Small airways obstruction syndrome.

STUDY OBJECTIVES: To clarify the significance of a functional lung pattern characterized by a decreased vital capacity (VC) and an increased residual volume (RV), but with a normal FEV1/VC ratio. SETTING: A university teaching hospital. SUBJECTS: Patients with bronchial asthma, pulmonary emphysema, and small airways disease, and older subjects. MEASUREMENTS: Measurements of static and dynamic lung volumes, diffusing capacity of the lung for carbon monoxide (as measured by the single-breath method), nitrogen slope of the alveolar plateau, and closing volume (as measured by the single-breath O2 test). CONCLUSION: A functional pattern characterized by a decreased VC and FEV1 and increased RV, but with a normal FEV1/VC ratio and total lung capacity, reflects an obstructive impairment of small airways.     

50例健康老年人肺功能10年随访观察

目的为临床和基础研究提供健康老年人肺功能各项指标随增龄改变的参考资料。方法采用日本Ｃｈｅｓｔａｃ６５型肺功能检查仪,按常规方法进行肺功能检查。结果用力肺活量（ＦＶＣ）每年下降００３２Ｌ,第１秒用力呼气量（ＦＥＶ１）每年下降００３Ｌ,ＦＥＶ１占用力肺活量比值（ＦＥＶ１％）每年下降０１５１％,呼气流量峰值（ＰＥＦＲ）每年下降０１１８Ｌ／ｓ,最大呼气中段流量（ＭＭＥＦ）每年下降００４Ｌ／ｓ,最大通气量（ＭＶＶ）每年下降０８７６Ｌ,肺活量（ＶＣ）每年下降００４Ｌ,残气容积（ＲＶ）每年升高００３３Ｌ,功能残气量（ＦＲＣ）每年升高００３３Ｌ,残气容积／肺总量（ＲＶ／ＴＬＣ）每年升高０５９６％。戒烟组的健康老年人ＶＣ、ＦＶＣ、ＦＥＶ１、ＲＶ、ＲＶ／ＴＬＣ与从不吸烟健康老年人比较差异有显著性;不同年龄组的健康老年人肺功能下降不明显。结论肺功能各项指标随增龄而改变,健康老年人各年龄组肺功能改变不明显,吸烟对健康老年人肺功能改变有一定影响。     

Bronchodilator response in residual volume in irreversible airway obstruction

BACKGROUND: Although airway obstruction, as defined by improvement of forced expiratory volume in one second (FEV1) and/or forced vital capacity (FVC), is irreversible in patients with COPD, they clearly seem to benefit from treatment with inhaled bronchodilators. AIMS: To assess the response pattern of residual volume (RV) compared to FEV1 after bronchodilation in patients with reversible and irreversible airway obstruction. METHODS: Changes in static lung volumes were compared with improvement in dynamic lung volumes in 396 consecutive patients undergoing reversibility testing with repeat bodyplethysmography. Reversibility was defined as improvement of FEV1 >200 ml and >12% after inhalation of fenoterol hydrobromide. RESULTS: Irreversibility was found in 297 out of 396 patients with airway obstruction. Except for total lung capacity (TLC), all parameters (residual volume [RV], vital capacity [VC], forced inspiratory vital capacity [IVC], forced vital capacity [FVC], forced expiratory volume in one second [FEV1] and the FEV1/VC ratio) showed statistically significant changes after bronchodilation in 396 patients. The multiple linear regression model adjusted for age, sex and BMI showed a non-linear relationship between DeltaFEV1 or DeltaVC compared to DeltaRV after bronchodilation. If the increase in DeltaFEV1 is lower than 0.1 L, DeltaRV remains constant. However, if the increase in DeltaFEV1 is more than 0.1 L, DeltaRV decreases too. The same is found at an increase in VC of 0.3 L. CONCLUSION: In summary, in patients with irreversible airway obstruction DeltaRV cannot be predicted by DeltaFEV1 or DeltaVC after bronchodilation. Therefore, spirometric assessment should be complemented by bodyplethysmography.     

