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Results for “Functional Residual Capacity”

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PubMed2006

Functional and physiologic results of video-assisted thoracoscopic diaphragm plication in adult patients with unilateral diaphragm paralysis.

BACKGROUND: Plication of the hemidiaphragm for unilateral diaphragm paralysis is infrequently performed in adults. Barriers to diaphragm plication have included the perceived need for thoracotomy and uncertainty of the potential benefits. The purpose of this investigation was to assess the effects of video-assisted thoracoscopic diaphragm plication in symptomatic adult patients with unilateral diaphragm paralysis. METHODS: Patients with unilateral diaphragm paralysis underwent an evaluation that included a chest radiograph, fluoroscopic sniff test, pulmonary spirometry, and the Medical Research Council (MRC) dyspnea score. Patients with symptomatic unilateral diaphragm paralysis present for at least 6 months were offered video-assisted thoracoscopic diaphragm plication. Patients who underwent diaphragm plication as well as those who declined surgery were reassessed at 6 months with a chest radiograph, spirometry, and the MRC dyspnea score. RESULTS: Twenty-five patients underwent left (19) or right (6) diaphragm plication through video-assisted thoracoscopic diaphragm plication (22) or thoracotomy (3). There were no operative deaths. Mean hospital length of stay for diaphragm plication was 3.7 days for video-assisted thoracoscopic diaphragm plication and 5.4 days for thoracotomy. After diaphragm plication, mean forced vital capacity, forced expiratory volume at 1 second, functional residual capacity, and total lung capacity improved by 17%, 21.4%, 20.3%, and 16.1%, respectively (p < 005) at 6 months. Mean MRC dyspnea scores also significantly improved in the operative cohort (p < 0001). Seventeen patients in the surgical cohort had returned to work at 6 months. Seven patients treated without surgery displayed a trend toward more frequent hospitalizations and deteriorating pulmonary spirometry and MRC dyspnea scores during the follow-up period. CONCLUSIONS: Plication of the hemidiaphragm using minimally invasive techniques produced significant improvements in patients' functional status, pulmonary spirometry, and MRC dyspnea scores. Video-assisted thoracoscopic diaphragm plication should be considered appropriate therapy in symptomatic adult patients with unilateral diaphragm paralysis.

Adult↗

PubMed2006

Lung function in infants after repair of congenital diaphragmatic hernia.

BACKGROUND/PURPOSE: Congenital diaphragmatic hernia (CDH) is initially characterized by severe restrictive lung defect and low lung compliance, but survivors have relatively few abnormalities later in life. We studied the changes in lung growth and function in infants after the repair of CDH. METHODS: Retrospective analysis of pulmonary function tests was performed during the first 24 months of life in 56 infants (33 male and 23 female) after repair of CDH. Lung function (functional residual capacity [FRC], respiratory system compliance [C(rs)] and resistance [R(rs)], and maximum expiratory flow rate at FRC [V'(maxFRC)]) were compared among 4 different ages (0-3, 4-6, 7-12, and 13-24 months). RESULTS: All indices of lung function (mean +/- SD of z scores) were abnormal during the first 6 months of life but were almost normalized by 24 months (P < .0001): FRC, from -0.84 +/- 0.5 to 3.26 +/- 2.07; C(rs), from -0.87 +/- 0.4 to 1.84 +/- 1.75; R(rs), from 2.85 +/- 2.71 to -0.23 +/- 2.03, and V'(maxFRC), from -1.63 +/- 0.4 to -0.09 +/- 0.94. There was significant correlation (P < .001) between lung function and increase in age, height, and especially weight. CONCLUSIONS: Lung growth and function gradually normalize between 6 and 24 months of life after repair of CDH.

Airway Resistance↗

PubMed1998

Postural changes in respiratory function.

