Waterpipe vs non-Waterpipe carbon monoxide poisoning: Comparison of patient characteristics, clinical presentation and outcomes.

OBJECTIVE: The aim of this study is to describe the difference between carboxyhemoglobin (CO-Hb) acute poisoning caused by waterpipe vs non-waterpipe exposures as they relate to demographics, clinical presentations and outcome of patients. DESIGN: Retrospective cohort study conducted in the Emergency Department (ED) at the Lebanon. PATIENTS: All adult patients presenting with a CO-Hb level ≥ 10 between January 2019 and August 2023 with exposure types stratified as waterpipe or non-waterpipe. MEASUREMENTS AND MAIN RESULTS: 111 ED visits were identified. Among these, 73.9% were attributed to waterpipe exposure, while 26.1% were non-waterpipe sources. These included cigarette smoking (17.2%), burning coal (24.1%), fire incidents (3.6%), gas leaks (6.9%), heating device use (10.3%), and undocumented sources (37.9%). Patients with waterpipe-related carbon monoxide exposure were younger (41 vs 50 years, p = 0.015) women (63.4 vs 41.4%, p = 0.039) with less comorbidities compared to non-waterpipe exposures (22.2 vs 41.4%, p = 0.047). Waterpipe smokers were more likely to present during the summer (42.7 vs 13.8%, p = 0.002) and have shorter ED length of stays (3.9 vs 4.5 h, p = 0.03). A higher percentage of waterpipe smokers presented with syncope (52.4 vs 17.2%, p = 0.001) whereas cough/dyspnea were more common in non-waterpipe exposures (31 vs 9.8%, p = 0.006). The initial CO-Hb level was found to be significantly higher in waterpipe exposure as compared to non-waterpipe (19.7 vs 13.7, p = 0.004). Non-waterpipe exposures were more likely to be admitted to the hospital (24.1 vs 4.9%, p = 0.015). Waterpipe smokers had significantly higher odds of experiencing syncope, with a 5.74-fold increase in risk compared to those exposed to non-waterpipe sources (p = 0.004) irrespective of their CO-Hb level. Furthermore, males had significantly lower odds of syncope as compared to females, following carbon monoxide exposure (aOR 0.31, 95% CI 0.13-0.74). CONCLUSION: CO-Hb poisoning related to waterpipe smoking has distinctive features. Syncope is a commonly associated presentation that should solicit a focused social history in communities where waterpipe smoking is common. Furthermore, CO-Hb poisoning should remain on the differential in patients presenting with headache, syncope, dizziness, vomiting or shortness of breath, even outside of the non-waterpipe exposure peaks of winter season.

From suicide to accident - Case report - The significance of the medico-legal autopsies.

INTRODUCTION: Suicide is the intentional and voluntary act of destroying one's own life, while an accident is an unintended event that involuntarily causes injury to one's health or destruction of life. CASE PRESENTATION: We report a case of a 54-year-old male who was found in a forest in late November, approximately 500 m away from his car. He was positioned bent over a trunk of a tree with his head beneath the rest of his body. His pants were down to his knees, and there were soiled blades of grass and leaves on his body. Investigation of the case circumstances revealed that he had attempted suicide by carbon monoxide poisoning, using a hose connected to the exhaust pipe and running it through the window into the cabin. Window on the driver's side was broken with glass particles on the driver's seat. Wrappers from "Rivotril" tablets, a generic benzodiazepine, were also found in the car. Autopsy revealed the following: postmortem hypostasis was of a cherry red color and well pronounced on the upper part of the front of the body and face. Numerous bruises, contusions, and erosions were present all over the body. Frostbites were especially pronounced in the knees and elbows area. The synovial membranes were partially bloodstained and reddish in color. Opening the stomach revealed erosions of the gastric mucosa (Wischnewsky sign). Chemical toxicological analysis detected presence of benzodiazepines and carboxyhemoglobin (25%). CONCLUSION: Based on the autopsy findings, chemical toxicological analyses, and investigation of the case circumstances, it has been concluded that the death occurred due to the combined effects of hypothermia, postural asphyxia and carboxyhemoglobin and benzodiazepine intoxication. The manner of death in this case is a combination of accidental and suicidal, as the victim attempted suicide but ultimately died due to exposure to low external temperature.

Duplicate measures of hemoglobin mass within an hour: feasibility, reliability, and comparison of three devices in supine position.

