Oral Boards Flashcards
Restrictive Lung Disease Spirometry
FVC DECREASED
TLC DECREASED
FRV DECREASED
FEV1/FVC NORMAL or INCREASED
Obstructive Disease Spirometry
FVC NORMAL or DECREASED
TLC NORMAL or DECREASED
FRV INCREASED
FEV1/FVC DECREASED
Clinically relevant aspiration pH and volume?
- pH <2.5
- 25cc or more
What are common causes of hypoxemia?
decreased pulmonary capillary oxygen tension
- hypoventilation
- low FiO2
- ventilation/perfusion mismatch
- diffusion abnormality
increased shunting
- intrapulmonary or cardiac
reduced venous oxygen content
- congestive heart failure (low CO)
- increased metabolism (fever, hyperthyroid, shivering)
- decreased arterial oxygen content (anemia)
How long should you postpone elective surgery in a patient with asthma/COPD that has a URI?
airway hyperreactivity can last 2-8 weeks after infection in both healthy and asthmatics. At least 2-3 weeks is reasonable
Stress steroids?
- used if patients treated with systemic steroids for more than 2 weeks within the previous 6 months
- dose: 100mg hydrocortisone phosphate before induction, 100mg q8 hours x 48 hours
IV lidocaine dose, beneficial in airway disease?
- 1mg/kg 1-2 mins prior to intubation
paradoxical bronchospasm has been documented in asthmatics
- topical endotracheal lidocaine can work as long as patient is deep enough prior to LTA
What muscle relaxants cause histamine release?
d-tubocurarine, metcurine, succinulcholine, atracurium, mivacurium, doxcurium
what PaO2 should you maintain in COPD patients with supplemental oxygen?
PaO2 65mmHg; anything lower would increased PAP leading to right heart strain
Determinants of myocardial oxygen consumption
- HR
- contractility
- myocardial wall tension
Myocardial oxygen supply determinant
- arterial oxygen content
- coronary blood flow
What causes elevated Ppressure?
- bronchospasm
- anaphylaxis
- kinking of ETT
- mainstem intubation
- pneumothorax
- ARDS
- restrictive lung disease
How do you perform a Bier block?
Double tourniquet placed on the upper arm (forearm doesn’t allow adequate arterial pressure) and inflated 100 mmHg above pts BP. 1.5-3mg/kg of 0.5% lidocaine injected into the vein and IV subsequently taken out. Tourniquet must be up for at least 30 min; at most 90 min
Differential diagnosis of intraoperative oliguria
- kinked foley
- hypovolemia
- hypotension
- decrease ADH release (2/2 stress response)
- PPV
Cerebral Salt Wasting vs SIADH
Diabetes Insipidus
Both contain elevated urine Na and concentrated urine with decreased plasma Na
Cerebral Salt Wasting
- HYPOVOLEMIA
- polyuria
- tx: saline (isotonic or hypertonic), salt tabs, limit free water intake, +/- fludorocortisone
SIADH
- EUVOLEMIA
- oliguria
- plasma ADH elevated
- tx: fluid restriction, demeclocycline, furosemide
DI:
- HYPOVOLEMIA
- polyuria
- increased plasma Na concentration
- dilute urine
- tx: desmopressin (ADH) for central, HCTZ for nephrogenic
Anticoagulation stop prior to neuraxial
heparin: 6-8 hours with normal PTT
warfarin: 5 days and normal INR
lovenox (ppx): 12 hours
aspirin: no restrictions
Local Anesthetic Toxic Doses
lidocaine: 5mg/kg (7 mg/kg w/epi)
bupivacaine: 2.5 mg/kg
ropivacaine: 3 mg/kg
Mechanism of TXA
bind to lysine binding sites on plasminogen and fibrinogen and thereby inhibit plasminogen activator and plasmin release
inhibit fibrinolysis to prevent microvascular bleeding
Guidelines following ACS
- balloon angioplasty: 2 weeks
- BMS: DAPT for at least 30 d - 3 mos
- DES: DAPT for 12 mo
- MI: 6 mo for elective surgery
RCRI
- elevated risk surgery
- history of ischemic heart disease
- history of congestive heart failure
- history of cerebrovascular disease
- diabetes requiring insulin
- CKD with preop sCr >2
Cholinergic Crisis vs Myasthenic Crisis
Cholinergic: increased cholinergic activity
- bradycardia
- increased salivation
- pupils constricted
- tensilon test: symptoms exaggerated
- symptoms improved with atropine
Myasthenic: decreased cholinergic activity/decreased receptors
- tachycardia
- normal secretions
- normal pupil or dilated
- tensilon test: symptoms relieved
- symptoms temporarily improved with edrophonium
Pulmonary Embolism signs and diagnosis
Signs/Symptoms:
- dyspnea
- tachypnea
- chest pain
- palpitations
- low EtCO2
- S1Q3T3
Diagnosis:
- TTE/TEE
- d-dimer
- CTA PE
- V/Q scan
Jet Ventilation Pressure
pediatric: 5-10 psi
adults: 15-20 psi
increased until adequate chest excursions are noted
RCRI criteria
- elevated surgery risk
- history of ischemic heart disease
- history of CHF
- history of CVA
- preop insulin use
- preop creatinine >2
Bradycardia ACLS
- maintain airway, oxygen, IV access, EKG
- atropine (0.5mg), transcutaneous pacing, dopamine (2-20mcg/kg/min, epi (2-10 mcg/kg/min)
