test 3 Flashcards
What is one of the main uses for the intra-aortic balloon pump?
- cardoigenic shock
Miocardial infarctions effect on the systolic phase
- a decrease in CO and SV -> hypotenstion -> decrease coronary perfusion pressure -> ischemia -> progressive myocardial dysfunction -> death
- a decrease in CO and SV -> decrease in systemic perfusion -> compensatory vasoconstriction (increase in afterload) -> progressive myocardial dysfunction -> death
Miocardial infarctions effect on the diastolic phase
- an increase in left ventricular end diastolic pressure ending up in pulmonary congestion -> hypoxia -> ischemia -> progressive myocardial dysfunction -> death
what is the intra-aortic balloon pump considered
- Cardiac ASSIST Device: Patient must be ejecting blood
- won’t keep a patient alive on its own
intra-aortic balloon pump components
1) Gas cylinder (He)
2) Gas supply unit
3) Monitoring system
4) Control unit
- duel lumen = gas and blood compartment
IABP Treatment for:
Cardiogenic shock postmyocardial infarction - bridge to reperfusion therapies
Acute myocardial ischemia / Unstable angina
Acute cardiac defects - bridge to emergent surgery
Bridge to transplant/assist device implant
Perioperative support of high-risk cardiac and general surgical patients
Weaning from CPB
Stabilize high-risk patient for PTCA (balloon that clears out plaque from the coronaries), stent placement & angiography
Pharmacologically intractable ventricular arrhythmias
Septic Shock*
Contraindications - Absolute
Thoracic or abdominal aortic aneurysm
Dissecting aortic aneurysm
Severe aortic insufficiency - regurgitation
Major coagulopathies (bleeding is major problem)
Underlying brain death
End-stage diseases
Advanced or terminal neoplastic disease
Contraindications - Relative (at the surgeon or caregivers choice)
Severe aortic or femoral atherosclerosis
Symptomatic peripheral vascular disease
Intra-Aortic Balloon Insertion Sites
1) both right and left femoral artery (main insertion sites)
2) abdominal aorta
3) ascending or descending aorta (will have to leave chest open)
4) right subclavian
how does the balloon inflate?
- Base to tip
- As balloon expands, it displaces the same amount of blood pushing it toward the tip.
- designed to be put in retrograde
Percutaneous Insertion Seldinger Technique: Step 1
- after palpating the artery, the physician inserts an 18 gauge angiographic needle through the skin and into the artery
Percutaneous Insertion Seldinger Technique: Step 2
- The physician removes the stylet from the angiographic needle, and inserts the guidewire through the needle and into the artery.
- The guidewire is advanced up into the descending aorta so the tip of the wire is above the bifurcation of the aorta
Percutaneous Insertion Seldinger Technique: Step 3
- The physician removes the angiographic needle from the artery, and then placing a dilator on the guidwire, advances the dilator into the artery.
- The dilator is removed and replaced with the sheath-dilator assembly
Percutaneous Insertion Seldinger Technique: Step 4
- The dilator portion of the dilator-sheath assembly is removed.
- Physician removes the central lumen stylet from the balloon, places the balloon catheter over the guidewire, then advances the balloon catheter through the sheath and into the artery.
- The balloon is then advanced into the proper position within the descending aorta
- Use TEE to make sure the tip of the balloon is right where you want it
Arterial Cut-Down (Surgical)
- done in the femoral artery
- make incision and expose femoral artery
- make incision in it
- insert the balloon
- get it into the right position
- put a flexible graft onto the outside of the vessel and secure that down to prevent any bleeding
Benefits of doing a surgical insertion
- Direct visualization
- Less vessel trauma
- Less catheter kinking
- Applicable for patients with peripheral vascular disease
Risks of doing a surgical insertion
- Bleeding
- Thromboembolism
- Infection
- Increased insertion time
- Requires surgical removal
Benefits of doing a percutaneous insertion
- Increased speed of insertion
- Performed throughout hospital
- Less bleeding
- Decreased incidence of distal thromboembolism
- Decreased risk of infection
Risks of doing a percutaneous insertion
- Lack of vessel visualization
- Potential increased vessel trauma
- Increased chance of thromboembolism during removal
- Increased chance for dissection
- Not applicable for patients with peripheral vascular disease
Proper Balloon Position
- the tip of the balloon should be at the junction of the aortic arch and the descending aorta
- about 1 to 2 cm below the left subclavian artery
- on X-ray
- top of the balloon at the center of the second intercostal space
- bottom of the balloon should be at the L1 vertibrae
What is possible if the balloon is too low
- could occlude their renal ateries resulting in no renal blood flow which leads to renal failure
How occlusive is the balloon in the aorta
- want it to be 80 to 90% of the diameter of the patients aorta
- not completely occlusive or could result in:
- damage to aorta
- block blood flow
- platelet activation
Goals of Balloon Pump Treatment
- increase supply and decrease demand Increase cardiac output Decrease myocardial work Decrease myocardial oxygen demand Decrease myocardial ischemia - all done by volume displacement
Inflate the balloon during
- diastole
Deflate the balloon during
- systole
Balloon Counterpulsation
- Generation of a balloon pulse that is synchronized to occur opposite the cardiac cycle.