Duplicate measure of hemoglobin mass by carbon monoxide (CO)-rebreathing is a logistical challenge as recommendations prompt several hours between measures to minimize CO-accumulation. This study investigated the feasibility and reliability of performing duplicate CO-rebreathing procedures immediately following one another. Additionally, it was evaluated whether the obtained hemoglobin mass from three different CO-rebreathing devices is comparable. Fifty-five healthy participants (22 males, 23 females) performed 222 duplicate CO-rebreathing procedures in total. Additionally, in a randomized cross-over design 10 participants completed three experimental trials, each including three CO-rebreathing procedures, with the first and second separated by 24 h and the second and third separated by 5-10 min. Each trial was separated by >48 h and conducted using either a glass-spirometer, a semi-automated electromechanical device, or a standard three-way plastic valve designed for pulmonary measurements. Hemoglobin mass was 3 ± 22 g lower (p < 0.05) at the second measure when performed immediately after the first with a typical error of 1.1%. Carboxyhemoglobin levels reached 10.9 ± 1.3%. In the randomized trial, hemoglobin mass was similar between the glass-spirometer and three-way valve, but ∼6% (∼50 g) higher for the semi-automated device. Notably, differences in hemoglobin mass were up to ∼13% (∼100 g) when device-specific recommendations for correction of CO loss to myoglobin and exhalation was followed. In conclusion, it is feasible and reliable to perform two immediate CO-rebreathing procedures. Hemoglobin mass is comparable between the glass-spirometer and the three-way plastic valve, but higher for the semi-automated device. The differences are amplified if the device-specific recommendations of CO-loss corrections are followed.

Elevated methemoglobin levels in patients treated with high-dose hydroxocobalamin.

OBJECTIVE: The aim of this study was to assess the impact of hydroxocobalamin (OHCbl) infusion on arterial blood gas and oximetry values in patients with vasoplegic syndrome. METHODS: Blood samples collected from 95 patients receiving OHCbl infusion were assayed using the ABL90 FLEX Plus blood gas analyzer for the concentration of methemoglobin (MetHb), total hemoglobin (tHb), carboxyhemoglobin (COHb), arterial oxygen saturation (SaO2), arterial oxygen partial pressure (PaO2), and arterial carbon dioxide partial pressure (PaCO2). Interference of OHCbl on these variables was evaluated using the measured difference between the preinfusion and postinfusion samples. RESULTS: Blood MetHb (%) measured after the infusion of OHCbl (5g) were significantly higher than the baseline levels, with a median of 4.8 (IQR, 3.0-6.5) versus 1.0 (IQR, 1.0-1.2) (P < .001). Blood COHb (%) increased from a median of 1.3 (IQR, 1.0-1.8) to 1.7 (IQR, 1.3-2.2) (P < .001) following the OHCbl infusion. No differences were seen in median levels of tHb, PaO2, PaCO2, and SaO2 between pre- and post-OHCbl treatment. CONCLUSION: The presence of OHCbl in blood clearly interfered with the oximetry measurements of the hemoglobin component fractions by falsely increasing the levels of MetHb and COHb. Blood levels of MetHb and COHb cannot be reliably determined by the co-oximetry when OHCbl is known or suspected.

Carbon monoxide poisoning cases in the emergency department are increasing in the last decade in Jerusalem.

BACKGROUND AND AIMS: The aim of our study was to describe the epidemiology of Carbon monoxide poisoning in the Emergency Department. METHODS: A retrospective descriptive analysis of patients with Carbon monoxide poisoning who were presented to the Emergency Department of Hadassah hospital in Jerusalem from 2007 to 2016. All patients that were included are confirmed cases [carboxyhemoglobin level > 5%]. Sources of exposure, seasonal variation, and demographic characteristics were analyzed. RESULTS: There were 244 patients (60% males) with 37 family clusters that accounted for 135 (55.3%) patients. One hundred seventy-three (70.9%) patients presented during the winter months. The main sources of exposure were: non-gas residential heating system, mainly charcoal grills and kerosene stoves (n = 100, 41%). Other sources were fires (n = 70, 28.7%), faulty gas heater (n = 34, 13.9%) and smoking (n = 15, 6.1%). The estimated annual incidence increased from an average of 20.8 cases a year between 2007-2011 to an average of 34 cases in 2011-2016. High-risk poisoning (levels > 25%) occurred in 28 patients (11.5%). Factors associated with severe poisoning were female gender and exposure in clusters compared with individual patients. CONCLUSION: Our current study has showed an increase of Carbon Monoxide poisoning in contrary to our study performed in the previous decade. Fortunately, we did find a lower rate of cases with severe poisoning. Beside the implementation of safer standards for residential heating systems, customized public education is advised in order to lower rates of poisoning in the future. A predicted heavy snow fall should be considered a trigger for a public health warning regarding the risk of CO poisoning.

