Effect of Hyperbaric Oxygen Therapy Initiation Time in Acute Carbon Monoxide Poisoning

OBJECTIVES

Hyperbaric oxygen therapy (HBO2) is recommended for symptomatic patients within 24-hour postcarbon monoxide poisoning. Previous studies have reported significantly better outcomes with treatment administered within 6 hours after carbon monoxide poisoning. Thus, we aimed to compare the neurocognitive outcomes according to HBO2 delay intervals.

DESIGN

Retrospective analysis of data from our prospectively collected carbon monoxide poisoning registry.

SETTING

A single academic medical center in Wonju, Republic of Korea.

PATIENTS

We analyzed the data of 706 patients older than 16 years treated with HBO2 with propensity score matching. Based on carbon monoxide exposure-to-HBO2 delay intervals, we classified patients into the early (control, less than or equal to 6 hr) and late (case, 6-24 hr) groups. The late group was further divided into Case-1 (6-12 hr) and Case-2 (12-24 hr) groups. We also compared mild (nonintubated) and severe (intubated) groups.

INTERVENTIONS

HBO2.

MEASUREMENTS AND MAIN RESULTS

After propensity score matching, Global Deterioration Scale scores at 6 months postcarbon monoxide exposure showed significantly fewer poor outcome patients in the early than in the late group (p = 0.027). The early group had significantly fewer patients with poor outcomes than the Case-2 group (p = 0.035) at 1 month and than the Case-1 (p = 0.033) and Case-2 (p = 0.004) groups at 6 months. There were significantly more patients with poor prognoses at 6 months as treatment interval increased (p = 0.008). In the mild cohort, the early group had significantly fewer patients with poor 6-month outcomes than the late group (p = 0.033).

CONCLUSIONS

Patients who received HBO2 within 6 hours of carbon monoxide exposure had a better 6-month neurocognitive prognosis than those treated within 6-24 hours. An increase in the interval to treatment led to an increase in poor outcomes.

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.

Carbon monoxide increases utero-placental angiogenesis without impacting pregnancy specific adaptations in mice

BACKGROUND

Cigarette smokers have a reduced risk of developing preeclampsia, possibly attributed to an increase in carbon monoxide (CO) levels. Carbon monoxide is a gasotransmitter that has been implicated in maintaining vascular tone, increasing angiogenesis, and reducing inflammation and apoptosis at physiological concentrations. Moderately increasing CO concentrations may have therapeutic potential to prevent or treat preeclampsia; however, the effects of CO on pregnancy are under studied. Our objective was to investigate the effect of CO on major angiogenic and inflammatory markers in pregnancy, and to evaluate the effect of CO on indicators of placental health.

FINDINGS

Pregnant CD-1 mice were constantly exposed to either ambient air or 250 ppm CO from conception until gestation day (GD)10.5 or GD16.5. Using a qRT-PCR array, we identified that CO increased expression of major angiogenic genes at the implantation site on GD10.5, but not GD16.5. Pro-inflammatory cytokines in the plasma and tissue lysates from implantation sites in treated mice were not significantly different compared to controls. Additionally, CO did not alter the implantation site phenotype, in terms of proliferative capacity, invasiveness of trophoblasts, or abundance of uterine natural killer cells.

CONCLUSIONS

This study suggests that CO exposure is pro-angiogenic at the maternal-fetal interface, and is not associated with demonstrable concerns during murine pregnancy. Future studies are required to validate safety and efficacy of CO as a potential therapeutic for vascular insufficiency diseases such as preeclampsia and intrauterine growth restriction.

A case report on the acute and late complications associated with carbon monoxide poisoning: Acute kidney injury, rhabdomyolysis, and delayed leukoencephalopathy

RATIONALE

Acute kidney injury (AKI), rhabdomyolysis, and delayed leukoencephalopathy after carbon monoxide (CO) poisoning are very rare. We report a case presenting with AKI, rhabdomyolysis, and delayed leukoencephalopathy after CO poisoning.

PATIENT CONCERNS

The patient was admitted to our emergency department due to loss of consciousness after CO exposure during a suicide attempt.

DIAGNOSES

Laboratory findings revealed elevated carboxyhemoglobin, serum creatinine, and serum muscle enzyme levels. Initially, this patient was diagnosed with AKI and rhabdomyolysis due to CO poisoning. A month after the CO poisoning, she showed neuropsychiatric symptoms. Brain magnetic resonance imaging showed white-matter hyperintensity on the T2 flair image. Therefore, she was diagnosed with delayed leukoencephalopathy after CO poisoning.

INTERVENTIONS

At the same time as diagnosis of AKI and rhabdomyolysis, the normobaric oxygen and hydration therapies were performed. A month later, rehabilitation was started due to delayed leukoencephalopathy.

OUTCOMES

Her renal function and muscle enzyme levels were completely restored with alert mental status. She could walk with the aid of a walker at last visit.

LESSONS

This case shows that we should consider about rare acute and late complications such as AKI, rhabdomyolysis, and delayed leukoencephalopathy after CO poisoning.

Hyperbaric oxygen therapy decreases QTc dispersion that increased in CO poisoning

Myocardial injury is a frequent consequence of moderate to severe CO (carbon monoxide) poisoning and a significant predictor of mortality in CO injury. Electrocardiography (ECG) is an easily accessible diagnostic tool for evaluating myocardial damage. Increased QT interval and QT dispersion are related to heterogeneity of regional ventricular repolarization and can develop into arrhythmias. It has been reported that QT interval and QT dispersion increase in patients with CO poisoning. Hyperbaric oxygen (HBO2) therapy has been used successfully in treating patients with CO poisoning. The aim of this study was to investigate change of corrected QT (QTc) interval and QTc dispersion after HBO2 therapy. This study included 31 patients with CO poisoning. QTc dispersion increased in patients with CO poisoning. The mean QTc dispersion was 54.94 milliseconds (ms) on admission. The mean QTc dispersion decreased to 35.74 ms after HBO2 therapy (P=0.003). There was also a correlation between carboxyhemoglobin level and QTc dispersion (P=0.029). HBO2 therapy, which decreases QTc dispersion, may improve the myocardial electrical homogeneity and reduce the risk of ventricular arrhythmia and cardiac death. Physicians should be aware of the effect of HBO2 therapy on myocardial damage when treating patients with CO poisoning. The ECGs should be examined carefully before referring or excluding HBO2 therapy.