Bronchodilators increase airway instability in cystic fibrosis

Supramaximal flow transients of partial expiratory flow-volume curves are caused by a rapidly emptying compartment. By superimposing a maximal and a series of partial expiratory flow-volume curves, the volume of the flow transient equivalent for the maximal curve was estimated (volume of airway contribution = VACMEFV). This flow transient equivalent is caused by an extra dead space, created in the large airways by a full inspiration. In 18 children with cystic fibrosis (CF), routine pulmonary functions and VACMEFV were measured before and after bronchodilator medication. Baseline VACMEFV correlated directly with the curvilinearity of the flow-volume curve and inversely with the clinical and radiologic score. Significantly, bronchodilator medication improved FVC, FEV1, FEF25-75, VC, PEF, Raw, and also VACMEFV. In 6 children, VEmax25 increased as a result of apparent peripheral bronchodilation. In 3 others, end-expiratory flow increased slightly but the expanded VACMEFV included the measuring point invalidating the measurement. In the remaining 9 patients, VEmax25 decreased after bronchodilator. As an apparent discrepancy, FEV1, FVC, PEF, VC, FEF25-75 increased, and Raw decreased in 4 to 9 patients. The volumes and flow rates measured early in forced expiration and the end-expiratory flow behaved differently because VACMEFV expanded beyond the measuring points of early expiratory and mid-expiratory flow rates. As the bronchodilator rendered the compliant large airways still more distensible, the amount of air emptied from the dead space in early forced expiration increased. Simultaneously, end-expiratory flow decreased because of enhanced airway compression.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intrabreath diffusing capacity of the lung in healthy individuals at rest and during exercise

BACKGROUND: Traditional approaches to measuring the diffusing capacity of the lung for carbon monoxide (DLCO) treat the lung as a single, well-mixed compartment and produce a single value for DLCO to represent an average diffusing capacity of the lung (DL). Because DL distribution in the lung is inhomogeneous, and changes in the DL in diseased lungs may be regional, measuring regional DL, especially during exercise, may be more sensitive in detecting pulmonary vascular diseases. OBJECTIVES: To characterize regional changes in DL in healthy individuals from rest to exercise, and to provide normal references for future studies in pulmonary vascular disorders. METHODS: We reanalyzed DLCO and phase III CH(4) slopes that were obtained during a slow, single exhalation at rest and during exercise in our extended database of 105 healthy individuals. DLCO profiles between 20% and 80% of exhaled vital capacity (VC) (ie, the intrabreath DLCO) were analyzed by calculating the average DLCO measured at midlung volume (ie, 30 to 45% of exhaled VC [DLCOMLV]) and by fitting the whole curve with a third-order polynomial equation. RESULTS: DLCO decreased nonlinearly by approximately 30%, from 20 to 80% of exhaled VC at rest. DLCO during exercise was greater than that at rest, and the increase was similar at all lung volumes. The CH(4) slopes at rest and during exercise were similar. Prediction equations based on regressions on age, sex, and height were computed for resting and exercise DLCOMLV and the phase III CH(4) slope (an index of ventilation distribution). CONCLUSIONS: Capillary recruitment/dilation during exercise in healthy individuals is a uniform process throughout the lungs. Our analyses provide a database for a noninvasive method that can incorporate exercise to evaluate the volume-dependent distribution of DLCO in lung diseases.     

A normal FEV1/VC ratio does not exclude airway obstruction

BACKGROUND: A decreased forced expiratory volume in 1 s/vital capacity (FEV(1)/VC) ratio is the hallmark of the definition of airway obstruction. We recently suggested that a lung function pattern, we called small airways syndrome (SAOS), has a normal FEV(1)/VC and total lung capacity (TLC) and reflects obstruction of small airways. OBJECTIVES: To substantiate our hypothesis we measured and compared lung function tests including maximal expiratory flow rates (MEFR), sensitive indicators of airway obstruction, in SAOS subjects and in matched controls. METHODS: We selected 12 subjects with the pattern of SAOS, but without chronic lung or heart disease (average age: 40.7 +/- 7.8 years) and 36 age-matched subjects with normal lung function (42.8 +/- 6.3 years). We measured static and dynamic lung volumes, MEFR and lung diffusing capacity (DL(CO)). RESULTS: SAOS subjects were heavier smokers (p < 0.05) and body mass index was less than in control subjects (p < 0.01). Both FEV(1)/VC ratio and TLC were comparable in the two groups. However, FEV(1), VC, DL(CO), and MEFR were lower and residual volume (RV) and RV/TLC ratio were higher (p < 0.05) in the SAOS group than in the control one. Furthermore, the MEFR curve of the SAOS group was displaced to the left without any change in slope, suggesting premature airway closure. CONCLUSION: Our results suggest that a normal FEV(1)/VC ratio does not exclude airway obstruction. A decrease of FEV(1), provided TLC is normal, reflects small airway obstruction.     