Carboxyhemoglobin and Methemoglobin Levels and Hemolysis in Children Undergoing Cardiac Surgery With Cardiopulmonary Bypass.

Hemolysis is a complication of cardiopulmonary bypass (CPB). Carboxyhemoglobin (COHb) and methemoglobin (MetHb) were suggested as potential hemolysis biomarkers. This retrospective study was based on a prospective registry aimed to determine the association of COHb and MetHb levels with hemolysis in pediatric patients <4 years old who underwent cardiac surgery with CPB. Plasma-free hemoglobin (PFH), COHb, and MetHb levels were measured before CPB; every 30 minutes during CPB; and on postoperative days 1, 2, and 3. Patients were classified into hemolysis and nonhemolysis groups based on the maximum PFH levels during CPB. A total of 193 patients were included. No significant difference was observed in the maximum COHb levels during CPB (COHb CPB ) between the hemolysis and nonhemolysis groups (1.2% [interquartile range {IQR} 0.9-1.4%] vs. 1.1% [IQR: 0.9-1.4%]; p = 0.17). The maximum MetHb levels during CPB (MetHb CPB ) were significantly higher in the hemolysis group than in the nonhemolysis group (1.3% [IQR: 1.1-1.5%] vs. 1.2% [IQR: 1.0-1.4%]; p = 0.007). Areas under the receiver operating curves of COHb CPB and MetHb CPB were 0.557 (95% confidence interval: 0.475-0.640) and 0.615 (95% confidence interval: 0.535-0.695), respectively. Therefore, the predictive ability of both hemolysis biomarkers during CPB is limited.

Exposure levels for carbon monoxide in nuclear submarine atmosphere.

This work proposes exposure limits for carbon monoxide in the nuclear submarine environment. Linear and non-linear forms of the Coburn-Foster-Kane equation were used to evaluate carbon monoxide exposure for an environment with low oxygen content, different exposure times and crew physical activity levels. We evaluated the 90-day Continuous Exposure Guidance Level, 24-h and 1-h Emergency Exposure Guidance Levels and 10-day and 24-h Submarine Escape Action Levels. The results showed that the concentration of carbon monoxide in the environment must not exceed 9 ppm for the 90-day Continuous Exposure Guidance Level, 35 ppm for the 24-h Emergency Exposure Guidance Level, 90 ppm 1-h Emergency Exposure Guidance Level, 60 ppm for the 10-day Submarine Escape Action Level and 80 ppm for the 24-h Submarine Escape Action Level. Comparing these values with those established by the National Research Council for the United States Navy, the limits proposed by this work are verified to be lower, which may indicate a risk to the health of the crew. They also show the impact of the crew's level of physical activity on the formation of carboxyhemoglobin.

Evolution of Carboxyhemoglobin in Children Supported by Extracorporeal Membrane Oxygenation: An Observational Single-Center Study.

Carboxyhemoglobin (COHb) is potentially a novel marker of hemolysis on extracorporeal membrane oxygenation (ECMO) and may be useful as an indicator for circuit-related complication in adults, but little is known about COHb levels in children. An observational single-center study was performed between January 2018 and December 2021. Fifty-eight children were included and COHb levels were obtained along with routine blood gas analysis before, during, and after ECMO support. From the 6th hour of ECMO support, the COHb level increased relative to the pre-ECMO level, with an adjusted mean difference of 0.44 (95% confidence interval [CI], 0.26-0.62; p < 0.001) and remained higher during ECMO run and within 6 hours after weaning ( p < 0.001). Among the 18 children (31%) who experienced at least one circuit-related complication leading to a circuit change, we observed a significant decrease in COHb levels within 24 hours after the circuit change, compared with the 24 hours before (adjusted mean difference, 0.54%; 95% CI, 0.27-0.80; p < 0.001). The maximal daily COHb level was able to predict circuit-related complications within 24 hours following COHb measurement with an area under the receiver operating characteristic (ROC) curve of 0.85 (95% CI, 0.77-0.92; p < 0.001).

