Carbon monoxide poisoning

Carbon monoxide poisoning-induced encephalopathy in a carbon dioxide arc welder: a case report

Background

It is widely known that carbon dioxide (CO₂) arc welding generates carbon monoxide (CO). However, to the best of our knowledge, no case reports have been published regarding CO poisoning in CO₂ arc welders. Therefore, we aimed to report a case of CO poisoning-induced encephalopathy in a CO₂ arc welder in the Republic of Korea to inform about the dangers of CO exposure among CO₂arc welders.

Case presentation

A 40-year-old man working as a CO₂ arc welder for 15 years visited a local hospital with a tremor, involuntary urination, and speaking gibberish, on April 9, 2019. He stated that he had intermittent headache and forgetting symptoms for the last 5 years, and had been lost on the way to work several times. On April 9, 2019, he was diagnosed with CO poisoning-induced encephalopathy through brain magnetic resonance imaging. He received hyperbaric oxygen therapy, and some of his symptoms improved. According to the exposure assessment of his work environment, he was continuously exposed to high concentrations of CO for 15 years while operating CO₂ arc welding machines.

Conclusions

After evaluating the patient's work environment and evaluating his medical history, we concluded that his encephalopathy was caused by CO exposure during CO₂ arc welding. Thus CO₂ arc welders must be aware of the risk of CO poisoning and strive to avoid CO exposure.

Air Pollution Is Associated with Cognitive Deterioration of Alzheimer's Disease

INTRODUCTION

Dementia is one of the major causes of disability and dependency among older people worldwide. Alz-heimer's disease (AD), the most common cause of dementia among the elderly, has great impact on the health-care system of developed nations. Several risk factors are suggestive of an increased risk of AD, including APOE-ε4, male, age, diabetes mellitus, hypertension, and low social engagement. However, data on risk factors of AD progression are limited. Air pollution is revealed to be associated with increasing dementia incidence, but the relationship between air pollution and clinical AD cognitive deterioration is unclear.

METHODS

We conducted a case-control and city-to-city study to compare the progression of AD patients in different level of air-polluted cities. Clinical data of a total of 704 AD patients were retrospectively collected, 584 residences in Kaohsiung and 120 residences in Pingtung between 2002 and 2018. An annual interview was performed with each patient, and the Clinical Dementia Rating score (0 [normal] to 3 [severe stage]) was used to evaluate their cognitive deterioration. Air pollution data of Kaohsiung and Pingtung city for 2002-2018 were retrieved from Taiwan Environmental Protection Administration. Annual Pollutant Standards Index (PSI) and concentrations of particulate matter (PM10), sulfur dioxide (SO2), ozone (O3), nitrogen dioxide (NO2), and carbon monoxide (CO) were obtained.

RESULTS

The PSI was higher in Kaohsiung and compared with Pingtung patients, Kaohsiung patients were exposed to higher average annual concentrations of CO, NO2, PM10, and SO2. AD patients living in Kaohsiung suffered from faster cognitive deterioration in comparison with Pingtung patients (log-rank test: p = 0.016). When using multivariate Cox proportional hazards regression analysis, higher levels of CO, NO2, PM10, and SO2 exposure were associated with increased risk of AD cognitive deterioration. Among all these air pollutants, high SO2 exposure has the greatest impact while O3 has a neutral effect on AD cognitive deterioration.

CONCLUSIONS

Air pollution is an environment-related risk factor that can be controlled and is associated with cognitive deterioration of AD. This finding could contribute to the implementation of public intervention strategies of AD.

Pediatric Carbon Monoxide Poisoning in Southern Israel: A Cross-Sectional Study

OBJECTIVES

This study aimed to describe the epidemiology and clinical burden of unintended carbon monoxide (CO) poisoning among children in the Negev region of southern Israel.

METHODS

This was a cross-sectional retrospective study of CO poisoning patients admitted to Soroka University Medical Center in 2011 through 2015.

RESULTS

Overall, 43 cases of CO poisoning were recorded among children younger than 18 years. Five patients died, all upon admission. Poisoning due to smoke "per se" and due to CO emitted from heating devices were responsible for 28 (65.1%) and 14 (32.6%) cases, respectively. Eight (18.6%) patients suffered from convulsions, and 13 (43.3%) of 30 evaluable patients complained of headaches. Twenty-two (51.2%) were found unconscious in the field, and 7 (16.3%) were unconscious at examination at the emergency department. The average carboxyhemoglobin level on admission was 10.5% ± 10.4% (level ranging from 0.1% to 46.2%). Treatment included oxygen in 34 patients (79%) and hyperbaric oxygen therapy in 8 patients (19%). No differences were found between Bedouin and Jewish children in sex, age, residence area, source of CO poisoning, symptoms severity, and need for hyperbaric oxygen therapy. More patients with exposure to water heating devices were older than 4 years, lived in villages, and were diagnosed as having loss of consciousness in the field compared with those exposed to smoke inhalation.

