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The low flow alarm is set. This should be set at approximately 75% of the desired clinical flow.
There is air circulation around the motor and console.
There are two tubing clamps near each pump.
Staff should periodically rehearse switching to the backup motor and console using a spare system and training (mock circulatory) loop.
Refer to the CentriMag Circulatory Support System Operation Manual for details.
Hemodynamic Assessment and Support
Hemodynamic monitoring during support with the CentriMag system has some special considerations. During LVAD support, the
arterial pressure waveform will normally show a significantly reduced pulse pressure (Systolic-Diastolic) when the left ventricle is
completely unloaded. An increase in the pulse pressure will be observed as the ventricle recovers, when the pump flow is decreased,
or if the volume status of the patient is increased. A similar change will be seen on the pulmonary artery waveform during RVAD
support.
Pulmonary artery catheters may prove useful for monitoring during CentriMag system support, but there are some important
considerations during RVAD support. First, because the pulmonary artery catheter is inserted and maintained in position with the aid
of blood flow through the right heart, insertion of a catheter during RVAD support is usually not possible. Pulmonary artery catheters that
are in place before RVAD implant may be used for pressure monitoring and mixed venous oxygen saturation only, but often can migrate
out of the pulmonary artery. Thermodilution or continuous cardiac output determinations are inaccurate during RVAD support.
Since the inflow and outflow cannulas are placed in the right atrium and pulmonary artery, the majority of the circulating blood
travels through the pump circuit, rendering the pulmonary artery flow measured by the catheter incorrect. The RVAD flow bypasses the
thermistors that measure the temperature changes needed for the cardiac output measurement. However, in most cases the mixed
venous oxygen saturation may be used to estimate changes in total cardiac output based on the Fick principle.
CAUTION: The usual thermodilution methods for measuring total cardiac output might be inaccurate, and pump flow may
not represent total cardiac output. Although the CentriMag system may capture the majority of blood flow, some
ventricular output may be through the aortic or pulmonic valve. CentriMag system flow may also be elevated due to shunts
or incompetent valves.
Adequate volume is essential for pump operation. Fluid balance should be routinely monitored using patient weight, CVP, LAP, and/or
PCWP, with careful attention to intake and output.
If there is significant diuresis, intravascular fluid shifts or bleeding, this will adversely affect the available blood volume needed to
operate the system, and the flow may need to be temporarily reduced while these conditions are treated. If a CVP catheter needs to be
placed during CentriMag system support, care must be taken to avoid air entrainment during placement. Consider temporarily
decreasing the RPMs during insertion. This will make it easier to see the IJ or subclavian. Place the patient in the Trendelenberg
position, if tolerated. Be sure there are no signs of negative pressure during insertion (line chatter, ramping of the flows, or flow
below the minimum alert). Place a stopcock on the open ports of the central line to avoid air being entrained.
CAUTION: Never leave any ports open to the air, as sudden suction could result in air entrainment and the subsequent air
embolus will be delivered to the patient.
Bleeding is a common complication following CentriMag system placement and should be carefully monitored. Excessive bleeding that
does not decrease may require a reoperation. Constant attention must be given to maintaining a normal hemoglobin concentration.
Excessive diuresis in the post-operative phase should also be carefully monitored, and replacement volume administered as required.
Inotropic support is often used to support ventricular function, maintain wall motion, and reduce the risk of intra-ventricular
thrombosis, but should be used conservatively during CentriMag system support. High doses or prolonged use of inotropes may deplete
myocardial energy stores, making weaning and complete recovery more difficult. Milrinone is the usual drug of choice because of its
positive inotropic and vasodilatation effects. Inotropic support should be avoided during the initial weaning and assessments of
recovery, but gradually increased during the CentriMag system explant.
The pulmonary vascular resistance should be carefully monitored and treated when necessary. Because the PVR is not continuously
monitored, acute changes may not be observed. A sudden decrease in the LVAD flow is often caused by inadequate intra-ventricular
volume but may also be an indication of an elevated PVR due to administration of blood products, a response to an infusion, or other
cause. Pulmonary vasodilators are commonly used in the immediate postoperative period, with inhaled nitric oxide being the most
effective and safe. Patients with significant bleeding that require transfusions may be expected to have an increase in PVR. Many
CentriMag system users apply prophylactic nitric oxide and use intravenous vasodilators as a last resort.
Intra-aortic Balloon Pump
An intra-aortic balloon pump may provide pulsatility during CentriMag system support, but its usefulness with the CentriMag system
has not been demonstrated. If used with LVAD support, the augmentation or balloon volume should be decreased so that complete
occlusion of the aorta does not occur. Consider pulling back the sheath to improve distal perfusion, which should be assessed at least
hourly. The IABP may be removed in the critical care unit after coagulation parameters have normalized. If weaning is anticipated
within 48 to 72 hours, leaving the IABP in place may be appropriate.
Defibrillation/ Cardioversion
Defibrillation or cardioversion may be necessary during severe arrhythmias. Cardioversion may be performed without stopping the pump.
Ensure that a backup console and motor are available, powered and in the immediate vicinity.
If cardioversion is attempted without discontinuing support, consideration should be given to reducing the speed of the pump (or
pumps for BiVAD support) to reduce the likelihood of Right-Left imbalance and pump inlet obstruction. Following cardioversion, slowly
increase the speed (or resume BiVAD support) while monitoring the patient's hemodynamics to ensure adequate volume available for the
desired flow.
CAUTION: If you choose to reduce the speed during cardioversion, carefully monitor systemic hemodynamics for adequate