The Critical Assessment of Oxidative Stress Parameters as Potential Biomarkers of Carbon Monoxide Poisoning.

In conventional clinical toxicology practice, the blood level of carboxyhemoglobin is a biomarker of carbon monoxide (CO) poisoning but does not correspond to the complete clinical picture and the severity of the poisoning. Taking into account articles suggesting the relationship between oxidative stress parameters and CO poisoning, it seems reasonable to consider this topic more broadly, including experimental biochemical data (oxidative stress parameters) and patients poisoned with CO. This article aimed to critically assess oxidative-stress-related parameters as potential biomarkers to evaluate the severity of CO poisoning and their possible role in the decision to treat. The critically set parameters were antioxidative, including catalase, 2,2-diphenyl-1-picryl-hydrazyl, glutathione, thiol and carbonyl groups. Our preliminary studies involved patients (n = 82) admitted to the Toxicology Clinical Department of the University Hospital of Jagiellonian University Medical College (Kraków, Poland) during 2015-2020. The poisoning was diagnosed based on medical history, clinical symptoms, and carboxyhemoglobin blood level. Blood samples for carboxyhemoglobin and antioxidative parameters were collected immediately after admission to the emergency department. To evaluate the severity of the poisoning, the Pach scale was applied. The final analysis included a significant decrease in catalase activity and a reduction in glutathione level in all poisoned patients based on the severity of the Pach scale: I°-III° compared to the control group. It follows from the experimental data that the poisoned patients had a significant increase in level due to thiol groups and the 2,2-diphenyl-1-picryl-hydrazyl radical, with no significant differences according to the severity of poisoning. The catalase-to-glutathione and thiol-to-glutathione ratios showed the most important differences between the poisoned patients and the control group, with a significant increase in the poisoned group. The ratios did not differentiate the severity of the poisoning. The carbonyl level was highest in the control group compared to the poisoned group but was not statistically significant. Our critical assessment shows that using oxidative-stress-related parameters to evaluate the severity of CO poisoning, the outcome, and treatment options is challenging.

Thoracic cavity fluid as an alternative specimen for carboxyhaemoglobin measurement in post-mortem toxicology.

Post-mortem blood is most frequently used for the measurement of carboxyhaemoglobin (COHb) in post-mortem forensic cases, when investigating suspected inhalation of carbon monoxide (CO). However, in many post-mortem cases (especially severe burns and charring deaths), adequate blood specimens are not always available for toxicological analyses. Here, the availability of an alternative specimen for COHb analysis is required. This study investigated the suitability of thoracic cavity fluid (TCF) as an alternative specimen for the measurement of COHb. TCF and comparative blood samples from fifteen potential CO toxicity cases were collected into green-top tubes (containing lithium heparin) and analysed immediately after collection using a validated method on the ABL825 FLEX Radiometer CO-oximeter. Pearson's correlation coefficient indicated a strong positive relationship between the two specimens (r = 0.975, n = 10, p < 0.001). A statistical agreement between COHb concentrations from blood and TCF was demonstrated using the Bland-Altman plot, with a slight bias of 1.54 % when blood was taken as the standard. This study found that TCF would be a suitable alternative to blood for the measurement of COHb using the ABL825 FLEX blood gas analyser.

El rol del laboratorio en los hallazgos de intoxicación y exposición a monóxido de carbono / The role of the laboratory in findings of carbon monoxide poisoning and exposure

El monóxido de carbono es un gas altamente tóxico que se origina principalmente por la combustión incompleta de combustibles fósiles. La intoxicación presenta síntomas inespecíficos que solapan otras patologías y por lo tanto es indispensable la confirmación mediante la medición de la carboxihemoglobina en sangre. El laboratorio incorporó la determinación en el informe del estado ácido base a partir de octubre del 2018, debido a que previamente el médico debía solicitarla frente a la sospecha de una intoxicación. El objetivo del trabajo fue evaluar si esta medida implementada por el laboratorio contribuyó a mejorar el diagnóstico de intoxicación por CO, analizar las características de los pacientes con COHb mayor o igual a 5% y definir un valor de reporte inmediato para la COHb. El 46% de los casos con COHb mayor o igual a 5% no se relacionaban con una intoxicación y/o exposición a CO. De los casos de intoxicación se encontró que el 77% fueron diagnosticados a partir de la sospecha médica y un 23% por hallazgo del laboratorio. Se concluyó que es de mucha utilidad el rol del laboratorio en detectar aquellos casos que no fueron evidentes clínicamente. Existen ciertas patologías como las oncológicas o la enfermedad de Wilson donde se vieron valores elevados de COHb sin presentar intoxicación y se definió finalmente, como valor de reporte inmediato 7% para la COHb. (AU)

