Transcript Intra-Aortic Balloon Pump What it is and what it does

Intra-Aortic Balloon
Pump
What it is and what it
does
Don Stroup, CC/NREMT-P
Poudre Valley EMS
Objectives
• This presentation is intended to increase
your existing knowledge on the care and
transport of patients receiving IABP
therapy.
• Please keep in mind this information does
not replace formal didactic and hands on
training.
When IABP is used, and when it’s
not
• Indications
– Cardiogenic Shock
– Pre-shock syndrome
– Threatening extension of
MI
– Unstable angina
– Intractable ventricular
dysrhythmias
– Septic Shock
– Cardiac Contusion
– Prophylactic support
– Bridging device to other
mechanical assist
– Support during transport
• Contraindications
– Absolute
• Aortic Valve insufficiency
• Dissecting aortic
aneurysm
– Relative
• End-stage
cardiomyopathies
• Severe atherosclerosis
• End stage terminal
disease
• Abdominal aortic
aneurysm
• Blood dyscrasias
– Thrombocytopenia
The Cardiac Cycle
• The ventricles propel
blood throughout the
pulmonary and systemic
circulation as a result of
ventricular contraction.
• Fluid (blood) always flows
from high pressure to low.
• The cardiac cycle is
divided into systole
(ventricular contraction)
and diastole (ventricular
relaxation and filling)
http://www.nhf.org.nz/images/how_your_heart_works.gif
Preload vs. Afterload
• Preload refers to the amount of stretch on the ventricular
myocardium prior to contraction. Starling’s law
described how an increase of volume in the ventricle at
the end of diastole resulted in an increase in the volume
of blood pumped out.
– Preload is often referred to as “filling pressure”.
• Afterload is the resistance to ventricular ejection which
takes several forms:
– The mass of blood that must be moved, measured by the
hematocrit
• The higher the mass, the more inertia that must be generated.
– Aortic end diastolic pressure (AEDP).
• If the AEDP is 80 mm/hg, then the left ventricle must generate 81
mm/hg in order to open the aortic valve and generate blood flow.
– Arteriole resistance
Principles of the IABP
• A flexibile catheter is
inserted into the femoral
artery and passed into the
descending aorta.
• Correct positioning is
critical in order to avoid
blocking off the
subclavian, carotid, or
renal arteries.
• When inflated, the balloon
blocks 85-90% of the
aorta. Complete
occlusion would damage
the walls of the aorta, red
blood cells, and platelets.
http://www.fda.gov/cdrh/medicaldevicesafety/tipsarticles/balloon
pump.gif
Hemodynamics
• Helium is rapidly pumped into and out of the
balloon (about 40ccs). When inflated, this
balloon displaces the blood that is in the aorta.
– This is known as counter pulsation
– Helium is used because it is a soluble gas and will not
cause an embolus if the balloon ruptures
• This sudden inflation moves blood superiorly
and inferiorly to the balloon.
• When the balloon is suddenly deflated, the
pressure within the aorta drops quickly.
Hemodynamics (cont.)
• Inflation of the balloon occurs at the onset of diastole. At
that point, maximum aortic blood volume is available for
displacement because the left ventricle has just finished
contracting and is beginning to relax, the aortic valve is
closed, and the blood has not had an opportunity to flow
systemically.
• The pressure wave that is created by inflation forces
blood superiorly into the coronary arteries.
– This helps perfuse the heart.
• Blood is also forced inferiorly increasing perfusion to
distal organs (brain, kidneys, tissues, etc.)
Hemodynamics (cont.)
• The balloon remains inflated throughout
diastole.
• At the onset of systole, the balloon is rapidly
deflated. The sudden loss of aortic pressure
caused by the deflation reduces afterload.
– The left ventricle does not have to generate as much
pressure to achieve ejection since the blood has been
forced from the aorta.
– This lower ejection pressure reduces the amount of
work the heart has to do resulting in lower myocardial
oxygen demand.
Timing
• As you can see, inflation and deflation timing is critical in
order to obtain the maximum benefits from the pump.
• Incorrect timing can result in poor patient outcomes.
• During a cardiac arrest, the IABP can provide very
effective perfusion in conjunction with external
compressions.
– Since there is no ECG signal and no arterial pressure wave to
trigger the pump, an internal trigger is selected.
– This trigger detects the flow of blood caused by compressions
and inflates the balloon providing improved circulation.
– Good, consistent compressions are a must for this to work!
– Use of the Autopulse in these situations has not been studied.
Additional Resources
• For more information on counter pulsation
and the use of IABPs, use the following
link and review the information Arrow has
provided.
• http://www.arrowintl.com/products/educati
on/IAT009OL/
Resources
•
Arrow International (2005, May). Counterpulsation applied: an introduction
to intra-aortic balloon pumping. Arrow International Inc.: Pennsylvania