

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.

Correlation between Time to Hyperbaric Oxygen Therapy and Delayed Neurological Sequelae in Acute Carbon Monoxide Poisoning Patients

Carbon monoxide (CO) is one of the most common causes of intoxication. Delayed neurologic sequelae (DNS) have a major impact on prognosis of CO poisoning patients. Hyperbaric oxygen therapy (HBOT) is widely used to treat DNS. However, there is no consensus regarding the optimal timing of HBOT. This prospective study enrolled patients who visited the hospital from November 2019 to October 2022. The cutoff value for the latency to HBOT after CO exposure was determined, and the area under the receiver operating characteristic curve (AUC) was estimated. In total, 167 patients were divided into non-DNS and DNS groups. The initial Glasgow Coma Scale (GCS) score, CO exposure time, latency to HBOT after CO exposure, median length of hospital stay (p < 0.001) and creatine kinase (p = 0.016) showed significant differences. A GCS score ≤ 9 had an odds ratio (OR) of 5.059 (95% confidence interval [CI]: 1.602-15.976, p = 0.006), and latency to HBOT after CO exposure ≥ 200 min had an OR of 18.971 (95% CI: 4.310-83.508, p < 0.001). The AUC was 0.8235 (95% CI: 0.7504-0.8966). A GCS score ≤ 9 and latency to HBOT ≥ 200 min may be significant risk factors for DNS.

A charred body inside a burning car with a garden hose connected to the exhaust pipe: Post-mortem self-immolation, a complex or a complicated suicide after the ingestion of alcohol? The importance of an interdisciplinary approach

The analysis of charred bodies represents a serious challenge for forensic pathologists, and an interdisciplinary approach is often the only way to determine the cause and manner of death. We present an unusual case in which the charred body of a 61-year-old man was found inside his burning vehicle. In order to determine cause and manner of death, an interdisciplinary team was employed, with experts in forensic pathology, forensic radiology, toxicology and fire investigations. Post-mortem computed tomography, autopsy and toxicology ruled out the presence of trauma injury and detected signs of vital exposure to fire and blood alcohol levels. On the other hand, according to fire investigations, the fire started inside the car and partially burned fragments of a garden hose were found along the right side of the car. A suicide could therefore be hypothesized, with the man having attempted to poison himself with the car's exhaust fumes and having set the car on fire. The death was consistent with a complicated suicide in which the victim, in a state of reduced capability, accidentally set his car on fire and was unable to escape. The hypothesis of a complex suicide, with the car having been set deliberately on fire, could not, however, be ruled out.

Neurological Sequelae After Acute Carbon Monoxide Poisoning

Carbon monoxide poisoning (COP) is a common cause of death due to poisoning. After COP, a significant number of patients may develop a distinct type of neurological dysfunction called delayed neurological sequel (DNS). Recently, we came across a disaster of COP cases after a fire in a shared accommodation. The hostel was overcrowded and had a faulty air-conditioning/exhaust system. A total of five patients with loss of consciousness and shock were brought to us. They were diagnosed with acute COP based on their history of exposure to carbon monoxide (CO) and elevated carboxyhemoglobin levels in blood gas measurements. All patients were intubated and mechanically ventilated. Standard intensive care management was given to them, which included oxygenation, sedation, fluid resuscitation, and vasopressors. Their carboxyhemoglobin was rapidly reversed with normobaric oxygen therapy (NBO2). Three patients showed good response and neurological recovery after NBO2. Unfortunately, two patients developed DNS. DNS is a neuropsychological condition that may have cognitive, psychiatric, vestibulocochlear, motor, sensory, or diffuse demyelinating effects after COP. DNS is diagnosed in patients with a typical history of exposure to CO and a constellation of signs and symptoms. Neuroimaging, specifically magnetic resonance imaging of the brain with gadolinium contrast, is the method of choice for diagnosis. Treatment of DNS after COP begins with anticipation. All patients should receive appropriate oxygen therapy to bring down carboxyhemoglobin as soon as possible. Hyperbaric oxygen therapy (HBO2) for the treatment of COP and prevention of DNS is still debatable. In the available medical literature, there are conflicting recommendations regarding the use of HBO2 in COP/DNS. Moreover, apart from a lack of consensus, there is also a lack of clarity about optimum timing, duration, atmospheric pressure, and number of sessions of HBO2 in preventing DNS after COP. The development of DNS after COP is not directly responsible for mortality, but recovery sometimes takes a long time, which can contribute to increased morbidity and costs of treatment.

The diagnostic accuracy of carbon monoxide pulse oximetry in adults with suspected acute carbon monoxide poisoning: a systematic review and meta-analysis

Introduction

Acute carbon monoxide poisoning (COP) is one of the leading causes of intoxication among patients presenting to the emergency department (ED). COP symptoms are not always specific and may vary from mild to critical. In the last few years, COHb pulse oximeters have been developed and applied to the setting of suspected COP. The aim of this systematic review is to assess the diagnostic accuracy of CO pulse oximetry (SpCO) with carboxyhemoglobin (COHb) levels measured by blood gas analysis, used as a reference standard, in patients with suspected COP.

Methods

We developed our search strategy according to the PICOS framework, population, index/intervention, comparison, outcome, and study, considering the diagnostic accuracy of SpCO compared to COHb levels measured by blood gas analysis, used as a reference standard, in patients with suspected COP enrolled in cross-sectional studies in English. The search was performed on MEDLINE/PubMed and EMBASE in February 2022. Quality assessment was performed using the QUADAS-2 methodology. A COHb cutoff of 10% was chosen to test the sensitivity and specificity of the index test. A bivariate model was used to perform the meta-analysis. The protocol was registered on PROSPERO (CRD42022359144).

Results

A total of six studies (1734 patients) were included. The pooled sensitivity of the test was 0.65 (95% CI 0.44-0.81), and the pooled specificity was 0.93 (95% CI 0.83-0.98). The pooled LR+ was 9.4 (95% CI 4.4 to 20.1), and the pooled LR- was 0.38 (95% CI 0.24 to 0.62).

Conclusion

Our results show that SpCO cannot be used as a screening tool for COP in the ED due to its low sensitivity. Because of its high LR+, it would be interesting to evaluate, if SpCO could have a role in the prehospital setting as a tool to quickly identify COP patients and prioritize their transport to specialized hospitals on larger samples with a prospective design.

Acute Carbon Monoxide Poisoning in a Filipino Household: A Case Report

There are multiple reports already regarding acute carbon monoxide (CO) poisoning in the Philippines secondary to the misuse of portable generators, especially during times of typhoons. We present a case of unintentional carbon monoxide poisoning in a Filipino household wherein our index patient is among the five members who were unconscious before they were rushed to the hospital. Three of the household members, on the other hand, were found dead. The index patient had an increased serum fraction percentage of carboxyhemoglobin level and presented with rhabdomyolysis during admission. Neuroimaging confirmed a hypoxic-ischemic encephalopathy secondary to carbon monoxide intoxication. Even without hyperbaric oxygen therapy, the patient improved with adequate hydration, early rehabilitation, and trauma-focused psychotherapy.

