Breath analysis to detect recent exposure to carbon monoxide

Non-invasive detection of renal disease biomarkers through breath analysis

Breath biomarkers are substances found in exhaled breath that can be used for non-invasive diagnosis and monitoring of medical conditions, including kidney disease. Detection techniques include mass spectrometry (MS), gas chromatography (GC), and electrochemical sensors. Biosensors, such as GC-MS or electronic nose (e-nose) devices, can be used to detect volatile organic compounds (VOCs) in exhaled breath associated with metabolic changes in the body, including the kidneys. E-nose devices could provide an early indication of potential kidney problems through the detection of VOCs associated with kidney dysfunction. This review discusses the sources of breath biomarkers for monitoring renal disease during dialysis and different biosensor approaches for detecting exhaled breath biomarkers. The future of using various types of biosensor-based real-time breathing diagnosis for renal failure is also discussed.

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

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

Effects of different fresh gas flows on carboxyhemoglobin levels: non-invasive carbon monoxide monitoring: A randomized clinical trial

OBJECTIVES

To observe the effect of different fresh gas flows (FGF) on carboxyhemoglobin (COHb) levels non-invasively and continuously and to determine the contribution of the smoking status to intraoperative carbon monoxide (CO) accumulation and respiratory complications.

METHODS

A total of 64 patients were included in the study. Carboxyhemoglobin level was monitored non-invasively from the fingertip. Patients were divided into 2 according to the FGF as low-flow anesthesia (LFA; Group L) and high flow anesthesia (Group H). Each group was divided again into 2 groups as smokers and non-smokers. Carboxyhemoglobin and and the respiratory complications that occurred in the post-anesthesia care unit were recorded.

RESULTS

The mean COHb values were significantly higher in Group L between 30th and 210th minutes. Furthermore, in Group L, intraoperative COHb levels were significantly higher in smokers compared to non-smokers in all periods. In group H, no difference was observed between smokers and non-smokers in terms of COHb levels after 60 minutes and also preoperative COHb levels of the patients developed respiratory complication was higher.

CONCLUSION

If the CO₂ absorbent is properly preserved in patients who are administered LFA, there will be no risk of CO accumulation even in chronic smokers.ClinicalTrials.gov REG. No.: NCT04832256.

Tips for avoiding common mistakes in out-of-hospital diagnosis of carbon monoxide poisoning

Acute carbon monoxide poisoning is the leading cause of intoxication from exogenous substances in the world. It is also a major cause of morbidity and mortality due to poisoning in the USA. In the USA, it determines to 50,000 visits per year in emergency departments with a mortality ranging from 1 to 3%. Although prevalence and incidence data reveal the large impact of carbon monoxide poisoning on public health, some studies have shown that errors in its diagnosis have a high incidence (30%) and that awareness campaigns have allowed the reduction of the same to 5%. In addition, many diagnostic and/or therapeutic errors were found both in small first aid situations and in the context of rescue units belonging to prestigious hospitals. To formulate a diagnosis, the collection of clues from the environment in which the patient is found is essential. Especially when the routine use of environmental gas detectors or handheld CO-oximeters is not possible, the emergency doctor, in addition to concentrating on the clinical presentation of the case, will have to give a quick overview of the patient and his environment. In addition to age, sex, and already known comorbidities, it is not irrelevant to evaluate socio-economic and cultural characteristics, hygiene conditions, habits, etc.The purpose of this study is to provide useful information to the doctor who comes first to the site of intoxication to reduce diagnostic and therapeutic errors in the pre- and intra-hospital phase as much as possible.

Effect of cigarette smoking on smoking biomarkers, blood pressure and blood lipid levels among Sri Lankan male smokers

Study purpose

The aim of this study was to determine the fractional exhaled nitric oxide (FeNO) levels, exhaled breath carbon monoxide (eCO) levels, blood pressure, blood lipid levels between smokers and non-smokers and to determine the association of smoking intensity with the above parameters.

Methods

This descriptive study was conducted in selected periurban areas of the Colombo District, Sri Lanka. Adult male current tobacco smokers (n=360), aged between 21 and 60 years were studied and compared with anthropometrically matched male non-smokers (n=180). Data were collected by interviewer-administered questionnaire, clinical assessment and measurement of FeNO by FENO monitor and eCO bySmokerlyser.

Results

Smokers had significantly lower mean FeNO levels and higher mean eCO values compared with non-smokers. Presentation of palpitations was higher among the smokers and a significantly positive correlation was identified between palpitations and eCO levels. There was a significantly positive correlation between the systolic blood pressure of smokers with the duration of smoking (DS), Brinkman Index (BI), Body Mass Index (BMI) and there was a significantly negative correlation with FeNO levels. The mean arterial pressure was positively correlated with the DS, BI and BMI. There was a significantly negative correlation between FeNO and the number of cigarettes smoked per day, DS and BI of smokers. Significantly higher total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), very LDL-C, TC: HDL ratio and low high density lipoprotein cholesterol (HDL-C) level was observed among smokers compared with the non-smokers.

Conclusions

Tobacco smoking was found to impact blood pressure and serum lipid levels thus enhancing the cardiovascular risk among smokers. The levels of eCO and FeNO are useful biomarkers for determining the intensity of smoking. The results indicate the necessity for urgent measures to stop cigarette smoking in Sri Lanka.

Impairments of facial detection in tobacco use disorder: baseline data and impact of smoking duration

Objective:

Chronic tobacco consumption, classified as tobacco use disorder (TUD), has been associated with a variety of health problems. Investigations of face processing in TUD are hampered by lack of evidence. Here, we evaluated facial detection in TUD and assessed test-retest reliability for a facial detection task.

Methods:

Participants were instructed to detect the orientation (either left or right) of a face when it was presented with a face/non-face pair on the monitor screen, using Bayesian entropy estimation. Bland-Altman analysis and intraclass correlation coefficients were used to test the reliability of the task. The general linear model and Bayesian statistics were then used to evaluate differences between TUD (n=48) and healthy controls (n=34).

Results:

The reliability of the task was high for the 96 stimuli presentations. Slower reaction times (p < 0.001) and lower discrimination index (p < 0.001) were observed in the TUD group than for healthy controls. Mediation analysis indicated direct effects of smoking duration on reaction time (p < 0.001) and discrimination index (p < 0.001).

Conclusions:

Overall, we observed high reliability of this task and reduction of facial detection in tobacco use disorder. We conclude our findings are significant for public health initiatives and call for follow-up studies.

Nicotine Dependence among Adolescents Single and Dual Cigarette Users

The prevalence of concurrent use of combustible and electronic cigarettes (dual-use) is on the rise among Malaysian adolescents. This study compares nicotine dependence among exclusive cigarette users, e-cigarette users, and dual adolescent users. A total of 227 adolescent smokers completed a self-administrated questionnaire with items based on Hooked on Nicotine Checklist (HONC) incorporated. Endorsement of at least one HONC item indicates nicotine dependence. Exhaled carbon monoxide readings and salivary cotinine data were also collected. Over half (52.9%) of the participants were exclusive e-cigarette users (EC). The prevalence of exclusive conventional cigarette smokers (CC) and dual users was 11.9% and 35.2%, respectively. Adolescents who have mothers with secondary school education were more likely to become addicted to nicotine (Adjusted Odd Ratio (aOR) = 2.72; 95% CI = 1.17–6.32). Adolescents’ “mother’s education” level predicted nicotine dependence. This highlighted the need to target families within the identified demography with a more supportive anti-tobacco program.

