Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Exhalation”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 325 records · Page 18Linked to original sources
PubMed2002

Exhaled carbon monoxide is not elevated in patients with asthma or cystic fibrosis.

Increased levels of exhaled carbon monoxide (fractional concentration of CO in expired gas (FE,CO)), measured with an electrochemical sensor, have been reported in patients with inflammatory airway disorders, such as asthma, rhinitis and cystic fibrosis. This study aimed to evaluate these findings by using a fast-response nondisperse infrared (NDIR) analyser, and to compare these measurements with the fractional concentration of nitric oxide in exhaled air (FE,NO). Thirty-two steroid-naïve asthmatics, 24 steroid-treated asthmatics (16 patients with allergic rhinitis, nine patients with cystic fibrosis), and 30 nonsmoking healthy controls were included. CO measurements with the NDIR analyser were performed simultaneously with nitric oxide (NO) analysis (chemiluminescence technique). After 15 s of breath-hold, single-breath exhalations over 10 s were performed at two flow rates and end-tidal plateau concentrations were registered. An electrochemical CO sensor was used independently with an exhalation to residual volume, after a 15 s breath-hold. None of the two CO analysers gave a significant increase in FE,CO in the groups of patients with inflammatory airway disorders compared to controls. FE,NO was significantly elevated in steroid-naïve asthmatics and subjects with allergic rhinitis, but not in steroid-treated asthmatics and subjects with cystic fibrosis. Reducing exhalation flow rate by 50% gave a two-fold increase in FE,NO, while FE,CO was unaffected. A significant increase was seen in FE.CO, but not in FE,NO, when comparing with and without a 10 s breath-hold. In conclusion, the fractional concentration of carbon monoxide in expired gas was not increased in any of the patient groups, while the fractional concentration of nitric oxide in expired gas was significantly elevated in patients with steroid-naïve asthma and allergic rhinitis. Moreover, carbon monoxide was unaffected by flow rate but increased with breath-hold, suggesting an origin in the alveoli rather than the conducting airways.

Adolescent↗
PubMed1994

Reduced endogenous nitric oxide in the exhaled air of smokers and hypertensives.

We wanted to determine whether the production of endogenous nitric oxide (NO) is affected by cigarette smoking and various pathological conditions. Endogenously produced NO was measured by chemiluminescence in the exhaled air of 81 healthy volunteers (21 nonsmoking females (NSF), 12 smoking females (SF), 24 nonsmoking males (NSM) and 24 smoking males (SM)) and 38 patients (10 with hypertension, 10 intra- and 10 postoperative, 5 with renal failure and 3 with sepsis) entered the protocol. Subjects inspired from a NO-free air supply, which was also used to calibrate the NO-analyser. Endogenous NO production of volunteers was 18 +/- 8 per billion (ppb) depending on smoking habits. In exhaled air of NSF, NO concentration was 21 +/- 7 ppb, in SF 16 +/- 6 ppb, in NSM 19 +/- 8 ppb and in SM 15 +/- 6 ppb. Differences between smokers and nonsmokers were significant. Increased diastolic blood pressure was noted in SM compared to NSM (86 +/- 7 versus 78 +/- 7 mmHg). Patients with documented and treated hypertension (systolic and diastolic blood pressure: 141 +/- 18 and 82 +/- 9 mmHg) exhaled 13.7 +/- 5.3 ppb NO; hypertensive males 10 +/- 2 ppb NO and females 17 +/- 5 ppb NO. In patients with renal failure NO concentration in exhaled air was 20.2 +/- 6.8 ppb before and 19.8 +/- 6.4 ppb one hour after the onset of dialysis. In patients undergoing major surgery NO concentration was 5.6 +/- 2.5 ppb intra- and 10.3 +/- 3.5 ppb postoperatively. In three mechanically ventilated patients with documented septic syndrome, exhaled NO was 29.3 +/- 24 ppb.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1997

Is nitric oxide in exhaled air produced at airway or alveolar level?

