Prenatal starvation in the guinea pig causes reduced pulmonary diffusing capacity and retarded alveolarization among neonates. To study the impact of such starvation on biochemical and mechanical properties of the neonatal lung, pregnant guinea pigs were fed ad libitum throughout gestation or starved with 50% rations during their last trimester. ...

Severe respiratory insufficiency was induced in adult guinea pigs by repeated lung lavage. The animals were then ventilated for 75 min with 100% O2, insufflation pressure 28/6-8 cmH2O (2.7/0.6-0.8 kPa), frequency 30/min, and 33% inspiration time. One group of animals (I) was treated with protein-depleted porcine surfactant, prepared by a ...

Whole cell and membrane deformability are essential for red blood cell (RBC) survival and for effective blood flow. Neonatal RBCs display several specific properties (eg, large size, high hemoglobin F) that could influence their deformation characteristics and contribute to their shortened life span. The present study was designed to compare ...

We compared the hemodynamic status and left ventricular (LV) performance in 7 twin pairs of preterm lambs delivered at 124 days gestational age (83% of term gestation) and ventilated by either conventional ventilation (CV) or high frequency ventilation (HFV) at 15 Hz. The lambs were treated with suspensions of natural ...

The use of high oxygen concentrations and high mean airway pressures during mechanical ventilation of premature newborn infants with respiratory distress syndrome leads in 20%-30% of the survivors to chronic lung disease. This study explores if exogenous polyethylene glycol conjugated superoxide dismutase (PEG-SOD) and catalase (PEG-CAT) mitigate oxygen toxicity in ...

Pulmonary surfactant (PS) is capable of lowering surface tension at an air-water interface to less than 10 dynes/cm. This property of PS is believed to be important for normal lung function. We tested the detergent Tween 20, which cannot lower surface tension at an air-water interface to less than 25 ...

The time course of lung injury and recovery from a sublethal exposure to 100% O2 was investigated in adult rabbits. Animals were exposed to 100% O2 for 64 h and then returned to room air for varying periods of time up to 200 h. By the end of the exposure ...

Twelve sets of twin lambs were delivered prematurely by cesarean section at 133-136 days gestational age and ventilated for 3 h with either high-frequency oscillation (HFO) or conventional mechanical ventilation (CMV). Blood gases and pH values were monitored at 30-min intervals, and ventilator settings were adjusted to maintain CO2 partial ...

At a gestational age of 27.9 days, pregnant rabbits were infused with enprofylline, a new xanthine with potent antiasthmatic effects. Following a priming dose of 5 mg/kg, 20 mg/kg were infused over a 2-h period. Controls received Ringer's solution. On completion of the infusion, the fetuses were delivered and the ...

The role of prostaglandins (PG) in the pulmonary hypertension associated with high-frequency oscillatory ventilation (HFOV) was investigated in 7 pentobarbital-anesthetized dogs. The magnitude and time course of the mean pulmonary artery pressure (PAP) changes induced by HFOV (20 Hz) was quantified before and after PG-production blockade with 15 mg/kg indomethacin ...

High-frequency oscillation (HFO) appears to be an alternate, less traumatic mode of ventilating surfactant-deficient patients, because conventional (mechanical) pressure-limited ventilation (CMV) compromises cardiac function at high mean airway pressures. We compared systemic cardiac output and its distribution during HFO and CMV in ten adult rabbits rendered surfactant deficient by repeated ...

Immature newborn rabbits, delivered on day 27 of gestation, were ventilated artificially for 60 min, with or without previous treatment with natural surfactant. Insufflation pressure was adjusted to maintain an average tidal volume of about 10 ml/kg. All animals received, before the onset of ventilation, 125I-labeled albumin via the airways ...

We measured lung clearance of aerosolized technetium-labeled diethylenetriamine pentaacetic acid (99mTcDTPA) as an index of alveolar epithelial permeability in rabbits exposed to cigarette smoke. Eighteen rabbits were randomly assigned to 3 equal-size groups: control, all smoke exposure (ASE), and limited smoke exposure (LSE). Cigarette or sham smoke was delivered by ...

As a prelude to clinical trials with a bovine surfactant (surfactant TA), in human infants with hyaline membrane disease, pulmonary and hemodynamic changes following its instillation in premature baboons were investigated. Baboons, delivered by cesarean section at 141 +/- 3.5 days (mean +/- SD, 77% gestation), were provided with intensive ...

A marked increase in sympathoadrenal activity at birth has been described in animals and humans. Studies to determine whether the magnitude and duration of the catecholamine surge at birth in preterm lambs is similar to full-term lambs were undertaken using an acutely exteriorized fetal lamb. To maintain a physiologically stable ...

To evaluate the effect of meconium on pulmonary surface tension properties, the mechanics of 30 excised, separated canine pulmonary lobes were studied. Meconia were blended in normal saline to produce solutions of 10% and 20%. Solutions were filtered to remove large particles and instilled endobronchially into the canine lobes. The ...