Emergency department management of smoke inhalation injury in adults

Smoke inhalation injury portends increased morbidity and mortality in fire-exposed patients. Upper airway thermal burns, inflammation from lower airway irritants, and systemic effects of carbon monoxide and cyanide can contribute to injury. A standardized diagnostic protocol for inhalation injury is lacking, and management remains mostly supportive. Clinicians should maintain a high index of suspicion for concomitant traumatic injuries. Diagnosis is mostly clinical, aided by bronchoscopy and other supplementary tests. Treatment includes airway and respiratory support, lung protective ventilation, 100% oxygen or hyperbaric oxygen therapy for carbon monoxide poisoning, and hydroxocobalamin for cyanide toxicity. Due to its progressive nature, many patients with smoke inhalation injury warrant close monitoring for development of airway compromise.

Clinical chameleons: an emergency medicine focused review of carbon monoxide poisoning

Carbon monoxide (CO) is a colorless, odorless gas that is found in the environment, in the home, and in the human body as a normal part of mammalian metabolism. Poisoning from CO, a common exposure, is associated with significant morbidity and mortality if not recognized and treated in a timely manner. This review evaluates the signs and symptoms of CO poisoning, conditions that present similar to CO poisoning, and an approach to the recognition and management for CO poisoning. CO poisoning accounts for thousands of emergency department visits annually. If not promptly recognized and treated, it leads to significant morbidity and mortality. CO poisoning poses a challenge to the emergency physician because it classically presents with non-specific symptoms such as headache, dizziness, nausea, and vomiting. Due to nonspecific presentations, it is easily mistaken for other, more benign diagnoses such as viral infection. The use of specific historical clues such as exposure to non-conventional heat sources or suicide attempts in garages, as well as the use of targeted diagnostic testing with CO-oximetry, can confirm the diagnosis of CO poisoning. Once diagnosed, treatment options range from observation to the use of hyperbaric oxygen. CO poisoning is an elusive diagnosis. This review evaluates the signs and symptoms CO poisoning, common chameleons or mimics, and an approach to management of CO poisoning.

Quantitative Romberg's test in acute carbon monoxide poisoning treated by hyperbaric oxygen

OBJECTIVE

The aim of this study was to evaluate whether monitoring of acute carbon monoxide-poisoned (COP) patients by means of quantitative Romberg's test (QR-test) during a hyperbaric oxygen (HBO₂) therapy regimen could be a useful supplement in the evaluation of neurological status.

METHODS

We conducted a retrospective study (2000-2014) in which we evaluated data containing quantitative sway measurements of acute COP patients (n = 58) treated in an HBO₂ regimen. Each patient was tested using QR-test before and after each HBO₂ treatment. Data were analyzed using linear mixed models (LMM). In each LMM, sway prior to HBO₂ therapy was set as the fixed effect and change in sway after HBO₂ therapy was set as the response variable. Patient, treatment number, weight and age were set as random effects for all LMMs.

RESULTS

From the LMMs we found that larger values of sway prior to HBO₂ produced a negative change in sway. We found no correlation between CO level and sway (P=0.1028; P=0.8764; P=0.4749; P=0.5883). Results showed that loss of visual input caused a significant increase in mean sway (P=0.028) and sway velocity (P⟨0.0001).

CONCLUSIONS

The Quantitative Romberg's test is a fast, useful supplement to neurological evaluation and a potential valuable tool for monitoring postural stability during the course of treatment in acute COP patients.

MRI and clinical manifestations of delayed encephalopathy after carbon monoxide poisoning

To explore the relationship between the clinical manifestations and functional magnetic resonance images of delayed encephalopathy after carbon monoxide intoxication. Six patients received the MRI were diagnosed with delayed encephalopathy after carbon monoxide (CO) poisoning. Clinical manifestations were observed in each patient. MRI revealed multiple lesions. The majority of the lesions were located in the globus pallidus, sub cortical white matter, and basal ganglia. The cognitive injury, akinetic mutism, fecal and uroclepsia, forced crying, forced laughing and extra pyramidal syndromes such as chorea and parkinsonism were manifested in clinic. Cognitive impairment improved greatly while involuntary movements only improved slightly after several months. Meanwhile brain MRI suggested remarkable improvement. Neuroimaging directly correlated with the clinical manifestations.

Carbon Monoxide Poisoning In Children: Diagnosis And Management In The Emergency Department

Approximately 5000 children present to the emergency department annually with unintentional carbon monoxide poisoning. Children may be more vulnerable to carbon monoxide poisoning because of their increased metabolic demand and their inability to vocalize symptoms or recognize a dangerous exposure, and newborn infants are more vulnerable to carbon monoxide poisoning because of the persistence of fetal hemoglobin. Mild carbon monoxide poisoning may present as viral symptoms in the absence of fever. While headache, nausea, and vomiting are the most common presenting symptoms in children, the most common symptom in infants is consciousness disturbance. This review discusses the limitations of routine pulse oximetry and carboxyhemoglobin measurement in determining carbon monoxide exposure, and notes effects of co-ingestions and comorbidities. Although the mainstay of treatment is 100% oxygen, the current evidence and controversies in the use of hyperbaric oxygen therapy in pediatric patients is reviewed, along with its possible benefit in preventing delayed neurologic sequelae.