Changes in body position alters the functional residual capacity (FRC). Most anesthetics reduce FRC in the recumbent but not sitting position. Inspired gas distribution in anesthesia-paralyzed subjects whose lungs are mechanically ventilated, is different from that in the awake state in all but the prone position. The function of the diaphragm is altered by postural changes. The pattern of motion of the diaphragm is different during mechanical ventilation than during spontaneous breathing. Also the end-expiratory shape is affected by induction of anesthesia, but this shape change contributes little to the reduction of FRC. The distribution of pulmonary blood flow is determined not only by gravity, but also by an intrinsic non-gravity dependent factor. These two factors can be additive in some positions but opposing in others.

Anesthetics, General↗

PubMed1997

Effect of volume recruitment on response to surfactant treatment in rabbits with lung injury.

We determined if surfactant treatment effect can be enhanced by mechanical volume recruitment during surfactant administration by measuring functional residual capacity, tidal volume, the alveolar portion of tidal volume, dynamic compliance of the respiratory system, a/A ratio, and PaCO2 by measuring before and after surfactant administration to rabbits with lung injury induced by airway lavage. There was improvement in all lung function indices when surfactant was given with volume recruitment, but when surfactant was given without volume recruitment, the only index to show significant improvement was a/A ratio of oxygenation. These results support the hypothesis that mechanical recruitment of terminal airspaces from a previously unventilated compartment will enhance the effectiveness of surfactant replacement by facilitating the distribution of instilled surfactant to this compartment.

Animals↗

PubMed1985

Moment analysis of multibreath nitrogen washout in young children.

The purpose of this study was to determine whether on-line computerized moment analysis of multibreath N2 washout (MBNW) could be used as a method of estimating lung function in children too young to cooperate with routine pulmonary function testing. The limits of normal variability were determined from results obtained from duplicate studies performed on 36 healthy children ages 3-6 yr. Five healthy adults were studied for comparison. Test sensitivity was estimated by comparing the results in the healthy group to those of 10 age-matched children with cystic fibrosis (CF). Outcome variables of interest included functional residual capacity, the first-to-zeroth moment ratio (M1/M0), the second-to-zeroth moment ratio (M2/M0), and the lung clearance index. Test precision in the healthy group was high with the intrasubject coefficient of variation for all variables being less than 10%. There was no difference in mean within- or among-subject variability between the healthy children and the older, theoretically more cooperative, healthy adults. Mean M1/M0 and M2/M0 were both higher in CF than in the healthy group, 2.69 vs. 2.32 and 13.04 vs. 9.31, respectively (P less than 0.001). Moment ratios in CF showed good negative correlations with Shwachman scores; thus those CF patients with the most advanced lung disease had the highest moment ratios and vice versa. Moment analysis of MBNW has promise as a means of quantifying lung function in young children, since the method is noninvasive, low in inherent variability, requires only quiet breathing, and has the sensitivity required to detect rather mild ventilation inhomogeneity.

Child↗

PubMed1999

Neonatal lung function in very immature infants with and without RDS.

Some infants, despite being born at low gestations (< 28 weeks gestational age) do not develop RDS and are not surfactant treated. The changes in lung function during the neonatal period in such infants have not been explored, hence it is unknown whether they are similar to those of surfactant treated infants with RDS of similar gestational age. Such data would facilitate assessment of the impact of surfactant administration on the lung function abnormalities of very immature infants with RDS. We, therefore, compared the results of neonatal lung function measurements from immature infants with RDS who received surfactant to those from infants with non-RDS respiratory distress not so treated and matched to the RDS infants for gestational age and within 10% of birthweight. Compliance and functional residual capacity (FRC) were measured daily for the first five days and then at 1, 2 and 4 weeks in 16 infants, median gestational age 27 weeks (range 25-27 weeks). Although exogenous surfactant administration to the immature infants with RDS was associated with improvements in lung function, the non RDS, non surfactant treated infants had both higher compliance (p < 0.05) and lung volumes (p < 0.01) throughout the perinatal period. These results demonstrate surfactant administration does not fully correct the perinatal lung function abnormalities of very immature infants with RDS.

Birth Weight↗

PubMed2004

Use of submaximal inhalation and spirometry to assess the effects of ozone exposure.

