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PubMed1998

[Lung volumes in non-smoking healthy men in Maracaibo, Venezuela].

The significant applicability of the tests to measure lung volumes makes it necessary to handle them frequently and this implies the comparison of the registered values for lung function parameters with predicted or referential values which are obtained via derivate equations of healthy population studies. The Slow Vital Capacity (SVC), Inspiratory Capacity (IC), Functional Residual Capacity (FRC), Residual Volume (RV), Total Lung Capacity (TLC) and the physical characteristics, were measured in 50 healthy men, non smokers, with ages between 17 and 63 years, in order to deduce++ prediction equations. The functional tests were performed by means of the multiple respiratory technique and Helium Dilution, using a Spinnaker TL Lung Functions Analyzer. Stepwise multiple regression analyses were used to derive equations for predicting lung volumes, that allowed the inclusion of the variables that add prediction with statistical significance (95% of confidence), and obtaining for SVC: R = 0.853, SEE = 0.350 lts; IC: R = 0.822, SEE = 0.296 lts; FRC: R = 0.843, SEE = 0.326 lts; RV: R = 0.891, SEE = 0.153 lts y TLC: R = 0.883, SEE = 0.458 lts. The analysis of variance (ANOVA) was highly significant (p < 0.00001) for each one of the models of regression of the estimated parameters. The fifth percentile was considered as the lower limit of the established volume as the normal value. The calculation of fifth percentiles determined were SVC = 3.59 lts, IC = 2.47 lts, FRC = 2.14 lts, RV = 1.26 lts, and TLC = 4.88 lts. Those values can represent the levels under which the test are considered as reduced. Values which are equal o greater can be considered as "normal" for each one of the parameters studied. The equations of prediction for the SVC, IC, FRC, RV and TLC can be utilized with validity and high confidence to calculate reference static lung volumes in our population (p < 0.00001).

Adolescent↗
PubMed1981

Pulmonary mechanisms of the normal ferret.

Pulmonary mechanics were measured in normal anesthetized male Fitch ferrets (200-360 g). In eight transorally intubated ferrets, pressure-volume (PV) curves for the lung and chest wall were obtained with an esophageal balloon and body plethysmograph. The lung volumes and capacities expressed as a percentage of the total lung capacity (mean, 49.8 ml) were: vital capacity, 84.7%; inspiratory capacity, 63.7%; inspiratory reserve volume, 58.2%; functional residual capacity, 33.8%; expiratory reserve volume, 16.8%; residual volume, 15.3%; and tidal volume, 8.0%. The compliance of the lung (2.93 ml . cmH2O-1), chest wall (22.42 ml . cmH2O-1) and respiratory system (2.55 ml . cmH2O-1) were determined from the PV curves. The dynamic compliance (1.6 ml . cmH2O-1), pulmonary resistance (0.024 cmH2O . ml-1 . s), frequency of breathing (43.5 breaths . min-1), and minute ventilation (195 ml . min-1) were measured during spontaneous breathing. In a second group of 10 ferrets the total airway resistance (0.116 cmH2O . ml-1 . s) and specific conductance (0.915 ml . s-1 . cmH2O . ml-1) were measured during spontaneous nasal breathing. In general the pulmonary mechanics of the ferret were similar to those of the rabbit and dog, when the data were normalized for lung volume.

Airway Resistance↗
PubMed1996

Lung volumes and pressure-volume relations of the respiratory system in small ventilated neonates with severe respiratory distress syndrome.

