Postmortem concentrations for total blood carbon monoxide (TBCO) as novel biomarker for carbon monoxide (CO) poisonings

Total Blood Carbon Monoxide (TBCO) showed promising results in improving accuracy of CO determinations in blood and presenting better stability to different storage conditions. Therefore, it was proposed as alternative biomarker to carboxyhemoglobin (COHb) for CO poisoning diagnosis. However, given that current interpretation reference values exist for COHb only, it is difficult to implement TBCO analysis in routine. Therefore, we aimed at determining TBCO reference values for postmortem CO poisoning cases. A previously validated method for TBCO analysis via gas chromatography-mass spectrometry was applied to cardiac, peripheral, cranial and spleen blood samples collected from 92 autopsies. Autopsy cases included 21 non-CO related and 71 CO-related cases with varying postmortem intervals (PMI). Statistical analyses were performed using statistical software R Studio. When comparing lower to higher PMI for non-CO related cases, no significant differences were found, which suggests that CO formation or degradation at low PMIs does not occur. Spleen blood showed potential as alternative matrix for CO determinations in cases with sample availability issues, but needs to be evaluated for CO positive cases. Results for cardiac blood in CO-related autopsies showed a positive correlation between COHb and TBCO values (R = 0.78). This value is lower than what is found in the literature, suggesting that even though COHb and TBCO are correlated, a potential underestimation of the true CO exposure might occur if only COHb values are taken into consideration. Samples were divided into CO exposure groups based on COHb concentrations and with the data obtained, classification into following TBCO concentration groups are proposed: no significant CO exposure case <6 µmol/mL, medium CO exposure case 6-20 µmol/mL, high CO exposure case >20µmol/mL. Even if a higher number of samples in each group would enable to increase the confidence, these results are very promising and highlight the importance of TBCO measurement.

Nicotine Free Herbal Composition for Smoking De-Addiction - A Placebo Controlled, Double Blind, Randomized, Multicentric Clinical Study

Background

Smoking is a major predisposing factor for many health problems including cancers, vascular disorders, etc., To quit smoking is the only solution to prevent them. Various medicinal and non-medicinal methods are used worldwide for the same. The present study evaluates the effect of a nicotine free herbal formulation containing ingredients like Mucuna pruriens, Withania somnifera, Bacopa monnieri, etc., for cessation of smoking and its effects on other health parameters related to smoking.

Materials and Methods

The present study was a placebo controlled, double blind, randomized, and multi-centric clinical study conducted at three clinical sites in India. After ethical approval and informed consent, all participants were given Smotect Tablets or Placebo tablets in a dose of 2 tablets twice daily for 90 days. A total of 103 participants (52 in trial group and 51 in placebo group) completed the study. Evaluation of cessation of smoking was done along with other parameters like measurement of lung capacity, clinical assessment, and laboratory investigations before and after the study.

Results

A significant reduction in smoking as well as in the alveolar Carbon monoxide (p < 0.05) and Carboxyhemoglobin levels (p < 0.05) were observed with the use of Smotect tablets as compared to placebo over a period of 90 days. Significant improvement was also observed in quality of life, energy and stamina levels, and reduction of stress level. Smotect tablets were found to be safe without causing any adverse effects.

Conclusion

Smotect Tablets is an effective and safe remedy for cessation of smoking and reducing other effects related to smoking.

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.

Mid-Regional Pro-Adrenomedullin, Methemoglobin and Carboxyhemoglobin as Prognosis Biomarkers in Critically Ill Patients with COVID-19: An Observational Prospective Study

