Exhaled CO2 Research Articles

Assessment of endotracheal tube placement in newborn infants: a randomized controlled trial.

International resuscitation guidelines recommend clinical assessment and exhaled CO2 to confirm tube placement immediately after intubation. However, exhaled CO2 devices can display false negative results. In comparison, any respiratory function monitor can be used to measure and display gas flow in and out of an endotracheal tube. However, neither method has been examined in detail. We hypothesized that a flow sensor would improve the assessment of tracheal vs esophageal tube placement in neonates with a higher success rate and a shorter time to tube placement confirmation when compared with the use of a quantitative end-tidal CO2 (ETCO2) detector. Between December 2013 and September 2014, preterm and term infants requiring endotracheal intubation were eligible for inclusion and randomly allocated to either ETCO2 ('ETCO2 group') or flow sensor ('flow sensor group'). All infants were analyzed according to their group at randomization (that is, analysis was by intention-to-treat). During the study period, a total of 110 infants (n=55 for each group) were randomized. Successful endotracheal tube placements were correctly identified in 100% of cases by the flow sensor compared with 72% of cases with the ETCO2 detector within 10 inflations (P<0.05). The median (interquartile range) number of inflations needed to identify successful tube placement was significantly lower in the flow sensor group with 2 (1 to 3) inflations vs 8 (6 to 10) inflations with the ETCO2 detector (P<0.001). A flow sensor would improve the assessment of successful endotracheal tube placement with a higher success rate and a shorter time compared with an ETCO2 detector.

Exhaled carbon monoxide is a marker of heavy nicotine dependence.

Exhaled CO level provides an objective measure of a patient's smoking status. The relationship between CO levels and nicotine dependence is controversial. The aim of this study is to evaluate the relationship between exhaled CO levels and nicotine dependence as well as to demonstrate that exhaled CO levels may be used as a marker of nicotine dependence. Two hundred eighty-nine patients (132 females, 157 males) were included in the study. Smoking duration, the age of smoking initiation, exhaled CO levels, and Fagerström Test for Nicotine Dependence (FTND) scores were recorded. The relationship between FTND scores and exhaled CO levels was investigated. There was a statistically significant correlation between FTND score and exhaled CO levels (P < 0.001). We found that a cut-off score of 7.5 ppm for exhaled CO may be useful as a marker for heavy smoking. The sensitivity and specificity of this cut-off score for exhaled CO was 69.3% and 49.3%, respectively (P < 0.001). We found that exhaled CO levels significantly correlated with FTND scores. For patients who are unable to provide reliable answers to questions in the FTND, exhaled CO measurements may be used as an alternative test for estimating the status of heavy smoking.

The Mofetta Tylicz – an example of carbonated water springs in the area of Tylicz (Beskid Sądecki, the Carpathians)

Abstract The paper characterise the group of CO2-rich (carbonated) water springs in the Carpathians, which are accompanied by exhalation of CO2. These springs called the Mofetta Tylicz are the example of the environmental and touristic unique object. We present geological and hydrogeological background as well as chemical analysis of the springs composition. The springs are characterised by the variability of the chemical composition of analysed groundwater, which indicates the need to implement a systematic monitoring. The monitoring would assess the reasons for this variability and allow the effective protection of spring waters of this area in the future.

Commentary on Kim et al., Effects of therapeutic relationship, expectancy, and credibility in breathing therapies for anxiety.

Kim and colleagues (2015) explored influences on clinical outcomes related to nonspecific therapeutic factors, addressing the importance of client expectancy and development of the therapeutic alliance. In the process, however, the authors carry forward conclusions from their prior research on treatment of panic that two opposing breathing retraining protocols are equally effective. Neither the experimental design nor the sample size of the current or previous study warrants reaching those conclusions. This commentary examines the findings of the current and previous studies and points to consistent trends that suggest that breathing retraining of panic patients may be enhanced by protocols aimed at raising exhaled CO2.