Impact of breath sampling on exhaled carbon monoxide

The influence of breath sampling on exhaled carbon monoxide (eCO) and related pulmonary gas exchange parameters is investigated in a study with 32 healthy non-smokers. Mid-infrared tunable diode laser absorption spectroscopy and well-controlled online sampling is used to precisely measure mouth- and nose-exhaled CO expirograms at exhalation flow rates (EFRs) of 250, 120 and 60 ml s^-1, and for 10 s of breath-holding followed by exhalation at 120 ml s^-1. A trumpet model with axial diffusion is employed to fit simulated exhalation profiles to the experimental expirograms, which provides equilibrium airway and alveolar CO concentrations and the average lung diffusing capacity in addition to end-tidal concentrations. For all breathing maneuvers, excellent agreement is found between mouth- and nose-exhaled end-tidal CO (ETCO), and the individual values for ETCO and alveolar diffusing capacity are consistent across maneuvers. The eCO parameters clearly show a dependence on EFR, where the lung diffusing capacity increases with EFR, while ETCO slightly decreases. End-tidal CO is largely independent of ambient air CO and alveolar diffusing capacity. While airway CO is slightly higher than, and correlates strongly with, ambient air CO, and there is a weak correlation with ETCO, the results point to negligible endogenous airway CO production in healthy subjects. An EFR of around 120 ml s^-1 can be recommended for clinical eCO measurements. The employed method provides means to measure variations in endogenous CO, which can improve the interpretation of exhaled CO concentrations and the diagnostic value of eCO tests in clinical studies. Clinical trial registration number: 2017/306-31.

Comparison of indoor air quality during sleep in smokers and non-smokers' bedrooms: A preliminary study

People spend one third of their life sleeping, but the bedroom, as a specific micro-environment, is often neglected when assessing human exposure to air pollutants. However, exposure during sleep may be significant in the long-term to the integrated individual exposure. This study aimed to assess the exposure during sleep, focusing on a multi-pollutant approach (comfort parameters, carbon dioxide - CO₂, carbon monoxide - CO, formaldehyde (CH₂O), total volatile organic compounds (VOCs), particulate matter - PM_2.5 and PM₁₀ - and ultrafine particles, particle number concentrations - PNC - and lung deposited surface area - LDSA). For that, the air quality during sleep (in real conditions) was monitored using real-time devices in 12 bedrooms of urban (Lisbon and Vila Franca de Xira) and rural (Ponte de Sor) areas of Portugal for one night. Volunteers were smokers and non-smokers. Considering the Portuguese legislation for indoor air quality (IAQ), 67% of the bedrooms registered CO₂ levels above the limit value, while CH₂O, VOC, PM₁₀ and PM_2.5 thresholds were exceeded in 30, 100, 36, and 45% of cases, respectively. Regarding ultrafine parameters, LDSA and PNC ranged from 7.3 to 95.2 μm²/cm³ and from 0.6 to 4.8 × 10³/cm³, respectively. Even with no smoking indoors, smokers' bedrooms were found to have significant higher levels of CO, CH₂O, PM_2.5, PM₁₀ and LDSA than non-smokers' bedrooms, showing the effect of thirdhand smoke, exhalation of pollutants after smoking and infiltration on the degradation of the air quality in the bedroom. A recent new model of real-time monitor was also used for a wide set of IAQ parameters. Its performance to measure PM_2.5 and CO₂ was assessed, showing its applicability in real conditions. Although often neglected, these micro-environments should be considered in the integrated individual exposure to air pollutants and further studied. MAIN FINDINGS OF THE WORK: Several pollutants (CO₂, PM, VOCs and CH₂O) exceeded the guidelines during sleep; smokers are exposed to higher levels of CO, CH₂O, PM, and LDSA than non-smokers while sleeping.

Air pollution may affect the assessment of smoking habits by exhaled carbon monoxide measurements

BACKGROUND

While European air quality policies reduce ambient carbon monoxide (CO) concentrations in general, there are still areas affected by high environmental CO exposure from transportation, industry and burning low-quality fossil fuels. We investigated, how these CO amounts might influence exhaled CO measurements used to monitor the smoking status of healthy subjects.

METHODS

A cross-sectional study of healthy adults living in areas of high air pollution (N = 742) and low air pollution (N = 197) in Poland. They completed a survey regarding their smoking habits and underwent necessary body measurements including exhaled CO concentration levels.

RESULTS

Ambient CO levels were much higher in highly pollutes cities. Also exhaled CO levels in subjects from high pollution areas were significantly higher, independent of subject smoking status (8.25 ppm vs. 3.26 ppm). Smokers exhaled more CO than non-smokers. Although the duration of smoking did not affect the CO levels, they were proportional to the number of cigarettes smoked during the day, especially for higher amounts of cigarettes and in unpolluted areas. It was possible to differentiate active from passive smokers in all areas, but the difference for passive smokers vs. non-smokers was significant only in low pollution city inhabitants.

CONCLUSIONS

Exhaled CO levels were confirmed to be a good indicator of smoking status and smoking pattern in healthy subjects. However, high environmental CO levels both increase baseline exhaled CO concentrations in non-smokers affecting their discrimination from passive smokers, and obscure categorizing cigarette consumption in heavy smokers. These findings add important evidence on both understanding of exhaled CO monitoring results and a significance of environmental CO exposure in areas with high pollution.

The implications of high carbon monoxide levels in early pregnancy for neonatal outcomes

OBJECTIVES

The aim of this study was to examine the implications of increased maternal Breath Carbon Monoxide (BCO) levels at the first antenatal visit for subsequent birthweight (BW) and neonatal outcomes.

STUDY DESIGN

Secondary analysis of a prospective, observational study. Pregnant women aged ≥18years who understood English were recruited (n=250). However, only women who delivered a normally formed baby weighing ≥500g were analysed (n=234). At the first antenatal visit, a research questionnaire was completed and a BCO test was performed. Obstetric and neonatal data computerised by midwives at the first antenatal visit and updated after delivery were also analysed.

RESULTS

Results from the receiver operating characteristic (ROC) curve indicated the highest combined sensitivity and specificity for smoking was observed at a BCO cut-off level of 3ppm (sensitivity 85%, specificity 90%). Of the 234 women, 53 (22.6%) had a BCO ≥3ppm but only 36 (15.4%) disclosed smoking to the midwife on routine questioning. A further 23 (9.8%) were classified as non-disclosers based on a research questionnaire and/or a BCO measurement ≥3ppm. No relationship was found between the self-reported number of cigarettes daily in early pregnancy and BW (r=0.05, p=0.78). However, an inverse relationship was found between maternal BCO levels and BW (r=-0.31, p<0.001). BCO levels ≥3ppm in early pregnancy were associated with an increased risk of emergency caesarean section, low birth weight, BW <25th centile, fetal distress and having two or more adverse pregnancy events (all p<0.05). Smoking non-disclosers had babies with decreased BWs (-400.1g, 95% CI 141.1-659.0g, p<0.001), and higher rates of BW <25th centile (56.5% versus 25.3%, p<0.001), small-for-gestational-age (21.7% versus 9.1%, p<0.001) and fetal distress (39.1% versus 16.0%, p<0.01) compared to non-smokers Non-disclosers at the first antenatal visit also had a 22% higher rate of having two or more adverse pregnancy events (p<0.05).