Spirometric measures of airway obstruction are strongly influenced by the neurally mediated reduction in total lung capacity that accompanies ozone exposure. This study was conducted to evaluate a method for quantifying the effects of performing spirometry from a reduced inspiratory position on measures of airway obstruction, and to apply the method to published ozone-response data. Nineteen healthy, nonsmoking adults, 18-30 yr of age, each performed 17 forced expiratory maneuvers from inspiratory volumes that ranged from functional residual capacity to total lung capacity. In general, measures of airway obstruction were related strongly to total expired volume, and approximately 80% of the ozone-induced decrease in forced expiratory volume in 1 s (FEV1.0) resulted from the reduction in forced vital capacity. Results indicated that, for young, healthy, nonsmoking adults, spirometric values from maneuvers conducted from reduced inspiratory positions can be predicted accurately and precisely in the unexposed state, allowing interpretation of measures of ozone-induced airway obstruction.

Adolescent↗

PubMed1992

Effects of analysis method and forcing waveform on measurement of respiratory mechanics.

The respiratory system has been shown to exhibit nonlinear mechanical properties in the frequency (f) range of normal breathing, manifested by tidal volume (Vt) dependence. Calculations of respiratory system resistance (R) and elastance (E) from pressure-flow measurements during external forcing at a given f may be ambiguous, especially if non-sinusoidal forcing waveforms are used. We evaluated the degree to which R and E depended upon: (1) analysis method (Fourier transform, multiple regression and pressure-volume loop analysis) and; (2) shape of the forcing waveform (sinusoidal, quasi-sinusoidal and step). We measured pressure and flow at the mouth of 5 healthy, awake subjects, relaxed at functional residual capacity, during forcing with the three different waveforms in the normal range of f (0.2-0.6 Hz) and Vt (250-750 ml). During sinusoidal forcing, E and R were not affected by analysis method (P greater than 0.2). With Fourier transform and multiple regression, E was not affected by waveform shape (P greater than 0.05); with loop analysis, E was slightly (less than 10%) higher during quasi-sinusoidal and step forcing than during the sine (P less than 0.05). R was least affected by waveform shape with Fourier transform. We conclude that, in the f and Vt range of normal breathing: (1) respiratory system impedance is 'quasi-linear,' i.e. despite dependencies of R and E on Vt, non-linearities are not large enough to restrict interpretation of R and E at a given f and Vt; (2) it may be possible to measure R and E using non-sinusoidal forcing waveforms available on most clinical ventilators, incurring only modest error.

Adult↗

PubMed2000

Flow limitation and dynamic hyperinflation during exercise in COPD patients after single lung transplantation.

STUDY OBJECTIVE: Using the negative expiratory pressure (NEP) method, we have previously shown that patients receiving single lung transplantation (SLT) for COPD do not exhibit expiratory flow limitation and have little dyspnea at rest. In the present study, we assessed whether SLT patients exhibit flow limitation, overall hyperinflation, and dyspnea during exercise. METHODS: Expiratory flow limitation assessed by the NEP method and inspiratory capacity maneuvers used to determine end-expiratory lung volume (EELV) and end-inspiratory lung volume (EILV) were performed at rest and during symptom-limited incremental cycle exercise in eight SLT patients. RESULTS: At the time of the study, the mean (+/- SD) FEV(1), FVC, functional residual capacity, and total lung capacity (TLC) amounted to 55 +/- 14%, 67 +/- 12%, 137 +/- 16%, and 110 +/- 11% of predicted, respectively. At rest, all patients did not experience expiratory flow limitation and were without dyspnea. At peak exercise, the maximal mechanical power output and maximal oxygen consumption amounted to 72 +/- 20% and 65 +/- 8% of predicted, respectively, with a maximal dyspnea Borg score of 6 +/- 3. All but one patient exhibited flow limitation and dynamic hyperinflation; the EELV and EILV amounted to 74 +/- 5% and 95 +/- 9% TLC, respectively. The patient who did not exhibit flow limitation during exercise had the lowest dyspnea score. CONCLUSION: Most SLT patients for COPD exhibit expiratory flow limitation and dynamic hyperinflation during exercise, whereas maximal dyspnea is variable.