Computational fluid dynamics (CFD) modelling of air flow field, mean age of air and CO2 distributions inside a bedroom with different heights of conditioned air supply outlet

It was revealed in a previous related study that for an air conditioning (A/C) system used in a sleeping environment, the height of its supply air outlet would significantly affect its ventilation performance in terms of effectiveness. To further examine the underlying reasons of the differences in ventilation performance, the air flow field, distributions of mean age of air, air change efficiency and distributions of CO2 concentrations inside an experimental bedroom were numerically studied using CFD method under five different settings, where its supply air outlet was positioned at 5 different heights. The study results suggested that positing a supply air outlet at a lower level was effective in both saving energy and removing the exhaled CO2 in a breathing zone, and when a supply outlet was positioned at a higher level, less CO2 was removed from the region near the mouth of a sleeper.

On the validity of the 13C‐acetate breath test for comparing gastric emptying of different liquid test meals: a validation study using magnetic resonance imaging

(13) C-acetate breath testing (BT) is applied to assess and compare gastric emptying of liquid meals. Gastric half-emptying times (t50 ) from BT show offsets compared to t50 values from γ-scintigraphy and ultrasonography. Linear transformations have been proposed to correct these offsets. This investigation critically validates the BT for the assessment of liquid gastric emptying by using simultaneously recorded meal and total gastric content volume emptying data from magnetic resonance imaging (MRI). Data were collected during a recently published double-blind, randomized, cross-over MRI gastric emptying study of three (13) C-labeled enteral formulas differing in protein sources (PMID: 24699556). Breath testing-derived t50 was computed with the analysis methods commonly applied in gastric emptying research, i.e., the exponential-beta function and the Wagner-Nelson (WN) method, respectively. Breath testing t50 values from exponential-beta function and WN method showed a positive and negative offset to MRI data, respectively. Linear regression detected low concordance between MRI and both BT methods revealing meal specific and emptying rate-dependent offsets. The WN method showed worse agreement and correlation with MRI emptying data. Breath testing rather reflected meal volume than total gastric content volume emptying. This validation study indicates that the (13) C-acetate breath test may not be applied to compare gastric emptying of arbitrary liquid meals without prior validation by imaging methods. t50 values from BT are biased by (i) the properties of the meal and (ii) the selected method used for (13) CO2 exhalation analysis. No linear transformation common for all meals was applicable to correct the offsets between BT and MRI.

CO2 pulse and acid-base status during increasing work rate exercise in health and disease

The CO2 pulse (V˙CO2/heart rate), analogous to the O2 pulse (V˙O2/heart rate), was calculated during cardiopulmonary exercise testing and evaluated in normal and diseased states. Our aim was to define its application in its release in excess of that from V˙CO2/heart rate in the presence of impaired cardiovascular and lung function. In the current study, forty-five patients were divided into six physiological states: normal, exercise-induced myocardial ischemia, chronic heart failure, pulmonary vasculopathy, chronic obstructive pulmonary disease, and interstitial lung disease. We subtracted the O2 pulse from the CO2 pulse to determine the exhaled CO2 that could be attributed to CO2 pulse of buffering of lactic acid. The difference between the CO2 pulse and O2 pulse (V˙CO2/heart rate–V˙O2/heart rate) includes CO2 generated from HCO3− buffering of lactic acid. The accumulated CO2 per body mass was found to be significantly correlated with the corresponding [HCO3−] decrease (R2=0.72; P<0.0001). In summary, the increase in CO2 pulse over the O2 pulse accounted for the anaerobically-generated excess-CO2 in each of the physiological states and correlated with the decreases in the arterial Bicarbonate concentration.

Insulin sensitivity index (ISI0, 120) potentially linked to carbon isotopes of breath CO2 for pre-diabetes and type 2 diabetes.

