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.

Secondary polycythemia in chronic obstructive pulmonary disease: prevalence and risk factors.

BACKGROUND: Secondary polycythemia is associated with cigarette smoking and chronic obstructive pulmonary disease (COPD). However, the prevalence of polycythemia in COPD and the contributing risk factors for polycythemia in COPD have not been extensively studied. METHODS: We analyzed the presence of secondary polycythemia in current and former smokers with moderate to very severe COPD at the five-year follow-up visit in the observational COPDGene study. We used logistic regression to evaluate the association of polycythemia with age, sex, race, altitude, current smoking status, spirometry, diffusing capacity for carbon monoxide (DLCO), quantitative chest CT measurements (including emphysema, airway wall thickness, and pulmonary artery to aorta diameter ratio), resting hypoxemia, exercise-induced hypoxemia, and long-term oxygen therapy. RESULTS: In a total of 1928 COPDGene participants with moderate to very severe COPD, secondary polycythemia was found in 97 (9.2%) male and 31 (3.5%) female participants. In a multivariable logistic model, severe resting hypoxemia (OR 3.50, 95% CI 1.41-8.66), impaired DLCO (OR 1.28 for each 10-percent decrease in DLCO % predicted, CI 1.09-1.49), male sex (OR 3.60, CI 2.20-5.90), non-Hispanic white race (OR 3.33, CI 1.71-6.50), current smoking (OR 2.55, CI 1.49-4.38), and enrollment in the Denver clinical center (OR 4.42, CI 2.38-8.21) were associated with higher risk for polycythemia. In addition, continuous (OR 0.13, CI 0.05-0.35) and nocturnal (OR 0.46, CI 0.21-0.97) supplemental oxygen were associated with lower risk for polycythemia. Results were similar after excluding participants with anemia and participants enrolled at the Denver clinical center. CONCLUSIONS: In a large cohort of individuals with moderate to very severe COPD, male sex, current smoking, enrollment at the Denver clinical center, impaired DLCO, and severe hypoxemia were associated with increased risk for secondary polycythemia. Continuous or nocturnal supplemental oxygen use were associated with decreased risk for polycythemia.

Preexisting cardiorespiratory comorbidity does not preclude the success of multidisciplinary rehabilitation in post-COVID-19 patients.

Patients recovering from coronavirus disease 2019 (COVID-19) may not return to a pre-COVID functional status and baseline levels of healthcare needs after discharge from acute care hospitals. Since the long-term outcomes of COVID-19 can be more severe in patients with underlying cardiorespiratory diseases, we aimed at verifying the impact of a preexisting cardiorespiratory comorbidity on multidisciplinary rehabilitation in post-COVID-19 patients. We enrolled 95 consecutive patients referring to the Pulmonary Rehabilitation Unit of Istituti Clinici Scientifici Maugeri Spa SB, IRCCS of Telese Terme, Benevento, Italy after being discharged from the COVID-19 acute care ward and after recovering from acute COVID-19 pneumonia. Forty-nine of them were not suffering from underlying comorbidities, while 46 had a preexisting cardiorespiratory disease. Rehabilitation induced statistically significant improvements in respiratory function, blood gases and the ability to exercise both in patients without any preexisting comorbidities and in those with an underlying cardiorespiratory disease. Response to the rehabilitation cycle tended to be greater in those without preexisting comorbidities, but DLco%-predicted was the only parameter that showed a significant greater improvement when compared to the response in the group of patients with underlying cardiorespiratory comorbidity. This study suggests that multidisciplinary rehabilitation may be useful in post-COVID-19 patients regardless of the presence of preexisting cardiorespiratory comorbidities.

Effectiveness of pirfenidone in idiopathic pulmonary fibrosis according to the autoantibody status: a retrospective cohort study.