The Evaluation of Myocardial Damage in 83 Young Adults with Carbon Monoxide Poisoning in the East Anatolia Region in Turkey

Carbon monoxide (CO) poisoning is the leading cause of death from intoxication. In CO poisoning, it is important to know if there are any symptoms regarding myocardial damage, which are usually unobserved as a result of hypoxia. This study was planned to assess myocardial damage in young healthy patients with CO poisoning. Eighty-three young healthy cases who had been exposed to CO were included in this study. The demographic and clinical characteristics, the origin of CO gas and smoking habits of the patients were recorded. The evaluation of ECG, peripheral ABG, complete blood count and serial cardiac biomarkers (creatine kinase, creatine kinasemyocardial band and troponin I) measurements were performed in all cases. Additionally, echocardiogram (ECHO) and myocardial perfusion single-photon emission computed tomography (SPECT) were performed at the appropriate times in all cases. The mean age of the patients was 27.39 /10.9 years. The main complaint of the patients was loss of consciousness with a 62.7% rate. The average carboxyhaemoglobin level of the patients was 34.49 /15.9%. Sinus tachycardia was present in 26.5% of patients. Diagnostic ischaemic ECG changes were present in 14.4% of patients. In myocardial SPECT, myocardial ischaemic damage was observed in 9 cases, in 6 of whom ECHO findings were also confirmed. Myocar-dial damage due to CO poisoning should not be ignored. If patients are at risk in terms of myocardial damage, further studies, such as ECHO and scintigraphy are needed to determine myocardial damage resulting from CO poisoning. However, in the young adults of the risk group, if the baseline ECG and serial cardiac biomarkers are normal, further studies such as ECHO and scintigraphy, considering the length of exposure and the severity of poisoning, may not be necessary for the evaluation of myocardial damage due to CO poisoning.

A cost effective parameter for predicting the troponin elevation in patients with carbon monoxide poisoning: red cell distribution width

OBJECTIVE

Carbon monoxide (CO) poisoning is very common worldwide. Despite the fact that CO is known to have cardiotoxic effects, as it has non-specific symptoms; cardiotoxicity could easily be overlooked, especially when troponin is not measured. The present study aimed to evaluate the association between troponin I levels and red cell distribution width (RDW) levels, which can be measured rapidly, easily, and affordably in the Emergency Room (ER).

PATIENTS AND METHODS

This single-center observational study included a total of 504 consecutive patients, who presented to the ER due to CO poisoning between January 2011 and June 2015. The diagnosis of CO poisoning was made according to the medical history and carboxyhemoglobin (COHb) level of >5%. Elevated troponin test levels, which measure >0.04 ng/ml for our laboratory, were accepted as positive.

RESULTS

Patients (mean age 37±14) were classified into two groups: those who had positive troponin levels (38%) and those that did not. Patients with positive troponin, who were older, had longer CO exposure time and higher creatinine, COHb and RDW levels at the index admission following CO poisoning than patients with negative troponin. In a multivariate logistic regression model with forward stepwise method, age, COHb level, CO exposure time, and RDW (HR=1.681, 95% CI: 1.472-1.934, p<0.001) remained associated with an increased risk of troponin positivity following adjustment for the variables that were statistically significant in the univariate analysis and correlated with RDW.

CONCLUSIONS

In patients presenting to the ER with CO poisoning, RDW can be helpful for the risk stratification of troponin positivity.

[A significance of measurement of breathing nervous regulation, respiratory resistance and spirometry in clinical toxicology - retrospective review]

The exogenous central nervous system depressants such opioides, alcohol and carbon monoxide may affect nervous respiratory regulation and lead to disturbances in respiratory system efficiency. The aim of this study was to evaluate the breathing nervous regulation and ventilatory efficiency in patients treated in Clinical Toxicology, UJCM in Krakow in the period 1994- 2000.

METHODS

There were 385 persons under examination: 144 alcohol abusers and 70 opiate abusers (group I), 91 persons treated because of acute carbon monoxide poisoning (group II) and 80 healthy persons - control group. The examinations performed before and after treatment included measurements of respiratory pattern parameters, occlusion pressure and evaluation of ventilatory efficiency determined on the basis of “flow-volume” loop results, spirometry and the measurements of respiratory tract resistance.

RESULTS

The central respiratory drive (VT/T(in) index) and the parasympathetic control of breathing cycle (T(in)/ T(tot) index) were similar in alcohol and opiate abusers in the initial examination but in abusers classified to methadone maintenance treatment programme the VT/T(in) index was elevated. After treatment the values of both indices were similar. In the group of acute CO poisoned patients the disturbances in breathing regulation were connected with increased value of the VT/Tin parameter and the diminished of T(in)/T(tot) value. After treatment in the slightly CO poisoned patients the both respiratory pattern components were comparable to the healthy control group but in the moderately and severely poisoned group the VT/T(in) index was elevated and the T(in)/T(tot) index was lessened compared to the controls. The values of respiratory resistance were higher than upper level of normal values (except participants of methadone programme). The bronchial obturation was most often stated disturbance in respiratory system efficiency, especially in alcohol abusers. Ventilatory parameters in moderate and severe CO poisoned were significantly lower than in the slightly poisoned patients.

CONCLUSION

Presented methods of evaluation of respiratory system efficiency and nervous breathing regulation are of special value and should be implemented in clinical toxicology as essential to diagnosis and monitoring, especially in case of alcohol and drug dependent patients and in patients poisoned with central nervous system depressants.

[Delayed neurological syndrome after CO intoxication of elderly female]

This article discusses the case history of an 87-year old woman with loss of consciousness following accidental CO intoxication. A few weeks later, the patient's cognitive abilities progressively deteriorated. This is hence a case of Delayed Neurological Symptoms after CO intoxication. This condition occurs in 40% of patients with CO intoxication and manifests itself 3-240 days after apparent recovery. Symptoms can linger for a long time and are in some cases even permanent. Treatment of CO intoxication usually consists of administering normobaric oxygen and in certain cases hyperbaric oxygen. The role of treatment with hyberbaric oxygen in delayed neurological symptoms after CO intoxication remains controversial, however.

Lack of pupil reflex and loss of consciousness predict 30-day neurological sequelae in patients with carbon monoxide poisoning

Background

Predicting the neurological sequelae of carbon monoxide poisoning (COP) has not been well studied. We investigated the independent predictors of neurological sequelae in patients with COP and combined these predictors to predict the prognosis.

Methods

This study was conducted at four hospitals in Shandong Province, China. Data were retrospectively collected from 258 patients with COP between November 1990 and October 2011. Thirty-day neurological sequelae were the primary endpoints.

