The ornamental design for a medical pumpholder, as shown and described.
FIG. 1 is a top view of the design for a medical pump holder.
FIG. 2 is a front view thereof.
FIG. 3 is a bottom view thereof.
FIG. 4 is a right side view thereof.
FIG. 5 is a rear view thereof.
FIG. 6 is a left side view thereof; and,
FIG. 7 is a perspective view thereof.
The broken line showing of parts of the drawings is included for the purpose of illustrating use and environment and forms no part of the claimed design.