BACKGROUND: Pirfenidone is an anti-fibrotic agent shown to slow the progression of idiopathic pulmonary fibrosis (IPF). However, its effectiveness in association with serological autoimmune features in IPF remains unclear. METHODS: We retrospectively reviewed the medical records of patients with IPF treated at a tertiary care hospital in South Korea. The autoantibody status was defined as positive if we detected autoantibodies meeting the serological domain criteria for interstitial pneumonia with autoimmune features or anti-neutrophil cytoplasmic antibodies. RESULTS: We included 142 patients with IPF treated with pirfenidone for over six months (93 were autoantibody-positive and 49 were autoantibody-negative). The mean age was 69.5 ± 7.3 years, and 77.5% of the patients were male. The adjusted mean changes over one year were - 34.4 and - 112.2 mL (p = 0.168) in forced vital capacity (FVC), and - 0.53 and - 0.72 mL/mmHg/min (p = 0.356) in the lungs diffusion capacity for carbon monoxide (DLCO) in the autoantibody-negative and autoantibody-positive groups, respectively. CONCLUSIONS: Reductions in FVC and DLCO were similar in autoantibody-positive and autoantibody-negative patients with IPF treated with pirfenidone. Pirfenidone is effective in attenuating the progression of IPF, irrespective of the autoantibody status.

Changes in nitric oxide, carbon monoxide, hydrogen sulfide and male reproductive hormones in response to chronic restraint stress in rats.

Gasotrasmitters are endogenously synthesized gaseous molecules that are engaged in cellular physiological and pathological processes. Stress influences various physiological aspects of an organism and amends a normal system's functions, including those of the reproductive system. This study aims to investigate the effect of long-term exposure to restraint stress on the male reproductive system as well as the possible impact of stress on the levels of nitric oxide (NO), carbon monoxide (CO) and hydrogen sulfide (H2S), and the expression of their producing-enzymes. In this study, rats were subjected to the restraint condition for 2 h per day and 7 days per week for 8 consecutive weeks. The results revealed decreases in the serum levels of kisspeptin-1(Kiss-1), gonadotropin-releasing hormone (GnRH), luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone and dehydroepiandrosterone sulfate (DHEA-s); however, corticosterone, gonadotropin-inhibitory hormone (GnIH), estradiol (E2) and prolactin levels increased following restraint stress. The mRNA expression levels of NO synthases (NOSs); neuronal NOS (nNOS), inducible NOS (iNOS) and H2S synthases; cystathionine-γ-lyase- (CSE), 3-mercaptopyruvate-sulfurtransferase- (3MST) and CO-producing enzyme; heme oxygenase-2 (HO-2) were upregulated in the hypothalamus of restraint rats. Testicular mRNA expression levels of endothelial NOS (eNOS), nNOS, HO-1 and HO-2 were upregulated whereas cystathionine ß-synthase (CBS), CSE and 3MST expression levels were downregulated following restraint stress. Concentrations of NO increased in the testes but decreased in the semen of restraint rats. On the contrary, CO levels were reduced in the testes while they were elevated in the semen, whereas H2S concentrations decreased in both testes and semen of restraint rats. Concentrations of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPX), as well as total antioxidant capacity (TAC) rose in the testes, while they declined in the semen of the restraint group. Restraint stress decreases the levels of reactive oxygen species (ROS) and malondialdehyde (MDA) in the testes while increasing them in the semen. Collectively, restraint stress negatively impacts male reproductive functions and modulates gasotransmitters producing-enzymes expression in the hypothalamus and testes.

¿Mienten los pacientes con EPOC sobre su hábito tabáquico? / Do COPD patients lie about their smoking habit?

