Treating heart failure -- adjusting preload

summary

Hypoxia in acute heart failure and severe dyspnea are fatal threats. Once this happens, grandfather should immediately sit down, drop his feet, put oxygen inhaler on his face, and then lie flat on the bed. He should immediately inject morphine, intravenous vasodilator, quickly diuretic and reduce pulmonary edema. I want to talk about the treatment of heart failure.

Treating heart failure -- adjusting preload

First: adjust the preload of patients with cardiac insufficiency, ventricular filling pressure (preload) can be high or low (decreased ventricular filling pressure can be seen in acute heart failure), should be adjusted to a suitable height. For patients with acute myocardial infarction, pulmonary capillary wedge pressure (equivalent to left ventricular end diastolic pressure, LVEDP) of 2-2.4kpa (15-18mmhg) is the most appropriate. Lower than this value means that the blood volume is insufficient and the stroke volume will decrease. When it exceeds this value (overload), the stroke volume will not increase, but will induce heart failure. Therefore, the quantity and speed of infusion should be carefully controlled when infusion is given to patients with myocardial infarction or other cardiac insufficiency.

Second: adjust the afterload. Under a certain preload, the change of afterload will affect the cardiac function. If the afterload increases suddenly, the stroke volume will decrease correspondingly, but then it will return to normal due to compensatory adaptation. When the posterior negative pressure decreased, the stroke volume increased. This phenomenon has been paid more attention recently, and has become the basis for the use of vasodilators in the treatment of heart failure. For example, when using vasodilators such as sodium nitroprusside, nitroglycerin and benzylazoline, the cardiac output increases with the decrease of arterial pressure and peripheral resistance (the decrease of afterload).

Third: when strengthening myocardial systolic heart failure, the ventricular work of stroke is lower than normal (the curve of cardiac function moves downward to the right) even if the vedp has not reached the critical level. The effect of digitalis cardiac stimulants is to strengthen the contractility of myocardium, so that the heart can perform greater stroke work under the same preload as before treatment, even if the cardiac function curve moves upward to the left (Fig. 12-4). Digitalis cardiotonics have a good effect on chronic heart failure, but the effect on acute heart failure caused by acute myocardial infarction is uncertain, because they have adverse side effects such as arrhythmia and increase of myocardial oxygen consumption.

matters needing attention

After the above treatment, the cardiac output of patients may meet the needs of organs and tissues, and the clinical symptoms of heart failure can disappear. However, if the cause of heart failure is not removed, heart failure can occur again under certain incentives. After repeated occurrence of heart failure, the treatment effect may not be ideal.