BLOOD FLOW IN VA ECMO

• Provides a laminar flow of blood to the body because there is no pumping or pulsatility to the ECMO circuit.
• Oxygenated blood is returned retrograde to the heart in the aorta. This causes an increased afterload to the left ventricle. This is why VA ECMO should not be considered as resting the heart but rather providing circulatory support to the body.
• The lungs are not bypassed and therefore, are responsible for oxygenating any blood being pumped out of the heart.

PATIENT ASSESSMENT FINDINGS

• Pulses are not often palpable due to this fact. However, flow should always be detectable via doppler.
• The right radial artery is the closest arterial branch from the heart, thus is often the only place a pulse can be palpated. As the heart function improves you may feel a pulse on the left radial pulse to pedal pulses etc.

BLOOD FLOW IN VA ECMO

• The degree to which the heart is damaged, will greatly impact how much blood it is pumping out. Initially, the heart will be sicker and pump less, as the heart recovers, it will pump more.

PATIENT ASSESSMENT FINDINGS

• Due to lack of contraction – monitoring systolic and diastolic blood pressures is not accurate in VA ECMO. These numbers should only be trended. MAP goals should still be maintained and are the best indicator of systemic perfusion.
• Pulse pressure represents the force the heart generates as it contracts. this is crucial as we want the patient’s heart to have some pulsatility. A pulse pressure of 10-15 mmHg should be expected.

BLOOD FLOW IN VA ECMO

• A heart that has zero pulsatile activity causes blood to be stagnant which can lead to a devastating clot and causes left ventricle distention which worsens an already damaged myocardium.

PATIENT ASSESSMENT FINDINGS

• The arterial line and SpO2 probe should always be placed on the right hand to monitor heart function and adequate oxygenation.

BLOOD FLOW IN VA ECMO

• If the heart is starting to pump out blood we need to ensure that the lungs are being well ventilated and oxygenated so that they can oxygenate the blood being pumped out.

PATIENT ASSESSMENT FINDINGS

• ABGs should always be drawn from the right radial arterial line as it indicates the efficiency of the mechanical ventilator.

BLOOD FLOW IN VA ECMO

• It is vital to ensure that the head, brain, and upper extremities are getting well oxygenated blood (either from the heart or the ECMO circuit).
• The mixing cloud refers to the area where the blood coming from the native output of the heart mixes with the blood of the ECMO circuit.

PATIENT ASSESSMENT FINDINGS

• Monitoring SpO2 on the right hand provides information to the location of the mixing cloud. If the SpO2 on the right hand starts to decrease, then the mixing cloud may not be in the ideal location. Comparing to saturations on the left side and alerting the MD are crucial.