Lung "Comet Tails" in Healthy Individuals: Accumulation or Clearance of Extravascular Lung Water?

Parks, Jordan K, Courtney M. Wheatley-Guy, Glenn M. Stewart, Caitlin C. Fermoyle, Bryan J. Taylor, Jesse Schwartz, Briana Ziegler, Kay Johnson, Alice Gavet, Loïc Chabridon, Paul Robach, and Bruce D. Johnson. Lung "Comet Tails" in healthy individuals: accumulation or clearance of extravascular lung water? High Alt Med Biol. 24:230-233, 2023-Ultrasound lung comet tails (or B-lines) tend to be limited in number (<5) or absent under ultrasound examination, and the appearance of diffuse B-lines with lung sliding has been suggested to identify pulmonary edema. Clinical evaluation of B-lines has been utilized as a bedside test to assess pulmonary congestion in patients with heart failure. Exposure to altitude or prolonged exercise can alter fluid regulation and can lead to pulmonary congestion or edema. As such, B-lines have been utilized in the field to monitor for pathological lung fluid accumulation. However, ultrasound lung comet lines might not be as reliable for identifying extravascular lung water (EVLW) as previously thought in healthy individuals exercising at altitude where an increase in the number of ultrasound lung comets would reflect fluid buildup in the interstitial space of the alveoli and pulmonary capillaries. This report will focus on reviewing the literature and our data from a group of ultraendurance runners that completed the Ultra Trail Mont Blanc race that demonstrates that lung comet tails may not always be evidence of pathological fluid accumulation in healthy individuals and as such should be used to assess EVLW in concert with other diagnostic testing.

Influence of rapidly oscillating inspired O2 and N2 concentrations on pulmonary vascular function and lung fluid balance in healthy adults.

Introduction: Aircrew may experience rapidly oscillating inspired O2/N2 ratios owing to fluctuations in the on-board oxygen delivery systems (OBOG). Recent investigations suggest these oscillations may contribute to the constellation of physiologic events in aircrew of high-performance aircraft. Therefore, the purpose of this study was to determine whether these "operationally-relevant" environmental challenges may cause decrements in measures of pulmonary vascular physiology. Methods: Thirty healthy participants (Age: 29 ± 5 years) were recruited and assigned to one of the three exposures. Participants were instrumented for physiologic monitoring and underwent baseline cardiopulmonary physiology testing (ground level) consisting of a rebreathe method for quantifying pulmonary blood flow (Qc), pulmonary capillary blood volume (Vc) and alveolar-capillary conductance (Dm). Ultrasound was used to quantify "comet tails" (measure of lung fluid balance). After baseline testing, the participants had two 45 min exposures to an altitude of 8,000 ft where they breathed from gas mixtures alternating between 80/20 and 30/70 O2/N2 ratios at the required frequency (30 s, 60 s, or 120 s), separated by repeat baseline measure. Immediately and 45 min after the second exposure, baseline measures were repeated. Results: We observed no changes in Qc, Dm or Vc during the 60 s exposures. In response to the 30 s oscillation exposure, there was a significantly reduced Qc and Vc at the post-testing period (p = 0.03). Additionally, exposure to the 120 s oscillations resulted in a significant decrease in Vc at the recovery testing period and an increase in the Dm/Vc ratio at both the post and recovery period (p < 0.01). Additionally, we observed no changes in the number of comet tails. Conclusion: These data suggest "operationally-relevant" changes in inspired gas concentrations may cause an acute, albeit mild pulmonary vascular derecruitment, reduced distention and/or mild pulmonary-capillary vasoconstriction, without significant changes in lung fluid balance or respiratory gas exchange. The operational relevance remains less clear, particularly in the setting of additional environmental stressors common during flight (e.g., g forces).

Effects of Endurance Training Intensity on Pulmonary Diffusing Capacity at Rest and after Maximal Aerobic Exercise in Young Athletes.

