Misc Flashcards
BMI obesity classification
“Premedication” possibilities
- Reglan or antacid (Bicitra - citric acid) for aspiration
- Breathing tx (asthma)
- DVT ppx
- Abx
Would you give an obese pt versed?
“Would need to weigh risks/benefits with particular patient and see if there are any other measures they’d be okay with to decrease their anxiety (music, talking, etc) or possibility giving a bit of precedex instead - knowing that they are at higher risk of resp depression if have undiagnosed OSA. But also don’t want to cause increase in anxiety that could also lead to uncooperation/ineffective preoxygenation etc
How to calculate BMI?
To remember rough estimate…5’ 70kg person = BMI ~31 (5’ is ~ 150cm, which is 1.5m…1.5^2 = 2.25…70/2.25 = 31)
If height is in inches and weight in lbs, BMI = (lbs/in^2)*703
Remember 2.2lbs = 1kg
Fat embolism major/minor criteria and name
Gurd and Wilson:
petechiae
AMS
hypoxemia, pulm edema
unexplained thrombocytopenia, anemia
fat everywhere
tachycardia
fever
Tx of fat embolism?
- Give 100% FIO2
- Tx hypoTN and hypovol
- Give blood products PRN, keep ventilating
- Tell surgeon in case they’re able to shorten procedure
Explain MetHb and SpO2
- cyanosis typically doesn’t occur at a sat of 85%, more like 70%, so this can be a clue
- Traditional dual wave-length pulse oximetry is inaccurate in the setting of methemoglobinemia because these pulse oximeters measure the absorbance of light at two wavelengths - 660 and 940 nm. The ratio of this absorbance allows the distinction between oxyhemoglobin and deoxyhemoglobin, with the expressed percentage, or SpO2, indicating the measured amount of hemoglobin that is oxygenated. Methemoglobin has high absorbance at both of these wavelengths, leading to the interference that causes an inaccurate SpO2 reading. When the level of methemoglobin approaches 30-35%, the ratio of absorbance becomes 1.0. A ratio of absorbance (A660/A940) of 1.0 reads as a SpO2 of 85%.
Steps you’d take if your pt develops MetHb?
Most importantly, ID the oxidizing agent (benzocaine, prilocaine, etc) and stop it! Tissue hypoxia doesn’t occur until MetHb levels >30%. If levels were clinically significant though, would give 100% O2, consider exchange transfusion, and give methylene blue (or if G6PD def, ascorbic acid)
What is G6PD def? Symptoms, etc
- Sxs: Fatigue, cyanosis, jaundice, anemia, hypoTN, lumbar/abd pain, hemolysis (can have all the time, intermittently, or in presence of inc oxidants and free radicals like during illness/infection, certain meds, fava beans), hematuria, renal failure
Explain/draw out enzyme pathways relating to MetHb, methylene blue, and G6PD deficiency
- Basically, G6PD is needed to generate NADPH, which is needed for the methylene blue pathway to work, which converts ferric to ferrous heme
What does placing the pt in reverse T during induction do?
- Improves resp mechanics
- Dec risk of aspiration
- Facilitates venous drainage from intracranial compartment
What to do if poked with HIV pt? Transmission rate?
- Wash w/soap and water
- Contact employee health for blood draw
- rate w/perQ puncture = 0.3%
- will likely get postexposure ppx
- avoid transmissable activities until everything comes back
Myasthenia gravis sxs?
- dyspnea
- diplopia (dbl vision) –> blurred vision
- ptosis
- dysphagia
- difficulty chewing
- dysarthria (slurred speech)
- muscle weakness
How to dx myasthenia gravis?
- tensilon test (1st line. Edrophonium injx –> if muscle weakness improved with this AChE inhibitor, then might be MG)
- nerve stimulation
- AB immunoassays
“Bulbar sxs” - what are they, what sxs
- weakness in the muscles innervated by CNs V, VII, and IX-XII
- facial weakness, difficulty chewing, dysphagia, dysarthria
Risk factors (10) for CV periop complications for pts w/ant mediastinal mass?
- tracheal compression >50%
- ” “ >30% + bronchial compression
- stridor
- orthopnea
- cyanosis
- jugular distention
- SVC syndrome
- pericardial/pleural effusion
- combo obstructive + restrictive pattern on PFTs
Explain your overall method for evaluating severity of ant mediastinal mass preop?