CONCLUSIONS

Carbon monoxide poisoning in children is frequent in southern Israel. Education about prevention, implementation of safer standards for home heating systems, and government supervision are required management strategies to decrease the CO poisoning incidence in southern Israel.

Treatment with normobaric or hyperbaric oxygen and its effect on neuropsychometric dysfunction after carbon monoxide poisoning: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Carbon monoxide (CO) poisoning may result in acute neurological sequelae, cognitive sequelae, and delay neurological sequelae. The administration of hyperbaric oxygen (HBO) to prevent the development of delayed neurological sequelae in CO poisoning have extensively investigated but conflicting results have been reported. We performed a systematic literature review and meta-analysis of randomized controlled trials (RCTs) evaluating HBO treatment and its effect on neuropsychometric dysfunction after CO poisoning.

METHODS

We searched Medline, Embase, Pubmed, and the Cochrane Register of Controlled Trials from inception to December 2017. Eligible studies compared HBO therapy with normobaric oxygen (NBO) in patients with CO poisoning.

RESULTS

Six studies compared HBO with NBO in CO poisoning patients. Compared with patients treated with NBO, a lower percentage of patients treated with HBO reported headache (16.2% vs 16.5%, relative risk [RR] = 0.83, 95% CI = 0.38-1.80), memory impairment (18.2% vs 23.8%, RR = 0.80, 95% CI = 0.43-1.49), difficulty concentrating (15.0% vs 18.4%, RR = 0.86, 95% CI = 0.55-1.34), and disturbed sleep (14.7% vs 16.2%, RR = 0.91, 95% CI = 0.59-1.39). Two sessions of HBO treatment exhibited no advantage over one session.

CONCLUSIONS

The meta-analysis indicated that compared with CO poisoning patients treated with NBO, HBO treated patients have a lower incidence of neuropsychological sequelae, including headache, memory impairment, difficulty concentrating, disturbed sleep, and delayed neurological sequelae. Taking into consideration the cost-effectiveness of one session of HBO, one session of HBO treatment could be an economical option for patients with CO poisoning with high severity.

Accuracy of detection of carboxyhemoglobin and methemoglobin in human and bovine blood with an inexpensive, pocket-size infrared scanner

Detecting life-threatening common dyshemoglobins such as carboxyhemoglobin (COHb, resulting from carbon monoxide poisoning) or methemoglobin (MetHb, caused by exposure to nitrates) typically requires a laboratory CO-oximeter. Because of cost, these spectrophotometer-based instrument are often inaccessible in resource-poor settings. The aim of this study was to determine if an inexpensive pocket infrared spectrometer and smartphone (SCiO®Pocket Molecular Sensor, Consumer Physics Ltd., Israel) accurately detects COHb and MetHb in single drops of blood. COHb was created by adding carbon monoxide gas to syringes of heparinized blood human or cow blood. In separate syringes, MetHb was produced by addition of sodium nitrite solution. After incubation and mixing, fractional concentrations of COHb or MetHb were measured using a Radiometer ABL-90 Flex® CO-oximeter. Fifty microliters of the sample were then placed on a microscope slide, a cover slip applied and scanned with the SCiO spectrometer. The spectrograms were used to create simple linear models predicting [COHb] or [MetHb] based on spectrogram maxima, minima and isobestic wavelengths. Our model predicted clinically significant carbon monoxide poisoning (COHb ≥15%) with a sensitivity of 93% and specificity of 88% (regression r2 = 0.63, slope P<0.0001), with a mean bias of 0.11% and an RMS error of 21%. Methemoglobinemia severe enough to cause symptoms (>20% MetHb) was detected with a sensitivity of 100% and specificity of 71% (regression r2 = 0.92, slope P<0.001) mean bias 2.7% and RMS error 21%. Although not as precise as a laboratory CO-oximeter, an inexpensive pocket-sized infrared scanner/smartphone detects >15% COHb or >20% MetHb on a single drop of blood with enough accuracy to be useful as an initial clinical screening. The SCiO and similar relatively low cost spectrometers could be developed as inexpensive diagnostic tools for developing countries.

