By means of ultrasonic method used in acute experiments on cats with open chest under nembutal narcosis the authors studied the linear and volumetric blood flow velocity in the ascending aorta and conus of the pulmonary artery, the balance between the cardiac output of right and left ventricles, as well as blood pressure (BP) in pulmonary and femoral arteries, the pulmonary microvascular bed under conversion from traditional to the high frequency jet ventilation (HFJV). It was shown that under HFJV there were decreases in pulmonary BP and pulmonary vascular resistance, a reduction of right ventricular output, redistribution of blood to the general circulation. At the same time, in most experiments the linear blood velocity in the aorta and in the pulmonary artery, systemic BP, the general vessel resistance remained stable. HFJV, unlike conventional artificial lung ventilation did not cause any deformation of the pulmonary microvascular bed. There was an insignificant decrease of the capillary perfusion index. The change of such parameters as cardiac output, stroke volume, stroke index, cardiac in index in the central circulatory hemodynamics occurred 5 minutes following the same and unidirectional changes in the lesser circulation. The stabilisation of fundamental hemodynamic parameters took place from 10 to 20 minutes after conversion to HFJV.

Animals↗

PubMed1993

[Intravascular measurements of the blood flow in rats].

The blood flow velocity in aorta was measured in rats with intravascular probes. Ultrasonic probes was fixed at the end of polyethylene tubing 0.6 mm in diameter. Miniature piezoelectric crystal worked on 33 MHz frequency. Simultaneously cardiac output were measured with cuff probes placed on ascending aorta. Correlative coefficient between them was 0.96 in static experiments. Dynamics of cardiac output process was caused by injection of vasoactive agents and asphyxia. The difference between intravascular probes and cuff probes blood flow parameters were 6-9%, strike volume 4-6%, cardiac output 5-7%. In ten cases intravascular probes was implanted in ascending aorta for hemodynamics study on conscious rats.

Animals↗

PubMed1993

[The effect of high-frequency ventilation of the lungs on the pulmonary and systemic circulations in microembolism of the pulmonary artery].

The linear and volumetric blood flow velocity in the ascending aorta and pulmonary artery conus, right-left ventricular ejection balance, pulmonary and femoral arterial blood pressures, pulmonary microcirculation in fat pulmonary microembolism induced during the routine and high-frequency jet lung ventilation (HFJLV) were studied by ultrasonic techniques in acute experiments on cats with open chest under nembutal narcosis. Pulmonary microembolism was shown to resulted in 487 and 252% increases in pulmonary vascular resistance during the routine and HFJLVs, respectively. There were also 167 and 127% increases in mean pulmonary pressure and 60 and 34% decreases in the volumetric velocity of pulmonary blood flow. The linear velocity of pulmonary blood flow was unchanged with routine lung ventilation, whereas it decreased by 68% with HFJLV. Microembolism impaired the balance between right and left ventricular ejections with blood being redistributed into the greater circulation. The imbalance lasted 5-7 min during HFJLV, while with the routine lung ventilation it was preserved up to the end of the experiment, and systemic blood pressure and total peripheral vascular resistance decreased. Alveolar edema developed in interstitial pulmonary edema. The animals' death occurred 40-60 min later.

Animals↗

PubMed1993

[The effect of verapamil and nifedipine on the systemic hemodynamics and liver macro- and microcirculations in rats with acute massive blood loss].

Systemic hemodynamics and hepatic macro- and microcirculation (ultrasonic technique, biomicroscopy) were studied in intact rats and rats with acute massive hemorrhage after intravenous administration of the calcium antagonists verapamil and nifedipine. It was shown that verapamil deteriorated the posthemorrhagic period in rats with decompensated hemorrhage which was associated with the specific features of the calcium antagonist on the cardiovascular system of intact rats (decrease of blood pressure, total peripheral resistance, heart power). In rats with compensated hemorrhage verapamil and nifedipine blocked the development of posthemorrhagic liver microcirculatory disturbances, improved hepatic tissue perfusion and stabilized portal organ blood flow velocity on the longer period than in the untreated group of rats.

Acute Disease↗

PubMed1993

[Pulmonary blood circulation and respiration in hypoxic and circulatory hypoxia].

The linear and volumetric blood flow velocity in left low-lobar pulmonary artery and vein, the balance between cardiac output of right and left ventricles, as well as the blood pressure in pulmonary and femoral arteries, respiratory movements of the chest in hypoxic (3-5% O2 in nitrogen) and circulatory (acute hemorrhage) hypoxia were studied by ultrasonic method in acute experiments in cats under nembutal narcosis. It was shown that under the influence of severe hypoxic hypoxia the blood pressure in the pulmonary artery and the pulmonary vascular resistance increased; in the majority of the experiments, respiratory standstill without transitional stages occurred within 3 to 20 minutes. In circulatory hypoxia, the development of respiratory disorders was gradual with the appearance of pathological types of respiration such as apneusis and gasping occurring with a drop of systemic blood pressure to 30-40 mmHg, lowered pulmonary AP and 3-10-fold increased pulmonary vascular resistance. In hypoxic hypoxia the cardiac output changed insignificantly, without changes in the balance between cardiac output of the right and left ventricles. Only in the general circulation was observed. In circulatory hypoxia with decreased cardiac output redistribution of the blood to the general circulation occurred from the very beginning of the hemorrhage. Reinfusion of the autoblood restored the balance between the cardiac output of the right and left ventricles. The index of the capillary perfusion in the lungs decreased in parallel with a decrease of the pulmonary blood pressure. The index of capillary perfusion in hemorrhage decreased in parallel with a decrease of the pulmonary AP.

Acute Disease↗

PubMed1992

[ACTH inhibits the development of primary decompensation of the systemic and portal circulation in acute blood loss in rats].

Using the method of contact luminescent biomicroscopy of the liver and intestine coupled with the measurement of systemic blood pressure by micromanometer and ultrasonic registration of blood flow velocity in portal vein and hepatic artery it has been established that in rats with acute decompensatory hemorrhage fragments of ACTH (1-24) and (4-10) improve the state of portal macro- and microcirculation and increase the life span 2-3-fold. ACTH does not influence the dynamics of acute compensatory hemorrhage and the development of the posthemorrhagic microcirculatory disturbances (local microstases, microthromboses, erythrocyte aggregation).

Acute Disease↗

PubMed1992

[Phrenic blood flow in cats with closed abdominal cavity].

By means of ultrasonic method, used in acute experiments on cats with closed abdominal cavity under nembutal narcosis, the authors studied the linear and volumetric blood flow velocity in left phrenic artery, the resistance of vascular bed of the phrenic artery, systemic blood pressure, respiration excursions during asphyxia, hypoxia, infusion of some biologically active substances. It was shown, that shortening of the diaphragm has definite influence on the blood flow and resistance of the vascular bed of the phrenic artery; the degree of the decrease of the blood flow in inspiration (on relation to the value of the blood flow in expiration, that passed as 100%) does not differ significantly in quiet and intensive respiration. Under the influences, the resistance of vascular bed of the phrenic artery decreases, the linear and volumetric blood flow increases, that indicates large reserve of the vascular bed of the phrenic artery for the increase of the blood flow.

Abdomen↗