OBJETIVO: Determinar la tasa de decepción o concordancia entre la respuesta de los pacientes con enfermedad pulmonar obstructiva crónica (EPOC) sobre su hábito tabáquico y la medición del mismo por cooximetría en una consulta monográfica EPOC. DISEÑO: Estudio observacional prospectivo para determinar la concordancia entre los valores de cooximetría y la respuesta a entrevista clínica sobre hábito tabáquico. EMPLAZAMIENTO: Consulta monográfica de EPOC, Neumología, Sevilla. PARTICIPANTES: Pacientes con diagnóstico confirmado de EPOC en cualquier grado. INTERVENCIONES: Entrevista clínica y medición de monóxido de carbono mediante cooximetría. MEDICIONES PRINCIPALES: Valores de cooximetría, respuestas sobre hábito tabáquico, variables sociodemográficas. RESULTADOS: Se incluyó un total de 169 pacientes (n: 169) de los cuales, 107 presentaron valores menores o iguales 6 ppm frente a 62 con valores mayores a 6 ppm, determinando una prevalencia de tabaquismo activo del 36,7%. La tasa de decepción fue del 19,5% del total de la muestra (24,3% de entre todos los que afirmaban no fumar), con una kappa de Cohen de 0,48 y p < 0,000. El 40% de los pacientes confesó no haber dicho la verdad. No se encontró ninguna relación de este dato con la edad, el consumo acumulado de tabaco ni el FEV1. Se halló una relación significativa con el sexo (tasa de decepción: 31,8% en las mujeres vs. 15,2% en los hombres, p 0,017). CONCLUSIONES: A pesar de nuestros intentos para que los pacientes dejen de fumar, la tasa de decepción en nuestra consulta fue considerable, mayor entre las mujeres, exfumadores recientes o en proceso de abandono, por lo que sería fundamental incorporar medidas objetivas como el cooxímetro en el abordaje de este tipo de pacientes

OBJECTIVE: To determine the deception rate or concordance between the interview on smoking and cooximetry in COPD patients from a monographic consultation. DESIGN: Prospective observational study to evaluate the concordance between the values of cooximetry and the response to a clinical interview on smoking. SETTING: COPD monographic consultation, Pneumology, Seville. PARTICIPANTS: Patients with a confirmed diagnosis of COPD in any degree. INTERVENTIONS: Clinical interview and measurement of carbon monoxide by cooximetry. MAIN MEASUREMENTS: Cooximetry values, responses on smoking, sociodemographic variables. RESULTS: n: 169. 107 patients presented values less than or equal to 6 ppm compared to 62 with values greater than 6 ppm, determining a prevalence of active smoking of 36.7%. The deception rate was 19.5% of the total sample (24.3% of all those who claimed not to smoke), with a Cohen kappa of 0.48 and p < 0.000. 40% of patients confessed not having told the truth. No relationship of this data was found with age, accumulated tobacco consumption or FEV1. A significant relationship with sex was found (deception rate: 31.8% in women vs. 15.2% in men, p 0.017). CONCLUSIONS: In spite of our attempts to make patients stop smoking, a considerable deception rate was found in our consultation; higher among women, recent ex-smokers or in the process of abandonment, so it would be essential to incorporate objective measures such as the cooximeter in the approach of this type of patient

Reproducibility of the CO rebreathing technique with a lower CO dose and a shorter rebreathing duration at sea level and at 2320 m of altitude.

Total hemoglobin mass (Hbmass) is routinely assessed in studies by the carbon monoxide (CO) rebreathing. Its clinical application is often hindered due to the consequent rise in carboxyhemoglobin (%HbCO) and the concern of CO toxicity. We tested the reproducibility of the CO rebreathing with a CO dose of 0.5 mL/kg body mass (CO0.5) compared to 1.5 mL/kg (CO1.5) and when shortening the CO rebreathing protocol. Therefore, CO rebreathing was performed 1×/day in eight healthy individuals on four consecutive days. On each day, either CO0.5 (CO0.5-1 and CO0.5-2) or CO1.5 (CO1.5-1 and CO1.5-2) was administered. Venous blood samples to determine %HbCO and quantify Hbmass were obtained prior to, and at 6 (T6), 8 (T8) and 10 min (T10) of CO rebreathing. This protocol was tested at sea level and at 2320 m to investigate the altitude-related measurement error. At sea level, the mean difference (95% limits of agreement) in Hbmass between CO0.5-1 and CO0.5-2 was 26 g (-26; 79 g) and between CO1.5-1 and CO1.5-2, it was 17 g (-18; 52 g). The respective typical error (TE) corresponded to 2.4% (CO0.5) and 1.5% (CO1.5), while it was 6.5% and 3.0% at 2320 m. With CO0.5, shortening the CO rebreathing resulted in a TE for Hbmass of 4.4% (T8 vs. T10) and 14.1% (T6 vs T10) and with CO1.5, TE was 1.6% and 5.8%. In conclusion, the CO dose and rebreathing time for the CO rebreathing procedure can be decreased at the cost of a measurement error ranging from 1.5-14.1%.

