Hypertension Listen to Audio Epidemiology Pathophysiology Longterm Treatment Preoperative Considerations Intraoperative Management Postoperative Management Epidemiology -leading cause of death and disease in the western society -overall prevalance is about 20-25% pathophysiology -long standing uncontrolled hypertension can accerlerate atherosclerosis -chronic increased afterload may lead to concentric LVH and diastolic dysfunction Possible mechanisms: -vascular hypertrophy -hyperinsulinemia -abnormal increases in calcium concentration possibly from impaired renal excretion -increased sodium concentration within the vascular smooth muscle -increased arterial tone -increased sympathetic tone -increased renin-angiotensin-aldosterone system (RAAS) Complications -CNS : cerebrovascular accident (CVA "stroke") -CVS : myocardial infraction, heart failure -Renal: renal failure -vasc : peripheral vascular disease long-term treatment Goal: decrease the progression of hypertension hence decreased complications (ex. CVA,MI,) Drug therapy -Beta Blockers -Ace inhibitors -Calcium channel blockers -Diuretics preoperative Considerations History -severity and duration of hypertension -current drug therapy -presence of complications -myocardial ischemia -ventricular failure -impaired cerebral perfusion -peripheral vascular disease Signs/symptoms -chest pain -exercise intolerance -shortness of breathe -nocturnal dyspnea -dependant edema -postural light headedness -syncope -amarosis and claudication Physical examination -vitals orthostatic hypotension implies -volume depletion -excessive vasodilation -sympatholytic drug therapy Ophthalmoscopic exam visual changes in retinal vasculature usually parallels the severity and progression of athersclerotic and hypertensive damange within other organs -carotid bruits -s4 gallop may be present in patients with LVH -s3 gallop usually late finding in patients with CHF -pulmonay rales usually late finding in patients with CHF Electrocardiogram -possible finding with longstanding hypertension -evidence of ischemia -conduction abnormailies -old infarcation -LVH -LV strain Chest x-ray -normal chest xray does not exclude LVH -boot shaped heart in LVH -cardiomegaly -pulmonary vascular congestion Echocardiogram -more sensitive in diagnosing LVH than other modalities -evaluates ventricular systolic function and ventricular diastolic function Labratory -chemistry to rule out other causes of hypertension (ex.conns syndrome) -evaulation of renal function intraoperative management OBJECTIVE: maintain stable blood pressure within 10-20% of preoperative levels if marked hypertension (> 180/120) then maintain high level range (140-150/80-90) MONITORING: most patients do not require special intraoperative monitoring -arterial line patients with wide swings in blood pressure surgical procedures associated with a rapid or marked changes in cardiac preload or cardiac afterload -ecg monitor signs of ischemia -urine output patients with renal impairment undergoing surgery greater than 2 hours pulm art cath patients with hypertension may have reduced ventricular compliance secondary to LVH therefore higher PAOP are generally needed (12-18) to maintain adequate LVEDV and CO INDUCTION induction and intubation often are associated with periods of hemodynamic instability -hypotensive response of induction and hypertensive response of intubation creates hemodynamic instability Hemodynamic instability: -induction: anesthetic agents tend to be cardiodepressant +/- vasodilation Hypotensive response antihypertensive agents tend to be cardiodepressant +/- vasodilation -intubation: direct laryngoscopy Hypertensive response ETT intubation Treatment of hypotensive response -small doses of phenylephrine (25-50 ug) -small doses of ephedrine (5-10 mg) if increased vagal tone Treatment of hypertensive response to intubation -deepening anesthesia before intubation -short brief intubation ( duration has some correlation to the degree ofexaggeration hypertensive response) Intravenous anesthetics generally safe for induction for hypertensive patients -benzodiapines -barbituates -propofol -etomidate induction should be performed under deep anesthesia yet avoiding hypotension Several techniques for deep anesthesia induction include: -volatile anesthetis for approx 5-10 mins -bolus of opiod ( ex. 2.5 - 5 ug/kg) -administering lidocaine (ex. 1.5mg/kg ) -beta blockade -i.v Nitroglycerin -topical anesthesia -ketamine contraindicated because it may stimulate the sympathetic nervous system increased sympathetic nervous stimulation may increase MAP MAINTENENCE -volatile anesthetics +/- N20 -balanced anesthetia: (volatile anesthetics +/- N20 + opiods + muscle relaxants) -t.i.v.a. volatile anesthetics vasodilate and allow for rapid and reversible titration of MAP sufentanil may provide the greatest autonomic supression and control of blood pressure Intraoperative hypertension -exclude reversible causes ex. inadequate anesthetic depth hypoxemia hypercarbia Hypotensive agent depends on: severity, acuteness and cause of hypertension baseline ventricular function heart rate +/- bronchospastic pulmonary disease Treatment of intraoperative hypertension -beta blockers: patients with good ventricular function accelerated heart rate avoid in patients with bronchospastic disease options: - beta1 selective (ex. esmolol) - beta nonselective (ex. propanolol) mixed alpha/beta blockers able to decrease blood pressure without reflex tachycardia avoid in patients with bronchospastic disease ex. labetolol calcium channel blockers nicardipine: useful in patients with bronchospastic disease nimodipine: may be associated with reflex tachycardia reflex tachycardia may be associated with myocardial ischemia vasodilators nitroprusside: most rapid and effective in treatment in moderate-severe hypertension nitroglycerin : less effective than NTP but useful in treating myocardial ischemia hydralazaine: delayed onset but provides sustained blood pressure control associated with reflex tachycardia POSTOPERATIVE MANAGEMENT -hypertension should be anticipated in patients with poorly controlled hypertension -sustained increase in blood pressure may be contribute to: -myocardial ischemia -heart failure -formation of wound hematoma -dissruption of vascular suture line -correctable contributing factors to hypertension: -respiratory abnormalities -volume overload -bladder distension -pain once reveresible causes have been ruled out then drug therapy may be the next step