This study compared the effects of varying aerobic training programs on pulmonary diffusing capacity (TLCO), pulmonary diffusing capacity for nitric oxide (TLNO), lung capillary blood volume (Vc) and alveolar-capillary membrane diffusing capacity (DM) of gases at rest and just after maximal exercise in young athletes. Sixteen healthy young runners (16-18 years) were randomly assigned to an intense endurance training program (IET, n = 8) or to a moderate endurance training program (MET, n = 8). The training volume was similar in IET and MET but with different work intensities, and each lasted for 8 weeks. Participants performed a maximal graded cycle bicycle ergometer test to measure maximal oxygen consumption (VO2max) and maximal aerobic power (MAP) before and after the training programs. Moreover, TLCO, TLNO and Vc were measured during a single breath maneuver. After eight weeks of training, all pulmonary parameters with the exception of alveolar volume (VA) and inspiratory volume (VI) (0.104 < p < 0889; 0.001 < ES < 0.091), measured at rest and at the end of maximal exercise, showed significant group × time interactions (p < 0.05, 0.2 < ES < 4.0). Post hoc analyses revealed significant pre-to-post decreases for maximal heart rates (p < 0.0001, ES = 3.1) and improvements for VO2max (p = 0.006, ES = 2.22) in the IET group. Moreover, post hoc analyses revealed significant pre-to-post improvements in the IET for DM, TLNO, TLCO and Vc (0.001 < p < 0.0022; 2.68 < ES < 6.45). In addition, there were increases in Vc at rest, VO2max, TLNO and DM in the IET but not in the MET participants after eight weeks of training with varying exercise intensities. Our findings suggest that the intensity of training may represent the most important factor in increasing pulmonary vascular function in young athletes.

Simultaneous Measurement of Lung Diffusing Capacity and Pulmonary Hemodynamics Reveals Exertional Alveolar-Capillary Dysfunction in Heart Failure With Preserved Ejection Fraction.

Background Hemodynamic perturbations in heart failure with preserved ejection fraction (HFpEF) may alter the distribution of blood in the lungs, impair gas transfer from the alveoli into the pulmonary capillaries, and reduce lung diffusing capacity. We hypothesized that impairments in lung diffusing capacity for carbon monoxide (DLCO) in HFpEF would be associated with high mean pulmonary capillary wedge pressures during exercise. Methods and Results Rebreathe DLCO and invasive hemodynamics were measured simultaneously during exercise in patients with exertional dyspnea. Pulmonary pressure waveforms and breath-by-breath pulmonary gas exchange were recorded at rest, 20 W, and symptom-limited maximal exercise. Patients with HFpEF (n=20; 15 women, aged 65±11 years, body mass index 36±8 kg/m2) achieved a lower symptom-limited maximal workload (52±27 W versus 106±42 W) compared with controls with noncardiac dyspnea (n=10; 7 women, aged 55±10 years, body mass index 30±5 kg/m2). DLCO was lower in patients with HFpEF compared with controls at rest (DLCO 10.4±2.9 mL/min per mm Hg versus 16.4±6.9 mL/min per mm Hg, P<0.01) and symptom-limited maximal exercise (DLCO 14.6±4.7 mL/min per mm Hg versus 23.8±10.8 mL/min per mm Hg, P<0.01) because of a lower alveolar-capillary membrane conductance in HFpEF (rest 16.8±6.6 mL/min per mm Hg versus 28.4±11.8 mL/min per mm Hg, P<0.01; symptom-limited maximal exercise 25.0±6.7 mL/min per mm Hg versus 45.5±22.2 mL/min per mm Hg, P<0.01). DLCO was lower in HFpEF for a given mean pulmonary artery pressure, mean pulmonary capillary wedge pressure, pulmonary arterial compliance, and transpulmonary gradient. Conclusions Lung diffusing capacity is lower at rest and during exercise in HFpEF due to impaired gas conductance across the alveolar-capillary membrane. DLCO is impaired for a given pulmonary capillary wedge pressure and pulmonary arterial compliance. These data provide new insight into the complex relationships between hemodynamic perturbations and gas exchange abnormalities in HFpEF.

Effects of exercise on thoracic blood volumes, lung fluid accumulation, and pulmonary diffusing capacity in heart failure with preserved ejection fraction.