The aim of this study was to determine whether the nitric oxide (NO) measured in exhaled air is produced at airway or alveolar level. Exhaled NO was measured using a chemiluminescence analyser, and carbon dioxide (CO2 concentration using a Morgan capnograph in single exhalations in 12 healthy subjects (mean age 32 yrs; 6 males and 6 females). For each subject, five exhalations were made directly into the NO analyser and five were made through a T-piece system, which allowed measurement of expiratory flow rate. The peak NO levels measured via the T-piece system were 41.2 (SEM 10.8) parts per billion (ppb), significantly lower than direct levels 84.8 (14.0) ppb (p<0.001). The levels of NO tended to rise to an early peak and plateau, while the CO2 levels continued to rise to peak late in the exhalation. The mean times to reach peak NO levels were 32.2 s (direct) and 23.1 s (T-piece), which were significantly different from that of peak CO2 levels 50.5 s (direct) and 51.4 s (T-piece) (p<0.001). At peak NO level, the simultaneous CO2 level mean 4.9% (SEM 0.14)%, was significantly lower than the peak CO2 reached, 5.8 (0.21)% (p<0.001). We conclude that peak nitric oxide levels are dependent on measurement conditions. There are significant differences between the time to peak of carbon dioxide and nitric oxide. Therefore, most nitric oxide, unlike carbon dioxide, is produced in airways and not at alveolar level.

Adolescent↗
PubMed1998

Increased exhaled nitric oxide in active pulmonary tuberculosis due to inducible NO synthase upregulation in alveolar macrophages.

Nitric oxide (NO) plays an important role in resistance to Mycobacterium tuberculosis infection. Our aim was to determine whether inducible NO synthase (iNOS) expression and generation of reactive nitrogen intermediates (RNI) by alveolar macrophages (AM) are increased in patients infected with M. tuberculosis. NO levels in the exhaled air of 19 active pulmonary tuberculosis (TB) and 14 control subjects were measured using a chemiluminescence NO analyser. The expression of iNOS on AM was studied by labelling AM with anti-mac iNOS polyclonal antibody analysed with a flow cytometer. The spontaneous generation of RNI by cultured AM was also measured. Data are presented as mean+/-SEM. The level of NO in exhaled air was higher in patients with active TB (16.2+/-1.2 parts per billion (ppb)) compared to control subjects (6.5+/-0.9 ppb), p<0.0001. Exhaled NO decreased with anti-TB treatment. Compared to control subjects (29.0+/-4.5 fluorescence intensity (FI)), iNOS expression on AM was upregulated in TB patients (86.3+/-12.5 FI) p<0.001 and the capacity for spontaneous generation of nitrite was enhanced. Nitrite production was inhibited by N(G)-monomethyl-L-arginine (L-NMMA), a competitive inhibitor of iNOS. The expression of iNOS on AM was related to the concentration of exhaled NO (r=0.66, p<0.001) and the nitrite generation capacity of AM (r(s)=0.77, p<0.001). We conclude that the increase in exhaled nitric oxide observed in patients with active pulmonary tuberculosis is due to an upregulation of inhaled NO synthase expression in alveolar macrophages which have an enhanced capacity for nitric oxide production.

Cells, Cultured↗
PubMed1998

Exhaled nitric oxide is not elevated in the inflammatory airways diseases of cystic fibrosis and bronchiectasis.

Airways inflammation has been associated with increased nitric oxide (NO) in the exhaled breath. It was, therefore, questioned whether exhaled NO could act as an indicator of the severity of airways inflammation in the chronic suppurative lung diseases cystic fibrosis (CF) and bronchiectasis. NO levels in a single exhalation were measured using a chemiluminescence analyser. Thirty-six patients with CF and 16 with bronchiectasis were studied and compared with 22 normal subjects and 35 asthmatic patients. All subjects were nonsmokers and all measurements were made when patients were clinically stable. In addition, exhaled NO was measured in 10 CF patients at the time of onset of an acute infective exacerbation and followed for 7 days during the treatment of the exacerbation in eight of the 10 patients. No significant differences were found in NO levels in patients with CF or bronchiectasis compared with normals (median 4.0, 5.5 and 4.4 parts per billion (ppb), respectively), but all were lower than in asthma patients (10.4 ppb). The NO levels in the CF patients at time of exacerbation were not increased and did not change during treatment. These data show that nitric oxide levels in the exhaled breath of patients with chronic suppurative lung diseases, in contrast to asthma, are not elevated, despite the presence of substantial airways inflammation. Possible explanations include poor diffusion of nitric oxide across increased and viscous airway secretions, removal of nitric oxide by reaction with reactive oxygen species in the inflamed environment and failure of upregulation of epithelial inducible nitric oxide synthase in chronic suppurative conditions.

