BOWNES, Senior Circuit Judge The main issue on this appeal requires us to determine under Massachusetts law the duty to warn imposed on the manufacturer-seller of medical devices used during open-heart surgery and the closely related question of causation. Plaintiffs-appellees Mark Knowlton and his mother, Bonnie B. Tetrault, brought suit for injuries from chemical burns incurred by Knowlton during open-heart surgery at Children's Hospital in Boston. The jury found that defendant-appellant Deseret Medical, Inc. was liable for failing to adequately warn the surgeon-user of the danger involved in the manner in which the surgeon used the devices. I. BACKGROUND