Obviously H&P, focusing on:
- tracheal compression >50%
- “ “ >30% + bronchial compression
- stridor
- orthopnea
- cyanosis
- jugular distention
- SVC syndrome
- pericardial/pleural effusion
- combo obstructive + restrictive pattern on PFTs
…as well as:
Congenital effects seen with Down Syndrome pts that could effect airway?
- Macroglossia
- Atlanto-axial instability
- micrognathia
- subglottic stenosis
- could complicated mask ventilation, laryngoscopy, and ETT placement
2-3 major things to discuss with surgeon when about to perform anesthesia for a biopsy of a mass of some kind?
- what kind of biopsy is needed (e.g. for this mediastinal mass, are there any extrathoracic adenopathy, cervical/supraclav nodes available to do a much less invasive bx under LA instead of intrathoracic bx under GA)
- any chance of pt receiving chemo/radiation/steroids to decrease the size of the tumor prior to surgery if this would dec anesthetic risk, for example. However, rapid tumor lysis may affect accuracy of future histological dx so sometimes can’t
What can anticholinergics be used for in the OR?
- aspiration ppx (this seems like it was done in the past but no longer..they dec LEW tone and not shown to dec acidity/gastric volume - ASA no longer recommend)
- dec airway secretions
- dec airway hyperreactivity (asthma pt)
- obviously helps with bradycardia (esp if inducing w/inhaled sevo)
- random**: avoid anticholinergics in MG pts, as would lead to inc muscle weakness and bulbar sxs
How to eval someone for atlanto-axial instability?
- look at their previous anesthesia records/esp airway
- see if any neck radiographs-look for any subluxation (ant atlantodental interval > 4-5mm in any lat view)
- thorough H&P Re: s/s of cord compression (gait issues, paresthesias, fatigue when walking, and ask them to extend/flex neck to see if that elicits pain/motor/sensory deficits)
Pts with MG and Lambert Eaton…dosing of nondepols and depol agents?
- MG: will be RESISTANT to sux (not as many Rs available to create large depolarizing effect, so will need to give ~1.5x normal dose) and SENSITIVE to roc (the disease has already destroyed Rs so kind of already getting a head start on a nondepol mechanism)
- LE: lambs are SENSITIVE to both
Signs of cholinergic crisis?
- dyspnea
- constricted pupils
- weakness/muscle fasciculations
- brady
- salivation, N/V/abd cramps
- diarrhea, urinary freq/urgency
- diaphoresis
SEs of methylpred (or just high dose steroids in general)
- infx, impaired wound healing, immunosuppression, GI bleeding, resp compromise
- fluid retention, HTN, lyte imbalances, hyperglycemia,
**random side note: giving high dose steroids after acute spinal cord injury used to be recommended, but is no longer d/t lack of clinical benefit shown and all of the above named SEs
Alcohol w/d timeline and s/s?
- 6-8 hrs: tremors
- 24-36hrs: hallucinations/seizures
- w/in 72hrs: life threatening DTs (confusion, perceptual distortions, agitation, autonomic instability w/fever, tachy, HTN)
How would you proceed preoperatively with a chronic alcoholic?
- history: type, freq, quantity, and time of last alcohol
- PE: cirrhosis, HE, Wernicke-Korsakoff, gait issues, CM
- CBC, BUN, Cr, lytes, glu, coags, LFTs, ECG, CXR
- consider BDZ to prevent acute w/d
What effects does alcohol have on the body (esp those related to anesthesia)
- inc MAC, tolerance to drugs, cerebral atrophy/cerebellar degeneration, peripheral neuropathy, acute w/d sxs
- CM
- cirrhosis, GI bleeding, inc risk of aspiration (inc gastric acid, dec LES tone, delayed gastric emptying), nutritional deficiency, hypoglycemia
-thrombocytopenia, lyte abnlties
Risks of poor periop glu control?
Lab work you’d order for diabetic pt?
- worse neuro outcomes iso TBIs
- impaired wound healing, inc risk of infx, osmotic diuresis
- Just think of anything that would ID end organ disease…
- CBC, BUN, Cr, K, glu, UA
- possibly ECG (early atherosclerosis and silent ischemia in these pts)
Any special monitoring for spine cases?
- Remember SSEP and MEPs!!! Apparently, MEPs are not necessarily the standard of care yet technically, but have inc sensitivity than SSEPs so if spinal cord ischemia is a significant risk, you could always say that you wanted to dec the false negative rate that you’d have if only monitoring SSEPs, thus you’d want both.
- if >4 hrs, have to remember Foley
Describe with autonomic neuropathy is, and clinical manifestations?