Adult↗
PubMed1999

Sputum eosinophils and exhaled nitric oxide during late asthmatic reaction in patients with western red cedar asthma.

Examination of sputum for eosinophils and measurement of exhaled nitric oxide have been proposed as noninvasive methods of assessing airway inflammation in asthma. The use of these tests in the evaluation of patients with occupational asthma has not been reported. This study investigated the changes in sputum eosinophils and exhaled NO before and at intervals after inhalation challenge with plicatic acid in patients with suspected western red cedar asthma. Of 17 subjects who underwent challenge, nine had a positive bronchoconstrictor reaction (responders) and eight had a negative reaction (nonresponders). At 6 and 24 h after plicatic acid challenge, there was a significant increase in sputum eosinophils among responders, which was inversely related to the fall in forced expiratory volume in one second (FEV1) at 6 h. An increase in sputum eosinophils was also found in three nonresponders. Levels of exhaled NO increased at 24 h after challenge with plicatic acid in both responders and nonresponders, being significant only in nonresponders. No correlation was found between the increase in nitric oxide and the magnitude of the functional changes in the airways. There were significant correlations between the degree of sputum eosinophilia and the level of exhaled NO before and after methacholine and plicatic acid challenge. In conclusion, the late asthmatic reaction induced by plicatic acid in patients with western red cedar asthma is associated with an increase in sputum eosinophils. The usefulness of measuring sputum eosinophils and exhaled nitric oxide in the clinical evaluation of patients with suspected occupational asthma caused by low molecular weight compounds has yet to be determined.

Adult↗
PubMed1999

Exhaled nitric oxide and sputum eosinophil markers of inflammation in asthmatic children.

Exhaled nitric oxide and eosinophil sputum markers are considered noninvasive ways in which to evaluate airway inflammation in asthma. The aim of this study was to evaluate the relationships between these methods of evaluation in asthmatic children. In a cross-sectional study of 25 mild-moderate asthmatic children (aged 6-13 yrs, 10 patients on inhaled steroids) exhaled NO was measured along with induced sputum by inhalation of hypertonic saline solution. The sputum was processed for eosinophil count and eosinophil cationic protein (ECP) determination. Serum ECP and lung function (forced expiratory volume in one second (FEV1)) were also measured. A significant correlation was observed between exhaled NO and sputum eosinophils (r = 0.438, p = 0.032) as well as between sputum eosinophils and sputum ECP (r = 0.532, p<0.01). No correlation was observed among exhaled NO and serum ECP, sputum ECP, FEV1, respectively. Furthermore no correlation was observed between sputum eosinophil (%) and serum ECP and between sputum eosinophils and FEV1. There was no correlation among the investigated parameters in children treated with inhaled steroids. In conclusion, exhaled NO and sputum eosinophil counts are concordant in evaluating the degree of airway inflammation in patients with mild-to-moderate asthma. However, the association between these two noninvasive markers becomes less in steroid treated patients.

Adolescent↗
PubMed1999

Childhood asthma: exhaled nitric oxide in relation to clinical symptoms.

Bronchial asthma is associated with increased levels of exhaled nitric oxide which are suppressible by glucocorticosteroid inhalation. Children with bronchial asthma were studied to elucidate the relation between endogenous NO release and recent symptoms of bronchial obstruction. Twenty-five children with atopic asthma and 11 healthy control subjects were enrolled and exhaled NO was studied using chemiluminescence analysis. The subjects breathed purified air (<0.5 parts per billion (ppb) NO) exclusively through their mouths. Orally expired NO was measured during continuous nasal aspiration (1.3 L x min(-1)) to remove nasally produced NO. Nasal NO concentration was determined within the aspirated gas. Orally expired NO concentration was 2.5+/-0.3 ppb (mean +/-SEM) in healthy control subjects, 3.19+/-0.88 ppb (NS) in symptom-free children, and 8.28+/-0.81 ppb (p< or =0.01) in children with bronchial asthma who had had recent symptoms of bronchial obstruction. Similarly, in the subgroup of children treated regularly with inhaled glucocorticosteroids those with recent symptoms had significantly higher orally exhaled NO concentrations than healthy control subjects (9.5+/-1.5 ppb, p<0.05). The nasal NO concentration was 152.8+/-12.7 ppb in healthy control subjects and not significantly different in asthmatic children. In this group of asthmatic children, recent symptoms of bronchial obstruction were linked to significantly higher concentrations of NO in orally exhaled gas and to increased oral NO excretion rates. If substantiated by further studies, measurement of orally exhaled NO during nasal aspiration may become useful to monitor disease control in asthmatic children.