Heart creates pulse during systole
Balloon creates pulse during diastole
Goal of Counterpulsation
Inflate balloon during diastole
Deflate balloon before ventricular ejection (during isovolumetric contraction => right at the peak of R wave)
Purpose of Trigger Logic
- Synchronizes the patient’s cardiac cycle of systole and diastole with the balloon pump’s cycle of deflation and inflation
Trigger Logic
Tells pump console when the patient’s heart has entered systole
Provides starting point for timing logic
Provides mechanism to ensure that balloon will not be inflated during systole
Triggering information HAS to be provided by the patient
Triggering Options
Electrocardiogram
Senses the rate at which the ECG voltage changes
Usually upstroke of R wave satisfies the criteria
What if the patient has a pacemaker => pacer spikes will do the trick
Pressure (if patient doesn’t have and EKG like during CPR)
Senses the rate at which the arterial blood pressure changes
Internal (patient doesn’t have either)
Optimize ECG Triggering
Maximize amplitude of R wave
Do not need (or want) a diagnostic ECG
Minimize amplitude of other waves
Avoid electrical interference
Establishing Optimal ECG Trigger
Skin preparation
Use silver-silver chloride electrodes
Consider lead placement
Where to connect the IABP to get an EKG reading
- add to anesthesias monitor using a slave cord to trigger off of that
Where to connect the IABP to get an EKG reading when the case is over
- put the 4 to 5 leads on and switch the balloon back over
Optimize Pressure Triggering
You can measure patients aortic pressure from the tip of the balloon (internal lumen)
Prevent catheter whip
Prevent over damping of
waveform
Fiber-optic (at the tip) IAB catheters
Automatic in vivo calibration
Every 2 hours
Instantaneous signal transmission
Consistent and accurate arterial blood pressure waveform
Purpose of Timing Logic
- Used to set the precise inflation and deflation points
Timing Logic
Separate controls for setting inflation and deflation
Act as timers
Affected by trigger source
Set inflation point first, then set deflation point
Changing inflation point will affect timing of deflation point
Proper timing can ONLY be verified by looking at the patient’s arterial waveform (have to compare it to the patients native arterial waveform)
Effects of Balloon Inflation on the Proximal Compartment
Increased perfusion pressure at the coronary ostia
Increased diastolic pressure in the aortic root
Coronary blood flow may increase
Collateral coronary circulation may open
Increased perfusion to head vessels
Effects of Balloon Inflation on the Distal Compartment
Increased peripheral runoff
Increased systemic perfusion
Magnitude of effect depends on position of balloon tip (toward head or toward legs)
Effects of Balloon Deflation
Rapid reduction in aortic pressure
10 to 15 mmHg decrease in pressure (afterload)
- decreases pressure in the aorta so the aortic valve opens earlier
Isovolumic Contraction
- using the IABP reduces this phase
- This is where 90% of the oxygen consumption occurs
- therefore reduces the oxygen consumption
Effects of Decreased Afterload
Cardiac work is decreased
Maximum tension developed by ventricle reduced
Myocardial oxygen consumption is decreased
Balance between myocardial oxygen supply and demand may be restored
Factors that effect the demand
- DECREASING THE LV WALL TENSION
- myocardial contractility will increase the demand
- heart rate will increase the demand
- the heart is ejecting faster and less time for diastole so the filling is reduced - we reduce the afterload so decreasing LV wall tenstion by using the IABP
Factors that effect the supply
- INCREASING DIASTOLIC BLOOD PRESSURE AND DECREASING LV INTRAMURAL PRESSURE
- myocardial O2 uptake
- LV intramural pressure
- when intramural pressure is greater you have less blood flow down the coronaries and putting a greater pressure on the coronaries
- it is reduced by using the IABP - coronary flow
- Diastolic BP
- we are augmenting with the IABP (when it deflates we are raising the diastolic P)
Endocardial viability ratio
= Diastolic pressure time index (supply) / time tension index (area under LV systolic curve or demand)
- the goal is to increase the ratio
- anything less than 0.7 is severe myocardial ischemia
