Single-breath Technique Research Articles

Small Airways Dysfunction and Lung Hyperinflation in Long COVID-19 Patients as Potential Mechanisms of Persistent Dyspnoea.

Reticulation, ground glass opacities and post-infection bronchiectasis are present three months following hospitalisation in patients recovering from SARS-CoV-2 infection and are associated with the severity of acute infection. However, scarce data exist on small airways impairment and lung hyperinflation in patients with long COVID-19. To evaluate small airways function and lung hyperinflation in previously hospitalised patients with long COVID-19 and their association with post-COVID-19 breathlessness. In total, 33 patients (mean ± SD, 53 ± 11 years) with long COVID-19 were recruited 149 ± 90 days following hospital discharge. Pulmonary function tests were performed and lung hyperinflation was defined as RV/TLC ≥ 40%. Small airways function was evaluated by measuring the closing volume (CV) and closing capacity (CC) using the single-breath nitrogen washout technique (SBN2W). CC was 115 ± 28% pred. and open capacity (OC) was 90 ± 19. CC was abnormal in 13 patients (39%), CV in 2 patients (6.1%) and OC in 9 patients (27%). Lung hyperinflation was present in 15 patients, whilst the mean mMRC score was 2.2 ± 1.0. Lung hyperinflation was associated with CC (r = 0.772, p = 0.001), OC (r = 0.895, p = 0.001) and mMRC (r = 0.444, p = 0.010). Long COVID-19 patients present with small airways dysfunction and lung hyperinflation, which is associated with persistent dyspnoea, following hospitalisation.

Pediatric asthma inhaler technique: quality and content analysis of YouTube videos

Background Proper technique for using inhalers is crucial in treating pediatric asthma. YouTube offers a wide range of videos on pediatric inhaler technique, but there is a need to analyze the quality, reliability, and content of these resources. Aims This study aims to analyze the quality, reliability, and content of YouTube videos on pediatric asthma inhaler techniques. Methods The study has a descriptive, retrospective, and cross-sectional design. The research was conducted by searching YouTube using the “Pediatric Metered Dose Inhaler,” “Pediatric Accuhaler,” and “Pediatric Diskus.” The video’s popularity was measured using the Video Power Index. The quality and reliability of the videos were evaluated using the modified DISCERN and Global Quality Scale (GQS). Results This study analyzed 55 YouTube videos on the pediatric inhaler technique. 19 of the videos were related to the pMDI inhaler with a spacer for tidal breathing, 14 pMDI inhaler with a spacer for single breath, and 22 diskus device. Findings show that videos demonstrating the use of pMDI devices for single breath have more reliable modified DISCERN scores. However, videos related to tidal breathing are more popular than those showing the use of diskus devices and single breath. Based on the checklist for videos on diskus devices, the steps with the highest error rates are ‘Check dose counter’ at 72.7% and ‘Breathe out gently, away from the inhaler’ at 63.6%. A moderate correlation was observed between the modified DISCERN score and the GQS. Conclusions While YouTube videos on the pMDI single-breath technique may be useful for pediatric patients and caregivers, it is crucial for them to receive inhaler technique education from their healthcare provider. This study’s findings hold great significance for pediatric patients and caregivers, particularly those who rely on YouTube for health-related information.

Comparison of Pre-oxygenation with Single Vital Capacity Breath Technique and Tidal Volume Breathing Technique for Adult Patients Undergoing General Anaesthesia

Background: Pre-oxygenation before induction of general anaesthesia is widely used for enhancing oxygen reserves and preventing hypoxia. Several techniques for pre-oxygenation have been described. This study was designed to compare the PaO2 and ETO2 with single vital capacity breath technique (SVCB) and tidal volume breathing technique (TVB) for adult patients undergoing general anaesthesia.
 Methods: Fifty patients were pre-oxygenated with both techniques - first SVCB then TVB separated by five minutes of breathing room air or till ETO2 & PaO2 values reached baseline values (whichever was later). ABG samples & ETO2 readings were taken before pre-oxygenation & every thirty seconds for three minutes in both techniques.
 Results: Pre-test, mean PaO2 and ETO2 values of both techniques (SVCB and TVB) were similar. In SVCB technique, the mean PaO2 (mmHg) and ETO2 (%) significantly increased at 30 seconds (p ≤ 0.001) from 95.26 and 17.14 (pre-test time) to 304.34 and 92.48 respectively. In TVB technique, an exponential increase was noted. The mean PaO2 (mmHg) and ETO2(%) significantly increased at 180 seconds (p ≤ 0.001) from 96.26 and 16.26 (pre-test time) to 305.64 and 93.08 respectively. Peak values of oxygenation in both groups were similar but achieved at different time points.
 Conclusion: SVCB technique achieves high oxygenation rapidly but is not sustained thus can be used for rapid sequence induction though not recommended for difficult airway scenarios. TVB technique also achieves high oxygenation but steadily. TVB may be used for induction, including, rapid sequence induction but after 3-5 minutes of pre-oxygenation.