Cardiovascular effects of increasing dosages of norepinephrine in healthy isoflurane-anesthetized New Zealand White rabbits.

OBJECTIVE: To characterize the cardiovascular effects of increasing dosages of norepinephrine (NE) in healthy isoflurane-anesthetized rabbits. STUDY DESIGN: Prospective experimental study. ANIMALS: A total of nine female ovariohysterectomized New Zealand White rabbits weighing 3.4 ± 0.2 kg (mean ± standard deviation). METHODS: Rabbits were premedicated intramuscularly with buprenorphine (0.05 mg kg-1) and midazolam (0.5 mg kg-1). Anesthesia was induced with intravenous propofol and maintained with a 1.1 × minimum alveolar concentration of isoflurane for this species to induce hypotension. Rabbits were administered NE infusions at three doses: low, 0.1 µg kg-1 minute-1; medium, 0.5 µg kg-1 minute-1; and high doses, 1 µg kg-1 minute-1 for 10 minutes each in that order. Cardiovascular variables including heart rate (HR), cardiac output (CO) by lithium dilution technique and systolic (SAP), mean (MAP) and diastolic (DAP) invasive arterial blood pressures measured in the auricular artery were recorded at baseline, 10 minutes after the start of the infusion of each NE treatment and 10 minutes after NE was discontinued. A linear mixed model and a type III anova with Tukey's post hoc comparison was performed (p < 0.05). RESULTS: Significant increases in SAP (28% and 90%), MAP (27% and 90%) and DAP (33% and 97%) were measured with medium and high dose treatments, respectively (p < 0.001), with no changes in CO. HR decreased and stroke volume increased significantly with high dose treatment (by 17% and 15%, respectively; p < 0.05). No arrhythmias were noticed with NE treatments. CONCLUSIONS AND CLINICAL RELEVANCE: The infusion of NE at 0.5-1.0 µg kg-1 minute-1 is a potentially effective treatment for hypotension in healthy isoflurane-anesthetized New Zealand White rabbits.

Heme Catabolism and Bilirubin Production in Readmitted Jaundiced Newborns.

We measured end-tidal CO levels in 50 jaundiced newborns readmitted for phototherapy at age 54-244 hours. The median end-tidal CO level was 1.55 ppm, suggesting that hemolysis is not the primary contributor to the hyperbilirubinemia in many readmitted newborns.

Efficacy, safety, and tolerability of combined pirfenidone and N-acetylcysteine therapy: a systematic review and meta-analysis.

BACKGROUND: While antifibrotic drugs significantly decrease lung function decline in idiopathic pulmonary fibrosis (IPF), there is still an unmet need to halt disease progression. Antioxidative therapy with N-acetylcysteine (NAC) is considered a potential additional therapy that can be combined with antifibrotics in some patients in clinical practice. However, data on the efficacy, tolerability, and safety of this combination are scarce. We performed a systematic review and meta-analysis to appraise the safety, tolerability, and efficacy of the combination compared to treatment with pirfenidone alone. METHODS: We systematically reviewed all the published studies with combined pirfenidone (PFD) and NAC (PFD + NAC) treatment in IPF patients. The primary outcomes referred to decline in pulmonary function tests (PFTs) and the rates of IPF patients with side effects. RESULTS: In the meta-analysis, 6 studies with 319 total IPF patients were included. The PFD + NAC group was comparable to the PFD alone group in terms of the predicted forced vital capacity (FVC%) and predicted diffusion capacity for carbon monoxide (DLco%) from treatment start to week 24. Side effects and treatment discontinuation rates were also comparable in both groups. CONCLUSION: This systematic review and meta-analysis suggests that combination with NAC does not alter the efficacy, safety, or tolerability of PFD in comparison to PFD alone in IPF patients.