Lung involvement in essential mixed cryoglobulinemia.

Lung function studies were performed in 23 patients with the syndrome of essential mixed cryoglobulinemia. Signs of exposure to hepatitis B virus were present in nine (HBV+) and absent in 14 (HBV?). Pulmonary symptoms were generally absent or moderate except in three patients who presented with either asthma, hemoptysis or pleurisy together with the other manifestations of the disease. On the contrary, tests indicative of small airways disease, such as forced end-expiratory flow (FEF_0.75-0.85VC) and maximal expiratory flow at low lung volume (Vmax_0.75VC) were markedly altered (61.9 per cent and 40.4 per cent of the expected values, respectively). Other lung function tests, such as residual volume (RV), airway resistance (Raw), FEF_0.25-0.75VC, maximal expiratory flow at 50 per cent vital capacity (VC)(Vmax_0.50VC) showed smaller deviations from normal, whereas vital capacity (VC), total lung capacity (TLC), forced expiratory volume in 1 second (FEV₁), FEV₁:VC, RV:TLC and intrathoracic gas volume (ITGV) were within the normal limits. Nine of 14 of the HBV? patients showed impairment of gas exchange, measured as alveoloarterial oxygen gradient D(A-a)O₂, which, on the contrary, was always within normal limits in the nine HBV+ patients. The difference between the two groups was significant (28.4 mm Hg and 18.6 mm Hg, respectively, p < 0.025). Roentgenographic signs of interstitial lung involvement were present in 18 of 23 patients. Lung scan showed, in all instances in which it was performed, inhomogeneities of regional lung perfusion; they were, however, minimal in nearly half of the cases. The present data indicate that lung involvement is frequent in essential mixed cryoglobulinemia, that it should be recognized in addition to the other features of the disease and that it seems to be more pronounced in the HBV? patients. Indirect evidence suggests that circulating immune complexes may play a role in the genesis of the lung abnormalities observed in these patients.     

Enhanced responses to aerosolized bronchodilator therapy in asthma using respiratory maneuvers.

To determine if respiratory maneuvers may enhance the response to inhaled bronchodilator drugs, we evaluated the bronchodilator responses when isoproterenol was: inhaled as a bolus high (80 percent VC) compared to low (20 percent VC) lung volumes, and inhaled as a single 800 microgram dose compared to four 200 microgram doses given 20 min apart. Nine asthmatic subjects inhaled isoproterenol sequentially at high and low lung volumes on two separate days; 15 others inhaled single doses of 200, 400, 600, and 800 microgram isoproterenol on four separate days. FEV1, specific conductance (Gaw/VL), Vmax50%, and the slope of phase 3 of the single-breath nitrogen test (deltaN2/L) were measured 10 min after each dose. FEV1 and Gaw/VL increased and deltaN2/L decreased more following inhalation at high compared to low lung volume (P less than 0.05). Gaw/VL increased more in the group given 800 microgram in divided doses than the group given a single dose (P less than 0.05). These findings suggest that the bronchodilator response to isoproterenol may be enhanced by inhaling the drug in divided doses sequentially and by delivering the drug near maximal inspiration. An enhanced response after the latter maneuver may be due to more uniform distribution of the drug to airway receptor sites.     