CONCLUSION

The results showed that an increased BCO level was associated with a lower BW and increased risk of adverse pregnancy and neonatal outcomes. This strengthens the case for universal BCO screening at the first antenatal visit. A high BCO reading should be an indication for referral to stop smoking services referral and close fetal surveillance.

Clinical utility of exhaled carbon monoxide in assessing preoperative smoking status and risks of postoperative morbidity after esophagectomy

Whereas smoking constitutes a significant risk factor for postesophagectomy morbidity, there is no reliable method to assess the smoking status of patients prior to the procedure. Since exhaled carbon monoxide (CO) is an indicator of recent smoking, this paper hypothesizes that this is a useful parameter in assessing current smoking status and may help predict morbidity following esophagectomy. Sixty-nine patients, who had undergone elective three-incision esophagectomy with two- or three-field lymphadenectomy for esophageal cancer, were prospectively studied between February 2015 and September 2017. At surgical admission, they were asked about their smoking history, their exhaled CO levels were evaluated, and they were grouped into three based on their CO levels. These were 0 parts per million (ppm), >0 and <7 ppm, and ≥7 ppm. Their postoperative morbidity was also assessed. Approximately 13.5% of the patients showed high levels of exhaled CO ≥ 7 ppm, despite preoperatively reporting smoking cessation for over a month. Morbidities of the Clavien-Dindo classification (CDc) ≥ II increased as exhaled CO levels increased and severe morbidity of CDc ≥ IIIb frequently was observed in patients with exhaled CO levels ≥7 ppm. The logistic regression analysis showed that exhaled CO level ≥7 ppm was an independent risk factor for severe postesophagectomy morbidity. Overall, the results of this study suggest that exhaled CO levels may be useful in estimating current smoking status and that it may also help give an estimation of the risk of postesophagectomy morbidity.

A prospective, observational study investigating the use of carbon monoxide screening to identify maternal smoking in a large university hospital in Ireland

OBJECTIVES

This study evaluated breath carbon monoxide (BCO) testing in identifying maternal smokers as well as the difference between disclosers and non-disclosers of smoking status. We also investigated if other extrinsic factors affected the women's BCO levels in pregnancy.

DESIGN

A prospective observational study.

SETTING

A university obstetric hospital in an urban setting in Ireland.

PARTICIPANTS

Women (n=250) and their partners (n=54) were recruited at their first antenatal visit. Women <18 years and those who did not understand English were excluded. A booking history, including recording of smoking status, was collected by midwives. Following this, women were recruited and completed a detailed research questionnaire on smoking and extrinsic/environmental BCO sources. A BCO test was performed on both the woman and her partner.

PRIMARY AND SECONDARY OUTCOME MEASURES

The number of self-reported smokers and those that were positive on the BCO test. The characteristics of women who disclosed and did not disclose smoking status. The effect of extrinsic factors on the BCO test results.

RESULTS

Based on the receiver-operating characteristic curve, a BCO cut-off point of ≥3 ppm was the optimal level to identify ongoing smoking. At booking history, 15% of women reported as current smokers. Based on BCO levels ≥3 ppm combined with self-reported smoking in the research questionnaire, the rate increased to 25%. Non-disclosers had similar characteristics to non-smokers. No extrinsic factors affected maternal BCO levels.

CONCLUSIONS

Based on self-report and BCO levels, a quarter of women presenting for antenatal care continued to smoke, but only 60% reported their smoking to midwives. BCO measurement is an inexpensive, practical method of improving identification of maternal smoking, and it was not effected by extrinsic sources of BCO. Improved identification means more smokers can be supported to stop smoking in early pregnancy potentially improving the short-term and long-term health of both mother and child.

Carboxyhaemoglobin Levels among Traders Exposed to Vehicular Emissions in Three Motor Parks in Ibadan, Nigeria

Carbon monoxide (CO) remains a leading cause of work-related chemical poisoning. Vehicular emissions are the primary daily ambient source of CO in urban Nigerian motor parks, where there have been few human exposure studies. Using a cross-sectional comparative design, we assessed carboxyhaemoglobin levels (% COHb), a biomarker of CO exposure, among traders at three motor parks (AMP, IMP, and NMP) and other traders (nonmotor park workers) in Ibadan, Nigeria, using a noninvasive pulse CO-dosimeter (Rad 57). Ninety-three traders were proportionally allocated between motor parks; 93 other traders were selected based on specific study inclusion criteria. Mean ages of motor park traders and other traders were comparable, 37.8 ± 11.1 and 38.7 ± 9.6, respectively. Mean % COHb for traders (range 3-22) at AMP, IMP, and NMP was 11.2 ± 3.8, 11.6 ± 3.1, and 12.2 ± 3.3, respectively, while mean % COHb for other traders was about three times lower, 4.1 ± 1.7 (range 2-8). Overall, mean % COHb for motor park traders, 11.7 ± 3.3, was also significantly higher than for other traders (p < 0.05). Nevertheless, mean % COHb for both groups exceeded the current World Health Organization guideline, 2.5%. This study suggested that motor park traders have higher % COHb and thus are highly susceptible to exposure and more vulnerable to known risks of adverse health effects from exposure to CO.

Smoking behaviour and sensations during the pre-quit period of an exercise-aided smoking cessation intervention

INTRODUCTION

Previous research has shown reductions in cigarette consumption during the pre-quit period of exercise-aided smoking cessation interventions. Smoking topography and sensation patterns during this period is unknown and may provide valuable insight into compensation and cessation readiness.

METHODS

Female smokers (N = 236, M age = 43, M cigarettes/day = 17.0) enrolled in an exercise-aided smoking cessation intervention self-reported daily cigarette use and cigarette sensory experiences. Breath carbon monoxide and smoking topography data were collected during the period leading up to the targeted quit date (i.e., baseline, week 1, and week 3), which was set for week 4.

RESULTS

Repeated measures ANOVAs revealed that cigarette consumption (p < 0.001, eta = 0.32), carbon monoxide (p < 0.001, eta = 0.14), puff duration (p = 0.01, eta = 0.05), smoking satisfaction (p < 0.001, eta = 0.34), psychological reward (p < 0.001, eta = 0.43), enjoyment of respiratory tract sensations (p < 0.001, eta = 0.29), and craving (p < 0.001, eta = 0.39) decreased, whereas average puff flow (p = 0.01, eta = 0.05) increased.

CONCLUSIONS

This is the first study to establish that regular exercise during the pre-quit period served as a conduit for facilitating behavioral and sensory harm reduction with cigarettes. Furthermore, the pattern of change observed between cigarette consumption and smoking topography does not support compensation. These findings imply that female smokers who exercise prior to a quit attempt are in a favourable state to achieve cessation.

