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Biomedical subjects

G Grossmann

Publications and source records attributed to G Grossmann.

At least 91 records · Page 5Linked to original sources
PubMed1985

Surfactant treatment and ventilation by high frequency oscillation in premature newborn rabbits: effect on survival, lung aeration, and bronchiolar epithelial lesions.

Premature rabbit neonates delivered at gestational age 27 days were ventilated by high frequency oscillation for 60 min with 100% O2, using a frequency of 7-8 Hz, 50% inspiration time and mean airway pressures of 6-8 cm H2O. Twenty-five animals received bovine surfactant (2 ml/kg body weight; phospholipid concentration 85-100 mg/ml) in the tracheal cannula before onset of ventilation, and 22 littermates served as controls. In the surfactant-treated group, average tidal volume was about 10 times larger than in controls, yet only 15% of the estimated dead space. Judged from ECG recordings, the treated animals also had a much higher survival rate: 96 versus 5% (p less than 0.001). Morphometrically, mean alveolar volume density was increased in the surfactant-treated animals in comparison with controls: 0.65 +/- 0.08 versus 0.37 +/- 0.08 (means +/- SD; p less than 0.005). Bronchiolar epithelial lesions were found in all control animals and were severe in almost all cases. In the surfactant-treated group, epithelial lesions were absent in 12, mild in 11, and fairly prominent in two animals. We conclude that after treatment with surfactant, the premature newborn rabbit can be ventilated adequately with high frequency oscillation at comparatively low mean airway pressures and that surfactant replacement effectively reduces the development of epithelial lesions in conducting airways during high frequency oscillation.

Animals↗
PubMed1984

Lung expansion in premature newborn rabbits treated with emulsified synthetic surfactant; principles for experimental evaluation of synthetic substitutes for pulmonary surfactant.

This paper presents a sequence of tests for experimental evaluation of potential substitutes for pulmonary surfactant. Differential thermal analysis and the pulsating bubble technique were applied to identify an emulsified mixture of synthetic lipids with properties similar to those of natural surfactant. Instilled into the airways of premature newborn rabbits, this emulsion improved pulmonary pressure-volume characteristics and enhanced lung-thorax compliance during artificial ventilation. However, the in vivo effect was inferior to that of natural surfactant, especially as the emulsion failed to prevent the development of bronchiolar epithelial lesions.

Animals↗
PubMed1984

Improved lung-thorax compliance in the premature rabbit neonate after treatment with dibuturyladenosine-3':5'-cyclic monophosphate.

Premature rabbit neonates, delivered on day 28 of gestation, were treated with a single dose of dibuturyladenosine-3':5'-cyclic monophosphate (cyclic AMP), 300 mg/kg, immediately after delivery, saline-injected litter-mates serving as controls. All animals were kept in body plethysmographs and ventilated artificially with 100% oxygen for 1 h, with a maximal tidal volume of 10 ml/kg body weight. Lung-thorax compliance was significantly improved in animals treated with cyclic AMP, both 30 and 60 min after onset of ventilation (0.92 +/- 0.09 vs. 0.59 +/- 0.08 ml/cm H2O.kg and 0.96 +/- 0.09 vs. 0.53 +/- 0.08, p less than 0.005), but there was no improvement in alveolar air expansion, evaluated histologically. Phosphatidylglycerol was absent in alveolar wash from all control animals, but present in 3 of the 8 pooled samples from the animals treated with cyclic AMP; this difference was not statistically significant, however.

Animals↗
PubMed1983

Effect of terbutaline on lung mechanics and morphology in the preterm rabbit neonate.

Lung morphology, surface properties of fetal pulmonary fluid, and lung mechanics during spontaneous breathing were studied in preterm newborn rabbits after antenatal administration of terbutaline (0.1 mg). The histological evaluation of lung sections revealed increased amounts of granular eosinophilic and sudanophilic material in the terminal airspaces. The amount of fetal pulmonary fluid was decreased in terbutaline-treated animals; the fetal pulmonary fluid also showed improved surface properties, evaluated by the pulsating bubble technique. Increased dynamic lung compliance without altered air-way resistance was found in terbutaline-treated animals during the first 30 min after onset of breathing. This report demonstrates that terbutaline has an initial beneficial influence on the preterm neonatal lung, probably due to release of preformed surfactant into the alveolar spaces and to dehydration of the lung.

