Pathophysiology and treatment of carbon monoxide poisoning

Carbon Monoxide Poisoning: From Occupational Health to Emergency Medicine

Carbon monoxide poisoning remains a leading cause of accidental poisoning worldwide (both at home and at work), and it is also a cause of suicidal poisoning. Such poisoning can arise following prolonged exposure to low levels of CO or following brief exposure to high concentrations of the gas. In fact, despite exposure limits, high safety standards, and the availability of CO alarms, nearly 50,000 people in the United States visit the emergency department each year due to poisoning. Additionally, CO poisoning in the United States causes up to 500 deaths each year. Despite the widespread nature of this form of poisoning, known about for centuries and whose damage mechanisms have been recognized (or rather hypothesized about) since the 1800s, early recognition, especially of late complications, and treatment remain a medical challenge. A well-designed therapeutic diagnostic process is necessary so that indication for hyperbaric or normobaric therapy is correctly made and so that patients are followed up even after acute exposure to diagnose late complications early. Furthermore, it is necessary to consider that in the setting of emergency medicine, CO poisoning can be part of a differential diagnosis along with other more frequent conditions, making its recognition difficult. The last thirty years have been marked by a significant increase in knowledge regarding the toxicity of CO, as well as its functioning and its importance at physiological concentrations in mammalian systems. This review, taking into account the significant progress made in recent years, aims to reconsider the pathogenicity of CO, which is not trivially just poisonous to tissues. A revision of the paradigm, especially as regards treatment and sequelae, appears necessary, and new studies should focus on this new point of view.

Correlation between Carboxyhemoglobin Levels Measured by Blood Gas Analysis and by Multiwave Pulse Oximetry

Carbon monoxide (CO) poisoning is difficult to diagnose owing to its nonspecific symptoms. Multiwave pulse oximetry can be used to quickly screen patients for CO poisoning. However, few studies have analyzed patients with CO poisoning who presented to the emergency department (ED). The primary aim of our study was to determine the correlation between COHb levels measured in blood gas analysis and COHb levels measured in multiwave pulse oximetry. Secondary aims were the sensitivity and specificity of the COHb level cutoff value using multiwave pulse oximetry to predict a 25% COHb level in blood gas analysis. This single-center retrospective observational study included patients with CO poisoning who visited the ED of a university-affiliated hospital in Seoul, Korea between July 2021 and June 2023. COHb poisoning was determined using blood gas analysis and multiwave pulse oximetry. The correlation of COHb levels between the two tests was evaluated using correlation analysis. The area under the receiver operating characteristic curve (AUC) of multiwave pulse oximetry was calculated to predict COHb levels from the blood gas analysis. The optimal cutoff values, sensitivity, and specificity of COHb were determined. A total of 224 patients who had COHb levels measured using both multiwave pulse oximetry and blood gas analysis were included in the analysis. In the correlation analysis, COHb showed a high positive correlation with COHb measured using blood gas analysis (Spearman correlation coefficient = 0.86, p < 0.001). The AUC of COHb measured by multiwave pulse oximetry to predict 25% of the COHb level (which can be an indication of hyperbaric oxygen treatment) measured by blood gas analysis was 0.916. When the COHb levels measured with multiwave pulse oximetry were 20% the sensitivity was 81% and the specificity was 83%, and when the COHb levels were 25% the sensitivity was 50% and the specificity was 95%. The COHb value measured using multiwave pulse oximetry blood gas analysis showed a high correlation. However, additional research using large-scale studies is required for validation.

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.

Plight of CORMs: The unreliability of four commercially available CO-releasing molecules, CORM-2, CORM-3, CORM-A1, and CORM-401, in studying CO biology

Carbon monoxide (CO) is an endogenously produced gaseous signaling molecule with demonstrated pharmacological effects. In studying CO biology, three delivery forms have been used: CO gas, CO in solution, and CO donors of various types. Among the CO donors, four carbonyl complexes with either a transition metal ion or borane (BH3) (termed CO-releasing molecules or CORMs) have played the most prominent roles appearing in over 650 publications. These are CORM-2, CORM-3, CORM-A1, and CORM-401. Intriguingly, there have been unique biology findings that were only observed with these CORMs, but not CO gas; yet these properties were often attributed to CO, raising puzzling questions as to why CO source would make such a fundamental difference in terms of CO biology. Recent years have seen a large number of reports of chemical reactivity (e.g., catalase-like activity, reaction with thiol, and reduction of NAD(P)+) and demonstrated CO-independent biological activity for these four CORMs. Further, CORM-A1 releases CO in an idiosyncratic fashion; CO release from CORM-401 is strongly influenced or even dependent on reaction with an oxidant and/or a nucleophile; CORM-2 mostly releases CO2, not CO, after a water-gas shift reaction except in the presence of a strong nucleophile; and CORM-3 does not release CO except in the presence of a strong nucleophile. All these beg the question as to what constitutes an appropriate CO donor for studying CO biology. This review critically summarizes literature findings related to these aspects, with the aim of helping result interpretation when using these CORMs and development of essential criteria for an appropriate donor for studying CO biology.

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.

A mitochondria-targeted fluorescent probe for imaging of endogenous carbon monoxide in living cells

Carbon monoxide (CO), a vital gasotransmitter, plays critical functions in many physiological processes. Mitochondrial CO is closely related to mitochondrial respiration, thus the detection and imaging of mitochondrial CO in living cells is very important and has attracted much attention recently. In this paper, we developed a hemicyanine-based off-on fluorescent probe, CO-H1, which was used for monitoring endogenous mitochondrial CO levels in living cells. After reacted with CO in the presence of PdCl₂, the fluorescence of CO-H1 was enhanced notably, accompanied by a significant red shift of absorption. CO-H1 exhibits low cytotoxicity, high sensitivity (detection limit of 0.048 μM), and good selectivity for CO. When incubated with living cells, probe CO-H1 mainly entered the mitochondria. CO-H1 was successfully applied to imaging the exogenous/endogenous mitochondrial CO in living cells, suggesting its potential application for further studying the biological functions of mitochondrial CO in living cells.