The effect of pressure on the lipid dynamics of the rat lung surfactant was studied in liposomes made of the natural lung surfactant of the rat and of model phospholipid mixture. The determined parameter was the lipid microviscosity, monitored by the fluorescence polarization of the probe 1,6-diphenyl-1,3,5-hexatriene. Osmotic pressure of ...

Rabbits exposed to paraquat develop interstitial pneumonitis. A sublethal dose of paraquat (PQ) solution (250 mg/100 ml) was aerosolized by ultrasonic nebulization for one hour to rabbits in a closed vented chamber on two occasions with a five-day interval between exposures. Groups studied included saline-exposed (N = 4); saline-exposed, methylprednisolone ...

The effect of the detergent dioctyl sodium sulfosuccinate on pulmonary extravascular water volume (PEWV) was studied in adult anesthetized mongrel dogs. The detergent was dissolved as a 1% solution in a vehicle of equal volumes of 95% ethanol and normal saline and administered by ultrasonic nebulizer attached to the inspiratory ...

A natural surfactant with low protein content (1%) was prepared by a sequence of cold centrifugation, heating to 90 degrees C, sucrose-gradient centrifugation, and extraction with chloroform:methanol. Some of the material was enriched with dipalmitoylphosphatidylcholine (DPPC) and unsaturated phosphatidylglycerol (PG) to relative concentrations of 56% and 10%, respectively. The in ...

Animal experiments and clinical trials have shown that the neonatal respiratory distress syndrome (RDS) can be treated effectively by surfactant replacement via the airways. This treatment facilitates the resorption of fetal pulmonary fluid, promotes uniform air expansion of the lungs, enhances gas exchange, reduces the protein leak across the alveolar ...

The mechanical properties of the newborn piglet gallbladder were evaluated in both the stimulated and unstimulated states. The pressure-volume relationships, compliance, and the estimated active tension of the gallbladder were determined in 10 newborn piglets (2-7 days of age). Agonist stimulation was achieved by administration of histamine (25 micrograms/kg/h) and ...

By using adult rabbits in which the lung surfactant had been reduced by repeated whole-lung lavage, we examined the effects of surfactant supplement and positive end-expiratory pressure (PEEP). The rabbits were anesthetized with pentobarbital sodium and mechanically ventilated with pure O2. Surfactant that was extracted from pigs' lungs was supplemented ...

Saline or triiodothyronine (T3) (50-1000 micrograms) was injected into the amniotic sac of 17 pregnant ewes under general anesthesia at 130 days gestation. Forty-eight h later, the lambs were delivered by hysterotomy. Cord plasma T3 and cortisol and amniotic fluid T3 were assayed, and the maturity of the fetal lung ...

Surfactant phospholipid metabolism was studied in anesthetized rabbits ventilated with high-frequency oscillation at a frequency of 5 Hz and a mean airway pressure of 5 cm H2O. Blood gases were normal although some atelectasis was evident after 1 h. The static compliance of the lungs and amount and composition of ...

High-frequency jet ventilation (HFJV) was compared with conventional ventilation (CV) after surfactant displacement with diocytyl sodium sulfosuccinate (OT) via ultrasonic nebulization. After aerosol delivery, dogs were separated into 3 groups and followed for 2 h. Ventilator settings were not changed in group I (CV) and group II (HFJV) after OT ...

Prenatal asphyxia resulting in hypoxia, hypercarbia and amniotic fluid aspiration reduces the synthesis of the pulmonary surfactant. Using 135-day fetal lambs we studied the in utero effects of hypercarbic acidosis alone on fetal breathing activity, excised lung pressure-volume relationships and lamellar body (LB) surfactant disaturated phosphatidylcholine (DSPC) pool size and ...

In six open-chest dogs, unilobar pulmonary edema was induced by injection of oleic acid into a lower lobe pulmonary arterial branch. Two hours later, intermittent positive-pressure ventilation (IPPV) and high-frequency oscillatory ventilation (HFOV) at matched mean alveolar pressures (MAP) were compared at 30-min intervals. The edematous lobar venous admixture (Qva/QT) ...

The effect of hyperoxia (greater than 95%) on surfactant phospholipid recovered by lavage and pulmonary pressure:volume characteristics was studied in rabbits exposed from birth through 4 days of life. Decreased surfactant phospholipid (microgram/mg dry lung weight) in the airways was observed as early as 6 h and persisted through 96 ...

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, ...

We describe a method of monitoring continuously subarachnoid pressure in the severely asphyxiated newborn by a percutaneously placed catheter. Five infants were studied for a total of 180 hours and although opening pressures were not appreciably raised in any, maximum pressures were above 20 mmHg in four infants and reached ...

The fetal lung responds to beta-receptor agonists with a release of surfactant from type II alveolar cells, if such stimulation were intense or long-lasting, the supply might become depleted and, while the supply is being restored, there could be a surfactant deficiency. With experiments on pregnant rabbits, this hypothesis was ...

