Monday August 31, 2009
Hypertension management in perioperative period


Patients undergoing surgical procedures especially cardiac surgery can experience hypertensive urgencies (ie. severe blood pressure elevations without end organ dysfunction) or hypertensive emergencies (i.e. severe blood pressure elevations BP >180/110 mmHg with impending or progressive end organ damage), before, during, or after the procedure.


There are several continuous infusion options to control the hypertensive crisis:


Esmolol (ultra-short action cardioselective b blocker)

Preferred use: Acute myocardial ischemia, ideal choice when CO, HR, and BP are increased

Dose: LD 500-1000 microgram/kg over 1 minute; Infusion starting at 50 microgram/kg/min, titrating up to max 300 microgram/kg/min as needed to maintain BP

Rapid onset of 60 seconds, duration of action 10-20 minutes

Comment: Caution should be used in patient with COPD


Nicardipine (short-acting dihydropyridine CCB)

Preferred use: Acute myocardial ischemia, acute renal failure, acute ischemic stroke/intracerebral bleed, eclampsia/preeclampsia, hypertensive encephalopathy, sympathetic crisis/cocaine overdose

Dose: 5 mg/hr increasing by 2.5mg/hr every 5 minutes to maximum 15mg/hr until BP achieved. It has been seen that doses have been titrated up to 30-45 mg/hr.

Comment: Increases SV and coronary blood flow


Labetalol (a1 and non selective b1 ­blocker)

Preferred use: acute aortic dissection, acute myocardial ischemia, acute ischemic stroke/intracerebral bleed, eclampsia/preeclampsia hypertensive encephalopathy

Dose: May be given as bolus doses or continuous infusion, Bolus: LD 20mg IV, with incremental dose of 20-80mg every 10 minutes until BP achieved, Continuous IV: LD 20mg IV, infusion 1-2 mg/min titrated up until BP achieved, Max dose 300mg over 24 hours

Onset of action 2-5 minutes, duration of action 2-4 hours

Comment: Reduces SVR without reducing total peripheral blood flow. Caution should be taken in patients with HF. Avoid in patients with severe sinus bradycardia, heart block greater than 1st degree, and asthma.


Nitroglycerin (direct vasodilator or peripheral capacitance and resistance vessels)

Dose: 5 microgram/min every 5 minutes to 20 microgram/min. If not response at 20 microgram/min then increase by 10 microgram/min to max dose of 200 microgram/min, Onset of action 2-5 minutes, duration 10-20 minutes

Comments: Reduces BP by reducing preload and CO. Should not be used in patients with cerebral compromised or renal insufficiency



Sodium nitroprusside (arterial and venous vasodilator)

Preferred use: hypertensive emergency without cerebral compromise or renal/hepatic insufficiency

Dose: 0.5 microgram/kg/min titrated as tolerated, max 2 microgram/kg/min Onset of action is seconds, duration of action 1-2 minutes

Disadvantages: not recommended for patients who have decreased cerebral blood flow, accumulation of cyanide and thiocyanate

Comment: Duration of use should be limited to 72 hours due to the potential for toxicity



Reference:

Varon J. Vascular Health and Risk Management. 2008;4(3):615.
Varon J. Drugs. 2008;68(3):283