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Biomedical subjects

D K Buckhold

Publications and source records attributed to D K Buckhold.

9 recordsLinked to original sources
PubMed1987

Enhancement of lung conditioning by acetylcholine in the prevention of respiratory distress syndrome in the preterm fetal lamb.

We exposed 128- to 130-day-gestation fetal lambs by cesarean section leaving the umbilical cord and placenta undisturbed, and we then treated the lungs with pulmonary conditioning (i.e., repeated prolonged inflations to 35 cm H2O, followed by a continuous positive airway pressure of 15 cm H2O). To investigate the added effect of pulmonary vasodilation upon the increase of total compliance and pulmonary oxygen uptake, we also administered acetylcholine intravenously at a rate of 80 micrograms min-1. Eleven of 13 lambs met the endpoint criteria of either compliance (0.5 ml [cm H2O]-1 kg-1; 1 animal), or pulmonary oxygen uptake (6 ml kg-1 min-1; 6 animals), or both (4 animals), and were delivered within 0.6 +/- 0.3 h. This time was significantly (p less than 0.05) shorter than previously seen in similar studies without the infusion of a vasodilator; all animals so delivered survived 24 h of mechanical ventilation in excellent health. We suggest that pharmacologic pulmonary vasodilation, in addition to deep sustained pulmonary insufflation and distension, is an effective and rapid means of transforming stiff immature lungs into lungs that can sustain normal ventilation and gas exchange.

Acetylcholine↗
PubMed1986

Successful treatment of experimental neonatal respiratory failure using extracorporeal membrane lung assist.

A total of 44 preterm fetal lambs at great risk of developing respiratory failure were delivered by Cesarean section, and were then managed on conventional mechanical pulmonary ventilation. Fifteen animals initially fared well, and 14 of these were long term survivors. Twenty-nine other lambs showed a progressive deterioration in arterial blood gases within 30 minutes of delivery, of which 10 lambs were continued on mechanical pulmonary ventilation (20% survival), while the remaining 19 lambs were placed on an extracorporeal membrane lung respiratory assist (79% survival). Extracorporeal membrane lung bypass rapidly corrected arterial blood gas values, and permitted the use of high levels of CPAP instead of the continuation of mechanical pulmonary ventilation at high peak airway pressures. Improvement in lung function was gradual, and predictable. Early institution of extracorporeal respiratory assist using a membrane artificial lung rapidly corrected arterial blood gas values and significantly improved on neonate survival.

Animals↗
PubMed1984

Respiratory distress syndrome in immature lambs. Prevention through antenatal accelerated conditioning of the lung.

We tested the effectiveness of constant distending pressure applied to immature lungs in preventing respiratory distress syndrome. Fetal lambs of 131 to 134 days gestation were delivered by cesarean section, but the umbilical circulation was kept intact for CO2 removal through the natural in situ placenta. The lungs were inflated to a pressure of 35 cm H2O (Group I, 11 animals) or 25 cm H2O (Group II, 14 animals), after which the airway pressure was maintained at 15 cm H2O through apneic oxygenation until total static compliance exceeded 0.5 ml (cm H2O)- 1kg -1. After a mean of 1.1 and 5.7 h, respectively, the animals were delivered and were given mechanical ventilation for 24 h. Twenty-four animals reached this aimed-for compliance and survived the period of mechanical ventilation in excellent health. A control group of fetal lambs was delivered immediately and treated with mechanical ventilation. Three of 10 control animals developed severe respiratory distress syndrome and died; 1 additional animal survived but with central nervous system involvement from severe hypoxia. We conclude that pulmonary inflation to 35 cm H2O pressure, followed by a constant distending pressure of 15 cm H2O, held until compliance reaches 0.5 ml (cm H2O)- 1kg -1, is an important element in the prevention of respiratory distress syndrome.

Animals↗
PubMed1982

Prevention of hyaline membrane disease in premature lambs by apneic oxygenation and extracorporeal carbon dioxide removal.

Hyaline membrane disease is found only in lungs where pulmonary ventilation has been established, i.e. after birth. We delivered eleven fetal lambs of a gestational age of 128-130 days but instead kept their lungs in total apnea and inflated to constant pressure, while removing all metabolically produced carbon dioxide with an extracorporeal membrane lung. Oxygen was provided by the membrane lung, and by apneic oxygenation through the natural lungs. Hence, arterial blood gases remained always normal, without any pulmonary ventilation. After 6-66 h the lungs had sufficiently cleared to allow normal mechanical pulmonary ventilation in 10 our of 11 lambs so treated. In a control group treated with mechanical ventilation alone, five of seven lambs died within the first 24 h of severe hyaline membrane disease.

Animals↗
PubMed1981

Chylomicron metabolism during dietary-induced hypercholesterolemia in dogs.

The metabolism of [1-3H]retinol- and [4-14C]cholesterol-labeled chylomicrons was studied in normal and cholesterol-fed dogs in order to estimate the relative contribution of chylomicron remnant cholesterol to diet-induced hypercholesterolemia. The plasma t 1/2 of intravenously administered Sf greater than 400 chylomicrons, Sf 20-400 chylomicrons, and whole lymph doubly labeled with [1-3H]retinol and [4-14C]cholesterol was not significantly prolonged in hypercholesterolemic recipients. When Sf greater than 400 chylomicrons were administered intravenously, 90% of the radioactivity was cleared from the plasma of both normal and cholesterol-fed dogs within 1 hr and 68 +/- 18% appeared in the liver within approximately 2 hr in normal dogs and 4 hr in hypercholesterolemic dogs. The use of the retinol-labeling technique for intestinal lipoproteins provided evidence that some LDL, but essentially none of the HDLc, was derived from d greater than 1.006 g/ml lymph lipoproteins. The failure of significant radioactivity to accumulate in the plasma compartment of hypercholesterolemic dogs after intravenous administration of doubly labeled chylomicrons and the relatively efficient uptake of radioactivity by the liver indicate that the dietary-induced hypercholesterolemia in dogs is not the result of impaired hepatic removal of chylomicron remnants.

Animals↗
PubMed1977

Cardiovascular response to fentanyl-droperidol and atropine in the dog.

A combination of fentanyl-droperidol was administered intravenously alone or with atropine sulfate (2 doses--0.04 or 0.02 mg/kg of body weight) to determine if stable neuroleptanalgesia could be produced in the dog. Cardiovascular responses were recorded at 5, 15, and 30 minutes. Fentanyl-droperidol given alone caused a significant increase of peripheral resistance and mean arterial pressure at 5 minutes and then a decrease of these values over a postinjection period of 30 minutes. Left ventricular dP/dt increased significantly at postinjection minutes 15 and 30. In dogs given atropine concurrently with fentanyl-droperidol, there was significant increase in heart rate and decrease in stroke volume. Also, there were significant initial increases in diastolic and mean arterial blood pressures, ventricular contractility, and coronary blood flow. The dose of 0.02 mg of atropine/kg seemed optimal for intravenous administration with fentanyl-droperidol in the dog; when the atropine dose was 0.04 mg/kg, large inotropic and chronotropic effects were produced.

Animals↗