IABP Flashcards
Intra Aortic Balloon Pump Therapy
2 primary goals:
Increase diastolic pressure
Reduce afterload
Allows heart to rest/recover
IABP is ONLY supplemental to native cardiac function, ie heart has to have it’s own native function (cardiac index > 1.5 to function properly).
how does IAPB increase diastolic pressure
Theory of counter-pulsation:
During diastole, the balloon inflates, displacing blood volume into the coronary arteries (which fill primarily during diastole).
During systole, the balloon deflates, thereby reducing pressure within the left ventricle, and thus afterload.
IABP device
Placed in sublclavian or femoral artery
into descending thoracic aorta.
Transducing cable and gas line for inflating/deflating balloon
May be set to work with every cardiac cycle, every other, every 3rd, etc (1:1, 1:2, 1:3…)
IAPB indications
Cardiogenic shock
For example:
…cardiac failure after related surgery
…severe mitral regurgitation (decreased afterload)
…perioperative treatment of complications due to MI
…Failed PTCA
IABP goals
Decrease workload (reduce afterload)
Decrease myocardial oxygen demand
Decrease afterload
Increase coronary perfusion
Improve cardiac output (Q)
Decrease or limit myocardial ischemia
Prevent or limit cardiogenic shock
(IABP Part 2)
IABP contraindications
Severe aortic insufficiency
…back-pressure against weak aortic valve sends blood back into left ventricle (and ultimately into lungs) instead of down coronary arteries.
Aortic aneurysm / Aortic dissection
…IABP could increase tension on aortic wall
Limb ischemia
…IABP limits blood flow - could be bad if they already have poor perfusion to extremities.
Thromboembolism
IABP inflation gas
helium
…small molecule.
allows for rapid gas transport (rapid inflation/deflation of balloon)
In the case of a balloon rupture, helium can diffuse into blood stream without causing further issues.
IABP sizing
sizing based on pt height
25cc, 34cc, 40cc, and 50cc balloons
Balloon ideally inflates about 90% of aortic diameter.
If pump fails, balloon needs to be manually inflated and deflated
IABP positioning
Placed in descending thoracic aorta
Should be positioned so that the tip is ~ 1-2cm below the origin of the left subclavian artery and above the renal arteries.
Should be confirmed by fluoroscopy or cxr
IABP monitoring
Monitor perfusion to left hand/arm
Monitor urine output
(migration of balloon could impair blood flow to renal arteries)
radiopaque marker should be within 2nd intercostal space
IABP inflation
Balloon inflates during diastole
Inflates immediately following aortic valve closure to augment diastolic coronary perfusion pressure.
…Inflates on dicrotic notch on arterial waveform.
Clinical implications of IABP inflation
Increased coronary perfusion pressure
Increased systemic perfusion pressure
Increased O2 supply to coronary and peripheral tissues
Increased baroreceptor response
Decreased sympathetic stimulation; causing decreased HR, decreased systemic vascular resistance, an increased left ventricular function.
IABP deflation
Balloon deflates during systole
Deflates just before ventricular systole to reduce left ventricular work
Deflation creates a “potential space” in the aorta, reducing aortic volume and pressure
Clinical implications of IABP deflation
Afterload reduction and therefore reduction of myocardial oxygen consumption
Reduction in peak systolic pressure, therefore a reduction in left ventricular work
Increased cardiac output
Improved ejection fraction and forward flow (normally 50-70%).
IABP triggering
It is necessary to establish a reliable trigger signal prior to starting therapy
Trigger signal tells the computer that another cardiac cycle has begun
IABP trigger signals
ECG
Arterial waveform
Internal pressure or pacer
IABP trigger (ECG)
ECG is default trigger for balloon pump
R wave triggers balloon to deflate
R-wave = ventricular depolarization
T wave triggers balloon to inflate
T-wave = ventricular repolarization
IABP trigger (arterial / pressure waveform)
IABP will inflate at dicrotic notch
(when aortic valve closes)
IABP will deflate just before systole
IABP internal pressure mode
usually post-surgery
IABP pacer mode
…only use if pt is 100% paced
IABP senses pacing spike to trigger deflation.