Asthma↗
PubMed2006

Performance of a new hand-held device for exhaled nitric oxide measurement in adults and children.

BACKGROUND: Exhaled nitric oxide (NO) measurement has been shown to be a valuable tool in the management of patients with asthma. Up to now, most measurements have been done with stationary, chemiluminescence-based NO analysers, which are not suitable for the primary health care setting. A hand-held NO analyser which simplifies the measurement would be of value both in specialized and primary health care. In this study, the performance of a new electrochemical hand-held device for exhaled NO measurements (NIOX MINO) was compared with a standard stationary chemiluminescence unit (NIOX). METHODS: A total of 71 subjects (6-60 years; 36 males), both healthy controls and atopic patients with and without asthma were included. The mean of three approved exhalations (50 ml/s) in each device, and the first approved measurement in the hand-held device, were compared with regard to NO readings (Bland-Altman plots), measurement feasibility (success rate with 6 attempts) and repeatability (intrasubject SD). RESULTS: Success rate was high (> or = 84%) in both devices for both adults and children. The subjects represented a FENO range of 8-147 parts per billion (ppb). When comparing the mean of three measurements (n = 61), the median of the intrasubject difference in exhaled NO for the two devices was -1.2 ppb; thus generally the hand-held device gave slightly higher readings. The Bland-Altman plot shows that the 95% limits of agreement were -9.8 and 8.0 ppb. The intrasubject median difference between the NIOX and the first approved measurement in the NIOX MINO was -2.0 ppb, and limits of agreement were -13.2 and 10.2 ppb. The median repeatability for NIOX and NIOX MINO were 1.1 and 1.2 ppb, respectively. CONCLUSION: The hand-held device (NIOX MINO) and the stationary system (NIOX) are in clinically acceptable agreement both when the mean of three measurements and the first approved measurement (NIOX MINO) is used. The hand-held device shows good repeatability, and it can be used successfully on adults and most children. The new hand-held device will enable the introduction of exhaled NO measurements into the primary health care.

Adolescent↗
PubMed2005

Influence of condensation temperature on selected exhaled breath parameters.

BACKGROUND: The effects of changes in cooling temperature on biomarker levels in exhaled breath condensate have been little investigated. The aim of the study was to test the effect of condensation temperature on the parameters of exhaled breath condensate and the levels of selected biomarkers. METHODS: Exhaled breath condensate was collected from 24 healthy subjects at temperatures of -10, -5, 0 and +5 C degrees. Selected parameters (condensed volume and conductivity) and biomarkers (hydrogen peroxide, malondialdehyde) were measured. RESULTS: There was a progressive increase in hydrogen peroxide and malondialdehyde concentrations, and condensate conductivity as the cooling temperature increased; total condensate volume increased as the cooling temperature decreased. CONCLUSION: The cooling temperature of exhaled breath condensate collection influenced selected biomarkers and potential normalizing factors (particularly conductivity) in different ways ex vivo. The temperature of exhaled breath condensate collection should be controlled and reported.

Adult↗
PubMed2006

Identification of acid reflux cough using serial assays of exhaled breath condensate pH.

BACKGROUND: Chronic cough is a common problem, frequently caused or exacerbated by acid reflux. Diagnosis of acid reflux cough is haphazard currently, often relying on long therapeutic trials of expensive medications. We tested the hypothesis that the most relevant mechanistic component of acid reflux in chronic cough is when it rises to the level of the airway where acid can potentially be aspirated. We further wished to determine if multi-sample exhaled breath condensate (EBC) pH profiles can identify chronic cough patients likely to respond to proton pump inhibitor therapy. METHODS: 59 subjects were recruited for this study. Initially we examined EBC pH (gas-standardized with Argon) in the setting of 15 experimental pharyngeal acid challenges to determine duration of EBC acidification. Subsequently, we enrolled 22 healthy subjects to determine a normal multi-sample exhaled breath condensate pH profile over 1-3 days. We additionally obtained multi-sample EBC pH profiles in 22 patients with chronic cough. These samples were timed to occur after coughing episodes. Exhaled breath condensate pH was measured after gas standardization. RESULTS: We found that exhaled breath condensate pH is substantially reduced for approximately 15 minutes after pharyngeal acid load. Healthy subjects rarely have any low EBC pH values (defined as < 7.4 based on a normative reference range from 404 healthy subjects). Patients with chronic cough who subsequently responded well to proton pump inhibition (n = 8) invariably had one or more cough episodes associated with EBC acidification. No patient who had normal EBC pH with each of their cough episodes reported a clinically relevant response to proton-pump inhibition. CONCLUSION: Patients whose cough responds to proton pump inhibition have transient exhaled breath condensate acidification with coughing episodes, supporting the role of airway acidification in reflux-triggered cough. Multi-sample EBC pH profiles, involving samples collected immediately subsequent to a coughing episode, may be useful appropriately to direct therapy to those patients with cough who have relevant acid reflux.

