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Biomedical subjects

G Enhorning

Publications and source records attributed to G Enhorning.

62 records · Page 4Linked to original sources
PubMed1977

Photography of peripheral pulmonary airway expansion as affected by surfactant.

Edges of excised lungs from twenty 27-day-old rabbit fetuses were photographed as tracheal pressure was raised and air entered alveoli. Lungs from two littermates were expanded simultaneously with pressure up to 50 cmH2O. The effect of surfactant (SA) on peripheal airway expansion was assessed by depositing 25 mul of SA suspension in the trachea of one pair of lungs. The suspension was obtained by washing the lungs of young adult rabbits and concentrating the SA by centrifugation. In 9 of the 10 experiments, the SA-treated lung was the first to become expanded. When pressure was lowered to 10 or 0 cmH2O, peripheral airways of treated lungs usually maintained expansion; air in control lung alveoli disappeared, or was trapped. High surface tension tended to collapse the cylindrical respiratory bronchiole rather than the spherical alveolus, causing air trapping, if the radius of the cylinder was less than half of the sphere. SA lessened collapsing tendency in the respiratory bronchiole.

Animals↗
PubMed1977

Pulsating bubble technique for evaluating pulmonary surfactant.

Surface tension is determined with an apparatus which records pressure across the surface of a bubble, expanded in the sample liquid and communicating with ambient air. The disposable sample chamber, with a volume of 20 microliter, communicates with a pulsator and a pressure transducer. The volume displacement of the pulsator's moving piston is hydraulically geared down 1,000 times, which gives the pulsator a stroke volume of 0.43 microliter. When this volume is moving into the sample chamber, it causes the bubble radius to change from a maximum of 0.55 mm, accurately measured through a microscope, to a minimum of 0.4 mm. The pulsator speed is usually 20 rpm, but it can be changed from 0.02 to 80 rpm. From the known pressure gradient across bubble surface, and bubble radius, surface tension is calculated with the law of Laplace.

Animals↗
PubMed1977

Oxygen consumption of the newborn rabbit treated with pulmonary surfactant.

A method is described for measuring oxygen consumption of small animals. It was used for 151 newborn rabbits delivered on the 27th, 28th, 29th, and 30th day of gestation. Half of the neonates were given a pharyngeal deposition of a concentrated surfactant (SA) suspension prior to their first breath. The remaining neonates served as controls. The survival rate among the immature rabbits treated with SA was significantly higher. The treatment did not affect oxygen consumption in any age-group. With increasing maturity, the neonates consumed more oxygen, and the controls delivered on the 30th day of gestation consumed 29.6 +/- SEM 4.2 ml oxygen per kilogram and minute.

Age Factors↗
PubMed1975

Radiologic evaluation of the premature newborn rabbit after pharyngeal deposition of surfactant.

Premature rabbit fetuses were delivered by hysterotomy and, prior to the first breath, a concentrated homologous surfactant suspension was deposited in the pharynx. With repeated radiograms, the effect of this treatment was studied during the first two hours of extrauterine life. The lung aeration was quantitated with densitometry, and the chest expansion was assessed by measuring the inferior angle formed by the fourth ribs. In comparison with control animals, the treated animals demonstrated a greater chest expansion, and their lungs were significantly better aerated. Clinical application has to await further studies.

Absorptiometry, Photon↗
PubMedDate not supplied

Whole-body plethysmography, does it measure tidal volume of small animals?

A whole-body plethysmograph was used for mice. The increase in pressure caused by each inhalation was equivalent to the increase that could be calculated to result from heating and humidification of the inhaled air. However, comprehending that a drop in temperature and humidity would cause an abrupt pressure decline during exhalation was difficult. Pressure changes in the plethysmograph were also studied with an artificial chest, modeling the respiratory mechanics, but without the "inhaled" air being heated or humidified. The "chest" consisted of a metal bellows oscillated by a stepper motor 25 to 175 times per minute. Hereby air (0.05 to 0.20 mL) moved in and out of the bellows. The air passed through a polyethylene tube, the length of which was proportional to "airway resistance" and varied from 5 to 35 cm. It was found that the pressure oscillation was affected not only by "tidal volume" of the mechanical chest but also by "respiratory rate" and by "airway resistance." We concur with previous investigators that the plethysmograph pressure reflects alveolar pressure and that fluctuations cannot be explained by changes in temperature and humidity. Accordingly, tidal volume can only be qualitatively and not quantitatively assessed.

Animals↗