Atypical Presentation of Carbon Monoxide Poisoning With Aphasia

We present a patient with carbon monoxide poisoning with a single focal neurological deficit. The patient was found by emergency medical services (EMS) to be resting in his truck with a generator running nearby. On arrival, the patient was hemodynamically stable. The patient was aphasic but did not exhibit any other focal or lateralizing deficits. He was able to communicate by writing clearly and coherently on a sheet of paper. His initial carboxyhemoglobin was 29%, confirming the diagnosis of carbon monoxide poisoning. He was treated with 100% O₂ via a non-rebreather mask and regained his speech during his ED (emergency department) course. The patient was ultimately hospitalized for continued oxygen treatment and serial examinations. This case highlights the varied presenting symptoms of carbon monoxide poisoning as well as the importance of including a broad differential diagnosis while working up patients with a focal neurologic deficit.

An artificial intelligence algorithm for analyzing globus pallidus necrosis after carbon monoxide intoxication

Globus pallidus necrosis (GPN) is one of typical neurological imaging features in patients with carbon monoxide (CO) poisoning. Current clinical guideline recommends neurological imaging examination for CO-intoxicated patients with conscious disturbance rather than routine screening, which may lead to undiagnosed GPN. We aimed to develop an artificial intelligence algorithm for predicting GPN in CO intoxication patients. We included CO intoxication patients with neurological images between 2000 and 2019 in Chang Gung Memorial Hospital. We collected 41 clinical and laboratory parameters on the first day of admission for algorithm development. We used fivefold cross validation and applied several machine learning algorithms. Random forest classifier (RFC) provided the best predictive performance in our cohort. Among the 261 patients with CO intoxication, 52 patients presented with GPN. The artificial intelligence algorithm using the RFC-based AI model achieved an accuracy = 79.2 ± 2.6%, sensitivity = 77.7%, precision score = 81.9 ± 3.4%, and F1 score = 73.2 ± 1.8%. The area under receiver operating characteristic was approximately 0.64. Top five weighted variables were Platelet count, carboxyhemoglobin, Glasgow Coma scale, creatinine, and hemoglobin. Our RFC-based algorithm is the first to predict GPN in patients with CO intoxication and provides fair predictive ability. Further studies are needed to validate our findings.

Prospective Study Investigating Change in Carboxyhemoglobin Blood Level During Operative Hysteroscopy

STUDY OBJECTIVES

To evaluate whether the use of radiofrequency energy during resectoscopy leads to increases in patient blood levels of carboxyhemoglobin (COHb) and investigate procedural variables associated with these elevations.

DESIGN

A prospective cross-sectional study of 40 subjects undergoing a hysteroscopic procedure using bipolar radiofrequency energy.

SETTING, PATIENTS, AND INTERVENTIONS

The study was conducted at an ambulatory surgery center. Procedures for uterine leiomyoma, septa, products of conception, or a combination of these pathologies were included. We measured blood COHb levels before and immediately after the surgery. Abnormal postoperative COHb level was defined as an increase of plasma COHb ≥3.0%. All patients with abnormal postoperative levels were contacted and screened for carbon monoxide toxicity symptoms. Summary statistics included frequency for categorical variables and averages for continuous variables. p values were reported without modification.

MEASUREMENTS AND MAIN RESULTS

A total of 17.5% of subjects met the criteria for abnormal postoperative COHb levels. None of these subjects reported symptoms of carbon monoxide toxicity. One subject with an elevated postoperative COHb level had intraoperative hemodynamic changes possibly related to COHb elevation. An abnormal postoperative COHb level was associated with a higher fluid deficit (p = .024) and greater myoma volume (p = .04).

CONCLUSION

This study demonstrates that systemic absorption of carbon monoxide is a reproducible phenomenon in hysteroscopic resections using bipolar diathermy. Greater absorption is associated with a higher fluid deficit and greater myoma volume. Although none of the subjects with an abnormal increase screened positive for symptoms in the postoperative setting and only 1 experienced hemodynamic changes intraoperatively, our study looked at a healthy and young patient population. More research is needed on the safety of this COHb exposure in patients with medical comorbidities. Special consideration should be given to the possibility of carbon monoxide absorption and the uncertain long-term effects when planning extensive hysteroscopic resections.

Naphthalimide derivatives as fluorescent probes for imaging endogenous gasotransmitters

Gasotransmitters have gained significant recognition attributed to their evident biological impacts, and is accepted as a promising and less-explored area with immense research scope. The three-member family comprising of nitric oxide, carbon monoxide and hydrogen sulphide as endogenous gaseous signaling molecules have been found to elicit a plethora of crucial biological functions, spawning a new research area. The sensing of these small molecules is vital to gain deeper insights into their functions, as they can act both as a friend or a foe in mammalian systems. The initial sections of the review present the physiological and pathophysiological roles of these endogenous gas transmitters and their synergistic interactions. Further, various detection approaches, especially the usage of fascinating features of 1,8-naphthalimide as fluorescent probe in the detection and monitoring of these small signaling molecules are highlighted. The current limitations and the future scope of improving the sensing of the three gasotransmitters are also discussed.

The Outcomes of Inhalation Injuries in Lesser Burns: Still a Deadly Injury

BACKGROUND

Although it has been widely proposed that inhalation injuries worsen burn outcomes, large-scale studies have yet to demonstrate the exact relationship. This study proposes inhalation injuries as an independent risk factor that worsens burn outcomes.

METHODS

A retrospective review of the American Burn Association Registry from 2002 to 2011 was conducted. Inclusion criteria included burn patients with a total body surface area (TBSA) of less than 15% and adequate data recording of the inhalation injury within the registry. Patients were stratified into 2 groups: inhalation injuries (group 1) vs non-inhalation injuries (group 2). Outcome measures included in-hospital mortality rate, hospital length of stay (LOS), intensive care unit (ICU) LOS, and days on a ventilator.

RESULTS

A total of 93781 burn patients met the inclusion criteria. There were 4204 patients in group 1 and 89577 patients in group 2. There was no statistically significant difference between the 2 groups in terms of TBSA, with 3.50% in group 1 and 3.58% in group 2. There was a significantly higher ICU LOS at 8.55 days in group 1 compared to 6.27 days in group 2. There was a significantly higher hospital LOS at 11.48 days in group 1 compared to 6.27 days in group 2. The in-hospital mortality was significantly higher in group 1 at 8.54% vs group 2 at 1.42%.

