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AC adjustments that make a difference

With therapeutic plasma exchange (TPE) and red blood cell exchange (RBCX) procedures on the Spectra Optia® Apheresis System, you can configure the inlet:AC ratio and ACIR before starting the procedure.

Knowing how to adjust values during the procedure — based on the tolerance of the patient (for ACIR) or any observed clumping in the extracorporeal circuit (for inlet:AC ratio) — can make a difference in the outcome.

Beginning with the inlet:AC ratio, it is recommended that you initially configure the ratio at the default value, which varies depending on the type of procedure you are performing.

For TPE, the default inlet:AC ratio is 10:1.
The inlet:AC ratio is the proportion of inlet volume to AC volume — or the number of pump rotations of the inlet pump relative to the AC pump. It determines the concentration of anticoagulant (AC) in the extracorporeal circuit.

The number of parts of whole blood in the inlet volume is determined by the inlet:AC ratio you select in the Spectra Optia system. With the Spectra Optia system, the inlet volume is always composed of one part AC and the corresponding parts of whole blood (inlet:AC ratio).

Because most of the blood volume is plasma, most of the AC is removed along with the patient's plasma when blood is separated during a TPE procedure. Therefore, the AC a patient receives with a 15:1 ratio is not much greater than with a 10:1 ratio. The chart below shows some examples.

For RBCX, the default inlet:AC ratio is 13:1.
You can change the inlet:AC ratio at any time during TPE or RBCX to address the anticoagulation needs of the procedure — but only after you carefully consider the effects on the exchange.
  • If you enter an inlet:AC ratio higher than the default, monitor the channel closely for clumping.
  • If you enter an inlet:AC ratio higher than 15:1, you will see an advisory message that you are exceeding the recommended limit.

It is important in any procedure to monitor for clumping. Watch your inbox for the next edition of Access Point, where we’ll discuss how to identify clumping in the circuit.

AC infusion rate for TPE and RBCX
AC infusion rate (ACIR) is the rate at which ACD-A is infused to the patient. It is calculated as mL/min/L total blood volume (TBV). ACD-A contains citrate, so the AC infusion rate can also be thought of as a “citrate dose rate.”

Spectra Optia calculates the appropriate AC infusion rate based on the patient's TBV. See the examples below.

The default ACIR is 0.8 mL/min/L TBV. However, you can configure a range of 0.8 to 1.2 mL/min/L TBV. When configuring a starting ACIR higher than 0.8 mL/min/L TBV, it is important to remember that not all patients will be able to tolerate a higher rate.

The main run screen displays a current ACIR that may fluctuate during the procedure but will never exceed the configured value or the maximum value entered on the run values screen.

When performing a single-needle exchange (either TPE or RBCX), the current ACIR on the main run screen is an average of the draw and return cycles. Remember that the patient receives AC only during the return cycle in a single-needle procedure.

The ACIR can be increased above 1.2 mL/min/L TBV. However, the system will run in Caution status within a range of 1.3 to 2.5 mL/min/L TBV. Below is an example of the Caution status screens (as seen in software update version 12).


Adjusting for success
Understanding how to adjust inlet:AC and ACIR values during TPE and RBCX exchanges is an important skill to help you create successful outcomes for the procedure — and your patients. If you have questions or want to learn more, please email us at  or call 877.339.4228.

Terumo Blood and Cell Technologies. Anticoagulant Management on the Spectra Optia Apheresis System. Successions Training Presentation. 2021. Part number TS-OPTI-01182.
Terumo Blood and Cell Technologies. Concepts of Anticoagulant Management. Training Presentation. 2022. Part number TS-OPTI-01105.
Terumo Blood and Cell Technologies. Red Blood Cell Exchange (V12 RBCX) Rx Only Procedure Training (Including Single-Needle Option). 2023. Part number TS-OPTI-00799.
Terumo Blood and Cell Technologies. Therapeutic Plasma Exchange (TPE). Spectra Optia Apheresis System. Training Presentation. 2023. Part number TS-OPTI-01918.
Terumo Blood and Cell Technologies. Version 12 Software Updates. Spectra Optia Apheresis System. Training Presentation. 2020. Part number TS-OPTI-01243.

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