The Severity and Prognostic Markers of 148 Cases of Carbon Monoxide Poisoning by Burning Charcoal

Objective

To identify and analyse the characteristics of carbon monoxide (CO) poisoning due to burning charcoal in our locality.

Methods

This was a 3-year retrospective study. All patients presenting with CO poisoning by burning charcoal from August 1999 to December 2002 were recruited. The demographic data, initial vital signs, blood results, treatment regimens and outcomes were collected. Association between clinical outcomes and parameters were calculated.

Results

The study identified 148 patients (mean age 34.7 years) suffering from CO poisoning by burning charcoal. One hundred and forty-six cases (98.6%) were suicidal. Twenty-five patients (16.9%) were unconscious (GCS ≤ 8) on arrival. The mean initial carboxyhaemoglobin (COHb) level was 21.0%. The mortality rate was 5.4%. Fifteen cases (10.1%) required intensive care. Twelve cases (8.1%) had neurological complications and five (3.4%) suffered from delayed neurological sequelae. Initial blood results showing hyperkalemia and acidosis were associated with likelihood of unconsciousness on arrival (p = 0.007, p = 0.019 respectively). Hyperkalemia and unconsciousness on arrival were associated with longer hospital stay (p < 0.001, p < 0.001 respectively) as well as likelihood of systemic complication (p < 0.001, p < 0.001 respectively). There was no relationship between co-ingestion, age, initial COHb level, initial systolic and diastolic blood pressure with consciousness level on arrival (p = 0.188, p = 0.846, p = 0.264, p = 0.224, p = 0.755 respectively). Age, initial COHb level, acidosis, initial systolic and diastolic blood pressure did not correlate with the duration of hospital stay (p = 0.679, p = 0.176, p = 0.501, p = 0.313, p = 0.868 respectively).

Conclusion

Suicide almost accounted for all the CO poisonings by burning charcoal in our study group. It caused significant mortality and morbidity. Hyperkalemia, unconscious state and acidosis had prognostic values.

Increased Long-Term Risk of Dementia in Patients With Carbon Monoxide Poisoning: A Population-Based Study

Carbon monoxide (CO) poisoning may cause toxicity of the central nervous system and heart. However, the association between CO poisoning and long-term dementia risk remains unestablished. We investigated the incidence of dementia in patients with CO poisoning in Taiwan and evaluated whether they had a higher risk of dementia than did the general population.A nationwide population-based cohort study was conducted among patients with CO poisoning identified using Taiwan's National Health Insurance Research Database (NHIRD) during 2004 to 2013. CO poisoning was defined according to the International Classification of Diseases, Ninth Revision, Clinical Modification codes. The study cohort comprised patients with CO poisoning between 2005 and 2010 (N = 14,590). Each patient was age-, sex-, and index date-matched with 4 randomly selected controls from the comparison cohort (N = 58,360). All patients were followed from the study date until dementia development, death, or the end of 2013. Cox proportional hazards regressions were performed for comparing the hazard ratios for dementia between the 2 cohorts.Incident cases of dementia were identified from the NHIRD.After adjustment for potential confounders, the study cohort was independently associated with a higher dementia risk (adjusted hazard ratio, 2.75; 95% confidence interval, 2.26-3.35).This population-based cohort study indicated that patients with CO poisoning have a higher risk of dementia than do people without CO poisoning.

Effect of free radical scavenger, edaravone, for patients with carbon monoxide poisoning

OBJECTIVE

Chronic neurological symptoms after carbon monoxide (CO) poisoning are caused by various biological processes in the damaged brain, with free radicals playing roles as mediators in establishing pathological processes leading to chronic neurological symptoms under CO poisoning. This study aimed to clarify the effects of a free radical scavenger, edaravone, in patients with CO poisoning.

METHODS

We retrospectively compared two groups comprising patients treated with hyperbaric oxygenation alone (Group A, n=25) or edaravone in addition to hyperbaric oxygenation (Group B, n=25). Edaravone was administrated intravenously at 30 mg every 12h for 7 days. Patient characteristics, general conditions on admission, and frequency of chronic neurological symptoms were compared between groups. Among patients showing chronic neurological symptoms, cognitive function and daily activity were also compared between groups.