New strategies for an accurate and early detection of insulin resistance are important to delay or prevent the acute onset of type 2 diabetes (T2D). Currently, insulin sensitivity index (ISI0,120) is considered to be a viable invasive method of whole-body insulin resistance for use in clinical settings in comparison with other invasive sensitivity indexes like homeostasis model assessment (HOMA), and quantitative insulin sensitivity check index (QUICKI). To investigate how these sensitivity indexes link the 13C/12C-carbon isotopes of exhaled breath CO2 to pre-diabetes (PD) and type 2 diabetes in response to glucose ingestion, we studied excretion dynamics of 13C/12C-isotopic fractionations of breath CO2. Here, we show that 13C/12C-isotope ratios of breath CO2 were well correlated with blood glucose, insulin, glycosylated-hemoglobin as well as with HOMA-IR and 1/QUICKI. Conversely, the strongest correlation was observed between 1/ISI0,120 and breath CO2 isotopes. Consequently, we determined several optimal diagnostic cut-off points of 1/ISI0,120 and 13CO2/12CO2-isotope ratios to distinctively track the evolution of PD prior to the onset of T2D. Our findings suggest that isotopic breath CO2 is a novel method for accurate estimation of ISI0,120 and thus may open new perspectives into the isotope-specific non-invasive evaluation of insulin resistance for large-scale real-time diabetes screening purposes.

Expedited CO2 respiration in people with Miltenberger erythrocyte phenotype GP.Mur.

In Southeast Asia, Miltenberger antigen subtype III (Mi.III; GP.Mur) is considered one of the most important red blood cell antigens in the field of transfusion medicine. Mi.III functions to promote erythrocyte band 3 expression and band 3-related HCO3− transport, with implications in blood CO2 metabolism. Could Mi.III affect physiologic CO2 respiration in its carriers? Here, we conducted a human trial to study the impacts of Mi.III expression in respiration. We recruited 188 healthy, adult subjects for blood typing, band 3 measurements, and respiratory tests before and after exercise. The 3-minute step exercise test forced the demand for CO2 dissipation to rise. We found that immediately following exercise, Mi.III + subjects exhaled CO2 at greater rates than Miltenberger-negative subjects. Respiration rates were also higher for Mi.III + subjects immediately after exercise. Blood gas tests further revealed distinct blood CO2 responses post-exercise between Mi.III and non-Mi.III. In contrast, from measurements of heart rates, blood O2 saturation and lactate, Mi.III phenotype was found to be independent of one’s aerobic and anaerobic capacities. Thus, Mi.III expression supported physiologic CO2 respiration. Conceivably, Mi.III + people may have advantages in performing physically enduring activities.

Spontaneously Breathing Preterm Infants Change in Tidal Volume to Improve Lung Aeration Immediately after Birth

To examine the temporal course of lung aeration at birth in preterm infants <33 weeks gestation. The research team attended deliveries of preterm infants <33 weeks gestation at the Royal Alexandra Hospital. Infants who received only continuous positive airway pressure were eligible for inclusion. A combined carbon dioxide (CO2) and flow-sensor was placed between the mask and the ventilation device. To analyze lung aeration patterns during spontaneous breathing, tidal volume (VT), and exhaled CO2 (ECO2) were recorded for the first 100 breaths. Thirty preterm infants were included with a total of 1512 breaths with mask leak <30%. Mean (SD) gestational age and birth weight was 30 (1) weeks and 1478 (430) g. Initial VT and ECO2 for the first 30 breaths was 5-6 mL/kg and 15-22 mm Hg, respectively. VT and ECO2 increased over the next 20 breaths to 7-8 mL/kg and 25-32 mm Hg, respectively. For the remaining observation period VT decreased to 4-6 mL/kg and ECO2 continued to increase to 35-37 mm Hg. Preterm infants begin taking deeper breaths approximately 30 breaths after initiating spontaneous breathing to inflate their lungs. Concurrent CO2 removal rises as alveoli are recruited. Lung aeration occurs in 2 phases: initially, large volume breaths with poor alveolar aeration followed by smaller breaths with elimination of CO2 as a consequence of adequate aeration.

Plasma ghrelin and liquid gastric emptying in children with functional dyspepsia consistent with post-prandial distress syndrome.

