Adjuncts To Anesthesia Flashcards
Aspiration of ____ of volume at a pH of < _____ will be sufficient to produce aspiration pneumonia
25 ml; 2.5
Risk factors for aspiration
Full stomach, intestinal obstruction, hiatal hernia, obesity, pregnancy, reflux, emergency sx, & inadequate depth of anesthesia
How can you reduce risk of aspiration during induction?
RSI & sellick’s maneuver (cricoid pressure)
How do anesthetics increase the risk of aspiration?
Decrease LES tone, and decrease or obliterate gag reflex
What type of cells have the highest concentration of Histamine?
Basophils & mast cells
Effects of H1 activation on broncial smooth muscle and pulmonary beds
Bronchoconstriction and pulmonary vasodilation
Effects of H2 activation on broncial smooth muscle and pulmonary beds
Mild bronchodilation and histamine-mediated pulmonary vasoconstriction
H__ receptor activates phospholipase C, while H__ activates cAMP
1; 2
Increases capillary permeability & ventricular irritability.
Contraction of intestinal smooth muscle
Attracts leukocytes & induces synthesis of prostaglandin
H1 receptor
Increases HR & contractility
Increases gastric acid secretion
Suppresses T lymphocytes
H2 receptors
How do H1 & H2 affect peripharal & coronary arteries?
Dilation
Located on histamine-secreting cells & mediated negative feedback inhibiting synthesis & release of additional histamine
H3 receptor
Metabolizes histamine to inactive metabolites that are excreted in urine
Histamine-N-methyltransferase
Although ___ blockers prevent bronchoconstrictive response to histamine, they are ineffective in treating _____
H1; bronchial asthma
How do H1 blockers affect ventilatory drive?
Cause significant sedation, but ventilatory drive is unaffected in the absence of other sedatives
Why do newer (2nd generation) H1 blockers produce little or no sedation? (Loratidine, fexofenadine, cetirizine)
Limited penetration of BBB
Dose of diphenhydramine
25-50 mg (0.5 - 1.5 mg/kg) q 4-6 hrs
Which H2 antagonist can be given safely over 2 min w/o SE?
Famotidine
_____ decreases hepatic flow & binds p-450. Which H2 antagonists do not effect p-450?
Cimetidine; ranitidine (weak), Famotidine, nizatidine
Antacids _____ gastric pH and ________ intragastric volume
Raise, increase
Which is better for aspiration, particulates or nonparticulates?
Nonparticulates. Particulates are as bad as acid aspiration
Nonparticulates lose their effectiveness ______ after ingestion
30-60 min
Antacids slow rate of absorption for which drugs?
Digoxin, cimetidine, & ranitidine
Antacids quicken rate of elimination for what?
Phenobarbital
Dose and onset of regaln
10-20 mg (0.25mg/kg); 1-3 or 3-5 min onset
Reglans prokinetic action in upper GI is not dependent on _____ but is abolished by ______
Vagal innervation; anticholinergic agents
Action fo Reglan
Increases LES tone, speeds gastric emptying, & lowers gastric fluid volume (by enhancing stimulation of ACh).
Antiemtic effects by blocking dopamine receptors in CTZ
Which pts should reglan be avoided in?
Intestinal obstruciton, parkinsons, & pheochromocytoma (hypertensive crisis)
ALL serotonin receptors except ____ are coupled to G proteins & affect adenylate cyclase or phospholipase C. ____ are mediated via an ion channel
5-HT3
The 5-HT3 receptor mediates vomiting and is found where?
The GI tract & brain (area postrema)
Serotonin is a powerful vasoconstrictor of both arterioles & veins except where?
In heart & skeletal muscle (vasodilation)
_______ from released serotonin is a prominent feature of carcinoid syndrome
Bronchoconstriction
Activation of _____ causes platelet aggregation
5-HT2
Inhibit substance P at central & peripheral receptors. Can be used to reduce PONV as an additive with ondansetron
Neurokinin 1 antagonist. Aprepitant (Emend)
Depletes substance P and inhibits pain signal transmission in surgical wounds.
Capsaicin (TRPV1 receptor agonist)
Selective activation of ___ chemoreceptors by low doses of ____ stimulate hypoxic drive. What does this cause?
Carotid; Doxapram; produces increase in tidal colume and slight increase in RR
Large doses of doxapram stimulate what?
Central respiratory centers in the medulla
What type of opioids does Naloxone reverse?
Endogenous & exogenous
Low doses of _____ reverse the side effects of epidural opioids w/o necessarily reversing the analgesia
IV naloxone
The extent of sympathetic stimulation from abrupt reversal of opioid analgesia is = ?
The amt of opioid being reversed & speed of reversal
Histamine _____ arterial BP and _____ heart rate and myocardial contractility
Reduces; increases
