Class 4 Deck 2 Flashcards
What does NTG do to non cardiac vasculature?
- Dilates meningeal vessels (Cautious w/ ↑ ICP)
- Decrease renal blood flow
- Dilates pulmonary vessels (↓ PVR)
What are the indication for NTG?
- Ventricular failure
- HTN
- Ischemic heart disease
How is NTG used in OB?
-To help relax the uterus
NTG adverse effects
- Postural HTN
- Tachy
- Headache
- Dizzy
- Weakness
- Methemoglobin
What patients need to avoid NTG?
- PDE5 inhibitors (Viagra)
- Glaucoma
- Head injury
- Anemia
- Hypotension
What are the advantages of NTG
- Rapid onset / Short duration
- Coronary vasodilator
- ↓ myocardial O2 consumption
- no toxicity / no steal
- ↓ PVR
What is hydralazine?
-Direct acting vascular smooth muscle dilator. (interferes with calcium ion transport)
What does hydralazine increase?
- CO
- HR
- SV
- Sympathetic output (baroreceptor reflex)
- contractility
- Renin
What does hydralazine decrease?
- SVR
- diastolic BP more than systolic
Hydralazine has a greater effects on _______ than _____?
Arterioles / Veins
What are the advantages of hydralazine
- Maintains cerebral blood flow
- Increases CO and SV
What are the disadvantages of hydralazine?
- Reflex tach
- reduced response to ephedrine
- sodium and water retention
- longer duration of action
- Increase myocardial O2 demands
What type of patients should hydralizine be avoided?
- CAD
- ↑ ICP
- Lupus
What are the side effects of hydralazine?
- Sodium and water retention
- Vertigo, Nausea, diaphoresis
What is the drawback of hydralizine in anesthesia?
-Long onset time
Name 3 alpha antagonists
- Phentolamine
- Phenoxybenzamine
- Prozosin
How does phentolamine work?
- Alpha adrenergic blocker
- Direct acting vasodilator
- Greater arterial than venous
What does phentolamine do?
- ↓ afterload and preload
- Promote EF and CO
- Decrease PVR
When is phentolamine used
- HTN from pheochromacytoma
- Clonidine withdrawl
- ED
- Extravisation of catecholamines
- improves asthma symptoms
What is phenoxybenzamine? what does is bind to?
- Prototype alpha 1 antagonist
- irreversibly binds to receptor
When is phenoxybenzamine used?
- Long term treatment of pheochromacytoma
- Ischemic PVD
- BPH
phenoxybenzamine can cause what effects?
- ↓ PVR to ↓ BP
- ↑ in NorEpi
- Crosses BBB
What is prazosin? What does it do?
- Oral selective alpha 1 antagonist
- Peripheral vasodilator (arteries more than veins)
- ↑ HR
- Improves urinary flow
Clonidine is what type of drug?
Alpha 2 agonist (decreases release of sympathetic neurotransmitters)
What are the uses for alpha 2 agonists (clonidine)
- Sedation
- Anesthesia sparing effect
- Peripheral nerve block
- Analgesia (postop, labor, chronic)
- Post op shivering
- Drug withdrawl
How does clonidine effect anesthesia?
- Reduce need for propofol and thiopental
- Alternative to N2O for shortening induction time
- Decrease adrenergic response to intubation
- Supplement regional blocks
What are the actions of clonidine?
- Decrease HR,BP, CO, SVR
- Baroreceptors reflex preserved (no orthostatic hypotension)
What happens if clonidine is stopped abruptly? How quickly can it be seen?
- Rebound HTN
- can happen after 6 days on med
How does alpha-Methyldopa work?
-In CNS it is metabolized to alpha-methylepinepherine which acts on alpha 2 receptors to decrease sympathetic outflow
When is alpha-Methyldopa used?
-Treat HTN during pregnancy, usually 3rd trimester
What is Dexmedetomidine (Precedex) do?
- Alpha 2 agonist for IV sedation (<24hr) in the ICU
- Maintain respiratory stability
- Light analgesia, no amnestic effects
- Pts are arousable (sleep like state) safer for non-anesthesia personal
What 3 drugs can reduce post op shivering?
- Demerol
- Clonidine
- Precedex
When is precedex used?
- Procedural sedation (Fiber optic intubation, regional anesthesia)
- Children who failed sedation by other techniques
Precedex must be used with caution in what patients and why?
- Heart Block (brady)
- Ventricular dysfunction (sinus arrest)
ACE inhibitors are recommended for what types of patients?
- Those that cant take beta blockers
- Bronchospasms
- DM (beta blockers decrease insulin)
When are ACE inhibitors used?
- Treat CHF and MR by afterload reduction
- Increase CO w/o decrease in preload
Why are ACE inhibitors not used in anesthesia?
-Risk of acute renal failure
How does and ACE inhibitor affect renal function of a hypertensive patient? Normotensive?
- Hypertensive = improves RBF and GFR
- Normo = renal function may decrease
Advantages of ACE inhibitors
- Minimal side effects
- No problems with abrupt withdrawl
Most serious side effects with ACE inhibitors
-Angio edema
ACE are not for use in what patients?
- Renal patients
- Pregnant
Why choose and ARB over an ACE inhibitor?
- Same hemodynamic effects
- Less cough and angioedema
- Can combine with diuretic / CCB
What is fenoldopam? When is it used?
- DA1 agonist
- Short term management of severe HTN
- Preserve RBF
Problems with fenoldpam?
- Tachycardia
- Hypokalemia
- Not renal protective
- expensive