Correlation between clinical severity and different non-invasive measurements of carbon monoxide concentration: A population study

Objectives

Carbon monoxide (CO) poisoning is a major concern in industrialized countries. Each year, thousands of victims, resulting in approximately 100 fatalities, are encountered in France. The diagnosis of CO poisoning is challenging; while carboxyhemoglobin (COHb) may be useful, it is a weak indicator of the severity of CO poisoning. This weak indicator may be a result of the delay between poisoning occurrence and the blood assay. Two apparatuses, CO oximeters and exhaled CO analyzers, now permit COHb to be determined outside hospitals. Our hypothesis is that these instruments allow the early measurement of COHb concentrations, which are more correlated with the severity of poisoning, expressed using the poisoning severity score (PSS).

Design

In an observational and retrospective cohort study, the distribution of COHb measurements obtained by CO oximetry or by exhaled CO analyzers was compared between groups of severity expressed using the PSS.

Setting

Data were collected in the Paris area from January 2006 to December 2010 by the French Surveillance System of CO poisoning.

Participants

All patients with CO poisoning reported to the French Surveillance System of CO poisoning.

Results

There was a significant difference in the COHb values obtained by CO oximetry between groups stratified according to PSS (p<0.0001). A significant difference in the values of exhaled CO was also observed between PSS groups (p = 0.006), although the relationship was not linear.

Conclusions

The COHb concentrations measured using CO oximetry, but not those measured using exhaled CO analyzers, were well correlated with the severity of CO poisoning.

Influence of air pollution on exhaled carbon monoxide levels in smokers and non-smokers. A prospective cross-sectional study

BACKGROUND

The poor air quality and cigarette smoking are the most important reasons for increased carbon monoxide (CO) level in exhaled air. However, the influence of high air pollution concentration in big cities on the exhaled CO level has not been well studied yet.

OBJECTIVES

To evaluate the impact of smoking habit and air pollution in the place of living on the level of CO in exhaled air.

METHODS

Citizens from two large cities and one small town in Poland were asked to complete a survey disclosing their place of residence, education level, work status and smoking habits. Subsequently, the CO level in their exhaled air was measured. Air quality data, obtained from the Regional Inspectorates of Environmental Protection, revealed the differences in atmospheric CO concentration between locations.

RESULTS

1226 subjects were divided into 4 groups based on their declared smoking status and place of living. The average CO level in exhaled air was significantly higher in smokers than in non-smokers (p<0.0001) as well as in non-smokers from big cities than non-smokers from small ones (p<0.0001). Created model showed that non-smokers from big cities have odds ratio of 125.3 for exceeding CO cutoff level of 4ppm compared to non-smokers from small towns.

CONCLUSIONS

The average CO level in exhaled air is significantly higher in smokers than non-smokers. Among non-smokers, the average exhaled CO level is significantly higher in big city than small town citizens. These results suggest that permanent exposure to an increased concentration of air pollution and cigarette smoking affect the level of exhaled CO.

Associations of Exhaled Carbon Monoxide and Fractional Exhaled Nitric Oxide with Metabolic Syndrome: A Cohort Study

Exhaled carbon monoxide (eCO) and fractional exhaled nitric oxide (FeNO) could reflect underlying inflammatory and oxidative stresses, which play important roles in pathogenetic pathways of metabolic syndrome (MetS). However, epidemiologic evidence was limited. We conducted a study in Wuhan-Zhuhai (WHZH) cohort of 3649 community participants to investigate the association between eCO, FeNO and MetS in both cross-sectional and prospective ways. The results showed that higher eCO and FeNO were associated cross-sectionally with a higher prevalence of MetS. The multivariable-adjusted odds ratios for MetS at baseline were 1.22 (95% confidence interval [CI]: 1.11 to 1.35) associated with per log eCO and 1.14 (95% CI: 1.00 to 1.30) associated with per log FeNO. During a follow-up of 3 years, 358/2181 new developed MetS cases were identified. Compared with lowest quartile of eCO and FeNO, the multivariable-adjusted risk ratios (95% CI) for MetS were 1.48 (1.06 to 2.06) related to the highest quartile of eCO. These findings remained consistent across sex but not smoking status, eCO was only associated with MetS in non-smokers when stratified by smoking status. In conclusion, our study demonstrated that eCO and FeNO were independently and positively associated with the prevalence of MetS cross-sectionally, while only eCO was positively related with the incidence of MetS prospectively.

Comparison between objective measures of smoking and self-reported smoking status in patients with asthma or COPD: are our patients telling us the truth?

OBJECTIVE:

Smoking prevalence is frequently estimated on the basis of self-reported smoking status. That can lead to an underestimation of smoking rates. The aim of this study was to evaluate the difference between self-reported smoking status and that determined through the use of objective measures of smoking at a pulmonary outpatient clinic.

METHODS:

This was a cross-sectional study involving 144 individuals: 51 asthma patients, 53 COPD patients, 20 current smokers, and 20 never-smokers. Smoking status was determined on the basis of self-reports obtained in interviews, as well as through tests of exhaled carbon monoxide (eCO) and urinary cotinine.

RESULTS:

All of the asthma patients and COPD patients declared they were not current smokers. In the COPD and asthma patients, the median urinary cotinine concentration was 167 ng/mL (range, 2-5,348 ng/mL) and 47 ng/mL (range, 5-2,735 ng/mL), respectively (p < 0.0001), whereas the median eCO level was 8 ppm (range, 0-31 ppm) and 5 ppm (range, 2-45 ppm), respectively (p < 0.05). In 40 (38%) of the patients with asthma or COPD (n = 104), there was disagreement between the self-reported smoking status and that determined on the basis of the urinary cotinine concentration, a concentration > 200 ng/mL being considered indicative of current smoking. In 48 (46%) of those 104 patients, the self-reported non-smoking status was refuted by an eCO level > 6 ppm, which is also considered indicative of current smoking. In 30 (29%) of the patients with asthma or COPD, the urinary cotinine concentration and the eCO level both belied the patient claims of not being current smokers.

CONCLUSIONS:

Our findings suggest that high proportions of smoking pulmonary patients with lung disease falsely declare themselves to be nonsmokers. The accurate classification of smoking status is pivotal to the treatment of lung diseases. Objective measures of smoking could be helpful in improving clinical management and counseling.

'Enter at your own risk': a multimethod study of air quality and biological measures in Canadian waterpipe cafes

BACKGROUND

Tobacco and non-tobacco-based waterpipe smoking has increased exponentially in many countries in recent decades, particularly among youth and young adults. Although tobacco smoking is banned in many indoor public places, waterpipe smoking, ostensibly non-tobacco, continues in Ontario and other jurisdictions where only tobacco smoking is prohibited. This study assessed air quality and exposure in waterpipe cafes using multiple methods and markers.

METHODS

Indoor (n=12) and outdoor (n=5) air quality was assessed in Toronto, Canada waterpipe cafes from 30 August to 11 October 2012. Real-time measurements of air nicotine, fine particulate matter less than 2.5 microns in diameter (PM2.5) and ambient carbon monoxide (CO) were collected in 2 h sessions. Levels of CO in breath were collected in non-smoking field staff before entering and upon leaving venues. Observations of occupant behaviour, environmental changes and venue characteristics were also recorded.

