ACE 2012 9A Flashcards
How frequent is neurogenic pulmonary edema noted and how quickly does it occur?
Up to 20% of patients with severe head trauma
Within 4 hours of injury
Thought to be caused by a massive sympathetic discharge after trauma
Left-sided DL tube placed for RULectomy with FOB, shortly after clamping, peak pressures increase and tidal volumes decrease… what’s the cause?
DL tube placed too distally
According to the AHA, what is the next step needed for a neonate with persistent bradycardia (HR
Epinephrine!
The first step with HR
What factors increase the risk of post-dural puncture headaches?
- Female
- Age 20-40
- Not using a pencil point needle
Where does the dural sac end in an infant? Where does a caudal epidural occur?
Ends at S3
Caudal is done at S4-S5
What is the first clinical signs of an infant with an accidental total spinal block?
Apnea and immobility (before changes in HR and BP)
In patients with severe mitral stenosis, what are they dependent on?
Preload and low heart rate (increased diastolic filling) with maintenance of SBP (to keep the trans-valvular gradient to allow for blood to flow from the LA to LV and maintain CO)
What is the ED50?
The dose required to achieve a drugs effect in 50% of patients
Which of the following is more frequently found in patients with SLE: seizures, asymptomatic pericarditis, renal failure, autoimmune hepatitis
Asymptomatic pericarditis (50% of patients) Seizures (20%), renal failure (3-12%), autoimmune hepatitis (5%)
What is the major side effect associated with the following: cyclophosphamide, methotrexate, mycophenolate mofetil
Cyclophosphamide: nephritis
Methotrexate: cutaneous SLE, arthritis, pulmonary infiltrates
Mycophenolate mofetil: nephritis, hemolytic anemia
Mechanism of action of clopidogrel? Ticlopidine? Dipyridamole? ASA? Tirofiban? Abciximab?
Clopidogrel/ticlopidine: inhibit ADP receptors
Dipyridamole: inhibits uptake of adenosine into platelets
ASA: inhibits COX-1 and thus prevents conversion of arachidonic acid to thromboxane
Tirofiban/abciximab: inhibits GIIb/IIIa receptors
When should pregnant women undergo surgery if absolutely necessary?
During 2nd trimester (preterm contractions and spontaneous abortions are least likely)
Is an epidural contraindicated in a pregnant women who has a history of spina bifida?
If there are no neurologic deficits, it is not contraindicated; if she has neurologic deficits, getting an MRI before can be considered
What is the main mechanism of action for gabapentin?
Binds alpha-2 delta subunit of the L-type calcium channel to stabilize the membrane
What is the dose of dantrolene in the treatment for malignant hyperthermia?
2.5 mg/kg
What should you avoid using in patients who have had vitreoretinal surgery and for how long after their surgery?
Nitrous (expands the air bubble and causes ischemia of the retina -> blindness) for 3 months at least
What is the major predictor of whether or not a patient will have cerebral vasospasms after a subarachnoid hemorrhage?
The amount of blood released
What is the mechanism of action for cerebral vasospasms after a SAH?
Breakdown of oxyhemoglobin causes increased release of endothelin (vasoconstrictor) and inhibition of nitric oxide (vasodilator)
What cardiac enzyme is the quickest to increase after an initial MI? Which enzyme would you use to see if the patient has another MI shortly after?
Quickest: Troponin I (rises within 2 hours, stays elevated for 7 days)
Re-infarct: CK-MB (rises within 3 hours, stays elevated for 1 day)
What is the diagnosis: patient with N/V, headache, photophobia, and pulsatile tinnitus?
Pseudotumor cerebri or idiopathic intracranial hypertension
What nerves are blocked with a retrobulbar block?
CN III, IV, VI
Eyelid is NOT blocked (as in a peribulbar block)
How would an air bubble in an ABG affect PaO2 and PaCO2 in a patient breathing room air?
- PaO2 will be increased (the air bubble is 21% O2 of 760 mmHg = 160 mmHg, this is higher than the PaO2 of someone breathing in RA so O2 diffuses from air bubble to the blood)
- PaCO2 will decrease (0.04% PaCO2 of 760 mmHg = 0.3 mmHg, this is lower than the PaCO2 so CO2 diffuses from blood to air bubble)
How does breathing change your blood pressure?
During inspiration, there is a small decrease in SBP (normal)
What is pulsus paradoxus and when do you see it?
Pulsus paradoxus: increased difference in SBP (>10 mmHg) between expiration and inspiration
Seen in cardiac tamponade, asthma, emphysema, obesity, PE
How does lisinopril affect potassium levels?
Increases K+ (decreases aldosterone release = less potassium excreted)
What is the most important predictor of post-op apnea in pediatrics?
Post-conceptual age (usually increased when
What should you do in terms of dispo with a patient who is 48 weeks post-conceptual age coming in for an elective procedure?
Watch for at least 12 hours after surgery
What are conservative treatment options for post-op apnea in children?