RESULTS

No significant differences in characteristics or general conditions on admission were identified between groups. In Group B, no patients presented with marked complications caused by edaravone. Although chronic persisting symptoms were less frequent in Group B (n=1, 0.04%) than in Group A (n=5, 20%), this difference was not significant. In the 11 patients showing chronic symptoms, scores for cognitive function and daily activity in the chronic phase were better in Group B than in Group A, but no significant differences were apparent.

CONCLUSIONS

The present results suggest that edaravone represents a tolerable and feasible treatment for CO-poisoned patients. Further studies are needed to clarify whether edaravone can favorably influence chronic neurological symptoms caused by CO poisoning.

The role of MR imaging in assessment of brain damage from carbon monoxide poisoning: a review of the literature

SUMMARY

The aim of this article is to review how MR imaging and associated imaging modalities provide clinicopathologic information on brain damage after carbon monoxide poisoning. Initially, many authors documented typical findings of conventional MR imaging in the gray matter structures such as the globus pallidus and in various regions of cerebral white matter. The focus of investigation has since shifted to observation of cerebral white matter areas that are more frequently detected on MR imaging and are more responsible for chronic symptoms than the gray matter. DWI has dramatically contributed to the ability to quantitatively assess cerebral white matter damage. Subsequently, DTI has enabled more sensitive evaluation than DWI and can demonstrate progressive pathologic changes in the early stage, allowing prediction of chronic conditions. In addition, MR spectroscopy reveals changes in metabolite levels, offering quantitative clinicopathologic information on brain damage after carbon monoxide poisoning.

Fractional anisotropy in the centrum semiovale as a quantitative indicator of cerebral white matter damage in the subacute phase in patients with carbon monoxide poisoning: correlation with the concentration of myelin basic protein in cerebrospinal fluid

Carbon monoxide (CO) poisoning leads to demyelination of cerebral white matter (CWM) fibers, causing chronic neuropsychiatric symptoms. To clarify whether fractional anisotropy (FA) from diffusion tensor imaging in the centrum semiovale can depict demyelination in the CWM during the subacute phase after CO inhalation, we examined correlations between FA in the centrum semiovale and myelin basic protein (MBP) in cerebrospinal fluid. Subjects comprised 26 adult CO-poisoned patients ≤60 years old. MBP concentration was examined for all patients at 2 weeks after CO inhalation. The mean FA of the centrum semiovale bilaterally at 2 weeks was also examined for all patients and 21 age-matched healthy volunteers as controls. After these examinations, the presence of chronic symptoms was checked at 6 weeks after CO poisoning. Seven patients displayed chronic symptoms, of whom six showed abnormal MBP concentrations. The remaining 19 patients presented no chronic symptoms and no abnormal MBP concentrations, with MBP concentrations undetectable in 16 patients. The MBP concentration differed significantly between patients with and without chronic symptoms. The mean FA was significantly lower in patients displaying chronic symptoms than in either patients without chronic symptoms or controls. After excluding the 16 patients with undetectable MBP concentrations, a significant correlation was identified between MBP concentration and FA in ten patients. The present results suggest that FA in the centrum semiovale offers a quantitative indicator of the extent of demyelination in damaged CWM during the subacute phase in CO-poisoned patients.

Assessment of damage to cerebral white matter fiber in the subacute phase after carbon monoxide poisoning using fractional anisotropy in diffusion tensor imaging

INTRODUCTION

Chronic neuropsychiatric symptoms after carbon monoxide (CO) poisoning are caused by demyelination of cerebral white matter fibers. We examined whether diffusion tensor imaging can sensitively represent damage to fibers of the centrum semiovale in the subacute phase after CO intoxication.

METHODS

Subjects comprised 13 adult patients with CO poisoning, classified into three groups according to clinical behaviors: group A, patients with transit acute symptoms only; group P, patients with persistent neurological symptoms; and group D, patients with "delayed neuropsychiatric sequelae" occurring after a lucid interval. Median fractional anisotropy (FA) and apparent diffusion coefficient (ADC) of the centrum semiovale bilaterally at 2 weeks were compared between these groups and a control group of ten healthy volunteers. Myelin basic protein (MBP) concentration in cerebrospinal fluid was examined at 2 weeks to evaluate the degree of demyelination in patients.

RESULTS

MBP concentration was abnormal or detectable for all group P and group D patients but was undetectable for all patients assigned to group A. Low FA values in groups P and D displaying chronic neurological symptoms clearly differed from those in controls and group A without chronic neurological symptoms, but ADC showed no significant differences between patient groups.