Carbon monoxide is a highly toxic gas that originates mainly from incomplete combustion of fossil fuels. Intoxication causes nonspecific symptoms that overlap with other conditions and, therefore, confirmation by measuring blood carboxyhemoglobin is essential. The laboratory incorporated the measurement in the acid-base status report as of October 2018, as it was previously required to be requested by the physician in case of suspected intoxication. The aim of this study was to evaluate whether this measure implemented by the laboratory contributed to the improvement of the diagnosis of CO intoxication, to analyze the characteristics of patients with COHb greater than or equal to 5% and to define an immediate reporting value for COHb. Overall, 46% of the cases with COHb greater than or equal to 5% were not related to CO poisoning and/or exposure. Of the cases of intoxication, 77% were diagnosed based on medical suspicion and 23% on laboratory findings. It was concluded that the laboratory has a useful role in detecting cases that were not clinically evident. There are certain diseases including different types of cancer or Wilson's disease where elevated COHb values were seen without intoxication and finally, 7% for COHb was defined as the immediate reporting value (AU)

Use of CO-oximetry to confirm carboxyhemoglobinemia in cats involved in secondary arson homicide.

The body of a deceased human and 4 deceased cats were found in a house while a fire was being extinguished. As a result of these findings, arson, homicide, and animal death investigations were opened. As part of the animal death investigation, all of the cats were submitted for veterinary forensic autopsies. All cats had soot on the fur and had soot deposits within the oral cavity, esophagus, and respiratory tract. Two cats had soot within the stomach. Cardiac blood was analyzed for carboxyhemoglobin using a CO-oximeter, and all cats had levels >65%. The cause of death was determined to be due to toxic smoke inhalation from the structure fire. Case findings support the potential use of CO-oximeter for determination of carboxyhemoglobin levels in cats and continued research in this area of forensic practice.

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

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

Carbon monoxide as a clinical marker of hemolysis.

Carbon monoxide (CO)-based tests have precisely measured hemolysis for over 40 years. End-tidal CO was the primary marker in clinical hematology research, followed by carboxyhemoglobin. Quantification of CO reflects heme oxygenases degrading heme in a 1:1 stoichiometric ratio, making CO a direct marker of hemolysis. CO in alveolar air can be quantified using gas chromatography, whose high resolution allows detecting mild and moderate levels of hemolysis. CO can be elevated in active bleeding, resorbing hematoma, and smoking. Clinical acumen and other markers remain necessary to diagnose the cause of hemolysis. CO-based tests constitute an opportunity for bench-to-bedside technology transfer.

