CV Surgery Flashcards
What population is at higher risk for cardiac surgery and why?
Females older than 70, had protective estrogen so diagnosed later
Vasculature much smaller (targets)
What is the best indicator for post operative functional status in cardiac patients?
Ejection fraction
What is the gold standard in determining cardiac functional status?
Cardiac cath, gives a full picture of the coronaries
What interventions are used to decrease cardiac O2 utilization for CV surgery?
Anesthesia
Hypothermia
Electrical silence (cardioplegia)
Emptying the cardiac chambers, especially the LV
What technique is used to maintain adequate perfusion since the blood has a decreased viscosity from hypothermia?
Hemodilution and acceptable perfusion pressure
What two organs are at the most risk for injury from CV surgery?
The brain and kidneys
Why is it important to know if the CV patient has had a history of groin or leg vascular surgery?
These are used as graft sites or cannulation
What is the difference between HIT-1 and HIT-2?
HIT 1 usually not as bad self limiting
HIT2 worse and is cause by an immune mediated response
What drugs can be given if a patient is allergic to heparin?
Low molecular weight heparin or heparinoids
What is heparin resistance?
The need for greater amount of heparin to obtain the desired ACT
What can be given if a patient is heparin resistant?
AT III (in cryo)
What type of EKG should be in place for CV surgery?
5 electrode (7 leads), show two different lead on monitor at a time
Where are alternative sites for the pulse oximeter in CV patients?
Ear, lip or tongue
Where are arterial lines typically placed for CV surgery?
Radial unless using as bypass vessel conduit
What needs to be done before a TEE can be placed?
Empty the stomach
Why is it essential to monitor more than one temperature site during CV surgery?
Each temperature site measures different blood supply (vessel rich, vessel poor)
What are typically the three locations to monitor temperature during CV surgery?
The bladder, esophageal and skin
What should always be checked prior to placing an a-line?
The Allen test, measures collateral circulation to radial and ulnar arteries
At what temperature should the provider never warm the CV patient due to poor neurologic outcomes?
Greater than 37C
Why is the ulnar artery starting to be used more frequently as an arterial line site?
The radial can be used as a graft
Why is it preferred to place a left axillary a line if required compared to a right?
The left lies distal to the aortic arch and great vessels and decrease the risk of cerebral embolization
What two a line sites would resemble the aortic pressure waveforms?
Axillary and Femoral
What invasive monitor is a standard in monitoring CV surgical patients?
Pulmonary artery catheter
What is the most important application of CVP monitoring?
Provide an estimate of the adequacy of circulating blood volume and right ventricular preload
Where is the most common location to place a PAC?
The IJ, it is the most direct route
In what cases will the PAC not estimate LV?
Lung disease or Valve pathology
At what length is the provider expected to be in the RA, RV and the PA?
RA 10
RV 20
PA 30
How might the provider tell from the monitor that they have advanced from the RV to the PA?
The diastolic pressure is higher in the PA
Why don’t we typically wedge in CV surgery?
The catheter gets cold and there is a potential for the balloon to rupture
What pressure can be used in place of the wedge?
PA diastolic = wedge (unless pulmonary HTN and mitral valve function)
What can a wedge pressure of 20 indicate?
Normal compliance when given preload
External pressure
Stiff ventricle
What is the most common arrhythmia from PAC placement?
RV ectopy
Why is it so dangerous to place a PAC in a patient with a LBBB?
RBBB can be caused by PAC placements and then you have a total blockage
What is the most common complication of PAC placement from a subclavian approach?
Pneumothorax
What is the most common mechanical error from PAC placement?
Arterial puncture compared to venous
What is the most common life threatening complication of PAC placement?
Cardiac tamponade
Why are TEEs used?
Helps diagnose underlying mechanisms ascribed to several scenarios (ventricle filling, CO, tamponade, calcifications, thrombus)
What are contraindications to the used of TEE?