IABP cardiac arrest
If an IABP pt experiences cardiac arrest while using IABP therapy, you must change the trigger while resuscitation is attempted.
IABP will not provide circulation on its own
Change trigger to arterial pressure
…IABP will work with you during CPR
IABP frequency
1:1 - every beat is assisted (full therapy)
1:2 - tachycardia (>130) and weaning
1:3 - weaning
During transport, should be 1:1
BUT, during 1:1 therapy, we can’t see how well IABP is working.
Test question:
Which mode to assess effect of IABP?
Answer is 1:2, so you can see the difference between assisted and unassisted
IABP augmentation
how much volume of gas into balloon
50cc balloon has max of 50cc, but could use less volume for inflation during weaning.
During transport, always full therapy (full inflation volume).
IABP augmented pressure
aka IABP diastolic augmented pressure
Should be the highest pressure on waveform.
Goal is for systolic pressures to be 10-20 mmHg higher than bedside monitor
(IABP part 5)
Diastolic dip
Difference between unassisted diastole and assisted diastole.
Usually ~ 5-10 mmHg
Reflects reduction in afterload.
(IABP part 5)
Early IABP inflation
Inflation before full closure of aortic valve
Inflation prior to dicrotic notch
Diastolic augmentation encroaches onto systole.
Potential premature closure of aortic valve.
potential increase in LVEDV and LVEDP
Increased left ventricular wall stress or afterload
Aortic regurgitation
Increased MVO2 demand
(IABP part 5)
Late IABP inflation
Inflation of IAB after dicrotic notch
Sub-optimal coronary artery perfusion
(IABP part 5)
Early IABP deflation
ski slope appearance on deflation curve
Sub-optimal decrease in LV O2 demand
Poor afterload reduction
Chairs with no seat - make you want to leave early
(IABP part 5)
Late IABP deflation
Most harmful balloon pump timing error
Assisted pressures higher than unassisted pressures (should be the opposite)
Increased afterload
Increased MVO2 consumption due to LV ejecting against greater resistance
(IABP part 5)
IABP timing modes
Automatic: tracks cardiac cycle and rhythm, adjusts accordingly.
Semi-automatic: operator can adjust inflation and deflation
(IABP part 5)
IABP troubleshooting
ECG trigger malfunction
…check pt leads
…change egg lead source
…switch to A-line source (pressure trigger)
Auto-fill failure
…Check helium level, refill if necessary; check balloon.
…Rust flakes (blood) in pressure line
…Balloon may have ruptured.
Pump failure
…If balloon is immobile >30 minutes, auto-fill every 5 minutes (to prevent clotting)
(IABP part 5)
IABP auto-purginng
Completely empties helium from the gas line.
Auto purge and fill balloon when atmospheric pressure changes by 25-50 mmHg
Pressure changes occur every 1000 ft rise or 2000 ft drop in altitude
Problem: could run out of helium if the machine automatically auto-purges with altitude changes.
Prior to transport, need to make sure the portable pump has been filled with helium (depends on device manufacturer).
IABP complications
Limb ischemia; thrombosis; emboli
Bleeding at insertion site
Groin hematomas
Aortic perforation and/or dissection
Renal failure and bowel ischemia
Neurological complications ie paraplegia
Thrombocytopenia
Cardiac arrest - switch from ECG trigger
IABP assessment
Assess left radial pulse every 15 minn
Assess urine output
Assess insertion site every 15 minutes
Document augmentation
Document assisted and unassisted IABP
…mean
…diastolic augmentation
…diastolic dip
Maintain HOB <30 degrees
Log roll, re-zero and fast flush every hour
IABP quiz
Primary trigger used for IABP operation is: ECG waveform
During IABP transport, pt changes from NSR to a-fib @ 110 bmp. You can expect IABP to: adjust to R wave deflation
Diastolic dip represents: afterload reduction
Gas Loss alarm: check for blood or rust-colored flakes in balloon tubing and verify HOB is not elevated greater than 30 degrees.
Which pressure is augmented by IABP deflation? LV end diastolic pressure.