Journal Article↗
PubMed1999

Exhaled carbon monoxide levels elevated in diabetes and correlated with glucose concentration in blood: a new test for monitoring the disease?

PURPOSE: In diabetes, the interaction of glycated proteins with their cell-surface binding sites leads to oxidative stress and induction of the stress protein heme oxygenase (HO)-1. Considering that carbon monoxide (CO) is a product of HO activity, we studied the level of exhaled CO as a marker of oxidative stress in diabetes. METHODS: Eight patients with insulin-dependent diabetes mellitus (type 1) (4 men, 4 women; [mean +/- SEM] age, 50 +/- 8 years) were studied, of whom 2 had peripheral neuropathy and 1 had renal failure. Sixteen patients with non-insulin-dependent diabetes mellitus (type 2) (5 men, 11 women; age 63 +/- 8 years) were studied, of whom 2 had peripheral neuropathy. Glycosylated hemoglobin (HbA(1)c) levels were higher (7.4 +/- 0.3%) in patients with type 1 (mean duration of the disease, 20 +/- 5 years) than in type 2 (4.9 +/- 0.4%; p < 0.05; mean duration of the disease, 11 +/- 2 years). All of the patients were lifelong nonsmokers. RESULTS: Levels of exhaled CO were higher in patients with diabetes (type 1, 4.0 +/- 0.7 ppm; type 2, 5.0 +/- 0.4 ppm) when compared to 37 nonsmoking healthy subjects (20 men, 17 women; age, 33 +/- 3 years) (2.9 +/- 0.2 ppm; p < 0.05). There was a positive correlation between exhaled CO levels and the incidence of glycemia in all subjects (r = 0.52, p < 0.05) and the duration of diabetes (r = 0.48, p < 0.05), but there was not a strong correlation with concentrations of HbA(1)c (r = 0.06, p = 0.8). In addition, an oral glucose tolerance test was performed in five healthy nonsmoking volunteers (three men; age, 33 +/- 4 years). The maximal glucose increase (from 3.9 +/- 0.2 to 5.5 +/- 0.1 mmol/L at 15 min; p < 0.05) was associated with a significant increase in exhaled CO concentration (from 3.0 +/- 0.5 to 6.3 +/- 1.0 ppm; p < 0. 05). Both parameters returned to the baseline at 40 min after glucose administration. CONCLUSIONS: Elevated levels of exhaled CO in diabetes may reflect HO-1 induction and oxidative stress. The measurement of CO may be a new tool for disease monitoring.

Adult↗
PubMed2001

Exhaled nitric oxide is elevated in patients with progressive systemic sclerosis without interstitial lung disease.

BACKGROUND: Progressive systemic sclerosis (PSS) is a multisystem disorder of unknown etiology. Interstitial lung disease (ILD) is a major cause of mortality in this condition, and a major challenge in this regard is to identify parameters that would predict the onset or progression of ILD in patients with PSS. Abnormal cellularity of BAL fluid (BALF) has been demonstrated in patients with PSS without ILD. STUDY OBJECTIVES: We investigated exhaled nitric oxide (NO) as a noninvasive marker of pulmonary inflammation in patients with PSS with and without clinical and radiologic evidence of ILD. This was compared with the cellularity of BALF. Our hypothesis was that exhaled NO was elevated in patients with PSS without ILD who had abnormal BALF cellularity. SETTING: Pulmonology and rheumatology units of a university-based, tertiary referral hospital in Durban, South AFRICA: STUDY METHODS: Exhaled NO was measured using a chemiluminescence analyzer in 12 patients with PSS and ILD and in 12 patients without clinical or radiologic evidence of ILD and in 30 healthy control subjects. BAL was performed in patients with PSS with and without the presence of ILD and in six healthy control subjects. RESULTS: Subclinical inflammation was confirmed by increased inflammatory cell counts in BALF from patients with PSS without ILD. Exhaled NO (mean [SEM]) was elevated in patients with PSS without ILD at 9.6 (0.7) parts per billion (ppb) compared to patients with PSS and ILD at 6.2 (0.6) ppb (p < 0.001) and healthy control subjects at 6.3 (0.2) ppb (p < 0.001). CONCLUSION: Exhaled NO may therefore be an important noninvasive surrogate marker of inflammation in patients with PSS without ILD.