A Graph Theory Study of Resting-State Functional MRI Connectivity in Children With Carbon Monoxide Poisoning

BACKGROUND

The effect of carbon monoxide (CO) poisoning on the topology of brain functional networks is unclear, especially in children whose brains are still developing.

PURPOSE

To investigate the topological alterations of the whole-brain functional connectome in children with CO poisoning and characterize its relationship with disease severity.

STUDY TYPE

Cross-sectional and prospective study.

SUBJECTS

A total of 26 patients with CO poisoning and 26 healthy controls.

FIELD STRENGTH/SEQUENCE

A 3.0 T MRI system/echo planar imaging (EPI) and 3D brain volume imaging (BRAVO) sequences.

ASSESSMENT

We used the network-based statistics (NBS) method to explore between-group differences in functional connectivity strength and a graph-theoretical-based analytic method to explore the topology of brain networks.

STATISTICAL TESTS

Student's t-test, chi-square test, NBS, Pearson correlation coefficient, and false discovery rate correction. The statistical significance threshold was set at P < 0.05.

RESULTS

The case group's brain functional network topology was impaired in comparison to the control group (reduced global efficiency and small-worldness, increased characteristic path length). According to node and edge analyses, the case group showed topologically damaged regions in the frontal lobe and basal ganglia, as well as neuronal circuits with weaker connections. Also, there was a significant correlation between the patients' coma time and the degree (r = -0.4564), efficiency (r = -0.4625), and characteristic path length (r = 0.4383) of the nodes in the left orbital inferior frontal gyrus. Carbon monoxide hemoglobin content (COHb) concentration and right rolandic operculum node characteristic path length (r = -0.3894) were significantly correlated. The node efficiency and node degree of the right middle frontal gyrus (r = 0.4447 and 0.4539) and right pallidum (r = 0.4136 and 0.4501) significantly correlated with the MMSE score.

DATA CONCLUSION

The brain network topology of CO poisoned children is damaged, which is manifested by reduced network integration and may lead to a series of clinical symptoms in patients.

EVIDENCE LEVEL

2.

TECHNICAL EFFICACY

Stage 2.

Meta-analysis of the effectiveness and safety of Xingnaojing and naloxone in the treatment of carbon monoxide poisoning

BACKGROUND

To evaluate the effectiveness and safety of Xingnaojing combined with naloxone in the treatment of carbon monoxide poisoning.

METHODS

By retrieving the literatures published in the databases of PubMed, Cochrane Library, Web of Science, Embase, Wanfang Database, Weipu Database, and China National Knowledge Infrastructure from January 2010 to September 2021, the data of randomized controlled trials (RCTs) of Xingnaojing combined with naloxone in the treatment of carbon monoxide poisoning were extracted. The methodological quality of the included RCTs was evaluated by using the tools of bias risk evaluation of Cochrane Collaboration, and the data were statistically analyzed by using RevMan 5.3 software.

RESULTS

A total of 20 literatures were included, involving in 771 cases treated by Xingnaojing combined with naloxone and 761 cases in the control group. The effective rate of the experimental group is higher than that of the control group [risk ratio (RR) = 1.20, 95% confidence interval (CI) (1.14, 1.26)]. The average awake time (STD mean difference = -2.08, 95% CI [-2.60, -1.56]), physical recovery time (STD mean difference = -2.94, 95% CI [-3.59, -2.28]), delayed encephalopathy (RR = 0.44, 95% CI [0.31, 0.62]), and adverse reactions (RR = 0.23, 95% CI [0.10, 0.54]) was lower than that of the control group.

CONCLUSION

Xingnaojing combined with naloxone in the treatment of carbon monoxide poisoning is significantly superior to naloxone, but it still needs to be further verified by high-quality large samples of RCTs.

Evaluation of a Portable Blood Gas Analyzer for Prehospital Triage in Carbon Monoxide Poisoning: Instrument Validation Study

BACKGROUND

Carbon monoxide (CO) poisoning is an important cause of morbidity and mortality worldwide. Symptoms are mostly aspecific, making it hard to identify, and its diagnosis is usually made through blood gas analysis. However, the bulkiness of gas analyzers prevents them from being used at the scene of the incident, thereby leading to the unnecessary transport and admission of many patients. While multiple-wavelength pulse oximeters have been developed to discriminate carboxyhemoglobin (COHb) from oxyhemoglobin, their reliability is debatable, particularly in the hostile prehospital environment.

OBJECTIVE

The main objective of this pilot study was to assess whether the Avoximeter 4000, a transportable blood gas analyzer, could be considered for prehospital triage.

METHODS

This was a monocentric, prospective, pilot evaluation study. Blood samples were analyzed sequentially with 2 devices: the Avoximeter 4000 (experimental), which performs direct measurements on blood samples of about 50 µL by analyzing light absorption at 5 different wavelengths; and the ABL827 FLEX (control), which measures COHb levels through an optical system composed of a 128-wavelength spectrophotometer. The blood samples belonged to 2 different cohorts: the first (clinical cohort) was obtained in an emergency department and consisted of 68 samples drawn from patients admitted for reasons other than CO poisoning. These samples were used to determine whether the Avoximeter 4000 could properly exclude the diagnosis. The second (forensic) cohort was derived from the regional forensic center, which provided 12 samples from documented CO poisoning.

RESULTS

The mean COHb level in the clinical cohort was 1.7% (SD 1.8%; median 1.2%, IQR 0.7%-1.9%) with the ABL827 FLEX versus 3.5% (SD 2.3%; median 3.1%, IQR 2.2%-4.1%) with the Avoximeter 4000. Therefore, the Avoximeter 4000 overestimated COHb levels by a mean difference of 1.8% (95% CI 1.5%-2.1%). The consistency of COHb readings by the Avoximeter 4000 was excellent, with an intraclass correlation coefficient of 0.97 (95% CI 0.93-0.99) when the same blood sample was analyzed repeatedly. Using prespecified cutoffs (5% in nonsmokers and 10% in smokers), 3 patients (4%) had high COHb levels according to the Avoximeter 4000, while their values were within the normal range according to the ABL827 FLEX. Therefore, the specificity of the Avoximeter 4000 in this cohort was 95.6% (95% CI 87%-98.6%), and the overtriage rate would have been 4.4% (95% CI 1.4%-13%). Regarding the forensic samples, 10 of 12 (83%) samples were positive with both devices, while the 2 remaining samples were negative with both devices.

CONCLUSIONS

The limited difference in COHb level measurements between the Avoximeter 4000 and the control device, which erred on the side of safety, and the relatively low overtriage rate warrant further exploration of this device as a prehospital triage tool.

