Measurement Of Carboxyhemoglobin Research Articles

Carboxyhemoglobin predicts oxygenator performance and imminent oxygenator change in extracorporeal membrane oxygenation

BackgroundThe continuous exposure of blood to a non-biological surface during extracorporeal membrane oxygenation (ECMO) may lead to progressive thrombus formation in the oxygenator, hemolysis and consequently impaired gas exchange. In most centers oxygenator performance is monitored only on a once daily basis. Carboxyhemoglobin (COHb) is generated upon red cell lysis and is routinely measured with any co-oximetry performed to surveille gas exchange and acid–base homeostasis every couple of hours. This retrospective cohort study aims to evaluate COHb in the arterial blood gas as a novel marker of oxygenator dysfunction and its predictive value for imminent oxygenator change.ResultsOut of the 484 screened patients on ECMO 89, cumulatively requiring 116 oxygenator changes within 1833 patient days, including 19,692 arterial COHb measurements were analyzed. Higher COHb levels were associated with lower post-oxygenator pO2 (estimate for log(COHb): − 2.176 [95% CI − 2.927, − 1.427], p < 0.0001) and with a shorter time to oxygenator change (estimate for log(COHb): − 67.895 [95% CI − 74.209, − 61.542] hours, p < 0.0001). COHb was predictive of oxygenator change within 6 h (estimate for log(COHb): 5.027 [95% CI 1.670, 15.126], p = 0.004).ConclusionCOHb correlates with oxygenator performance and can be predictive of imminent oxygenator change. Therefore, longitudinal measurements of COHb in clinical routine might be a cheap and more granular candidate for ECMO surveillance that should be further analyzed in a controlled prospective trial design.

Carboxyhemoglobin in Cardiac Surgery Patients and Its Association with Risk Factors and Biomarkers of Hemolysis.

Cardiac surgery with cardiopulmonary bypass (CPB) is associated with hemolysis. Yet, there is no easily available and frequently measured marker to monitor this hemolysis. However, carboxyhemoglobin (CO-Hb), formed by the binding of carbon monoxide (a product of heme breakdown) to hemoglobin, may reflect such hemolysis. We hypothesized that CO-Hb might increase after cardiac surgery and show associations with operative risk factors and indirect markers for hemolysis. We conducted a retrospective descriptive cohort study of data from on-pump cardiac surgery patients. We analyzed temporal changes in CO-Hb levels and applied a generalized linear model to assess patient characteristics associated with peak CO-Hb levels. Additionally, we examined their relationship with red blood cell (RBC) transfusion and bilirubin levels. We studied 38,487 CO-Hb measurements in 1735 patients. CO-Hb levels increased significantly after cardiac surgery, reaching a peak CO-Hb level 2.1 times higher than baseline ( P < .001) at a median of 17 hours after the initiation of surgery. Several factors were independently associated with higher peak CO-Hb, including age ( P < .001), preoperative respiratory disease ( P = .001), New York Heart Association Class IV ( P = .019), the number of packed RBC transfused ( P < .001), and the duration of CPB ( P = .002). Peak CO-Hb levels also significantly correlated with postoperative total bilirubin levels (Rho = 0.27, P < .001). CO-Hb may represent a readily obtainable and frequently measured biomarker that has a moderate association with known biomarkers of and risk factors for hemolysis in on-pump cardiac surgery patients. These findings have potential clinical implications and warrant further investigation.

