Hypertension Flashcards
Hypertension BP
130/80
Elderly show _________ with HTN
widened pulse pressure
Systolic rises more than diastolic (which can lower) as arterial compliance declines and sympathetic activity increases
High pulse pressure
Emerging as an important indicator for heart disease
Fore every 10 mm Hg increase, CV complications increase by 20%
MAP
average of BP over a single cardiac cycle (one ECG complex)
(SBP + DBP + DBP)/3
Normal 70-100 mmHg
How does autoregulation change in hypertensive pt?
Right shift - therefore to maintain autoregulation is higher
Autoregulation of cerebral vasculature occurs when MAP is
60-160 mmHg in normotensive pt
Essential htn comes from . . .
SNS overactivity
RAAS dysregulation
Oxidative stress
How htn evolves
- Initially presents as increase in CO with no change in PVR
- Then CO falls and total PVR increases, causing the sustained HTN
- From ANS, we see dysregulation of the baroreceptor complex and chemoreflex pathways
- In the RAAS system (slower, intermediate control), there is an increase in renin, causing increased AT2 and aldosterone levels that contribute to HTN
RAAS pathway
Kidneys detect drop in BP
Juxtaglomerular cells produce renin and secrete it into the circulation
Plasma renin then carries out the conversion of angiotensinogen, released by the liver, to angiotensin I.
Angiotensin I is subsequently converted to angiotensin II by the angiotensin-converting enzyme (ACE) found on the surface of vascular endothelial cells - in the lungs.
Angiotensin II is a potent vasoconstrictive peptide that causes blood vessels to narrow, resulting in increased blood pressure.
Angiotensin II also stimulates the secretion of the hormone aldosterone from the adrenal cortex.
Aldosterone causes the renal tubules to increase the reabsorption of sodium and water into the blood, while at the same time causing the excretion of potassium (to maintain electrolyte balance). This increases the volume of extracellular fluid in the body, which also increases blood pressure.
What are the local regulators of vascular tone in the endothelium
NO
ANP
BNP
Oxidative stress causes dysregulation of these enzymes
Baroreceptors
Sense pressure in the aortic arch and carotid sinus
Carotids send afferent signals to the medulla via Herring’s nerve (CN IX). Aortic baroreceptors send info via CN X.
Continuous firing from these baroreceptors occurs as they stretch (correlating to increased pressure), which reflexively enhances vagal tone and inhibits vasoconstriction.
When pressure is low, baroreceptor stretch is less, and reduces vagal tone and stimulates epi and NE release.
All volatile agents suppress this reflex
What is the end result of htn?
remodeling of small and larger arteries
endothelial dysfunction
end organ damage
How does echo clue us in to early htn?
LVH - CO is increased
Resistant htn
pt is taking 3-4 antihypertensive drugs of different classes
Refractory htn
htn persists despite 5 or more drugs
Consider secondary cause
Weight loss and HTN
For every 10 kg weight loss, systolic pressures decreased by 6 mmHg and diastolic by 4.6 mmHg
Pheo treatment
removal of tumor and pharmacologic intervention of the catecholamines it secretes
Suspect if pre-op assessment reveals adrenal mass and pt is HTN
Diabetic pts
anti-hypertensives
ACEI/ARBS
Non-diabetic pts, non-black
anti-hypertensives
Thiazide
ACEI
ARBS
CCB
Non-diabetic pt, black
anti-hypertensives
Thiazide
CCB
Anesthetic goals in HTN pts
- Hemodynamic stability
- Prevent myocardial ischemia from tachycardia, HTN, hypotension
- Prevent cerebral hypo-perfusion
- Prevent cerebral hemorrhage
- Prevent renal insult
When to cancel surgery due to HTN
In general, don’t delay unless urgency or crisis
180/100 = urgency (shoot for 10% decrease)
Emergency - increase in creatine, EOD
HTN manifestation treatment
encephalopathy
Clevidipine, nipride, labetalol, nicardipine
HTN manifestation treatment
Aortic dissection
Clevidipine, nicardipine, esmolol, labetalol
HTN manifestation treatment
AKI
Clevidipine, nicardipine, labetalol
HTN manifestation treatment
Pheochromocytoma
Phentolamine, phenoxybenzamine, propranolol, labetalol
HTN manifestation treatment
Cocaine
Labetalol, dexmedetomidine, Clevidipine
Cuff size
Too small a cuff - too high BP
Too large a cuff - too low
Cuff should cover 2/3 distance from elbow to the shoulder
Intra-op HTN causes . . .
increased bleeding
increase risk of ischemia and cerebral events
Labile/wide swings in pressure
Most labile time
Induction - wide sings from induction agents to hypotension to hypertension during laryngoscopy
Induction agents
Esmolol
0.3-1.5 mg/kg
Induction agents
Lidocaine
1-1.5 mg/kg
Induction agents
Fentanyl
1-3 mcg/kg
Induction agents
Ketamine
Not DOC bc it causes sympathetic activation
Induction agents
Versed
2 mg
Can decrease BP in anxious pts
Cushing’s Triad
Increased ICP
HTN
Bradycardia
Irregular RR
Vasopressin
- 2-2 units
* more typically 1 unit
Phenylephrine
40-100 mcg
Epi
10 mcg
Ephedrine
5-10 mg
Tricks to avoid HTN during extubation
Propofol Lidocaine Precedex BB before emergence Deep extubation - 1.3 MAC of gas