Results

A lack of pupil reflex and a loss of consciousness appear to be independent predictors for neurological sequelae in patients with COP. The presence of either one had a sensitivity of 77.0% (95% confidence interval [CI]: 69.3–83.2), a specificity of 47.1% (95% CI: 38.3–56.0), positive predictive value (PPV) of 62.9% (95% CI: 55.2–70.1), and a negative predictive value (NPV) of 63.6% (95% CI: 52.6–73.4). With both predictors present, the sensitivity was 11.5% (95% CI: 6.9 to 18.3), the specificity was 99.2 (95% CI: 94.7–100.0), the PPV was 94.1% (95% CI: 69.2–99.7), and the NPV was 49.0% (95% CI: 42.5–55.5).

Conclusions

The risk for neurological sequelae apparently increased with the number of independent predictors. In patients with both predictors, the risk for neurological sequelae was 94.1%. Almost all (99.2%) patients with neither predictor had no neurological sequelae. This finding may help physicians make decisions about and dispositions for patients with COP. For patients with a higher risk, earlier treatment and more appropriate utilization of health care services, including hyperbaric oxygen, should be considered.

Longitudinal changes in the dopamine transporter and cognition in suicide attempters with charcoal burning

Suicide with charcoal burning, which results in carbon monoxide (CO) poisoning, is common in Asia. This study was designed to elucidate associations between changes in the dopamine transporter (DAT) and cognitive function in patients following CO poisoning during a follow-up period of 6 months. Participants comprised 31 healthy controls (HCs) and 21 CO poisoning patients. Each subject underwent single photon emission computed tomography with [(99m)Tc] TRODAT-1 to measure DAT availability and completed a cognitive battery assessing attention, memory, and executive function. For CO poisoning patients, a second DAT measurement and repeated cognitive evaluations were performed 6 months later. At baseline, DAT availability over bilateral striatum in CO poisoning subjects was significantly lower than in HCs. After 6 months, there was no significant change of DAT availability in CO poisoning patients. CO poisoning patients also had worse cognitive performance in all domains compared with HCs at baseline. After 6 months, most cognitive functions were significantly improved, except for the Wisconsin Card Sorting Test (WCST), a measure of executive function. Interestingly, changes in the WCST were significantly correlated with changes in DAT availability during the 6-month follow-up period. The persistence of reduced DAT availability and its association with impaired performance on the WCST indicate a crucial role of DAT in the recovery of executive function following CO poisoning.

The effect of fatal carbon monoxide poisoning on the equilibria between cell membranes and the electrolyte solution

The effect of fatal carbon monoxide poisoning on equilibria between cell membranes and surrounding ions was described using a theoretical four-equilibria model. The model was developed to obtain parameters characterizing the interactions between solution ions and erythrocyte or thrombocyte membrane surface. The parameters are the total surface concentrations of both acidic and basic groups C A, C B and their association constants with solution ions K AH, K BOH. These parameters were used to calculate the theoretical values of surface charge density. The model was validated by comparison of these values to experimental data, which were determined from the electrophoretic mobility measurements of the blood cells. The experimental and theoretical surface charge density values agree at pH 2-8, and at higher pH, the deviation was observed.

[Dynamics of morphologic changes in tracheobronchial system in patients with acute carbon monoxide poisoning complicated by thermochemical damage to respiratory tract]

The authors identified three severity degrees of thermochemical damage to respiratory tract during acute carbon monoxide poisoning. Follow-up bronchoscopic studies were performed, and characteristic signs of thermochemical damage to respiratory tract in acute carbon monoxide poisoning were diagnosed. Evidence is that the signs were following certain sequence: from edema and hyperemia of respiratory tract lining to severe purulent discharge.

[Hyperbaric oxygen treatment of poisoning]

Experiments have suggested reduction of neurological sequelae from carbon monoxide (CO) poisoning by treatment with hyper-baric oxygen (HBO). Randomised clinical trials have, however, been ambiguous. The discrepancy may be explained by timing of HBO relative to exposure. For other asphyxiants data are too sparse for a qualified judgement. Until more evidence is available, we suggest that HBO is used exclusively for moderate and severe CO poisoning within a time window of 12 hours.

Delayed leukoencephalopathy after acute carbon monoxide intoxication

Delayed leukoencephalopathy is an uncommon complication of hypoxic-ischemic events of different etiologies, including carbon monoxide intoxication. We present a case of a 40-year-old male patient who was admitted with rapidly progressive neurocognitive and behavioral deficits. There was a history of accidental carbon monoxide intoxication one month before, presenting with loss of consciousness and short hospitalization, followed by a complete clinical recovery. The imaging studies in the delayed phase depicted confluent, symmetric supra-tentorial white matter lesions in keeping with diffuse demyelinization. Restricted diffusion and metabolite abnormalities in magnetic resonance proton spectroscopy were also seen. The diagnosis of CO-mediated delayed post-hypoxic leukoencephalopathy was assumed after exclusion of other mimickers. Hyperbaric oxygen therapy was tentatively performed and the patient had a favorable clinical and radiological evolution.

Are Iranians aware of carbon monoxide poisoning: symptoms and its prevention strategies?

Carbon monoxide (CO) poisoning is still a health problem all over the world. Informing users about symptoms and suggesting annual inspection of CO producing devices will result in CO poisoning reduction. The goal of this study was to evaluate awareness about CO poisoning symptoms and its prevention ways in Iranian population. In this study, a total of 700 patients' family members attended Imam Khomeni hospital were asked to enroll in the study. A structured questionnaire was used including demographic characteristics, devices which were used at home, awareness of CO poisoning symptoms, awareness of CO detectors, the last time that tubal patency of devices are checked, if it is helpful to open the window to fix gas leak and if surveying devices by an expert at the beginning of the cold season is recommended. A total of 635 participants completed questionnaires. The most used device was gas water heater followed by gas heater. Five hundred and nine reported that they are aware of CO poisoning symptoms (80.1%), 398 (62.6%) stated that it is possible to detect CO leak and 566 (89.1%) told CO detectors would be helpful for reduction of mortality from CO poisoning. Fifty percent of participants had not checked their devices since they have bought their devices. Five hundred and thirty-six (84.4%) reported that opening window could help CO leak, and 596 (93.8%) agreed that an expert checked their fuel-burning devices at the beginning of the winter. Iranian people are not aware of all CO poisoning symptoms. Developing a national strategy for CO surveillance and people education will be helpful.