Diagnostic accuracy of carboxyhemoglobin saturation with pulse CO-oximetry in patients with carbon monoxide poisoning

Objective

Carboxyhemoglobin saturation (SpCO)with pulse CO-oximetry is an alternative method in CO poisoning; however, the correlation of it with blood carboxyhemoglobin level (COHb) is still debated.The study aimed to evaluate the correlation between SpCO and venous COHb level and factors associated with the diagnostic accuracy of SpCO.

Material and methods

SpCO and venous COHb levels of patients with CO poisoning, according to a COHb level was 3%, were evaluated. The sensitivity, specificity, 95% CI (confidence interval), and the cut-off value of SpCO were calculated using ROC analysis at a 10% threshold for COHb. Agreement levels were calculated with Bland-Altman analysis. Risk factors affecting diagnostic accuracy were analyzed using logistic regression analysis.

Results

If the 10% threshold of COHb was accepted as the diagnostic threshold for CO poisoning, the sensitivity and specificity of SpCO were 98.4% and 100% (95% CI: 0.996-1.000) at the 6.85 cut-off point of SpCO. The scatter plot of COHb and SpCO showed a strong positive relationship at values of presentation and discharge (r = .979, p<0.001; r = .969, p<0.001). With a bias of 3.1% for the mean difference between-COHb and SpCO, the limits of agreement from Bland- Altman analysis were -0.7 to 7.1. For the 10% threshold, age and male gender have significantly increased false negativity rates (B = .074, p = 0.010, and B = 0.252, p = 0.011, respectively).

Conclusion

SpCO is a reliable method with high sensitivity and specificity; therefore, a lower cut-off points of SpCO compared to COHb level may be accepted to diagnose and follow-up CO poisoning.

Carbon Monoxide Poisoning Complicated by Ischemic Colitis: A Case Report and Literature Review

A 59-year-old male was found unconscious in a car filled with smoke. On arrival, he was in a semi-comatose state with hemorrhagic shock due to deep lacerations on his wrist. His carboxyhemoglobin level was 16.6%. Electrocardiography showed ST segment elevation at the precordial leads with troponin T positivity. Magnetic resonance imaging showed spotty ischemic lesions in his brain. He was treated with 100% oxygen by mechanical ventilation; however, he also developed acute respiratory distress syndrome due to an inhalation injury. His condition was complicated by bloody stools, which were judged to have been caused by ischemic colitis based on computed tomography and were managed by observation. After regaining consciousness and the improvement of the heart, lung, and bowel conditions, the patient was transported to a psychiatric hospital due to concerns regarding self-harm. Due to the small number of reported cases, the accumulation of similar cases of ischemic colitis after carbon monoxide (CO) poisoning is needed to clarify the characteristics of ischemic colitis after carbon monoxide poisoning.

Hydranencephaly following carbon monoxide poisoning during pregnancy: An uncommon and potentially fatal complication in infant

BACKGROUND

Hydranencephaly is a rare malformation of the brain system with an incidence of 0.5 per 1000 births. Its principal etiologies are bilateral occlusion of the internal carotid arteries and congenital infections.

CASE

We reported an uncommon case of hydranencephaly diagnosed in 50-day old infant and attributable to carbon monoxide (CO) poisoning during the first trimester of pregnancy.

CONCLUSIONS

We recommend a prompt diagnosis and management of CO poisoning in pregnant women since it can dramatically affect both the fetus and mother.

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.

Design Optimization of a Phototherapy Extracorporeal Membrane Oxygenator for Treating Carbon Monoxide Poisoning

We designed a photo-ECMO device to speed up the rate of carbon monoxide (CO) removal by using visible light to dissociate CO from hemoglobin (Hb). Using computational fluid dynamics, fillets of different radii (5 cm and 10 cm) were applied to the square shape of a photo-ECMO device to reduce stagnant blood flow regions and increase the treated blood volume while being constrained by full light penetration. The blood flow at different flow rates and the thermal load imposed by forty external light sources at 623 nm were modeled using the Navier-Stokes and convection-diffusion equations. The particle residence times were also analyzed to determine the time the blood remained in the device. There was a reduction in the blood flow stagnation as the fillet radii increased. The maximum temperature change for all the geometries was below 4 °C. The optimized device with a fillet radius of 5 cm and a blood priming volume of up to 208 cm3 should decrease the time needed to treat CO poisoning without exceeding the critical threshold for protein denaturation. This technology has the potential to decrease the time for CO removal when treating patients with CO poisoning and pulmonary gas exchange inhibition.

Accuracy of pulse CO-oximetry to evaluate blood carboxyhemoglobin level: a systematic review and meta-analysis of diagnostic test accuracy studies

Carbon monoxide (CO) poisoning is one of the most common causes of poisoning death and its diagnosis requires an elevated carboxyhemoglobin (COHb) level. Noninvasive CO saturation by pulse oximetry (SpCO) has been available since 2005 and has the advantage of being portable and easy to use, but its accuracy in determining blood COHb level is controversial. To evaluate the accuracy of SpCO (index test) to estimate COHb (reference test). Systematic review and meta-analysis of diagnostic test accuracy (DTA) studies. Four electronic databases were searched (Medline, Embase, Cochrane Central Register of Controlled Trials, and OpenGrey) on 2 August 2022. All studies of all designs published since the 2000s evaluating the accuracy and reliability of SpCO measurement compared to blood COHb levels in human volunteers or ill patients, including children, were included. The primary outcome was to assess the diagnostic accuracy of SpCO for estimating COHb by blood sampling by modeling receiver operating characteristic (ROC) curves and calculating sensitivity and specificity (primary measures). The secondary measures were to calculate the limits of agreement (LOA) and the mean bias. This systematic review was conducted according to the Preferred Reporting Items for a Systematic Review and Meta-analysis-DTA 2018 guidelines and has been registered on International Prospective Register of Systematic Reviews (PROSPERO, CRD42020177940). The risk of bias was evaluated using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Twenty-one studies were eligible for the systematic review; 11 could be included for the quantitative analysis of the primary measures and 18 for the secondary measures. No publication bias was found. The area under the summary ROC curve was equal to 86%. The mean sensitivity and specificity were 0.77, 95% confidence interval (CI, 0.66-0.85) and 0.83, 95% CI (0.74-0.89), respectively (2089 subjects and 3381 observations). The mean bias was 0.75% and the LOA was -7.08% to 8.57%, 95% CI (-8.89 to 10.38) (2794 subjects and 4646 observations). Noninvasive measurement of COHb (SpCO) using current pulse CO oximeters do not seem to be highly accurate to estimate blood COHb (moderate sensitivity and specificity, large LOA). They should probably not be used to confirm (rule-in) or exclude (rule-out) CO poisoning with certainty.

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.

Effectiveness of Initial Troponin I and Brain Natriuretic Peptide Levels as Biomarkers for Predicting Delayed Neuropsychiatric Sequelae in Patients with CO Poisoning: A Retrospective Multicenter Observational Study

BACKGROUND

Delayed neuropsychiatric sequelae (DNS) are a severe complication of carbon monoxide (CO) poisoning, and predicting DNS is difficult. This study aimed to investigate whether cardiac markers can be used as biomarkers to predict DNS occurrence following acute CO poisoning.

