Flashcards in ACE 2012 9B Deck (106)
What is naltrexone used for and what is its mechanism of action?
Alcohol or opioid dependency and is a mu, kappa, and delta receptor competitive antagonist
What do you do preoperatively for a patient taking naltrexone for alcohol dependency?
Stop it because it will hinder with pain control when you give opioids intraop (do not need to taper)
How would your opioid management change in a patient who is taking ER morphine/naltrexone pill?
No change, the naltrexone is actually behind a physical barrier in the pill (center) so that it only gets released if the patient tries to abuse it by crushing/chewing it
What does the t-test determine?
Parametric test to determine if there is a significant difference between the means of 2 groups
What does the Kaplan-Meier plot tell us?
Distinguish between the duration of survival observed among those who died and the duration of survival among those alive at the end point of the observation period (y-axis: fraction alive, x-axis: time)
What is a parametric test?
Relies on the assumption that the underlying data being tested falls in a normal distribution
What are some common side effects to gabapentin?
Sedation, peripheral edema, and weight gain (relatively safe)
What side effect do you see with bisphosphonate medications like alendronate?
How does hyperthyroidism affect SVR, lusitropy, contractility, cardiac output?
Decreased SVR, increased lusitropy, increased contractility, increased CO
What cardiac finding do you see in almost 30% of patients with hyperthyroidism?
Atrial fibrillation (risk increases with age)
Would you see pericardial effusions with hyper- or hypothyroidism?
What would PFTs show in idiopathic pulmonary fibrosis?
Restrictive pattern (decreased FVC and FEV1, normal to increased ratio)
What do almost 85% of patients with idiopathic pulmonary fibrosis have?
Pulmonary HTN (from chronic hypoxia or hypertrophy of small pulmonary vessels)
What are the common anterior mediastinal masses?
5 T's: Thymoma, Thyroid tumor, Teratoma, Terrible lymphoma, and Thoracic aorta dilation
What is crucial with induction of GA with patients with compressive anterior mediastinal masses?
Maintenance of spontaneous ventilation (paralysis can cause collapse of airways)
What is the definition of acute kidney injury?
One of the following over less than 48 hours:
1. absolute increase in serum creatinine of 0.3 mg/dL or more
2. 50% increase in serum creatinine
3. Reduction of UOP to less than 0.5cc/kg/hr for more than 6hours
What is the traditional stimulus and response for SSEP? MEP?
SSEP: stimulus - median nerve, response - L/R scalp electrode over sensory cortex
MEP: stimulus - L/R scalp electrode over motor cortex, response - EMG in abductor pollicus brevis (APB)
Is the primary motor cortex anterior or posterior to the central sulcus? Primary sensory cortex?
Motor cortex: anterior
Sensory cortex: posterior
Do older patients require more or less hypnotic medication (i.e. propofol) and why?
Less because they have a reduced drug distribution, slower drug elimination from central compartment, and increased sensitivity to CNS depression
What is the difference between lean body weight and ideal body weight?
LBW: total body weight - weight of the fat
IBW: calculation based on sex, age and height
How should you dose propofol, fentanyl, remifentanil, succinylcholine, vecuronium, and rocuronium? Ideal body weight, total body weight, or lean body weight?
What are the fundamental differences between a pediatric and adult airway?
1. Relatively larger tongue
2. Larynx is more cephalad (C3-C4) vs adults (C4-C5)
3. Narrow, omega-shaped epiglottis
4. Anterior angulation of vocal cords
5. Narrowest portion is at cricoid ring vs adults (glottic opening) - may or may not be true now
What is the mechanism of action for the following: clopidogrel, dabigatran, ticlopidine, tirofiban
Clopidogrel/Ticlopidine: ADP receptor antagonist
Dabigatran: direct thrombin inhibitor
Tirofiban: IIb/IIIa receptor inhibitor
What coagulation factors are involved in the intrinsic vs extrinsic pathway?
Intrinsic: XII, XI, IX, VIII
Extrinsic: VII, III (tissue factor)
What nerve is injured if you have sensory loss of the 5th finger? Wrist drop? Loss of thumb Abduction?
What TEE view is the best for evaluating the coronary sinus?