The relationship of lung recruitability assessment by recruitment to inflation ratio, electrical impedance tomography, and lung ultrasound: The research protocol

Background: Recently, the recruitment-to-inflation ratio (R/I ratio) from the single-breath technique has been proposed for identifying lung recruitability in acute respiratory distress syndrome (ARDS). This technique is based on measuring end-expiratory lung volume (EELV). Also, electrical impedance tomography (EIT) can estimate the EELV, providing the potential role of EIT in measuring the R/I ratio. In addition, the lung ultrasound was proved to identify lung recruitment. However, a study validating those techniques has not been conducted. Methods: We plan to conduct a single-center prospective physiological study on moderate to severe ARDS patients. The R/I ratio by single-breath technique and EIT will be collected before the recruitment maneuver. If the patient has no airway opening pressure (AOP), PEEP of 8 cmH2O will be set as PEEPlow. The PEEPhigh defines as initially set at +10 cmH2O from the PEEPlow. However, if the patients have AOP presence, AOP +10 cmH2O will be set as PEEPhigh The lung ultrasound score (LUS) will be performed at PEEPhigh and PEEPlow during the single-breath technique. Variables that will be used to analyze the relationship are recruited volume (Vrec), R/I ratio, and LUS. Hypothesis: We hypothesize that there are associations between the R/I ratio by both techniques and lung ultrasound score (LUS). Ethics: The study protocol has been approved by the ethics committee of the faculty of medicine, Ramathibodi Hospital, Mahidol University (COA.MURA2021/433).

Gas Exchange Impairment During COVID-19 Recovery.

Persistent impairment of pulmonary function and exercise capacity has been known to last for months or even years in the survivors who recovered from other coronavirus pneumonia. Some reports showed that subjects with coronavirus disease 2019 pneumonia after being discharged could have several sequelae, but there are few studies on gas exchange and exercise capacity complications in these subjects. To describe residual gas exchange abnormalities during recovery from coronavirus disease 2019 pneumonia. In an observational study, ∼90 d after onset of disease, we scheduled almost 200 subjects for an out-patient visit with pulmonary function testing and computed tomography of the lungs. Lung mechanics by using body plethysmography, gas exchange with diffusing lung capacity for carbon monoxide determined by the single-breath technique (DLCOsb) and diffusing lung capacity for nitric oxide determined by the single-breath technique (DLNOsb), and exercise ability by using the 6-min walk test (6MWT) were measured in the subjects. The results were compared between those who required invasive mechanical ventilation and those who did not. A total of 171 subjects were included, the majority (96%) had signs of residual pneumonia (such as an excess of high attenuation areas) on computed tomography of the lungs. The DLCOSB results were below the lower limit of the normal range in 29.2% of the subjects; during the 6MWT, 67% experienced oxygen desaturation ([Formula: see text]) > 4%; and, in 81 (47%), the dropped below 88%. Subjects who required invasive mechanical ventilation (49.7%) were more likely to have lower lung volumes, more gas exchange abnormality, less exercise capacity and more radiologic abnormality. Subjects who recovered from severe COVID-19 pneumonia continued to have abnormal lung function and abnormal radiologic findings.

Does Cold-Water Endurance Swimming Affect Pulmonary Function in Healthy Adults?

