Older patients could have their risk of dying during and after open heart surgery reduced and precious donated blood could be conserved after new research has found not as much blood is needed when carrying out heart surgery on older patients.

An international study of 5200 patients worldwide, including 560 Kiwi patients, contradicts previous best practice internationally of transfusing large amounts of blood to patients aged over 75 undergoing cardiac surgery.

Auckland Hospital Intensive Care specialist Dr. Shay McGuinness, a lead investigator in the study, said the latest study followed patients six months after they had surgery and found using less transfused blood during and after heart surgery lowered the patient's subsequent risk of heart attack, stroke, kidney failure, and death.

"Before this study, it was accepted wisdom that older patients need to be transfused to a higher hemoglobin level because it was thought their body's physiology and ability to cope with the stresses of surgery made them less able to tolerate lower levels than younger patients," McGuinness said.

The study, published in the New England Journal of Medicine, was the largest ever transfusion trial in cardiac surgery to be carried out. Auckland City, Waikato, Wellington, Christchurch and Dunedin hospitals were among the 74 hospitals to be involved in the trial, and New Zealand had the second highest number of patients involved in the trial.

Blood Transfusions

Study co-author Dr. Paul Young, from Wellington's Medical Research Institute of New Zealand (MRINZ), said the study would change how much blood needed to be given during and after cardiac surgery.

"This means many who would have been transfused in the past will no longer require it at all, and patients who previously required several units of blood may now only require one," said Young.

NZ Blood Service spokesperson and transfusion medicine specialist Dr. Richard Charlewood said the new study would significantly reduce the amount of donated blood required for transfusions.

"As our population ages and we do more and more cardiac surgery on a growing number of older patients, a reduction in the use of blood may help to ease the pressure on both donors and the blood service, where donors are finding it difficult to make time to donate."