Midesophageal (ME) 4 chamber view and the ME 2 chamber view
What TEE view is best for evaluating wall motion abnormalities of the LV?
Transgastric (TG) mid-papillary short axis view
Does the carotid body or carotid sinus act as a baroreceptor? Which acts as a chemoreceptor?
Baroreceptor: Carotid sinus
Chemoreceptor: Carotid body
What are common nerves affected by a carotid endarterectomy?
Recurrent laryngeal, superior laryngeal, and hypoglossal nerves
If you suspect pulmonary artery rupture from PA catheter placement when coming off CPB, what is the next step?
If minor hemorrhage: double-lumen tube and PEEP while weaning off CPB
If major hemorrhage: brochial blocker vs. double-lumen tube, possible lobectomy, temporary PA occlusion
What of the following agents would you avoid in patients with congenital QT prolongation: ondansetron, succinylcholine, propofol, glycopyrrolate, neostigmine
Avoid ondansetron (5-HT antagonist), glycopyrrolate & neostigmine, succinylcholine (K+ shifts and autonomic effects)
What is a normal carboxyhemoglobin level in cigarette smokers?
What is the treatment for acute carbon monoxide poisoning?
Supplemental O2, hyperbaric O2 if you have neurologic complications, myocardial ischemia, fetal distress in pregnant women, COHb >25%, any pediatric patient
Which medication would be best for a pediatric patient with a space-occupying brain lesion undergoing MRI who you want to be spontaneously ventilating: propofol infusion, IV midazolam/fentanyl, dexmedetomidine infusion, oral chloral hydrate
Dexmedetomidine infusion; the others cause decreased ventilatory drive causing increased PaCO2 leading to increased ICP; chloral hydrate is sedative that is usually ineffective in children >3 yo
What is a common side effect of dexmedetomidine?
Bradycardia (alpha-2 agonist effect)
What is the rate of atlantoaxial instability in Down Syndrome patients?
7% to 36%
Should children with Down Syndrome get cervical spine studies for atlantoaxial instability?
The American Academy of Pediatrics recommends getting studies for all patients between 3-5 years of age
How long can an ET tube be out of its packaging before it is not considered clean for tracheal intubation?
Up to 48 hours
Does airway equipment need to be sterile before intubation?
No, just need standard decontamination and disinfection
What are the 4 absolute indications for lung separation/one-lung ventilation?
1. Avoiding contamination from one lung to the other (i.e. pus)
2. Bronchopleural fistula or cyst rupture
3. Unilateral bronchopulmonary lavage (i.e in CF)
What is Osler-Weber Rendu Syndrome and what anesthetic complications do you have to worry about?
Hereditary hemorrhagic telangiectasia; autosomal dominant disease resulting in the absence of small capillaries -> multiple AVMs; can be in cerebral, pulmonary, or hepatic vasculature
How does pregnancy complicate Osler-Weber-Rendu Syndrome?
Enlarges the AVMs with weakened walls (increased CO and hormonal changes)
Which of the following is most likely to be present after a postdural puncture headache: tinnitus, photophobia, neck stiffness, hyperacusis?
What medications should be avoided in patients taking lithium?
ACE-I, NSAIDs, loop diuretics, and metronidazole
What is most likely to be the first manifestation of oxygen toxicity?
Retrosternal tightness -> cough -> decreased vital capacity + decreased DLCO (~24hrs)
What determines the onset of action of local anesthetics?
pKa and concentration (lower pKa and higher concentration has faster onset of action)
What determines the potency of local anesthetics?
Lipid solubility (increased = more potent)
What determines the duration of action of local anesthetics?
Protein binding (higher protein binding = longer duration of action) and addition of epi
What does adding sodium bicarbonate to local anesthetics do to the pharmacokinetics?
Increases pH which increases the amount of LA in the non-ionized form -> faster onset of action
Why has hydroxyethyl starch gone out of favor?
Increased risk of renal insufficiency/failure and increased mortality in critically ill patients
How long in advance must you quit smoking before you confer pulmonary benefits?
At least 4-8 weeks in advance
What effects do you see in smokers who quit 2-3 days before surgery?