CONCLUSION

The presence of inhalation injury may be a predictor of increased mortality and poor outcome in burn patients, even in those with small sized burns.

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.

Carbon Monoxide Poisoning

Carbon monoxide is a colorless, odorless, highly toxic gas primarily produced through the incomplete combustion of organic material. Carbon monoxide binds to hemoglobin and other heme molecules, causing tissue hypoxia and oxidative stress. Symptoms of carbon monoxide poisoning can vary from a mild headache to critical illness, which can make diagnosis difficult. When there is concern for possible carbon monoxide poisoning, the diagnosis can be made via blood co-oximetry. The primary treatment for patients with carbon monoxide poisoning is supplemental oxygen, usually delivered via a nonrebreather mask. Hyperbaric oxygen can also be used, but the exact indications are controversial.

Chronic carbon monoxide poisoning. A report of two cases

If acute carbon monoxide poisoning is a well-known emergency situation, this is not the case for chronic poisoning. The missed diagnosis of acute CO poisoning is a well-known problem but the identification of a chronic poisoning is very challenging. Knowledge and awareness of chronic poisoning is less defined and probably there is a great number of patients with undiagnosed chronic CO poisoning. It is possible that in case of missed diagnosis because of non-specific symptoms, chronic CO poisoning could be responsible for significant morbidity. We describe the case of a married couple who were rescued almost simultaneously, to show this clinical condition.

Metabolic changes during carbon monoxide poisoning: An experimental study

Carbon monoxide (CO) is the leading cause of death by poisoning worldwide. The aim was to explore the effects of mild and severe poisoning on blood gas parameters and metabolites. Eleven pigs were exposed to CO intoxication and had blood collected before and during poisoning. Mild CO poisoning (carboxyhaemoglobin, COHb 35.2 ± 7.9%) was achieved at 32 ± 13 minutes, and severe poisoning (69.3 ± 10.2% COHb) at 64 ± 23 minutes from baseline (2.9 ± 0.5% COHb). Blood gas parameters and metabolites were measured on a blood gas analyser and nuclear magnetic resonance spectrometer, respectively. Unsupervised principal component, analysis of variance and Pearson's correlation tests were applied. A P-value ≤ .05 was considered statistically significant. Mild poisoning resulted in a 28.4% drop in oxyhaemoglobin (OHb) and 12-fold increase in COHb, while severe poisoning in a 65% drop in OHb and 24-fold increase in COHb. Among others, metabolites implicated in regulation of metabolic acidosis (lactate, P < .0001), energy balance (pyruvate, P < .0001; 3-hydroxybutyrc acid, P = .01), respiration (citrate, P = .007; succinate, P = .0003; fumarate, P < .0001), lipid metabolism (glycerol, P = .002; choline, P = .0002) and antioxidant-oxidant balance (glutathione, P = .03; hypoxanthine, P < .0001) were altered, especially during severe poisoning. Our study adds new insights into the deranged metabolism of CO poisoning and leads the way for further investigation.

Hyperbaric oxygen therapy in carbon monoxide poisoning in pregnancy: Maternal and fetal outcome

OBJECTIVE

Closer monitoring and treatment is vital for pregnant carbon monoxide (CO) poisoning cases due to fetal poisoning component. Permanent damage can occur in both the mother and the baby. It may cause stillbirth even though no serious clinical symptoms occur in the mother. Hyperbaric oxygen (HBO) treatment is advised for all pregnant patients regardless of their clinical symptoms. Pregnant CO poisoning patients that received HBO treatment and their fetal status were evaluated in this study.

METHODS

Pregnant patients poisoned with CO treated in the same hyperbaric clinic were evaluated. Pregnant patients that received HBO treatment in a multiplace chamber were evaluated in terms of clinical status, demographic structure, laboratory tests, fetal effects and progress of the fetus until birth and 6 months postpartum.

RESULTS

A total number of 32 pregnant cases were treated. COHb values were over 20% (min 6.9- max 40.2) in 23 patients, 11 patients had a history of syncope. All patients took HBO treatment under 2.4 ATA pressure for 120 min. 3 patients received more than 1 session of HBO treatments due to fetal stress; all other cases took 1 session of HBO treatment. No spontaneous abortus occurred in early follow-ups; only 4 babies were born prematurely. 2 of the babies were lost in the early phases after birth, due to causes non-related to CO poisoning complications (cyanotic heart disease, necrotising enterocolitis). No significant difference were observed in the comparison of laboratory results of patients with syncope and of those who did not have syncope and comparison of patients with COHb value higher than 20% and patients with COHb value lower than 20% (p > 0.05).

CONCLUSION

HBO is not advisable for pregnant patients except for CO poisoning. In this study it is observed that HBO treatment under 2.4 ATA pressure for 120 min has no harmful effects on the mother and the fetus. It is observed that continuation of HBO treatment in the cases with fetal distress findings has beneficial effects. COHb levels and syncope were shown to have no significant effect on clinical symptoms and on blood tests.

Mitochondria-targetable ratiometric fluorescence probe for carbon monoxide based on naphthalimide derivatives

The design of ratiometric probes for imaging of carbon monoxide (CO) in subcellular organelles is critical to elucidate its biological and pathological functions. In this work, we establish a ratiometric fluorescent probe (Mito-NIB-CO) for imaging of CO in mitochondria. The mitochondria-targeting unit (triphenylphosphonium moiety) and CO-responsive unit (allyl ether moiety) are covalently linking into the single molecule (Mito-NIB-CO) to achieve the multifunctional effect. Upon being treated with CO, Mito-NIB-CO underwent the cleavage of allyl ether element in the presence of PdCl₂, resulting in the structural and spectral conversion. This characteristic afforded Mito-NIB-CO to be a ratiometric probe for CO with two fluorescent emission bands. Additionally, the probe Mito-NIB-CO exhibited other distinct merits, including preeminent selectivity and sensitivity. What's more, profiting from triphenylphosphonium moiety, the probe Mito-NIB-CO can specifically target the mitochondria and realize quantitative detection of exogenous/endogenous CO in mitochondria. Graphical abstract.

