The child may move or cry but will not remember the procedure. Often, EMLA or lidocaine are also used to ensure that the procedure is pain-free. A milky liquid given by IV, propofol has rapid onset with a rapid recovery. Propofol, a general anesthetic, will cause your child to lose consciousness. At low doses, propofol prevents memory of the procedure, but may not relieve all pain, so it is often used with EMLA or lidocaine.
Ketamine needs expert monitoring.
For these reasons, ketamine is no longer in wide use for pediatric sedation for procedures. Discuss with your oncologist and anesthesiologist which method will work best for your child. I think that one of our most important jobs is to advocate, strongly if necessary, for adequate pain control. If the dose doesn't work and the doctor just shrugs her shoulders, say you want a different dosage or drug used. If you encounter resistance, ask that an anesthesiologist be consulted.