Top 7 Causes For High Blood Pressure In Hemodialysis Patients
It is reported that 70-90% of hemodialysis patients worldwide are accompanied by hypertension, which can not only aggravate the progress of chronic kidney disease, but also increase the incidence and mortality of cardiovascular disease. With the increase of the number of hemodialysis patients, hemodialysis hypertension, a common complication of MHD, has attracted more and more attention. Then, why do hemodialysis patients suffer from high blood pressure?
1. Increase in volume load
Most hemodialysis patients have partial or complete loss of glomerular function. Excessive intake of water and sodium or inadequate dialysis will lead to imbalance of water and sodium in the body, resulting in increased capacity load, increased cardiac output, increased peripheral vascular resistance, and eventually increased blood pressure. Studies have shown that the systolic blood pressure before dialysis increases by 1 mmHg for every 1% increase in body mass during dialysis, and the change of systolic blood pressure before and after dialysis also increases by 1.08 mmHg. Increased body mass during dialysis was associated with end-point events such as heart damage, congestive heart failure, aortic aneurysm, and stroke.
2. RAS activator
HD patients with renal ischemia and renal function impairment activates RAS, stimulates renin, and increases angiotensin Ⅱ secretion. Increased angiotensin II causes the contraction of vascular smooth muscle, stimulate sympathetic nervous system and promote nerve endings to release norepinephrine, which leads to increased vascular resistance and high blood pressure. Studies have found that 50% aldosterone is secreted by angiotensin Ⅱ stimulating the adrenal gland secretion. The increased secretion of aldosterone promotes the reabsorption of sodium in renal tubules, resulting in water and sodium retention and hypertension.
3. The activation of sympathetic nervous system
Patients with chronic renal failure often have abnormal autonomic nervous system function. Kidney ischemia activates the renal afferent nerve, leading to asymmetry dimethyl arginine and angiotensin Ⅱ vasoconstrictor secretion to increase. This can cause overactivation of sympathetic nervous system, reduced vascular compliance and elevated blood pressure in dialysis patients.
4. Blood vascular endothelial cells functional Disorder
Vascular endothelial cells can secrete nitric oxide, endothelin and other vasoactive substances.
Endothelin 1 (ET-1) is a vasoconstrictor, which causes vasoconstriction and vasofibrosis. Therefore, vascular endothelial cells play an important role in regulating vasodilation and systemic vascular resistance. ET-1 can lead to elevated blood pressure as well. Studies have shown that the et-1 level of HD patients with hypertension is higher than that of HD patients with normal blood pressure.
5. The use of EPO
Most hemodialysis patients suffer from renal anemia and need to inject recombinant human erythropoietin (EPO) to relieve anemia. While improving anemia, EPO may cause vasoconstriction, increased plasma viscosity, peripheral vascular resistance and vascular endothelial cell dysfunction, etc, all of which can lead to increased blood pressure.
6. Secondary hyperparathyroidism
Secondary hyperparathyroidism is another cause of high blood pressure in hemodialysis patients. Hemodialysis patients often suffer from hyperparathyroidism. The increased hyperparathyroidism results in increased intracellular calcium ion level and vascular smooth muscle contraction, and then increased blood pressure occurs.
7. The clearance function of hemodialysis to drugs
Blood purification will affect pharmacokinetics from drug clearance pathways, drug distribution volume, protein binding rate and other aspects. The properties of dialysis membrane/filter membrane and the molecular weight and charge of drugs will also affect the clearance function of hemodialysis to drugs. In the process of taking antihypertensive drugs to control hypertension in hemodialysis patients, whether antihypertensive drugs are cleared by hemodialysis is also one of the factors to be considered when choosing antihypertensive drugs.
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