Total lung capacity (TLC), inspiratory capacity (IC), functional residual capacity (FRC), and deflation pressure-volume (P-V) curves were studied in 16 intubated neonates (540-3300 g), 10 with severe respiratory distress syndrome (RDS) and 6 air-ventilated with normal chest radiograms. FRC was measured using washout of a tracer gas (sulfur hexafluoride), and TLC and IC were calculated after inflating the lungs to 30 cm H2O. P-V curves were obtained during expiration from TLC using an interrupter technique, and the steepest slope of the curve, i.e. the maximum compliance (Crs-max), was calculated. In addition, an index of ventilation inhomogeneity (pulmonary clearance delay, PCD) was computed from the shape of the SF6 washout curve. TLC/body weight was less in the RDS group than in the air-ventilated group (median 19 and range 16-43 mL/kg versus 48 and 43-52 mL/kg, respectively; p < 0.01), mainly because of a marked reduction in IC (median 11 and range 8-24 mL/kg versus 29 and 28-40 mL/kg; p < 0.01). The flatter P-V curve in the RDS group was reflected also in a lower Crs-max (median 0.7 and range 0.4-1.7 cm H2O-1 kg-1) than in the air-ventilated group (2.3 and 2.0-3.1 mL cm H2O-1 kg-1, respectively; p < 0.01). Thus, there was no overlap in IC or Crs-max between the groups, suggesting that reductions in these measures may be main characteristics of RDS. On the other hand, no difference in PCD was found, indicating that, in infants with RDS, the tidal volume is distributed fairly homogeneously to the ventilated parts of the lungs.

Functional Residual Capacity↗
PubMed1975

Effects of expiratory threshold loading during steady-state exercise.

Increases in functional residual capacity (FRC) decrease inspiratory muscle efficiency; the present experiments were designed to determine the effect of FRC change on the ventilatory response to exercise. Six well-trained adults were exposed to expiratory threshold loads (ETL) ranging from 5 to 40 cmH2O during steady-state exercise on a bicycle ergometer at 40-95% VO2max. Inspiratory capacity (IC) was measured and changes of IC interpreted as changes of FRC. ETL did not consistently limit exercise performance. At heavy work (greater than 92% VO2max) minute ventilation decreased with increasing ETL; at moderate work (less than 58% VO2max) it did not. Decreases in ventilation were due to decreases in respiratory frequency with prolongation of the duration of expiration being the most consistent change in breathing pattern. At moderate work levels, FRC increased with ETL; at maximum work it did not. Changes in FRC were dictated by constancy of tidal volume and a fixed maximum end-inspiratory volume of 80-90% of the inspiratory capacity. When tidal volume was such that end-inspiratory volume was less than this value, FRC increased with ETL. Mouth pressure measured during the first 0-1 s of inspiratory effort against an occluded airway (P0-1) was increased by ETL equals 30 cmH2O, in spite of the fact that ventilation was decreased. We concluded that changes in FRC due to ETL had no effect on the ventilatory response to exercise and that changes in P0-1 induced by ETL did not reflect changes of inspiratory drive so much as changes of the pattern of inspiration.

Adult↗
PubMed1990

Influence of lung volume on sympathetic nerve discharge in normal humans.

The purpose of this study was to determine the influence of tidal volume, breathing pattern, and beginning lung volume on the modulation of efferent, muscle sympathetic nerve activity (MSNA) in humans. In seven supine, healthy subjects, we measured MSNA (microneurography of the right peroneal nerve) and beat to beat arterial blood pressure during 1) low-frequency breathing (fb = 12 breaths/min) at tidal volumes (VT) of 30% (control), 50%, and 70% of inspiratory capacity and with inspiratory time-to-total breath time ratios (TI/TTOT) of 0.3-0.5 (control), less than 0.3, and greater than 0.5; and 2) simulated exercise hyperpnea (fb = 40 breaths/min; VT = 60-70% inspiratory capacity; minute ventilation, approximately 90 1). To optimize our ability to discern modulatory effects, breathing was performed during three conditions of heightened MSNA: nonhypotensive (less than 20 mm Hg) lower-body negative pressure, isometric handgrip exercise, and posthandgrip vascular occlusion (ischemia). PETCO2 was maintained at normal levels by adjusting the FICO2. Within-breath modulation of MSNA was observed during control tidal breathing with approximately 65% of the burst frequency occurring during the expiratory phase. Deep, low-frequency breathing potentiated this modulatory influence (p less than 0.05 versus control) and produced near-complete sympathoinhibition from onset-mid inspiration to early-mid expiration. Increasing (slow inspiration) and decreasing (fast inspiration) TI/TTOT shifted the onset of sympathoinhibition occurring later (greater change in volume) and earlier (less change in volume) during inspiration, respectively. In two subjects who performed deep breathing from an elevated beginning lung volume, the sympathoinhibition was observed earlier in the inspiratory period and with less change in volume compared with control. These within-breath modulatory effects did not appear to be due solely to changes in arterial pressure. Sustained low- or high ("exerciselike")-frequency deep breathing did not alter total minute MSNA compared with control breathing. These results demonstrate that the depth and pattern of breathing, and possibly the starting lung volume, exert marked influences on the within-breath modulation of MSNA in humans. Our findings also suggest that these modulatory effects may be mediated, at least in part, by pulmonary stretch reflexes.