Changes in CO-oximetry values and pulse oximetry in isoflurane-anesthetized dogs with and without nitrous oxide.

Concentrations of 64% to 70% nitrous oxide (N2O) provide intra-operative analgesia. Clinically, pulse oximeter estimation (SpO2) of oxygen (O2) hemoglobin saturation (SaO2) was observed to decrease with N2O. Absorption atelectasis from breathing O2 was thought to decrease arterial partial pressure of O2 (PaO2) below 70 mmHg and reduce SaO2 and SpO2 when N2O was used. Administering N2O from the beginning of the anesthesia might prevent atelectasis development and low PaO2. The study was done in 2 parts (P < 0.05). In Part 1, isoflurane-anesthetized dogs undergoing ovariohysterectomy (n = 15 each group) breathed N2O from anesthesia start (N2Oearly) or 1 hour later (N2Olate). SpO2, CO-oximetry values, and PaO2 were compared to dogs breathing O2 throughout anesthesia (control). Timing of N2O introduction did not affect PaO2 (lowest = 94 mmHg), SaO2, or SpO2. With N2O, the lowest SpO2 value was 91% and corresponded to a PaO2 of 151 mmHg. Carboxyhemoglobin increased (highest = 2.7%) and SaO2 decreased with N2O (lowest = 96.7%). In Part 2, to replicate findings, 10 isoflurane-anesthetized dogs breathed N2O, then O2. With N2O, SaO2 did not decrease, but carboxyhemoglobin increased and returned to baseline once N2O was discontinued. The dog with the highest carboxyhemoglobin (2%) had an SaO2 of 96.8% (PaO2 = 93 mmHg). Carboxyhemoglobin and SaO2 changes were not clinically significant. Pulse oximetry did not reliably estimate SaO2 but N2O was not always a factor.

Des concentrations de 64 % à 70 % d'oxyde nitreux (N2O) apporte une analgésie intra-opératoire. Cliniquement, il a été noté que l'estimation par oxymétrie de pouls (SpO2) de la saturation en oxygène (O2) de l'hémoglobine (SaO2) diminuait avec le N2O. Une atélectasie d'absorption due à la respiration d'O2 était suspectée diminuer la pression artérielle partielle en O2 (PaO2) sous la valeur de 70 mmHg et réduire SaO2 et SpO2 lorsque le N2O était utilisé. L'administration de N2O depuis le début de l'anesthésie pourrait prévenir le développement d'atélectasie et une faible PaO2.La présente étude a été réalisée en deux parties (P < 0,05). Dans la Partie 1, des chiennes anesthésiées à l'isoflurane soumis à une ovariohystérectomie (n = 15 dans chaque groupe) ont respiré du N2O depuis le début de l'anesthésie (N2Oearly) ou 1 heure plus tard (N2Olate). Les valeurs de SpO2, d'oxymétrie de CO, et de PaO2 furent comparées à celles de chiens respirant O2 tout au long de l'anesthésie (témoin). Le moment d'introduction du N2O n'a pas affecté PaO2 (plus basse = 94 mmHg), SaO2 ou SpO2. Avec le N2O, la plus basse valeur de SpO2 était 91 % et correspondait à une PaO2 de 151 mmHg. La carboxyhémoglobine augmenta (plus élevée = 2,7 %) et SaO2 diminua avec le N2O (plus basse = 96,7 %).Dans la Partie 2, pour reproduire les résultats, 10 chiens anesthésiés avec de l'isoflurane ont respiré du N2O, puis O2. Avec le N2O, SaO2 n'a pas augmenté, mais la carboxyhémoglobine augmenta et retourna à la valeur de base une fois que le N2O fut arrêté. Le chien avec la valeur de carboxyhémoglobine la plus élevée (2 %) avait une SaO2 de 96,8 % (PaO2 = 93 mmHg). Les changements de valeurs de carboxyhémoglobine et de SaO2 n'étaient pas cliniquement significatifs. L'oxymétrie de pouls n'estimait pas de manière fiable SaO2 mais le N2O n'était pas toujours un facteur.(Traduit par Docteur Serge Messier).

