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At least 19 recordsLinked to original sources
PubMed1993

Effects on lung compliance, lung volume, and single-breath transfer factor for carbon monoxide in sheep with lentivirus-induced lymphoid interstitial pneumonia.

Static lung compliance, static lung volumes, and transfer factor for carbon monoxide were measured in 12 anesthetized adult Texel ewes seropositive for maedi-visna virus (MVV) and in 11 breed-, sex-, and age-matched seronegative controls. Median static lung compliance in MVV-infected sheep (1.24 L.kPa-1; range, 0.27 to 2.20 L.kPa-1) was not significantly different from that in controls (1.58 L.kPa-1; range, 0.82 to 2.08 L.kPa-1). Median body weight of MVV-infected sheep (56 kg; range, 40 to 75 kg) was significantly (P < 0.05) less than that of controls (65 kg; range, 53 to 87 kg). Median effective alveolar lung volume in MVV-infected sheep (3.36 L; range, 1.44 to 4.52 L) was significantly (P < 0.01) less than that in controls (4.12 L; range, 3.75 to 4.90 L). Median effective end expiratory lung volume in MVV-infected sheep (1.20 L; range, 0.56 to 1.99 L) was significantly (P < 0.001) less than that of controls (1.98 L; range: 1.76 to 2.78 L). Median lung volumes expressed per unit of body weight did not differ significantly between the groups. Median single-breath transfer factor for carbon monoxide in MVV-infected sheep (7.89 mmol.min-1.kPa-1; range, 3.45 to 12.74 mmol.min-1.kPa-1) was significantly (P < 0.001) less than that in controls (14.10 mmol.min-1.kPa-1; range, 10.02 to 18.30 mmol.min-1.kPa-1).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1980

A comparison of the effects of paraquat and diquat on lung compliance, lung volumes and single breath diffusing capacity in the rat.

Paraquat intoxication in its initial stage is characterized histologically in the lungs by atelectasis, hyaline membrane formation, alveolar edema and vascular hemorrhage often into the interstitium or air spaces. Information on the functional modification of paraquat-damaged lungs has been lacking. We evaluated lung volumes, single breath diffusing capacity of the lungs for carbon monoxide (DLCO) and static lung compliance (Cst(L)) in rats treated with paraquat or diquat. Measurements were made 12, 24, 48, and 72 h after treatment. Paraquat by intratracheal (i.t.) instillation 0.5 mg/kg or by intraperitoneal injection (i.p.) 27 mg/kg significantly decreased (P less than 0.01) the body weight, total lung capacity (TLC), functional residual capacity (FRC), vital capacity (VC), residual volume (RV), DLCO, apparent alveolar volume (VA) and Cst(L). At a lower dose level (13.5 mg/kg), the effects of paraquat peaked at about 24 h following treatment, causing a significantly decreased (P less than 0.01) VC and TLC. Diquat i.t. or i.p. had little effect on the lungs. However, diquat i.p. decreased body weight (P less than 0.01) and caused a slight increase (P less than 0.05) in VC. The data obtained are consistent with the known pathological changes seen in paraquat-damaged lungs in that, by both routes, paraquat caused severe lung damage associated with decreased elasticity of the lungs and thorax, destruction of gas exchanging alveolar surfaces, and edema. These changes were detected reliably by lung function measurements.

Animals↗
PubMed1993

Lung compliance, lung volume and transfer factor for carbon monoxide in anaesthetised sheep: normal values and reproducibility of measurements.

Measurements of quasistatic compliance (Cqst), effective alveolar volume (VA,eff) and single-breath transfer factor for carbon monoxide (TL,CO, 'sb') were completed in 16 normal, anaesthetised, adult Texel ewes. Regression equations were computed for these variables as a function of bodyweight and the optimal equations selected. The 95 per cent prediction intervals for the equations were calculated such that normal lung function in similar sheep could be accurately predicted. The long term reproducibility of these measurements was assessed in nine sheep, measured at monthly intervals over a period of five months. Although measurements made in individual sheep were often highly variable, the variation between repeated measurements on the separate days for the group was insignificant.