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

BACKGROUND AND OBJECTIVES: Approximately 50,000 emergency department visits per year due to carbon monoxide (CO) poisoning occur in the United States alone. Tissue hypoxia can occur at very low CO concentration exposures because CO binds with a 250-fold higher affinity than oxygen to hemoglobin. The most effective therapy is 100% hyperbaric oxygen (HBO) respiration. However, there are only a limited number of cases with ready accessibility to the specialized HBO chambers. In previous studies, we developed an extracorporeal veno-venous membrane oxygenator that facilitates exposure of blood to an external visible light source to photo-dissociate carboxyhemoglobin (COHb) and significantly increase CO removal from CO-poisoned blood (photo-extracorporeal veno-venous membrane oxygenator [p-ECMO]). One objective of this study was to describe in vitro experiments with different laser wavelength sources to compare CO elimination rates in a small unit-cell ECMO device integrated with a light-diffusing optical fiber. A second objective was to develop a mathematical model that predicts CO elimination rates in the unit-cell p-ECMO  device design upon which larger devices can be based. STUDY DESIGN/MATERIAL AND METHODS: Two small unit-cell p-ECMO devices consisted of a plastic capillary with a length and inside diameter of 10 cm and 1.15 mm, respectively. Either five (4-1 device) or seven (6-1 device) gas exchange tubes were placed in the plastic capillary and a light-diffusing fiber was inserted into one of the gas exchange tubes. Light from lasers emitting either 635 nm or 465 nm wavelengths was coupled into the light-diffusing fiber as oxygen flowed through the gas exchange membranes. To assess the ability of the device to remove CO from blood in vitro, the percent COHb reduction in a single pass through the device was assessed with and without light. The Navier Stokes equations, Carreau-Yesuda model, Boltzman equation for light distribution, and hemoglobin kinetic rate equations, including photo-dissociation, were combined in a mathematical model to predict COHb elimination in the experiments. RESULTS: For the unit-cell devices, the COHb removal rate increases with increased 635 nm laser power, increased blood time in the device, and greater gas exchange membrane surface-to-blood volume ratio. The 6-1 device COHb half-life versus that of the 4-1 device with 4 W at 635 nm light was 1.5 min versus 4.25 min, respectively. At 1 W laser power, 635 nm and 465 nm exhibited similar CO removal rates. The COHb half-life times of the 6-1 device were 1.25, 2.67, and 8.5 min at 635 nm (4 W), 465 nm (1 W), and 100% oxygen only, respectively. The mathematical model predicted the experimental results. An analysis of the in vivo COHb half-life of oxygen respiration therapy versus an adjunct therapy with a p-ECMO device and oxygen respiration shows a reduction from 90 min to as low as 10 min, depending on the device design. CONCLUSION: In this study, we experimentally studied and developed a mathematical model of a small unit-cell ECMO device integrated with a light-diffusing fiber illuminated with laser light. The unit-cell device forms the basis for a larger device and, in an adjunct therapy with oxygen respiration, has the potential to remove COHb at much higher rates than oxygen therapy alone. The mathematical model can be used to optimize the design in practical implementations to quickly and efficiently remove CO from CO-poisoned blood.

Impact of storage temperature and time before analysis on electrolytes (Na+, K+, Ca2+), lactate, glucose, blood gases (pH, pO2, pCO2), tHb, O2Hb, COHb and MetHb results.

OBJECTIVES: The objective of our study is to evaluate the effect of storage temperature and time to analysis on arterial blood gas parameters in order to extend the CLSI recommendations. METHODS: Stability of 12 parameters (pH, pCO2, pO2, Na+, K+, Ca2+, glucose, lactate, hemoglobin, oxyhemoglobin, carboxyhemoglobin, methemoglobin) measured by GEM PREMIER™ 5000 blood gas analyzer was studied at room temperature and at +4 °C (52 patients). The storage times were 30, 45, 60, 90 and 120 min. Stability was evaluated on the difference from baseline, the difference from the analyte-specific measurement uncertainty applied to the baseline value, and the impact of the variation on the clinical interpretation. RESULTS: At room temperature, all parameters except the lactate remained stable for at least 60 min. A statistically significant difference was observed for pH at T45 and T60 and for pCO2 at T60 without modification of clinical interpretation. For lactate, clinical interpretation was modified from T45 and values were outside the range of acceptability defined by the measurement uncertainty. All parameters except pO2 remained stable for at least 120 min at +4 °C. CONCLUSIONS: A one-hour transport at room temperature is compatible with the performance of all the analyses studied except lactate. If the delay exceeds 30 min, the sample should be placed at +4 °C for lactate measurement. If the samples are stored in ice, it is important to note that the pO2 cannot be interpreted.

Clinical and Laboratory Characteristics Predicting the Severity of Carbon Monoxide Poisoning in Children: A Single-Center Retrospective Study.