Mid-regional pro-adrenomedullin (MR-proADM), methemoglobin (MetHb), and carboxyhemoglobin (COHb) levels have been associated with sepsis. In this study, we assessed the role of this potential biomarkers in critically ill COVID-19 patients. Outcomes were mortality and a combined event (mortality, venous or arterial thrombosis, and orotracheal intubation (OTI)) during a 30-day follow-up. A total of 95 consecutive patients were included, 51.6% required OTI, 12.6% patients died, 8.4% developed VTE, and 3.1% developed arterial thrombosis. MetHb and COHb levels were not associated with mortality nor combined event. Higher MR-proADM levels were found in patients with mortality (median of 1.21 [interquartile range-IQR-0.84;2.33] nmol/L vs. 0.76 [IQR 0.60;1.03] nmol/L, p = 0.011) and combined event (median of 0.91 [IQR 0.66;1.39] nmol/L vs. 0.70 [IQR 0.51;0.82] nmol/L, p < 0.001); the positive likelihood ratio (LR+) and negative likelihood ratio (LR−) for mortality were 2.40 and 0.46, respectively. The LR+ and LR− for combined event were 3.16 and 0.63, respectively. MR-proADM ≥1 nmol/L was the optimal cut-off for mortality and combined event prediction. The predictive capacity of MR-proADM showed an area under the ROC curve of 0.73 (95% CI, 0.62–0.81) and 0.72 (95% CI, 0.62–0.81) for mortality and combined event, respectively. In conclusion, elevated on-admission MR-proADM levels were associated with higher risk of 30-day mortality and 30-day poor outcomes in a cohort of critically ill patients with COVID-19.

The History of Carbon Monoxide Intoxication

Intoxication with carbon monoxide in organisms needing oxygen has probably existed on Earth as long as fire and its smoke. What was observed in antiquity and the Middle Ages, and usually ended fatally, was first successfully treated in the last century. Since then, diagnostics and treatments have undergone exciting developments, in particular specific treatments such as hyperbaric oxygen therapy. In this review, different historic aspects of the etiology, diagnosis and treatment of carbon monoxide intoxication are described and discussed.

New strategy for carbon monoxide poisoning diagnosis: Carboxyhemoglobin (COHb) vs Total Blood Carbon Monoxide (TBCO)

Diagnosis of carbon monoxide (CO) poisonings has always been a challenging task due to the susceptibility to alterations of the optical state and degradation of blood samples during sampling, transport and storage, which highly affects the analysis with spectrophotometric methods. Methodological improvements are then required urgently because of increased reports of cases with discrepancies between results of the measured biomarker carboxyhemoglobin (COHb) and reported symptoms. Total blood CO (TBCO) measured chromatographically was thus proposed in a previous study as alternative biomarker to COHb. This approach was investigated in this study by comparing the two biomarkers and assessing the effects of various storage parameters (temperature, preservative, time, tube headspace (HS) volume, initial saturation level, freeze- and thaw- and reopening-cycles) over a period of one month. Results show that while for TBCO, concentrations are relatively stable over the observation period regardless of parameters such as temperature, time and HS volume, for COHb, concentrations are altered significantly during storage. Therefore, the use of TBCO as alternative biomarker for CO poisonings has been proposed, since it provides more valid results and is more stable even under non-optimal storage conditions. Additionally, it can be used to predict COHb in cases where sample degradation hinders optical measurement. Furthermore, a correction formula for COHb and TBCO is provided to be used in laboratories or circumstances where optimal storage or analysis is not possible, to obtain more accurate results.

Determination of hemoglobin mass in humans by measurement of CO uptake during inhalation of a CO-air mixture: a proof of concept study

Measuring hemoglobin mass (Hbmass) using the carbon monoxide (CO) bolus rebreathing method is frequently used in research but has yet to be widely used in the clinical practice. The estimation of an adequate CO bolus may be difficult in patients with unknown Hbmass. In the present pilot study, a progressive inhalation technique for CO that leads to a linear individual adjusted COHb increase was evaluated. Sixteen healthy test subjects participated in the study (preliminary investigation: six; main study: ten). The reliability and validity of the new method were evaluated using multiple measurements of Hbmass with and without a defined blood donation and compared to a CO bolus method. The participants inhaled a CO-air mixture (CO concentration: 1500 ppm) for a specific breathing duration. The CO uptake and COHb change were determined simultaneously. The typical error (reliability) in the repeated measurements was 2.4% (CI ± 4.7). The mean difference between the new method and the bolus method was 34 g (±41; P = 0.026). The measured hemoglobin loss in 490 mL of blood was 74 g (±35), and the calculated hemoglobin loss was 77 g (±4) (mean difference 3 g ± 34; P = 0.820). The new method was reliable and valid in a proof of concept study with healthy subjects. The total amount of CO and as a result the COHb increase is individually adjustable. Future studies in clinical settings are needed to determine if the method could be used in disease-specific pathologies associated with changes in Hbmass.