Anesthesia, General↗
PubMed1992

Effect of bronchial smooth muscle contraction on lung compliance.

Lung compliance is generally considered to represent a blend of surface and tissue forces, and changes in compliance in vivo are commonly used to indicate changes in surface forces. There are, however, theoretical arguments that would allow contraction of airway smooth muscle to affect substantially the elasticity of the lung. In the present study we evaluated the role of conducting airway contraction on lung compliance in vivo by infusing methacholine (MCh) at a constant rate into the bronchial circulation. With a steady-state MCh infusion of 2.4 micrograms/min into the bronchial perfusate (perfusate concentration = 0.7 microM), there was an approximate doubling of lung resistance and a 50% fall in dynamic compliance. There were also significant decreases in chord compliance measured from the quasi-static pressure-volume curves and in total lung capacity and residual volume. When the same infusion rate was administered into the pulmonary artery, no changes in lung mechanics were observed. These results indicate that the conducting airways may have a major role in regulating lung elasticity. This linkage between airway contraction and lung compliance may account for the common observation that pharmacological challenges given to the lung usually result in similar changes in lung compliance and airway conductance. Our results also suggest the possibility that the lung tissue resistance, which dominates the measurement of lung resistance in many species, might in fact reflect the physical properties of conducting airways.

Airway Resistance↗
PubMed1979

Lung compliance and lung morphology following artificial ventilation in the premature and full-term rabbit neonate.

Rabbit neonates delivered on day 27--30 of gestation were subjected to intermittent positive pressure ventilation (IPPV) for 60 min. Tidal volume was standardized to 10 ml/kg, and the insufflation pressure required to maintain this tidal volume was recorded. The quasistatic compliance of the lung-thorax system, corrected for variations in body weight, was significantly lower in animals delivered on day 27--28 than in those delivered on day 29--30. Immature animals with low lung-thorax compliance (less than 0.40 ml/cm H2O.kg) regularly developed widespread necrosis of bronchiolar epithelium following IPPV, whereas no such lesions were observed in mature animals. It seems probable that these lesions are secondary to overdistension of bronchioles during IPPV and that this abnormal expansion pattern is related to a deficiency of surfactant in the lungs of immature newborn animals.

Animals↗
PubMed1978

Indirect assessment of lung compliance in chronic lung diseases.

The slope of the flow volume curves was analysed in 20 normal subjects 28 patients with irreversible chronic airway obstruction, 24 patients with bronchial asthma, 8 patients with diffuse interstitial fibrosis and 7 patients with extensive bronchiectasis. Time constant of the system was taken as the slope of the curve between 50 and 25% of the vital capacity. When considered along with plethysmographically obtained airway resistance, an indirect estimate of the lung compliance was obtained. Significant differences in the estimated lung compliance in the normal subjects, patients with obstructive lung disease or diffuse interstitial fibrosis were demonstrated.

Airway Resistance↗
PubMed1996

Restoration of lung compliance with calf lung surfactant extract and a surfactant analog in an in situ model of surfactant deficiency in rats.

We have developed a standardized in situ lung surfactant deficiency model in the rat by using a single bronchoalveolar lavage (BAL). The purpose of this study was to assess the usefulness of surfactants and surfactant analogs in terms of their in vivo physiological properties. Calf lung surfactant extract (CLSE) was shown to improve lung compliance in a dose-dependent manner in this surfactant deficiency model when administered intratracheally immediately after BAL. In addition, CLSE formulated with a diether (palmityl) phosphonolipid surfactant analog significantly improved the compliance post-BAL as compared to CLSE alone. We propose that this in situ bioassay may be useful for the assessment of physiological capabilities of surfactants, surfactant analogs and surfactant formulations.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2000

Variations in end-expiratory pressure during partial liquid ventilation: impact on gas exchange, lung compliance, and end-expiratory lung volume.