- Longstanding, poorly controlled DM –> excessive glycosylation –> neuropathy of the ANS
- GI: gastroparesis, GERD, early satiety, bloating, N/V/D, epigastric pain
- extremities: peripheral neuropathy, no sweating
- CV: HTN, resting tachycardia, orthostasis, no reflex tachy w/hypovolemia, resistance to ephedrine
Causes of AGMA?
- MUDPILES: methanol, urea, DKA, paraldehyde, iron/isoniazid, lactic acidosis, ethanol/ethylene glycol, salicylates/ASA
When would you administer bicarb? Issues with doing it?
- if pH < 7.1, bicarb < 10, or if pt developed life threatening hyperK (bc can lead to dysrhythmias, hypoTN, myocardial dep, resistance to exogenous catecholamines)
-1) bicarb + H –> CO2 + H2O (additional CO2 diffuses into cells –> worsening acidosis).
2) leftward shift of curve –> less unloading of O2 at tissues
3) causing hyperosmolar state 2/2 excessive Na (review this?)
4) causing hypoK d/t extra- to intra-cellular movement
Causes of postop vision loss? (3)
Steps to take?
-PION: post ischemic optic neuropathy
- RAO: retinal artery occlusion
- cortical blindness
- all likely 2/2 impaired O2 delivery, so you should…
- assess and correct any metabolic disurbances, elevate HOB to facilitate venous drainage, ensure adequate BP/Hgb/oxygenation/cardiac fxn, ophtho consult
-ASA states NO role for antiplatelets, steroids, IOP lowering agents in periop ION
Describe PION - what it stands for, what it is, who is at high risk? How to reduce risk?
- posterior ischemic optic neuropathy
- postop vision loss (dec acuity to blindness) 2/2 dec O2 delivery to part of optic nerve –> nerve damage. Poor prognosis, presents w/in 24-48 hrs postop, painless vision loss/field defects/etc
- risk: prolonged procedures (>6.5 hrs), substantial blood loss (50% of blood vol).
Could dec risk by:
- head neutral or higher than heart
- monitor BP and keep near baseline (esp in HTN pts)
- consider CVP monitoring and admin fluids PRN
- monitor Hct levels
- consider staging long procedures (weighing risk/benefit)
Good way of describing decision to/not to get further cardiac evaluation if METS <4 or unknown + intervention would change management?
“I would consider pharmacological stress testing (e.g. dobutamine stress echocardiography to ID any myocardium at risk)”
Periop complications associated with DM?
- hyper/hypoglycemia
- hemodyn instability (autonomic neuropathy)
- silent ischemia
- neurologic injury
- aspiration
Potential deleterious effects of hypothermia?
- inc O2 consumption
- inc PVR (+ possible cardiac shunting if have PFO, VSD, PDA)
- altered drug response
- postop hypovent, apnea
- coagulopathy
- delayed emergence
- cardiac irritability
- impaired wound healing
- metabolic acidosis
What’s a good framework for answering the question “what concerns do you have in providing anesthesia to this patient”?
- first, state the urgency of the case if it’s urgent or emergent, “since this may limit the time I have to evaluate and optimize the patient”
- think through in your head all of the data you’ve been given about the patient and every possible issue that is r/t his PMH etc…he’s at “inc risk for ___ d/t his ___ disease”
- any particular concerns about the type of surgery itself or what they have to do for it
Name the signs of hyper- and hypo- volemia
Hypervol: peripheral edema, pulm edema, elevated JVD, HTN
Hypovol: dry mucous membranes, poor skin turger, hypoTN, orthostasis
What’s a good way to approach the questions where they ask if you would cancel the case due to a lab value or whatever?
- “Assuming nothing terrible is happening (like symptomatic from said lab derangement, EKG changes, etc), I would not cancel the case due to the urgency of the procedure
- However, I understand that ___ has the potential to ___
- Therefore, I would do these things to prepare/help the situation in general
- Proceed with the case and monitor closely for signs of really bad stuff”
Preop labwork you’d order for a pt with chronic renal failure?
- CBC (anemia)
- lyte panel (Na, Ca, K)
- ECG (hypertrophy, ischemia, conduction abnlties)
- CXR (fluid overload, pulm status)
- if dyspneic, ABG
- if regional, coags
Describe how you would induce a patient whom you are concerned about aspiration in?
- insert NGT
- aspiration ppx
- reverse T to improve resp mechanics, dec passive regurg, facilitate rapid intubation
- pre-ox w/100% FiO2
- if reassuring airway, RSI w/cricoid pressure