Science Daily report that cell phones should be kept at least 1 metre distant from hospital beds and equipment :

Dr Erik van Lieshout, lead researcher from the Academic Medical
Center, University of Amsterdam, said; "Our work has real implications
for present hospital restrictions of mobile phone use in patient
areas."

"It is unlikely that mobile phone induced EMI in
hospitals will be eradicated in the near future so the one meter rule
currently in place should continue, as it is relatively safe,"
commented Dr van Lieshout.