Glottic dimensions in healthy men and women

Glottic aperture is important in modulating respiratory system resistance. Male patients with obstructive sleep apnea (OSA) have a smaller glottic cross-sectional area compared to controls. Since OSA has a strong male predominance, we reasoned that glottic dimensions may differ between healthy men and women. Therefore, we utilized the acoustic reflection to measure glottic cross-sectional area in 44 non-smoking, non-obese, healthy subjects, 25 men and 19 women. Glottic area was measured during a continuous slow expiration from total lung capacity (TLC) to residual volume (RV). We compared glottic areas in men and women at three lung volumes: TLC, 50% of vital capacity (VC), and RV. We found that in all but 2 subjects, glottic areas at TLC was greater than at 50% VC or RV. At any given lung volume, there was no significant difference in glottic area between men and women. The reduction in glottic area between TLC and RV was also similar between men and women (36 +/- 24% and 33 +/- 21%, respectively). However, this reduction in glottic area occurred mainly at low lung volumes in women, and more uniformly throughout the vital capacity range in men. We conclude that changes in glottic dimensions are dependent on lung volume, that healthy men and women have similar glottic areas, and that the glottic aperture shows similar variation with lung volume among both sexes.     

Effects of noradrenaline and isoproterenol on cardiopulmonary function in a canine model of acute pulmonary hypertension

The authors investigated acute cardiopulmonary effects of noradrenaline and isoproterenol infusion in a canine model of increased pulmonary vascular resistance (PVR) and decreased cardiac output (CO). In six anesthetized, ventilated dogs, autologous blood clots were injected over approximately two hours to increase right ventricular (RV) afterload and decrease CO. After CO had decreased 40 percent dogs were treated with noradrenaline or isoproterenol in alternate sequence. Both drugs increased stroke volume but only isoproterenol affected CO. Flow increased from 1.3 to 3.0 L X min-1 (p less than .01) with isoproterenol infusion. Corresponding to the increase in CO, RV filling pressure and PVR decreased, from 9 to 5 mm Hg, and from 36 to 16 mm Hg X L-1 X min (p less than .01) respectively. When a moderate decrease in CO complicates an acute increase in PVR, isoproterenol may be an excellent drug to treat the decrease in flow.     

Relation between transpulmonary pressure and right ventricular isovolumetric pressure change during respiratory support

Simultaneous recordings of airway pressure, pleural pressure, and right ventricular (RV) pressure were obtained during mechanically controlled ventilation in a group of patients requiring respiratory support. Changes in transpulmonary pressure (calculated as airway pressure minus pleural pressure) were measured at end-expiration and end-inspiration during intermittent positive pressure ventilation with or without the application of a positive end-expiratory pressure, and were related to RV isovolumetric pressure changes at the onset of systole. It was found that any increase in transpulmonary pressure by intermittent positive pressure ventilation, or positive end-expiratory pressure (PEEP), or both, was associated with a proportional increase in RV isovolumetric pressure change. Moreover, when lung volume was progressively increased by incremental increases in tidal volume or PEEP level, transpulmonary pressure and RV isovolumetric pressure changes were strongly and linearly correlated. These results suggest that: 1) RV isovolumetric pressure change might be used as an index of RV output impedance during respiratory support by mechanically controlled ventilation; and 2) lung inflation resulting from the use of a positive airway pressure during respiratory support can increase RV output impedance and thereby contribute to the decrease in RV stroke output.     

Effect of unsupported arm exercise on ventilatory muscle recruitment in patients with severe chronic airflow obstruction

We have proposed that unsupported arm exercise alters ventilatory muscle recruitment and precipitates dyspnea in patients with severe chronic airflow obstruction (CAO). To test this hypothesis, we studied 11 patients with CAO during symptom-limited, unsupported arm exercise (UAE) and compared it with supported arm cycling (SAE). During each exercise period, we recorded endoesophageal (PpI), gastric (Pg), and transdiaphragmatic (Pdi) pressures along with heart rate, respiratory rate, and endurance time. Expired gas was collected to determine oxygen uptake (VO2) and minute ventilation (VE). Exercise endurance was shorter for UAE than for SAE (210 +/- 114 versus 270 +/- 120 s, p less than 0.05), even though peak exercise heart rate (113 +/- 5 versus 122 +/- 7 beats/min, p less than 0.05), VO2 (5.9 +/- 0.5 versus 7.1 +/- 0.8 ml/kg/min, p less than 0.05) and VE (16.5 +/- 1.2 versus 19.8 +/- 1.3 L/min, p less than 0.05) were lower for UAE. Mean (+/- SD) values for changes in pleural (delta PpI) and gastric (delta Pg) pressures during either type of arm exercise were significantly greater than at rest (p less than 0.02). In eight of 11 patients during UAE, the changes between end-inspiratory and end-expiratory transdiaphragmatic pressure (delta Pdi) were observed to develop in a similar pattern. In these patients, end-inspiratory Pg was more positive and end-inspiratory PpI was less negative during UAE than during SAE (p less than 0.02). In addition, PpI at end expiration was markedly positive when performing UAE (p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)     

Sampling of exhaled nitric oxide in children: end-expiratory plateau, balloon and tidal breathing methods compared.

