PREOPERATIVE EVALUATION OF HYPERTENSION

Although there are different medical conditions associated with the diagnosis of hypertension, this article focuses on relevant issues concerning the preoperative evaluation of patients with essential hypertension. In considering the preoperative evaluation of patients with hypertension, it is important to consider the prevalence of this medical condition. Hypertension is one of the most common indications for long-term treatment in the Western world because of the evidence that such treatment substantially reduces cardiovascular morbidity and mortality. About 20% of adults aged older than 40 have a blood pressure greater than 140/90 mm Hg, with a risk of stroke 100% higher than subjects of the same age with a blood pressure of 125/75 mm Hg. 73 The prevalence of hypertension in surgical subgroups, such as patients having an arteriovenous fistula placement for vascular dialysis access, may be disproportionately increased. The incidence of various risk factors in 469 patients studied at the Mayo Clinic were hypertension (92%), diabetes mellitus (26%), coronary artery disease (86%), and previous myocardial infarction (42%). 100 The incidence of hypertension in 83,958 Veterans Administration Medical Center patients was 36%. 65 Subgroups of essential hypertension may be considered as isolated systolic hypertension (ISH), isolated diastolic hypertension (IDH), or mixed hypertension. The prevalence of these hypertensive subgroups in elderly patients in an outpatient setting was ISH, 19.1% (systolic >160 mm Hg and diastolic <90 mm Hg); IDH, 5.7%; and mixed hypertension, 9.8%. 31