RESULTS

In indoor venues, mean values were 1419 µg/m(3) for PM2.5, 17.7 ppm for ambient CO, and 3.3 µg/m(3) for air nicotine. Levels increased with increasing number of active waterpipes. On outdoor patios, mean values were 80.5 µg/m(3) for PM2.5, 0.5 ppm for ambient CO, and 0.6 µg/m(3) for air nicotine. Air quality levels in indoor waterpipe cafes are hazardous for human health. Outdoor waterpipe cafes showed less harmful particulate levels than indoors, but mean PM2.5 levels (80.5 µg/m(3)) were still 'poor'.

CONCLUSIONS

Staff and patrons of waterpipe cafes are exposed to air quality levels considered hazardous to human health. Results support eliminating waterpipe smoking in hospitality venues indoors and out.

Normal values of exhaled carbon monoxide in healthy subjects: comparison between two methods of assessment

Background

In a previous study, exhaled carbon monoxide (eCO) has been assessed in healthy non-smokers with a photo acoustic spectrometer Brüel&Kjær 1312. Unexpectedly, values were higher than those reported in literature, which were mostly obtained with electrochemical analysers. This study was aimed to compare eCO values obtained with Brüel&Kjær 1312 and PiCO + Smokerlyzer, a largely utilized electrochemical analyser.

Methods

Thirty-four healthy subjects, 15 non-smokers and 19 smokers, underwent eCO assessment with Brüel&Kjær 1312 and PiCO + Smokerlyzer during a prolonged expiration (15 seconds). Brüel&Kjær 1312 assessed CO concentration 7 and 12 seconds after the beginning of expiration and displayed the mean value. PiCO + Smokerlyzer was utilized according to the manufacturer’s recommendations. In vitro, the two devices were tested with standard concentrations of CO in nitrogen (5, 9.9, 20, and 50 ppm), and the time needed by PiCO + Smokerlyzer readings to stabilize was assessed at different gas flows.

Results

Both Brüel&Kjær 1312 and PiCO + Smokerlyzer presented very good internal consistency. The values provided were strictly correlated, but at low test concentrations, the Brüel&Kjær 1312 readings were greater than the PiCO + Smokerlyzer, and vice versa. PiCO + Smokerlyzer overestimated the CO standard concentrations at 5 and 9.9 ppm by 20%, while Brüel&Kjær 1312 measures were correct. PiCO + Smokerlyzer readings stabilized in 12 seconds during in vitro tests and in 15 seconds during in vivo measurements, suggesting that the values displayed corresponded to the initial phase of expiration.

Conclusions

Differences between Brüel&Kjær 1312 and PiCO + Smokerlyzer may be explained because Brüel&Kjær 1312 measured CO levels in the middle and at the end of expiration while PiCO + Smokerlyzer assessed them in the initial part of expiration.

Attempting tobacco cessation--an oral physician's perspective

INTRODUCTION

Tobacco use is a global health care problem. Repetitive exposure to nicotine produces neuroadaptation resulting in nicotine dependence. Smoking is associated with a range of diseases, causing high levels of morbidity and mortality and is one of the leading causes of preventable deaths, with more than 4.6 million smokers worldwide dying each year from smoking related illnesses. Stopping smoking has major health benefits. Quitting at any age provides both short and long term benefits.

MATERIALS AND METHODS

45 patients attending the outpatient department at the Oxford Dental College, Bangalore, were randomly allocated to three groups of interventions namely placebo, counseling and nicotine replacement therapy (NRT). Initially each one was assessed for carbon monoxide levels using a breath analyser (pico smokerlyser bedfont UK). They were followed up for six months and the carbon monoxide levels were again assessed using the same instrument. The paired t test was used to compare the results before and after the intervention.

RESULTS

The scores before the initiation of intervention and after treatment were compared and all three interventions were found to be statistically significant after six months. It was noticed that patients with very low or low dependence followed by high dependence had good response in the placebo group (68% and 47.6% respectively), in the counseling group maximum response was seen in the medium followed by the very low group (61% and 59% respectively), and maximum response was seen in very high followed by the very low group with NRT (78.7% and 60.5% respectively).

CONCLUSION

The inference that can be drawn from the present study is that non-invasive, non pharmacological methods like placebo and counseling are effective in low to medium groups, and NRT is effective with higher nicotine dependence.

Human brain functional network changes associated with enhanced and impaired attentional task performance

How is the cognitive performance of the human brain related to its topological and spatial organization as a complex network embedded in anatomical space? To address this question, we used nicotine replacement and duration of attentionally demanding task performance (time-on-task), as experimental factors expected, respectively, to enhance and impair cognitive function. We measured resting-state fMRI data, performance and brain activation on a go/no-go task demanding sustained attention, and subjective fatigue in n = 18 healthy, briefly abstinent, cigarette smokers scanned repeatedly in a placebo-controlled, crossover design. We tested the main effects of drug (placebo vs Nicorette gum) and time-on-task on behavioral performance and brain functional network metrics measured in binary graphs of 477 regional nodes (efficiency, measure of integrative topology; clustering, a measure of segregated topology; and the Euclidean physical distance between connected nodes, a proxy marker of wiring cost). Nicotine enhanced attentional task performance behaviorally and increased efficiency, decreased clustering, and increased connection distance of brain networks. Greater behavioral benefits of nicotine were correlated with stronger drug effects on integrative and distributed network configuration and with greater frequency of cigarette smoking. Greater time-on-task had opposite effects: it impaired attentional accuracy, decreased efficiency, increased clustering, and decreased connection distance of networks. These results are consistent with hypothetical predictions that superior cognitive performance should be supported by more efficient, integrated (high capacity) brain network topology at greater connection distance (high cost). They also demonstrate that brain network analysis can provide novel and theoretically principled pharmacodynamic biomarkers of pro-cognitive drug effects in humans.

Iron-phthalocyanine complexes immobilized in nanostructured metal oxide as optical sensors of NOx and CO: NMR and photophysical studies

This paper presents the research that is currently undergoing in our group toward the development of optical sensing layers based on iron(II) phthalocyanine complexes immobilized on nanostructured solid supports. Several FePc - N donor ligands have been prepared and coated into different nanostructured metal oxides. Optical properties, chemical variables, analytical features, selectivity rates, response times and type of nanostructure supports have been evaluated; in some cases, interesting correlations between them have been deduced. In addition, thermostability studies have been carried out, providing access to a second generation of nanostructured metal oxides.

Design and rationale of the tobacco, exercise and diet messages (TEXT ME) trial of a text message-based intervention for ongoing prevention of cardiovascular disease in people with coronary disease: a randomised controlled trial protocol

Background Although supporting lifestyle change is an effective way of preventing further events in people with cardiovascular disease, providing access to such interventions is a major challenge. This study aims to investigate whether simple reminders about behaviour change sent via mobile phone text message decrease cardiovascular risk. Methods and analysis Randomised controlled trial with 6 months of follow-up to evaluate the feasibility, acceptability and effect on cardiovascular risk of repeated lifestyle reminders sent via mobile phone text messages compared to usual care. A total of 720 patients with coronary artery disease will be randomised to either standard care or the TEXT ME intervention. The intervention group will receive multiple weekly text messages that provide information, motivation, support to quit smoking (if relevant) and recommendations for healthy diets and exercise. The primary end point is a change in plasma low-density lipoprotein cholesterol at 6 months. Secondary end points include a change in systolic blood pressure, smoking status, quality of life, medication adherence, waist circumference, physical activity levels, nutritional status and mood at 6 months. Process outcomes related to acceptability and feasibility of TEXT ME will also be collected. Ethics and dissemination Primary ethics approval was received from Western Sydney Local Health Network Human Research Ethics Committee-Westmead. Results will be disseminated via the usual scientific forums including peer-reviewed publications and presentations at international conferences. Clinical trials registration number ACTRN12611000161921.