STUDY OBJECTIVES: To determine the effects of different levels of positive end-expiratory pressure (PEEP) during partial liquid ventilation (PLV) on gas exchange, lung compliance, and end-expiratory lung volume (EELV). DESIGN: Prospective animal study. SETTING: Animal physiology research laboratory. SUBJECTS: Nine piglets. INTERVENTIONS: Animals underwent saline solution lavage to produce lung injury. Perflubron was instilled via the endotracheal tube in a volume estimated to represent functional residual capacity. The initial PEEP setting was 4 cm H(2)O, and stepwise changes in PEEP were made. At 30-min intervals, the PEEP was increased to 8, then 12, then decreased back down to 8, then 4 cm H(2)O. MEASUREMENTS AND RESULTS: After 30 min at each level of PEEP, arterial blood gases, aortic and central venous pressures, heart rates, dynamic lung compliance, and changes in EELV were recorded. Paired t tests with Bonferroni correction were used to evaluate the data. There were no differences in heart rate or mean BP at the different PEEP levels. CO(2) elimination and oxygenation improved directly with the PEEP level and mean airway pressure (Paw). Compliance did not change with increasing PEEP, but did increase when PEEP was lowered. EELV changes correlated directly with the level of PEEP. CONCLUSIONS: As previously reported during gas ventilation, oxygenation and CO(2) elimination vary directly with PEEP and proximal Paw during PLV. EELV also varies directly with PEEP. Dynamic lung compliance, however, improved only when PEEP was lowered, suggesting an alteration in the distribution of perflubron due to changes in pressure-volume relationships.

Animals↗
PubMed1975

Local control of pulmonary resistance and lung compliance in the canine lung.

Local control of pulmonary resistance and lung compliance was studied in the in situ left lower lobe of the canine lung. Recirculation of blood through the lobe while the Pco2 of the ventilatory gas was varied resulted in an increase in resistance and a decrease in compliance only when the pulmonary venous pH was greater than 7.42. Alternating sodium bicarbonate and lactic acid infusion while alveolar Pco2 was maintained below 5 mmHg demonstrated the dependence of the hypocapnic response on the acid-base status of the blood perfusing the respiratory airways. The increase in resistance and decrease in compliance observed at a pulmonary venous pH of 7.64 was comparable to that observed after lobar pulmonary artery occlusion. Varying degrees of hypoxia did not significantly affect bronchomotor tone, nor was the bronchoconstriction following lobar pulmonary artery occlusion affected by the hypoxia. Vagal stimulation superimposed on a stepwise increase in pulmonary venous pH from 7.32 to 7.62 resulted in an increase in resistance which paralleled the increase in resistance when pulmonary venous pH alone was increased. Compliance was not significantly affected by vagal stimulation at any level of pulmonary venous pH.

Airway Resistance↗
PubMed1987

Lung compliance as a measure of lung function in newborns with respiratory failure requiring extracorporeal membrane oxygenation.

Extracorporeal membrane oxygenation (ECMO) can now be used as an alternative mode of therapy for infants 2.0 kg or more with life-threatening respiratory failure. Current criteria for removal from ECMO are limited. We attempted to determine whether lung compliance (CL) could be used as a sensitive indicator of the neonates' lung improvement while they are on ECMO, as well as a predictor of their ability to tolerate removal from bypass. We obtained serial CL measurements in 13 infants, all of whom weaned successfully from ECMO. All had an initial CL on ECMO of 0.5 ml/cm H2O X kg or less (mean = 0.3), with a final CL of 0.8 ml/cm H2O X kg or more (mean = 1.7). The average change in CL from the initial to the final measurement was 0.6 ml/cm H2O X kg or more (mean = 1.5). CL findings correlated well with estimated bypass, expressed as a percent of cardiac output, and a radiographic score of pulmonary abnormality (r = -.66, p less than .0001, and r = -.52, p less than .0001, respectively). We conclude that CL measurements can be used to monitor clinical improvement in infants on ECMO, to predict their successful removal from bypass, and ultimately to shorten their total time spent on bypass.

Cardiac Output↗
PubMed1977

Hydrostatic pulmonary edema in the cat. Effects on pulmonary blood and water volumes and on lung compliance.