Animals↗
PubMed1982

Combined effects of surfactant substitution and prolongation of inspiration phase in artificially ventilated premature newborn rabbits.

Premature newborn rabbits, delivered by hysterotomy on day 27 of gestation, were tracheotomized at birth, kept in body plethysmographs, and subjected to pressure-generated ventilation at a working pressure of 25 cm H2O, 100% O2, and frequency 40/min. Thirty-seven animals received 50 microliters of heterologous surfactant (phospholipid content 40 mg/ml) via the tracheal cannula before onset of artificial ventilation, eight were ventilated with a positive end-expiratory pressure (PEEP) of 6 cm H2O, and 44 served as controls. All animals were ventilated in a randomized sequence of 2-min periods with 20, 40, 60, or 80% inspiration time. After the experiment the trachea was clamped at end-inspiration and the lungs fixed by immersion in formalin. Plethysmograph recordings of tidal volume revealed that lung-thorax compliance was low in control animals, even at inspiration time 80% (mean +/- S.E. = 0.17 +/- 0.03 ml/cm H2O X kg). In animals treated with surfactant or PEEP, compliance was significantly improved at all ventilator settings. The highest mean compliance values, obtained at 60% inspiration time were 0.91 +/- 0.07 and 0.73 +/- 0.14 ml/cm H2O X kg in surfactant- and PEEP-treated animals, respectively. Compliance of surfactant-treated animals was significantly higher than that of PEEP-treated animals at inspiration time 40% (0.85 +/- 0.07 versus 0.52 +/- 0.13 ml/cm H2O X kg; P less than 0.05). The relative volume of the alveolar compartment, determined morphometrically in histologic sections and expressed as the alveolar expansion index (Ia), was significantly higher in surfactant-treated animals than in controls (1.60 +/- 0.12 versus 0.74 +/- 0.06; P less than 0.005), but not improved in animals ventilated with PEEP. In animals receiving surfactant, Ia increased with the duration of the inspiration phase, from 0.99 +/- 0.10 at 20% to 1.95 +/- 0.22 at 80% inspiration time. There was also histologic evidence of enhanced recruitment of aerated alveoli in surfactant-treated animals ventilated with prolonged inspiration time.

Animals↗
PubMed1981

Lung compliance and alveolar expansion in the artificially ventilated premature newborn rabbit after maternal treatment with ambroxol.

Premature newborn rabbits were delivered on day 27 of gestation, with or without antenatal treatment with ambroxol (50 mg/kg/day in maternal injections, on days 24-26). The animals were tracheostomized, kept in body plethysmographs at 35 degrees C, and ventilated artificially for 10 min with 100% oxygen, insufflation pressure 30 cm H2O, frequency 40/min, and varying inspiration time (20, 40, 60, or 80%). Lung-thorax compliance increased with inspiration time in both ambroxol-treated animals and controls, but there was no difference in compliance between treated and non-treated litters. Alveolar expansion, evaluated morphometrically in histological sections, was enhanced in ambroxol-treated animals ventilated with prolonged inspiration phase (60 or 80%); such a difference was not found in the on-treated group. This suggests that antenatal treatment with ambroxol might have a stimulating effect on the synthesis and/or release of factors improving alveolar stability in the premature lung.

Ambroxol↗
PubMed1981

Surfactant treatment in experimental hyaline membrane disease.

Premature newborn rabbits obtained by hysterotomy on day 27 of gestation were ventilated artificially under standardized conditions, serving as experimental model of neonatal hyaline membrane disease. Natural surfactant with a phospholipid concentration of approximately 8 mg/ml was administered as 50-microliter doses after 10 min of ventilation and at subsequent 30-min intervals. Initial values for lung-thorax compliance were significantly improved following two doses of surfactant, whereas compliance levels of non-treated littermates remained unchanged. Treatment with surfactant resulted in increased alveolar air expansion. Bronchiolar epithelial lesions were present in both surfactant-treated animals and controls, but the severity of these lesions was clearly reduced after surfactant treatment. We conclude that surfactant substitution is an effective treatment in experimental hyaline membrane disease, even when given after an initial period of artificial ventilation.

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