Exhaled carbon monoxide and risk of metabolic syndrome and cardiovascular disease in the community

BACKGROUND

Endogenous carbon monoxide (CO) at physiological concentrations is cytoprotective, whereas excess levels reflect underlying oxidative stress, inflammation, and vascular pathology and portend adverse clinical sequelae. However, the relation of exhaled CO to metabolic/vascular risk in the community is unknown.

METHODS AND RESULTS

We related exhaled CO, a surrogate measure of blood CO concentration, to the risk of developing new-onset metabolic syndrome and incident cardiovascular disease following 14 943 routine examinations (4139 unique participants; mean age, 46 years, 53% women) in the Framingham Heart Study. Baseline exhaled CO was associated with the presence of cardiometabolic risk factors (including smoking) and prevalent metabolic syndrome (odds ratio, 1.09 per log CO; 95% confidence interval, 1.02 to 1.17; P=0.01). During up to 4 years of follow-up, 1458 participants developed new-onset metabolic syndrome, and 416 experienced a first cardiovascular disease event. Compared with individuals in the lowest quartile of exhaled CO, those in the highest quartile were more likely to develop metabolic syndrome (odds ratio, 1.48; 95% confidence interval, 1.25 to 1.76; P<0.0001) and cardiovascular disease events (hazard ratio, 1.66; 95% confidence interval, 1.14 to 2.40; P=0.008) in multivariable analyses that included adjustment for smoking status.

CONCLUSION

In our community-based sample, higher exhaled CO levels predicted the development of metabolic syndrome and future cardiovascular disease events, underscoring the importance of this endogenous second messenger in the pathogenesis of metabolic and vascular risk.

Breath carbon monoxide and semiquantitative saliva cotinine as biomarkers for smoking

OBJECTIVE

As a biomarker of smoking, semiquantitative analysis of cotinine (NicAlert) offers several advantages over breath carbon monoxide (CO) and quantitative analysis of cotinine. Recent studies have used urine NicAlert and breath CO in combination to verify abstinence. However, no studies have evaluated the performance of saliva NicAlert against or in combination with breath CO.

METHOD

Breath CO, saliva NicAlert, and smoking history were compared in an urban population of daily smokers (n = 24) and nonsmokers (n = 25).

RESULTS

Saliva NicAlert predicted self-reported smoking with 100% sensitivity and 96% specificity. At a cutoff of > 5 ppm, breath CO had 100% sensitivity and 100% specificity in predicting self-reported smoking. Breath CO was positively correlated with saliva NicAlert and negatively correlated with minutes since last cigarette.

CONCLUSION

Saliva NicAlert had high sensitivity and specificity in identifying daily smokers. Compared to saliva NicAlert, breath CO level was more indicative of recent smoking. Future treatment studies should evaluate the performance of saliva NicAlert as an alternative to the urine test.

Effects of acute hypoventilation and hyperventilation on exhaled carbon monoxide measurement in healthy volunteers

Background

High levels of exhaled carbon monoxide (eCO) are a marker of airway or lung inflammation. We investigated whether hypo- or hyperventilation can affect measured values.

Methods

Ten healthy volunteers were trained to achieve sustained end-tidal CO2 (etCO2) concentrations of 30 (hyperventilation), 40 (normoventilation), and 50 mmHg (hypoventilation). As soon as target etCO2 values were achieved for 120 sec, exhaled breath was analyzed for eCO with a photoacoustic spectrometer. At etCO2 values of 30 and 40 mmHg exhaled breath was sampled both after a deep inspiration and after a normal one. All measurements were performed in two different environmental conditions: A) ambient CO concentration = 0.8 ppm and B) ambient CO concentration = 1.7 ppm.

Results

During normoventilation, eCO mean (standard deviation) was 11.5 (0.8) ppm; it decreased to 10.3 (0.8) ppm during hyperventilation (p < 0.01) and increased to 11.9 (0.8) ppm during hypoventilation (p < 0.01). eCO changes were less pronounced than the correspondent etCO₂ changes (hyperventilation: 10% Vs 25% decrease; hypoventilation 3% Vs 25% increase). Taking a deep inspiration before breath sampling was associated with lower eCO values (p < 0.01), while environmental CO levels did not affect eCO measurement.

Conclusions

eCO measurements should not be performed during marked acute hyperventilation, like that induced in this study, but the influence of less pronounced hyperventilation or of hypoventilation is probably negligible in clinical practice

The CHOICE (Choice of Health Options In prevention of Cardiovascular Events) replication trial: study protocol

Background

Although morbidity and mortality from coronary heart disease (CHD) are high, only a minority of acute coronary syndrome (ACS) survivors accesses an effective secondary prevention program. We aim to determine whether the previously proven CHOICE program can be replicated at multiple sites and whether ongoing reinforcement further improves risk factor modification.

Methods/design

Participants eligible for but not accessing standard cardiac rehabilitation will be randomly allocated to either a previously tested 3-month CHOICE program or a 30-month CHOICE program (CHOICE-plus). Both groups will participate in individualised risk factor modules of differing duration that involve choice, goal setting and telephone follow-up for three months. CHOICE-plus will also receive additional face-to-face and telephone reinforcement between three and 30 months. At one site we will recruit a randomised control group, receiving conventional care. Primary outcomes are lipid levels, blood pressure, physical activity levels and smoking rates. Secondary outcomes include readmission rates, death, the number of risk factors, other modifiable risk factors, quality of life and process evaluation measures over three years.

Discussion

We present the rationale and design of a multi-centre, replication study testing a modular approach for the secondary prevention of CHD following an ACS.

Trial Registration

[Clinical Trial Registration Number, ACTRN12608000182392]

Brain monoamine oxidase A activity predicts trait aggression

The genetic deletion of monoamine oxidase A (MAO A), an enzyme that breaks down the monoamine neurotransmitters norepinephrine, serotonin, and dopamine, produces aggressive phenotypes across species. Therefore, a common polymorphism in the MAO A gene (MAOA, Mendelian Inheritance in Men database number 309850, referred to as high or low based on transcription in non-neuronal cells) has been investigated in a number of externalizing behavioral and clinical phenotypes. These studies provide evidence linking the low MAOA genotype and violent behavior but only through interaction with severe environmental stressors during childhood. Here, we hypothesized that in healthy adult males the gene product of MAO A in the brain, rather than the gene per se, would be associated with regulating the concentration of brain amines involved in trait aggression. Brain MAO A activity was measured in vivo in healthy nonsmoking men with positron emission tomography using a radioligand specific for MAO A (clorgyline labeled with carbon 11). Trait aggression was measured with the multidimensional personality questionnaire (MPQ). Here we report for the first time that brain MAO A correlates inversely with the MPQ trait measure of aggression (but not with other personality traits) such that the lower the MAO A activity in cortical and subcortical brain regions, the higher the self-reported aggression (in both MAOA genotype groups) contributing to more than one-third of the variability. Because trait aggression is a measure used to predict antisocial behavior, these results underscore the relevance of MAO A as a neurochemical substrate of aberrant aggression.

