Pre-operative work up questions Flashcards
Name 6 risk factors for post operative renal dysfunction
Age Hypertension Diabetes Radiologic contrast complex surgery (AVR + CABG) ACE inhibitor pre-operative renal dysfunction
What type of analgesic should be avoided post op
NSAIDs
They interfere with prostaglandin function of the kidney
Name treatments for Hyperkalemia
1 gram of Calcium chloride IV
50 meq of Sodium Bicarbonate
10 u of Humulin R IV and 50 ml of D5W
30 gm po Kayexalate
What is malignant hyperthermia
Autosomial dominant with variable penetrance genetic disorder that results in increased skeletal muscle metabolism and CO2 production–hyperthermia/VT/renal failure
What agents can trigger Malignant Hyperthermia and what is the pathophysiology
Inhaled anesthestics (Halthothane, isoflurane)
Succinycholine
Possible association with ketamine
*impaired reuptake of inonized calcium from cytsol in the SR
List 4 viability scans
Myocardial perfusion imaging thallium or technetium PET Dobutamine echocardiography MRI CT
What is CHILD classification of liver failure and what is the mortality of patient with CHILD B
Based on 5 parameters Ascities PT (INT) Albumin Encpalopathy Bilirubin A is 5-6 B is 7-9 C 10 to 15 CHILD A is 0 to 3% CHILD B is 40 to 80% CHILD C is 100%
In patients with cirrhosis of the liver classified as CHILD B what is the mortality associated with a cardiac procedure involved the use of bypass
more then 70%
3 findings on stress thallium that an predict benefit of revascularization
Large reversible defect (which is also caused moderate-severe inducible ischmie, > 10 % of myocardium
Absence of fixed defects
Presence (and number of segments) of viable myocardium
What are contraindications to Dobutamine
Ventricular arrhythmias
Recent myocardial infarctions (1 to 3 days)
Acute coronary syndrome
Hemodynamically significant left ventricular outflow tract obstruction
Aortic aneurysm or aortic dissection
systemic hypertension
What is a dobutamine stress echo
Measure inotropic reserve of dysfunctional, but viable myocardium
viable myocardium shows improved regional contractile function
contractile reserve is independent of the severity of the coronary artery disease
mitral inflow pattern—early diastolic deceleration time (DT) of > 150 msec correlates with improvement after CABG and greater survival.
End-diastolic wall thickness of < .6 cm indicates non-viable segment
List 4 viability studies in order of accuracy
PET imaging highest sensitivity SPECT more sensitive than Dom echo excellent at predicting benefit from revascularization Dobutamine stress echo
Dobutamine MRI
How does thallium myocardial perfusion imaging for viability work
Thallium is take up by viable (living) myocytes (requires NA/K ATPase)
reflection of both perfusion and viability
Current protocols image at stress..redistribution..and reinjection (18 to 24 hours)
defect present in stress that recovers at late imaging indicates viability
List myocardial perfusion end points that are adverse predictors of future cardiac events
Large defect size > 20 percent of the left ventricle
defects in more than 1 coronary artery territor suggestive of multivessel disease
major nonreversible defects
transient or fixed left ventricular cavity dilation
resting left ventricular ejection fraction < 40 percent
increase lung uptake up thallium
What are risk factors for protamine reactions
history of a protamine allergy
Allergy to fish products
Previous exposure to protamine, even without a reaction
Use of NPH insulin
Prior vasectomy (immunologic exposure to sperm proteins after breakeage of the pats blood-sperm barrier.