Adult studies indicate a role for ghrelin in functional dyspepsia (FD) mediated through ghrelin's effect on gastric emptying (GE). This study examines the relationship between ghrelin, liquid GE, and pain in children with FD. Thirteen FD patients reporting symptoms consistent with post-prandial distress syndrome (PDS) and 17 healthy controls were enrolled. All participants received a liquid meal containing (13) C-sodium acetate. Pain severity, liquid GE utilizing exhaled (13) CO2 from the sodium acetate breath tests (ABT), plasma acyl ghrelin (AG), and des-acyl ghrelin concentrations were measured at specific intervals over 240 min following ingestion. FD-PDS patients demonstrated lower mean baseline AG (14.8 ± 9.7 vs 27.2 ± 14.0 fmol/mL; p = 0.013), AG Cmax (24.6 ± 8.2 vs 40.5 ± 16.8 fmol/mL; p = 0.007), and AG flux (18.2 ± 7.8 vs 32.7 ± 17.3 fmol/mL; p = 0.015) than controls. The time to reach maximum exhaled (13) CO2 concentration (T max ) was longer in FD patients than controls (47.5 ± 18.5 vs 35.8 ± 11.8 min; p = 0.046). Significant relationships between ghrelin analyte ratios and ABT parameters were largely confined to control participants. FD-PDS in children is associated with lower fasting and maximum AG concentrations, and dampened AG flux. These data suggest a possible role for altered ghrelin physiology in the pathogenesis of PDS.

1-A-F-4. Respiratory fluctuation of pain related brain potential: Comparison of hand and foot stimulation

To study the effects of respiration on intraepidermal electrical stimulus-evoked potentials (IESEPs), sympathetic activities and pain sensations, we recorded electroencephalogram (EEG), sympathetic skin response (SSR), digital plethysmogram, subjective pain rating scale and exhaled CO2 in 8 healthy volunteers. The electrical stimulation to the epidermis of the dorsum of the left hand or foot was applied once or twice a minute when an exhaled CO2 level abruptly exceeded 20 mmHg (early expiratory phase, EP) or when it fell bellow 20 mmHg (early inspiratory phase, IP). The stimulus intensity was set at the threshold or 4 times the threshold, and unchanged during the experiment. Subjective pain rating scales fluctuated between “No hurt” and “Hurts a little bit” with an intensity of the threshold or between “Hurts a little bit” and “Hurts a little more” with an intensity of 4 times the threshold; but the former was more frequent for EP stimulation in both stimulus sites. The mean amplitudes of P400 in IESEPs and SSR were smaller for EP stimulation than IP stimulation in both stimulus sites. Our findings suggest that pain information processing fluctuates during respiration, and that pain may be partially gated in the expiratory phase in either stimulus site.

Is generalization of exhaled CO assessment in primary care helpful for early diagnosis of COPD?

BackgroundCOPD is largely under-diagnosed and once diagnosed usually at a late stage. Early diagnosis is thoroughly recommended but most attempts failed as the disease is marginally known and screening marginally accepted. It is a rare cause of concern in primary care and spirometry is not very common. Exhaled carbon monoxide (eCO) is a 5-seconds easy-to-use device dedicated to monitor cigarette smoke consumption. We aimed to assess whether systematic eCO measurement in primary care is a useful tool to improve acceptance for early COPD diagnosis.MethodsThis was a two-center randomized controlled trial enrolling 410 patients between March and May, 2013. Whatever was the reason of attendance to the clinic, all adults were proposed to measure eCO during randomly chosen days and outcomes were compared between the two different groups of patients (performing and not performing eCO). Primary outcome was the rates of acceptance for COPD screening.ResultsRate of acceptance for COPD screening was 28% in the eCO group and 26% in the other (P = 0.575). These rates increased to 48 and 51% in smokers (current and former). eCO significantly increased the rate of clinics during which a debate on smoking was initiated (42 vs. 24%, P = 0.001). eCO at 2.5 ppm was the discriminative concentration for identifying active smokers (ROC curve AUC: 0.935). Smoking was the only independent risk factor associated with acceptance for early COPD screening (OR = 364.6 (82.5-901.5) and OR = 78.5 (18.7-330.0) in current and former smokers, respectively) while eCO measurement was not.ConclusionsEarly COPD diagnosis is a minor cause of concern in primary care. Systematic eCO assessment failed to improve acceptance for early COPD screening.