Patients with heart failure with preserved ejection fraction (HFpEF) experience symptoms of exertional dyspnea that may be related to lung fluid accumulation during exercise. A computed tomography (CT)-based method was used to measure exercise-induced changes in extravascular lung fluid content and thoracic blood volumes and to determine the effect of lung fluid on lung diffusing capacity for carbon monoxide (DLCO) in stable subjects with HFpEF and healthy controls. Nine subjects with HFpEF (age = 68 ± 8 yr; body mass index = 32.1 ± 2.6 kg/m2) and eight healthy controls (62 ± 9 yr, 23.8 ± 2.4 kg/m2) performed triplicate rebreathe DLCO/DLNO (lung diffusing capacity for nitric oxide) tests in a supine position at rest and duplicate measurements during two 5-min submaximal exercise stages (15W and 35W) and recovery. Subjects subsequently performed a 5-min exercise bout (35W) inside a CT scanner, and extravascular lung fluid content and thoracic blood volumes were quantified at rest and immediately following exercise from thoracic and contrast perfusion scans, respectively. Subjects with HFpEF had a higher lung fluid content at rest compared with controls (means ± SD, HFpEF: 14.4 ± 1.7%, control: 12.8 ± 1.7%, P = 0.043) and a higher lung fluid content following exercise (15.2 ± 2.0% vs. 12.6 ± 1.5%, P = 0.009). Higher lung fluid content was associated with a lower DLCO and alveolar-capillary membrane conductance (Dm) in subjects with HFpEF (DLCO: R = -0.57, P = 0.022, Dm: R = -0.61, P = 0.012) but not in controls. Pulmonary blood volume was not altered by exercise and was similar between groups. Submaximal exercise elicited a greater accumulation of lung fluid in subjects with HFpEF compared with in controls, and lung fluid content was negatively correlated with lung diffusing capacity and alveolar-capillary membrane conductance in subjects with HFpEF.

The supine position improves but does not normalize the blunted pulmonary capillary blood volume response to exercise in mild COPD.

Patients with mild chronic obstructive pulmonary disease (COPD) demonstrate resting pulmonary vascular dysfunction as well as a blunted pulmonary diffusing capacity (DLCO) and pulmonary capillary blood volume (VC) response to exercise. The transition from the upright to supine position increases central blood volume and perfusion pressure, which may overcome microvascular dysfunction in an otherwise intact alveolar-capillary interface. The present study examined whether the supine position normalized DLCO and VC responses to exercise in mild COPD. Sixteen mild COPD participants and 13 age-, gender-, and height-matched controls completed DLCO maneuvers at rest and during exercise in the upright and supine position. The multiple FIO2-DLCO method was used to determine DLCO, VC, and membrane diffusion capacity (DM). All three variables were adjusted for alveolar volume (DLCOAdj, VCAdj, and DMAdj). The supine position reduced alveolar volume similarly in both groups, but oxygen consumption and cardiac output were unaffected. DLCOAdj, DMAdj, and VCAdj were all lower in COPD. These same variables all increased with upright and supine exercise in both groups. DLCOAdj was unaffected by the supine position. VCAdj increased in the supine position similarly in both groups. DMAdj was reduced in the supine position in both groups. While the supine position increased exercise VCAdj in COPD, the increase was of similar magnitude to healthy controls; therefore, exercise VC remained blunted in COPD. The persistent reduction in exercise DLCO and VC when supine suggests that pulmonary vascular destruction is a contributing factor to the blunted DLCO and VC response to exercise in mild COPD.NEW & NOTEWORTHY Patients with mild chronic obstructive pulmonary disease demonstrate a combination of reversible pulmonary microvascular dysfunction and irreversible pulmonary microvascular destruction.

The effect of dopamine on pulmonary diffusing capacity and capillary blood volume responses to exercise in young healthy humans.

