Anesthesia Flashcards
Allergic rxns are more common with (ester / amide) anesthetics
ESTER
Sxs of allergic rxn to local anesthetic
dermatologic manifestations to anaphylaxis
How common is a true allergic rxn to local anesthetic?
unlikely w/ preservative-free lidocaine
intraneural injection of anesthetic:
sxs
pain, paresthesias, subsequent local damage to nerve
intravascular injection of local anesthetic:
sxs
- (lower doses) circumoral numbness, lightheadedness, tinnitus
- (higher doses) seizures, coma, respiratory arrest
mortality of ASA Class III,
mortality of ASA Class IV
4% mortality in class 3
25% mortality in class 4
pulseless electrical activity
any organized rhythm w/o a palpable pulse; most common rhythm after defibrillation
how is pulseless electrical activity (PEA) treated?
administer epinephrine in 1 mg doses IV every 3-5 minutes
- treated like asystole
- NOT a shockable rhythm bc electrical system in heart is working properly
- do NOT use atropine
stress-induced adrenal insufficiency:
effects
hypotension or cardiac arrest
stress-induced adrenal insufficiency:
cause
- chronic steroid use
- trauma patients w/ adrenal hemorrhage
- septic patients w/ adrenal infarcts
stress-induced adrenal insufficiency:
TREATMENT
IV bolus of hydrocortisone 100 mg or dexamethasone 4 mg is administered if adrenal shock is suspected, esp if pt is not responding to initial resuscitation efforts →
if therapeutic dose of glucocorticoid is not administered, patient may die
calcium sulfate:
use and characteristics
- vehicle for local Abx delivery
- not even a fraction of exothermic rxn as PMMA
- peak @ 3 hours, elutes over 72 hours
- *ABX MUST BE IN POWDER FORM
main mechanism of local anesthetics
block voltage-gated sodium channels on the neuronal cell membrane
which nerve fibers are most sensitive to local anesthetics?
Type B fibers (sympathetic tone)
nerve fibers, by most sensitive → least to local anesthetics
- Type B (sympathetic tone) - most sensitive
- Type C (pain)
- Type A delta (temp)
- Type A gamma (proprioception)
- Type A beta (sensory touch & pressure)
- Type A alpha (motor)
why are Type B fibers more sensitive to local anesthetics than Type C?
Type B fibers are myelinated, so they are more sensitive even though than are thicker than the thin, unmyelinated C fiber
propofol:
systemic effects
- dose-dependent respiratory depression
- systemic reduction in blood pressure
- anticonvulsant properties
propofol:
mechanisms
- direct effect on myocardium
- direct on vascular smooth muscle
- decrease in sympathetic activity
(decreased vascular resistance in arterial and venous smooth muscle)
spinal anesthesia:
relative contraindications
- anti-coagulation
- sepsis
- local cellulitis
- hypovolemia or shock
- increased intracranial pressure
- MI < 6 months prior to surgery
what type of hemostasis is recommended in an actively bleeding post-op patient?>
mechanical hemostasis (e.g. intermittent pneumatic compression);
pharmacologic chemoprophylaxis is CONTRAINDICATED in actively bleeding patients
abx that can be mixed with PMMA
tobramycin
erythromycin
vancomycin
cephalosporins
why would LA block be delayed or fail on severely infected paronychia?
ST in area of infection are ACIDIC → fractionates the drug largely to its cationic form, creating a marked decrease in transport across the cellular membrane
all local anesthetics are:
[acids / bases]
weak bases; two forms
- lipid-soluble uncharged
- hydrophilic charged
how does pKa of LA affect use?
closer the pKa of the LA is to the pH of the soft tissues, the more e_fficient, effective, and quicker_ the block will be
why is it important to clarify duration of
prior corticosteroid therapy
any pt receiving equivalent of 20 mg/dL of prednisone for 5+ days is at risk of suppression of hypothalamic pituitary axis
how long does risk of HPA suppression last after 1 month of corticosteroid therapy?
6-12 months
if patient is at risk of HPA suppression, what should you do the day of surgery
Administer 50-75 mg of hydrocortisone the day of surgery, for a moderate stress procedure such as bunion
types of post-op fluid management
maintenance and replacement;
both are based on temperature (febrile), diet, and activity level
malignant hyperthermia:
symptoms
increased CPK, high fever, muscle rigidity, and EKG changes;
can be life-threatening
effects on adjacent digits after
digital amputation
one digit amputation → tendon imbalance in adjacent digits → contracture
this is a concern bc this contracture causes retrograde pressure and new ulceration can develop under adjacent met head
coumadin:
how many days to dc in advance
dc 3-5 days prior to sx
appropriate INR for surgery in patients
NOT on coumadin
~1
single most important prognostic factor for surgical outcomes
(specifically for smokers)
smoking cessation
perioperative cardiopulmonary arrest
sxs and tx
IMMEDIATE INITIATION OF ADVANCED CARDIOPULMONARY LIFE SUPPORT AND CALLING OF INTRAOPERATIVE CODE
- asystole
- nonpalpable carotid pulse
- no pulse oximetry plethysmography
symptoms of true opiate allergy
- sxs:
- hives
- maculopapular rash
- erythema multiforme
- pustular rash
- severe hypotension
- bronchospasm
- angioedema
- rare and seems to be IgE-mediated or T-cell mediated
hyperlipidemia drug that can cause rhabdomyolysis
statin medications (HMG-CoA Reductase Inhibitors)
- rare cases → assoc w/ severe myotoxicity that can result in rhabdomyolysis
- risk is increased when taking other medication that interact w/ cytochrome P3A4 (increases levels of statins)
- more often assoc w/ mild musculoskeletal sxs and myalgia