Potential use of hyperoxygenated solution as a treatment strategy for carbon monoxide poisoning

Aim

Carbon monoxide (CO) poisoning can cause permanent damage in tissues that are sensitive to hypoxia. We explored the feasibility and efficacy of using a hyperoxygenated solution (HOS) to treat severe acute CO poisoning in an animal model.

Methods

Male Sprague-Dawley rats were subjected to CO poisoning. The HOS was administered into the femoral vein of these rats through a catheter (10 ml/kg). Carboxyhemoglobin (COHb) and blood gases were used to assess the early damage caused by CO poisoning. S100β was measured to predict the development of late cognitive sequelae of CO. The Morris water maze test was performed to assess cognitive function, and Nissl staining was performed to observe histologic change.

Results

The COHb concentrations rapidly decreased at 5 min after the HOS administration; however, the PaO₂ and SaO₂ in rats treated with HOS increased significantly 5 min after the HOS administration. The S100β concentrations, which increased significantly after CO poisoning, increased at a much slower rate in the rats treated with HOS (HOS group) compared with the rats treated with O₂ inhalation (O₂ group). The escape latency in the place navigation test was shortened after CO poisoning on days 11-15 and days 26-30, and the swimming time in quadrant 4 in the spatial probe test on days 15 and 30 after CO poisoning was prolonged in the rats treated with HOS injection compared with the rats treated with oxygen inhalation or normal saline injection. The neuronal degeneration in the HOS group was alleviated than that in the CO or O₂ group.

Conclusion

HOS efficiently alleviates the brain damage in acute CO-poisoned rats and thus may serve as a new way to treat human patients with CO poisoning in clinical practice.

Carbon monoxide induces cardiac arrhythmia via induction of the late Na+ current

RATIONALE

Clinical reports describe life-threatening cardiac arrhythmias after environmental exposure to carbon monoxide (CO) or accidental CO poisoning. Numerous case studies describe disruption of repolarization and prolongation of the QT interval, yet the mechanisms underlying CO-induced arrhythmias are unknown.

OBJECTIVES

To understand the cellular basis of CO-induced arrhythmias and to identify an effective therapeutic approach.

METHODS

Patch-clamp electrophysiology and confocal Ca(2+) and nitric oxide (NO) imaging in isolated ventricular myocytes was performed together with protein S-nitrosylation to investigate the effects of CO at the cellular and molecular levels, whereas telemetry was used to investigate effects of CO on electrocardiogram recordings in vivo.

MEASUREMENTS AND MAIN RESULTS

CO increased the sustained (late) component of the inward Na(+) current, resulting in prolongation of the action potential and the associated intracellular Ca(2+) transient. In more than 50% of myocytes these changes progressed to early after-depolarization-like arrhythmias. CO elevated NO levels in myocytes and caused S-nitrosylation of the Na(+) channel, Na(v)1.5. All proarrhythmic effects of CO were abolished by the NO synthase inhibitor l-NAME, and reversed by ranolazine, an inhibitor of the late Na(+) current. Ranolazine also corrected QT variability and arrhythmias induced by CO in vivo, as monitored by telemetry.

CONCLUSIONS

Our data indicate that the proarrhythmic effects of CO arise from activation of NO synthase, leading to NO-mediated nitrosylation of Na(V)1.5 and to induction of the late Na(+) current. We also show that the antianginal drug ranolazine can abolish CO-induced early after-depolarizations, highlighting a novel approach to the treatment of CO-induced arrhythmias.

QT dispersion in carbon monoxide poisoning

BACKGROUND

Carbon monoxide (CO) poisoning are serious health problems, and effect of reducing the blood's oxygen carrying capacity. Deaths due to CO poisoning are mostly related to myocardial injury and central nervous system pathologies.

AIM

The objective of this study was to determine the relationship between carbon monoxide intoxication, QT dispersion, and cardiac markers.

MATERIALS AND METHODS

Patients with possible CO intoxication symptoms were evaluated to be eligible for the study. Patients' demographic data, carboxyhemoglobin levels, cardiac markers and QT interval measurements were recorded to the study form.

RESULTS

A total of 127 patients (79 CO intoxicated and 48 controls) were included into the study with a mean age of 38.6 +/- 14.1 years and 62.2% of them were female. Average levels of patient's carboxyhemoglobin were 21.3 +/- 9. QT dispersion (39.0 +/- 10.8 vs 24.4 +/- 6.2; p < 0.001) and corrected QT dispersion (46.2 +/- 14.7 vs. 25.3 +/- 6.2; p < 0.001) were longer than the control group. Both QT dispersion (39.0 +/- 10.8 vs. 23.6 +/- 7.0; p < 0.001) or corrected QT dispersion (46.2 +/- 14.7 vs. 27.1 +/- 8.7; p < 0.001) were also decreased after one week later from the admission.

CONCLUSION

Carbon monoxide intoxication is related to increased QT dispersion. Emergency physicians should measure QT dispersion in CO intoxicated patients in order to predict the electrical instability in myocardium and future adverse events.

Diagnosis and management of carbon monoxide poisoning in the emergency department