Chronic household air pollution and exposure patterns among Himalayan nomads

BackgroundHousehold air pollution (HAP) is a major risk factor of non-communicable diseases, causing millions of premature deaths each year in developing nations. Populations living at high altitudes are particularly vulnerable to HAP and associated health outcomes.ObjectivesThis study aims to explore the relationships between activity patterns, HAP, and an HAP biomarker among 100 Himalayan nomadic households during both cooking and heating-only periods.MethodsHousehold CO was monitored in 100 rural homes in Qinghai, China, at 3500 m on the Himalayan Plateau among Himalayan nomads. Carboxyhemoglobin (COHb) was used as a biomarker to assess exposure among 100 male and 100 female heads of household. Linear mixed-effects models were used to explore the relationship between COHb and activity patterns.ResultsCooking periods were associated with 7 times higher household CO concentrations compared with heating periods (94 ± 56 ppm and 13 ± 11 ppm, respectively). Over the three-day biomarker-monitoring period in each house, 99% of subjects had at least one COHb measurement exceeding the WHO safety level of 2%. Cooking was associated with a 32% increase in COHb (p < 0.001).Impact statementThis study on household air pollution (HAP) in high-altitude regions provides important insights into the exposure patterns of nomadic households in Qinghai, China. The study found that cooking is the primary factor influencing acute carbon monoxide (CO) exposure among women, while heating alone is sufficient to elevate CO exposure above WHO guidelines. The results suggest that cooking-only interventions have the potential to reduce HAP exposure among women, but solutions for both cooking and heating may be required to reduce COHb to below WHO guidelines. This study’s findings may inform future interventions for fuel and stove selection to reduce HAP and exposure among other populations.

Validation of Noninvasive Methemoglobin and Carboxyhemoglobin Measurements Using Pulse Co-Oximeter in Healthy Dogs.

To assess the agreement between pulse co-oximeter and blood co-oximeter in measuring methemoglobin (MetHb) and carboxyhemoglobin (COHb) in healthy, awake dogs. Forty-five healthy dogs were enrolled in the study. Pulse co-oximetry was performed using the Masimo Radical 7 Pulse Co-Oximeter with a Rainbow® adhesive sensor. Simultaneously, venous blood samples were collected, and MetHb and COHb were immediately measured using a Stat Profile Prime Plus VET Critical Care Analyzer. Paired measurements of MetHb and COHb were evaluated via Spearman correlation, intra-class correlation (ICC), and Bland-Altman plots to evaluate the degree of agreement between the pulse co-oximeter and the blood co-oximeter. A total of 45 paired MetHb and COHb measurements were collected. There was a weak correlation between the pulse co-oximeter and the blood co-oximeter readings. The correlation coefficients for MetHb and COHb were 0.0 (95% CI, -0.3 to 0.3) and 0.03 (95% CI, -0.27 to 0.32), respectively. The ICC indicated poor agreement between the pulse and blood co-oximeter for MetHb (ICC = 0.00, 95% CI: -0.12 to 0.15) and COHb (ICC = 0.03, 95% CI: -0.27 to 0.33). Bland-Altman plots revealed low mean bias but wide limits of agreement, indicating that the pulse co-oximeter overestimated MetHb by on average of 0.7% (P < 0.0001) (95% LoA: -0.5 to 2.0) and COHb by on average 0.2% (P = 0.59) (95% LoA: -4.6 to 5.0). Obtaining MetHb and COHb measurements with the Masimo Radical 7 Pulse Co-Oximeter is straightforward in healthy, awake dogs. However, the device does not provide accurate measurements compared to the blood co-oximeter, specifically in the range of MetHb and COHb in healthy dogs, based on the wide LoA.

Perinatal carbon monoxide poisoning with fetal and maternal carboxyhemoglobin measurements.

Perinatal carbon monoxide poisoning with fetal and maternal carboxyhemoglobin measurements.

A New Delayed Hemolysis Transfusion Diagnosis Score Based on Intra Vascular Hemolysis Parameters

