Parameters Of Pulmonary Circulation Research Articles

Effect of bronchospasm on hypoxic pulmonary vasoconstriction (HPV) in perfused cat lungs

It has been believed that autonomic nerve plays little role in HPV. However, these studies were done in the conditions with normal bronchial tone. Little has been known about the role of autonomic nerve on HPV during broncho-spasm as in the case with bronchial asthma, in which autonomic nerves are involved in pathogenesis and the altered tone of autonomic nerve may affect pulmonary circulation. To clarify the role of autonomic nerves on HPV when there is bronchospasm, we induced hypoxia while provoking bronchospasm by intratracheal administration of histamine or acetylcholine in isolated cat lungs (n=36) perfused with diluted autologous blood (Ht=l 0%). We used 30% 02 and 5% CO2 for noormoxia and 2% 02 and 5% CO2 for hypoxia. Hexamethonium (C6) as a ganglion blockaer, tetrodotoxin (TTX) as a blockade of nerve conduction, atropine a muscarinic receptor antagonist, and also selective or non-selective adrenergic inhibitors (8: propranolol, 131 ;acebutolol, metoprolol, 13-2;butoxamine, alpha; phentolamine, alpha-1 ; prazosin, alpha-2; yohimbin) were administered before induction of bronchospasm following control HPV. C6 and TTX did not affect parameters of pulmonary circulation when HPV was not accompanied by bronchospasm or when bronchospasm was induced during normoxia. Nevertheless, these agents attenuated HPV when there was bronchospasm. Atropine almost completely abolished HPV during bronchospasm. Beta and selective 13-2 inhibitors also completely abolished HPV during bronchospasm. Alpha blockades did not affect HPV even when there was bronchospasm. We conclude that autonomic nerves, especially vagal nerves and 13 adrenergic nerve play a crucial role in HPV when it occured during bronchospasm. These finding may indicate that many sympathetic agonist and anti-cholinergic drugs, used in the treatment of bronchial asthma, may affect ventilation-perfusion matching.

Pulmonary vascular resistance variation over time in candidates for heart transplantation

Increased pulmonary vascular resistance (PVR) is an incremental factor for early death after heart transplantation. 1 Because PVR modifications are largely unpredictable in amount and rate, and the time spent by patients on the waiting list is often long, periodic reassessment of pulmonary hemodynamics is advisable. 2 To quantify PVR variation over time and identify the factors that determine such variation, we retrospectively analyzed the hemodynamic parameters of pulmonary circulation measured on 2 different occasions in a group of patients who were candidates for heart transplantation.

A nonlinear fluid model for pulmonary blood circulation

In this paper, we apply a quasi-one-dimensional unsteady nonlinear fluid model to study human pulmonary circulation. Eighteen generations of blood vessels composed of the branching arterial, capillary and venous distensible vessel segments make up the complete pulmonary circulation. The numerical result gives satisfactory agreement with the physiological experimental data: a dramatic pressure drop occurs in the arterioles and postcapillaries, a negative transmural pressure is shown in the postcapillary and small venous segments, a large reverse flow occurs in the main pulmonary artery during the diastolic period, and the reverse flow decreases gradually along the pulmonary tree. In the microgravity case where g = 180 cm s −2, the computation illustrated the effect of gravity force on the blood distribution in the different parts of the pulmonary circulation. The effect of gravity on the total output is not obvious. The effect of local factors which initiate the variations of the geometrical or mechanical parameters of pulmonary circulation can be simulated quantitatively by this model. The proposed model can be very useful for clinical practice and for studying the extreme cases which are very difficult to investigate by experiments.

A study on the pulmonary functions and the pulmonary circulation in cardio-pulmonary diseases. I. Pulmonary diffusing capacity in cardio-pulmonary diseases.

Pulmonary diffusing capacity (DLCO), alveolar membrane diffusing capacity (DMCO), and pulmonary capillary blood volume (VC) were determined with CO single breath method in (i) healthy subjects and, (ii) patients with cardiopulmonary diseases. In the latter right heart catheterization was also performed. Values obtained were compared between healthy subjects and patients with cardiopulmonary diseases. They were also compared with those reported by other workers. Relationships between DLCO, DMCO or VC and hemodynamic parameters of pulmonary circulation were examined.