Towards "CO in a pill": Pharmacokinetic studies of carbon monoxide prodrugs in mice

Carbon monoxide (CO) is a known endogenous signaling molecule with potential therapeutic indications in treating inflammation, cancer, neuroprotection, and sickle cell disease among many others. One of the hurdles in using CO as a therapeutic agent is the development of pharmaceutically acceptable delivery forms for various indications. Along this line, we have developed organic CO prodrugs that allow for packing this gaseous molecule into a dosage form for the goal of "carbon monoxide in a pill." This should enable non-inhalation administration including oral and intravenous routes. These prodrugs have previously demonstrated efficacy in multiple animal models. To further understand the CO delivery efficiency of these prodrugs in relation to their efficacy, we undertook the first pharmacokinetic studies on these prodrugs. In doing so, we selected five representative prodrugs with different CO release kinetics and examined their pharmacokinetics after administration via oral, intraperitoneal, and intravenous routes. It was found that all three routes were able to elevate systemic CO level with delivery efficiency in the order of intravenous, oral, and intraperitoneal routes. CO prodrugs and their CO-released products were readily cleared from the circulation. CO prodrugs demonstrate promising pharmaceutical properties in terms of oral CO delivery and minimal drug accumulation in the body. This represents the very first study of the interplay among CO release kinetics, CO prodrug clearance, route of administration, and CO delivery efficiency.

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.

Admission Carboxyhemoglobin: Is It a Marker for Burn Patient Outcomes?

BACKGROUND

Carbon monoxide is a gas produced by the combustion of hydrocarbon products that binds to heme molecules, 240 times more than oxygen, producing carboxyhemoglobin (COHb). As a result of its high affinity, there is shift of the oxyhemoglobin dissociation curve, compromising oxygen transport and delivery to tissues. Our study aim was to evaluate COHb elevation on admission as a predictor of worse outcomes in burn patients.

METHODS

This is a 10-year retrospective review of the American Burn Association Burn Registry from 2002 to 2011. We stratified the patients into 2 groups: adult patients with normal COHb on admission (group 1) versus elevated COHb (group 2). Elevated COHb levels were defined as greater than 10% on the first arterial blood gas. Outcome measures included in-hospital mortality rate, hospital length of stay (LOS), intensive care unit LOS (ICU-LOS), and ventilator days. χ and t test analyses were used with significance defined as a P value of less than 0.05.

RESULTS

A total of 6365 burn patients meet our inclusion criteria. There were 5775 patients in group 1 and 590 patients in group 2. Group 1 had an average age of 39.29 years compared with 42.62 years in group 2. The total body surface area was higher in group 1 compared with group 2 (6.24 vs 4.65) and with a statistically significant increase in partial thickness burns at 4.97 in group 1 compared with 3.27 in group 2. There was no statistically significant difference between the 2 groups in terms of full thickness total body surface area. The hospital LOS was significantly higher in group 2 compared with group 1 (15.34 vs 9.66). There was a significantly higher ICU-LOS at 12.89 days in group 2 compared with 4.01 in the group 1 (P = 0.0001, t test). There were higher ventilator days in group 2 at 9.23 than those in group 1 at 2.05 (P < 0.0001, t test). The in-hospital mortality was also significantly higher in group 2 at 15.59% than in group 1 at 1.33% (P = 0.0001, χ).

CONCLUSIONS

Elevated COHb on admission was associated with an increased hospital and ICU-LOS, average ventilator days, and in-hospital mortality. The presence of elevated COHb of greater than 10% on an initial arterial blood gas suggests worse outcomes and increased need of resource utilization during the index hospital admission.

Assessment of serum glucose/potassium ratio as a predictor for delayed neuropsychiatric syndrome of carbon monoxide poisoning

INTRODUCTION

Carbon monoxide (CO) poisoning is a crucial cause of delayed neuropsychiatric syndrome (DNS). However, most biomarkers are not satisfactory for the prediction of DNS caused by CO poisoning. Thus, we evaluated the adequacy of the serum glucose/potassium (GLU/K) ratio, which may be an easy, quick, and readily available parameter that can be used in the emergency department for predicting DNS.

METHODS

We evaluated 281 patients who were admitted to our emergency department between January 2012 and December 2018. The patients were divided into two groups: DNS (+) and DNS (-). The GLU/K was compared for the groups.

RESULTS

Glucose, blood urea nitrogen, carboxyhemoglobin, and GLU/K ratios of patients in the DNS (+) group were statistically significantly higher than those patients in DNS (-) group (140 ± 34 vs. 110 ± 24, p < 0.001; 17.58 ± 6.14 vs. 14.27 ± 5.08, p = 0.003; 29 ± 5.1 vs. 18.9 ± 7.6, p < 0.001; and 38.35 ± 10.11 vs. 28.65 ± 6.53, p < 0.001, respectively). The area under the curve for GLU/K to predict DNS was measured as 0.791, and 35.9 as a cut-off value had 63.6% sensitivity and 89.6% specificity.

CONCLUSIONS

DNS development in CO poisoning is a serious and feared complication. We suggest that the GLU/K ratio has a high potential as a rapid, easy preliminary marker for the exclusion of patients who will not subsequently develop DNS.

Initial Management of Poisoned Patient

How to cite this article: Chandran J, Krishna B. Initial Management of Poisoned Patient. Indian J Crit Care Med 2019;23(Suppl 4):S234-S240.

Carbon Monoxide Poisoning Effectively Treated with High-flow Nasal Cannula

Carbon monoxide (CO) poisoning is typically treated by administration of oxygen via non-rebreather mask (NRB). High-flow nasal cannula (HFNC) is an alternative to NRB in a variety of disease states. We report a case of the novel use of HFNC in the treatment of acute CO poisoning. A 29-year-old man presented with a carboxyhemoglobin (COHb) level of 29.8%. He was treated with HFNC, and COHb levels declined to 5.4% in 230 minutes. Given several theoretical advantages of HFNC relative to NRB, HFNC is a potential option for use in the treatment of CO poisoning.