Esophageal pathology
If calcifications are found when performing TEE what does that indicate?
That the surgeon should not clamp the aorta because of the risk of breaking off and going to the brain
What are the most important TEE views?
Four chamber view Long axis view Two chamber view Mild short axis Basal short axis
What are specific recommendations for hemodynamics in patients with aortic and mitral stenosis prior to going on pump?
Maintain preload and SVR
HR 50-80 NSR
What are specific recommendations for hemodynamics in patients with aortic and mitral regurgitation prior to going on pump?
Maintain preload
Low SVR
Low HR 60-80 NSR
What CV med is given pre op as a standard of practice in CV surgery?
Beta blockers
Why is methylprednisolone given to patients that go on cardiac bypass?
To avoid pump syndrome
What type of patient population would be the best for a high narcotic technique?
Patients with a low EF
Why is nitrous avoided in CV surgery when bypass is used?
Any existing air is going to expand with nitrous
What causes cardiac depression in volatile anesthetics?
Alterations in intracellular Ca
What must the provider do prior to sternotomy?
Turn off the vent and deflate the lungs
Patients with what type of heart disease are at high risk for intraoperative ischemia?
Unfavorable coronary anatomy
Proximal coronary stenosis
Severe LV dysfunction
What artery is often used as a graft in CV surgery?
Mammary artery
What must be given prior to cannulation?
Heparin 300u/kg
Where should the PAC be pulled back to once on bypass?
RA
What chamber of the heart is most likely to be entered with sternotomy?
RV
How should the BP be manipulated prior to aortic cannulation?
SBP dropped to 80mmHg,decreases blood loss and decrease the chance of dissection
What vein is usually dissected for CV surgery?
Saphenous vein
What should the ACT be prior to going on pump?
> 400 seconds
How should heparin be given and rechecked?
Give in central line and wait three minutes to recheck ACT
What should be used as a guideline in reducing heparin?
The patient’s dose response curve should be used to calculate the amount of supplemental heparin needed to maintain ACT at a safe level on pump
What does the ACT measure?
The inhibiting effect that heparin and other anrtithrombotic medication have on the bodys clotting system (not actually heparin level)
When should protamine be given?
If the ACT is greater than 150 seconds at the end of the operation
When should an ACT be checked to ensure adequate heparin reversal?
15-30 minutes postoperatively
What is the fibrilatory threshold for temperature?
32 degrees, causes LV to expand and decreased subendocardial perfusion
Where are the two locations that cardioplegic solution is injected?
Aorta anterograde and Coronary sinus retrograde
How does hypothermia affect the blood?
Alters platelet function and reduces fibrin enzyme function
Inhibits initiation of thrombin formation
Reduces metabolic demand, increases tolerance to ischemia
What is the CPB machine usually primed with?
1500-2000mL of asanguinous fluid consisting primarily of a balanced salt solution
What is an acceptable Hct on pump?
20% and may be lower with Jehova’s Witness
Hgb 7
What factor independently determines post op renal failure on pump?
The degree of hemodilution is independently associated with post op renal failure
When should the provider turn off the vent when going on bypass?
When the PA goes flat
What are arrhythmias usually associated with when going on bypass?
Cardiac manipulation and cannulation
What are the most frequently encountered pre CPB problems?
Arrhythmias HTN HoTH Heart failure Bleeding
What affects does hypothermia have on the cells?
There is a favorable balance between O2 supply and demand
Decreased exicitotoxic neurotransmitter release
Decreased blood brain barrier permeability
Decreased inflammatory response
What are the initiators of the inflammatory cascade on pump?
Systemic cytokine signaling and complement system activation and Expression of cell adhesion molecules
What are the effectors of the inflammatory cascade on pump?
Margination of neutrophils, monocytes and platelets and the release of granule proteases
Where is the aortic clamp placed when going on bypass?
