Antihypertensives

Question 1

What is hypertension?

Answer 1

• Blood pressure has been classified into 4 categories in the JNC VII report
• normotension <120 and <80 mmHg
• pre-hypertension 120-139 or 80-89 mmHg
• stage I hypertension 140-159 or 90-99 mmHg
• stage II hypertension >160 or >100 mmHg
• must be more than 1 BP

Question 2

Pre-operative hypertension?

Answer 2

• Should cases be cancelled because of raised BP? american college of cardiology/american heart do not provide recommendations for when patients should be canceled or how long patient should be treated before surgery
• -“uncontrolled systemic HTN” is a low risk factor for complications
• -data suggest that diastolic blood pressure of >110 mmHg is a preoperative marker of preoperative cardiac complications in patients with chronic hypertension

Question 3

Intra-Op Hypertension

Answer 3

-hypertension is often transient in anesthesia due to surgical stimulation, intubation
Why do we care?
-increased risk for bleeding, CV events and MI

Question 4

Treatment of Acute HTN

Answer 4

-initial approach is prevention
-post operative HTN can result due to withdrawl of long term anti hypertension meds (exception may be ACEs and ARBs)
-try to find a cause
-treat DBP > 110, SBP > 200
Goal is to decrease BP by no more than 25%, brain and kidneys are prone to hypo perfusion if BP is lowered too rapidly
-make sure patient is not hypovolemic to maintain organ perfusion as you lower BP

Question 5

Pharmacotherapy

Answer 5

• Treat cause first: narcotics useful for decreasing stress response form pain, deepening anesthetic agents, relieve surgical stimulation (tourniquet pain)
• ideal agent is rapid acting and easily titrated (hypertension is usually transient)

Question 6

Pheochromocytoma

Answer 6

-rare catecholamine secreting tumor arising commonly from adrenal medulla and to some extent from other ganglia of the sympathetic chain, but can arise from any part of the body with an incidence of 1.55-2.1 per million populations per year

Question 7

Pheochromocymtoma

Answer 7

• induction of anesthesia, laryngoscopy, intubation, and peri-operative stress during tumor manipulation can lead to hazardous situation due to adrenergic crisis
• anesthetic goals: adequate control of BP, adequate control of HR and arrhythmias, restoration of normal blood volume

Question 8

Beta Blockers

Answer 8

-exact mechanism is not clear-decreased CO, that is not compensated for by baroreceptors
side effects: negative inotrope (can cause LV failure when given in large doses to those w/ LV dysfunction).
-non selective beta blockers can cause bronchospasm in those w/ asthma or COPD
-can potentiate the effects of insulin and oral hypoglycemia drugs

Question 9

Nitroprusside

Answer 9

• MOA: direct vasodilator, generates nitric oxide which activates guanylyl cyclase, increase in cGMP, effects on veins and arteries to reduce preload and after load
  use: to produce hypotension in surgery and hypertensive emergencies
• adverse/toxic effects: rapid decrease in MAP, cyanide accumulation ( infusion > 48 hours and/or impaired renal function)

Question 10

Nitroglycerin

Answer 10

MOA: generates nitric oxide which activates guanylyl cyclase, increase in cGMP

• reduces preload, oxygen demand, coronary vasodilator which increases collateral flow
• treatment of intraoperative MI (SL or IV)
  pharmacokinetics: short duration of action, tachyphylaxis
• • No reflex tachycardia

Question 11

Hydralazine

Answer 11

MOA: unclear, requires presence of NO, preferential effect on arterioles vs arteries and veins. Decreased peripheral vascular resistance, MAP, reflex increase in HR, contractility, Co
-usually used if beta blockers are unsuccessful
-reflex tachycardia
-start w/ small doses
-IM:IV (adults) hypertension: 2.5-40 mg
repeated if needed. Eclampsia- 5 mg q 15-20 min. If no response after a total of 20 mg, consider another agent