Air pollution exposure associates with increased risk of neonatal jaundice

Clinical experience suggests increased incidences of neonatal jaundice when air quality worsens, yet no studies have quantified this relationship. Here we reports investigations in 25,782 newborns showing an increase in newborn's bilirubin levels, the indicator of neonatal jaundice risk, by 0.076 (95% CI: 0.027-0.125), 0.029 (0.014-0.044) and 0.009 (95% CI: 0.002-0.016) mg/dL per μg/m3 for PM2.5 exposure in the concentration ranges of 10-35, 35-75 and 75-200 μg/m3, respectively. The response is 0.094 (0.077-0.111) and 0.161 (0.07-0.252) mg/dL per μg/m3 for SO2 exposure at 10-15 and above 15 μg/m3, respectively, and 0.351 (0.314-0.388) mg/dL per mg/m3 for CO exposure. Bilirubin levels increase linearly with exposure time between 0 and 48 h. Positive relationship between maternal exposure and newborn bilirubin level is also quantitated. The jaundice-pollution relationship is not affected by top-of-atmosphere incident solar irradiance and atmospheric visibility. Improving air quality may therefore be key to lowering the neonatal jaundice risk.

A 5-year Assessment on Carbon Monoxide Poisoning in a Referral Center in Tehran-Iran

Background:

Carbon monoxide (CO) poisoning results in hundreds of deaths and thousands of emergency department visits all over Iran annually. In this study, we aim to provide an epidemiologic analysis of this poisoning in different consciousness levels.

Methods:

This single-center retrospective study was conducted at a referral poison center from March 21, 2007 to March 19, 2012 in Tehran, Iran. All CO poisoned children and adults who hospitalized were evaluated based on their on-arrival consciousness level.

Results:

Two-hundred-sixty patients with pure CO poisoning were enrolled with the majority of males (55.4%). CO exposure was unintentional in 99.6% of cases. The average period between CO exposure and the patients' hospital admission was 6.4 hours (SD = 11.2). Most of the toxicities had occurred at home (73.5%). On arrival acid-base status revealed respiratory acidosis cases in 11.9% of cases. Central nervous system imaging revealed 6.2% abnormal finding. Typically, patients presented with vomiting (25.8%), nausea (22.7%), and dizziness (11.3%). Twenty-nine patients (11.2%) needed intubation and mechanical ventilation. Thirty-six patients admitted to ICU with a median [IQR] hospital stay of 6 [2, 18] days. Ultimately, 202 (78.6%) patients discharged and 47 (18.3%) left the hospital against medical advice, 5 (1.9%) died, and 10 (3.8%) experienced sequellae. Two patients (0.8%), were transferred to other hospitals for specialized care.

Conclusions:

The incidence and mortality rate of CO poisoning in the current study are still higher than many other parts of the world. Ongoing health prevention strategies are not efficiently working. Hence, constant public education and warning about CO toxicity should be highlighted.

Predicting of neuropsychosis in carbon monoxide poisoning according to the plasma troponin, COHb, RDW and MPV levels: Neuropsychoses in carbon monoxide poisoning

OBJECTIVE

Carbon monoxide (CO) poisoning is very common worldwide. In this study, we aimed to evaluate the predictivity of neuro psychosis in carbon monoxide poisoning by the admission levels of red cell distribution (RDW), mean platelet volume (MPV) and troponin I levels which can be measured quickly and easily in the emergency department (ED).

PATIENTS AND METHODS

This single center observational study included a total of 216 consecutive patients who presented to the ED due to CO poisoning between January 2009 and December 2013. The diagnosis of CO poisoning was made according to the medical history and carboxyhemoglobin (COHb) level of >5%. According to the carboxyhemoglobin levels, the patients were classified as mildly (COHb < 20%) and severely poisoned (COHb > 20%). In addition, patients were divided into 2 groups, i.e., those with positive (>0.05 ng/mL for our laboratory) and negative (<0.05 ng/mL for our laboratory) troponin levels.

RESULTS

Patients mean age was 52.58 ± 10.58. 57.9% of the patients had high troponin levels and 51.9% were poisoned severely according to COHb levels. Patients with positive troponin and COHb had longer CO exposure time and higher neutrophil, lymphocyte, mean platelet volume (MPV), COHb and red cell distribution width (RDW) levels at the index admission following CO poisoning than patients with negative troponin (p < 0.05). Age, COHb level, CO exposure time, MPV and RDW (p = 0.001, p < 0.05) remained associated with an increased risk of troponin positivity following adjustment for the variables that were statistically significant.

CONCLUSIONS

In patients presenting to the ED with CO poisoning, RDW and MPV can be helpful for risk stratification of neuropsychosis.

Mitochondria-Targetable Ratiometric Time-Gated Luminescence Probe for Carbon Monoxide Based on Lanthanide Complexes

As a critical gasotransmitter, carbon monoxide (CO) has been demonstrated to be related with mitochondrial respiration, but the monitoring of CO in mitochondria remains a great challenge. In this work, a unique ratiometric time-gated luminescence (TGL) probe, Mito-NBTTA-Tb³⁺/Eu³⁺, that can specifically respond to mitochondrial CO has been developed. The probe was designed by incorporating a mitochondria-targeting moiety, triphenylphosphonium, into a CO-activatable terpyridine polyacid derivative, 4'-(4-nitrobenzyloxy-2,2':6',2''-terpyridine-6,6''-diyl) bis(methylenenitrilo) tetrakis(acetic acid), for coordinating to Eu³⁺ and Tb³⁺ ions to construct lanthanide complex-based probe for ratiometric TGL detection of CO. Upon reaction with CO, accompanied by the conversion of nitro group to amino group, a 1,6-rearrangement-elimination reaction occurs, which leads to the cleavage of 4-nitrobenzyl group from Mito-NBTTA-Tb³⁺/Eu³⁺, resulting in the significant increase of Tb³⁺ emission at 540 nm and moderate decrease of Eu³⁺ emission at 610 nm. After the reaction, the I₅₄₀/ I₆₁₀ ratio was found to be 48-fold enhanced. This feature allowed Mito-NBTTA-Tb³⁺/Eu³⁺ to be employed as a ratiometric TGL probe for CO detection with the I₅₄₀/ I₆₁₀ ratio as a signal. In addition, the probe showed outstanding mitochondria-localization characteristic, which enabled the probe to be successfully applied to imaging CO within mitochondria of living cells under TGL and ratiometric modes. The application of Mito-NBTTA-Tb³⁺/Eu³⁺ was demonstrated by the visualization and quantitative detection of exogenous and endogenous CO in living cells and mouse liver tissue slices, as well as in living Daphnia magna and mice. All of the results suggested the potential of Mito-NBTTA-Tb³⁺/Eu³⁺ for the quantitative monitoring of CO in vitro and in vivo.