An 89-year-old female is found by her family, lying unconscious on her kitchen floor after they had been unable to reach her by phone for several hours. EMS is activated and when the paramedics arrive, they note that the gas oven is on, and there is thin, gray smoke coming from around the door. The house gas supply is turned off, windows are opened, and the family and the patient are immediately evacuated from the home. En route to the hospital, the patient is placed on high-flow oxygen at 15 liters per minute by non-rebreather mask. Her bedside glucose determination is 229 mg/dL. Vital signs are within normal limits during transport. She opens her eyes to sternal rub, and makes spontaneous movements of all extremities. Upon arrival to the ED, the patient becomes more alert and is able to respond to your questions. She tells you that she remembers putting a tray of calzones into the oven, after which she has no recall of the day's events. She has a past medical history of "well-controlled" hypertension, hyperlipidemia, and non-insulin-dependent diabetes. Her medications include hydrochlorothiazide 25 mg daily, lisinopril 10 mg daily, simvastatin 20 mg daily, and metformin 1000 mg twice daily. On physical examination, weight is 65 kg, blood pressure is 97/50 mm Hg, heart rate is 113 beats per minute, respiratory rate is 22 breaths per minute, temperature is 37.1 degrees C (98.8 degrees F), and oxygen saturation is 99% on 15 liters per minute via non-rebreather mask. She appears her stated age. Cardiopulmonary examination is remarkable only for tachycardia. Her abdomen is soft and non-tender with normal bowel sounds. Her skin is warm and dry, and there is no peripheral edema. Her cranial nerves are intact, with briskly reactive, symmetric pupils. Motor and sensory examination is non-focal, and cerebellar testing is notable only for an intention tremor on finger-nose-finger test. Gait is normal and speech is fluent and without errors. Laboratory testing shows a hemoglobin of 10.3 g/dL and a leukocyte count of 11.7 x 10(9)/L. Electrolyte results fall within the normal range, and her serum creatinine is 1.7 mg/dL. Qualitative CK-MB and troponin I tests are positive, and the sample has been sent to the STAT lab for quantitative testing. Serum carboxyhemoglobin level is 15% with normal serum pH on an arterial blood gas. An ECG reveals deep, down-sloping inferior and lateral ST-segment depressions which were not present on a routine cardiogram 1 month prior. You have many questions about this patient's care. What symptoms and physical signs need to be addressed and treated? What additional diagnostic testing should be performed? What treatment regimen is appropriate and what should be avoided? What are the risks or delayed complications from her illness? Are there special considerations for this or other patient populations?

[Experience of cytoflavin administration for treating acute carbon monoxide poisoning]

Results of an analysis of the efficiency of using cytoflavin, a drug possessing cytoprotective and antihypoxemic properties, in a group of 215 patients with a diagnosis of acute carbon monoxide poisoning in 2004-2010 are compared to analogous data for 215 patients with same diagnosis treated in 1999-2004 without cytoflavin administration. It is established that timely application of cytoflavin (against the standard treatment of CO poisoning) favored lower expressiveness of post-hypoxemic encephalopathythatis characteristic of the given pathology.

[Dynamic changes of hemorheology in rats after carbon monoxide poisoning]

OBJECTIVE

To investigate the startup detail of circulation dysfunction and its role in the progress of delayed neuropsychologic sequelae (DNS) after carbon monoxide (CO) poisoning with comparison with the model of ischemia-reperfusion.

METHODS

The ischemia-reperfusion rat model was established by Pulsinelli-Brierley method, and the CO poisoning rats model by i.p. injected with CO repeatedly respectively, and the rats were identified with DNS following the experiment of pathology and the ethnology.

RESULTS

The whole blood viscosity, plasma viscosity, hematocrit and fibrinogen increased significantly immediately after reperfusion, and recovered gradually with the ischemia-reperfusion rat model. The whole blood viscosity decreased significantly immediately after CO treated i.p. Especially at low shear rate, the hematocrit also declined remarkably in the early stage after CO treatment. But 1day later, these parameters turned to the trend of the ischemia-reperfusion rats. There was a prominent elevation of both indexes until the 14th day following CO injection i.p.

CONCLUSION

There are significantly sustained hyper-coagulation and hyper-viscosity with circulation in rats after CO poisoning compared with ischemia-reperfusion model during the period of DNS, which might contribute to increase cerebral circulation resistance, blocked blood flow, and deteriorate hypoxemia in progression of DNS.

The assessment of QT intervals in acute carbon monoxide poisoning

OBJECTIVE

Carbon monoxide (CO) poisoning is known to cause myocardial toxicity and life threatening arrhythmias. QT interval measured from electrocardiogram is an indirect measure of the heterogeneity of ventricular repolarization, which may contribute to ventricular arrhythmias. The purpose of the study was to investigate whether the carboxyhemoglobin (COHb) level may be related to the changes of QT, corrected QT (QTc), QT dispersion (QTd), corrected Qtd (QTdc) and cardiac enzymes during carbon monoxide poisoning.

METHODS

We conducted an observational study; 104 patients who had been diagnosed with CO intoxication were included in the study. Measurement of QT, QTc, QTd and QTdc intervals were performed form electrocardiogram on admission, 24 and 48 hours after admission. Cardiac enzymes were measured at each time-point. The myocardial perfusion scan was determined in all patients 1 week after admission.

RESULTS

The QT interval level in 24 h was significantly higher than admission level (p<0.001), additionally QTc interval levels in 24 h and 48 h were significantly lower than admission levels (p<0.001 and p<0.001, respectively). Carboxyhemoglobin level only significantly correlated with QT intervals (r=-0.288 ; p=0.019), troponin T (r=-0.297; p=0.007), and creatine kinase MB levels (r=0.262; p=0.020). As a result of ROC analysis the QT interval level was significantly powerful parameter to predict COHb (p=0.022).

CONCLUSION

Our data indicate COHb level correlated with QT intervals and cardiac enzymes. Clinicians should possibly avoid QT prolonging drugs and carefully monitor the QT, QTc, QTdc intervals in patients at high risk of cardiac disability due to high levels of COHb after CO poisoning.

Evidence for oxidative stress in the developing cerebellum of the rat after chronic mild carbon monoxide exposure (0.0025% in air)

BACKGROUND

The present study was designed to test the hypothesis that chronic very mild prenatal carbon monoxide (CO) exposure (25 parts per million) subverts the normal development of the rat cerebellar cortex. Studies at this chronic low CO exposure over the earliest periods of mammalian development have not been performed to date. Pregnant rats were exposed chronically to CO from gestational day E5 to E20. In the postnatal period, rat pups were grouped as follows: Group A: prenatal exposure to CO only; group B: prenatal exposure to CO then exposed to CO from postnatal day 5 (P5) to P20; group C: postnatal exposure only, from P5 to P20, and group D, controls (air without CO). At P20, immunocytochemical analyses of oxidative stress markers, and structural and functional proteins were assessed in the cerebellar cortex of the four groups. Quantitative real time PCR assays were performed for inducible (iNOS), neuronal (nNOS), and endothelial (eNOS) nitric oxide synthases.