Low utilisation of cardiovascular risk reducing therapy in patients with acute coronary syndromes and non-obstructive coronary artery disease

BACKGROUND

Between 6-25% of patients undergoing coronary angiography for acute coronary syndrome (ACS) have non-obstructive coronary artery disease (NOCAD).

METHODS

One-hundred and eighty patients presenting with an ACS who were taking part in a risk factor modification study and had undergone coronary angiography were examined. We compared baseline characteristics, medical treatment and 12-month outcome in patients with NOCAD (<50% lumen diameter stenosis at coronary angiography) and obstructive CAD (> or = 50% lumen diameter stenosis at coronary angiography).

RESULTS

There were 29 (16%) patients with NOCAD and 151 (84%) with obstructive CAD (CAD). Patients with NOCAD were significantly younger, more likely to be female, had higher mean total cholesterol and LDL levels, and fewer received cardiac rehabilitation, treatment with statins, aspirin, ACE inhibitors, beta-blockers or clopidogrel. Over the next 12-months, there was no mortality or myocardial infarction in the NOCAD group compared to 2% in the CAD group, but 14% with NOCAD were readmitted for a cardiovascular cause including 2 patients (7%) who underwent percutaneous coronary intervention (PCI).

CONCLUSIONS

Patients presenting with ACS and NOCAD may not have a completely benign prognosis, and preventative strategies and therapies such as statins in this group of patients appear to be under-utilised.

Stability of carboxyhemoglobin in stored and mailed blood samples

BACKGROUND

Elevated blood carboxyhemoglobin (COHb) levels are used to confirm a clinical diagnosis of exposure to carbon monoxide (CO) and, in some instances, assess severity of poisoning. However, many hospital laboratories cannot measure COHb because they do not have CO-oximeters. In such instances, blood samples are often sent to outside laboratories or with a transported patient for measurement at the receiving hospital. This study was conducted to assess the stability of COHb in stored and mailed blood samples anticoagulated with heparin.

METHODS

Adult human blood was drawn into standard sample tubes anticoagulated with sodium heparin. Carbon monoxide gas was infused to raise the COHb level to 25% to 35%. Samples were then refrigerated or stored at room temperature, and serial COHb determinations were performed for 28 days. Additional samples were measured after being mailed locally or across the United States and back.

RESULTS

No significant changes in COHb levels were seen in samples stored either in refrigeration or at room temperature over a period of 28 days or in samples shipped without refrigeration locally or across the United States.

CONCLUSIONS

Carboxyhemoglobin levels in whole blood samples anticoagulated with heparin are stable with or without refrigeration for up to 4 weeks. If COHb measurement capability is not available, such samples may be shipped or transported with patients with confidence that the COHb level will be stable when measured at a later time.

Noninvasive measurement of carbon monoxide levels in ED patients with headache

OBJECTIVES

Carbon Monoxide (CO), the third most common cause of acute poisoning death, is easily overlooked in the emergency department (ED). Nonspecific complaints such as headache, weakness, or malaise may easily result in misdiagnosis. The objectives of this study are to determine the frequency of CO poisoning in patients presenting to the ED complaining of headaches and to determine the feasibility of using noninvasive CO analyzers as a screening tool.

METHODS

This prospective controlled study examined, during the winter months, adult patients presenting with a complaint of atraumatic, afebrile headaches. All subjects submitted a sample for a CO breath analyzer. Participants with elevated carboxyhemoglobin (COHb) levels (nonsmokers >2%, smokers >5%) underwent venous COHb testing. Control patients, without headaches, presenting to the ED were similarly studied.

RESULTS

We enrolled 170 subjects and 98 controls. Of the 170 subjects, 12 (7.1%) had elevated COHb levels confirmed by venous COHb levels. Of the 98 controls, 1 (1.0%) had an elevated COHb level (p < 0.05). There were no differences in demographic factors between the two groups (p > 0.16).

CONCLUSIONS

Noninvasive measurement of CO levels in ED patients with headaches is rapid and specific. During winter months, elevated CO levels are present in over 7% of ED patients with headaches.

High risk-factor level and low risk-factor knowledge in patients not accessing cardiac rehabilitation after acute coronary syndrome

OBJECTIVE

To document the risk-factor profile and risk-factor knowledge of patients with an acute coronary syndrome (ACS) not attending standard cardiac rehabilitation.

DESIGN AND SETTING

Cross-sectional comparison in a tertiary hospital.

PARTICIPANTS

Patients admitted to hospital with an ACS, residing within 20 km of the hospital, and without severe comorbidity who did not access cardiac rehabilitation (NCR) were compared with a group about to commence standard cardiac rehabilitation (SCR).

MAIN OUTCOME MEASURES

Risk-factor profile, knowledge of risk factors via face-to-face assessment, quality of life.

RESULTS

Of the 446 patients eligible for cardiac rehabilitation, 208 attended for assessment (NCR: n = 144; SCR: n = 64). The NCR group had higher mean (+/- SEM) low-density lipoprotein (LDL) cholesterol levels (2.6 +/- 0.1 v 2.3 +/- 0.1; P = 0.02), and were more likely than the SCR group to have a total cholesterol level of > 4.0 mmol/L (78% v 53%; P < 0.001) and an LDL cholesterol level > 2.5 mmol/L (47% v 25%; P = 0.01). They were more likely than the SCR group to be physically inactive (77% v 22%; P < 0.001); obese (46% v 33%; P = 0.04); depressed (21% v 5%; P < 0.001); or current smokers (21% v 1%; P < 0.001). Compared with the SCR group, the NCR group also had higher risk scores (LIPID risk score) (4.5 v 2.1; P < 0.001); lower quality of life (Medical Outcome Short Form [SF-36] Health Survey); and significantly poorer knowledge of risk factors. Among patients with at least two modifiable cardiac risk factors, the NCR group were less likely than the SCR group to be able to state at least one risk factor (24% v 38%; P < 0.001).

CONCLUSIONS

Patients not participating in cardiac rehabilitation after an ACS have more adverse risk profiles and poorer knowledge of risk factors compared with those about to commence cardiac rehabilitation. Alternate models for secondary prevention are required to improve health outcomes in patients not attending cardiac rehabilitation.

Carboxyhemoglobin measurement by hospitals: implications for the diagnosis of carbon monoxide poisoning

Most case definitions for carbon monoxide (CO) poisoning include demonstration of an elevated blood carboxyhemoglobin (COHb) concentration. Further, it is generally believed that treatment of CO poisoning is more effective when performed as soon as possible after the exposure. This suggests that a hospital's inability to measure blood COHb could lead to delayed or missed diagnosis or treatment. This study evaluated the ability of hospitals in the Pacific Northwest to measure COHb levels. The clinical laboratory of every acute care hospital in Washington, Idaho, Montana, and Alaska was surveyed regarding the ability to measure COHb levels, the method utilized and the time required. If they could not measure COHb, they were asked whether samples are sent elsewhere, the location of the referral laboratory, and time required. Results were then compared to the list of hospitals referring CO-poisoned patients to a regional center for hyperbaric oxygen therapy from 2003-2004. In the four states, only 44% of acute care hospitals have the capability to measure COHb. The remaining 56% send blood samples to other laboratories. The average time to get a result is 10 +/- 10 min in hospitals with co-oximetry and 904 +/- 1360 min in those without, a difference of 15 h (p < 0.0001). When samples are sent out, the average distance is 121 miles, often bypassing a hospital with CO-oximetry capability. Over 90% of CO-poisoned patients referred for hyperbaric treatment came from hospitals able to measure COHb. Fewer than one-half of acute care hospitals in a four-state region have the capability to measure COHb levels. This has the potential to significantly impact diagnosis or treatment of patients with acute CO poisoning.