The aim of this study was to compare exhaled nitric oxide concentrations obtained during controlled slow exhalation, presently considered as the method of choice, with two sampling methods that are easily performed by children: blowing air into a balloon and tidal breathing through a mouthpiece. One hundred and one well controlled, stable allergic asthmatic children (median age 11.7 yrs) performed the following tasks in duplicate: 1) exhalation from total lung capacity through a mouthpiece against a resistor with a standardized flow rate of 20% of the subject's vital capacity per second, using a biofeedback system; 2) a single deep exhalation into an NO-impermeable mylar balloon; and 3) tidal breathing through a low resistance mouthpiece over 2 min. NO was measured using a chemiluminescence analyser. Twenty-nine children (29%) were not able to perform a constant-flow exhalation of at least 3 s. All children performed the balloon and tidal breathing methods without difficulty. NO concentrations (means +/-SEM) were 5.3+/-0.2 parts per billion (ppb) at the end-expiratory plateau, 5.2+/-0.3 ppb in balloons (intraclass correlation coefficient (r(i)) = 0.73) and 8.0+/-0.4 ppb during tidal breathing (p<0.001, r(i) = 0.53 compared to plateau values). Mean values of NO during tidal breathing increased significantly with time, suggesting increasing contamination with nasal air. It was concluded that, in asthmatic children, the end-expiratory plateau concentration of nitric oxide during exhalation at 20% of the vital capacity per second is similar to the values obtained with the balloon method, with satisfactory agreement, but differs from values obtained during tidal breathing. The balloon method is cheap, simple and offers the interesting possibility to study exhaled nitric oxide in young children independently of the presence of a nitric oxide analyser.     

Assessment of right ventricular function by strain rate imaging in chronic obstructive pulmonary disease.

The purpose of the current study was to compare right ventricular (RV) myocardial wall velocities (tissue Doppler imaging) and strain rate imaging (SRI) parameters with conventional echocardiographic indices evaluating RV function in chronic obstructive pulmonary disease (COPD) patients. In total, 39 patients with COPD and 22 healthy subjects were included in the current study. Seventeen patients had pulmonary artery pressure <35 mmHg (group I) and 22 patients had pulmonary artery pressure >35 mmHg (group II). Tissue Doppler imaging, strain and strain rate (SR) values were obtained from RV free wall (FW) and interventricular septum. Respiratory function tests were performed (forced expiratory volume in one second/vital capacity (FEV(1)/VC) and carbon monoxide diffusion lung capacity per unit of alveolar volume (D(L,CO)/V(A))). Strain/SR values were reduced in all segments of group II patients compared with group I patients and controls with lowest values at basal FW site. A significant relationship was shown between peak systolic SR at basal FW site and radionuclide RV ejection fraction. A significant relationship was shown between peak systolic SR at basal FW site and D(L,CO)/V(A) and FEV(1)/VC. In conclusion, in chronic obstructive pulmonary disease patients, strain rate imaging parameters can determine right ventricular dysfunction that is complementary to conventional echocardiographic indices and is correlated with pulmonary hypertension and respiratory function tests.     