Carbon monoxide intoxication: What we know

Carbon monoxide (CO) is a toxic, color-, taste- and odorless gas with fatal consequences if undetected. Intoxication caused by CO is frequent possibly leading to a high morbidity and mortality. The disease involves multiple organ systems without a typical clinical presentation. The clinical picture is furthermore unrelated to levels of carboxyhemoglobin - the routine biomarker. Therefore the diagnosis and treatment can be very demanding. This article in detail reviews epidemiology, symptoms, diagnosis and the therapy of this multidisciplinary challenge.

Inhaled cyanide poisoning as a vital sign in a room fire victim

The corpse of a 71-year-old woman was found on the floor of her smoke-filled room. The source of the fire was the mattress of a double bed on which newspapers had apparently been set aflame. The woman's history in conjunction with the finding situation suggested an act of suicide. No signs of soot inhalation or soot swallowing were found at autopsy. Other vital signs were absent. Severe cardiac disease was the most notable pre-existing medical condition. Although the concentration of COHb in heart blood was low (3%), the concentration of cyanide was found to be 4.3mg/l in heart blood and 1.9mg/l in lung tissue. Cyanide was not found in the stomach contents. The BAC (blood alcohol concentration) was zero. Several prescribed drugs could also be demonstrated. The cause of death was deemed to be cyanide poisoning, possibly in conjunction with the pre-existing cardiac disease. The reported case illustrates that a lethal amount of cyanide can be inhaled during a fire even if there is no inhalation or swallowing of soot and no significant increase in the COHb level. In such cases, the demonstration of cyanide assumes significance as a vital sign indicating that the victim was alive when the fire started.

Using expired air carbon monoxide to determine smoking status during pregnancy: preliminary identification of an appropriately sensitive and specific cut-point

BACKGROUND

Measurement of carbon monoxide in expired air samples (ECO) is a non-invasive, cost-effective biochemical marker for smoking. Cut points of 6ppm-10ppm have been established, though appropriate cut-points for pregnant woman have been debated due to metabolic changes. This study assessed whether an ECO cut-point identifying at least 90% of pregnant smokers, and misidentifying fewer than 10% of non-smokers, could be established.

METHODS

Pregnant women (N=167) completed a validated self-report smoking assessment, a urine drug screen for cotinine (UDS), and provided an expired air sample twice during pregnancy.

RESULTS

Half of women reported non-smoking status early (51%) and late (53%) in pregnancy, confirmed by UDS. Using a traditional 8ppm+cut-point for the early pregnancy reading, only 1% of non-smokers were incorrectly identified as smokers, but only 56% of all smokers, and 67% who smoked 5+ cigarettes in the previous 24h, were identified. However, at 4ppm+, only 8% of non-smokers were misclassified as smokers, and 90% of all smokers and 96% who smoked 5+ cigarettes in the previous 24h were identified. False positives were explained by heavy second hand smoke exposure and marijuana use. Results were similar for late pregnancy ECO, with ROC analysis revealing an area under the curve of .95 for early pregnancy, and .94 for late pregnancy readings.

CONCLUSIONS

A lower 4ppm ECO cut-point may be necessary to identify pregnant smokers using expired air samples, and this cut-point appears valid throughout pregnancy. Work is ongoing to validate findings in larger samples, but it appears if an appropriate cut-point is used, ECO is a valid method for determining smoking status in pregnancy.