Bespoke smoking cessation for people with severe mental ill health (SCIMITAR): a pilot randomised controlled trial

People with severe mental ill health are three times more likely to smoke but typically do not access conventional smoking cessation services, contributing to widening health inequalities and reduced life expectancy. We aimed to pilot an intervention targeted at smokers with severe mental ill health and to test methods of recruitment, randomisation, and follow up before implementing a full trial. The Smoking Cessation Intervention for Severe Mental Ill Health Trial (SCIMITAR) is a pilot randomised controlled trial of a smoking cessation strategy designed specifically for people with severe mental ill health, to be delivered by mental health nurses and consisting of behavioural support and drugs, compared with a conventional smoking cessation service (ie, usual care). Adults (aged 18 years or older) with bipolar disorder or schizophrenia, who were current smokers, were recruited from NHS primary care and mental health settings in the UK (York, Scarborough, Hull, and Manchester). Eligible participants were randomly allocated to either usual care (control group) or usual care plus the bespoke smoking cessation strategy (intervention group). Randomisation was done via a central telephone system, with computer-generated random numbers. We could not mask participants, family doctors, and researchers to the treatment allocation. Our primary outcome was smoking status at 12 months, verified by carbon monoxide measurements or self-report. Only participants who provided an exhaled CO measurement or self-reported their smoking status at 12 months were included in the primary analysis. The trial is registered at ISRCTN.com, number ISRCTN79497236. Of 97 people recruited to the pilot study, 51 were randomly allocated to the control group and 46 were assigned to the intervention group. Participants engaged well with the bespoke smoking cessation strategy, but no individuals assigned to usual care accessed NHS smoking cessation services. At 12 months, 35 (69%) controls and 33 (72%) people assigned to the intervention group provided a CO measurement or self-reported their smoking status. Smoking cessation was highest among individuals who received the bespoke intervention (12/33 [36%] vs 8/35 [23%]; adjusted odds ratio 2·9, 95% CI 0·8-10·5). We have shown the feasibility of recruiting and randomising people with severe mental ill health in a trial of this nature. The level of engagement with a bespoke smoking cessation strategy was higher than with a conventional approach. The effectiveness and safety of a smoking cessation programme designed particularly for people with severe mental ill health should be tested in a fully powered randomised controlled trial. National Institute of Health Research Health Technology Assessment Programme.

The effects of voluntary control of respiration on the excitability of the primary motor hand area, evaluated by end-tidal CO2 monitoring

ObjectiveTo investigate the effects of voluntary deep breathing on the excitability of the hand area in the primary motor cortex (M1). MethodsWe applied near-threshold transcranial magnetic stimulation (TMS) over M1 during the early phase of inspiration or expiration in both normal automatic and voluntary deep, but not “forced”, breathing in eight healthy participants at rest. We monitored exhaled CO2 levels continuously, and recorded motor-evoked potentials (MEPs) simultaneously from the abductor pollicis brevis, first dorsal interosseous, abductor digiti minimi, flexor digitorum superficialis, and extensor incidis muscles. ResultsWe observed that, during voluntary deep breathing, MEP amplitude increased by up to 50% for all recorded muscles and the latency of MEPs decreased by approximately 1ms, compared with normal automatic breathing. We found no difference in the amplitude or latency of MEPs between inspiratory and expiratory phases in either normal automatic or voluntary deep breathing. ConclusionsVoluntary deep breathing at rest facilitates MEPs following TMS over the hand area of M1, and MEP enhancement occurs throughout the full respiratory cycle. SignificanceThe M1 hand region is continuously driven by top-down neural signals over the entire respiratory cycle of voluntary deep breathing.

Sleep disorders in chronic obstructive pulmonary disease

Sleep disorders in chronic obstructive pulmonary disease (COPD) can occur in 60–70% of patients. They have adverse outcome in terms of both morbidity and mortality of COPD. The various sleep disorders seen in COPD are insomnia, restless leg syndrome (RLS), obstructive sleep apnea (OSA), nocturnal hypoventilation, and nocturnal oxygen desaturation (NOD). Of these disorders, insomnia and RLS can be diagnosed on history. OSA, sleep hypoventilation, and NODmay require type I polysomnography with/without transcutaneous or exhaled CO2 monitoring. Management consists of either conservative management or drug therapy for insomnia and RLS. If pharmacotherapy is required, ramelteon for insomnia and dopaminergic drug for RLS may be given. Treatment of OSA is continuous positive airway pressure, which relieves both OSA and COPD. Nocturnal hypoventilation usually requires oxygen along with noninvasive ventilator. Treatment of only NOD is controversial, but nocturnal oxygen may be given after ruling out nocturnal hypoventilation. This review emphasises the need of sleep disorders evaluation for comprehensive management of COPD.

