Biomarkers of Waterpipe Tobacco Smoke Exposure: A Systematic Review and Meta-Analysis.

INTRODUCTION: The prevalence of waterpipe tobacco smoking is increasing globally. Biomarkers of waterpipe tobacco smoke (WTS) exposure are less studied. AIMS AND METHODS: To identify the types of biomarkers of WTS exposure and estimate changes in biomarker concentrations pre- to post-WTS exposure. PubMed, Embase, Web of Science, CINAHL Plus, PsycINFO, and Cochrane Library were searched for studies up to April 24, 2023. The types of biomarkers were identified. Random-effects models were used to estimate changes in biomarker concentrations pre- to post-WTS exposure. RESULTS: Seventy-three studies involving 3755 participants exposed to WTS (49% male, mean age: 24.8 years) and 11 types of biomarkers of WTS exposure were identified. The biomarkers included tobacco alkaloids, expired carbon monoxide (eCO), carboxyhemoglobin (COHb), tobacco-specific nitrosamines, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), heavy metals, unmetabolized VOCs, unmetabolized PAHs, furan metabolites, and heterocyclic aromatic amines. Compared with pre-WTS exposure, eCO (breath; mean difference [MD] 27.00 ppm; 95% confidence interval [CI]: 20.91 to 33.08), COHb (blood; MD 4.30%; 95%CI: 2.57 to 6.03), COHb (breath; MD 7.14%; 95%CI: 4.96 to 9.31), nicotine (blood; MD 8.23 ng/mL; 95%CI: 6.27 to 10.19), and cotinine (urine; MD 110.40 ng/mL; 95%CI: 46.26 to 174.54) significantly increased post-WTS exposure. CONCLUSIONS: Biomarkers of WTS exposure were systematically identified. The similarity between the biomarkers of WTS exposure and those of cigarette smoke and higher concentrations of some biomarkers post-WTS exposure underscore the need for further research on applying biomarkers in surveillance, interventions, and regulations to mitigate the harms of waterpipe tobacco smoking. IMPLICATIONS: This study provides the first comprehensive overview of biomarkers investigated and available for assessing WTS exposure and their concentration changes in the human body. Researchers can use biomarkers such as eCO, COHb, nicotine, and cotinine to measure the health risks associated with WTS exposure and objectively evaluate the effectiveness of public health interventions aimed at reducing waterpipe tobacco smoking. Public health policymaking can also be informed through increased biomarker concentrations following WTS exposure, to implement regulations and public health education campaigns on limiting or preventing waterpipe tobacco smoking.

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.

Development of a risk prediction nomogram for delayed neuropsychiatric sequelae in patients with acute carbon monoxide poisoning.

OBJECTIVES: Delayed neuropsychiatric sequelae (DNS) are critical complications following acute carbon monoxide (CO) poisoning that can substantially affect the patient's life. Identifying high-risk patients for developing DNS may improve the quality of follow-up care. To date, the predictive DNS determinants are still controversial. Consequently, this study aimed to construct a practical nomogram for predicting DNS in acute CO-poisoned patients. METHODS: This retrospective study was conducted on patients with acute CO poisoning admitted to the Tanta University Poison Control Center (TUPCC) from December 2018 to December 2022. Demographic, toxicological, and initial clinical characteristics data, as well as laboratory investigation results, were recorded for the included patients. After acute recovery, patients were followed up for six months and categorized into patients with and without DNS. RESULTS: Out of 174 enrolled patients, 38 (21.8%) developed DNS. The initial Glasgow Coma Scale (GCS), carboxyhemoglobin (COHb) level, CO exposure duration, oxygen saturation, PaCO2, and pulse rate were significantly associated with DNS development by univariate analysis. However, the constructed nomogram based on the multivariable regression analysis included three parameters: duration of CO exposure, COHb level, and GCS with adjusted odd ratios of 1.453 (95% CI: 1.116-1.892), 1.262 (95% CI: 1.126-1.415), and 0.619 (95% CI: 0.486-0.787), respectively. The internal validation of the nomogram exhibited excellent discrimination (area under the curve [AUC] = 0.962), good calibration, and satisfactory decision curve analysis for predicting the DNS probability. CONCLUSIONS: The proposed nomogram could be considered a simple, precise, and applicable tool to predict DNS development in acute CO-poisoned patients.

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.

The Relationship between Fragmented QRS and Myocardial Injury in Patients with Acute Carbon Monoxide Poisoning.