Adult↗
PubMed2005

Preoperative predictors of prolonged postoperative mechanical ventilation in children following scoliosis repair.

Scoliosis is associated with progressive restrictive lung disease and an increased risk of pulmonary complications following surgical correction. Identification of higher risks for prolonged postoperative mechanical ventilation (MV) improves postoperative care. Our objective was to determine if preoperative pulmonary function tests (PFT) predict prolonged postoperative MV (defined as MV >or=3 days). We correlated preoperative PFT (forced expired volume in 1 sec, FEV1; vital capacity, VC; inspiratory capacity, IC; maximal inspiratory pressure, MIP; total lung capacity, TLC; and residual volume, RV) and postoperative MV days in 125 patients who had scoliosis surgery (aged 13.7 +/- 3.0 (SD) years) from January 1990-July 2001. We had 71 male and 54 female patients. Scoliosis types were 13 congenital, 27 idiopathic, 57 neuromuscular, 23 syndrome/tumor, and 5 kyphoscoliosis. Forty patients (32%) had postoperative MV >or=3 days. Independent factors likely requiring postoperative MV >or=3 days were neuromuscular scoliosis (P < 0.001) and FEV1 <40% predicted. Independent factors most likely were: neuromuscular scoliosis with preoperative FEV1 <40% predicted (P < 0.01). Independent factors most unlikely were: idiopathic scoliosis (P < 0.002). VC <60% predicted, IC <30 ml/kg, TLC <60% predicted, and MIP <60 cm H2O correlated with postoperative MV >or=3 days (P < 0.05). We found no association between RV and postoperative MV. FEV1 <40% predicted, VC <60% predicted, IC <30 ml/kg, TLC <60% predicted, MIP <60 cm H2O, and neuromuscular disease each correlated with prolonged postoperative MV. Neuromuscular disease or a preoperative FEV(1) <40% predicted were more likely, and older children with neuromuscular disease and FEV1 <40% predicted were most likely to require prolonged postoperative MV (P < 0.01). Clearly FEV1, and possibly VC, IC, TLC, and MIP, may increase accuracy in predicting the need for prolonged postoperative MV.

Adolescent↗
PubMed1979

Pulmonary reaction to upper mantle radiation therapy for Hodgkin's disease.

To study the effects of upper mantle radiation therapy on pulmonary function, forced expiratory volume in one second (FEV1), vital capacity (VC), inspiratory capacity (IC), diffusing capacity for CO (DLCO) and diffusion per unit of alveolar volume (DL/VA were determined in 28 patients with Hodgkin's disease, stages 1--3, before therapy and at regular intervals thereafter. Within the first year of follow-up there were significant declines in DLCO, VC, and IC, whereas there were no significant changes in FEV1 or DL/VA. DLCO showed the greatest decline in the largest number of subjects (22/28). Eleven of the 22 had 20 to 60 percent decline of DLCO from baseline. The maximum mean decline in DLCO was -12.7 +/- 3 percent at the 87th +/- 3 days from initiation of therapy postradiation sustained through the 150th day and improving to pretreatment value (+/- 5 percent) by the 8th to 12th month. The changes in DLCO seemed to be independent of the radiation dose ranges evaluated, clinically apparent intrathoracic lymphoma, postradiation radiographic abnormalities and respiratory symptoms. We concluded that impairment in diffusing capacity and loss of vital capacity will develop in most patients receiving upper mantle radiation therapy, indicating that pulmonary reaction occurs despite lung shielding. The functional losses were prolonged and occasionally severe, but were transient and subclinical in most but not all cases. A case of fatal radiation pneumonitis affecting the lung beyond the field of irradiation is reported.

Adolescent↗
PubMed2004

Comparison of oral and depot intra-muscular steroids in assessing steroid-responsiveness in COPD.