End-Alveolar Carbon Monoxide As a Measure of Erythrocyte Survival and Hemolytic Severity in Sickle Cell Disease

Introduction: In sickle cell disease, polymerization of sickle hemoglobin gives rise to changes in the integrity and viability of the erythrocyte, leading to both extravascular and intravascular hemolysis and shortened life-span. Current gold standard techniques to estimate RBC survival require that a label be placed on the cells that can be followed while the RBCs age in the circulation. These studies are infrequently employed in practice, due to the need for multiple blood draws and an extended period of observation (6 weeks) in order to obtain the necessary time points. Endogenous CO is a technique that has been used in multiple studies to assess RBC survival, based upon the principal that virtually all CO produced in human beings results from cleavage of the α-methene bond of heme and is completely excreted via the lungs. Because RBC destruction accounts for approximately 80% of heme turnover in the body, endogenous CO production can be used as a quantitative indicator of RBC life span. Furne has reported on the development of a simple, rapid, and noninvasive method for determining RBC life span based on gas chromatography measurement of exhaled alveolar CO (EACO) concentration immediately upon awakening corrected for atmospheric CO, as determined with a device that simulates the body’s equilibration with CO.We set up to investigate the use of early morning end-alveolar CO (EACO) concentration as a quantitative measure of RBC life span and correlate it to indirect measurements of hemolytic rate in subjects with sickle cell disease.Material and methods: EACO was measured within 24 hours of breath collection in 67 SCD adult patients (67 HbSS, 4 HbSC and 1 HbSb-Thalassemia) and 14 HbAA race matched controls on an Ametrek TA 7000 Gas Purity Monitor. Subjects were at steady state, at least 30 days from transfusion or acute exacerbations. Breath samples were collected immediately upon awakening the same day as blood sampling for additional tests. EACO groups were compared using the Mann-Whitney test. EACO values were used to calculate the red blood cell lifespan by the method of Furne (PMID 12878986), using the calculation: RBC survival (days) = 1,380 · [Hb]/EACO. Correlation analyses are reported using Pearson’s correlation coefficient. The statistical significance was set at a two-side p < .05. Analyses were performed with R version 2.13.1 (2011-07-08).Results: EACO was nearly four-fold higher in patients than controls (median 2.25 vs. 0.58 ppm, p<.0001, figure). In patients with SCD, unadjusted EACO values were correlated with %HbS (p<.01), indirect markers of hemolysis: absolute reticulocyte count (p<.02), and percentage of reticulocytes (p<.01), indirect bilirubin (p<.001), and negatively with plasma nitrite (p<.02). EACO-derived red blood cell lifespan correlated negatively with LDH (p<.04), hematocrit (p<.01), hemoglobin (p<.06) indirect bilirubin (p<.01), absolute and percent reticulocyte counts (p<.01), AST (p<.01), and %HbS (p<.01).Conclusions: Our results confirm the usefulness of exhaled CO measurement as a marker of hemolysis and red cell survival and in substantial, prospective cohort of adult patients with SCD, confirming and considerably extending results of other investigators. EACO-derived RBC survival can be used to update estimates from Crosby in 1955 regarding the proportion of overall hemolysis falling into the extravascular and intravascular categories, the latter related to oxidative stress and scavenging of nitric oxide. This assay may be a useful biomarker in clinical trials of therapeutic interventions aimed at improving red cell life-span in SCD and other hemolytic anemias. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

The Malay version of the brief questionnaire on smoking urge: Translation and psychometric properties of the questionnaire