Background and Objectives: Carbon monoxide (CO) intoxication is one of the most common causes of poisoning-related deaths and complications. Myocardial injury is an important complication of CO poisoning. In our study, we aimed to evaluate the relationship between the presence and prevalence of fragmented QRS (fQRS) and myocardial injury in patients with CO intoxication. Materials and Methods: We retrospectively evaluated patients who presented to the emergency department of our tertiary care center with CO intoxication between January 2020 and December 2023. In our study, we performed subgroup analyses according to the presence of myocardial injury and fQRS. We evaluated the parameters and risk factors associated with myocardial injury. Results: Myocardial injury was detected in 44 patients, and fQRS was detected in 38 patients. In the myocardial injury (+) group, the fQRS rate was 38.6%, and the median number of leads with fQRS was 3 (2-6) and was significantly higher than in the myocardial injury (-) group (p < 0.001). We found that carboxyhemoglobin had a significant positive correlation with troponin (p = 0.001) and pro-B-type natriuretic peptide (proBNP) (p = 0.009). As a result of multivariate analysis, we determined that age, creatinine, proBNP, fQRS, and ≥3 leads with fQRS are independent risk factors for myocardial injury. Conclusions: Myocardial injury in CO intoxication patients is associated with proBNP, the presence of fQRS, and the number of leads with fQRS. Age, creatinine level, proBNP, the presence of fQRS, and ≥3 leads with fQRS are independent risk factors for myocardial injury in patients with CO intoxication.

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.

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.

Carboxyhemoglobin as biomarker of late-onset sepsis in preterm infants.

Carboxyhemoglobin (COHb) is considered a biomarker of oxidative stress and previous studies reported an increase in COHb levels in preterm infants who develop late-onset sepsis (LOS). Our aim was to assess the correlation between COHb levels and the risk for LOS development. We retrospectively studied 100 preterm infants, 50 in the LOS and 50 in the no LOS group. COHb levels were measured on the day of diagnosis of the first episode of LOS, 3, 2, and 1 days before and 1 and 4 days after the onset of LOS. Logistic regression analysis showed that a higher level of COHb 2 days before the diagnosis of LOS increases the risk for LOS development (OR 12.150, 95% Cl 1.311-12.605; P = 0.028). A COHb level of 1.55% measured 2 days before the diagnosis of LOS is the best predictive threshold for LOS with a sensitivity of 70% and a specificity of 70%.    Conclusion: Increased levels of COHb may predict the diagnosis of LOS in very preterm infants with a good accuracy. If further studies confirm our findings, this easy-to-measure biomarker could provide neonatologists with another tool for monitoring and early diagnosis of sepsis in high-risk patients. What is Known: • Carboxyhemoglobin (COHb) is a biomarker of oxidative stress. • Previous studies reported an increase in COHb levels in preterm infants who develop late-onset sepsis (LOS). What is New: • COHb levels increased two days before the diagnosis of LOS and this increase was associated with the risk for developing LOS. • ROC curve analysis for COHb measured two days before the diagnosis of LOS showed that 1.55% is the best predictive threshold for LOS with a sensitivity of 70% and a specificity of 70%.

The effect of posture and exercise on blood CO kinetics during the optimized carbon monoxide rebreathing procedure.

An indispensable precondition for the determination of hemoglobin mass (Hbmass) and blood volume by CO rebreathing is complete mixing of CO in the blood. The aim of this study was to demonstrate the kinetics of CO in capillary and venous blood in different body positions and during moderate exercise. Six young subjects (4 male, 2 female) performed three 2-min CO rebreathing tests in seated (SEA) & supine (SUP) positions as well as during moderate exercise (EX) on a bicycle ergometer. Before, during, and until 15 min after CO rebreathing cubital venous and capillary blood samples were collected simultaneously and COHb% was determined. COHb% kinetics were significantly slower in SEA than in SUP or EX. Identical COHb% in capillary and venous blood were reached in SEA after 5.0 ± 2.3 min, in SUP after 3.2 ± 1.3 min and in EX after 1.9 ± 1.2 min (EX vs. SEA p < .01, SUP vs. SEA p < .05). After 7th min, Hbmass did not differ between the resting positions (capillary: SEA 766 ± 217 g, SUP 761 ± 227 g; venous: SEA 759 ± 224 g, SUP 744 ± 207 g). Under exercise, however, a higher Hbmass (p < .05) was determined (capillary: 823 ± 221 g, venous: 804 ± 226 g). In blood, the CO mixing time in the supine position is significantly shorter than in the seated position. By the 6th minute complete mixing is achieved in either position giving similar Hbmass determinations. CO-rebreathing under exercise conditions, however, leads to ∼7% higher Hbmass values.

Screening patients for unintentional carbon monoxide exposure in the Emergency Department: a cross-sectional multi-centre study.