Carbon monoxide poisoning in a young, healthy patient: A case study of heart failure recovery after Hyperbaric Oxygenation Treatment

The effectiveness of hyperbaric oxygen treatment for acute cardiac diseases is unknown. Similarly, the effectiveness of hyperbaric oxygen treatment for carbon monoxide intoxication is also unknown, particularly for cases in which carboxyhemoglobin (COHb) levels return to normal. Our case study revolved around a healthy twenty-year-old male patient, who suffered from carbon monoxide intoxication. The patient presented to the Emergency Department unconscious. Blood workup revealed significant carbon monoxide intoxication and cardiac injury (COHb = 41%, troponin T = 0.38 ng/dl, ST depression). He was intubated and transferred to a specialist Centre for hyperbaric oxygenation treatment, whilst mechanically ventilated. COHb on arrival (5 hours later) was 4.3%. First echocardiography revealed estimated ejection fraction of 30%, moderate-severe left ventricular dysfunction and global hypokinesis. Patient received 3 rounds of HBOT; each round was 2.4 ATA, 100% O₂ and 120 minutes long within the following 24 hours. Afterwards, the patient was successfully extubated. Three days later, a second echocardiography showed remarkable improvement with normal left ventricular size and function. The patient discharged the following day without complaints or the need for long-term medication. Hyperbaric treatment for carbon monoxide intoxication with compromised cardiac function should be considered even when carboxyhaemoglobin levels have returned to normal. This is due to mitochondrial impairment caused by carbon monoxide intoxication that eventually can lead to significant cardiac deterioration.

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.

Acute effects of air pollution on spontaneous abortion, premature delivery, and stillbirth in Ahvaz, Iran: a time-series study

Living in areas with high air pollution may have adverse effects on human health. There are few studies about the association between breathing polluted air and adverse pregnancy outcomes in the Middle East. The aim of this study was to determine the relationship between air pollution and spontaneous abortion, premature birth, and stillbirth in Ahvaz. A time-series study was conducted. Data about spontaneous abortion, premature deliveries, and stillbirth was collected from Ahvaz Imam Khomeini Hospital. Air pollution data including NO, CO, NO₂, PM₁₀, SO₂, O₃, and climate data were, respectively, collected from the Environmental Protection Agency and the Khuzestan Province Meteorology Office from March 2008 until March 2015. The relationship between air pollutants with the number of abortions, premature births, and stillbirths was found using a quasi-Poisson distributed lag model, adjusted by trend, seasonality, temperature, relative humidity, weekdays, and holidays. The average daily dust in Ahvaz on 7.2% days of the year was higher than 500 μg/m³ (very dangerous). Findings from this study indicate a significant association between each 10-unit increase in SO₂ and spontaneous abortion in lag 0 and 9 days. There was a significant relation between each 10-unit increase in NO₂ and CO, and premature birth in lag 0. Also, we found a significant association between each 10-unit increase in CO and premature delivery in lag 1; PM₁₀ and premature delivery in lags 10, 11, and 12; and NO and premature delivery in lags 3, 4, 10, 11, 12, and 13 (p value < 0.05). Contact with polluted air during pregnancy may increase adverse pregnancy outcomes and stillbirth. Pregnant women should avoid polluted air.

Normal carboxyhaemoglobin level in carbon monoxide poisoning treated with hyperbaric oxygen therapy

Throughout the world both intentional and inadvertent exposure to carbon monoxide (CO) remains an important public health issue. While CO poisoning can be lethal, the morbidity is predominantly due to nervous system injury. A previously healthy 22-year-old woman was found unconscious at home by her sister. Her parents were found dead in the house with a recent history of a dysfunctional furnace. She was presumed to have CO poisoning despite an initial carboxyhaemoglobin level of 2.5%. Patient had both clinical and radiological evidence of neurological damage. However, with multiple sessions of hyperbaric oxygen (HBO) therapy she recovered to a near normal functional status. There is no consensus that exists among treating physicians about the role of hyperbaric oxygen in management of neurological injury. The case described here has significant neurological damage related to CO exposure but improved after HBO therapy.

Risk Factors and Outcome Analysis in Children with Carbon Monoxide Poisoning

BACKGROUND

Carbon monoxide (CO) poisoning is one of the common causes of poisoning in patients and can result in significant morbidity and mortality. However, few studies have focused on the pediatric group.

METHODS

We retrospectively reviewed children (age < 18 years) with CO poisoning from nonfire accidents at a tertiary medical center in Taiwan from 2002 to 2010. We analyzed the patients' characteristics, management, and outcome; compared the data of patients who received hyperbaric oxygen (HBO) to those who received normobaric oxygen (NBO) therapy; and identified the ri0sk factors for patients who developed delayed neurological sequelae (DNS) or permanent neurological sequelae (PNS).

RESULTS

A total of 81 children were enrolled. The annual case number increased from five cases in 2002 to 20 in 2010, particularly during the cold months (December to February). The most common source of exposure was an indoor heating system (54.3%). The most common presenting symptoms were vomiting (32.1%) and consciousness changes (30.9%). HBO treatment tended to be administered to patients with a higher initial COHb (%) (p < 0.001), an initial Glasgow coma scale change (p < 0.001), and admission to the hospital (p = 0.002). After multivariate analysis, treatment in the intensive care unit because of prolonged loss of consciousness (p = 0.002) was the only independent risk factor for patients with DNS; only rescue by a ventilator (p < 0.001) was an independent risk factor for patients with PNS. In comparison to the NBO therapy, HBO treatment did not show benefit or harm to patients according to the incidence of inducing DNS or PNS after multivariate analysis.