NEW FINDINGS: What is the Central question? Does dopamine, a pulmonary vascular vasodilator, contribute to the regulation of pulmonary diffusing capacity and capillary blood volume responses to exercise and exercise tolerance? What are the main findings and their importance? Dopamine appears not to be important for regulating pulmonary diffusing capacity or pulmonary capillary blood volume during exercise in healthy participants. Dopamine blockade trials demonstrated that endogenous dopamine is important for maintaining exercise tolerance; however, exogenous dopamine does not improve exercise tolerance. ABSTRACT: Pulmonary capillary blood volume (Vc ) and diffusing membrane capacity (Dm ) expansion are important contributors to the increased pulmonary diffusing capacity (DLCO ) observed during upright exercise. Dopamine is a pulmonary vascular vasodilator, and recent studies suggest that it may play a role in Vc regulation through changes in pulmonary vascular tone. The purpose of this study was to examine the effect of exogenous dopamine and dopamine receptor-2 (D2 -receptor) blockade on DLCO , Vc and Dm at baseline and during cycle exercise, as well as time-to-exhaustion at 85% of V̇O2peak . We hypothesized that dopamine would increase DLCO , Vc , Dm and time-to-exhaustion, while D2 -receptor blockade would have the opposite effect. We recruited 14 young, healthy, recreationally active subjects ( V̇O2peak 45.8 ± 6.6 ml kg-1  min-1 ). DLCO , Vc and Dm were determined at baseline and during exercise at 60% and 85% of V̇O2peak under the following randomly assigned and double blinded conditions: (1) intravenous saline and placebo pill, (2) intravenous dopamine (2 µg kg-1  min-1 ) and placebo pill, and (3) intravenous saline and D2 -receptor antagonist (20 mg oral metoclopramide). Exogenous dopamine and dopamine blockade had no effect on DLCO , Vc and Dm responses at baseline or during exercise. Dopamine blockade reduced time-to-exhaustion by 47% (P = 0.04), but intravenous dopamine did not improve time-to-exhaustion. While dopamine modulation did not affect DLCO , Vc or Dm , the reduction in time-to-exhaustion with D2 -receptor blockade suggests that endogenous dopamine is important for exercise tolerance.

Pulmonary capillary blood volume response to exercise is diminished in mild chronic obstructive pulmonary disease.

BACKGROUND: Previous work suggests that mild chronic obstructive pulmonary disease (COPD) patients have greater lung dysfunction than previously appreciated from spirometry alone. There is evidence of pulmonary microvascular dysfunction in mild COPD, which may reduce diffusing capacity (DLCO) and increase ventilatory inefficiency during exercise. The purpose of this study was to determine if DLCO, pulmonary capillary blood volume (Vc), and membrane diffusing capacity (Dm) are diminished during exercise in mild COPD, and whether this is related to ventilatory inefficiency and dyspnea. METHODS: Seventeen mild COPD patients (FEV1/FVC: 64 ±â€¯4%, FEV1 = 94 ±â€¯11%pred) and 17 age- and sex-matched controls were recruited. Ten moderate COPD patients were also tested for comparison (FEV1 = 66 ±â€¯7%pred). DLCO, Vc, and Dm were determined using the multiple-fraction of inspired oxygen (FIO2) DLCO method at baseline and during steady-state cycle exercise at 40W, 50%, and 80% of V˙O2peak. Using expired gas data, ventilatory inefficiency was assessed by V˙E/V˙CO2. RESULTS: Compared to controls, mild COPD had lower DLCO at baseline and during exercise secondary to diminished Vc (P < 0.05). No difference in Dm was observed between controls and mild COPD at rest or during exercise. Patients with high V˙E/V˙CO2 (i.e. ≥34) had lower Vc and greater dyspnea ratings compared to control at 40W. Moderate COPD patients were unable to increase Vc with increasing exercise intensity, suggesting further pulmonary vascular impairment with increased obstruction severity. CONCLUSION: Despite relatively minor airflow obstruction, mild COPD patients exhibit a diminished DLCO and capillary blood volume response to exercise, which appears to contribute to ventilatory inefficiency and greater dyspnea.

Effects of intrathoracic pressure, inhalation time, and breath hold time on lung diffusing capacity.

