- Continuing Education
Blood pressure (BP), the lateral pressure exerted by blood in a unit area of the blood vessel wall, is a function of cardiac output and peripheral vascular resistance.1 When the blood volume exceeds the limited volume capacity of the vascular compartment because of volume expansion or increased vascular resistance the patient develops hypertension (HTN). BP is classified as normal (<120/80 mmHg), elevated (120‑129/<80 mmHg), stage 1 HTN (130‑139/80‑89 mmHg), or stage 2 HTN (≥140/90 mmHg).18
HTN is known as the “silent killer” because signs and symptoms, i.e., flushed face, restlessness, headache, dizziness, tinnitus, visual disturbances, dyspnea, and a hammering pulse are not observed until the systolic BP is ≥180 mmHg or the diastolic BP ≥110 mmHg; or until evidence of target organ damage manifests.19 Target organ damage may include renal insufficiency and end-stage renal disease; CAD, left ventricular hypertrophy, and HF; stroke; peripheral vascular disease; and hypertensive retinopathy.19
The treatment of HTN may include (1) diuretics to reduce blood volume, (2) ACE inhibitors or AT II receptor antagonists to modulate the RAAS, (3) β1-adrenoceptor antagonist, α1-adrenoceptor antagonists, and central α2-adrenoceptor agonists to reduce sympathetic tone, and (4) Ca2+ channel blockers and K+ channel activators to reduce vascular tone4-6,17 Frequently, two or more agents from different drug classes may be required to reach target BP in a particular patient.
BP >180/110 mmHg is a minor independent risk factor for a major adverse cardiac event (MACE) in association with dental procedures performed under local dental anesthesia.19 However, high BP is associated with an increased stroke risk and is a useful marker for the presence of significant CAD. HTN is associated with several diseases to include adrenal disorders, dyslipidemia, diabetes mellitus, obesity, renal disease, and thyroid disorders. Contributory behavioral factors include a sedentary lifestyle and exposure to alcohol and tobacco.18,19
Hypertensive urgency is characterized by a gradual elevation of BP in patients with chronic, slowly progressive end-organ damage.17 Clinically it may manifest as stroke or myocardial infarction (MI).17 Common signs of stroke include unilateral paralysis or numbness affecting the face or an extremity; vision loss; slurred speech; and / or confusion. Perioperatively, when a conscious patient experiences chest pain and the BP drops from baseline the diagnosis of MI should be considered. In contrast, when a conscious patient experiences chest pain and a rise in BP from baseline the diagnosis of acute angina pectoris is more likely.
Hypertensive emergency is a rare life-threatening condition characterized by severe, acute BP elevation associated with acute vascular injury.17 The vascular injury manifests clinically as retinal hemorrhage, papilledema, encephalopathy, acute renal insufficiency, and acute left ventricular (LV) failure. The treatment of patients with hypertensive emergency mandates rapid reduction of BP in a hospital setting to prevent irreversible end-organ damage.17
Signs and symptoms of hypotension, defined as BP <90/60 mmHg, include dizziness, and fainting (syncope); rapid, shallow breathing; fatigue, lack of concentration, and depression: cold, clammy, and pale skin; and thirst.19 Causes range from impaired homeostatic mechanisms of BP regulation as in old age, dehydration, and antihypertensive therapy.19