METHODS

This was a retrospective observational study that included patients with acute CO poisoning who visited two emergency medical centers in Korea from January 2008 to December 2020. The primary outcome was whether the occurrence of DNS was associated with laboratory results.

RESULTS

Of the 1327 patients with CO poisoning, 967 patients were included. Troponin I and BNP were significantly higher in the DNS group. As a result of multivariate logistic regression analysis, it was found that troponin I, mentality, creatine kinase, brain natriuretic peptide, and lactate levels independently influenced DNS occurrence in CO poisoning patients. The adjusted odds ratios for DNS occurrence were 2.12 (95% CI 1.31-3.47, p = 0.002) for troponin I and 2.80 (95% CI 1.81-3.47, p < 0.001) for BNP.

CONCLUSION

Troponin I and BNP might be useful biomarkers for predicting the occurrence of DNS in patients with acute CO poisoning. This finding can help to identify high-risk patients who require close monitoring and early intervention to prevent DNS.

Extracorporeal membrane oxygenators with light-diffusing fibers for treatment of carbon monoxide poisoning: Experiments, mathematical modeling, and performance assessment with unit cells

BACKGROUND AND OBJECTIVES: Approximately 50,000 emergency department visits per year due to carbon monoxide (CO) poisoning occur in the United States alone. Tissue hypoxia can occur at very low CO concentration exposures because CO binds with a 250-fold higher affinity than oxygen to hemoglobin. The most effective therapy is 100% hyperbaric oxygen (HBO) respiration. However, there are only a limited number of cases with ready accessibility to the specialized HBO chambers. In previous studies, we developed an extracorporeal veno-venous membrane oxygenator that facilitates exposure of blood to an external visible light source to photo-dissociate carboxyhemoglobin (COHb) and significantly increase CO removal from CO-poisoned blood (photo-extracorporeal veno-venous membrane oxygenator [p-ECMO]). One objective of this study was to describe in vitro experiments with different laser wavelength sources to compare CO elimination rates in a small unit-cell ECMO device integrated with a light-diffusing optical fiber. A second objective was to develop a mathematical model that predicts CO elimination rates in the unit-cell p-ECMO  device design upon which larger devices can be based.

STUDY DESIGN/MATERIAL AND METHODS

Two small unit-cell p-ECMO devices consisted of a plastic capillary with a length and inside diameter of 10 cm and 1.15 mm, respectively. Either five (4-1 device) or seven (6-1 device) gas exchange tubes were placed in the plastic capillary and a light-diffusing fiber was inserted into one of the gas exchange tubes. Light from lasers emitting either 635 nm or 465 nm wavelengths was coupled into the light-diffusing fiber as oxygen flowed through the gas exchange membranes. To assess the ability of the device to remove CO from blood in vitro, the percent COHb reduction in a single pass through the device was assessed with and without light. The Navier Stokes equations, Carreau-Yesuda model, Boltzman equation for light distribution, and hemoglobin kinetic rate equations, including photo-dissociation, were combined in a mathematical model to predict COHb elimination in the experiments.

RESULTS

For the unit-cell devices, the COHb removal rate increases with increased 635 nm laser power, increased blood time in the device, and greater gas exchange membrane surface-to-blood volume ratio. The 6-1 device COHb half-life versus that of the 4-1 device with 4 W at 635 nm light was 1.5 min versus 4.25 min, respectively. At 1 W laser power, 635 nm and 465 nm exhibited similar CO removal rates. The COHb half-life times of the 6-1 device were 1.25, 2.67, and 8.5 min at 635 nm (4 W), 465 nm (1 W), and 100% oxygen only, respectively. The mathematical model predicted the experimental results. An analysis of the in vivo COHb half-life of oxygen respiration therapy versus an adjunct therapy with a p-ECMO device and oxygen respiration shows a reduction from 90 min to as low as 10 min, depending on the device design.

CONCLUSION

In this study, we experimentally studied and developed a mathematical model of a small unit-cell ECMO device integrated with a light-diffusing fiber illuminated with laser light. The unit-cell device forms the basis for a larger device and, in an adjunct therapy with oxygen respiration, has the potential to remove COHb at much higher rates than oxygen therapy alone. The mathematical model can be used to optimize the design in practical implementations to quickly and efficiently remove CO from CO-poisoned blood.

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.

Optical, flow, and thermal analysis of a phototherapy extracorporeal membrane oxygenator for treating carbon monoxide poisoning

BACKGROUND

Extracorporeal membrane oxygenators (ECMO) are currently utilized to mechanically ventilate blood when lung or lung and heart function are impaired, like in cases of acute respiratory distress syndrome (ARDS). ARDS can be caused by severe cases of carbon monoxide (CO) inhalation, which is the leading cause of poison-related deaths in the United States. ECMOs can be further optimized for severe CO inhalation using visible light to photo-dissociate CO from hemoglobin (Hb). In previous studies, we combined phototherapy with an ECMO to design a photo-ECMO device, which significantly increased CO elimination and improved survival in CO-poisoned animal models using light at 460, 523, and 620 nm wavelengths. Light at 620 nm was the most effective in removing CO.

OBJECTIVE

The aim of this study is to analyze the light propagation at 460, 523, and 620 nm wavelengths and the 3D blood flow and heating distribution within the photo-ECMO device that increased CO elimination in CO-poisoned animal models.

METHODS

Light propagation, blood flow dynamics, and heat diffusion were modeled using the Monte Carlo method and the laminar Navier-Stokes and heat diffusion equations, respectively.

RESULTS

Light at 620 nm propagated through the device blood compartment (4 mm), while light at 460 and 523 nm only penetrated 48% to 50% (~2 mm). The blood flow velocity in the blood compartment varied with regions of high (5 mm/s) and low (1 mm/s) velocity, including stagnant flow. The blood temperatures at the device outlet for 460, 523, and 620 nm wavelengths were approximately 26.7°C, 27.4°C, and 20°C, respectively. However, the maximum temperatures within the blood treatment compartment rose to approximately 71°C, 77°C, and 21°C, respectively.

CONCLUSIONS

As the extent of light propagation correlates with efficiency in photodissociation, the light at 620 nm is the optimal wavelength for removing CO from Hb while maintaining blood temperatures below thermal damage. Measuring the inlet and outlet blood temperatures is not enough to avoid unintentional thermal damage by light irradiation. Computational models can help eliminate risks of excessive heating and improve device development by analyzing design modifications that improve blood flow, like suppressing stagnant flow, further increasing the rate of CO elimination.

The effect of preconditioning agents on cardiotoxicity and neurotoxicity of carbon monoxide poisoning in animal studies: a systematic review

BACKGROUND

Carbon monoxide (CO) poisoning is a common intoxication and many people die yearly due to CO poisoning and preconditioning agents attenuate brain and cardiac injury caused by intoxication. It is critical to fully understand the efficacy of new methods to directly target the toxic effect of CO, such as conditioning agents, which are currently under development. This study aims to systematically investigate current evidence from animal experiments and the effects of administration preconditions in acute and late phases after CO poisoning on cardiotoxicity and neurotoxicity.