Adult↗
PubMed2003

Nitric oxide metabolites are not reduced in exhaled breath condensate of patients with primary ciliary dyskinesia.

STUDY OBJECTIVES: To investigate whether nitric oxide (NO) metabolites would be reduced in children affected by primary ciliary dyskinesia (PCD). DESIGN: Single-center observational study. PATIENTS: Fifteen children with PCD (seven boys; mean [+/- SEM] age, 10.3 +/- 0.7 years; mean FEV(1), 73 +/- 2.1% predicted) were recruited along with 14 healthy age-matched subjects (seven boys; mean age, 11.5 +/- 0.4 years; mean FEV(1), 103 +/- 5% predicted). INTERVENTIONS: We assessed the levels of nitrite (NO(2)(-)), NO(2)(-)/NO(3)(-) (NO(2)(-)/NO(3)(-)), and S-nitrosothiol in exhaled breath condensate, exhaled NO, and nasal NO from children with PCD compared to those in healthy children. MEASUREMENTS AND RESULTS: The mean exhaled and nasal NO levels were markedly decreased in children with PCD compared to those without PCD (3.2 +/- 0.2 vs 8.5 +/- 0.9 parts per billion [ppb], respectively [p < 0.0001]; 59.6 +/- 12.2 vs 505.5 +/- 66.8 ppb, respectively [p < 0.001]). Despite the lower levels of exhaled NO in children with PCD, no differences were found in the mean levels of NO(2)(-) (2.9 +/- 0.4 vs 3.5 +/- 0.3 microM, respectively), NO(2)(-)/NO(3)(-) (35.2 +/- 5.0 vs 34.3 +/- 4.5 microM, respectively), or S-nitrosothiol (1.0 +/- 0.2 vs 0.6 +/- 0.1 microM, respectively) between children with PCD and healthy subjects. CONCLUSION: These findings suggest that NO synthase activity may not be decreased as much as might be expected on the basis of low exhaled and nasal NO levels.

Breath Tests↗
PubMed2005

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.

Adult↗
PubMed2005

Exhaled ethane: an in vivo biomarker of lipid peroxidation in interstitial lung diseases.

BACKGROUND: Oxidative stress plays a role in the pathogenesis and progression of interstitial lung disease (ILD). Exhaled ethane is a product of lipid peroxidation that has been proposed as a biomarker of oxidative stress in vivo. OBJECTIVES: To determine whether the exhaled ethane level is elevated in patients with ILD and to compare it with other clinical parameters. METHODS: Breath samples were collected from 34 patients with ILD, including 13 with idiopathic pulmonary fibrosis (IPF), 9 patients with cryptogenic organizing pneumonia, 6 patients with collagen vascular disease-associated interstitial pneumonia, and 6 patients with pulmonary sarcoidosis. Gas samples were obtained at hospital admission and after 3 weeks. After each expired sample was concentrated using a trap-and-purge procedure, the ethane level was analyzed by gas chromatography. RESULTS: Exhaled ethane levels were elevated in ILD patients (n = 34, mean +/- SD, 8.5 +/- 8.0 pmol/dL) compared with healthy volunteers (n = 16, 2.9 +/- 1.0 pmol/dL; p < 0.001). Serial measurements revealed that increase and decrease of ethane levels were largely consistent with the clinical course. Four patients with IPF who had persistently high ethane levels died or deteriorated, whereas those with ethane levels < 5.0 pmol/dL remained stable or improved. Exhaled ethane concentrations were positively correlated with levels of lactate dehydrogenase (Spearman rank correlation coefficient [rs], 0.28, p = 0.026) and C-reactive protein (rs, 0.38, p = 0.025) and were inversely correlated with Pa(O2) (rs, - 0.40, p = 0.0026). Patients showing increased uptake on (67)Ga scintigraphy demonstrated higher ethane levels (n = 19, 7.5 +/- 5.7 pmol/dL) compared with those who did not show increased uptake on scintigraphy (n = 10, 3.0 +/- 2.4 pmol/dL; p < 0.01). CONCLUSIONS: Exhaled ethane is elevated in patients with ILD and is correlated with the clinical outcome, suggesting that it provides useful information about ongoing oxidative stress, and thereby disease activity and severity in ILD.