Exhaled CO, a predictor of lung function?

BACKGROUND

Smoking is associated with an accelerated loss of lung function and inhalation accelerates the decline further. Exhaled CO reflects the exposure of smoke to the lungs.

AIM

To investigate whether self-reported inhalation and type of cigarette influenced the level of exhaled CO and whether CO could provide additional information to usual measures of smoking regarding prediction of present lung function and decline in lung function over an extended period of time.

METHOD

Cigarette smokers from the Copenhagen City Heart Study with valid measures of lung function and exhaled CO; in total 3738 subjects, 2096 women and 1642 men.

RESULTS

Subjects not inhaling had slightly lower exhaled CO values than those inhaling, but substantially higher values than non-smokers (P<0.001). Smokers of plain cigarettes had slightly lower CO values than smokers of filter cigarettes (P<0.001). Increasing CO levels were correlated to a lower FEV(1)%pred and to an accelerated decline in lung function. However, in multiple linear regression analyses these correlations were not significant.

CONCLUSION

Inhalation and type of cigarette affects exhaled CO levels. CO measures have no predictive value regarding neither present lung function nor decline in lung function with time in a population survey setting.

Prospective study of one million deaths in India: rationale, design, and validation results

BACKGROUND

Over 75% of the annual estimated 9.5 million deaths in India occur in the home, and the large majority of these do not have a certified cause. India and other developing countries urgently need reliable quantification of the causes of death. They also need better epidemiological evidence about the relevance of physical (such as blood pressure and obesity), behavioral (such as smoking, alcohol, HIV-1 risk taking, and immunization history), and biological (such as blood lipids and gene polymorphisms) measurements to the development of disease in individuals or disease rates in populations. We report here on the rationale, design, and implementation of the world's largest prospective study of the causes and correlates of mortality.

METHODS AND FINDINGS

We will monitor nearly 14 million people in 2.4 million nationally representative Indian households (6.3 million people in 1.1 million households in the 1998-2003 sample frame and 7.6 million people in 1.3 million households in the 2004-2014 sample frame) for vital status and, if dead, the causes of death through a well-validated verbal autopsy (VA) instrument. About 300,000 deaths from 1998-2003 and some 700,000 deaths from 2004-2014 are expected; of these about 850,000 will be coded by two physicians to provide causes of death by gender, age, socioeconomic status, and geographical region. Pilot studies will evaluate the addition of physical and biological measurements, specifically dried blood spots. Preliminary results from over 35,000 deaths suggest that VA can ascertain the leading causes of death, reduce the misclassification of causes, and derive the probable underlying cause of death when it has not been reported. VA yields broad classification of the underlying causes in about 90% of deaths before age 70. In old age, however, the proportion of classifiable deaths is lower. By tracking underlying demographic denominators, the study permits quantification of absolute mortality rates. Household case-control, proportional mortality, and nested case-control methods permit quantification of risk factors.

CONCLUSIONS

This study will reliably document not only the underlying cause of child and adult deaths but also key risk factors (behavioral, physical, environmental, and eventually, genetic). It offers a globally replicable model for reliably estimating cause-specific mortality using VA and strengthens India's flagship mortality monitoring system. Despite the misclassification that is still expected, the new cause-of-death data will be substantially better than that available previously.

End-expiratory carbon monoxide levels in healthy subjects living in a densely populated urban environment

Carbon monoxide (CO) has a high affinity for haemoglobin and is a common cause of poisoning in industry and the home. Exhaled CO levels in patients with respiratory disease have been reported but exhaled CO in a large cohort of healthy subjects grouped by age and gender has not been reported. Exhaled CO levels and spirometry lung function data were recorded from 1032 subjects at a university campus and two commercial plazas. Subjects were also asked to complete a respiratory symptom questionnaire. Ninety-eight subjects reported respiratory disease and were excluded from the study. Non-smoking male subjects (n=508) had higher exhaled CO levels (4.36+/-2.54 ppm) [range 0-21 ppm] compared with female (n=348) subjects (3.72+/-2.12 ppm) [range 0-14 ppm] (p<0.0005), and older subjects (>60 years) had lower exhaled CO levels compared with young subjects (<22 years) (p=0.018). Over 13% of non-smokers had an exhaled CO greater than 7 ppm. Smokers showed significantly higher exhaled CO levels compared with non-smokers (p<0.0005) and smokers who complained of frequent cough and sputum production had higher levels of exhaled CO compared with smokers without such complaints. Smoking history (pack-years) was directly related to age (r=0.59) but correlated inversely with forced expiratory flow in the 1st second (FEV1) (r=-0.29) and peak expiratory flow rate (PEFR) (r=-0.25) (p<0.05). If a city's micro environmental CO concentrations and human activity patterns is available, regular monitoring of exhaled CO in healthy subjects has the potential to be used as a functional index of air pollution.

Self-reported smoking status and exhaled carbon monoxide: results from two population-based epidemiologic studies in the North of England

STUDY OBJECTIVES

To investigate the validity of self-reported responses to questions on current smoking in two cohorts based in Northern England.

DESIGN

A cross-sectional population-based study (the Newcastle Heart Project [NHP]) and a follow-up of the Newcastle Thousand Families birth cohort established in 1947.

PATIENTS OR PARTICIPANTS

Participants included 1,189 members of the NHP and 410 members of the Newcastle Thousand Families cohort who completed a health and lifestyle questionnaire, including questions on current smoking, and attended a clinical examination, including testing for exhaled carbon monoxide between April 1993 and December 1998.

RESULTS

The number of self-reporting smokers for whom very low (ie, < 6 ppm) exhaled carbon monoxide levels were recorded varied between 9% in the Newcastle Thousand Families Study and 26% among the members of the NHP who were of South Asian origin. Using a cutoff of 8 ppm, 80% of self-reported smokers were identified in both the Newcastle Thousand Families study and in the NHP European population, but only 60% were identified in the NHP South Asian population. In each population, < 7% of nonsmokers had exhaled carbon monoxide measurements of > 6 ppm, with nonsmoking men more likely to have higher levels than nonsmoking women. Among the nonsmokers, the levels of exhaled carbon monoxide did not vary with respect to the smoking status of a partner or socioeconomic status.

CONCLUSIONS

Using a cutoff value of 6 ppm would potentially miss a large number of smokers, although this may vary with ethnicity. Epidemiologic studies should continue to use biochemical markers to validate responses to smoking surveys. However, the use of exhaled carbon monoxide measurements as a method of assessing the validity of self-reported smoking status may require additional analyses of whether the cutoff level should vary for different populations.