CONCLUSIONS

MBP concentration at 2 weeks after CO inhalation confirmed a certain extent of demyelination in the central nervous system of patients who would develop chronic neurological symptoms. In these patients, FA sensitively represented damage to white matter fibers in the centrum semiovale in the subacute phase after CO intoxication.

Basal ganglia lesions following carbon monoxide poisoning

PRIMARY OBJECTIVES

Carbon monoxide (CO) is the most common cause of poisoning and may result in basal ganglia lesions. This study reviewed the literature of carbon monoxide poisoning and basal ganglia lesions and prospectively assessed the prevalence of basal ganglia lesions in a cohort of patients with CO poisoning.

RESEARCH DESIGN

Literature review and prospective cohort study.

METHODS

This study conducted a comprehensive review of the literature and assessed 73 CO-poisoned patients for basal ganglia lesions on sequential MR scans. Magnetic resonance scans were obtained on day 1, 2 weeks and 6 months post-CO poisoning.

RESULTS

The literature review found basal ganglia lesions occur in 4-88% of subjects. Only one patient was found with globus pallidus lesions at 2 weeks and 6 months following CO poisoning, that were not present on the initial day 1 MR scan.

CONCLUSIONS

Basal ganglia lesions, including lesions of the globus pallidus, may be less common than previously reported.

Toxicity Associated with Carbon Monoxide

Carbon monoxide is an insidious poison that accounts for thousands of deaths each year in North America. Clinical effects maybe diverse and include headache, dizziness, nausea, vomiting,syn-cope, seizures, coma, dysrhythmias, and cardiac ischemia. Children, pregnant women, and patients who have underlying cardiovascular disease are particularly at risk for adverse out-comes. Treatment consists of oxygen therapy, supportive care, and, in selected cases, hyperbaric oxygen therapy.

Carbon monoxide poisoning

CO is an ubiquitous poison with many sources of exposure. CO poisoning produces diverse signs and symptoms that are often subtle and may be easily misdiagnosed. Failure to diagnose CO poisoning may result insignificant morbidity and mortality and permit continued exposure to a dangerous environment. Treatment of CO poisoning begins with inhalation of supplemental oxygen and aggressive supportive care. HBOT accelerates dissociation of CO from hemoglobin and may also prevent DNS. Absolute indications forHBOT for CO poisoning remain controversial, although most authors would agree that HBOT is indicated in patients who are comatose or neurologically abnormal, have a history of LOC with their exposure, or have cardiac dysfunction. Pregnancy with an elevated CO-Hgb level(>15%-20%) is also widely, considered an indication for treatment.HBOT may be considered in patients who have persistent symptoms despite NBO, metabolic acidosis, abnormalities on neuropsychometric testing, or significantly elevated levels. The ideal regimen of oxygen therapy has yet to be determined, and significant controversy exists regarding HBOTtreatment protocols. Often the local medical toxicologist, poison control center, or hyperbaric unit may assist the treating physician with decisions regarding therapy.

Carbon monoxide poisoning

CO is an insidious poison with many sources of exposure. CO poisoning produces diverse signs and symptoms, which often are subtle and can be misdiagnosed easily. Failure to diagnose CO poisoning may result insignificant morbidity and mortality and allow continued exposure to a dangerous environment. In the ED, a high index of suspicion must be maintained for occult CO exposure. Headache, particularly when associated with certain environments, and flulike illness in the wintertime with symptomatic cohabitants should raise the index of suspicion in the ED significantly for occult CO poisoning. Emergency treatment of CO poisoning begins with inhalation of supplemental oxygen and aggressive supportive care. HBOT accelerates dissociation of CO from hemoglobin and may prevent DNS. Absolute indications for HBOT for CO poisoning remain controversial, although most would agree that HBOT is indicated in patients who are comatose, are neurologically abnormal, have a history of loss of consciousness with their exposure, or have cardiac dysfunction. Pregnancy with an elevated CO-Hgb level (>15-20%) also is widely considered an indication for treatment. HBOT may be considered in patients who have persistent symptoms despite NBO, metabolic acidosis, abnormalities on neuropsychometric testing, or significantly elevated levels. The ideal regimen of oxygen therapy has yet to be determined, and significant controversy exists regarding HBOT protocols. The emergency physician may be confronted with the difficult decision regarding disposition and even transfer to a hyperbaric facility. Often the local medical toxicologist, poison control center, or hyperbaric unit can assist the emergency physician with the decision-making process.