HYPERTENSION Flashcards
HTN parameters
> 140/90 x2 separate visits
prehypertension is 120-139/80-89
essential/primary HTN vs. secondary HTN
& causes
essential = >95% of cases, cause cannot be identified
- SNS overactivity 2/2 stress
- overproduction of Na+ retaining hormones & vasoconstrictors
- high Na+ intake + other dietary abnormalities
- increased renin secretion
- deficiencies of endogenous vasodilators
secondary = <5% of cases, identifiable cause (MANY)
- renovascular disease/renal parenchymal disease
- hyperaldosteronism
- aortic coarctation
- Cushing’s
- pheo
- pregnancy induced
pathophysiology of the effects of HTN
HTN –> increased myocardial wall tension
- ->
1. LV hypertrophy & HF
2. increased myocardial O2 demand, coronary insufficiency & HF
–> infarction
definition: hypertensive crisis
BP >180/120
emergency = acute or ongoing target organ damage
urgency = severe BP elevation w/out s/s target organ damage
preop evaluation of pts w/ essential HTN
- determine adequacy of BP control
- antihypertensive drug therapy (most should be continued throughout periop period)
- evaluate for evidence of end-organ damage
plan for maintenance of anesthesia
GOAL: adjust depth of anesthesia to minimize wide shifts in hemodynamics
- anticipate exaggerated BP responses to anesthetic drugs
- attempt to minimize wide fluctuations in BP
- administer balanced technique to blunt hypertensive responses (choose IA w/ low BG coefficient)
- consider invasive monitoring devices
- monitor for myocardial ischemia
- have drugs available to tx HTN/hypotension
which antihypertensive should be d/c-ed preop & why
ACEI/ARB (24-48hrs preoperatively)
- decreased venous return
- blunting of RAAS
treating intraoperative HTN/hypotension in pts w/ HTN
hypertension
- volatiles are a good choice
- tx pain (usually HTN d/t px)
- others: BB, nitro, nipride
hypotension
- decrease anesthetic depth
- increasing fluid gtt rates
- sympathomimetics if necessary (ephedrine, phenylephrine)
pulmonary artery HTN definition
> 25/10
s/s pulmonary artery HTN
- breathlessness
- weakness
- fatigue
- abdominal distention
why are pts w/ pulmonary HTN at an increased risk of hypoxemia?
- high R heart pressures predispose to a R-to-L shunt w/ patent foramen ovale
- fixed CO exists; increased O2 extraction w/ exertion = hypoxemia
- V/Q mismatch can result in perfusion of poorly ventilated alveoli
anesthetic management of pulmonary HTN
high risk of RVF
- continue meds throughout periop period
- avoid hypoxia, hypercarbia, acidosis (will increase PVR)
- maintain NSR (need R sided atrial kick)
- CVP is recommended
- have a pulmonary vasodilator available (milrinone, nitroglycerin, NO, prostacyclin)
considerations for patients on chronic BB therapy
- rebound SNS stimulation if therapy not maintained
- avoid BB in asthmatics/COPD/CHF/HB/SSS
considerations for patients on chronic methyldopa therapy
- rebound HTN w/ cessation of therapy
- decreased anesthetic requirements
considerations for patients on chronic clonidine therapy
- rebound HTN w/ cessation of therapy
- decreased anesthetic requirements
