Prior to entering the Bone Marrow Transplant Unit, your child will require the insertion of a special intravenous catheter. In addition, he or she may require one or more of the following:
- Collection of peripheral blood bone marrow stem cells (PBSC), which is required for cancers such as lymphoma, neuroblastoma, sarcomas, primitive neuroectodermal tumors (PNET) and Wilms' tumor
- Bone marrow stem cell harvest, which is required when a PBSC collection is not possible or is inadequate
- Busulfan pharmacokinetic study, which is required if your child will be receiving busulfan as part of the conditioning regimen.
The central venous catheters are special types of intravenous lines (IVs), central venous catheter that remain in place throughout the entire transplant process and help avoid the pain and discomfort of multiple IVs and blood draws. Through these catheters, chemotherapy, medications, blood products and nutritional support will be administered. These special IVs also are used for blood drawing.
The catheter is inserted in the operating room. Some children already may have had this operation in order to facilitate treatment of their disease. While under general anesthesia, the catheters are inserted into major blood vessels in the neck and exit the skin on the front of the chest or abdomen. A total of two catheters — one double lumen or two single lumen — are most often necessary. The procedure usually does not require hospitalization.
Parents and children, depending on their age, will be taught how to care for the catheters and change the dressings. The catheters typically remain in place for three to 12 months after the transplant.
Peripheral Blood Stem Cell (PBSC) Collection
When this procedure is done for an autologous transplant, it occurs following a course of chemotherapy when the marrow and cell counts are recovering. A drug called granulocyte colony stimulating factor (G-CSF) is administered daily to the patient by injections under the skin beginning three days after the chemotherapy has been given.
The patient will need daily blood and platelet counts to determine the timing of the special procedure called leukapheresis. During leukapheresis, blood is removed from the patient and passed through a special machine which collects those white cells that contain the bone marrow stem cells that are present in the blood. The remaining blood is returned to the patient. The procedure is done as an outpatient and takes four to five hours.
Depending on the number of stem cells collected, more than one leukapheresis may need to be done. Also, the leukapheresis may require the placement of a special catheter (femoral line) on the day of or prior to the procedure, which is done in the Pediatric Cardiac Catheterization Laboratory. The placement of the catheter can sometimes is done in the Operating Room under general anesthesia or in the Radiology Department under local anesthesia.
Bone Marrow Harvest
Bone marrow may be obtained from the patient for transplantation for solid tumors or as a back up to a T cell depleted marrow from a parent. While the patient is asleep under general anesthesia, multiple marrow aspirations are obtained from the pelvic bones along the lower back. The collected marrow is taken to the Pediatric BMT Laboratory for further processing and storage. The back-up marrow will be used in the event that the parental stem cell transplant fails to engraft.
If possible, the collection of the back-up marrow, catheter insertion and any other necessary surgical procedures will be done under the same anesthetic.
Busulfan Pharmacokinetic Study
If your child is going to receive busulfan as part of the conditioning regimen, a pharmacokinetic study will be done either prior to admission for transplant or with the first dose of the drug. Busulfan is a chemotherapy drug that in the past could only be taken by mouth as a pill Currently, an intravenous preparation of busulfan is available, which we are now using.
It is known that the amount of busulfan that gets absorbed into the blood stream and excreted by the body — called the effective drug — varies from one child to the next. By measuring the pharmacokinetics of a small test dose of busulfan or possibly even the first full dose of the drug, the precise total dose of the drug can be determined for each child in order to optimize the amount that gets into the blood stream while minimizing toxicity. If the pharmacokinetic study is done as an outpatient several days prior to admission for transplant, it will occur in the Pediatric Clinical Research Center (PCRC). If it is done on the first full busulfan dose, then it will occur in the BMT room. The attending physician will discuss the pharmacokinetic study in more detail at the informed consent conference.