News in Science

Expanding foam could stop internal bleeding

Life saver US researchers have developed a spray foam that can be injected into a wounded soldier's abdominal cavity to help stop internal bleeding.

When soldiers are wounded on the battlefield, getting them to advanced-level treatment facilities within the first 60 minutes of injury often makes the difference between life and death.

During this 'golden hour', internal bleeding - particularly in the abdominal cavity - is life-threatening because there is little that can be done to stop the bleeding. Internal wounds can't be compressed like external wounds, nor can they be treated with tourniquets and haemostatic dressings, which require a medic to access to the injury in order to dress it.

A team of researchers at the Defense Advanced Research Projects Agency (DARPA) hopes their new foam can help the wounded survive until they get to treatment facilities.

The polyurethane polymer foam can be injected by a field medic in two liquid phases, a polyol phase and an isocyanate phase. When the liquids mix, they expand to 30 times their original volume.

As it expands, the foam fills the abdominal cavity and conforms to the surface of the injured tissue and organs. The foam then hardens, providing resistance to intra-abdominal blood loss. DARPA says the foam can even expand through pooled and clotted blood.

During tests, removal of the foam took less than one minute after an incision by a surgeon. Only minimal amounts of the foam remained in the abdominal cavity and no significant amount of tissue stuck to the foam.

No human tests have been conducted yet. However, tests on pigs did show that the foam raised survival rates for liver injuries after three hours from eight to 72 per cent and reduced blood loss by six fold.

The foam is set to undergo Phase II trials in the hope of future FDA approval of a prototype device.