[Pulmonary gas exchange during isovolaemic haemodilution (author's transl)]. / Pulmonaler Gasaustausch bei isovolämischer Hämodilution.

In experiments on 6 closed chest dogs the behaviour of pulmonary gas exchange during isovolaemic haemodilution with 6% dextran was studied. The dogs were ventilated artificially using an inspiratory gas mixture containing 25% O2. A slight increase of arterial Po2 values was found. This change was accompanied by a decrease in alveolar-arterial Po2 and Pco2 gradients. The size of effective pulmonary capillary blood flow varied in accordance with the size of cardiac output. The changes of pulmonary O2 diffusing capacity could be explained by the effect of haemodilution per se.

[Haemodynamics and tolerance to hypoxia of the myocardium under 6%-oxygen ventilation following acute isovolaemic haemodilution in experimental animals (author's transl)]. / Hämodynamisches Verhalten und Hypoxietoleranz des Myokards unter 6%-Sauerstoffmangelbeatmung nach akuter isovolämischer Hämodilution in Tierexperiment

1. In experiments on closed chest dogs in a control group and a group of previous isovolaemic haemodiluted dogs a cardiovascular stress was produced by means of reduction of inspiratory O2 content to 6% O2--2. Under haemodilution only small changes of the heart rate, aortic pressure and dp/dtmax occurred, pointing to a decreased sympathoadrenergic response. Augmentation of LVEDP and pulmonary artery pressure is considered to be related to left ventricular insufficiency.--3. According to haemodynamic changes myocardial O2 demand in the control group during hypoxia is increasedby 120% and in contrast remains unchanged after previous haemodilution.--4. Despite the reduced oxygen content under haemodilution severe arterial hypoxemia affects mean survival time of the animals (18.5 min and 21.5 min respectively) only little. However, there is a greater variation from 11 to 26 min in the haemodiluted animals.

[Haemodynamics, oxygen demand and oxygen uptake of the heart during isovolaemic haemodilution (author's transl)]. / Hämodynamik, Sauerstoffbedarf und Sauerstoffversorgung des Herzens unter isovolämischer Hämodilution

1. In experiments on 5 closed chest dogs an isovolaemic haemodilution with 6% dextran resulted in a drop of haemoglobin content to 6,4g%. Except for a small decrease of arterial pO2 and O2-saturation the body oxygen supply remained undisturbed. -- 2. According to only very small haemodynamic alterations (except compensatory cardiac output increase) myocardial O2-demand increased very little and mainly is caused by moderate augmentation of ventricular wall tension. The decrease of arterial O2 content was fully compensated by an increase of myocardial blood flow. O2 supply to the myocardium was not critically changed. -- 3. In accordance with other investigators it is concluded that in case of coronary insufficiency or increased myocardial O2 demand intentional hemodilution should be avoided. Patients with myocardial insufficiency considered for therapeutic hemodilution should be digitalized preoperatively.

[Improvement of myocardial blood flow and cardiac hemodynamic by means of intraaortic balloon pumping IABP during experimental heart failure (author's transl)]. / Verbesserung der Koronardurchblutung und Kreislaufstabilisierung durch intraaortale Ballongegenpulsation IABP nach experimenteller Herzschädigung

The influence of the intraaortic balloon pumping (IABP) on the hemodynamic and coronary blood flow under control conditions and after experimental heart failure induced by coronary artery ligature was proved on eight dogs. By timely use of IABP (systolic pressure over 60-70 mmHg), the cardiac hemodynamics can be improved by means of reducing myocardial oxygen demands, and on the other hand by raising the coronary perfusion and oxygen supply.