METHODS

Four databases (PubMed, Embase, Scopus, and Web of Science) were systematically searched without language restrictions, and hand searching was conducted until November 2021. We included studies that compare preconditioning agents with the control group after CO poisoning in animals. The SYRCLE RoB tool was used for risk of bias assessments.

RESULTS

Thirty-seven studies were included in the study. Erythropoietin, granulocyte colony-stimulating factor (GCSF), hydrogen-rich saline, and N-butylphthalide (NBP) were found to have positive effects on reducing neurotoxicity and cardiotoxicity. As other preconditions have fewer studies, no valuable results can be deduced. Most of the studies were unclear for sources of bias.

DISCUSSION

Administration of the examined preconditioning agents including NBP, hydrogen-rich saline, and GCSF in acute and late phases could attenuate neurotoxicity and cardiotoxicity of CO poisoned animals. For a better understanding of mechanisms and activities, and finding new and effective preconditioning agents, further preclinical and clinical studies should be performed to analyze the effects of preconditioning agents.

Imaging of glutamate in acute carbon monoxide poisoning using chemical exchange saturation transfer

Aims

This study adopted the Glutamate Chemical Exchange Saturation Transfer (GluCEST) imaging technique to quantitatively analyze cranial glutamate and discussed the effectiveness of GluCEST values in identifying the pathogenesis of encephalopathy after CO poisoning.

Methods

The routine MRI and functional MRI scans of two cohorts of subjects (CO group, n = 29; Control group, n = 21) were performed. Between-group comparisons were conducted for GluCEST% in regions of interest (ROI), including the basal ganglia, the thalamus, the frontal lobe, the occipital lobe, the genu of corpus callosum, the cingulate gyrus, and the cuneus. Moreover, an age-stratified subgroup analysis was devised, and a correlational analysis was performed for GluCEST% in each ROI, including the time in coma, Simple Mini-Mental State Examination Scale (MMSE) score, Hamilton Anxiety Scale score, and blood COHb%.

Results

As compared to the healthy control, the CO group led to significantly increasing GluCEST% in the basal ganglia, the occipital lobe, the genu of the corpus callosum, the cingulate gyrus, and the cuneus (p < 0.05). In the subgroup analysis for age, adult patients had higher GluCEST% in the basal ganglia, the thalamus, the occipital lobe, the cingulate gyrus, and the cuneus compared to healthy adults (p < 0.05). In addition, the correlational analysis of CO-poisoned patients revealed a statistical association between the GluCEST% and the MMSE in the thalamus and the genu of the corpus callosum.

Conclusion

The GluCEST technique is superior to routine MRI in that it can identify the cerebral biochemical changes sooner after acute CO poisoning, which is significant for our understanding of the role of neurotransmitters in the pathological basis of this disease. Brain injury caused by CO poisoning may be different in adults and children.

Effects of hyperbaric oxygen on Notch signaling pathway after severe carbon monoxide poisoning in mice

Demyelination of the cerebral white matter is the most common pathological change after carbon monoxide (CO) poisoning. Notch signaling, the mechanism underlying the differentiation of astrocytes and oligodendrocytes, is critical to remyelination of the white matter after brain lesion. The purpose of this work was to determine the effects of hyperbaric oxygen (HBO) on Notch signaling pathway after CO poisoning for the explanation of the protective effects of HBO on CO-poisoning-related cerebral white matter demyelination. The male C57 BL/6 mice with severe CO poisoning were treated by HBO. And HBO therapy shortened the escape latency and improved the body mass after CO poisoning. HBO therapy also significantly suppressed protein and mRNA levels of Notch1 and Hes5 after CO poisoning. Our findings suggested that HBO could suppress the activation of Notch signaling pathway after CO poisoning, which is the mechanism underlying the neuroprotection of HBO on demyelination after severe CO poisoning.

Quantitative pupillary light reflex assessment for prognosis of carbon monoxide poisoning

Background

A non-reactive pupil in standard pupillary light reflex (sPLR) is regarded as a factor predicting neurological sequelae at 1-month after carbon monoxide (CO) poisoning. An automated pupillometer is used in the intensive care unit to quantitatively assess PLR. Quantitative PLR (qPLR) was superior to sPLR using penlight for prognosis of various neurological diseases. Therefore, this study aimed to analyze whether quantitative pupillary variables (neurological Pupil index [NPi] and qPLR) are superior to sPLR in predicting 1-month neurocognitive sequelae after acute CO poisoning.

Methods

We performed a prospective observational study of consecutive patients with acute CO poisoning admitted to an emergency department (ED) between August 2019 and December 2020 in a single academic medical center. sPLR and pupillometer examinations (qPLR and NPi) were performed by emergency physicians at the ED on hospital days 0-2. The lowest values among those recorded within 24 h and during the total measurement period were considered the 24-h and total lowest values, respectively. Global Deterioration Scale scores were measured at 1 month as an outcome and were dichotomized into favorable (1-4) or poor (5-7) outcomes.

Results

We analyzed the data of 104 adult patients with acute CO poisoning. qPLR was significantly higher in the favorable outcome group than in the poor outcome group 24-h and total lowest values (21.2% vs. 15.0%, p = 0.006 and 21.0% vs. 14.8%, p = 0.006). qPLR <18% had fair predictive power for poor neurocognitive outcomes [area under the curve (AUC), 0.70; 95% confidence interval (0.60-0.78)]. Among the patients with decreased mental status (Glasgow Coma Scale ≤12), the power of NPi and qPLR increased [AUC, 0.72 and AUC, 0.80]. NPi < 1 and qPLR <18% showed sensitivity (9.5% vs. 76.2%) and specificity (98.8% vs. 67.5%) for the prediction of poor outcomes. qPLR was significantly superior to sPLR in predicting poor neurocognitive outcomes at 1 month after CO poisoning (p = 0.007).

Conclusion

qPLR and NPi were superior to sPLR in terms of predicting poor neurocognitive outcomes. qPLR and NPi measured from hospital days 0-2 may be valuable in predicting neurocognitive outcome.

Correlation Between Rats Hippocampal ATP Content and Delayed Encephalopathy After Acute Carbon Monoxide Poisoning

OBJECTIVE

To study the correlation between the adenosine triphosphate (ATP) content in the hippocampus of rats and delayed encephalopathy after acute carbon monoxide (CO) poisoning.

METHODS

A total of 40 male Wistar rats weighing 180-230g, in accordance with the random number table, were selected and divided into the delayed encephalopathy after acute carbon monoxide poisoning (DEACMP: Rats with cognitive impairment after carbon monoxide poisoning) group (n = 32) and the control group (n = 8). A DEACMP rat model was generated by inhalation of CO. The Morris water maze evaluated the ability to learn and memorize in rats. The changes in neurons in the hippocampus of the rats were observed by hematoxylin-eosin (HE) staining. Lastly, the ATP content in the hippocampus of the rats was measured by high-performance liquid chromatography (HPLC).