Introduction Delayed hemolysis transfusion reaction (DHTR) is a serious complication of sickle cell disease (SCD), accounting for 6% of all-cause mortality (Habibi Am J Hematol 2016). Although transfusion risk management has improved, the diagnosis of DHTR remains difficult and has long been underestimated. In fact, the main manifestation of DHTR in SCD patients is vaso-occlusive crisis (VOC), often associated with acute chest syndrome (ACS) and multiorgan failure, which makes transfusion attribution somewhat difficult. DHTR treatment, although not yet well codified, is based on immunoglobulins, corticoids or eculizumab in severe forms, depending on the team (Pirenne Blood 2018). Our team has proposed the use of a nomogram to guide diagnosis based on HbA decline (calculated by multiplying HbA and MCH) (Mekontso Dessap Am J Hematol 2016). However, this requires rapid quantification of hemoglobin fractions (often by HPLC) and a post-transfusion reference value, which is often lacking. Given the precise measurement of intravascular markers of hemolysis by spectroscopy that we have developed, we wondered if this could provide a simpler and faster diagnostic tool for DHTR. We performed a cross-sectional cohort study to test this hypothesis. Methods We performed intravascular hemolysis assays, including measurement of plasma hemoglobin, heme, methemoglobin, carboxyhemoglobin, hemopexin, and bilirubin, in a single run on thawed samples from patients in different cohorts. In short, the method combines a biochemical and mathematical multistep analysis (BET 18P3417). Cohorts of patients experiencing a DHTR were compared with patients in steady state and patients at the time of acute chest syndrome (ACS) in the ICU. Patients gave informed consent in accordance with French law (SCD transfu, Erythropedie, FCDREP and TASC cohorts). Two experts independently reviewed all DHTR cases to retrospectively confirm the diagnosis. Logistic regression with k-fold cross-validation (3-fold) was applied to a dataset containing hemolytic biomarkers to predict the occurrence of DHTR using python3 and the sklearn library. The performance of the model was evaluated using various metrics such as accuracy and area under the ROC curve (AUC). Specificity, sensitivity, positive predictive value (PPV) and negative predictive value (NPV) were also calculated. The confusion matrix table shows the predictive performance of the model for the classification of DHTR occurrence. Results Samples and clinical data of 53 SCD patients with DHTR, Y patients at steady state, and Z patients during acute chest syndrome were analyzed and included in this study. During DHTR plasma Hemoglobin (47.8 vs 12.8 µM, p&amp;lt;0.0001), Heme (27.9 vs 3.2 µM, p&amp;lt;0.0001), Heme/Hemoglobin ratio (1.02 vs 0.4 ; p&amp;lt;0.0001), MetHb (11.7 vs 2.6 µM, p=0.0003) were significantly higher in DHTR whereas Hemopexin level was lower (1.53 µM vs 2.7 µM, p=0.03) A diagnostic score was obtained by combining plasma levels of hemoglobin, heme, HbCO, MetHb, bilirubin, hemopexin. The AUC was 0.86 with a mean identical cross-validation. The accuracy and precision of the score were 0.85 and 0.76, respectively. The specificity was 0.93, the sensitivity was 0.66, the positive predictive value (PPV) was 0.76 and the negative predictive value (NPV) was 0.88. Conclusions This score may help clinicians diagnose DHTR early and then provide appropriate treatment. However, a prospective study is needed to validate the score.

Impact of Methemoglobin on Carboxyhemoglobin Saturation Measurement in Fatal Sodium Nitrate and Sodium Nitrite Cases.

An increase in suicide cases by sodium nitrate and sodium nitrite ingestion has been noted in the scientific literature. We report on the possible impact of nitrate/nitrite-caused methemoglobinemia on carboxyhemoglobin measurement by spectrophotometric methods. Elevated methemoglobin saturation may result in insufficient reducing agent to convert methemoglobin to deoxygenated hemoglobin, affecting the measured total hemoglobin and carboxyhemoglobin saturation. We highlight four cases where the cause of death was attributed to sodium nitrate or sodium nitrite ingestion. The the possible impact of the nitrate/nitrite-caused methemoglobinemia on the carboxyhemoglobin saturation as measured by spectrophotometry is discussed. Further studies are needed to identify a causal relationship between nitrate/nitrite-caused methemoglobinemia on carboboxyhemoglobing saturation as measured by spectrophotometric methods.

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 (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.

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.

Carbon Monoxide Poisoning Death in the Wild Environment in Tropical Areas: a Case Report

Carbon monoxide (CO) poisoning is a major public health concern and a common cause of death. Deaths caused by carbon monoxide poisoning in the wild of tropics are rare and special. In this case, the measurement of percentage carboxyhemoglobin in the heart blood of the deceased was only 17.5%. After eliminating the causes of death such as self disease, mechanical injury, mechanical asphyxia and other toxicosis, the body was considered to have died from CO poisoning. The particularity of this case can prompt the identification thinking and broaden the judgment method for forensic scientists suspected of CO poisoning death.

The Trend of Arterial Carboxyhemoglobin in Non-smokers as a Prognostic Tool in Severe COVID-19 Patients: A Single-Centre Prospective Study.