The single breath hold maneuver for measuring lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO) incorporates multiple sources of variability. This study examined how changes in intrathoracic pressure, inhalation time, and breath hold time affect DLCO, DLNO, alveolar-capillary membrane conductance (DmCO) and pulmonary capillary blood volume (Vc) at rest and during submaximal exercise. Thirteen healthy subjects (mean ±â€¯SD; age = 26 ±â€¯3y) performed duplicate tests at rest and during submaximal exercise. DLCO and Vc were lower with a positive versus negative intrathoracic pressure during the breath hold at rest (DLCO: 22.2 ±â€¯5.5 vs. 22.7 ±â€¯5.5 ml/min/mmHg, p = 0.028; Vc: 46.5 ±â€¯11.6 vs. 48.2 ±â€¯11.7 ml, p = 0.018). However, during exercise, DLCO and Vc were higher with positive versus negative pressure (DLCO: 26.7 ±â€¯5.5 vs. 25.7 ±â€¯5.7 ml/min/mmHg, p = 0.014; Vc: 56.2 ±â€¯12.6 vs. 53.9 ±â€¯13.1 ml, p = 0.039). The inhalation time did not significantly affect DLCO, DLNO, DmCO or Vc. Short breath hold times (<4s) may yield high DLNO/DLCO ratios and non-physiologic DmCO values. The single breath hold maneuver is useful for evaluating gas transfer at rest and during exercise, however intrathoracic pressure, inhalation time, and breath hold time should be kept consistent between repeated tests.

The effect of aging and cardiorespiratory fitness on the lung diffusing capacity response to exercise in healthy humans.

Aging is associated with deterioration in the structure and function of the pulmonary circulation. We characterized the lung diffusing capacity for carbon monoxide (DLCO), alveolar-capillary membrane conductance (DmCO), and pulmonary-capillary blood volume (Vc) response to discontinuous incremental exercise at 25, 50, 75, and 90% of peak work (Wpeak) in four groups: 1) Young [27 ± 3 yr, maximal oxygen consumption (V̇o2max): 110 ± 18% age predicted]; 2) Young Highly Fit (27 ± 3 yr, V̇o2max: 147 ± 8% age predicted); 3) Old (69 ± 5 yr, V̇o2max: 116 ± 13% age predicted); and 4) Old Highly Fit (65 ± 5 yr, V̇o2max: 162 ± 18% age predicted). At rest and at 90% Wpeak, DLCO, DmCO, and Vc were decreased with age. At 90% Wpeak, DLCO, DmCO, and Vc were greater in Old Highly Fit vs. Old adults. The slope of the DLCO-cardiac output (Q̇) relationship from rest to end exercise at 90% Wpeak was not different between Young, Young Highly Fit, Old, and Old Highly Fit (1.35 vs. 1.44 vs. 1.10 vs. 1.35 mlCO·mmHg-1·liter blood-1, P = 0.388), with no evidence of a plateau in this relationship during exercise; this was also true for DmCO-Q̇ and Vc-Q̇. V̇o2max was positively correlated with 1) DLCO, DmCO, and Vc at rest; and 2) the rest to end exercise change in DLCO, DmCO, and Vc. In conclusion, these data suggest that despite the age-associated deterioration in the structure and function of the pulmonary circulation, expansion of the pulmonary capillary network does not become limited during exercise in healthy individuals regardless of age or cardiorespiratory fitness level.NEW & NOTEWORTHY Healthy aging is a crucial area of research. This article details how differences in age and cardiorespiratory fitness level affect lung diffusing capacity, particularly during high-intensity exercise. We conclude that highly fit older adults do not experience a limit in lung diffusing capacity during high-intensity exercise. Interestingly, however, we found that highly fit older individuals demonstrate greater values of lung diffusing capacity during high-intensity exercise than their less fit age-matched counterparts.

The blood transfer conductance for nitric oxide: Infinite vs. finite θNO.

Whether the specific blood transfer conductance for nitric oxide (NO) with hemoglobin (θNO) is finite or infinite is controversial but important in the calculation of alveolar capillary membrane conductance (DmCO) and pulmonary capillary blood volume (VC) from values of lung diffusing capacity for carbon monoxide (DLCO) and nitric oxide (DLNO). In this review, we discuss the background associated with θNO, explore the resulting values of DmCO and VC when applying either assumption, and investigate the mathematical underpinnings of DmCO and VC calculations. In general, both assumptions yield reasonable rest and exercise DmCO and VC values. However, the finite θNO assumption demonstrates increasing VC, but not DmCO, with submaximal exercise. At relatively high, but physiologic, DLNO/DLCO ratios both assumptions can result in asymptotic behavior for VC values, and under the finite θNO assumption, DmCO values. In conclusion, we feel that the assumptions associated with a finite θNO require further in vivo validation against an established method before widespread research and clinical use.