The acute effects of cold-water endurance swimming on the respiratory system have received little attention. We investigated pulmonary responses to cold-water endurance swimming in healthy recreational triathletes. Pulmonary function, alveolar diffusing capacity (DLCO), fractional exhaled nitric oxide (FENO) and arterial oxygen saturation by pulse oximetry (SpO2) were assessed in 19 healthy adults one hour before and 2.5 h after a cold-water (mean ± SD, 10 ± 0.9 °C) swim trial (62 ± 27 min). In addition, 12 out of the 19 participants measured pulmonary function, forced vital capacity (FVC) and forced expiratory volume in one second (FEV1) 3, 10, 20 and 45 min post-swim by maximal expiratory flow volume loops and DLCO by the single breath technique. FVC and FEV1 were significantly reduced 3 min post-swim (p = 0.02) (p = 0.04), respectively, and five of 12 participants (42%) experienced exercise-induced bronchoconstriction (EIB), defined as a ≥ 10% drop in FEV1. No significant changes were observed in pulmonary function 2.5 h post-swim. However, mean FENO and DLCO were significantly reduced by 7.1% and 8.1% (p = 0.01) and (p < 0.001), respectively, 2.5 h post-swim, accompanied by a 2.5% drop (p < 0.001) in SpO2. The absolute change in DLCO correlated significantly with the absolute decline in core temperature (r = 0.52; p = 0.02). Conclusion: Cold-water endurance swimming may affect the lungs in healthy recreational triathletes lasting up to 2.5 h post-swim. Some individuals appear to be more susceptible to pulmonary impairments than others, although these mechanisms need to be studied further.

Role of single-breath diffusing capacity for carbon monoxide in patients with chronic obstructive pulmonary disease

Background Chronic obstructive pulmonary disease (COPD) is a common, preventable, and treatable disease characterized by persistent respiratory symptoms and airflow limitation that is due to airway and/or alveolar abnormalities, usually caused by significant exposure to noxious particles or gases. The chronic airflow limitation that characterizes COPD is caused by a mixture of small airway disease (e.g. obstructive bronchiolitis) and parenchymal destruction (emphysema), the relative contributions of which vary from person to person. Aim The aim of the study was to measure diffusing capacity for carbon monoxide using single-breath technique in different stages of COPD. Patients and methods A total of 100 patients with COPD with mild to very severe obstruction were included in the study. Results There was a statistically significant negative (inverse) correlation between both transfer capacity of the lung (TLCO%) and KCO and PCO2 and HCO3, and there was a statistically significant positive (direct) correlation between both TLCO% and KCO and PO2, and arterial oxygen saturation. There was a statistically significant positive (direct) correlation between forced vital capacity %, forced expiratory volume in 1 s%, forced expiratory flow (FEF)25%, FEF50%, and FEF75% and each of TLCO% and KCO. Conclusion Decline in forced expiratory volume in 1 s/forced vital capacity is associated with decline in diffusing capacity of the lung for carbon monoxide, and it is affected more in patients with severe and very severe degrees of chronic obstructive pulmonary disease (COPD).

Epigenome-wide association study on diffusing capacity of the lung.

BackgroundEpigenetics may play an important role in the pathogenesis of lung diseases. However, little is known about the epigenetic factors that influence impaired gas exchange at the lung.AimTo identify the epigenetic signatures of the diffusing capacity of the lung measured by carbon monoxide uptake (the diffusing capacity of the lung for carbon monoxide (DLCO)).MethodsAn epigenome-wide association study (EWAS) was performed on diffusing capacity, measured by carbon monoxide uptake (DLCO) and per alveolar volume (VA) (as DLCO/VA), using the single-breath technique in 2674 individuals from two population-based cohort studies. These were the Rotterdam Study (RS, the “discovery panel”) and the Framingham Heart Study (FHS, the “replication panel”). We assessed the clinical relevance of our findings by investigating the identified sites in whole blood and by lung tissue specific gene expression.ResultsWe identified and replicated two CpG sites (cg05575921 and cg05951221) that were significantly associated with DLCO/VA and one (cg05575921) suggestively associated with DLCO. Furthermore, we found a positive association between aryl hydrocarbon receptor repressor (AHRR) gene (cg05575921) hypomethylation and gene expression of exocyst complex component 3 (EXOC3) in whole blood. We confirmed that the expression of EXOC3 in lung tissue is positively associated with DLCO/VA and DLCO.ConclusionsWe report on epigenome-wide associations with diffusing capacity in the general population. Our results suggest EXOC3 to be an excellent candidate, through which smoking-induced hypomethylation of AHRR might affect pulmonary gas exchange.