Non-compliance or euphoria may limit the usefulness of prednisolone tablets in assessing steroid-responsiveness in chronic obstructive pulmonary disease (COPD). Depot intra-muscular methyl-prednisolone (imMP), producing a plateau steroid effect over two weeks, may be more reliable. Following two weeks of placebo, twenty-seven COPD patients (mean FEV 1 43% predicted) participated in a two-week randomised, double-blind, placebo-controlled, parallel-design trial taking either 120 mg imMP with placebo tablets or placebo injection with prednisolone 30 mg daily. After each period, post-bronchodilator FEV 1, forced vital capacity (FVC), inspiratory capacity (IC) and six-minute walking distance (6MWD) were assessed and patients completed both quality-of-life scores (St. George's 30 and Short Form 36) and mood scores (Hospital Anxiety and Depression scores and Altman's Self-rating Mania Scale). There were no significant changes in 6MWD, quality of life or mood scores after either type of steroids and no change in lung function after imMP. By contrast, there were small mean improvements in lung function on oral prednisolone (mean FEV 1, FVC and IC increased by 100, 320 and 150 ml, respectively). Only the improvement in FVC was significantly greater after prednisolone compared with imMP. Single depot intra-muscular injections of steroids have no advantage over oral daily prednisolone in testing steroid-responsiveness in COPD patients.

Administration, Oral↗
PubMed2001

Does the mode of inhalation affect the bronchodilator response in patients with severe COPD?

Spacing devices improve lung deposition of aerosols from metered dose inhalers (MDI) but it is sometimes difficult for dyspnoeic patients to perform maximal breaths with breath-holds needed to inhale the aerosols from them. Our aim was to determine whether the response to bronchodilators (BD) depended on the method of inhalation. We studied 20 patients with moderately severe chronic obstructive pulmonary disease (COPD) with a mean age of 68 years and a mean of forced expiratory volume in 1 sec (FEV1) of 41% predicted. In a randomized, cross-over fashion they inhaled terbutaline 1.5 mg (six puffs) followed by ipratropium 120 microg (six puffs) via MDI and nebuhaler with either two inspirations to total lung capacity and a 10-sec breath-hold per puff or with six tidal breaths per puff. Before and after BDs we measured FEV1, forced vital capacity (FVC), airways resistance using interrupter method (Rint) and 6-min walking distance (6MWD). Subsequently, we re-tested nine of these patients with the two methods of inhalation, before and after conventional doses (terbutaline 500 microg+ipratropium 40 microg), then after terbutaline 1 mg and ipratropium 80 microg and finally after nebulized terbutaline 5 mg and ipratropium 500 microg to sec whether there was a dose-dependent difference in effect between the two methods. Spirometry, slow vital capacity (SVC). inspiratory capacity and shuttle walking tests were monitored. In the original 20 patients there were highly significant improvements in all parameters after inhalers, with no significant difference between methods of inhalation. Median improvements after BDs were: FEV1 0.221 and 0.191, FVC 0.501 and 0.381 and 6MWD 40 m and 44 m, for maximal breaths and tidal breathing, respectively. For nine patients, tidal and maximal breaths produced similar effects on lung function and exercise tolerance at both doses of BDs. Nebulized BDs only improved shuttle distances slightly when compared with either method of inhalation from MDI and spacer but had no additional effect on lung function. In conclusion, in patients with moderately severe COPD, BDs given by metered dose inhaler via nebuhaler have similar effects whether given by six easy tidal breaths or the more difficult two maximal breaths with breath-hold. This holds true at small or larger doses of BD. Either method of inhaling six puffs of the BDs can be used as an effective alternative to nebulized aerosol.

Administration, Inhalation↗
PubMed1985

Changes in lung volume and deflation stability in hyaline membrane disease.

