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Biomedical subjects

A Hauge

Publications and source records attributed to A Hauge.

At least 55 records · Page 3Linked to original sources
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↗
PubMed1977

Small airway constriction and closure after induced intravascular platelet aggregation.

The aim of this study was to investigate the function of the peripheral airways after intravascular platelet aggregation induced by i.v. infusions of collagen in open chest anesthetized cats, ventilated with constant tidal volume. Lung compliance was examined under static conditions (stat CL) and under dynamic conditions (dyn CL) at ventilation frequencies of 5, 24 and 50/min. In the control situation dyn CL 24 was approximately 90% of stat CL. Collagen infusions resulted in a pronounced frequency-dependence of lung compliance. When dyn CL 24 had decreased by approximately 40% a reduction in stat CL could also be detected. When dyn CL 24 decreased even more a concurrent reduction in stat CL was evident. These findings indicate that the initial event after induced intravascular platelet aggregation is small airway constriction. With more pronounced changes airway closure and reduction in lung volume occurs. We suggest that these functional changes in peripheral airways result in the impaired gas exchange known to occur after intra-vascular platelet aggregation.

Animals↗
PubMed1977

Alveolar pressure and lung volume as determinants of net transvascular fluid filtration.

We have investigated the influence of changes in alveolar pressure (PAlv) and in lung volume on the net transvascular fluid filtration rate (FFR). The preparation was isolated, perfused zone III rabbit lungs. In observation periods the outflow pressure was kept constant at a level generally causing net filtration. All pressures were measured relative to atmospheric. FFR was measured by continuous monitoring of preparation weight. Elevation of Palv at constant lung volume caused reversible reductions in FFR, also at constant capillary hydrostatic pressure (Pa-V less than 2 Torr). Increases in lung volume at constant PAlv caused reversible increases in FFR. When both PAlv and Ptp were increased a reduction in FFR was seen in the majority of cases. We conclude that at constant pulmonary arterial pressure, the size and the direction of the influence of positive airway pressure on FFR depend on the relative change in lung volume and in alveolar pressure per se. Under the present experimental conditions a rise in PAlv will be transmitted to interstitial fluid pressure and affect the transvascular fluid balance.

Animals↗
PubMed1977

[Experiences with various antireflux operations (author's transl)].

One hundred and thirty-eight antireflux operations in 94 patients are reported from 1964 to 1974. Bischoff's method was used 44 times with 63% successful results; Lich/Grégoir's method 38 times with 77% success; and Politano/Leadbetter's method 50 times with 92% success. Indications are briefly investigated.

Evaluation Studies as Topic↗
PubMed1976

Reduction of pulsatile hydraulic power in the pulmonary circultation caused by moderate vasoconstriction.

Vascular input impedance and associated hydraulic power was measured in rabbit isolated lungs. The study was focused on changes in impedance and in pulsatile hydraulic power during relaxation and contraction of vascular smooth muscle. Pulsatile power was found to be at a minimum when smooth muscle tone was such that the pulmonary arterial pressure was in the physiological range, and increased both when the vessels were relaxed and further constricted. Input impedance was found to be determined mainly by the large, proximal ('extra-alveolar') arteries.

Acetylcholine↗
PubMed1976

Influence of moderate vasoconstriction on the wave reflection properties of the pulmonary arterial bed.

Increased transmural pressure in the pulmonary arterial bed may reduce vascular input impedance and reduce hydraulic power linked to pulsatile blood flow. Vascular impedance and pulsatile hydraulic power (Wp) levels of isolated perfused rabbit lungs were compared after similar rises of pulmonary arterial pressure (PAp), induced either by vasoconstriction or by left atrial pressure (LAp) elevation. Resulting Wp levels were significantly smaller after vasoconstriction than LAp elevation. Wp showed a minimum level at physiologic PAp (about 20 cm H2O) irrespective of the cause of PAp elevation. Pressure pulse wave reflection coefficient (see article) was calculated for control and test situations, and was found to be approximately doubled after vasoconstriction. Only minor changes in (see article) were found after LAp elevation. Accordingly, moderate vasoconstriction (resulting PAp approximately 20 cm H2O) caused a backward traveling pressure wave of high amplitude, appearing in counter-phase to the forward pressure wave at the input site. The total pressure wave amplitude was thereby markedly lowered, resulting in a reduced Wp level. We assume that this effect of moderate vasoconstriction may be one reason for the existence of vascular smooth muscles in the pulmonary arteries.

Acetylcholine↗
PubMed1975

The pulmonary vasoconstrictor response to hypoxia: effects of inhibitors of prostaglandin biosynthesis.

The main purpose of the present work was to determine whether prostaglandins (PGs) synthetised in the lungs mediate the vasoconstrictor response to acute alveolar hypoxia. Isolated and ventilated lungs of rats were perfused at 37 degrees C with homologous blood at constant-volume, pulsatile inflow, and pressor responses to 3 min periods of standardized ventilation hypoxia recorded. Indomethacin, sodium meclofenamate and acetylsalicylic acid (all 100 mug/ml), which are potent inhibitors of PG biosynthesis, did not reduce the hypoxic vasoconstrictor response. Sometimes they even enhanced this response. We conclude that PGs do not mediate the hypoxia-induced vasoconstriction. We suggest that vasodilatory PGs might act to reduce and modify pulmonary arterial hypertension due to hypoxia.

Animals↗
PubMed1975

Interrelations between pulmonary liquid volumes and lung compliance.

We have investigated the relative effects of lung edema and of increases in pulmonary blood volume (PBV) on lung compliance (CL), and also the effects of selective elevations of pulmonary arterial (Ppa) and left atrial (Pla) pressures on PBV and on CL, using an isolated, perfused, and ventilated rabbit lung preparation. Lung weight was continuously recorded. A step rise in Pla at constant flow caused a rapid rise in PBV accompanied by an immediate fall in CL. With maintained high vascular pressures interstitial edema accumulated with no further fall in CL. Not until 3 times the normal amount of extra-vascular fluid had accumulated did a further, secondary reduction in CL occur. When Ppa was elevated to the same level by 1) a rise in flow and 2) a rise in Pla, the latter type of experiment gave 3-5 times larger increases in PBV. Pla elevations with or without rise in Ppa (flow adjusted) gave almost the same rises in PBV. The fall in CL was related to rises in PBV regardless of how such rises were obtained. Our conclusion is that increases in PBV, but not accumulation of interstitial edema, reduced CL in this preparation.

Animals↗