RESULTS

Superoxide dismutase-1 (SOD1), SOD2, and hemeoxygenase-1 (HO-1) immunoreactivity increased in cells of the cerebellar cortex of CO-exposed pups. INOS and nitrotyrosine immunoreactivity also increased in blood vessels and Purkinje cells (PCs) of pups from group-A, B and C. By contrast, nNOS immunoreactivity decreased in PCs from group-B. Endothelial NOS immunoreactivity showed no changes in any CO-exposed group. The mRNA levels for iNOS were significantly up-regulated in the cerebellum of rats from group B; however, mRNA levels for nNOS and eNOS remained relatively unchanged in groups A, B and C. Ferritin-H immunoreactivity increased in group-B. Immunocytochemistry for neurofilaments (structural protein), synapsin-1 (functional protein), and glutamic acid decarboxylase (the enzyme responsible for the synthesis of the inhibitory neurotransmitter GABA), were decreased in groups A and B. Immunoreactivity for two calcium binding proteins, parvalbumin and calbindin, remained unchanged. The immunoreactivity of the astrocytic marker GFAP increased after prenatal exposure.

CONCLUSION

We conclude that exogenously supplied CO during the prenatal period promotes oxidative stress as indicated by the up-regulation of SOD-1, SOD-2, HO-1, Ferritin-H, and iNOS with increased nitrotyrosine in the rat cerebella suggesting that deleterious and protective mechanisms were activated. These changes correlate with reductions of proteins important to cerebellar function: pre-synaptic terminals proteins (synapsin-1), proteins for the maintenance of neuronal size, shape and axonal quality (neurofilaments) and protein involved in GABAergic neurotransmission (GAD). Increased GFAP immunoreactivity after prenatal CO-exposure suggests a glial mediated response to the constant presence of CO. There were differential responses to prenatal vs. postnatal CO exposure: Prenatal exposure seems to be more damaging; a feature exemplified by the persistence of markers indicating oxidative stress in pups at P20, following prenatal only CO-exposure. The continuation of this cellular environment up to day 20 after CO exposure suggests the condition is chronic. Postnatal exposure without prenatal exposure shows the least impact, whereas prenatal followed by postnatal exposure exhibits the most pronounced outcome among the groups.

Influence of carbon monoxide poisoning on the fetal heart monitor tracing: a report of 3 cases

BACKGROUND

The diagnosis of carbon monoxide poisoning in the third trimester of pregnancy requires an index of suspicion, and the appearance of the fetal heart monitor tracing may help in this regard.

CASES

Three cases of third-trimester acute carbon monoxide poisoning occurred. In each pregnancy, the fetal heart monitor tracing on admission was correlated with the maternal carboxyhemoglobin level, and how the pattern changed following the institution of therapy was analyzed.

CONCLUSION

In all 3 cases, the initial fetal heart rate pattern demonstrated decreased variability with an elevated baseline and an absence of accelerations and decelerations. Within 45-90 minutes of treatment onset, the baseline fetal heart rate dropped by 20-40 beats per minute, the variability became moderate, and accelerations occurred. Absent accelerations with minimal variability, if caused by uteroplacental insufficiency, are usually preceded by recurrent decelerations. Absent accelerations with minimal variability in the absence of recurrent decelerations may suggest another cause, of which carbon monoxide intoxication can be added to the differential, especially since this disorder often has nonspecific clinical symptoms.

A Case of Carbon Monoxide Poisoning with Thrombus in the Heart: A Case Report

Carbon monoxide is a nonirritant, odorless, colorless gas, and is lighter than air. It is an end product of the incomplete combustion of hydrocarbons. Its effects are most prominent in organs sensitive to oxygen deprivation, such as the heart, brain, and kidney. Carbon monoxide poisoning becomes more abundant in winter and at cold places. In Turkey, every year we see several deaths due to poisonous gas leaks from coal or wood stoves. Deaths particularly due to hypoxia-related central nervous system damage and ventricular dysrhythmias are observed. On the other hand, an association between thromboembolic accidents and carbon monoxide poisoning has been shown in literature. Thromboembolic accidents in the mesenteric, central nervous system, and extremities are reported. However, no atrial thrombus has been mentioned. In this study, a case of an atrial thrombus associated with carbon monoxide poisoning following a diagnosis of carbon monoxide poisoning and treatment in the emergency room is reported and the literature is revisited.

Cerebral blood flow and metabolism

To date, regional measurements of cerebral blood flow in humans have not been especially helpful in predicting the outcome of acute brain injury. The recent appearance within the medical environment of biologically significant pharmaceuticals labelled with the positron-emitting isotopes 15O, 13N and 11C has made possible the quantitative regional measurement of cerebral metabolism in humans. This advance, coupled with the development of radically new detection systems, will allow the safe measurement of truly regional blood flow and metabolism in humans in the near future. Such information is basic to an understanding of the pathophysiology of acute injury to the brain and the rational prediction of outcome in the individual case.

Analysis of the features of acute carbon monoxide poisoning and hyperbaric oxygen therapy in children

The aim of this study was to make a retrospective descriptive analysis of the features of children with acute carbon monoxide poisoning (COP). We evaluated 74 children (43 girls, 31 boys; age range 1 to 17.8 years) who were consecutively admitted to our emergency unit and hospitalized with accidental acute COP between June 2003 and June 2005. All patients received normobaric oxygen therapy until their carboxyhemoglobin (COHb) levels were decreased below 2% and their symptoms resolved. Thirty-eight of 74 patients (51.4%) also received hyperbaric oxygen (HBO) therapy as indicated by signs and symptoms or COHb levels. COHb levels were significantly higher and hospitalization period was longer in the children who had abnormal neurological findings (p<0.05 for both). All patients showed complete recovery without neurological sequelae except one who had visual impairment at discharge, and antiepileptic therapy was started because of epilepsy after seven months. Acute COP is an important health problem in our country, especially in winter, because of poorly functioning heating systems. The clinical spectrum including neurological findings varies during childhood. We suggest that HBO therapy could be used safely in children.