The secretion of total phospholipid in postmortem in situ lungs of newborn rabbits was examined using the technique of lung lavage after an initial lavage procedure, and then after a period of static air inflation at 30 cm H2O pressure for 45 min. There was a significant reduction in the ...

The effect of tracheal instillation of surface-active mixtures in premature lambs was studied as an animal model of exogenous surfactant replacement therapy for the respiratory distress syndrome (RDS). Specific mixtures studied were 7:3 (molar ratio) dipalmitoyl phosphatidylcholine (DPPC):egg phosphatidylglycerol (PG) and extracted mixed lipids (with 1% protein) from cow lung ...

Cardiopulmonary function was evaluated in very preterm lambs (106 +/- 0.7 S.E. days gestation, 1.66 +/- 0.12 S.E. kg birth weight) during fluorocarbon ventilation. Lambs were delivered by cesarean section after epidural anesthesia. Indwelling arterial, venous, and tracheal cannulae were placed before clamping the cord. Lambs were then mechanically ventilated ...

We have investigated the effects of substituting phosphatidylinositol (PI) for phosphatidylglycerol (PG) on the functional properties of rabbit lung surfactant. We gave oral 10% glucose solution for 3 days to 11 rabbits and 10% inositol to 12 others. Lung lavage surfactant phospholipids were normal in both groups, except that PG ...

After delivery by cesarean section at 133-136 days gestational age, 18 lambs were supported with infant ventilators. Peak inspiratory pressure was the only ventilator setting that was changed in an attempt to normalize PCO2. The lambs were retrospectively divided into two groups based on their respiratory status before treatment. Ten ...

We investigated changes of alveolar stability and phospholipids in the pulmonary surfactant in case of acute pancreatitis induced in rats. Alveolar stability was examined by recording the pressure-volume relationship. The lung volumes during deflation decreased significantly at equivalent transpulmonary pressures, particularly when the pressure was lower than 6 cm H2O. ...

Arterial PO2 and PCO2 obtained with 2 modes of mechanical ventilation were compared in 5 premature monkeys with hyaline membrane disease (HMD) during the first 7 h of life. High-frequency oscillation (HFO) (10 Hertz) was compared with conventional positive-pressure ventilation (CMV) by matching the mean airway pressure generated by the ...

Studies in vitro and in vivo of the alveolar epithelial membrane, which show it can normally be characterized as having a "pore radius" of 0.5 to 1.5 nm, have been presented frequently over 20 years in a number of species (2, 3, 6, 8, 12). The alveolar epithelium appears to ...

An experimental model was designed to investigate the role of meticulous intramedullary lavage in the prevention of the blood-gas and hemodynamic changes that have been documented to occur during cemented arthroplasty. Twenty-one adult mongrel dogs were divided into two groups. One group had the medullary canal thoroughly lavaged prior to ...

We applied high-frequency oscillatory ventilation (HFOV) of low amplitude to the pleural surface of the isolated rat lung (IPL) perfused at 10 ml X min-1 with Krebs bicarbonate containing 4.5% albumin (hematocrit 34%). Lung volume was held constant by a continuous positive airways pressure (CPAP) of 5 cmH2O. Varying CPAP ...

Five dogs have been embolized by air infusion into the venous system, then sacrificed and the pulmonary vasculature isolated by ligatures while ventilation was maintained for a further hour. In a sixth animal, the embolization was omitted. The lungs were back-perfused with plasma from the same dog and successive aliquots ...

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 ...

A porous membrane has been synthesized from a fine-weave cotton fabric carboxylated to simulate the fixed negative charges in the alveolar wall. When this membrane is treated with pulmonary surfactant in physiological concentrations, especially DPL, it loses its fluid permeability and can support a pressure of physiological saline of over ...

Thirty-four Western mixed breed lambs were delivered prematurely at 120 days gestational age (term = 150 days). Four lambs were sacrificed at birth, and four lambs were sacrificed with the onset of respiratory failure (PCO2 greater than 80 torr) at about 30 min of age. The remaining lambs were treated ...

Bronchiolar epithelial lesions, similar to those in human hyaline membrane disease (HMD), can be induced by artificial ventilation of newborn rabbits, delivered on day 27 of gestation. As verified by electron microscopy, these epithelial lesions develop within only 1-5 min of artificial ventilation. Tracheal instillation of natural surfactant at birth ...

The development of sucking response was investigated in 30 clinically normal infants from 1 or 5 minutes postbirth until their first feeding 4 hours later. Maximum sucking pressures were measured with a research nipple attached to a portable electronic suckometer. Mean suction (negative pressure) began at 5 Torr at birth, ...

When a pressurized inhalation aerosol is used, a high loss of drug substance occurs in the upper respiratory tract. This is explained by the rather slow propellant evaporation after the initial aerosol generation, and by the high initial aerosol velocity. Indirect measurements can be performed with a view to obtaining ...

The use of pressurized aerosol inhalers was assessed in a total of 1173 out-patients attending hospital during a three month period. One hundred and thirty-five patients already being treated with drugs by inhalation were found to have a poor inhaler technique, even though most had received instruction on how to ...