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Results for “Lung Compliance”

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At least 19 recordsLinked to original sources
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↗
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↗
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↗
PubMed1976

Static and dynamic lung compliance in asthmatic symptom-free children.

The static lung compliance was studied in 27 symptom-free asthmatic children, 6-14 years old. The technique of so-called end-expiratory compliance measurement as well as that of the 'zero volume' in the balloon at barometric pressure, used in this study, have been previously discussed. The static lung compliance value is larger than the dynamic lung compliance value, this difference being larger in asthmatic than in healthy children. This difference is explained by higher static lung compliance values in asthmatic than in healthy children, whereas dynamic lung compliance values are only slightly lower in the group of asthmatic patients compared to healthy children. Static lung compliance per unit of lung volume (specific static lung compliance) is identical in both groups. Static recoil pressure at 80% of total lung capacity (TLC) is similar in asthmatic and healthy children. However, in symptom-free asthmatic children with hyperinflated lungs [functional residual capacity (FRC) higher than 25% of predicted value and FRC/TLC ratio higher than 0.45], static recoil pressure at 80% TLC is lower than the predicted value, this difference being not significant.

Adolescent↗
PubMed1979

Lung compliance and cholesterol during stellate ganglion stimulation.

The relationships between lung compliance, surface tension, and cholesterol during stimulation of the sympathetic nervous system were studied in 28 cats. Cats were anesthetized with ketamine hydrocholoride, injected with one of five sympathetic blocking agents or inhibitors and injected with isoprotenol. The left stellate ganglion was then stimulated electrically for 5 min. We found that stimulation decreased lung compliance and increased the surface tension and the cholesterol concentration in the lung wash fluid. Alpha blockers (phentolamine and phenoxybenzamine) and catecholamine inhibitors (reserpine and guanethidine) prevented these changes, but the beta blocker practolol did not. In additional experiments airway resistance, functional residual capacity and lung weights did not change during stellate stimulation. The results from the present study suggest that stellate ganglion stimulation resulted in decreased lung compliance with an increased surface tension and cholesterol in lung wash fluid.

Animals↗
PubMed1979

Improved oxygenation and lung compliance with prone positioning of neonates.

Fourteen intubated infants recovering from neonatal respiratory disease had arterial blood gases and lung mechanics measured in the supine position and in two variants of the prone position. Prone positioning resulted in significant increases in mean (+/- SEM) arterial oxygen tension (Pa(o2 70.4 +/- 2.5 to 81.1 +/- 4.4mm Hg), dynamic lung compliance (1.7 +/- 0.24 to 2.55 +/- 0.37 ml/cm H2O),and tidal volume (8.6 +/- 1.0 to 10.5 +/- 1.2 ml) when all prone values were compared to supine values. Prone positioning with the abdomen protruding freely, when compared to all supine values, was associated with significantly increased dynamic lung compliance and tidal volume. Values for prone-abdomen free were not significantly different from values for prone-abdomen restricted. This suggests that there are clinical benefits from prone positioning in neonates recovering from respiratory disease.

Acid-Base Equilibrium↗
PubMed1979

The effects of H1- and H2-receptor agonists and antagonists on total lung resistance, dynamic lung compliance and irritant receptor discharge in the anaesthetized dog.

1 The effects of histamine and 4 methylhistamine (i.v.) alone, and in the presence of chlorpheniramine or cimetidine, on total lung resistance (RL), dynamic lung compliance (Cdyn) and irritant receptor activity have been studied in dogs anaesthetized with chloralose. 2 Histamine produced dose-related increases in RL and irritant receptor activity with associated falls in Cdyn which were blocked by chlorpheniramine but unaffected by cimetidine. 3 4 Methylhistamine produced small insignificant changes in RL and Cdyn and small significant increases in irritant receptor activity which were reduced with chlorpheniramine but unaffected by cimetidine. 4 The results suggest that histamine increases irritant receptor activity, either directly or indirectly, via H1-receptors.

Animals↗
PubMed1979

Effect of an acute increase in cerebrospinal fluid pressure on lung compliance in the rabbit.

Cerebrospinal fluid pressure (Pcsf) was increased acutely by the injection of normal saline into the cisterna magna of anaesthetized rabbits to values which interrupted cerebral flow. When increased Pcsf was maintained for a minimum of 3 min, static lung compliance decreased and lung weight (after sacrifice) increased without marked change in arterial blood-gas tensions. The magnitude of the increase in Pcsf did not affect the change in compliance and weight. There was marked unexplained metabolic acidosis. The pulmonary findings may result from a massive shift of blood from the systemic to the pulmonary circulation leading to increased permeability of the interendothelial junctions of the pulmonary capillaries.

Acidosis↗
PubMed1977

Circadian rhythms in lung resistance and dynamic lung compliance of healthy children. Effects of two bronchodilators.

In two groups of healthy children synchronized with a diurnal activity (light-on at 07.00) and a nocturnal rest(light-off at 21.00), lug resistance (R1) and dynamic lung compliance (C1 dyn) were measured at fixed clock hours (07.30, 11.30, 16.30, 22.30). The measurements were performed before and 10 minutes after the inhalation of bronchodilators (a beta-sympathetic stimulating agent (orciprenaline, dose 2 mg) and a vagolytic agent (SCH 1000, doses 80 mug and 200 mug). A circadian rhythm is detected for R1 and C1 dyn and quantified by the cosinor method. R1 and C1 dyn acrophase (peak time in the 24-h scale) are not significantly different for both groups: they are located for R1 at 05.39 and 03.31, for C1 dyn at 09.31 and 12.51. R1 and C1 dyn circadian rhythms are not detectable both after 2 mg orciprenaline and 200 mug SCH 1000 inhalation. This chronopharmacologic effect of the bronchodilators might be considered indirect evidence of a circadian rhythm in the bronchial tone. This latter may be related to circadian changes in neurovegetative activity. A dose-effect difference of the vagolytic agent on R1 at night seems to indicate a relative nocturnal prominence of the vagal tone.

Airway Resistance↗
PubMed1977

Post operative pulmonary compliance.

Lung compliance was studied pre-operatively and post-operatively in a group of patients having abdominal surgery. Lung compliance was shown to be markedly reduced post-operatively especially in the patients with chronic bronchitis.

Abdomen↗
PubMed1977

Effects of decreasing lung compliance with oleic acid on the cardiovascular response to PEEP.

In 12 anesthetized mongrel dogs on a constant volume ventilator, the response of the cardiovascular system to increasing positive end-expiratory pressure (PEEP) was examined before and after inducing acute lung injury with oleic acid. As PEEP was raised to approximately 16 mmHg, lung volume increased by approximately 900 ml before oleic acid and only 350 ml after. Pleural pressure increased by the same amount, indicating that both lung and chest wall compliance decreased with oleic acid. Right atrial pressure, the back pressure to venous return, also increased by the same amount. Although cardiac output at PEEP = 0 was lower after oleic acid, the relative decrements produced by increasing PEEP were the same as before oleic acid.

Animals↗