CONCLUSION

For those with treatment in the intensive care unit because of prolonged loss of consciousness and rescue by a ventilator, special attention should be given and follow-up should be performed to determine whether DNS or PNS occurs, particularly epilepsy and cognitive deficits.

Non-ST elevation myocardial infarction secondary to carbon monoxide intoxication

Carbon monoxide poisoning has been documented in literature to cause severe neurological and tissue toxicity within the body. However, cardiotoxicity is often overlooked, but not uncommon. Previous research studies and case reports have revealed a significant relationship between carbon monoxide intoxication and myocardial ischemic events. We report a case of a 48-year-old male, who was exposed to severe smoke inhalation due to a house fire and subsequently developed a non-ST elevation myocardial infarction. Ischemic changes were evident on electrocardiogram, which demonstrated T-wave inversion in lead III and ST-segment depression in leads V4-V6. Elevated cardiac enzymes were also present. After standard treatment for an acute cardiac event, the patient fully recovered. This case demonstrates that myocardial ischemic changes due to carbon monoxide poisoning may be reversible if recognized in early stages and treated appropriately, thus reminding physicians that a proper cardiovascular examination and diagnostic testing should be performed on all patients with carbon monoxide poisoning. Abbreviations: NSTEMI: Non-ST elevation myocardial infarction.

Light irradiation for treatment of acute carbon monoxide poisoning: an experimental study

BACKGROUND

Because treatment modalities for carbon monoxide (CO) poisoning, especially normobaric oxygen and hyperbaric oxygen therapies, have limited effects and hyperbaric oxygen is not available at the scene where treatment is most needed, we conducted a study to determine and compare rates of carboxyhemoglobin (COHb) dissociation achieved in human in vitro blood samples under light radiation emitted at three levels of illuminance. This was done with a view toward eventual on-site application.

METHODS

We drew blood from 10 volunteers, prepared 10 red blood cell solutions, and subjected each solution to a CO bubbling procedure to increase the COHb saturation. Samples of each bubbled solution were then divided between 3 beakers (beakers A, B, and C) for a total of 30 beakers. The solution in each beaker was exposed to a continuous flow of oxygen at 50 mL/min, and simultaneously for a period of 15 min, the beaker A and B solutions were irradiated with light emitted at 500,000 and 100,000 lux, respectively, from a halogen light source. The beaker C solutions were exposed to room light. At 3, 6, 9, 12, and 15 min, a 50-μL sample was pipetted from each of the 30 beakers for determination of its light absorbance and the COHb dissociation rate.

RESULTS

Under each of the experimental conditions, dissociation progressed but at different rates, and starting at 3 min, the differences in rates between conditions were significant (P < 0.01). The dissociation rate was greatest with light emitted at 500,000 lux.

CONCLUSIONS

Our results point toward the possibility of readily performed, acute photodissociation therapy for patients with CO poisoning.

Analysis of patients presenting to the emergency department with carbon monoxide intoxication

OBJECTIVES

Carbon monoxide is a potentially fatal form of poisoning. The exact incidence is unclear, due to cases being undiagnosed or reported as fewer than the real number. Hyperbaric oxygen therapy (HBOT) is of proven efficacy in the treatment of CO intoxication. The purpose of this study was to describe the general characteristics of carbon monoxide (CO) intoxications presenting to the emergency department and to investigate troponin I values and the effectiveness of hyperbaric oxygen therapy (HBOT) in these patients.

MATERIAL AND METHODS

Patients presenting to the emergency department with CO intoxication over one year and patients with such intoxications receiving HBOT were examined retrospectively.

RESULTS

One hundred seventy-one patients were included; 140 (81.9%) were poisoned by stoves, 18 (10.5%) by hot water boilers and 10 in (5.8%) by fires. COHb levels were normal in 49 of the 163 patients whose values were investigated, and were elevated in 114 patients. Mean COHb value was 16.6. Troponin I values were investigated in 112 patients. These were normal in 86 patients and elevated in 26. Mean troponin I value was 0.38 ng/ml. One hundred twenty-three of the 171 patients in the study were discharged in a healthy condition after receiving normobaric oxygen therapy, while 48 patients received HBOT. Forty-two (87.5%) of the patients receiving HBOT were discharged in a healthy condition while sequelae persisted in five (10.4%). One patient died after 15 session of HBOT.

CONCLUSION

Although elevated carboxyhemoglobin confirms diagnosis of CO intoxication, normal levels do not exclude it. Troponin I levels may rise in CO intoxication. No significant relation was observed between carboxyhemoglobin and receipt of HBOT. A significant correlation was seen, however, between troponin I levels and receipt of HBOT.

[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.

The neurotoxicology of carbon monoxide - Historical perspective and review

Carbon monoxide (CO) has been recognized as a poison for centuries, and remains one of the most common causes of both accidental and deliberate poisoning worldwide. Despite this, there are widespread misconceptions with regards to the mechanisms, diagnosis and outcomes of CO induced poisoning such as the idea that CO poisoning is rare; that carboxyhaemoglobin levels above 20% and loss of consciousness are required before nervous system damage ensues; and that the binding of CO to haemoglobin is the only mechanism of toxicity. Prevention and diagnosis of CO poisoning is hampered by the lack of awareness of CO as a cause of illness, among both the general public and healthcare professionals. To complicate matters further there is no standardized definition of CO poisoning. Carboxyhaemoglobin levels are often used as a marker of CO poisoning, yet plasma levels rapidly reduce upon removal of the source and are therefore an unreliable biomarker of exposure and tissue damage. Adverse neuropsychiatric outcomes after CO poisoning are difficult to define, especially as they fluctuate, mimic other non-specific complaints, and are not present in all survivors. This paper challenges a number of misconceptions about CO poisoning which can result in misdiagnosis, and consequently in mismanagement. We illustrate how recent developments in the understanding of CO toxicology explain the particular susceptibility of the central nervous system to the effects of CO exposure.