BET 1: Efficacy of different techniques using a metered-dose inhaler with Spacer to relieve symptoms in children with acute asthma

A shortcut review was carried out to establish which inhaler with spacer technique provides the greatest improvement in symptoms in children with acute asthma. Four relevant papers were identified for...

Do Faster Ultra-endurance Runners Have A Pulmonary Phenotype?

PURPOSE: The cardiopulmonary system of ultramarathon runners is exposed to prolonged periods of increased cardiac output and ventilation during exercise, which can stress the alveolar-capillary membrane. In order to determine if an adaptive pulmonary phenotype exists in ultramarathon runners, we tested the hypothesis that individuals who can sustain a faster race pace have superior pulmonary function and lung diffusing capacity. METHODS: Twenty-seven runners were assessed prior to a 100km ultramarathon at two different races (Hong Kong 100, N=19, CCC, N=8). Forced vital capacity (FVC) and forced expiratory volume in 1s (FEV1) were assessed via spirometry. Lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO) were measured using a single-breath technique at rest and during 3 stages of low level exercise. The DLNO/DLCO was calculated to assess the relative contribution of membrane conductance to capillary blood volume. The cohort was split into a faster group with an average finish time under 15 hours and a slower group with an average finish time above 21 hours to compare differences in pulmonary function. RESULTS: Baseline FVC and FEV1 were not different in the faster runners (FVC=5.2±0.5L; FEV1=4.2±0.5L) compared to the slower runners (FVC=5.2±1.1L; FEV1=4.1±0.8L), and did not differ from normative values, with overall percent predicted FVC and FEV1 at 105% and 92%, respectively. DLCO and DLNO did not differ between groups (fast, DLCO=33.2±6.0mmHg, DLNO=160.2±26.0mmHg; slow, DLCO=30.2±5.5mmHg, DLNO=155.2±27.6mmHg), however the ratio of DLNO/DLCO was lower in the faster group at rest (4.9 vs. 5.2, p=0.018) and during exercise (stage3: 4.9±0.2 vs.5.3±0.4, p<0.01). CONCLUSIONS: Resting lung function was not enhanced in faster runners, however the altered DLNO/DLCO ratio with light exercise suggests a greater relative contribution of capillary blood volume to membrane conductance might be associated with ultraendurance performance.

Pulmonary Rehabilitation for Exercise Tolerance and Quality of Life in IPF Patients: A Systematic Review and Meta-Analysis.

Objective The aim of this study is to evaluate the efficacy and safety of pulmonary rehabilitation (PR) in patients with idiopathic pulmonary fibrosis (IPF). Methods. Embase, PubMed, Cochrane Library, China National Knowledge Infrastructure (CNKI), Chongqing VIP (CQVIP), Wanfang Data, and Chinese Biomedical Literature Database (SinoMed) were comprehensively searched. Randomized controlled trials (RCTs) that investigated the effects of PR for IPF patients were included. Literature selection and data extraction were conducted by two review authors independently. The Cochrane Collaboration's Risk of Bias tool and RevMan software (version 5.3) were used to evaluate the quality of studies and conduct statistical analysis, respectively. Results. Seven studies (190 participants) were included. PR had a significant effect on six-minute walk distance (6MWD) (MD:48.60; 95%CI: 29.03 to 68.18; Z=4.87, P<0.00001), and 6MWD was improved more in subgroup analysis including studies conducted in Asia (MD: 53.62; 95%CI: 30.48 to 76.66; Z=4.54, P<0.00001) and Europe (MD:54.10; 95% CI: 26.65 to 101.56; Z=2.23, P=0.03). Forced vital capacity (FVC%) was higher (MD: 3.69; 95%CI: 0.16 to 7.23; Z=2.05, P=0.04). St. George's Respiratory Questionnaire (SGRQ)/IPF-specific SGRQ (SGRQ-I) total score was lower (MD: -7.87; 95% CI: -11.44 to -4.30; Z=4.32, P<0.0001). No significant effects were found for lung diffusing capacity determined by the single-breath technique (DLCO%) (MD: 3.02; 95%CI: -0.38 to 6.42; Z=1.74, P=0.08). Conclusions This study suggests that PR may enhance exercise capacity and improve quality of life in IPF patients. Besides, PR may also delay the decline of lung function of patients with IPF. However, further research should more fully assess the efficacy and safety of PR for IPF.