Physiological predictors of survival in patients with sarcoidosis-associated pulmonary hypertension: results from an international registry.

INTRODUCTION: Sarcoidosis-associated pulmonary hypertension (SAPH) is associated with reduced survival in single-centre studies. The international Registry for SAPH (ReSAPH) with long-term follow-up was established to enrich our knowledge of this complication of sarcoidosis. This analysis aims to elucidate factors associated with reduced transplant-free survival in SAPH patients. METHODS: ReSAPH contains prospectively collected outcomes of SAPH patients since the time of registry enrolment. Information analysed includes right heart catheterisation data, pulmonary function testing, chest radiography, Scadding stage and 6-min walk distance (6MWD), among others. Cox regression models were used to identify independent predictors of transplant-free survival. RESULTS: Data from 215 patients followed for a mean±sd 2.5±1.9 years were available for analysis. In the 159 precapillary patients, the Kaplan-Meier-adjusted 1-, 3- and 5-year transplant-free survival was 89.2%, 71.7% and 62.0%, respectively. Kaplan-Meier-adjusted 1-, 3- and 5-year transplant-free survival in the incident group was 83.5%, 70.3% and 58.3%, respectively, and in the prevalent group was 94.7%, 72.2% and 66.3%, respectively. Patients with reduced diffusing capacity of the lung for carbon monoxide (D LCO) (<35% predicted) and 6MWD <300 m in the precapillary cohort had significantly worse transplant-free survival. Reduced 6MWD and preserved forced expiratory volume (FEV1)/forced vital capacity (FVC) ratio were identified as independent risk factors for reduced transplant-free survival in the precapillary cohort. CONCLUSION: Reduced D LCO (<35% pred) and 6MWD (<300 m) at the time of registry enrolment were associated with reduced transplant-free survival in the overall precapillary cohort. Preserved FEV1/FVC ratio was identified as an independent risk factor for worsened outcomes.

Effects of adopting the Global Lung Function Initiative 2017 reference equations on the interpretation of carbon monoxide transfer factor.

The recently published Global Lung Function Initiative (GLI) carbon monoxide transfer factor (T LCO) reference equations provide an opportunity to adopt a current, all-age, widely applicable reference set. The aim of this study was to document the effect of changing to GLI from commonly utilised reference equations on the interpretation of T LCO results.33 863 T LCO results (48% female, 88% Caucasian, n=930 aged <18 years) from clinical pulmonary function laboratories within three Australian teaching hospitals were analysed. The lower limit of normal (LLN) and proportion of patients with a T LCO below this value were calculated using GLI and other commonly used reference equations.The average T LCO LLN for GLI was similar or lower than the other equations, with the largest difference seen for Crapo equations (median: -1.25, IQR: -1.64, -0.86 mmol·min-1·kPa-1). These differences resulted in altered rates of reduced T LCO for GLI particularly for adults (+1.9% versus Miller to -27.6% versus Crapo), more so than for children (-0.8% versus Kim to -14.2% versus Cotes). For adults, the highest raw agreement for GLI was with Miller equations (94.7%), while for children it was with Kim equations (98.1%). Results were reclassified from abnormal to normal more frequently for younger adults, and for adult females, particularly when moving from Roca to GLI equations (30% of females versus 16% of males).The adoption of GLI T LCO reference equations in adults will result in altered interpretation depending on the equations previously used and to a greater extent in adult females. The effect on interpretation in children is less significant.