Any allergy to other meds
What is risk of stroke per degree of carotid stenosis
<50% it’s a 2% risk
50 to 80% it’s about 7.5%
> 80% it’s about 11%
Unilateral occlusions it’s about 11%
Poor correlation between degree of audible bruit and the degree of carotid stenosis
What is mechanism of peri-operative stroke with carotid stenosis
Emboli from carotid plaque
Loss of pulsatile flow or inadequate perfusion pressure on bypass may lead to diminished flow distal to stenosis leading to “watershed stroke”
Prothrombotic state post-op leads to destabilization of previously asymptomatic carotid stensosis (as > 50% of cases occur > 24 hours post op)
Who should undergo carotid screening
Age > 65 Left main disease Peripheral vascular disease History of TIA/Stroke Carotid bruit on exam Smoking female DM Prior carotid endarectomy
What are the important outcomes from the carotid u/s to understand
- Peak systolic velocity (PSV)
- End-diastolic velocity
- Ratio between PSV in the internal carotid artery and the proximal common carotid artery (ICA/CCA ratio)
This ratio correct for baseline variation in hemodynamics (such as CO)
a ratio > 4 is equal to > 70%
What are options for carotid endarterctomy and CABG
Staged: CEA 1st–then 1 to 5 days after CABG (usually for those with less critical coronary disease
Combined: when severe CAD and would not tolerate CEA. Symptomatic for both lesion s
Reverse-staged: CABG then carotid–high rate of stroke (14%) while mortality is the same
What are AHA guidelines for CEA before CABG or concomitant
Class IIa
Symptomatic carotid artery disease or asymptomatic disease but stenosis of > 80% unilateral or bilateral
A patient presenting with MI. What are effects of timing on myocardium
- < 20 minutes of occlusion: reversible cellular damage and dpressed function with subsequent myocardial stunning
- > 40 min but < 3 hours. If reperfusion happens, 60 to 70% of ultimate infarct is salvageable
- > 3 hours but < 6 hours: salvageable myocardium decreases to 10%
- > 6 hours resulting in trans-myocardial infarction
List parameters of cardiogenic shock
SBP < 80 mmHg PCWP > 18 u/o < 20cc/hr metal state changes tachycardia peripheral vasoconstriction with cold extremities CI < 1.8 SVR < 200 dyn
What is prevalence and outcomes of presenting in SHOCK
most common cause of in-hospital mortality following MI
Mortality is 80%
Incidence in MI is 2.4 to 12%
results from loss of at least 40% of left ventricle
What is definition of NSTEMI
chest pain > 10 minutes ST-segment depression > 0.5 mm ST-segment elevation 0.6mm to 1.0mm T-wave inversion > 1 mm Positive troponin or history of unstable angina in a pt with CAD risk factors
Classify athersclerosis of the aorta
Type 1: circumferential calcification “Porcelain aorta”
Type 2: Diffuse intimal thickening with ragged friable edges. Unreliable palptation, easy to identify on TEE or epiaortic scan
Type 3: Intramural liquid debris. The most difficult to find by palpation or TEE. Best seen on epiaortic scan
An other classification used in TEE or epiaortic Grade 1: normal or mild, wall< 2 mm Grade 2: thickening 2-3 mm Grade 3: atheromatous protrusion < 5 mm Grade 4: atheromatous protrusion > 5 mm Grade 5: mobile plaque
What is a grading system for Epi-aortic scanning
Normal no intimal thickening
Mild < 3 mm without irregularities
Moderate > 4 mm with diffifuse irregularities and or calcification
Severe > 5 mm intimal thickening and or large mobile debris and ulcerated pla ques and thrombi
Describe role for pulmonary function test in preop
Help only in highlighting the degree of risk but do not provide definitive risk assessment for post operative complications.
FEV1 that is more than two standard deviations less then predicted is usually associated with a prohibitively high risk for pulmonary complications
Patient with post op AVR having hemolysis. What are tests that should be performed
Serum haptoglobin * best test* LDH Indirect bilirubin peripheral smear urine free hemoglobin urine hemosiderin
What pulmonary function tests are associated with high risk postoperative respiratory failure
P02 < 60 on room air PC02 if > 60 FEV1 < 65% of VC FEV 1 < 1 -1.5 L DLCO < 50% predicted Vo2 max > 10 cc/kg, the best predictor but rarely measured Failure to respond to broncho-dilators
Interpreting pulmonary function testing
The most important spirometric maneuver is the FVC. To measure FVC, the pt inhales maximally, then exhales as rapidly and as completely as possible.
Normal lungs generally can empty more than 80 percent of their volume in six seconds or less. The forced expiratory volume in one second (FEV1) is the volume of air exhaled in the first second of the FVC maneuver. The FEV1/FVC ratio is expressed as a percentage
How to distinguish between restrictive and obstructive pulmonary disorders
When the FVC and FEV1 are decreased, the distinction between an obstructive and restrictive ventilatory pattern depends on the absolute FEV1/FVC ratio.
If the absolute FEV1/FVC ratio is normal or increased, a restrictive ventilatory impairment
A reduced FEV1 and absolute FEV1/FVC ratio indicates an obstructive ventilatory pattern, and bronchodilator challenge testing is recommended to detect patients with reversible airway obstruction (e.g., asthma).
*use 0.7 as the FEV1/FVC ratio that is “normal”
What are parameters of bedside spirometry that indicate high risk
FEV1 < 70% predicted
FEVc < 70 % predicted
FEV1/FVC ratio of < 65%
What is definition of Cardiogenic Shock
BP systolic < 80mmHg mean < 60mmHg
CI < 2 L (with adquate filling)
LAP and/or RAP > 20
Clinical manifestation of low cardiac output
decreased peripheral perfusion (pulses, cool, mottled)
restlessness, confusion, decreased mentation
urine output < 20-30 cc/hr
In patients with pre-existing chronic renal failure and dialysis
a. What is the expected in hospital mortality associated with CABG
b. What is the two year survival (including mortality of all causese)
8- 13%
50 to 60%
In patients with pre-existing chronic renal failure and dialysis
What is the expected in hospital mortality associated withe coronary artery bypass surgery
What is the two year survival (including mortality of all causes)
8 - 13%
50 to 60%