RESULTS

The ATP content of the experimental group was significantly higher than that of the control group in the hippocampus of the rat model, so the difference was statistically significant (P < 0.05); the intra-group comparison was made for the ATP content in the experimental group, and the difference was statistically significant as group 21d > group 14d > group 7d (P < 0.05); and no significant difference was found between group 21d and group 28d (P > 0.05).

CONCLUSION

The changes in the ATP content in the hippocampus of the rats are correlated with the occurrence of delayed encephalopathy after acute carbon monoxide poisoning; it may take part in the pathogenesis of DEACMP. This offers some elicitation to the prevention and treatment of the disease.

Quantifying the effects of cold waves on carbon monoxide poisoning: A time-stratified case-crossover study in Jinan, China

Background

Previous studies have shown that carbon monoxide (CO) poisoning occurs mostly in winter and is associated with severe cold weather (e.g., ice storms, temperature drops). However, according to previous studies, the impact of low temperature on health has a delayed effect, and the existing research cannot fully reveal the delayed effect of cold waves on CO poisoning.

Objectives

The purpose of this study is to analyze the temporal distribution of CO poisoning in Jinan and to explore the acute effect of cold waves on CO poisoning.

Methods

We collected emergency call data for CO poisoning in Jinan from 2013 to 2020 and used a time-stratified case-crossover design combined with a conditional logistic regression model to evaluate the impact of the cold wave day and lag 0-8 days on CO poisoning. In addition, 10 definitions of a cold wave were considered to evaluate the impact of different temperature thresholds and durations.

Results

During the study period, a total of 1,387 cases of CO poisoning in Jinan used the emergency call system, and more than 85% occurred in cold months. Our findings suggest that cold waves are associated with an increased risk of CO poisoning in Jinan. When P01, P05, and P10 (P01, P05, and P10 refer to the 1st, 5th, and 10th percentiles of the lowest temperature, respectively) were used as temperature thresholds for cold waves, the most significant effects (the maximum OR value, which refers to the risk of CO poisoning on cold wave days compared to other days) were 2.53 (95% CI:1.54, 4.16), 2.06 (95% CI:1.57, 2.7), and 1.49 (95% CI:1.27, 1.74), respectively.

Conclusion

Cold waves are associated with an increased risk of CO poisoning, and the risk increases with lower temperature thresholds and longer cold wave durations. Cold wave warnings should be issued and corresponding protective policies should be formulated to reduce the potential risk of CO poisoning.

Risks of Developing Diabetes and Hyperglycemic Crisis Following Carbon Monoxide Poisoning: A Study Incorporating Epidemiologic Analysis and Animal Experiment

Purpose

Carbon monoxide (CO) poisoning may damage the pancreas, but the effects of CO poisoning on the development of diabetes and on existing diabetes remain unclear. We conducted a study incorporating data from epidemiologic analyses and animal experiments to clarify these issues.

Methods

Using the National Health Insurance Database of Taiwan, we identified CO poisoning patients diagnosed between 2002 and 2016 (CO poisoning cohort) together with references without CO poisoning who were matched by age, sex, and index date at a 1:3 ratio. We followed participants until 2017 and compared the risks of diabetes and hyperglycemic crisis between two cohorts using Cox proportional hazards regressions. In addition, a rat model was used to assess glucose and insulin levels in blood as well as pathological changes in the pancreas and hypothalamus following CO poisoning.

Results

Among participants without diabetes history, 29,141 in the CO poisoning cohort had a higher risk for developing diabetes than the 87,423 in the comparison cohort after adjusting for potential confounders (adjusted hazard ratio [AHR]=1.23; 95% confidence interval [CI]: 1.18–1.28). Among participants with diabetes history, 2302 in the CO poisoning cohort had a higher risk for developing hyperglycemic crisis than the 6906 in participants without CO poisoning (AHR = 2.12; 95% CI: 1.52–2.96). In the rat model, CO poisoning led to increased glucose and decreased insulin in blood and damages to pancreas and hypothalamus.

Conclusion

Our epidemiological study revealed that CO poisoning increased the risks of diabetes and hyperglycemic crisis, which might be attributable to damages in the pancreas and hypothalamus as shown in the animal experiments.

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.

Glutamate Chemical Exchange Saturation Transfer (GluCEST) Magnetic Resonance Imaging of Rat Brain With Acute Carbon Monoxide Poisoning

OBJECTIVES

To evaluate the diagnostic and prognostic values of glutamate chemical exchange saturation transfer (GluCEST) magnetic resonance imaging as a quantitative method for pathogenetic research and clinical application of carbon monoxide (CO) poisoning-induced encephalopathy combined with the proton magnetic resonance spectroscopy (¹H-MRS) and the related histopathological and behavioral changes.

METHODS

A total of 63 Sprague-Dawley rats were randomly divided into four groups. Group A (n = 12) was used for animal modeling verification; Group B (n = 15) was used for magnetic resonance molecular imaging, Group C (n = 15) was used for animal behavior experiments, and Group D (n = 21) was used for histopathological examination. All the above quantitative results were analyzed by statistics.

RESULTS

The peak value of carboxyhemoglobin saturation in the blood after modeling was 7.3-fold higher than before and lasted at least 2.5 h. The GluCEST values of the parietal lobe, hippocampus, and thalamus were significantly higher than the base values in CO poisoning rats (p < 0.05) and the ¹H-MRS showed significant differences in the parietal lobe and hippocampus. In the Morris water maze tests, the average latency and distance were significantly prolonged in poisoned rats (p < 0.05), and the cumulative time was shorter and negatively correlated with GluCEST.

CONCLUSION

The GluCEST imaging non-invasively reflects the changes of glutamate in the brain in vivo with higher sensitivity and spatial resolution than ¹H-MRS. Our study implies that GluCEST imaging may be used as a new imaging method for providing a pathogenetic and prognostic assessment of CO-associated encephalopathy.

Oxygenation Performance of Different Non-Invasive Devices for Treatment of Decompression Illness and Carbon Monoxide Poisoning

Study Objective: Application of high concentrations of oxygen to increase oxygen partial pressure (pO2) is the most important treatment for patients with carbon monoxide intoxication or divers with suspected decompression illness. The aim of this study was to evaluate the oxygenation performance of various non-invasive oxygen systems.

Methods: The effect of different oxygen systems on arterial pO2, pCO2 and pH and their subjective comfort was evaluated in 30 healthy participants. Eight devices were included: nasal cannula, non-rebreather mask, AirLife Open mask, Flow-Safe II CPAP device, SuperNO₂VA nasal PAP device, all operated with 15 L/min constant flow oxygen; nasal high-flow (50 L/min flow, 1.0 FiO2), non-invasive positive pressure ventilation (NPPV, 12 PEEP, 4 ASB, 1.0 FiO2) and a standard diving regulator (operated with pure oxygen).