Lung function, transfusion, pulmonary capillary blood volume and sickle cell disease.

Lung function abnormalities occur in children with sickle cell disease (SCD) and may be associated with elevated pulmonary blood volume. To investigate that association, we determined whether blood transfusion in SCD children acutely increased pulmonary capillary blood volume (PCBV) and increased respiratory system resistance (Rrs5). Measurements of Rrs5 and spirometry were made before and after blood transfusion in 18 children, median age 14.2 (6.6-18.5) years. Diffusing capacity for carbon monoxide and nitric oxide were assessed to calculate the PCBV. Post transfusion, the median Rrs5 had increased from 127.4 to 141.3% predicted (p<0.0001) and pulmonary capillary blood volume from 39.7 to 64.1 ml/m2 (p<0.0001); forced expiratory volume in one second (p=0.0056) and vital capacity (p=0.0008) decreased. The increase in Rrs5 correlated with the increase in PCBV (r=0.50, p=0.0493). Increased pulmonary capillary blood volume may at least partially explain the lung function abnormalities in SCD children.

Optimizing the calculation of DM,CO and VC via the single breath single oxygen tension DLCO/NO method.

Alveolar-capillary membrane conductance (D(M,CO)) and pulmonary-capillary blood volume (V(C)) are calculated via lung diffusing capacity for carbon monoxide (DL(CO)) and nitric oxide (DL(NO)) using the single breath, single oxygen tension (single-FiO2) method. However, two calculation parameters, the reaction rate of carbon monoxide with blood (θ(CO)) and the D(M,NO)/D(M,CO) ratio (α-ratio), are controversial. This study systematically determined optimal θ(CO) and α-ratio values to be used in the single-FiO2 method that yielded the most similar D(M,CO) and V(C) values compared to the 'gold-standard' multiple-FiO2 method. Eleven healthy subjects performed single breath DL(CO)/DL(NO) maneuvers at rest and during exercise. D(M,CO) and V(C) were calculated via the single-FiO2 and multiple-FiO2 methods by implementing seven θ(CO) equations and a range of previously reported α-ratios. The RP θ(CO) equation (Reeves, R.B., Park, H.K., 1992. Respiration Physiology 88 1-21) and an α-ratio of 4.0-4.4 yielded DM,CO and VC values that were most similar between methods. The RP θ(CO) equation and an experimental α-ratio should be used in future studies.

Investigation on pulmonary diffusing capacity of the patients with diabetes mellitus / 中国综合临床

Objective To investigate pulmonary capillary changes in patients with diabetes mellitus. Meth-otis Fifty-eight patients with diabetes mellitus were enrolled and forty-seven healthy subjects were taken as control. Diffusion capacity of carbonmonoxide (DLCO) and pulmonary ventilatory function were measured. DM and Vc were measured in twenty-one patients and twelve healthy subjects among them. Results FEV1/FVC was (81.02± 6.40) % in patients with diabetes mellitus and ( 81.20±6.96 ) % in controls, and FEV 1% was ( 102.03±14.40) in patients with diabetes mellitus and 103.94±11.42 in controls ,with no significant difference between patients with DLCO% was ( 72.79±19.85 ) % in patients with diabetes mellitus and ( 90.60±13.25 ) % in controls with a sig-patients whose course of disease was less than ten years,and DLCO% was (64.69±17.49)% in patients with dia-betes mellitus whose course of disease is equal or more than ten years and (80.90±18.98)% in patients whose course of disease is less than ten years,with significant difference between these two groups (t = 4.435, -3. 381, 13.88)% in patients with diabetes mellitas and (83.58±26.79)% in controls with a significant difference (t = 4. 612, P < 0.001 ). Vc was ( 61.40±52.84 ) ml in patients with diabetes mellitus and ( 66.99±19.63 ) ml in con-trols with no significant difference (P > 0.05 ), and Vc% was (78.05±64. 40)% in patients with diabetes mellitus and (79.33±23.32) % in controls, with no significant difference ( P > 0.05 ). Conclusions Diffusing capacity is decreased in patients with diabetes mellitus, which is related to the course of disease . DM decline is the main cause of DLCO decrease in patients with diabetes mellitus.