OBJECTIVES: Carbon monoxide poisoning (COP) is extremely common throughout the world. The purpose of this study was to assess the demographic, clinical, and laboratory characteristics predicting the severity COP in children. METHODS: The study included 380 children diagnosed with COP between January 2017 and January 2021 and 380 healthy controls. Carbon monoxide poisoning was diagnosed based on the medical history and a carboxyhemoglobin (COHb) level of more than 5%. The patients were classified as mild (COHb 10%), moderate (COHb 10%-25%), or severely (COHb > 25%) poisoned. RESULTS: The mean age of the severe group was 8.60 ± 6.30, for the moderate group was 9.50 ± 5.81, for the mild group was 8.79 ± 5.94, and for the control group was 8.95 ± 5.98. The most common place of exposure was at home and all cases were affected accidentally. The coal stove was the most common source of exposure, followed by natural gas. The most common symptoms were nausea/vomiting, vertigo, and headache. Neurologic symptoms such as syncope, confusion, dyspnea, and seizures were more common in the severe group. A total of 91.3% of the children had hyperbaric oxygen therapy, 3.8% were intubated, and 3.8% were transferred to intensive care in the severe group, whereas no death or sequela was observed. Mean platelet volume and red cell distribution width had the highest area under the curve in the receiver operating characteristic analysis (0.659; 0.379). A positive and low statistically significant relationship was found between COHb levels and troponin and lactate levels in the severe group ( P < 0.05). CONCLUSIONS: Carbon monoxide poisoning progressed more severely in children presented with neurological symptoms and have elevated red cell distribution width and mean platelet volume. Even in severe COP cases, satisfactory results have been obtained with early and appropriate treatment.

Analyses of physical factors that contribute to the blood carboxyhemoglobin saturation in autopsy cases of house fire fatalities.

The authors analyzed data from forensic autopsies of 75 patients who died as a result of house fires to clarify the physical factors that affect blood carboxyhemoglobin (COHb) saturation. Blood COHb saturation levels were significantly lower in patients who survived in the hospital. No significant differences were found in the blood COHb saturation levels between patients who died immediately at the scene and those who were pronounced dead at the receiving hospital without heartbeat being restored. The COHb saturation levels were significantly different among the groups of patients classified by the amount of soot. Although age, coronary artery stenosis, and blood alcohol concentration did not significantly affect blood COHb saturation, on comparing patients who died in the same fire, lower COHb saturation was observed in two patients, one with severe coronary artery stenosis and other with severe alcohol intoxication. To accurately interpret blood COHb saturation during forensic autopsy, the heartbeat status (present or absent) at the time of the rescue and the amount of soot in the trachea must be determined. Low levels of COHb saturation may be observed in fatalities with severe coronary atherosclerosis or severe alcohol intoxication.

Burn index, burn characteristics and carboxyhemoglobin levels in indoor fire-related deaths: Significance and interpretation of the autopsy findings.

INTRODUCTION: The Burn Index (BI) is a significant clinical prognostic parameter for patients with burns. It simultaneously considers major mortality risk factors: age and burns extensivity. Despite the inability to distinguish between ante- and post-mortem burns, their characteristics on autopsy might indicate if a significant thermal injury occurred before the onset of death. We investigated whether autopsy BI, burn extensivity, and severity could tell whether burns were the concurrent cause of fire-related death (FRD), even if the body remained in a fire. MATERIAL AND METHODS: Ten-year retrospective study analyzed FRD that occurred at the scene in a confined space. Soot aspiration was the main inclusion criterion. Autopsy reports were reviewed for demographic data, burn characteristics (degree, Total Body Surface Area burned- TBSA), coronary artery disease, and blood ethanol. We calculated the BI as a sum of the victim's age and percentage of TBSA affected by 2nd, 3rd and 4th-degree burns. Cases were divided into two groups: those with COHb≤ 30% and with COHb> 30%. Subjects with burned TBSA≤ 40% were analyzed separately afterward. RESULTS: The study included 53 males (71.6%) and 21 females (28.4%). No significant difference in age was observed between groups (p > 0.05). COHb≤ 30% had 33, and COHb> 30% had 41 victims. BI and burns extensivity (TBSA) had significant negative correlation with COHb values (ρ = -0.581, p < 0.01 and ρ = -0.439, p < 0.01, respectively). Both were significantly higher in subjects with COHb≤ 30% compared to those with COHb> 30% (140.7 ± 29.57 vs. 95.49 ± 38.49, p < 0.01 and 98 (13-100) vs. 30 (0-100), p < 0.01, BI and TBSA respectively). BI had excellent and TBSA fair performance for detection of subjects with COHb≤ 30% on ROC curve analysis (AUCs 0.821, p < 0.001 and 0.765, p < 0.001), with optimal cut-off values: BI≥ 107 (sensitivity 81.3%, specificity 70.7%) and TBSA≥ 45 (sensitivity 84.8%, specificity 70.7%). On logistic regression analysis BI≥ 107 was independently associated with COHb≤ 30% values (aOR 6; 95%CI 1.55-23.37). The same holds for the presence of 3rd-degree burns (aOR 5.9; 95%CI 1.45-23.99). In the subgroup of subjects with TBSA≤ 40% burned, those with COHb≤ 50% were significantly older than victims with COHb> 50% (p < 0.05). Here BI≥ 85 was a particularly good predictor for detection of subjects with COHb≤ 50% (AUC=0.913, p < 0.001, 95% CI 0.813-1.00; sensitivity 90.9%, specificity 81%). CONCLUSION: The BI≥ 107, TBSA≥ 45% burned, and 3rd-degree burns observed on autopsy point to a significantly higher odds that limited CO intoxication occurred, and burns should be considered a concurrent cause of indoor FRD. When less than 40% of TBSA was affected, BI≥ 85 indicated sub-lethal CO poisoning.