Results: Diving regulator, SuperNO₂VA, nasal high-flow and NPPV achieved mean arterial pO2 concentrations between 538 and 556 mm Hg within 5 minutes. The AirLife Open mask, the nasal cannula and the non-rebreather mask achieved concentrations of 348–451 mm Hg and the Flow-Safe II device 270 mm Hg. Except for the AirLife open mask, pCO2 decreased and pH increased with all devices. The highest pH values were observed with NPPV, diving regulator, Flow-Safe II and nasal high-flow but apparent hyperventilation was uncommon. The AirLife Open and the non-rebreather mask were the most comfortable, the SuperNO₂VA and the nasal cannula the most uncomfortable devices.

Conclusion: A standard diving regulator and the SuperNO₂VA device were equally effective in providing highest physiologically possible pO2 as compared to nasal high-flow and NPPV.

Trends in carbon monoxide poisoning deaths in high frequency hurricane states from 2014-19: the need for prevention intervention strategies

INTRODUCTION

Hurricanes often result in power outages, which increase generator usage and carbon monoxide (CO) deaths. We aim to identify states with the highest frequency of hurricanes and evaluate the number of unintentional CO poisoning deaths by region, age, race and metropolitan distribution.

METHODS

The number of hurricanes was determined using the FEMA database, and the number of unintentional CO poisoning deaths was determined using the CDC WONDER database from 2014-19. Hurricane-associated consumer outages were obtained from the Department of Energy.

RESULTS

The number of unintentional CO poisoning deaths was as follows: Florida, South Carolina, North Carolina, Georgia and Alabama. Adults displayed a significantly higher number of unintentional CO poisoning deaths than pediatrics (P < 0.001). The total number of unintentional CO poisoning deaths was highest in the White population (P < 0.001); however, unintentional CO poisoning death rates were nearly two times higher among Black population in adults (0.5 versus 0.3) and pediatrics (0.2 versus 0.1). Medium metropolitan areas exhibited significantly more unintentional CO poisoning deaths (P < 0.001).

CONCLUSIONS

Hurricanes and unintentional CO poisoning deaths were most common in Florida. Death rates were higher among Black individuals. Medium metropolitan areas displayed significantly more unintentional CO poisoning deaths than all other areas.

Highly Selective and Low-Power Carbon Monoxide Gas Sensor Based on the Chain Reaction of Oxygen and Carbon Monoxide to WO3

Carbon monoxide (CO) poisoning can easily occur in industrial and domestic settings, causing headaches, loss of consciousness, or death from overexposure. Commercially available CO gas sensors consume high power (typically 38 mW), whereas low-power gas sensors using nanostructured materials with catalysts lack reliability and uniformity. A low-power (1.8 mW @ 392 °C), sensitive, selective, reliable, and practical CO gas sensor is presented. The sensor adopts floated WO₃ film as a sensing material to utilize the unique reaction of lattice oxide of WO₃ with CO gas. The sensor locally modulates the electron concentration in the WO₃ film, allowing O₂ and CO gases to react primarily in different sensing areas. Electrons generated by the CO gas reaction can be consumed for O₂ gas adsorption in a remote area, and this promotes the additional reaction of CO gas, boosting sensitivity and selectivity. The proposed sensor exhibits a 39.5 times higher response than the conventional resistor-type gas sensor fabricated on the same wafer. As a proof of concept, sensors with In₂O₃ film are fabricated, and the proposed sensor platform shows no advantage in detecting CO gas. Fabrication of the proposed sensor is reproducible and inexpensive due to conventional silicon-based processes, making it attractive for practical applications.

Association between Early Phase Serum Lactate Levels and Occurrence of Delayed Neuropsychiatric Sequelae in Adult Patients with Acute Carbon Monoxide Poisoning: A Systematic Review and Meta-Analysis

The primary goal of treating carbon monoxide (CO) poisoning is preventing or minimizing the development of delayed neuropsychiatric sequelae (DNS). Therefore, screening patients with a high probability for the occurrence of DNS at the earliest is essential. However, prognostic tools for predicting DNS are insufficient, and the usefulness of the lactate level as a predictor is unclear. This systematic review and meta-analysis investigated the association between early phase serum lactate levels and the occurrence of DNS in adult patients with acute CO poisoning. Observational studies that included adult patients with CO poisoning and reported initial lactate concentrations were retrieved from the Embase, MEDLINE, Google Scholar and six domestic databases (KoreaMED, KMBASE, KISS, NDSL, KISTi and RISS) in January 2022. Lactate values were collected as continuous variables and analyzed using standardized mean differences (SMD) using a random-effect model. The risk of bias was evaluated using the Quality in Prognosis Studies (QUIPS) tool, and subgroup, sensitivity and meta regression analyses were performed. Eight studies involving a total of 1350 patients were included. The early phase serum lactate concentration was significantly higher in the DNS group than in the non-DNS group in adult patients with acute CO poisoning (8 studies; SMD, 0.31; 95% CI, 0.11−0.50; I2 = 44%; p = 0.002). The heterogeneity decreased to I2 = 8% in sensitivity analysis (omitting Han2021; 7 studies; SMD, 0.38; 95% CI, 0.23−0.53; I2 = 8%; p < 0.001). The risk of bias was assessed as high in five studies. The DNS group was associated with significantly higher lactate concentration than that in the non-DNS group.

Therapeutic effect and molecular mechanism of Salvia Miltiorrhiza on rats with acute brain injury after carbon monoxide poisoning based on the strategy of internet pharmacology

The pathogenesis of brain injury caused by carbon monoxide poisoning (COP) is very complex, and there is no exact and reliable treatment in clinic. In the present study, we screened the therapeutic target and related signal pathway of Salvia Miltiorrhiza for acute COP brain injury, and clarified the pharmacological mechanism of multicomponent, multitarget, and multisignal pathway in Salvia Miltiorrhiza by network pharmacology. To further verify the therapeutic effect of Salvia Miltiorrhiza on acute brain injury based on the results of network analysis, a total of 216 male healthy Sprague Dawley rats were collected in the present study and randomly assigned to a normal control group, a COP group and a Tanshinone IIA sulfonate treatment group (72 rats in each group). The rat model of acute severe COP was established by the secondary inhalation in a hyperbaric oxygen chamber. We found that Salvia Miltiorrhiza had multiple active components, and played a role in treating acute brain injury induced by COP through multiple targets and multiple pathways, among them, MAPK/ERK1/2 signaling pathway was one of the most important. COP can start apoptosis process, activate the MAPK/ERK1/2 signaling pathway, and promote the expression of VEGF-A protein and the formation of brain edema. Tanshinone IIA can effectively inhibit apoptosis, up-regulate the expressions of VEGF-A, P-MEK1/2 and P-ERK1/2 proteins, thereby protect endothelial cells, promote angiogenesis and microcirculation, and finally alleviate brain edema.