Above the aortic valve
How can the provider determine how diseased a patients heart is when going on pump?
They do not arrest quickly and often will see v-tach
What are hemodynamic goals for a patient on cardiac bypass?
Mild to moderate hypothermia (30-32) ad keep MAP at 50-70mmHg
What can occur in a patient with an incompetent aortic valve when going on bypass?
Cardioplegia will go forward into coronary arteries but also retrograde into the LV, this increases left ventricular end diastolic pressure and decreases CPP
How much potassium is in the cardioplegia solution?
26mEq/L
When are the two points to redose all medications during cardiac bypass?
Redose all agents when going on pump (dilutional effect) and when warming the patient
When is the most common for patients on bypass to have recall?
When rewarming the patient
What is the rule of thumb for the amount of time spent reperfusing a patient?
Reperfusion time should be half of the time spent on pump
What is thought to cause reperfusion injury?
Free radical mediated cellular membrane disruption
What is the purpose of using a partial occlusion clamp?
Allow some perfusion but still occluding some blood flow
How should an open heart be defibrillated?
Direct contact defibrillate at 10-13 joules
How should a provider treat a patient with an existing pacemaker prior to CV surgery?
Convert to asynchronous (using magnet) to ensure capture during chest entry
What should the provider do if the patient has a complete hear block when weaning from bypass?
Pace at 85-90bpm and make sure mA is acceptable
What are the ABCs of coming off pump?
Airway, turn on the vent
Bureaucracy, K, acid base, hematocrit and repercussion
C: Rhythm, a paced of V-paced need adequate rate around 90
Contractility make sure oxygen is okay before starting EPI
What is the best monitor for coming off bypass?
The eye, look at the heart you will see how vigorously it beats and
How can the provider calculate after load when the patient is coming off bypass?
Ask what the flow (CO)
What should the temperature be when complete rewarming?
Temp >35
What allergies are associated with protamine?
Salmon sperm, seafood and protamine zinc insulin
What is the mechanism of action of protamine?
Forms a tight ionic bond with the acidic sulfhydryl group of the heparin molecule on the basis of a 1:1mg ratio and prevents formation of H complex with AT III
Why does heparin rebound occur?
Protamine half life is shorter than heparin by 30-60m
What can occur if a dose 2-3x the normal reversal dose of protamine is given?
Has an anticoagulant effect
How should protamine be administered?
SLOWLY can cause type I, II and III hypersensitivity reactions
What should be done prior to closing the chest wires?
Shoot a CO to ensure everything is okay before closing
What are major challenges faced in post CPB?
Recall Bleeding Organ hypo perfusion Systemic inflammation response Residual hypothermia Repercussion inssues
What is the major cause of poor pulmonary outcome after cardiac surgery?
Cardiac dysfunction, low CO states directly and indirectly contribute to pulmonary dysfunction
How does CPB offer additional insults to the respiratory system?
Directly thought the activation of the inflammatory resins and indirectly through the decreased perfusion and lack of ventilation of the lungs
How are the kidneys affected post op by bypass?
Renal dysfunction remains a serious complication of cardiac surgery
What is the best way to prevent renal injury post bypass?
Maintain CO and perfusion pressure
How does hypothermia affect the patient post bypass?
Cold and SVR high, they look stable but intravascular volume is underestimated
What can further interfere with ventilation after bypass?
Shivering, increases O2 demand by 200-400%
Why might a patient experience hypokalemia after bypass?
Post CPB diuretics
What are typically the causes of acid base issues after bypass?
Low CO or elevated citrate levels
What acid/base issue is seen with SNP administration?
Cyanide toxicity are acidotic
Why might right ventricular dysfunction or failure occur after CPB?
Inadequate myocardial protection, inadequate revascularization with resultant right ventricular ischemia or infarction, preexisting pulmonary HTN, intracoronary or pulmonary air embolism, chronic mitral valve disease or tricuspid regurgitation