High-dose caffeine and theophylline (respiratory stimulants)
Which is most likely increased in Hashimoto’s thyroiditis: intravascular volume, chronotropy, SVR, inotropy
SVR; hypothyroidism causes decreased beta activity which leaves alpha activity unchecked -> increased SVR, increased DBP, and decreased pulse pressure
A decrease in cardiac output would affect the Fa/Fi ratio the least with which volatile anesthetic: Sevoflurane, Isoflurane, Desflurane, Nitrous oxide
Isoflurane (highest B/G coefficient and is thus the least soluble)
What is the expected glucose level of a 2 day old neonate? Hemoglobin level? Platelet count?
Glucose: 50-90 mg/dl
Hemoglobin: 15-20 g/dl
Platelet count: 250-450 x 10^3 /mm^3 (normal)
What factors are associated with a higher rate of radial artery occlusions with A-lines?
Longer periods of cannulation, non-Teflon catheters, females, size of the radial artery, number of puncture attempts, larger bore catheters, shorter catheters
Are males or females more prone to post-cardiothoracic surgery?
Males
What is the pathophysiology of myasthenia gravis and how are these patients affected by non-dopolarizing and depolarizing NMB?
Antibodies against nicotinic receptors
Less functional receptors: more susceptible to non-depolarizing and less susceptible to depolarizing
What is Lambert Eaton Syndrome and how are these patients affected by NMB?
Paraneoplastic syndrome with ascending paralysis (improves with repetitive use unlike MG) - antibodies against voltage-gated Ca channels (reduces ACh release)
Very sensitive to both depolarizing and non-depolarizing NMBs
What is the main cause of transfusion-related deaths in the US?
TRALI (transfusion-related acute lung injury) - more than 50% of mortality, rate is about 5-10%
What blood products are associated with a higher risk of developing TRALI?
Those that are plasma-rich (FFP > platelets > Cryo > RBC)
What is thought to be the underlying pathophysiology of TRALI?
Sequestration of neutrophils in the lungs + administration of blood containing high levels of leukocyte antibodies
What is the pathophysiology of hereditary angioedema? Acquired from ACE inhibitors?
C1 esterase inhibitor deficiency
Acquired: ACE inactivates bradykinin, so ACE inhibitors cause bradykinin accumulation -> increased vascular permeability
What screening test is most indicated in patients who have undergone doxorubicin chemotherapy?
Echocardiogram
What is the Bezold-Jarish reflex?
Patients with high resting vagal tone undergoing spinal anesthesia -> bradycardia and hypotension with cardiovascular collapse
What is the Bainbridge reflex? Difference between this and the baroreceptor reflex?
Increasing HR due to increased atrial stretch (IV volume loading or autotransfusion during birth).
Baroreceptor: stretch receptors on walls of arteries, carotid sinus and aortic bodies -> increased stretch -> decreased HR
What are the common signs of propofol infusion syndrome?
Metabolic acidosis, hyperkalemia, rhabdomyolysis, and progressive myocardial failure
How long should elective surgeries be delayed in patients with bare metal stents? Drug-eluting stents?
BMS: 1 month of ASA and clopidogrel
DES: 12 months of ASA and clopidogrel
What should be done if a patient with drug-eluting stents presents for an urgent or emergent procedure within a month of the stents being placed?
Emergent: Continue ASA and discontinue Plavix (restart as soon as possible after surgery)
Urgent: Plavix should be held for 5 days and restarted as soon as possible while ASA is continued
Where is core temperature best measured?
Nasopharynx, tympanic membrane, distal portion of esophagus, and pulmonary artery (via PA catheter)
What is the cross-reactivity between PCN and cephalosporins?
Up to 50% (but can be lower for 4th-generation cephalosporins)
What do you make of a EF of 65% in a patient with severe MR?
It is likely overestimated because a significant amount of the SV is being retrograded into the LA
What is the management goal of patients with severe MR? What drugs should you use?
Reduce SVR and increase HR
Dobutamine, low-dose epinephrine (where beta-2 effects predominate)
What factors determine placental transfer from the mother?
- Lipophilicity (more lipophilic = more transfer)
- pKa (more non-ionized form = more transfer)
- Size (smaller = more transfer)
- Protein binding (more binding = less transfer, albumin = less binding capacity, alpha-1 acid glycoprotein (AAG) = higher binding)
The least amount of placental transfer will occur with which drug: isoflurane, sufentanil, succinylcholine, ketamine
Succinylcholine: highly ionized so minimal transfer (as are most NMB drugs)
Isoflurane: lipid soluble and low MW so lots of transfer
Sufentanil: highly lipid soluble
Ketamine: highly lipid soluble and pKa close to pH (more non-ionized) = lots of transfer
How do halogenated volatile anesthetics affect uterine tone?
Decreases it in a dose dependent manner -> increased post-partum bleeding
Desflurane decreases tone less than sevoflurane
How does nitrous oxide affect uterine tone?
No effect; commonly used with halogenated agents to avoid decreased uterine tone
What is the FRC of an average adult? An average neonate?