Aged↗

PubMed1980

Effect of regional chest wall restriction on regional lung function.

The effect of impeding regional chest wall excursion on regional lung function was assessed. Fourteen subjects were studied while seated in a volume-displacement plethysmography. The lower rib cage and epigastrium were restricted with an inextensible binder. Because such restriction increases lung recoil and diminishes functional residual capacity (FRC), all measurements were made at the unstrapped FRC (FRCus). Regional excursion of the chest wall was measured with magnetometers placed anteroposteriorly at the sternomanubrial angle, the xyphoid, and umbilicus and transversely at the level of the xyphoid at the midaxillary line. Regional lung function was assessed by measuring the distribution of inspired boluses and washout of 133Xe with scintillation detectors positioned against the subject's back at the apical, middle, and basal regions. Restriction of the lower chest wall impeded expansion of the lower rib cage and diminished the distribution of inspired gas to and washout of the lung bases. The upper rib cage expanded normally and was associated with an increased distribution of inspired gas and normal distribution of washout to the apices. These results suggest that regional lung function was dependent on regional rib cage excursion.

Adult↗

PubMed1983

A comparison of the pulmonary effects of 0.5 ppm versus 1.0 ppm sulfur dioxide plus sodium chloride droplets in asthmatic adolescents.

The effects of inhaled sulfur dioxide (SO2) on pulmonary function in nine adolescent subjects with extrinsic asthma were studied. The exposure modes, inhaled via a mouthpiece, were (1) 1 mg/m3 sodium chloride solution droplet aerosol (NaCl); (2) 0.5 ppm SO2 + NaCl; or (3) 1.0 ppm SO2 + NaCl. All exposures were at greater than or equal to 75% relative humidity and approximately 22 degrees C. The following pulmonary functional measurements, with the subject seated in a body plethysmograph, were recorded: total respiratory resistance (RT), functional residual capacity (FRC), maximal flow at 50% and 75% expired vital capacity (Vmax50 and Vmax75), and forced expiratory volume in one second (FEV1). Following 10 min of exposure to either SO2 mode during moderate exercise on a treadmill, statistically significant changes in all pulmonary functional measurements except FRC were seen. There were no statistically significant changes following 10 min of exposure during moderate exercise to the NaCl droplet aerosol alone. Since the average pulmonary changes following exposure to 0.5 ppm SO2 mixture during moderate exercise ranged from 8 to 47%, we conclude that this dose of SO2 is above the response threshold for these subjects. To explore the effects of nasal (or oronasal) inhalation on the SO2-induced pulmonary functional changes, 7 of the 9 subjects inhaled 0.5 ppm SO2 + NaCl via a face mask with no nose clips. The average percentage changes in pulmonary functional values seen after exposure via face mask were similar to those seen after exposure via mouthpiece. However, the changes seen after exposure via face mask were not as consistent as following inhalation via mouthpiece and not statistically different from baseline. We conclude that oral, and to a lesser degree oronasal, inhalation of 0.5 ppm of SO2 elicits SO2-induced changes in pulmonary function in these subjects.

Adolescent↗

PubMed2001

Measurements of hyperpolarized gas properties in the lung. Part III: (3)He T(1).

Hyperpolarized (3)He spin-lattice relaxation was investigated in the guinea pig lung using spectroscopy and imaging techniques with a repetitive RF pulse series. T(1) was dominated by interactions with oxygen and was used to measure the alveolar O(2) partial pressure. In animals ventilated with a mixture of 79% (3)He and 21% O(2), T(1) dropped from 19.6 sec in vivo to 14.6 sec after cardiac arrest, reflecting the termination of the intrapulmonary gas exchange. The initial difference in oxygen concentration between inspired and alveolar air, and the temporal decay during apnea were related to functional parameters. Estimates of oxygen uptake were 29 +/- 11 mL min(-1) kg(-1) under normoxic conditions, and 9.0 +/- 2.0 mL min(-1) kg(-1) under hypoxic conditions. Cardiac output was estimated to be 400 +/- 160 mL min(-1) kg(-1). The functional residual capacity derived from spirometric magnetic resonance experiments varied with body mass between 5.4 +/- 0.3 mL and 10.7 +/- 1.1 mL. Magn Reson Med 45:421-430, 2001.