Increased secretions and more reactive airways; decreased carboxyhemoglobin
What physiologic changes do you see in patients with autonomic hyperreflexia after stimulus?
Hypertensive and bradycardic with vasodilation
What patients are at risk of autonomic hyperreflexia?
Spinal cord injury at T7 or above
What is the advantage of a retrobulbar vs. peribulbar block?
Faster onset of action (retrobulbar > peribulbar)
How does paraplegia affect non-depolarizing neuromuscular blockade?
Increased resistance to non-depolarizing NMB
What does a full tank of N2O read and what volume does that correlate to?
750 psi, 1600L
When would you notice the psi to decrease in a tank of N2O?
When all the liquid form of N2O has been vaporized (~25% remaining = 400L)
At what voltage do you shock a pediatric patient during a code according to PALS?
First time: 2 J/kg, the resume CPR
Second time: 4 J/kg and resume CPR
What is the gold standard to rule out malignant hyperthermia?
Caffeine halothane contracture test
What anesthetic plan should you have with a patient who tested negative for malignant hyperthermia according to genetic test?
A negative test does not exclude susceptibility for MH and you should avoid all triggering agents
In a patient with elevated carboxyhemoglobin levels, how would the readings of a conventional pulse oximetry and a co-oximetry differ?
The conventional value would be higher than the co-oximetry value
Which NMB does not produce metabolites?
How is rocuronium excreted?
Unchanged in the bile
What is the mechanism of action for tapentadol?
Binds mu-opioid receptors, prevents reuptake of NE and 5-HT
What are the primary CV side effects seen with hypercalcemia?
Prolonged PR, shortened QT, HTN
What is the treatment for hypercalcemia?
1. IV fluids
2. Loop diuretic (avoid thiazide diuretics since they increased reabsorption of Ca)
According to the Revised Cardiac Risk Index, which of the following is associated with an increased risk of major cardiac event in the perioperative period: >70yo, hip fracture surgery, Hgb
Preoperative use of insulin; the 6 factors are:
1. Major surgery (intrathoracic, intraperitoneal, or aortic)
2. Hx of stroke/TIA
3. Ischemic heart disease
5. Preoperative use of insulin
6. Creatinine >2.0 mg/dL
What is the normal residual volume for a 70kg adult?
What is the normal FRC for a 70kg adult?
When is the cardiac output during pregnancy/labor is highest and why?
Immediately post-partum because of relief of caval compression and loss of maternal vascular resistance (placenta)
Which narcotic has the fastest onset of peak analgesia: sufentanil, alfentanil, fentanyl, or meperidine?
Alfentanil (highest fraction of nonionized drug at physiologic pH)
How does hypothermia affect plasma propofol concentrations? Fentanyl? MAC value?
Propofol: increases by 10% per 1C decrease
Fentanyl: increases by 5% per 1C decrease
MAC: decreased by 5% per 1C decrease
How does hypothermia affect coagulation?
Thrombin activity decreases and increased coagulopathy
What local anesthetic has the greatest risk of transient neurologic symptoms? Timing? Treatment?
Pain begins within 24 hours and resolves within 72 hours
Which surgical position has the greatest risk of transient neurologic symptoms?
Lithotomy (30-35% chance) compared to supine (4-8% chance)
Does lidocaine concentration affect the chances of transient neurologic symptoms? What about dose or baricity?
These are all independent of the risk of TNS
At what age do you normally see problems with patients with a bicuspid aortic valve? What is the most common complication?
Around 50 years old
Increased risk of developing an aortic dissection (single gene defect)
What cardiac findings do you see with Turner's syndrome?
Bicuspid aortic valves + Coarctation of the aorta
Do patients with a bicuspid aortic valve need endocarditis ppx?
Why would a patient be completely asymptomatic but have no pulse and no NIBP reading?
The patient has a nonpulsatile, continuous flow LVAD
Do patients undergoing a CEA have strokes?
Many will have embolic events but with no neurologic sequelae
What is a normal SaO2 for a healthy neonate within 5 minutes of delivery?
How does the cerebral autoregulation curve differ between a neonate and an adult?
