Aplastic Phase
Patient remains in isolation until the stem cells have engrafted and peripheral blood neutrophils recover. Usually this means a stable neutrophil count >0.5 x 109/L on serial complete blood counts for 2-3 days.
Time for neutrophil recovery following transplant is largely dependent upon graft type. On average :-
- Peripheral blood HSCT engrafts 7-12 days
- Bone marrow HSCT engrafts 10-16 days
- Umbilical cord HSCT engrafts 14-28 days
Before neutrophil engraftment patient is at highest risk for complications either directly due to the toxicity of the conditioning regimen or from the severe complications of having an aplastic marrow (Early Complications of HSCT).
Supportive care and empirical antibiotic therapy are very important during this phase.
Early in this period, infection is a significant risk:
- Herpes simplex virus (HSV) usually from reactivation of a previous infection
- Endogenous flora, such as skin and gut organisms most frequent sources of infection
- Hospital-acquired nosocomial infections (may be antibiotic resistant)
- Fungal infections
Oral intake is usually severely reduced because of the severe mucositis that most patients develop. Total parenteral nutrition may be necessary.
Multiple blood and platelet transfusions are often required during the aplastic phase.
Hemoglobin and platelets on average take longer to stably engraft compared to white cells (in some patients may take months or remain incomplete). Occasionally patients may require long-term blood and platelet transfusions months after the transplant.
Most patients remain in the hospital for 4 to 8-weeks after a transplant. Patients with serious complications may remain in hospital for months.
Engraftment phase
Immediately after the aplastic phase, the stem cells start to engraft in the bone marrow and immune function starts to recover together with the blood counts.
During this period (several weeks) health problems include:
- Viral infections (especially CMV).
- Acute GVHD
- GVHD can also act "against" the leukemic cells and cause "graft versus leukemic" (GVL) effect and this helps to control the underlying leukemia
- Venoocclusive disease (VOD)
- Weight gain
- Platelet transfusion refractoriness
- Hyperbilirubinemia
- Damage to the liver with the deposition of thrombotic elements throughout the liver microcirculation.
- Supportive care and careful fluid management most important.