Early exercise pulmonary diffusing capacity of carbon monoxide after anatomical lung resection: a word of caution for fast-track programmes.

In healthy individuals, increasing pulmonary blood flow during exercise also increases the % of the diffusing capacity of the lungs for carbon monoxide (DLCO%), but its evolution after lung resection is unknown. In this study, our goal was to measure changes in exercise DLCO% during the first 3 days after anatomical lung resection. We performed a prospective observational study on consecutive patients with non-small-cell lung cancer scheduled for anatomical resection, except pneumonectomy, during a 6-month period. Patients underwent measurement of the DLCO% by a single-breath technique adjusted by the concentration of haemoglobin-before and after standardized exercise the day before and 3 consecutive days after surgery. The delta (Δ) variation (basal versus exercise) was calculated. The number of functioning resected segments was calculated by bronchoscopy. Postoperative pain and pleural air leak were estimated using a visual analogue scale and graduated conventional pleural drainage systems, respectively, and their influence on ΔDLCO each postoperative day was evaluated by linear regression analysis. Fifty-seven patients were included. The visual analogue scale of pain and pleural air leaks were not correlated to Δ values (model R2: 0.0048). The evolution of Δ values during 3 postoperative days showed a progressive recovery of values, but on the third day, DLCO% capacity during exercise was still impaired (P < 0.01), especially in patients who underwent a resection of more than 3 functioning segments. Physiological increase in DLCO% during exercise is still impaired on the third postoperative day in patients undergoing resection of more than 3 functioning pulmonary segments. This fact should be considered before discharging those patients after anatomical lung resection.

Heritability and genome-wide association study of diffusing capacity of the lung.

Although several genome-wide association studies (GWAS) have investigated the genetics of pulmonary ventilatory function, little is known about the genetic factors that influence gas exchange. The aim of the study was to investigate the heritability of, and genetic variants associated with the diffusing capacity of the lung.GWAS was performed on diffusing capacity of the lung measured by carbon monoxide uptake (DLCO) and per alveolar volume (VA) using the single-breath technique, in 8372 individuals from two population-based cohort studies, the Rotterdam Study and the Framingham Heart Study. Heritability was estimated in related (n=6246) and unrelated (n=3286) individuals.Heritability of DLCO and DLCO/VA ranged between 23% and 28% in unrelated individuals and between 45% and 49% in related individuals. Meta-analysis identified a genetic variant in ADGRG6 that is significantly associated with DLCO/VA Gene expression analysis of ADGRG6 in human lung tissue revealed a decreased expression in patients with chronic obstructive pulmonary disease (COPD) and subjects with decreased DLCO/VADLCO and DLCO/VA are heritable traits, with a considerable proportion of variance explained by genetics. A functional variant in ADGRG6 gene region was significantly associated with DLCO/VA Pulmonary ADGRG6 expression was decreased in patients with COPD.

Reference equations for pulmonary diffusing capacity of carbon monoxide and nitric oxide in adult Caucasians.

The aim of this study was to determine reference equations for the combined measurement of diffusing capacity of the lung for carbon monoxide (CO) and nitric oxide (NO) (DLCONO). In addition, we wanted to appeal for consensus regarding methodology of the measurement including calculation of diffusing capacity of the alveolo-capillary membrane (Dm) and pulmonary capillary volume (Vc).DLCONO was measured in 282 healthy individuals aged 18-97 years using the single-breath technique and a breath-hold time of 5 s (true apnoea period). The following values were used: 1) specific conductance of nitric oxide (θNO)=4.5 mLNO·mLblood-1·min-1·mmHg-1; 2) ratio of diffusing capacity of the membrane for NO and CO (DmNO/DmCO)=1.97; and 3) 1/red cell CO conductance (1/θCO)=(1.30+0.0041·mean capillary oxygen pressure)·(14.6/Hb concentration in g·dL-1).Reference equations were established for the outcomes of DLCONO, including DLCO and DLNO and the calculated values Dm and Vc Independent variables were age, sex, height and age squared.By providing new reference equations and by appealing for consensus regarding the methodology, we hope to provide a basis for future studies and clinical use of this novel and interesting method.