BACKGROUND: Low-level exposure to carbon monoxide (CO) is a significant health concern but is difficult to diagnose. This main study aim was to establish the prevalence of low-level CO poisoning in Emergency Department (ED) patients. METHODS: A prospective cross-sectional study of patients with symptoms of CO exposure was conducted in four UK EDs between December 2018 and March 2020. Data on symptoms, a CO screening tool and carboxyhaemoglobin were collected. An investigation of participants' homes was undertaken to identify sources of CO exposure. RESULTS: Based on an ED assessment of 4175 participants, the prevalence of suspected CO exposure was 0.62% (95% CI; 0.41-0.91%). CO testing in homes confirmed 1 case of CO presence and 21 probable cases. Normal levels of carboxyhaemoglobin were found in 19 cases of probable exposure and in the confirmed case. CONCLUSION: This study provides evidence that ED patients with symptoms suggestive of CO poisoning but no history of CO exposure are at risk from CO poisoning. The findings suggest components of the CO screening tool may be an indicator of CO exposure over and above elevated COHb. Clinicians should have a high index of suspicion for CO exposure so that this important diagnosis is not missed.

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.

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.

Carboxyhaemoglobin levels in infants with hypoxic ischaemic encephalopathy.

OBJECTIVES: Hypoxic ischaemic encephalopathy (HIE) is associated with oxidative stress. A potential marker of oxidative damage is carboxyhaemoglobin (COHb) which is the product of the reaction between carbon monoxide and haemoglobin and is routinely assessed on blood gas analysis. Our objective was to test the hypothesis that higher COHb levels would be associated with worse outcomes in infants treated for HIE. METHODS: A retrospective, observational study was performed of all infants who received whole body hypothermia for HIE at a tertiary neonatal intensive care unit between January 2018 and August 2021. For each participating infant, the highest COHb level per day was recorded for days one, three and five after birth. RESULTS: During the study period, 67 infants with a median (IQR) gestational age of 40 (38-41) weeks underwent therapeutic hypothermia for HIE. The median (IQR) COHb level on day three was higher in infants without electroencephalographic seizures (1.4 [1.1-1.4] %) compared with infants with seizures (1.1 [0.9-1.3] %, p=0.024). The median (IQR) COHb on day five was higher in infants without MRI brain abnormalities (1.4 [1.2-1.7] %) compared with infants with MRI abnormalities (1.2 [1.0-1.4] %, p=0.032). The COHb level was not significantly different between the nine infants who died compared to the infants who survived. CONCLUSIONS: COHb levels were higher in infants with HIE without seizures and in those with normal MRI brain examinations. We suggest that carbon monoxide has a potential protective role in HIE.

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.

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.

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.

[Investigation of a carbon monoxide poisoning accident with a hidden source].

In June 2022, a carbon monoxide poisoning accident with hidden source occurred in a bonded gold/silver wire manufacturing enterprise in Guangzhou, causing 10 people to be poisoned, of which 1 was caused by carbon monoxide poisoning and 9 by carbon monoxide contact reaction. The symptoms were dizziness, fatigue and vomiting. After 5 to 7 h, the saturation of carboxyhemoglobin in finger pulse was 4% to 10%, and the saturation of carboxyhemoglobin in blood gas biochemical analysis was 1.9% to 5.8%. The concentration of carbon monoxide detected in the carbon borne purification plant of the enterprise was 34.46-37.26 mg/m(3). It was judged that the accident was carbon monoxide poisoning caused by carbon monoxide gas being transported to the work post along the gas transmission pipeline due to abnormal operation of the carbon borne purification plant. By investigating the source and cause of poison, this paper provides a warning for the similar process to prevent similar events, and provides a new idea for the identification of chemical poisoning risk. At the same time, it is warned that similar enterprises should fully consider the risk of poisoning under specific circumstances, strengthen equipment maintenance and repair, and prevent the occurrence of similar incidents.

Breaking Stereotypes: Polycythemia Secondary to Shisha Smoking in a Middle-Age Swiss Woman.

The diagnosis of polycythemia, particularly the secondary forms, can be challenging. The distinction between primary and secondary polycythemia is relevant and has management implications. A systematic diagnostic workup algorithm and a good anamnesis are of paramount relevance. More than one cause may be involved in the development of polycythemia, identifying all of them will be the key to better understanding and eventually solving the polycythemia. We describe a case of a 53-year-old Swiss woman with polycythemia and a high level of carboxyhemoglobin. Her medical story included obesity and obstructive sleep apnea. The anamnesis ruled out the habit of smoking cigarettes; however, the patient reported that she was on a trip to Egypt 10 years before and bought herself a shisha; since then, she used to smoke shisha daily, at home, alone. After drastically reducing and then stopping the shisha smoking, 7 months later her blood count and carboxyhemoglobin completely normalized.

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.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.