Health risk assessment of indoor air pollution in Finnish ice arenas

Poor indoor air quality and epidemic carbon monoxide (CO) and nitrogen dioxide (NO(2)) poisonings due to exhaust emissions from ice resurfacers have been continuously reported from enclosed ice arenas for over 30 years. The health risks in users of Finnish ice arenas were analysed in three ways: (1) evaluation of four cases of epidemic CO poisonings, (2) modelling the association between NO(2) exposure and respiratory symptoms among junior ice hockey players, and (3) estimation of the number of arena users at risk of breathing poor quality air due to non-compliance of ice arenas with recommended abatement measures. The common causes for the CO poisonings involving over 300 subjects were large emissions from propane-fuelled ice resurfacer, small arena volume, negligible ventilation, and very recent opening of the arena. Rhinitis (prevalence 18.3%) and cough (13.7%) during or after training or game were significantly associated with the estimated personal NO(2) exposure of young hockey players (n=793) to average concentrations ranging from 21 to 1176 microg/m(3) in their home arena. During a 6-year follow-up of an intensive information campaign the portion of electric resurfacers increased from 9% to 27%, and that of emission control technology on propane-fuelled resurfacers increased from 13% to 84%. The portion of inadequately ventilated arenas decreased from 34% to 25%. However, 48% of the investigated Finnish ice arenas (n=125) did not fully comply with the non-regulatory recommendations. Consequently, 20000 daily users of ice arenas were estimated to remain in 2001 at risk of breathing poor quality air. Modern small and inadequately ventilated ice arenas pose their users (mostly children and young adults) at risk of breathing poor quality air and suffering from acute adverse health effects. Governmental regulations are needed worldwide to ensure safe sports in enclosed ice arenas.

Carbon monoxide intoxication: an updated review

Carbon monoxide (CO), a highly toxic gas produced by incomplete combustion of hydrocarbons, is a relatively common cause of human injury. Human toxicity is often overlooked because CO is tasteless and odorless and its clinical symptoms and signs are non specific. The brain and the heart may be severely affected after CO exposure with carboxyhemoglobin (COHb) levels exceeding 20%. Damage occurs because the affinity of hemoglobin for CO is 210 times higher than for O(2). Hypoxic brain damage predominates in the cerebral cortex, cerebral white matter and basal ganglia, especially in the globus pallidus. Diagnosis requires clinical acumen and a high index of suspicion, combined with epidemiological data, clinical examination, analysis of ambient air CO and patient COHb levels; also required are cardiology evaluation including ECG as well as neurological evaluation including brain imaging (CT and/or MRI, MR spectroscopy), and neuropsychological testing. Although immediate O(2) breathing is sometimes an adequate treatment, hyperbaric oxygen therapy (HBO) is favored. Subsequently, only symptomatic therapy is available for the long-term sequelae of CO poisoning.

Hyperbaric oxygen and carbon monoxide poisoning: a critical review

CO is likely to be the most common cause of poisoning worldwide and often results in persistent neuropathologic and cognitive sequelae. While the displacement of oxygen from hemoglobin by CO has overshadowed the myriad mechanisms by which CO causes injury, mere oxygen displacement has endured as the etiology of CO poisonings and perpetuated a cascade of misdiagnosis, misunderstandings and confusion regarding how and when to treat CO poisoning. Hyperbaric oxygen benefits the brain more than normobaric oxygen by, e.g. improving energy metabolism, preventing lipid peroxidation and decreasing neutrophil adherence. Randomized controlled trials have definitively shown hyperbaric oxygen as the only efficacious therapy for acute CO poisoning if delayed neurological sequelae are to be minimized. Normobaric oxygen should not be used between multiple hyperbaric oxygen treatments as this can contribute to toxicity. Hyperbaric oxygen seems to also have potential in the delayed treatment of CO poisoning using multiple treatments of low dose of oxygen; however, oxygen dosing issues are not yet fully understood for either acute or delayed treatment. It would behoove medical decision-makers to embrace this important tool and make it more accessible as well as helping to disseminate to the medical community what is now known from the available literature.

[Carbon monoxide--poison or potential therapeutic?]

Carbon monoxide (CO) is much more than just a toxic gas. Carbon monoxide is produced endogenously by the enzyme heme oxygenase and has important functions under physiological and pathophysiological conditions. Recent studies suggested antioxidative, anti-inflammatory, antiproliferative, anti-apoptotic, and vasodilating characteristics. Regarding clinically-relevant diseases in anesthesiology and critical care medicine, such as adult respiratory distress syndrome (ARDS), sepsis, or during organ transplantation, cytoprotective properties have been demonstrated by low-dose CO in experimental models. In view of a potential CO application in future human studies, this review discusses what is known to date about CO as it relates to functional, protective and toxic aspects.

Serum levels of NT-ProBNP as an early cardiac marker of carbon monoxide poisoning

Acute carbon monoxide (CO) poisoning may cause cardiotoxicity. The natriuretic peptides, including atrial natriuretic peptide, brain natriuretic peptide (BNP), N-BNP, and NT-proBNP (N-terminal pro brain natriuretic peptide), are endogenous cardiac hormones that may be secreted upon myocardial stress. The aim of this study was to assess the plasma NT-proBNP level in acute CO poisoning and to compare it with healthy control. After approval by the ethical committee, 15 healthy controls and 15 patients admitted to the Gaziantep University Hospital (Gaziantep, Turkey) between January 2005 and July 2005 with the diagnosis of carbon monoxide poisoning were studied. Echocardiography was performed to all patients. Serum NT-proBNP, creatine kinase (CK), creatine kinase-MB (CK-MB), and troponin-T were also analyzed, along with the carboxyhemoglobin (COHb) level. The correlation between serum NT-proBNP and COHb level was investigated. Electrocardiography (ECG) was performed to all patients and healthy controls, and the results were compared. Differences in troponin, CK, and CK-MB levels were not statistically significant between groups (p > 0.05). The level of NT-proBNP and COHb were found to be increased in the study group. There was a positive correlation between the COHb and the NT-proBNP (r = 0.829, p < 0.01), and between the COHb and the CK (r = 0.394, p < 0.01). There was no difference between groups in other parameters, all of which were within normal range. Thus, in this study we showed that the plasma NT-proBNP level may contribute to the early diagnosis of cardiotoxicity in patients with carbon monoxide poisoning.