3.2 Apheresis Nursing Care: Vascular Access, Citrate Toxicity & Donor Safety

1. Apheresis Nursing Management & Vascular Access Care

Continuous mononuclear cell (MNC) leukapheresis processes large blood volumes (12 to 24 liters, equivalent to 2 to 4 total blood volumes) at rapid inlet flow rates (50 to 100 mL/min) over 3 to 5 hours.

Vascular Access Options

1. Peripheral Venous Access:
   • Preferred whenever possible to avoid surgical catheter complications.
   • Requires two large-bore peripheral veins (16-gauge to 18-gauge rigid fistula needles or specialized apheresis angiocatheters) in antecubital fossae.
   • One dedicated "draw / inlet" line and one dedicated "return" line.
2. Central Venous Apheresis Catheters (CVAC):
   • Required if peripheral veins are inadequate, small, fragile, or sclerosed from prior chemotherapy.
   • Catheter Specifications: Dual-lumen, high-flow (12 to 14 French), rigid-wall, non-collapsible catheters (e.g., Mahurkar, trialysis, or temporary tunneled apheresis lines) placed in the internal jugular or femoral vein.
   • Nursing safety alert: Use only vascular access validated for the required inlet/return flow and the apheresis device. Many standard PICCs or ports cannot support collection flow, but suitability depends on lumen, tip, device specifications, and institutional policy rather than a blanket contraindication.
   • Central access may contain heparin or citrate lock solution. Identify the catheter, prescribed lock concentration and lumen volume, then remove or manage the lock exactly as the device and institutional apheresis policy directs before connection; an unverified concentrated lock can cause systemic toxicity.

2. Anticoagulation & Citrate Toxicity Management Protocol

Leukapheresis requires continuous regional anticoagulation of the extracorporeal circuit using Acid Citrate Dextrose Solution A (ACD-A). Citrate prevents clotting inside the centrifuge bowl by chelating free divalent cations, primarily ionized calcium ($Ca^{2+}$) and magnesium ($Mg^{2+}$).

As anticoagulated blood returns to the patient, uncomplexed citrate enters the systemic circulation. Although the liver, kidneys, and skeletal muscle metabolize citrate into bicarbonate within minutes, the rapid infusion rate often overwhelms metabolic clearance, leading to acute systemic hypocalcemia and hypomagnesemia.

+--------------------------------------------------------------------------------------------------+
|                                 ACD-A CITRATE TOXICITY CASCADE                                   |
|                                                                                                  |
|   ACD-A Infusion into Circuit ---> Chelates Free Ionized Ca2+ ---> Blood Returned to Patient     |
|                                                                                 |                |
|                                                                                 v                |
|   Neuromuscular Irritability <--- Rapid Drop in Systemic Serum Ionized Ca2+ (<1.00 mmol/L)       |
|   * Perioral Numbness & Tingling                                                |                |
|   * Carpopedal Spasms & Tetany                                                  v                |
|   * Chvostek & Trousseau Signs                        Cardiac Electrophysiological Changes       |
|                                                       * QTc Interval Prolongation (>460-500 ms)  |
|                                                       * Ventricular Dysrhythmias & Arrest        |
+--------------------------------------------------------------------------------------------------+

Clinical Manifestations of Citrate Toxicity

• Early/mild: circumoral or fingertip paresthesia, metallic taste, nausea or lightheadedness.
• Progressive: tremor, muscle twitching/cramping, carpopedal spasm, hyperreflexia, chest symptoms or positive Chvostek/Trousseau signs.
• Severe: tetany, laryngospasm, seizure, hypotension, bradycardia, QT prolongation or ventricular dysrhythmia. Symptom severity and ionized calcium/magnesium guide the protocol response; no universal laboratory band defines every patient.

Citrate Toxicity Prevention and Nursing Response

Establish baseline symptoms and review calcium/magnesium, renal/hepatic function and arrhythmia risk as the program directs. Prophylactic oral or IV calcium, citrate ratio and processing rate are procedure-specific. During collection, ask about perioral/fingertip tingling, chills, nausea, cramping or chest symptoms and observe for tremor, tetany, hypotension or rhythm change.

For symptoms, slow or pause the procedure under protocol, notify the apheresis clinician, reassess vitals and give ordered calcium through a compatible route/rate. Severe symptoms require urgent ECG and electrolyte assessment and emergency support. Calcium chloride has greater extravasation injury risk than calcium gluconate and requires appropriate access and verification.

3. Donor Safety, Monitoring, and Adverse Event Management

Whether collecting from an autologous patient or a healthy allogeneic donor, mobilization and apheresis carry distinct clinical risks that require systematic nursing assessment.

Donor Education, Voluntariness, and Follow-up

A healthy donor receives no direct therapeutic benefit, so education and consent must remain donor-centered. Explain the collection choice, mobilizing medication schedule, expected bone pain/fatigue, apheresis duration, vascular-access possibilities, citrate symptoms, activity restrictions, and uncommon urgent symptoms in plain language. Confirm that donation is voluntary and that the donor can raise concerns or withdraw through the donor program without coercive family pressure. Review pregnancy/contraception precautions and medication restrictions as applicable, provide a 24-hour contact route, and arrange program-defined follow-up after collection. New left-upper-quadrant or shoulder pain, syncope, dyspnea, chest pain, neurologic symptoms, uncontrolled bleeding, or line-site infection requires prompt evaluation.

Medullary Bone Pain

• Incidence & Pathophysiology: Experienced by $>80%$ of donors receiving G-CSF. Caused by rapid granulocytic hyperplasia expanding within non-compliant bone marrow cavities (pelvis, sternum, ribs, spine, long bones).
• Nursing Management:
  • Use the program-approved analgesic plan after reviewing liver function, alcohol exposure, combination products and the patient-specific maximum daily acetaminophen dose.
  • An NSAID may be considered only if permitted by the donor/program plan after reviewing platelet count, bleeding risk, renal function, gastrointestinal risk, allergy and interacting medicines; do not convert a study-guide dose into an order.
  • Antihistamine Therapy: Some programs consider an antihistamine for growth-factor bone pain, but evidence is mixed and a precise mast-cell mechanism or guaranteed benefit is not established. Use only after medication review and an authorized plan.

Splenic Enlargement and Rupture Precautions

• Pathophysiology: G-CSF can cause a small, transient increase in spleen size during mobilization. Clinically palpable enlargement is not universal, and splenic rupture is rare.
• Life-Threatening Risk: Splenic rupture is a rare but fatal complication of G-CSF mobilization.
• Patient Education & Nursing Interventions:
  • Teach the donor program’s activity restrictions. Avoid contact/high-impact activity and other abdominal trauma during mobilization and for the program-defined recovery interval; do not substitute one lifting limit or duration for the actual donor instructions.
  • Educate donors to seek immediate emergency care for left upper quadrant (LUQ) abdominal pain, left side flank pain, nausea, vomiting, dizziness, syncope, or referred left shoulder pain (Kehr's sign) caused by diaphragmatic irritation from subcapsular splenic hematoma.

Hematologic Depletion Post-Apheresis

• Thrombocytopenia: Centrifugal leukapheresis also removes platelets, and the decline varies with baseline count, device, processed volume and repeated collections. Check counts at the program-defined intervals and apply its threshold for another collection; evaluate bleeding or unexpectedly severe cytopenia promptly.
• Vasovagal Reactions & Hypovolemia: Rapid shifts in extracorporeal volume ($200\text{--}400\text{ mL}$) can induce vasovagal syncope or orthostatic hypotension. Maintain normovolemia with IV saline boluses as needed.