Total lung capacity (TLC), inspiratory capacity, functional residual capacity, and deflation stability of prematurely delivered Macaca nemestrina primates were measured serially during development of, and recovery from, hyaline membrane disease (HMD) to relate changes in lung volumes to changes in deflation stability. Gestational age-matched primates that did not develop HMD served as controls. TLC, measured by N2 washout, fell at 2-12 h of age (P less than 0.0001) in animals with HMD and remained lower than controls for at least 48 h (P less than 0.005). However, deflation stability, defined as the fraction of TLC remaining upon deflation to 10 cm H2O, improved from 2 to 12 h of age (P less than 0.001). Postmortem studies confirm the measurements of TLC and deflation stability and provide evidence that interstitial thickening and obstruction of air spaces with debris may be partially responsible for the observed changes in TLC in primates that develop HMD. It has been assumed that TLC is reduced in HMD because of atelectasis from elevated alveolar surface tension, but the sequential measurements in these animals suggest that other mechanisms also contribute.

Animals↗
PubMed2001

Relationship between pulmonary function and unsupported arm exercise in patients with COPD.

UNLABELLED: In patients with chronic obstructive pulmonary disease (COPD) the limitation on unsupported arm exercise (UAE) is predominantly respiratory muscle function-dependent. It is characterized by neuromechanical dysfunction (thoracoabdominal dyssynchrony) of the inspiratory muscles (diaphragm, accessory), superimposed by lung mechanics dysfunction. The undergoing mechanism is probably multifactorial. To study the relationship of resting pulmonary function and UAE performance in patients with COPD. Twenty-one patients, mean age 63 +/- 7 years, with COPD [forced expiratory volume in the first second (FEV1) 42 +/- 12% of predicted] underwent assessment of resting lung function (inspiratory capacity 57 +/- 17%; functional residual capacity 204 +/- 38% of predicted), maximal inspiratory pressure (67 +/- 14 cmH2O), upper arm circumference (30 +/- 2 cm), and symptom-limited cardiopulmonary UAE assessments. UAE consisted of bilateral anterior arm elevation to shoulder level at a rate of 40 arm strokes.minute-1. A series of stepwise multiple regression models were fitted to the data to predict exercise time from resting pulmonary function indices. RESULTS: Statistically significant correlations (r) were found between exercise time and inspiratory capacity (% of predicted) (r = 0.67, p = 0.0008), maximal inspiratory pressure (cmH2O) (r = 0.47, p = 0.03), upper arm circumference (r = 0.74, p = 0.0001), FEV1 (% of predicted) (r = 0.62, p = 0.0026), oxygen uptake (r = 0.56, p = 0.0085) and functional residual capacity (% of predicted) (r = -0.41, p = 0.06, borderline). Inspiratory capacity (% of predicted), functional residual capacity (% of predicted), upper arm circumference (cm) and FEV1 (% of predicted) explained 77% of the variance in exercise time. Therapeutic strategies that aim to increase inspiratory capacity or decrease functional residual capacity, or increase inspiratory muscle strength and upper arm/torso muscle endurance are likely to alleviate symptoms and improve UAE performance in patients with COPD.

Aged↗
PubMed1993

[Dyspnea and inspiratory effort capacity in COPD].

The aim of this work was to study the relationship between dynamic hyperinflation and dyspnoea perception on exercise in patients with chronic obstructive pulmonary disease (COPD). Seven men and three women with COPD (mean FEV1 45.9 +/- 9.8% predicted) were studied. The upper end of the visual analogue scale was anchored on a preliminary test on a cycle ergometer (day 1). On the study day (day 2) the relationship between dyspnoea and ventilatory indices during high intensity exercise was evaluated, using within-subject linear regression analysis. On a repeat study (day 3), the addition of inspiratory capacity (IC) manoeuvres allowed to monitor the end expiratory lung volume. The highest degree of within-subject correlation was observed between dyspnoea and the tidal peak inspiratory flow (PIFT), as well without (median r2 = 0.920, day 2) as with (median r2 = 0.880, day 3) IC manoeuvres. At maximal exercise, IC decreased in 8 out of 10 subjects (delta IC range -150 to -900 ml). A negative relationship was found between delta IC and the rate of increase in dyspnoea on exercise, measured as the dyspnoea/PIFT slope (r = 0.844, p < 0.01). Our results suggest that dynamic hyperinflation on exercise observed in most patients with COPD allows these subjects to minimize the rate of increase in dyspnoea on exercise.

Aged↗
PubMed1975

Evaluation of bronchial drainage in patients with cystic fibrosis.