Factors Contributing to CO Uptake and Elimination in the Body: A Critical Review.

BACKGROUND: Carbon monoxide (CO) poisoning is an important public health issue around the world. Research indicates that many factors may be related to the rate of CO uptake and elimination in the human body. However, some factors related to CO uptake and elimination are considered controversial. Relatively little attention has been devoted to review and synthesis of factors affecting CO uptake and elimination. PURPOSE: This paper provides a critical scoping review of the factors and divides them into four aspects, including environmental, demographic, physiological and treatment factors. METHODS: We searched the scientific databases for research that has proposed a mathematical equation as a synthesis of quantities related to CO poisoning, CO elimination, CO uptake, CO half-life, CO uptake and elimination and their relationships. After excluding the studies that did not meet the study criteria, there were 39 studies included in the review and the search was completed before 16 December 2019. RESULTS AND CONCLUSION: This review discusses most of the factors that impact the rate of CO uptake and elimination. Several factors may be related to CO uptake and elimination, such as CO concentration, the duration of exposure to CO, age, sex, exercise, minute ventilation, alveolar ventilation, total haemoglobin mass and different treatments for CO poisoning. Although some potential factors were not included in the review, the findings are useful by presenting an overview for discussing factors affecting CO uptake and elimination and provide a starting point for further study regarding strategies for CO poisoning and the environmental standard of CO.

Four-type of Masks and its Effectiveness Based on Reduced Level of Expiratory Carbon-monoxide.

INTRODUCTION: Carbon-monoxide (CO) is a major component of motor-vehicles related air pollution. Motor-vehicles emissions are a major source of air pollution in urban areas and give significant adverse effects on human life. AIM: This study aimed to assess the change of expiratory carbon-monoxide levels after using four-type of masks in people around Universitas Sumatera Utara. METHODS: This was an experimental study with a consecutive sampling technique involved 100 non-smoker subjects. They were divided into four groups based on masks given: fabric, surgical, carbon, and an N95 mask. Expiratory CO was measured by a smokerlyzer device. Data were analyzed using SPSS software with Wilcoxon and Kruskal Wallis Test. RESULTS: There was a significant change of carbon-monoxide mean level after using the mask for 8 hours in a surgical mask, N95 mask, and carbon mask (p-value: 0.002; 0.000; 0.000). After analyzed using Kruskal Wallis Test, there was a significant difference in the change of mean of pre and post wearing mask (ΔCO) among four-type of masks with p-value < 0.001. Post Hoc Analysis showed the significant difference was in the comparison between N95 mask vs Fabric Mask and Carbon Mask vs Fabric Mask (p-value: 0.002; 0.021). CONCLUSION: All three type of masks such as surgical mask, N95 mask, and carbon mask was effective to reduce CO levels from air pollution with the most significant was N95 and carbon mask. Fabric mask has the poorest protection from CO levels.

Comparison of Different Analytical Methods for the Determination of Carbon Monoxide in Postmortem Blood.

The determination of carbon monoxide (CO) and carboxyhemoglobin (COHb) is of utmost importance in forensic toxicology to determine the cause of death in cases of CO poisoning, fire, and explosions. To this end, reliable and updated analytical methods are required. In this paper, four different methods for the determination of carbon monoxide in postmortem blood samples were compared: (i) the spectrophotometric determination of COHb applying the method proposed by Rodkey and modified by Beutler-West, (ii) the spectrophotometric determination of CO using a micro-diffusion-based method, (iii) the determination of CO by gas chromatography coupled to a TCD detector, and (iv) the determination of COHb by blood gas analysis. Three postmortem blood samples were analyzed with all methods, and the results were comparable. The applied methodologies showed different features depending on the sensitivity, sample preparation, and volume. The HS-GC/TCD method in our hand was the most appropriate, on postmortem samples, and versatile to apply. Unfortunately, only a limited number of postmortem blood samples were available for this study due to the rarity of that kind of intoxication in our jurisdiction.

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.