- consult cards, transvenous pacing
Tachycardia ACLS
- pulseless VT/VF —> SHOCK (unsynchronized)
- synchronized DCCV: afib, aflutter, SVT
- unsynchronized (defibrillation): pVT/VF or failure to synchronize
Tachycardia Algorithm
- maintain airway
- if unstable, regular narrow complex (adenosine) or DCCV
- if stable; adenosine, vagal maneuvers, CCB/BB
Triple H Therapy
- hypertension
- hypervolemia
- hemodilution
Neuroprotective Mechanisms
- propofol, barbiturate, etomidate gtt
- mannitol/furosemide
- mild hypothermia (32-34C)
Onset, Potency and Duration of LA
- onset: pKa
- potency: lipid solubility
- duration: protein binding
Pyloric Stenosis Electrolyte Derangments
- hypokalemia
- hypochloremia
- metabolic alkalosis
medical emergency, not surgical emergency. replace fluid first, then potassium (D5 1/2NS)
Sickle Cell Disease
- hemoglobinopathy leading to mutations on hemoglobin S and in presence of decreased O2 tension, deformation occurs
- increasing hct >30% is as effective as exchange transfusion
- avoid hypoxemia, hypotension, hypothermia, acidosis and hypovolemia
- tx: pain control, hydration, supplemental O2, maintain hct, exchange transfusion if hgbS >40%
Pregnancy Changes? CO SVR HR CVP PCWP
CO increases 40-50% above baseline; 80% right after birth
SVR decreases
HR increases
CVP, PCWP, PADP unchanged
murmurs normal in pregnancy?
- functional systolic murmurs occur in 90% of pregnancy
- diastolic murmurs are NEVER normal
Hemodynamic goals in mitral stenosis
- prevent tachycardia
- prolong diastolic filling time
- prevent AF
Fetal Decelerations…
- early: head compression
- late: uteroplacental insufficiency
- variable: umbilical cord compression
vonWillebrand Disease
- vWF synthesized in endothelial cells and bind to factor VIII
- prolonged BT, aPTT and platelet function
- treatment is DDAVP
- NO EFFECT ON TYPES 2B AND 3
Dantrolene MOA
- binds ryanodine receptor and decreases intracellular calcium concentration
carcinoid triad
- flushing
- diarrhea
- cardiac involvement (pulmonic stenosis or tricuspid regurg)
symptomatic carcinoid means metastasis bypassing the liver
postoperative jaundice
prehepatic: hemolysis; breakdown of hematoma, transfusion breakdown, CPB breakdown — increased bilirubin
hepatic: injury to hepatocytes; hypoxia, drug reaction, ischemia, sepsis
posthepatic: obstruction; stones, stricture, direct injury
lowering ICP
- elevate head of bed
- avoid agitation/anxiety/coughing
- mannitol 0.5g/kg (max 100g)
- mild hyperventilation (no less than 30 mmHg)
- mild hypothermia (32-33C)
TE fistula
- types A-E; most common is type C
- avoid ventilation through fistula leading to distention of stomach
- maintain spontaneous ventilation until corrected
- NG decompression prior to intubation
- catheter can be used to occlude fistula
Malignant Hyperthermia Treatment
- stop offending agents
- initiate dantrolene 2.5mg/kg every 6 hours
- increase fluids, may need lasix/mannitol to maintain UOP
- serial electrolytes, blood gas, creatine kinase, LFT, coags
- cool patient (not below 38C to prevent hypothermia)
- monitor patient in ICU for up to 72 hours for relapse, renal function and DIC
causes of atrial fibrillation
- idiopathic
- valvular
- CAD
- caffeine
- alcohol use
- hyperthyroidism
- LVH
- HTN
how does epinephrine help in anaphylaxis?
- alpha activity helps increase SVR
- beta activity relaxes bronchial smooth muscles
- beta increases cAMP to restore membrane permeability and decrease release of vasoactive agents
meds to avoid in LAST
- vasopressin: shown worse outcomes when used
- CCB: negative inotropy, slowed cardiac conduction, vasodilation
- BB: reduced blood flow to liver, negative inotropy and chronotropy
- LA: procainamide and lidocaine
What drugs should be avoided in a patient with pheo?
- increase in fasciulations: succinylcholine
- increase in histamine release: morphine, atracurium
- increase in sympathetic activity: ketamine, pancuronium, atropine, ephedrine
- droperidol, metoclopramide
FeNa
< 1%: pre-renal
> 2%: ATN/intrinsic disease
BUN/Cr
> 20:1 pre-renal
< 10:1 renal
Autonomic Hyperreflexia
- spinal cord lesion at T7 or higher
- noxious stimuli below level of lesion leads to uninhibited sympathetic response
- hypertensive leading to vasodilation and flushing above level of lesion with bradycardia
Antiemetic Drugs
- serotonin: ondansetron
- dopamine: metaclopramide, droperidol
- anticholinergic: scopolamine
- glucocorticoid: dexamethasone
- NKT antagonist: aprepitant
- histamine: promethazine
Effect of inhaled vs IV on ICP, CBF and CMRO2
- Thiopental, propofol, and etomidate all decrease CMRO2, ICP, and CBF
- inhaled reduce CMRO2, increase CBF