Examined in this study are the results of six tests of pulmonary function immediately preceding and following bronchial drainage in twenty-six patients with cystic fibrosis. Highly significant increases averaging 5.67, 4.13, 13.47, and 6.98 percent occurred in peak expiratory flow rate, forced vital capacity, expiratory reserve volume, and inspiratory capacity respectively. Significant increases in peak expiratory flow rate, forced vital capacity, and inspiratory capacity were observed in a subgroup of six of the above patients who had evidence of bronchospasm. The authors conclude that bronchial drainage will produce significant increases in routine pulmonary function values. The results suggest that this treatment is most effective in clearing the larger, more proximal, airways and is of benefit even in the presence of clinical bronchospasm.

Adolescent↗
PubMed1990

Breath-stacking increases the depth and duration of chest expansion by incentive spirometry.

Although the objective of incentive spirometry is to achieve and hold high lung volumes, many patients with pain or weakness are unable to sustain the effort needed to perform effective exercises. We questioned whether using a one-way valve to prevent exhalation would allow rest between inspiratory efforts and cause volume to cumulate during successive tidal efforts, improving both the depth and duration of the inspiratory maneuver. We studied 26 cooperative but naive patients recovering from surgery, trauma, or critical illness whose pain or weakness impaired ability to achieve and sustain deep inspiration. All subjects breathed via mouthpiece from a spirometer prefilled with 100% oxygen. Three different maneuvers were performed in random order by all subjects: (1) standard inspiratory capacity without valve or inspiratory hold, (2) inspiratory capacity (IC) with breathholding aided by a one-way valve, and (3) uncoached breath-stacking, during which successive tidal breaths were cumulated by one-way valving. A fourth maneuver was added in the last 13 subjects studied: an initial coached IC effort with subsequent valved stacking of tidal efforts. When compared with IC, "breath stacking" (valved) maneuvers increased inspired volume by an average of 15 to 20% (p less than 0.05). More importantly, there was a severalfold increase in the time over which high lung volume was sustained (p less than 0.001). Our results indicate that one-way valving helps to achieve and sustain deep inspiration, even in uncoached patients.

Humans↗
PubMed1986

Respiratory effects of high thoracic epidural anaesthesia.

The respiratory effects of high thoracic epidural anaesthesia (TEA) were studied in nine healthy volunteers by means of spirometry, nitrogen single-breath test and flow-volume loop. After the baseline measurements an epidural catheter was inserted at T4 level, and 5 ml of 0.5% bupivacaine were injected. This volume led to sensory block within dermatomes T1-T5. Total lung capacity, vital capacity and inspiratory capacity decreased slightly but significantly during TEA. Expiratory reserve volume was not affected. Maximal inspiratory flow at 50% VC decreased 24%. Maximal expiratory flow at 75% VC and peak expiratory flow were not changed. N2 difference during a constant flow rate of 0.5 l/s and forced expiratory volume in 1 s were not changed, which indicates that there were no changes of bronchial tone. The respiratory effects of high TEA in this study were caused by the motor block of the intercostal muscles.

Adult↗
PubMed1992

Breathing pattern adjustments during the first year following cervical spinal cord injury.