This study aimed to evaluate the psychometric properties of Malay translated version of the brief questionnaire of smoking urges (QSU-Brief). The translation procedure was done following the standard guidelines. The reliability and validity of the Malaysian version scale were evaluated based on the data collected from 133 Malaysian smokers. The internal consistency was calculated to assess the reliability. Factor analysis and construct validity were performed to validate psychometric properties of the scale. Total Cronbach’s alpha of the scale was 0.806. The exploratory factor analysis revealed two factors that accounted for 66.15% of the explained total variance. The first component consisted of items 1, 3, 6, 7, and 10, while the second component included the rest. The QSU-Brief total score had a significant positive relationship with exhaled CO level (r=0.24; P=0.005), number of cigarettes smoked per day (r=0.30; P<0.001) and other clinical factors. Items 2 and 5 loaded strongly on factor 2, whereas both items loaded ambivalently on two factors in the previous studies. This discrepancy might be clarified by language differences. The Malaysian QSU-Brief is a good candidate for evaluating urge to smoke in both clinical practice and clinical trials.

Ventilatory response to exercise in adolescents with cystic fibrosis and mild-to-moderate airway obstruction.

Data regarding the ventilatory response to exercise in adolescents with mild-to-moderate cystic fibrosis (CF) are equivocal. This study aimed to describe the ventilatory response during a progressive cardiopulmonary exercise test (CPET) up to maximal exertion, as well as to assess the adequacy of the ventilatory response for carbon dioxide (CO2) exhalation. Twenty-two adolescents with CF (12 boys and 10 girls; mean ± SD age: 14.3 ± 1.3 years; FEV1: 78.6 ± 17.3% of predicted) performed a maximal CPET. For each patient, data of a sex- and age matched healthy control was included (12 boys and 10 girls; mean ± SD age: 14.3 ± 1.4 years). At different relative exercise intensities of 25%, 50%, 75%, and 100% of peak oxygen uptake (VO2peak), breathing pattern, estimated ventilatory dead space ventilation (VD/VT ratio), minute ventilation (VE) to CO2 production relationship (VE/VCO2-slope), partial end-tidal CO2 tension (PETCO2), and the VE to the work rate (VE/WR) ratio were examined. VO2peak was significantly reduced in CF patients (P = 0.01). We found no differences in breathing pattern between both groups, except for a significantly higher VE at rest and a trend towards a lower VE at peak exercise in patients with CF. Significantly higher values were found for the estimated VD/VT ratio throughout the CPET in CF patients (P < 0.01). VE/VCO2-slope and PETCO2 values differed not between the two groups throughout the CPET. VE/WR ratio values were significantly higher in CF during the entire range of the CPET (P < 0.01). This study found an exaggerated ventilatory response (high VE/WR ratio values), which was adequate for CO2 exhalation (normal VE/VCO2-slope and PETCO2 values) during progressive exercise up to maximal exhaustion in CF patients with mild-to-moderate airway obstruction.

Gastric emptying rate in subjects with malocclusion examined by [13C] breath test

SUMMARY Masticatory function is significantly lower in individuals with malocclusion than in those with normal occlusion. Although several studies suggest that masticatory function influences gastrointestinal digestive function, the relationship between malocclusion and gastrointestinal symptoms has not been studied extensively. We hypothesised that insufficient masticatory function would increase the functional burden of the stomach and have some influence on the gastrointestinal system. The purpose of this study was to investigate masticatory function and gastric emptying rate in subjects with malocclusion. Eleven healthy dentate female volunteers and eleven female patients with malocclusion underwent a 13 C-acetate breath test with a liquid meal. Maximum 13 CO2 exhalation time (Tmax) was compared statistically between both groups. Masticatory function was assessed by colourchangeable chewing gum. In addition, the frequency scale for the symptoms of gastroesophageal reflux disease (FSSG) and questionnaires on food intake were given to both groups. The mean Tmax of the malocclusion group was significantly longer than that of the normal occlusion group (P = 0007). Masticatory performance, measured by colour-changeable gum and questionnaires, was significantly lower in the malocclusion group than in the normal occlusion group (P = 0023, P = 0003). There was no significant difference in the FSSG results between the two groups (P = 0262). This study suggested that there was a correlation between malocclusion and gastric emptying