Introduction Carboxyhemoglobinemia is characterised by decreased oxygen delivery to tissues. In severe and critical coronavirus disease 2019 (COVID-19) illness withhypoxia, this can herald a grave and protracted course of illness. Patients with COVID-19 experience respiratory impairment, lowering the pace at which carbon monoxide (CO) is eliminated and raising the likelihood of carboxyhemoglobinemia. We set out to exploreearly arterial carboxyhemoglobin (COHb) and COVID-19 patient outcomes in non-smokers andits potential as a predictive tool for mortality. Methods Forty-five patients, non-smokers with severe/critical severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection requiring admission in a North Indian 1200-bedded tertiary care hospital, were recruited prospectively from October 2020 to March 2021. Arterial COHb% was evaluated with arterial blood gases using an analyser, which were taken at the time of admission and then every alternate day for the first 10 days. Carboxyhemoglobinemia was defined as COHb% more than 1%. The primary outcome was defined as the patient's hospital outcome (survivor/non-survivor). Results Of the total 45 subjects, 51.1% (n=23) survived. Patients developed carboxyhemoglobinemia with an incidence of 51% during the course of their hospital stay. The mean ± SD of COHb% on admission was 1.0 ± 0.58 and 1.03 ± 0.8 in non-survivors and survivors, respectively (p=0.870). Maximal individual values of 5.3%and 6.1% were seen in survivors and non-survivors, respectively. On serial COHb measurement, non-survivors had significantly higher COHb% on days 6 and 10. No co-relation of COHb% with inflammatory markers was noted. Conclusion Arterial COHb levels in non-survivors were significantly higher than in survivors on days 6 and 10. Our study did not show a prognostic value of serial COHb measurement inpatients with severe COVID-19. To establish COHb as a predictive marker in severely ill COVID-19 patients, additional research is required.

Three cases of clinically significant inaccurate carboxyhemoglobin measurement

Background: Clinicians often rely on measurement of carboxyhemoglobin (COHb) to confirm or rule out a diagnosis of carbon monoxide (CO) poisoning. Methods: We report two cases of false negative COHb in patients with CO poisoning and one case of false positive COHb in a patient without CO poisoning. Results: In the first case, a 20-year-old male developed headache, confusion, and near-syncope while operating a gasoline-powered pressure washer in an enclosed space. In the emergency department (ED), his COHb was 1.8%, but this level was disregarded, and he was referred for hyperbaric oxygen. His COHb just before hyperbaric oxygen was 4.1%, and later analysis of his blood collected at ED arrival revealed a COHb of 20.1%. The referral ED blood gas machine calibration and controls were within specification. In the second case, a 45-year-old male presented with several others to the ED with symptoms of CO poisoning after exposure at a conference. All others had elevated COHb levels, but his COHb was 2%. He was discharged but returned shortly with continued symptoms and requested his COHb be repeated. The repeat COHb was 17% (84 minutes after the first). After three hours of oxygen, his COHb was 7%. In the final case, an 83-year-old non-smoking male presented to an ED with breathlessness and tachypnea and was diagnosed with COVID-19 pneumonia. His COHb was 7.1%, but he reported living in an all-electric home. Another adult who lived with him and rode with him to the ED was asymptomatic and had a COHb of 3%. Later, COHb of 1.9% was measured from blood collected at ED arrival, and gas chromatography/mass spectrometry confirmed this result (2%). Conclusions: COHb levels are not always accurate. Clinicians should use clinical judgment to manage their patients, including rejecting laboratory values that do not fit the clinical situation.

