Chronic pulmonary hypertension in sheep: temporal progression of lesions.

Scant data exist on the evolution of the lesions of pulmonary hypertension. This study establishes a model in sheep in which the left upper lobe (LUL) was rendered hypertensive by a systemic-pulmonary shunt while the rest of the pulmonary circulation remained normotensive. By examining lung tissue at 2 months and 1 1/2 years after shunting, we sought the temporal progression of pulmonary hypertensive lesions.

Effects of nordihydroguaiuretic acid on sulfidopeptide leukotriene activity and hypoxic pulmonary vasoconstriction in the isolated sheep lung.

Sulfidopeptide leukotrienes have been proposed as mediators of hypoxic pulmonary vasoconstriction. We studied the effects of nordihydroguaiuretic acid (NDGA), a lipoxygenase inhibitor, on hypoxic pulmonary vasoconstriction and on immunoreactive leukotriene C4 (i-LTC4) levels in lung lymph, perfusate and bronchoalveolar lavage (BAL) fluid in isolated, indomethacin treated, sheep lungs perfused with blood at a constant flow of 100 ml/kg/min. The protocol consisted of two randomized periods with inspired 02 concentration either 28.

Pneumocystis carinii pleural effusion. Pathogenesis and pleural fluid analysis.

We present three new cases of Pneumocystis carinii in pleural effusions of patients with AIDS, bringing the total number of reported cases to six. In our patients, diagnosis was made by visualization of Pneumocystis in pleural fluid stained with Gomori methenamine silver. LDH was greater than 400, and pleural fluid to serum LDH ratio was greater than 1.

Ventilator autocycling due to an endotracheal tube cuff leak.

Ventilator autocycling can occur with any ventilator if the sensitivity is improperly set or if a gas leak exists in the respiratory system which creates a negative change in proximal airway pressure. We report a case of ventilator autocycling in a paralyzed patient secondary to an endotracheal cuff leak which was misconstrued as assisted ventilation. We believe this is the first report of autocycling due to a cuff leak.

Effects of hypoxia on leukotriene activity and vasomotor tone in isolated sheep lungs.

To determine whether hypoxic pulmonary vasoconstriction was associated with release of sulfidopeptide leukotrienes (SPLTs) from the lung, we measured SPLT activity by bioassay (guinea pig ileum) and radioimmunoassay in lymph, perfusate, and bronchoalveolar lavage (BAL) fluid from sheep lungs (n = 20) isolated and perfused in situ with a constant flow of autologous blood (100 ml.kg-1.min-1) containing indomethacin (60 micrograms/ml).

Interaction of fatigue and hypercapnia in the canine diaphragm.

We studied 10 open-chest dogs and measured the pressure across the diaphragm (Pdi) in each period of the protocol during stimulation at frequencies of 1, 20, 50, and 80 Hz. Three ranges of arterial PCO2 (PaCO2) were examined: less than or equal to 26, 36-50, and greater than or equal to 89 Torr. The diaphragm was fatigued with repetitive phrenic stimulation (30 Hz).

Arterial CO2 partial pressure affects diaphragmatic function.

The purpose of this study was to examine in an in vivo preparation acute variations of PCO2 on diaphragmatic contractility. Plaster casts were snugly fit around the abdomen of six open-chested dogs, moving the abdominal contents rostrally. Diaphragmatic contractions against this very fixed load in response to phrenic nerve stimulation (supramaximal voltage at 1, 20, 50, and 80 Hz) or during spontaneous inspiratory efforts were virtually isometric (quasi-isometric).

Effect of carbon dioxide on diaphragmatic function in human beings.

We studied the effects of acute changes in the partial pressure of arterial carbon dioxide on diaphragmatic contractility and performance in four normal men. To study contractility we measured the ability of the diaphragm to generate pressure at a given level of excitation by determining the relation between the electrical activity of the diaphragm and transdiaphragmatic pressure during a voluntary quasi-isometric inspiratory effort carried out at different levels of end-tidal carbon dioxide. Our results show that contractility was reduced with hypercapnia (when end-tidal carbon dioxide was 7.