Animals↗

PubMed1996

Comparison of heliox and oxygen as washing gases for the nitrogen washout technique in preterm infants.

The nitrogen washout technique usually involves exposure of the patient to 100% oxygen for several minutes. This may be dangerous in preterm infants who are at risk of retinopathy of prematurity (ROP). We wanted to know whether heliox (79% He, 21% O2) can be used instead of oxygen when determining functional residual capacity (FRC). FRC measurements were made in 14 preterm infants [median (range) gestational age at birth 34 wk (27-37 wk), and at time of study 36 wk (33-40 wk)] who were breathing room air. FRC was measured using a computerized infant pulmonary function system, beginning in random order with either 100% O2 followed by heliox or vice versa. There was no systematic difference between the two methods with regard to lung volume measurements: mean (SD) FRC values, corrected for body weight, were 22.9 (7.1) mL/kg for O2 and 23.4 (7.0) mL/kg for heliox. We did not observe a systematic influence of the type of washing gas used (heliox or oxygen) on FRC in these infants. Our results suggest that the use of heliox instead of pure oxygen may be a suitable and safer alternative for FRC measurements with the nitrogen washout technique in preterm infants who are breathing low concentrations of inspired oxygen and are still at risk of ROP.

Functional Residual Capacity↗

PubMedDate not supplied

Lung transfer factor for CO at rest in normal children by a steady-state method.

Lung transfer for CO (TLCO) was measured at rest in 94 normal children (47 boys and 47 girls) whose ages ranged from 3.5 to 16 years. A steady-state method, using a technique of alveolar sampling based on the equality of the mean expiratory and alveolar respiratory quotients, was employed. Highly significant correlations, statistically different for boys and girls, were fond between TLCO and standing height. TLCO was also linearly correlated with the functional residual capacity--the only pulmonary volume measurable in very young children--but without any sex difference. A multiple linear regression relates TLCO to FRC and height. Variance analysis shows the preponderant influence of FRC.

Adolescent↗

PubMed2002

Mode shift of an inhaled aerosol bolus is correlated with flow sequencing in the human lung.

We studied the effects on aerosol bolus inhalations of small changes in convective inhomogeneity induced by posture change from upright to supine in nine normal subjects. Vital capacity single-breath nitrogen washout tests were used to determine ventilatory inhomogeneity change between postures. Relative to upright, supine phase III slope was increased 33 +/- 11% (mean +/- SE, P < 0.05) and phase IV height increased 25 +/- 11% (P < 0.05), consistent with an increase in convective inhomogeneity likely due to increases in flow sequencing. Subjects also performed 0.5-microm-particle bolus inhalations to penetration volumes (V(p)) between 150 and 1,200 ml during a standardized inhalation from residual volume to 1 liter above upright functional residual capacity. Mode shift (MS) in supine posture was more mouthward than upright at all V(p), changing by 11.6 ml at V(p) = 150 ml (P < 0.05) and 38.4 ml at V(p) = 1,200 ml (P < 0.05). MS and phase III slope changes correlated positively at deeper V(p). Deposition did not change at any V(p), suggesting that deposition did not cause the MS change. We propose that the MS change results from increased sequencing in supine vs. upright posture.

Adult↗

PubMed2005

Exaled nitric oxide and air trapping correlation in asthmatic children.