Exploring Health Impacts of Occupational Exposure to Carbon Monoxide in the Labour Community of Hattar Industrial Estate

This study was designed to assess the health impacts related to noninvasive carbon monoxide saturation (SPCO %) in the blood of respondents. For this purpose, 150 respondents from the labour community of Hattar Industrial Estate (testing site) and 100 respondents from Sultan Pur (control site) were selected. To achieve this objective, a Rad-57 Pulse CO-Oximeter was used for noninvasive carboxyhemoglobin measurement. Carbon monoxide saturation (SPCO%) in the blood of respondents from Hattar Industrial Estate, Haripur, Pakistan has been compared with the WHO’s standard concentration of SPCO% (5%). High saturation of carbon monoxide (carboxyhemoglobin SPCO) in the blood of respondents and disease association have been interpreted in graphs formed on the basis of statistical analysis in terms of frequencies, using statistical software (SPSS), based on demographic entries as well as exposure time of the employees in the processing, food and steel industries. The highest SPCO% measured was 17% in the steel industry and the lowest measured level was 4.2%. Frequencies and percentages of respiratory inflammation, dermatosis, asthma, breathing issues and eye inflammation among respondents were 29%, 35%, 16.7%, 23.5% and 9%, respectively. Prevalence of disease in three different groups of respondents (from three testing sites) was also analyzed on the basis of exposure time (hrs.) to carbon monoxide emissions. Prevalence of disease among the exposed and non-exposed groups was analyzed and showed comparatively lower disease prevalence in the group of respondents who were not exposed to high carbon monoxide emissions. The data of the current study was also subjected to statistical modelling to find the health risk of air pollutants (carbon monoxide) on population health by calculating attributable risk (AR) or attributable proportion (AP). Results indicated that attributable risk of carbon monoxide exposure for respiratory diseases, dermatosis and eye inflammation were 61.12%, 65.77% and 24.95% respectively. Findings of statistical modelling indicated that dermatosis and respiratory diseases were more prevalent in laborers of industrial units than those at control site.

Correlation between Non-invasive Measurement of Carboxyhemoglobin and Bilirubin Level Measurement in Near- Term and Term Neonates as a Predictor of Neonatal Hemolysis

Abstract Background Neonatal hyperbilirubinemia is common in the neonatal period. Yet, serious pathological hyperbilirubinemia may cause kernicterus with detrimental neurologic sequalae. Carbon monoxide (CO) is the byproduct of the breakdown of heme, it is transported as carboxyhemoglobin to the lungs to be exhaled. Thus, carboxyhemoglobin levels increase as a result of hemolysis, and is therefore considered a sensitive index for the degree and severity of the subsequent hyperbilirubinemia. Objectives To correlate between non-invasive carboxyhemoglobin levels and bilirubin levels in near-term and tem neonates starting hour I of life. Subjects and methods A total of 100 near-term and term neonates were studied, by measuring carboxyhemoglobin by a Pulse CO-oximetry and serum bilirubin level (hour l) and transcutaneous bilirubin (TcB) hourly since birth for the I st 6 hours then every 6 hours till the time of discharge in a cross sectional case-control study. Results A cut off value of 4 for non-invasive carboxyhemoglobin with sensitivity of 81.25%, specificity of 95.24% was found to the earliest non-invasive predictor for subsequent jaundice. In patients with proven hemolysis, carboxyhemoglobin when compared to TcB was found to increase significantly in the first 3 hours of life more than TcB, stalting hour 4 till time of discharge it was increased yet statistically insignificant Conclusion We found that non-invasive carboxyhemoglobin is an effective early predictor for subsequent jaundice starting first hour of life. It can be used as a screening tool for hemolytic jaundice especially in hospitals with early discharge policy.

Comparison of Spectrophotometric Methods for the Determination of Carboxyhemoglobin in Postmortem Blood.

Carbon monoxide (CO) poisoning presents an interesting challenge for postmortem toxicology laboratories. The discontinuation of the CO-oximeter manufactured by Instrumentation Laboratories has left many forensic laboratories without this simple but reliable choice for the analysis of CO in blood. A comparable alternative that is quick and simple is analysis using a standard ultraviolet-visible spectrophotometer, which offers sufficient precision and accuracy for the measurement of percentage carboxyhemoglobin (%COHb) in postmortem blood. The hurdle for laboratories then becomes the selection of an appropriate spectrophotometric method since a variety of procedures have been published over the years. Four methods were evaluated based on literature findings and/or the appropriateness for postmortem testing. These methods are based on (i) relating %COHb to the ratio of COHb and Hb absorbance of a two-component system (two wavelengths), (ii) the multicomponent analysis of all hemoglobin species, (iii) the multicomponent analysis of a two-component system, and (iv) derivative spectroscopy. While all four methods performed similarly in terms of typical validation requirements, the ability to more effectively handle decomposed samples and the ease of sample preparation afforded (v) the multicomponent analysis of a two-component system-the most suitable for routine postmortem testing.