Reference Values for the Diffusing Capacity Determined by the Single-Breath Technique at Different Altitudes: The Latin American Single-Breath Diffusing Capacity Reference Project.

The lung diffusion capacity (DLCO) determined by the single-breath technique greatly helps in the differential diagnosis and classification of severity of common lung diseases. However, widespread use of single-breath DLCO tests in Latin America has been limited, in part, by the lack of appropriate reference values. Our objective was to derive robust reference equations for single-breath DLCO from healthy Hispanic adults, using the most recent guidelines and taking into account altitude above sea level and hemoglobin. We recruited healthy adults from Caracas (690 m), Santiago (650 m), Mexico City (2,240 m), and Bogota (2,640 m). DLCO testing was completed using an instrument that exceeds American Thoracic Society/European Respiratory Society 2005 guidelines for spirometry and single-breath DLCO and provided centralized training and a quality assurance program. We included 480 healthy Hispanic adults (58.3% women) with a mean age of 46 y (range 22-83 y). Their mean ± SD single-breath DLCO was 30.4 ± 9.2 mL/min/mm Hg. Results as a percentage of predicted by Crapo's reference values (the closest to obtained values) were 83 ± 10% (Caracas), 91 ± 10% (Santiago), 104 ± 17% (Mexico City), and 118 ± 19% (Bogota), and current suggested adjustments by hemoglobin or altitude did not correct differences, especially in Santiago and Caracas. We recommend these new single-breath DLCO reference equations to predict single-breath DLCO in Latin America performed with current instruments and procedures and including as a predictor altitude above sea level.

A new approach to detect early lung functional impairment in very light smokers

PurposeThe aim of our study is to investigate if lung carbon monoxide diffusing capacity (DLCO) measured during effort is able to detect early respiratory functional impairment. MethodsWe enrolled 25 very light smokers and 20 healthy non smokers. Subjects underwent plethysmography, DLCO (single breath technique) and calculated effective pulmonary blood flow (Qc) by rebreathing method. During exercise by cycle ergometer (duration 10±2min; recovery 11±3min) DLCO and Qc were calculated at 25% and 50% of theoretical maximum workload. ResultsAt baseline lung function and Qc did not differ between groups. DLCO and DLCO/Qc measured during exercise were significantly greater in non smokers (p<0.001); Qc was not statistically different. In very light smokers, DLCO, DLCO/Qc measured during exercise significantly correlated with the number of pack years (r=−0.60 p<0.001; r=−0.58 p<0.05; r=−0.55 p<0.05, respectively). ConclusionsIn very light smokers there is lung function impairment and our data show that DLCO during exercise may reveal this underlying early damage.

Values in Elderly People for Exhaled Nitric Oxide Study.

Ageing population is constantly increasing due to rising life expectancy; consequently, the percentage of the elderly patients with asthma is increasing, as well. Fractional exhaled nitric oxide (FeNO) is a biomarker of lung inflammation, and currently it is widely used in clinical practice for asthma diagnosis and monitoring. Yet, there are no data about normal values of FeNO in patients of more than 65 years of age with normal lung function. The aim of this study was to establish adult FeNO reference values for subjects older than 65 years, according to the international guidelines. FeNO was measured in 303 healthy, nonsmoking adults more than 65 years of age, with normal spirometry values measured using the online single-breath technique. The results were analyzed by chemiluminescent detection. The FeNO levels obtained range from 5.00 to 29.9 ppb, with a mean value of 12.48 ± 2.80 ppb. A significant association of FeNO levels with age (p < 0.05) was observed. There was no difference in FeNO values between men and women unlike what was observed in younger patients. FeNO levels in healthy controls over 65 years of age are influenced by age as in younger adults. However, there is no difference in FeNO values in male and female seniors, in contrast with what was found in younger adults in other studies. These data can be useful for the clinician to interpret the values of FeNO assessed during clinical practice.

Prediction equations for diffusing capacity (transfer factor) of lung for North Indians.