Restrictive impairment in patients with asthma

BACKGROUND: Patients with asthma have intermittent or persistent airflow obstruction, most often manifested spirometrically by reduced forced expiratory volume in 1s (FEV(1)) and FEV(1)/vital capacity (VC) ratio. In some patients, the VC may be reduced by air trapping, with an increase in functional residual capacity (FRC) and residual volume (RV) (pseudorestriction). We have reported 12 asthmatic patients with reduced VC and no increase in RV, i.e., a true restrictive impairment [Gill et al. True restrictive impairment in bronchial asthma. Am J Respir Crit Care Med 1999:159:A652]. OBJECTIVES: To confirm previous observations of true restrictive impairment (not attributable to air trapping) in patients with asthma, and to estimate its frequency in an asthmatic population. METHODS: Review of pulmonary function tests and clinical records of all post-pubertal patients diagnosed as asthma between January 2000 and September 2003 in a 184 bed inner city teaching hospital in Jamaica, Queens, New York. The clinical diagnosis of asthma was accepted when one or more of the following pulmonary function criteria were met: Positive bronchodilator response (BD), positive methacholine, repeated variability in spirometric values. Restriction was defined as decrease in total lung capacity (TLC) or decrease in VC with no increase in functional residual capacity (FRC) plus normal or high FEV(1)/FVC ratio. Patients with any clinical finding consistent with restriction, including a decreased diffusing capacity (DL) or obesity (BMI >30) were excluded. RESULTS: A total of 100 of 413 (24%) patients with asthma had restriction; 21 of these met all exclusions (including DL and BMI) and 11 (of 46) patients with an increased BMI and normal DL normalized their FVC on BD therapy, demonstrating that their pre-BD restrictive impairment could not be attributed to obesity. Plethysmographic FRC was measured in 81 of the 100 patients with restriction and was increased in only seven. CONCLUSION: True restrictive impairment was noted in at least 32 of 413 asthmatics (8%), consistent with previous observations in asthma and reactive airways dysfunction syndrome. This finding is not widely recognized and should not preclude the diagnosis of asthma, BD testing or appropriate therapy for asthma.     

Breathing pattern affects airway wall temperature during cold air hyperpnea in humans

We studied the influence of flow rate on respiratory heat exchange in 9 healthy adult subjects using a new noninvasive technique, the single-breath temperature washout (SBTW) curve. The SBTW curve is a plot of exhaled gas temperature versus exhaled volume during a standard exhalation and consists of an initial rise (within the first 200 ml) to a plateau temperature that persists through the remainder of exhalation. We found that exhaled gas temperatures within the initial expirate were colder at every airway locus than corresponding intra-airway gas temperatures at end-inspiration, suggesting that heat exchange occurs between lumenal gas and the relatively cooler airway walls during exhalation. The SBTW plateau temperatures were: (1) lower after preconditioning the airways with rapid (80 L/min) isocapnic hyperpnea of frigid air than after less rapid (40 L/min) cold-air hyperpnea or after quiet breathing; (2) lower when, after identical airway preconditioning regimens, the SBTW exhalation was performed with a slower (0.5 versus 2.5 L/s) expiratory flow; and (3) lower when SBTW curves were obtained after airway preconditioning using respiratory patterns with larger inspiration-expiration duration (I:E) ratios (5:1 versus 1:5) at fixed minute ventilation and respiratory rate. Our results indicate that the global respiratory gas-wall heat transfer coefficient increases with velocity to the 0.9 power, a finding similar to that in previous studies of turbulent flow in rigid pipes.     

Lung volume dependence of pharyngeal cross-sectional area in patients with obstructive sleep apnea

We examined the relationship between lung volume and pharyngeal cross-sectional area in 9 obese patients with obstructive sleep apnea and 10 age-matched, obese subjects without sleep apnea. Pharyngeal area was measured in the upright, seated posture using an acoustic reflection technique. Measurements were made at a rate of 5 per second during a slow exhalation from total lung capacity (TLC) to residual volume (RV). In the control subjects, the mean +/- SE pharyngeal area was 5.6 +/- 0.2 cm2 at TLC, and decreased by 30 +/- 5% over the vital capacity range to 3.9 +/- 0.3 cm2 at RV. In contrast to the control subjects, in patients with obstructive sleep apnea, pharyngeal area was 5.0 +/- 0.2 cm2 at TLC, and decreased by 54 +/- 6% over the vital capacity range to 2.3 +/- 0.3 cm2 at RV. The difference in pharyngeal area between the patients and control subjects was significant at all lung volumes below TLC, as was the difference in the magnitude of change in pharyngeal area with change in lung volume. The results indicate that in obese patients with obstructive sleep apnea, pharyngeal cross-sectional area is abnormally small, and varies considerably with changes in lung volume. The beneficial effects of weight reduction in such patients may relate to the coincident increase in functional residual capacity, causing an increase in upper airway size.     