Delayed Neuropsychiatric Sequel Following Pediatric Carbon Monoxide Poisoning: A Case Report and Literature Review

Carbon monoxide (CO) poisoning is a serious health problem. The main pathophysiological mechanism of acute CO poisoning is hypoxia due to the formation of carboxyhemoglobin (COHb). Delayed neuropsychiatric sequel (DNPS) occurs following an interval of several days to several weeks post-CO exposure and can present in many different manifestations, ranging from behavioral and mood disorders to encephalopathy and seizures and cause long-term neuropsychiatric sequel. The pathogenesis of DNPS following CO poisoning is a complex one that encompasses hypoxia-induced encephalopathy as well as inflammation, direct cellular changes and damage. The incidence varies and treatment is debated. We display a case of a previously healthy 13-year-old boy suffering from DNPS, presenting with seizures and encephalopathy and later developing optic nerve damage. Increased awareness to this condition might help diagnose future patients and aid in the understanding of the pathogenesis and treatment options for this poorly understood condition.

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).

Therapeutic Outcome of Burn Patients Treated With Hyperbaric Oxygen

Amongst various interventions for burns and inhalation injuries, hyperbaric oxygen therapy (HBOT) has recently been widely integrated as an adjunctive management of care due to its therapeutic properties in reducing tissue hypoxia, pathological inflammation, and augmenting neovascularization. However, the limitation of human clinical trials and data undermines its efficacy to be implemented as an adjunctive therapeutic modality in burns. The purpose of the literature review is to determine the efficacy of HBOT as an adjunct to standard management in burns. A review of the literature was done by searching PubMed, Cochrane, Medline, EMBASE, and Google Scholar for papers addressing the comparison of therapeutic outcomes between HBOT and non-HBOT in burns. Current research findings are conflicting, and the use of HBOT as an adjunct in burns management is still controversial. Therefore there is still a need for more data and research on the therapeutic benefits of HBOT in burn management.

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.

Bilateral Cerebral Hemorrhagic Infarctions: An Early Presentation of Carbon Monoxide Poisoning

Carbon monoxide (CO) poisoning is one of the most common causes of morbidity secondary to accidental or intentional exposure. It is a potentially life-threatening disease. We present the case of a 23-year-old male patient who slept with a gas generator the whole night in a closed room. The next morning the patient presented to emergency with altered mentation. His Glasgow Coma Scale score was 8/15 on arrival. The patient had cerebral hemorrhages on presentation with diffuse cerebral hypoxic injury and bilateral globus pallidus signals. Hemorrhagic infarction in the brain is a rare presentation of CO poisoning and even rarer as an early manifestation of this disease. We present a case of bilateral posterior cerebral hemorrhagic infarctions with a diffuse hypoxic insult as an early presentation of CO poisoning in a young male, which to our knowledge has rarely been reported. Early imaging and prompt medical attention can be life-saving.

Carbon Monoxide Poisoning With Concomitant Mucosal Injury and Chemical Pneumonitis Using Sulfuric and Formic Acids in a Self-Harm Attempt

The intentional liberation of carbon monoxide through the dehydration of formic acid has been reported with increasing frequency in the literature as a method of self-harm. Online forums have popularized this method of self-harm due to the ease of access of the required reagents, as well as the ability to perform the reaction under ambient conditions. The basis of this method of suicide is the use of sulfuric acid as a dehydrating agent, leading to the decomposition of formic acid into carbon monoxide gas. In addition to the exposure to carbon monoxide liberated by this reaction, the relatively high vapor pressure of formic acid can inadvertently lead to its inhalation and subsequently cause damage to the aerodigestive tract. We report a 21-year-old male who presented with manifestations of acute carbon monoxide poisoning and concomitant chemical pneumonitis. Increased awareness and understanding of this method of self-harm is critical in ensuring appropriate precautions are taken when caring for these individuals.

Hyperbaric phototherapy augments blood carbon monoxide removal

BACKGROUND AND OBJECTIVES

Carbon monoxide (CO) poisoning is responsible for nearly 50,000 emergency department visits and 1200 deaths per year. Compared to oxygen, CO has a 250-fold higher affinity for hemoglobin (Hb), resulting in the displacement of oxygen from Hb and impaired oxygen delivery to tissues. Optimal treatment of CO-poisoned patients involves the administration of hyperbaric 100% oxygen to remove CO from Hb and to restore oxygen delivery. However, hyperbaric chambers are not widely available and this treatment requires transporting a CO-poisoned patient to a specialized center, which can result in delayed treatment. Visible light is known to dissociate CO from carboxyhemoglobin (COHb). In a previous study, we showed that a system composed of six photo-extracorporeal membrane oxygenation (ECMO) devices efficiently removes CO from a large animal with CO poisoning. In this study, we tested the hypothesis that the application of hyperbaric oxygen to the photo-ECMO device would further increase the rate of CO elimination.

STUDY DESIGN/MATERIAL AND METHODS

We developed a hyperbaric photo-ECMO device and assessed the ability of the device to remove CO from CO-poisoned human blood. We combined four devices into a "hyperbaric photo-ECMO system" and compared its ability to remove CO to our previously described photo-ECMO system, which was composed of six devices ventilated with normobaric oxygen.

RESULTS

Under normobaric conditions, an increase in oxygen concentration from 21% to 100% significantly increased CO elimination from CO-poisoned blood after a single pass through the device. Increased oxygen pressure within the photo-ECMO device was associated with higher exiting blood PO₂ levels and increased CO elimination. The system of four hyperbaric photo-ECMO devices removed CO from 1 L of CO-poisoned blood as quickly as the original, normobaric photo-ECMO system composed of six devices.

CONCLUSION

This study demonstrates the feasibility and efficacy of using a hyperbaric photo-ECMO system to increase the rate of CO elimination from CO-poisoned blood. This technology could provide a simple portable emergency device and facilitate immediate treatment of CO-poisoned patients at or near the site of injury.

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.

Right Hemiplegia Following Acute Carbon Monoxide Poisoning

Acute carbon monoxide (CO) poisoning remains a common cause of poison-related death and influences neurological function. An 83-year-old female was transferred to our emergency unit due to hypertension with dizziness, headache, and right hemiplegia. There was no radiographic evidence of ischemic stroke. The family members reported that the patient may have been exposed to CO by briquettes burned inside a closed room. High flow oxygen therapy was given for suspected CO intoxication and her symptoms quickly improved. Although we do not have clear evidence, we presume that hemiplegia in our patient was caused by CO intoxication, based on rapid recovery with oxygen therapy, carboxyhemoglobin (COHb) level elevation (3.0%), polycythemia, and neuroimaging. Despite the hematogenous effects of CO, paralysis appeared to be more severe on her right side than on her left side. MRI and blood tests helped to support CO as the suspected cause of her hemiplegia. This case reconfirms the importance of medical interviewing by medical practitioners, even in an emergency setting.