Hypertension

Blood pressure is the force of blood exerted on the vessel walls. Systolic pressure is the pressure during the contraction phase of the heart and is the top number of a blood pressure reading. Diastolic pressure is the pressure during the relaxation phase or filling phase of the heart and is the bottom number of a blood pressure reading. Factors that alter peripheral resistance, heart rate, and stroke volume affect the blood pressure. Hypertension is defined as a systolic blood pressure greater than or equal to 140 over 90 mm Hg. If the client has diabetes or kidney disease, a systolic blood pressure greater than 130 mm Hg systolic and a diastolic blood pressure of 80 mm Hg or higher is considered hypertension and should be treated. The autonomic nervous system and circulating blood volume control blood pressure. Blood pressure also directly relates to circulating hormones such as antidiuretic hormones.

Hypertension is classified as either primary or secondary. Primary or essential hypertension develops without apparent cause; secondary hypertension develops as the result of another illness or condition. Some examples of diseases that result in secondary hypertension are diabetes, peripheral vascular disease, renal disease, preeclampsia, coarctation of the aorta, adrenal tumors such as pheochromocytomas, brain tumors, encephalitis, and primary aldosteronism. This and other chapters of the book discuss these diseases. Obesity and smoking also affect blood pressure. Appropriate treatment of the contributing illness improves the symptoms associated with secondary hypertension.