The alterations in lung function and breathing pattern were examined in 6 quadriplegics at 3, 6 and greater than 12 months post injury, and were compared to 6 able bodied controls. Subjects were studied in both the seated and supine positions. Functional residual capacity (FRC), forced vital capacity (FVC), inspiratory capacity (IC), and maximum mouth pressure (Pimax) at FRC were measured. Total lung capacity (TLC) and residual volume (RV) were calculated. Resting breathing pattern was assessed for 20 minutes from a spirogram derived from summed rib cage and abdominal strain gauge signals. At 3 months in quadriplegics, TLC was reduced (p less than 0.05), RV increased (p less than 0.01) and FRC was normal in sitting; in supine, only TLC was reduced (p less than 0.05); Pimax was decreased (p less than 0.01) in both positions in quadriplegics at 3 months, but increased over the first year in the seated position (p less than 0.01). There were no alterations in breathing pattern at any time interval in quadriplegics in supine. In contrast, at 3 months post injury in sitting, expiratory time (Te) was shortened (p less than 0.05), tidal volume (Vt) was decreased, and heart rate elevated as compared to controls (p less than 0.05). Inspiratory time (Ti) was not significantly shortened at 3 months in quadriplegics, but a lengthening of Ti occurred between 3 and 6 months (p less than 0.025) resulting in increased Vt, and heart rate decreased to normal. Vt/Ti was reduced, and did not alter with time. The lengthening of Ti/Ttot observed in supine in control subjects (p less than 0.025), was not observed in quadriplegics. Quadriplegics sighed as frequently in supine as did controls at all stages post injury, whereas they decreased sighing frequency in sitting at 3 and 6 months post injury (p less than 0.05). The improvement in resting breathing pattern observed in quadriplegics in sitting with time, may be due to increased accessory muscle function, improved chest wall stability and thoracoabdominal coupling, or a combination of these factors. It is also possible that the alterations in breathing pattern were a response to cardiovascular adjustments occurring in the same time frame. Quadriplegics retain the sigh reflex, but do not take as many big breaths in sitting as they do in supine, probably due to the increased work of breathing in the seated posture.

Adult↗
PubMed2001

Use of forced inspiratory vital capacity to identify bronchodilator reversibility in obstructive lung disease.

The objective of this study was to assess the utility of forced inspiratory vital capacity (FIVC) to identify bronchodilator reversibility (BDR) for patients with obstructive lung disease (OLD) in relation to customary BDR criteria as defined by the American Thoracic Society (ATS). Concurrent data analysis was used in an academic medical center setting. Two hundred patients with OLD (including chronic obstructive lung disease and asthma) undergoing testing at the Pulmonary Function Laboratory at Cedars-Sinai Medical Center from January 1995 to December 1996 were identified. These 200 patients were categorized into four grades of obstruction by ATS-defined forced expiratory volume in 1 sec (FEV1) criteria (severe, moderately severe, moderate, and mild). Each of these groups was further subdivided into equal subgroups according to the presence (+) or absence (-) of BDR. Inspiratory flow-volume loops and FIVC were analyzed for each of these subgroups. Of the patients exhibiting BDR on the forced expiratory maneuver (FEM), FIVC correctly identified 53% of the cases. For patients not exhibiting BDR on FEM, FIVC identified an additional 12 cases. In 72% of cases, the maximal FIVC was not obtained from the maximal FEM flow-volume loop. FIVC inspection of the data (which were already available from standard spirometric testing) identified a subgroup of OLD patients with BDR not appreciated by FEV1 or FVC criteria, which may respond to bronchodilator therapy. The maximal FIVC value should be obtained by manual inspection to identify the best inspiratory flow-volume loop.

Adult↗
PubMed2005

Factors in maintaining long-term improvements in health-related quality of life after pulmonary rehabilitation for COPD.

The purpose of this study was to reveal predictors for the long-term effects of pulmonary rehabilitation for chronic obstructive pulmonary disease (COPD) patients, in terms of health-related quality of life (HRQoL). We investigated the long-term effects of pulmonary rehabilitation in 53 COPD patients who had completed the outpatient program and could be evaluated continuously for 1 year. We also investigated factors related to long-term maintenance of HRQoL assessed by the St George's Respiratory Questionnaire (SGRQ). In the year following the program, the only items that retained a significant improvement compared with the pre-program levels were respiratory muscle strength and 6-min walking distance. Patients whose total SGRQ score showed improvements that were maintained above the minimal clinically important difference were placed in a maintained-improvements group (n = 18, 34.0%), and the others in a non-maintained group (n = 35, 66.0%). A comparison of the groups revealed that the maintained-improvements group had significantly lower forced vital capacity (FVC), inspiratory capacity (IC), and tidal volume (TV) at rest; higher PaCO(2); greater initial impairments in HRQoL; and more frequent attendance in a maintenance program. In a multiple logistic regression model, only PaCO(2) was identified as predictor for the maintenance of improvement in HRQoL over a long term. In conclusion, higher baseline PaCO(2) is predictor of maintained, long-term improvement in HRQoL after pulmonary rehabilitation. Frequent attendance in a maintenance program is another predictor.

Aged↗