Effects of a Basketball Activity on Lung Capillary Blood Volume and Membrane Diffusing Capacity, Measured by NO/CO Transfer in Children.

In both children and adults, acute exercise increases lung capillary blood volume (Vc) and membrane factor (DmCO). We sought to determine whether basketball training affected this adaptation to exercise in children. The purpose of this study was to determine the effects of two years sport activity on the components of pulmonary gas transfer in children. Over a 2-yr period, we retested 60 nine year old boys who were initially separated in two groups: 30 basketball players (P) (9.0 ± 1.0 yrs; 35.0 ± 5.2 kg; 1.43 ± 0.05 m), and matched non players controls (C) (8.9 ± 1.0 yrs; 35.0 ± 6.0 kg; 1.44 ± 0.06 m) who did not perform any extracurricular activity, Vc and DmCO were measured by the NO/CO transfer method at rest and during sub-maximal exercise. Maximal aerobic power and peak power output was 12% higher in the trained group compared to matched controls (p < 0.05). Nitric oxide lung transfer (TLNO) per unit lung volume and thus, DmCO per unit of lung volume (VA) were higher at rest and during exercise in the group which had undergone regular basketball activity compared to matched controls (p < 0.05). Neither lung capillary blood volume nor total lung transfer for carbon monoxide (TLCO) were significantly different between groups. These results suggest that active sport can alter the properties of the lung alveolo-capillary membrane by improving alveolar membrane conductance in children. Key PointsTrained children had greater DmCO/VA and DmCO/Vc ratios compared with control children during exercise.The mechanisms by which basketball playing children were thought to improve lung diffusion are speculative.Further work will be required to determine the kinetics of the alteration in Dm when children switch from non players to players status or vice-versa.

Pulmonary membrane diffusing capacity and pulmonary capillary blood volume in patients with stable COPD / 上海第二医科大学学报

Objective To study the clinical significance of pulmonary membrane diffusing capacity(Dm) and pulmonary capillary blood volume(Vc) in patients with stable chronic obstructive pulmonary disease(COPD). Methods Spirometry was performed in 38 patients with stable COPD and 35 healthy individuals in resting condition.The changes of pulmonary parameters were obtained and compared between groups. Results Spirometry test revealed that the percent predicted forced expired volume in one second(FEV1),FEV1/forced volume capacity(FVC)and the percent predicted maximal ventilatory volume(MVV) were declined from stage Ⅰin patients with COPD in comparison with healthy individuals,while diffusing capacity for carbon monoxide of lung(DLCO),carbon monoxide diffusing capacity per liter of alveolar(DLCO/VA),Dm and Vc were declined from stage Ⅱ.Dm in patients with COPD of stageⅠwas sig-nificantly decreased compared with the controls,while Vc was increased compared with the controls(both P

Effect of severe acute respiratory syndrome on membrane diffusing capacity and Pulmonary capillary blood volume / 解放军医学杂志

Objective To study the changes in pulmonary diffusing capacity (DL), alveolar capillary membrane diffusing capacity (Dm) and pulmonary capillary blood volume (Vc) in patients with severe acute respiratory syndrome (SARS), and to elucidate the underlying pathophysiogical mechanism of reduction of pulmonary diffusing capacity. Method Spirometry was performed in 26 SARS patients and 12 healthy individuals in resting condition. DLco were measured by single breath method, estimations of Dm and Vc were done by the method of Roughton and Forster. Results DLco in SARS patients was significantly lower than that in normal control, the same was true for Dm and Vc. The severer the pulmonary lesion, the heavier the damage to the pulmonary diffusing funetion. Conclusion The changes in Dm and Vc were both found in patients with SARS. Their measurements were helpful for detecting pulmonary involvement in SARS and defining the reason of DL abnormality in SARS. Dm and Vc were important and sensitive for monitoring pulmonary diffusing function in SARS patients