ECG Intervals on Acute Carbon Monoxide Poisoning.

To evaluate the usability of electrocardiography (ECG) intervals in the diagnosis and treatment monitoring of acute carbon monoxide (CO) poisoning. An observational study. Department of Emergency Medicine, Kayseri City Hospital, Turkey, from November 2018 to May 2019. Each of 80 patients for study and control groups were prospectively included. For study group, pre- and post-treatment ECG intervals (P-wave and QRS complex periods, PP, PR, RR, QT, and QTc intervals) and carboxyhemoglobin (COHb) levels of the patients were evaluated. For control group, ECG intervals and COHb levels of the patients during admission to the Emergency Department were evaluated. As a result of the statistical analysis in which measurements of the study group and control group were compared, a statistically significant difference was found in the following values: pre-treatment group COHb level (p<0.001), PR interval (p=0.046), PP interval (p<0.001), QT interval (p<0.001), QTC interval (p=0.016), RR interval (p<0.001), and post-treatment group COHb level (p<0.001), PR interval (p=0.009), PP interval (p=0.041), QTC interval (p=0.010), and RR interval (p=0.036). QT interval values in the post-treatment group were similar to those of the control group (p=0.342). In the ROC analysis where the diagnostic performance of ECG intervals was evaluated, the area under the curve (AUC) scale was between 0.29 and 0.62. ECG intervals do not provide as much benefit as COHb measurement in the diagnosis of acute CO poisoning. However, the QT interval is a useful ECG interval in the treatment monitoring of acute CO poisoning. Key Words: Acute carbonmonoxide poisoning, ECG interval, QT interval, Emergency Department.

Data validation of non- invasive carboxyhemoglobin measurement in recipient blood using numerical modeling data: a case of Himalayan regions' households of Nepal.

Carbon monoxide decreases the oxygen carrying capacity of blood. As a result, it reduces the supply of oxygen into body cells and tissues including vital organs. It is poisonous during pregnancy as it leads to high risk for the mother and foetus. It causes the developmental disorders, cerebral anoxic lesions and even death of foetus. The major aim of this study is to validate the non- invasive % COHb monitored data with modelled data. IAQ instruments are administered to monitor CO concentraction and % COHb level in recipient's blood. Thus, the level of % COHb in blood is approximated using numerical modeling to validate the monitored data with modeled data. Twenty four hours average CO concentration with TCS house is found 8.65 ± 7.77ppm, 7.39 ± 5.62ppm, 6.69 ± 7.16ppm, 4.76 ± 7.19ppm, 4.48 ± 6.10ppm in the order of case II > case I > case V > case III > case IV, respectively. Twenty four hours average CO concentration with ICS house is found 3.54 ± 4.41ppm, 2.41 ± 3.93ppm, 2.30 ± 2.24ppm, 1.70 ± 2.93ppm and 1.51 ± 1.24ppm in the order of case I > case V > case II > case IV > case III respectively. The average CO concentration in breath by cook is found 3.75 (3.75 ± 2.35)ppm in ICS using house and 5.36 (5.36 ± 4.54)ppm in TCS using house with minimum 0.60ppm and maximum 31.34ppm. The CO exposure is found more than 13h a day for TCS using house and 9h a day for ICS using house. The average cook_CO exposure is found 5.36 (5.36 ± 4.54)ppm and 3.75 (3.75 ± 2.35)ppm in sampled house using TCS and ICS respectively. The average percentage COHb in sampled house using TCS and ICS is found 4.31 (4.3 ± 5.35) % and 3.72 (3.72 ± 2.67) % respectively. The correlation between numerical modelling of COHb with non- invasive COHb measurement is found significant i.e. P value <0.00001 establishing r2 value 0.95 and 0.97 for ICS and TCS using house respectively.

Carbon monoxide exposures reported to the UK National Poisons Information Service: a 4-year study.

