A drug used to counter the effects of the heart lung machine can produce small, but hazardous, changes in blood pressure.

Without the heart lung machine, heart bypass surgery would not be possible. But the patient has to be given the anticoagulant drug heparin to stop clots forming in the machine while it takes over the heart's job during the operation. It's standard to reverse the effects of heparin with another drug called protamine.

It has long been known that up to five per cent of patients suffer a severe, potentially fatal, allergic reaction to protamine. Now researchers at Duke University Medical Center reveal that the protamine problem might be more widespread than previously thought.

They measured fluctuations in blood pressure in the 30 minutes after protamine administration in a group of 6,921 people undergoing bypass surgery. Even small fluctuations appeared to be linked with a higher risk of in-hospital death after surgery. The researchers don't advocate stopping the use of protamine - for the risk is outweighed by the benefits of bypass surgery. But they advocate that research for an alternative should be intensified.

Source

International Anaesthesia Research Society Meeting 25th March 2003