LUNG FUNCTION AND RESPIRATORY MUSCLE STRENGTH AFTER PROPRANOLOL IN THYROTOXICOSIS

Thirty-five thyrotoxic patients were assessed before treatment, after treatment with propranolol, and after antithyroid drugs. The first group of patients ( n = 17) performed the following tests at all three assessment points: forced expiratory volume in the first second (FEV,), vital capacity (VC), functional residual capacity (FRC), residual volume (RV), total lung capacity (TLC), maximal mid-expiratory flow rate (MMFR), diffusing capacity for carbon monoxide (DLCO), and maximum static inspiratory and expiratory mouth pressures (Plmax and PEmax). Arterial blood gas analysis was also performed for the first group of patients. No significant changes were seen either after propranolol or after antithyroid drugs in the FRC, RV, TLC, MMFR, DLCO, or blood gases. The remaining 18 patients, group 2, performed only the FEV₁, VC, Plmax, and PEmax tests at each assessment. The only index of respiratory function that improved significantly after propranolol was Plmax (from 46.5 ± 16.5 to 53.2 ± 22 cmH₂O, p < 0.01). This suggests that adrenergic excess may play a role in thyrotoxic inspiratory muscle weakness. After antithyroid drugs, Plmax, PEmax, FEV₁, and VC all increased significantly as expected. (Aust NZ J Med 1986; 16: 496–500.)     

Lung mechanics and their relationship to lung volumes in pulmonary sarcoidosis

Pulmonary sarcoidosis was studied with respect to lung mechanical properties and to the influence of these on lung volumes. Sixty-six patients, with histological support for the diagnosis of sarcoidosis, and radiological signs of pulmonary involvement, i.e., stage II or III, were studied. The static pressure/volume (P/V) curves showed that the static elastic recoil pressure (PelL) tended to be increased at a given percentage of predicted total lung capacity (TLC). Reduction of static lung compliance (CstL) was a typical finding. At maximal inspiration PelL was abnormally low in 20 subjects, including in the main those with recent onset of the disease and older patients. The possibility of a greater inflammatory activity at the site of mechanical receptors in the lungs and airways of these patients is proposed. Pulmonary resistance, measured at a given PelL, was usually increased signifying bronchial involvement. TLC, residual volume (RV) and functional residual capacity (FRC) were lower in current smokers and ex-smokers than in lifelong nonsmokers. This may be due to synergistic effects of the inflammatory processes caused by smoking and sarcoidosis. A reduced vital capacity (VC) mainly reflected a low CstL but also obstruction with increased RV. Forced expiratory volume in one second (FEV1) reflected lung stiffness and obstruction equally. Lung mechanics revealed functional abnormalities which were not obvious from the standard tests, particularly in patients with respiratory symptoms.     

Respiratory function in children undergoing bone marrow transplantation.

We conducted a prospective study of respiratory function in children undergoing bone marrow transplantation (BMT) for onco-hematological disorders. Each child was evaluated before and 100 days after BMT. The investigations included clinical examination, chest X-ray, and pulmonary function tests (PFT) to determine: slow vital capacity (VC), functional residual capacity (FRC), total lung capacity (TLC), forced expiratory volume in 1 s (FEV1), carbon monoxide diffusing capacity (DLCO), ratio of residual volume (RV) to TLC, and FEV1/VC. The values obtained before and after BMT were compared to predicted values, and the post-BMT values were compared to the pre-BMT values (Student's t-test). From 1986 to 1995, 77 children underwent BMT, of whom 39 were available for testing. The pre-BMT VC (P = 0.0234) and DLCO (P < 0.0001) were lower and FRC higher (P < 0.0001) than predicted values. After BMT, the VC (P = 0.004), TLC (P = 0.044), and FEV1 (P = 0.012) were lower, and the RV/TLC ratio was higher (P = 0.043), compared with pre-BMT data. The observed respiratory abnormalities were not clinically relevant. The only identifiable risk factor for a decrease in lung function was age at BMT. This study shows that some lung dysfunction may be present before BMT and be further altered by BMT. This stresses the need for longitudinal respiratory monitoring and follow up to detect such dysfunctions and to insure an optimal treatment program for these children.