Unintentional carbon monoxide (CO) poisoning poses a public health challenge. The UK National Poisons Information Service (NPIS) provides advice to healthcare professionals via the online database, TOXBASE®, and a 24-hour telephone line. Our aim was to analyse all CO-related enquiries to the NPIS. We analysed enquiries regarding unintentional CO exposure (1st July 2015-30th June 2019). Information on patient demographics, CO source and location, clinical features and poisoning severity was collected from telephone enquiries and TOXBASE accesses. 2970 unintentional non-fire-related CO exposures were reported. Exposures occurred commonly in the home (60%) with faulty boilers frequently implicated (27.4%). Although five fatalities were reported, 68.7% of patients experienced no or minor symptoms only (headache most frequently reported). Despite being the gold standard measurement, blood carboxyhaemoglobin concentration was only recorded in 25.6% patients, with no statistically significant correlation with severity. Unintentional CO exposures in the UK commonly occur in domestic settings and although are generally of low severity, fatalities continue to occur. Carboxyhaemoglobin measurement is important to confirm exposure but further work is required to assess its validity as a prognostic indicator in CO exposure. Public health policy should continue to focus on raising awareness of the dangers of CO.

Clinical Factors Influencing Endogenous Carbon Monoxide Production and Carboxyhemoglobin Levels in Neonates.

Carboxyhemoglobin (COHb) is an index of endogenous carbon monoxide formation during the hem degradation process and could be used to confirm hemolysis in neonates. The influence of other clinical factors on COHb values in neonates has not been fully investigated. We aimed to evaluate the influence of hemolysis, sepsis, respiratory distress, and postnatal age on COHb values. We retrospectively analyzed COHb measurements determined with a carbon monoxide-oximeter in 4 groups of term neonates: A-sepsis, B-respiratory distress, C-hemolysis, and D-healthy neonates. The mean COHb values were 1.41% (SD: 0.26), 1.32% (SD: 0.27), 2.5% (SD: 0.69), and 1.27% (SD: 0.19) (P<0.001) in groups A (n=8), B (n=37), C (n=16), and D (n=76), respectively. COHb in group C was significantly higher than in the other groups. There was a negative correlation between postnatal age and COHb in healthy neonates. A cut-off level of 1.7% had 93% (95% confidence interval [CI]: 89%-97%) sensitivity and 94% (95% CI: 90%-98%) specificity for diagnosis of hemolysis. COHb values were higher during the first days of life. We found that COHb levels in neonates with hemolysis were significantly higher and that the influence of sepsis and respiratory distress on COHb values was insignificant.

Non-invasive monitoring of carboxyhemoglobin during hyperbaric oxygen therapy

Introduction: This study aimed to assess the capability of a pulse CO-oximeter to continuously monitor carboxyhemoglobin (COHb) during hyperbaric oxygen (HBO2) therapy. We estimated limits of agreement (LOA) between blood gas analysis and pulse CO-oximeter for COHb during HBO2 therapy in patients suffering from acute CO poisoning. Furthermore, we did a medicotechnical evaluation of the pulse CO-oximeter in hyperbaric conditions. Method: We conducted a prospective, non-clinical, observational study in which we included n=10 patients with acute CO poisoning referred for HBO2 therapy. We did five repeated measurements of COHb for each patient during the HBO2 therapy. Bland-Altman analysis for multiple observations per individual was used to assess the agreement. The a priori LOA was ±6% for COHb. For the medicotechnical evaluation continuous measurements were obtained throughout each complete HBO2 therapy. The measurements were visually inspected and evaluated. Results: The Bland-Altman analysis showed that the pulse CO-oximeter overestimated COHb by 2.9 % [±1.0%] and the LOA was ±7.3% [±1.8%]. The continuous measurements by pulse CO-oximetry showed fluctuating levels of COHb and summarized saturations reached levels above 100%. Measurements were not affected by changes in pressure. Conclusion: To our knowledge, this study is the first to assess LOA and demonstrate use of a non-invasive method to measure COHb during HBO2 therapy. The pulse CO-oximeter performed within the manufactures reported LOA (±6%) despite hyperbaric conditions and was unaffected by changes in pressure. However, summarized saturations reached levels above 100%.