Background:Prediction equations for diffusing capacity of lung for carbon monoxide (DLCO), alveolar volume (VA), and DLCO/VA using the current standardization guidelines are not available for Indian population. The present study was carried out to develop equations for these parameters for North Indian adults and examine the ethnic diversity in predictions.Materials and Methods:DLCO was measured by single-breath technique and VA by single-breath helium dilution using standardized methodology in 357 (258 males, 99 females) normal nonsmoker adult North Indians and DLCO/VA was computed. The subjects were randomized into training and test datasets for development of prediction equations by multiple linear regressions and for validation, respectively.Results:For males, the following equations were developed: DLCO, −7.813 + 0.318 × ht −0.624 × age + 0.00552 × age2; VA, −8.152 + 0.087 × ht −0.019 × wt; DLCO/VA, 7.315 − 0.037 × age. For females, the equations were: DLCO, −44.15 + 0.449 × ht −0.099 × age; VA, −6.893 + 0.068 × ht. A statistically acceptable prediction equation was not obtained for DLCO/VA in females. It was therefore computed from predicted DLCO and predicted VA. All equations were internally valid. Predictions of DLCO by Indian equations were lower than most Caucasian predictions in both males and females and greater than the Chinese predictions for males.Conclusion:This study has developed validated prediction equations for DLCO, VA, and DLCO/VA in North Indians. Substantial ethnic diversity exists in predictions for DLCO and VA with Caucasian equations generally yielding higher values than the Indian or Chinese equations. However, DLCO/VA predicted by the Indian equations is slightly higher than that by other equations.

Impact of Single-Breath Mindfulness Technique on Physician Burnout and Stress

Introduction: Stress and burnout among health care providers can have serious repercussions. Mindfulness techniques, particularly when delivered by abbreviated training programs, have been studied for their success in managing symptoms and perceptions of stress and burnout among health care workers serving at the bedside, in clinic, as specialists, and in administration. Materials and Methods: Our suburban community hospital system introduced an eight week, video-module based, single-breath mindfulness technique training program to a group of 23 physicians with a range of experience (0-38 years; 48% primary care). Repeated measures ANOVA were used to evaluate changes across the study period (baseline, end of study, and 8 weeks post-intervention). Multiple linear regression was used to assess the relationship between burnout/stress measures at baseline and provider sex, age, years in practice, and field of practice (primary care or specialty). Results: 19 (83%) providers completed the program and 12 (52%) completed assessments at each time point. Significant improvements were observed across the study period in emotional exhaustion (p=0.01), personal accomplishment (p=0.007), and stress (p<0.001). The extent to which providers depersonalize their patients was not significantly impacted (p=0.14). No significant associations were observed between provider characteristics and burnout/stress metrics at baseline. However, at the α=0.10 level, primary care providers reported a significantly lower sense of personal accomplishment (-6.0 points, 95% CI: -12.2, 0.2 points; p=0.08) at baseline. Conclusions: Symptoms of stress and burnout are equally likely to be observed in providers across discipline, age, sex, and experience. A flexible, easy to use, single-breath based mindfulness program can yield significant improvements for these professionals.

Measurement of CO diffusion capacity (II): Standardisation and quality criteria

The diffusion capacity is the technique that measures the ability of the respiratory system for gas exchange, thus allowing a diagnosis of the malfunction of the alveolar-capillary unit. The most important parameter to assess is the CO diffusion capacity (DLCO). New methods are currently being used to measure the diffusion using nitric oxide (NO). There are other methods for measuring diffusion, although in this article the single breath technique is mainly referred to, as it is the most widely used and best standardized. Its complexity, its reference equations, differences in equipment, inter-patient variability and conditions in which the DLCO is performed, lead to a wide inter-laboratory variability, although its standardization makes this a more reliable and reproductive method. The practical aspects of the technique are analyzed, by specifying the recommendations to carry out a suitable procedure, the calibration routine, calculations and adjustments. Clinical applications are also discussed. An increase in the transfer of CO occurs in diseases in which there is an increased volume of blood in the pulmonary capillaries, such as in the polycythemia and pulmonary hemorrhage. There is a decrease in DLCO in patients with alveolar volume reduction or diffusion defects, either by altered alveolar-capillary membrane (interstitial diseases) or decreased volume of blood in the pulmonary capillaries (pulmonary embolism or primary pulmonary hypertension). Other causes of decreased or increased DLCO are also highlighted.