The effect on lung compliance of changes in intra- and extravascular volumes has been studied. Such changes were induced by inflation and deflation of a balloon placed in the left atrium in open-chest cats. Blood constituents were labeled with isotopes, and tissue water content was found from the wet/dry labeled with isotopes, and tissue water content was found from the wet/dry weight ratio. When left atrial pressure (PLA) was elevated to a value not exceeding 32 mmHg (4.256 kPa), there was only a minute increase in tissue water volume, and we observed a reversible reduction in lung compliance related to the rise in lung blood volume. At higher PLA, a rapid rise occurred in extravascular fluid volume, with evidence of alveolar flooding. Earlier experiemtns have shown that, in isolated perfused lung, a situation of slow, steady increase in interstitial fluid can be created. This does not seem to be the case with lungs in situ: once the lymphatic drainage is unable to cope with transvascular fluid flow, an unstable situation is created. This rapidly leads to alveolar flooding and a fall in compliance in addition to that caused by a rise in blood volume. From our fluid and pressure determinations, we calculated a filtration coefficient (Kf) of 0.45 ml/100 g wet lung X cmH2O X h. This is within the range reported for sheep lungs. Observation of dynamic lung compliance cannot be used for detection of interstitial fluid accumulation. It appears, however, that in contrast to isolated lungs, this phase of edema-formation rapidly leads to alveolar flooding.

Animals↗
PubMed1995

Lung compliance following cardiac arrest.

OBJECTIVE: To determine lung compliance in patients who had out-of-hospital cardiac arrests. METHODS: A prospective, observational study of patients suffering nontraumatic cardiopulmonary arrest and requiring CPR at one university hospital ED. Following termination of resuscitation efforts, lung compliance was measured. Measurements were made while inflating the lung from 250 mL to 2,000 mL (in 250-mL increments) using a calibrated supersyringe. Airway flow and pressure were measured at the endotracheal tube with a pneumotachograph and a pressure transducer. Flow and pressure signals were recorded by a respiratory monitor and used to construct pressure-volume curves for calculation of lung compliance. RESULTS: The 25 cardiac arrest patients (17 men, eight women) had a mean (+/- SD) age of 65 +/- 7 years. Mean lung compliance was 0.051 +/- 0.011 L/cm H2O. Lung compliance was smaller at low lung volumes, suggesting the presence of alveolar collapse. Compliance values from 500 mL to 1,500 mL were similar. Compliance also diminished with increasing duration of CPR. CONCLUSIONS: One previous publication suggested that lung compliance following resuscitation is 0.022 L/cm H2O. The results of this study, using the accepted standard measurements of static lung compliance, suggest that true compliance is twice this value. This finding has important ramifications for future research on ventilation during resuscitation and current ventilation standards.

Adult↗
PubMed2001

Increased lung compliance in response to a moderate hyperoxic exposure.

With deep saturation diving a reduction in vital capacity caused by oxygen toxicity may be opposed by a training effect of respiratory muscles due to increased gas density and work of breathing. We measured lung and chest wall mechanics before and after a 28-day saturation dive to a pressure of 0.25 MPa with the same profile of oxygen exposure as in a deep dive to a pressure of 3.7 MPa; 40 kPa during the isopression phase and 50 kPa during the decompression phase. Eight males aged 22-28 yr served as subjects. The measurements included dynamic lung volumes, static lung compliance, lung recoil pressure, and maximal respiratory pressures. Only one subject had decreased lung compliance and increased recoil pressure after the dive. The others had an increase in compliance and decrease in recoil pressure. There was a significant increase in inspiratory lung compliance (P = 0.041) and a trend for a decrease in lung recoil pressure (P = 0.061). We found no change in forced vital capacity, but decreases in forced expired volume in 1 s (P = 0.049) and forced midexpiratory flow rate (P = 0.009) were noted. There were no changes in maximal respiratory pressures. These findings are opposite to the classical findings associated with pulmonary oxygen toxicity. The results may reflect an increase in surfactant production and turnover as an early adaptive response to hyperoxic stress.

Adult↗