Adult↗
PubMed2001

Normal oxygenation and ventilation during snow burial by the exclusion of exhaled carbon dioxide.

OBJECTIVE: To confirm that the accumulation of exhaled carbon dioxide (CO2) is the principal cause of nonmechanical asphyxiation during avalanche burial by demonstrating that complete exclusion of exhaled CO2 during experimental snow burial results in normal oxygenation and ventilation utilizing the air within the snowpack. METHODS: In the experimental group, 8 healthy volunteers (mean age 32 years, range 19-44 years) were fully buried up to 90 minutes in compacted snow with a density ranging from 300 to 680 kg/ m3 at an elevation of 2385 m. The 6 men and 2 women breathed directly from the snow utilizing a device containing no air pocket around the inhalation intake, in addition to an extended exhalation tube running completely out of the snowpack to remove all exhaled CO2. Continuous physiologic monitoring included oxygen saturation, end-tidal CO2, inspired CO2, electrocardiogram, rectal core temperature, and respiratory rate. As controls, 5 of the 8 subjects repeated the study protocol breathing directly into a small, fist-sized air pocket with no CO2 removal device. RESULTS: In the experimental group, the mean burial time was 88 minutes, despite the absence of an air pocket. No significant changes occurred in any physiologic parameters in this group compared to baseline values. In contrast, the controls remained buried for a mean of 10 minutes (P = .003) and became significantly hypercapnic (P < .01) and hypoxic (P < .02). CONCLUSIONS: There is sufficient oxygen contained within a densified snowpack comparable to avalanche debris to sustain normal oxygenation and ventilation for at least 90 minutes during snow burial if exhaled CO2 is removed. The prolonged oxygenation observed during CO2 exclusion is irrespective of the presence of an air pocket.

Adult↗
PubMed2000

Increased bronchial nitric oxide production in patients with asthma measured with a novel method of different exhalation flow rates.

The concentration of nitric oxide (NO) in exhaled air is increased in patients with asthma, suggesting that measuring fractional exhaled NO concentration (FE(NO)) may be used to monitor asthmatic airway inflammation. However, increased FE(NO) is not specific for asthma, as other inflammatory lung diseases may also increase FE(NO). To augment the specificity of FE(NO) measurement, we tested a novel theoretical modelling of pulmonary NO dynamics that allows the approximation of alveolar NO concentration and bronchial NO flux separately by measuring FE(NO) at several exhalation flow rates. We measured FE(NO) at four exhalation flow rates in 10 steroid-naive asthmatics, 5 patients with extrinsic allergic alveolitis, and in 10 healthy controls. Both the asthmatics and the patients with alveolitis had significantly higher FE(NO) than the healthy controls. The increased NO concentration originated from the bronchial level in the asthmatics and from the alveolar level in the patients with alveolitis. In the second part of the study we assessed the repeatability of FE(NO) test, within-day and day-to-day (during two weeks) variation in FE(NO), and the effects of mouth pressure and cigarette smoking on FE(NO) in healthy volunteers. Repeatability of 10 subsequent measurements was high (coefficient of variation (CV) 4.6% +/- 0.4%), and no diurnal variation was found. The day-to-day variation during a 2-week period gave a CV of 10.6% +/- 1.0%. The magnitude of mouth pressure (5-20 cmH2O in adults, 5-40 cmH2O in children) during measurement had no effect on FE(NO). Smoking a cigarette caused a small and transient but statistically significant increase in FE(NO) at 1 and 5 min after smoking. In conclusion, FE(NO) measurement is highly repeatable with low day-to-day variation among healthy subjects. Our results also suggest that the present novel method of measuring FE(NO) at several exhalation flow rates can be used to approximate alveolar and bronchial contributions to FE(NO) separately and thus increase the clinical value of this test.

Adult↗