Exhaled nitric oxide (eNO) levels have been shown to correlate with atopy and with airway hyperresponsiveness but not with standard spirometry. The aim of our study was to evaluate the correlation between eNo levels and functional residual capacity (FRC), residual volume (RV), RV to total lung capacity (TLC) ratio, and pulmonary resistances in asthmatic children ages 6-13 years. Forty-nine patients (35 males) were enrolled in the study. Nineteen of them were not receiving inhaled corticosteroids. The eNO levels were measured by chemiluminescence's analyzer and lung function study were performed by body box plethysmography. As expected, there was no correlation between eNO levels and forced vital capacity (FVC); forced expiratory volume in the first second (FEV1); mid respiratory flow between 25 and 75% of the vital capacity (MEF(25 -75)), FEV1/FVC, and pulmonary resistances. Instead a correlation was found between eNO level and RV both considering all the study population together (r = 0.51, P = 0.001) and separately the asthmatic children not receiving ICS (r = 0.6, P = 0.003). In the patients receiving ICS the correlation was still present (r = 0.43, P = 0.01). The correlation between eNo levels and RV may reflect the effect of airway inflammation on NO production and diffusion as well as peripheral airway trapping and consequent RV.

Administration, Inhalation↗

PubMed1978

Respiratory mechanics in the anesthetized rat.

Functional residual capacity (FRC) and pressure-volume (PV) curves of the lung, chest wall, and total respiratory system were studied in 15 anesthetized rats, weighing 307 +/- 10 (SE) g. Pleural pressure was estimated from the esophageal pressure measured with a water-filled catheter. The FRC determined by body plethysmograph was slightly and significantly larger than FRC determined from saline displacement of excised lungs. The difference may be accounted for by O2 uptake by lung tissue, escape of CO2 through the pleura, and abdominal gas. Paralysis in the prone position did not affect FRC, and abdominal gas content contributed only slightly to the FRC measured by body plethysmograph. Values of various pulmonary parameters (mean +/- SE) were as follows: residual volume, 1.26 +/- 0.13 ml; FRC, 2.51 +/- 0.20 ml; total lung capacity, 12.23 +/- 0.55 ml; compliance of the lung, 0.90 +/- 0.06 ml/cmH2O; chest wall compliance, 1.50 +/- 0.11 ml/cmH2O; and respiratory system compliance, 0.57 +/- 0.03 ml/cmH2O. The lung PV curve did not show a consistent change after the chest was opened.

Anesthesia↗

PubMed2004

Hyperpolarized 3He MRI and 81mKr SPECT in chronic obstructive pulmonary disease.

PURPOSE: During recent years, magnetic resonance imaging (MRI) using hyperpolarised (HP) 3He gas has emerged as a promising new method for the imaging of lung ventilation. However, systematic comparisons with nuclear medicine techniques have not yet been performed. The aim of this study was to compare ventilation imaging methods in 26 patients with chronic obstructive pulmonary disease (COPD) and nine lung healthy volunteers. METHODS: HP 3He MRI, 81mKr single-photon emission computed tomography (SPECT), high-resolution computed tomography (HRCT) and pulmonary function tests were performed. The three scans were scored visually as percentage of non-ventilated/diseased lung, and a computer-based objective measure of the ventilated volume in HP 3He MRI and 81mKr SPECT and an emphysema index in HRCT were calculated. RESULTS: We found a good correlation between HP 3He MRI and 81mKr SPECT for both visual defect score (r=0.80, p<0.0001) and objective estimate of ventilation (r=0.45, p=0.0157). In addition, both scans were well correlated with reference methods for the diagnosis of emphysema (pulmonary function test and HRCT). The defect scores were largest on 81mKr SPECT (the score on HP 3He MRI was one-third less than that on 81mKr SPECT), but the difference was reduced after normalisation for different breathing depths (HP 3He MRI at total lung capacity; 81mKr SPECT at tidal breathing at functional residual capacity). CONCLUSION: HP 3He MRI provides detailed ventilation distribution images and defect scores are comparable on HP 3He MRI and 81mKr SPECT. Additionally, new insights into the regional pulmonary microstructure via the apparent diffusion coefficient measurements are provided by HP 3He MRI. HP 3He MRI is a promising new diagnostic tool for the assessment of ventilation distribution.

Administration, Inhalation↗