A Randomized Controlled Trial of Puncturing and Bloodletting at Twelve Hand Jing Points to Treat Acute Carbon Monoxide Poisoning as Adjunct to First Aid Treatment: A Study Protocol

Background. Acute carbon monoxide poisoning (ACOP) is a significant cause of morbidity and mortality in many countries. Twelve Hand Jing Points (THJP) have been believed to be effective to treat all kinds of emergency calls in traditional Chinese medicine (TCM) for more than 3000 years. This randomized controlled trial (RCT) is designed to evaluate the effectiveness of THJP in curing acute carbon monoxide poisoning in first aid treatment. This paper reports the protocol of the trial. Methods/Design. This RCT is a multicenter, randomized, controlled study undergoing in China. The compliant patients are divided into the bloodletting group and standard of care group. With first aid treatments given to both of the groups, the bloodletting group is bleeding at THJP upon being hospitalized. Primary outcomes and secondary outcomes will be measured and compared between these two groups. Before treatment, immediately after treatment, and 30 minutes, 1 hour, and 4 hours after treatment, patients' basic vital signs and state of consciousness were observed. Before treatment and 1 and 4 hours after treatment, carboxyhemoglobin concentration in venous blood samples was detected. Discussion. The objective of this study is to provide convincing evidence to clarify the efficacy and safety of THJP for early treatment of acute carbon monoxide poisoning.

Carbon monoxide poisoning increases Tpeak-Tend dispersion and QTc dispersion

Objective

Carbon monoxide (CO) poisoning leads to cardiac dysrhythmia. Increased heterogeneity in ventricular repolarisation on electrocardiogram (ECG) shows an increased risk of arrhythmia. A number of parameters are used to evaluate ventricular repolarisation heterogeneity on ECG. The aim of our study is to investigate the effect of acute CO poisoning on indirect parameters of ventricular repolarisation on ECG.

Methods

Sixty-seven patients were included in this case–control study. Thirty patients with acute CO poisoning were assigned to group 1 (19 females, mean age: 30.8 ± 11.3 years). A control group was formed with patients without known cardiac disease (group 2, n = 37; 25 females, mean age: 26.0 ± 5.2 years). Twelve-lead ECG and serum electrolyte levels were recorded in all patients. Also, carboxyhaemoglobin (COHb) levels were recorded in group 1. T_peak–T_end (T_pT_e) interval, T_pT_e dispersion, T_pT_e/QT ratio, QT interval and QT_d durations were measured as parameters of ventricular repolarisation. Corrected QT (QT_c) and QT_c dispersion (QT_cd) intervals were determined with the Bazett’s formula.

Results

The mean COHb level in group 1 was 27.6 ± 7.4% and mean duration of CO exposure was 163.5 ± 110.9 min. No statistically significant difference was found in age, gender, serum electrolytes or blood pressure levels between the groups. QRS, QT, QT_c, T_pT_e interval and T_pT_e/QT ratio were similar between the groups (p > 0.05). QTcd (65.7 ± 64.4 vs 42.1 ± 14.2 ms, p = 0.003) and T_pT_e dispersion (40.5 ± 14.8 vs 33.2 ± 4.9 ms, p = 0.006) were significantly longer in group 1 than group 2. COHb level was moderately correlated with TpTe dispersion (r = 0.29; p = 0.01).

Conclusion

To our knowledge, this is the first study to investigate T_pT_e interval and dispersion in CO poisoning. Our results showed that T_pT_e dispersion and QTc dispersion increased after CO poisoning.

Assessing inhalation injury in the emergency room

Respiratory tract injuries caused by inhalation of smoke or chemical products are related to significant morbidity and mortality. While many strategies have been built up to manage cutaneous burn injuries, few logical diagnostic strategies for patients with inhalation injuries exist and almost all treatment is supportive. The goals of initial management are to ensure that the airway allows adequate oxygenation and ventilation and to avoid ventilator-induced lung injury and substances that may complicate subsequent care. Intubation should be considered if any of the following signs exist: respiratory distress, stridor, hypoventilation, use of accessory respiratory muscles, blistering or edema of the oropharynx, or deep burns to the face or neck. Any patients suspected to have inhalation injuries should receive a high concentration of supplemental oxygen to quickly reverse hypoxia and to displace carbon monoxide from protein binding sites. Management of carbon monoxide and cyanide exposure in smoke inhalation patients remains controversial. Absolute indications for hyperbaric oxygen therapy do not exist because there is a low correlation between carboxyhemoglobin levels and the severity of the clinical state. A cyanide antidote should be administered when cyanide poisoning is clinically suspected. Although an ideal approach for respiratory support of patients with inhalation injuries do not exist, it is important that they are supported using techniques that do not further exacerbate respiratory failure. A well-organized strategy for patients with inhalation injury is critical to reduce morbidity and mortality.

Salvianolic acids attenuate rat hippocampal injury after acute CO poisoning by improving blood flow properties

Carbon monoxide (CO) poisoning causes the major injury and death due to poisoning worldwide. The most severe damage via CO poisoning is brain injury and mortality. Delayed encephalopathy after acute CO poisoning (DEACMP) occurs in forty percent of the survivors of acute CO exposure. But the pathological cause for DEACMP is not well understood. And the corresponding therapy is not well developed. In order to investigate the effects of salvianolic acid (SA) on brain injury caused by CO exposure from the view point of hemorheology, we employed a rat model and studied the dynamic of blood changes in the hemorheological and coagulative properties over acute CO exposure. Compared with the groups of CO and 20% mannitol + CO treatments, the severe hippocampal injury caused by acute CO exposure was prevented by SA treatment. These protective effects were associated with the retaining level of hematocrit (Hct), plasma viscosity, fibrinogen, whole blood viscosities and malondialdehyde (MDA) levels in red blood cells (RBCs). These results indicated that SA treatment could significantly improve the deformation of erythrocytes and prevent the damage caused by CO poisoning. Meanwhile, hemorheological indexes are good indicators for monitoring the pathological dynamic after acute CO poisoning.