The neonates curve is shifted left and down (lower CBF)
What are the steps for treatment of DKA?
Intubation of AMS
IV insulin + continuous insulin
IV fluids (can have a fluid deficit up to 10L)
Potassium repletion (even though K+ is high, it is from intracellular shifts)
How do you calculate serum osmolarity?
(2 * Na+) + (BUN/2.8) + (glucose/18)
What stage of labor is increased by use of an epidural? Do epidurals increase the risk of C-section?
Stage 2 (full dilation to delivery of fetus) is increased
No increased risk of C-sections
All other stages of labor are NOT affected
What happens to the acetylcholine receptors when you have third degree burns? Are they more or less resistant to non-depolarizing NMB?
Increased fetal and adult nicotinic Ach receptors; fetal Ach receptors are easier to stimulate and stays open longer allowing for more potassium to leave the cell (higher risk of hyperkalemia)
More resistant to non-depolarizing NMBs (more receptors to hit + fetal Ach receptors are more resistant)
When do you worry about succinylcholine-induced hyperkalemia after a burn? When is it thought to be safe to use succ after a burn?
After 24 hours
Waiting period is 1-2 years
What makes up the lumbar plexus?
Ventral rami of L1-L4 with variable contributions from T12 and L5
How are pacemakers described?
1. Paced chamber (A, V, D, O)
2. Sensed chamber (A, V, D, O)
3. Response to sensed chamber (I, T, D, O)
4. Rate modulation
5. Multisite pacing
Explain how a neuron maintains its resting potential and how local anesthetics play a role in stopping an action potential
Resting potential: -70 to -60 mV maintained by the Na/K pump and selective permeability of K+ to leave the cell
LA: block voltage-gated Na channels, not allowing for the influx of Na
What PFT parameter is normal in a patient with ascites?
FEV1/FVC ratio (since both FEV1 and FVC are decreased as seen in restrictive lung diseases)
What does the C5 nerve root innervate? What happens if you injure the C5 nerve root?
Deltoid (axillary nerve), supraspinatus and infraspinatus (suprascapular nerve), rhomboid (dorsal scapular nerve), biceps (musculocutaneous nerve)
What does the C6 nerve root innervate? What happens if you injure the C6 nerve root?
Innervation to thumb side of the hand, motor deficits in elbow flexion and wrist extension
What does the C7 nerve root innervate? What happens if you injury the C7 nerve root?
Motor to triceps and back of hand
Weakness of elbow extension, midscapular pain
What does the C8 nerve root innervate? What happens if you injure the C8 nerve root?
Ulnar nerve muscles
Handgrip weakness, loss of sensation to the 5th finger
How are ICDs described?
1. Chambers shocked
2. Chambers stimulated for antitachycardia pacing
3. Tachycardia sensing (either ECG or hemodynamic based)
4. Chambers stimulated for antibradycardia pacing
How does ingestion of garlic affect our anesthetic plan? When should it be stopped? What other herbs can do this?
Inhibits platelet aggregation (increased risk of bleeding)
Stopped 1 week before surgery
The G's (garlic, ginseng, gingko, ginger) + saw palmetto
Which anti-cholinesterase is used to reverse the effects of scopolamine?
Physostigmine (crosses the blood brain barrier)
What condition causes an ascending paralysis and how is it treated?
Guillian Barre Syndrome
Tx: IVIG, plasmapheresis, mechanical ventilation if respiratory status is of concern
What medication should be avoided in patients with Guillian Barre Syndrome?
Succinylcholine (risk of hyperkalemia)
What hemodynamic worries do you have with Guillian Barre Syndrome patients?
Autonomic dysfunction (hyper/hypotension, brady/tachycardia)
What condition causes skeletal muscle weakness with repetitive use and what is the pathophysiology? Treatment?
Myasthenia gravis; auto-antibodies against Ach receptors
Tx: anticholinesterase drugs (i.e. pyridostigmine) -> corticosteroids -> plasmapheresis -> thymectomy
How does a patient with myasthenia gravis respond to depolarizing NMB? Non-depolarizing NMB?
Depolarizing: Resistance (decreased # of functional receptors)
Non-depolarizing: Sensitive (same reason)