Adult: 30 cc/kg (50% of total lung capacity)
Neonate: about 10% of TLC (they do have laryngeal breaking - termination of exhalation prior to relaxation volume which makes it ~40% of TLC)
What is the average O2 consumption of an adult? Of an infant?
Newborn: 6-8 cc/kg/min
Adult: 3-4 cc/kg/min
What is the total lung capacity of an average adult? Of an average newborn?
Adult: 6000 cc (~82 cc/kg)
Newborn: 160 cc (~63 cc/kg)
Which of the following is greater in a healthy adult than in a healthy newborn as a function of weight: tidal volume, total lung capacity, FRC, O2 consumption
TLC
How does your likelihood of a type II statistical error change with P-value?
Smaller P-value = higher probability of a type II error (false negative)
What value is required to calculate static compliance of the respiratory system?
Plateau pressures
What medication is preferred for uterine relaxation in the setting of a stable patient?
IV nitroglycerin (50-100 mcg): rapid onset and short duration of action
What cardiac abnormality is commonly seen with myotonic dystrophy?
1st degree AV block
Which of the following would precipitate a myotonic episode in a patient with myotonic dystrophy: rocuronium, hyperthermia, regional anesthesia, succinylcholine
Succinylcholine (also avoid etomidate); also worry about shivering (so avoid hypothermia)
How does chronic furosemide therapy affect: Na, K, Cl, Mg, Ca, CO2?
Na: increases K: decreases Cl: decreases Mg: decreases Ca: no change CO2: increases
Where do loop diuretics (furosemide, bumetanide, and ethacrynic acid) work?
Thick ascending limb of the loop of Henle -> blocks reuptake of Na/K/Cl from the Na/K/2Cl pump
What is the cause of pain during the first stage of labor?
1st: Dilation of the cervix and passive distention of the lower uterine segment
What is the cause of pain during the second stage of labor?
2nd: Visceral afferents to the cervix and lower uterine segment + vaginal canal and perineum stretching (S2-S4 nerve roots)
All donated blood gets tested for what?
- Hep B
- Hep C
- HIV
- Human T-cell lymphocytic virus
- West Nile virus
What is the basic thought process for treating hypotension in a patient with hypertrophic cardiomyopathy?
- Increase preload
- Increase afterload
- Decrease contractility
- Avoid tachycardia
A patient with hypertrophic cardiomyopathy becomes hypotensive during GA, what is the best drug to treat it: nitroglycerin, ephedrine, milrinone, esmolol
Esmolol: decreases contractility, decreases HR
Nitroglycerin will decrease preload
Ephedrine will help by increasing SVR and preload but will increase contractility (causing more outflow obstruction)
Milrinone will decrease SVR and increase contractility -> bad
What nerve root is affected if biceps reflex is altered? Brachioradialis reflex? Triceps reflex?
Biceps: C5-C6
Brachioradialis: C6
Triceps: C7
Which symptom along with bilateral lower extremity weakness is most likely to present in a patient with Guillain-Barre syndrome at the time of diagnosis: pain, hyperreflexia, fever, urinary incontinence
Pain (from inflammation of the nerves in the early phase; regeneration in the later phases)
You will have decreased reflexes in GBS
When is an early indication for intubation and ventilation in a patient with Guillain-Barre Syndrome?
Vital capacity -20 cm H2O
What is a side effect of sodium nitroprusside use?
Cyanide toxicity
What is the most reliable indicator of cyanide toxicity?
Metabolic acidosis (since cyanide binds to mitochondrial cytochrome oxidase and prevents aerobic respiration -> more anaerobic respiratory -> lactic acidosis)
What do you suspect if you see chocolate brown blood?
Methemoglobinemia
What is the treatment for cyanide toxicity?
- Sodium thiosulfate (increases metabolism of cyanide to thiocyanate -> renal elimination)
- Nitrites (causes a methemoglobinemia -> binds cyanide to form cyanmethemoglobin -> allows for aerobic metabolism to resume)
- Vitamin B12 (inactivates cyanide by chelating the cyanide ion)
What is the pressor of choice for pregnant women undergoing surgery?
Phenylephrine (does not compromise placental circulation) + fluids
What is the definition of mild preeclampsia? Severe?
Mild:
1. BP > 140/90 mmHg after 20 weeks gestation
2. Proteinuria of > 300 mg/24 hrs
Severe:
Mild + any of the following: BP >160/110 mmHg, proteinuria > 5g/24hrs, elevated creatinine, oliguria, pulmonary edema, HELLP syndrome, CNS symptoms, epigastric/RUQ pain, IUGR
What are the four main types of sickle cell crises?
- Vascular occlusion
- Hemolytic
- Sequestration (enlargement of liver/spleen)
- Aplastic (bone marrow suppression)
Which of the following is least likely to occur with sickle cell patients: cholelithiasis, chronic renal insufficiency, viral hepatitis, peripheral neuropathy
Peripheral neuropathy
Cholelithiasis (up to 70%), chronic renal insufficiency (up to 20%), viral hepatitis (up to 10% - likely from transfusions)