Intoxicación por monóxido de carbono: estudio observacional de pacientes que acudieron a Urgencias durante 2020 / Carbon monoxide poisoning: an observational study of patients admitted to Emergency Department during 2020

El objetivo fue describir las intoxicaciones monóxido de carbono. Se diseñó un corte transversal que incluyó una muestra consecutiva de mediciones de carboxihemoglobina (COHb), realizadas Enero y Diciembre 2020 en la Central de Emergencias del Hospital Italiano de Buenos Aires. Se utilizaron bases secundarias y revisión manual de historias clínicas para recolección de varia-bles de interés. Durante el período de estudio hubo 20 pacientes confirmados, con media de 50 años (DE 20), 55% sexo masculino, 20% tabaquistas, y una única embarazada. El 70% correspondieron al trimestre Junio-Julio-Agosto. La fuente de intoxicación más frecuente se debió a accidentes domésticos (calefón, estufa, brasero, hornalla, salamandra) que representaron el 50% de los casos, 30% por incendios, y el 20% restante explicado por tabaco o factor desconocido. Los estudios de laboratorio más solicitados fueron: 95% recuento de glóbulos blancos, 85% glucemia, 70% CPK, y 55% troponina. Los hallazgos relevantes fueron COHb con mediana de 7.15%, CPK con mediana de 89 U/mL, y troponina con mediana de 8.5 pg/mL. La totalidad se realizó electrocardiograma: 15% presentaron arritmia como hallazgo patológico, y ninguno isquemia. En cuanto la presentación clínica: 30% presentó cefalea, 15% síncope, 15% coma, 10% mareos y 10% convulsiones. Sólo 25% tuvieron tomografía y 15% resonancia de cerebro, sin hallazgos críticos. Sin embargo, 15% fueron derivados para trata-miento con cámara hiperbárica. La mayoría ocurrieron en invierno y explicados por accidentes domésticos. Será necesario un fortalecimiento del rol preventivo que apunte al control de la instalación y el buen funcionamiento de artefactos, como mantener los ambientes bien ventilados (AU)

The objective was to describe carbon monoxide poisoning. A cross sectional was designed, which included a consecutive sample of carboxyhemoglobin (COHb) measurements, carried from January to December 2020 at the Emergency Department of tHospital Italiano de Buenos Aires. Secondary databases and manual review of medical records were used to collect variables of interest. During the study period there were 20 confirmed patients, with a mean age of 50 (SD 20), mostly male (55%), 20% smokers, and only one pregnant woman, 70% corresponded to June-July-August. The most frequent source of poisoning was explained to domestic accidents (water heater, stove, brazier, stove, salamander) which represented 50% of cases, 30% due to fires, and the remaining 20% by tobacco or unknown factor. The most laboratory studies were: 95% white blood cell count, 85% glycemia, 70% CPK, and 55% troponin. Meanwhile, relevant findings were carboxyhemoglobin with a median of 7.15%, CPK with a median of 89 U/mL, and troponin with a median of 8.5 pg/mL. All underwent an electrocardiogram: 15% presented arrhythmia as a pathological finding, and none ischemia. Regarding the clinical presentation: 30% presented headache, 15% syncope, 15% coma, 10% dizziness and 10% seizures. Only 25% had brain tomography and 15% MRI, without pathological findings. However, 15% were referred for treatment with a hyperbaric chamber. Most of the cases occurred in winter and explained by domestic accidents. It will be necessary to strengthen the preventive role that aims to control the installation and the proper functioning of devices, such as keeping rooms well ventilated (AU)