Doctors treating the victims of the New Zealand volcano

Doctors treating the victims of the New Zealand volcano are importing skin to treat those burned in the eruption.

It is part of the intense medical response to treat those caught up in the disaster.

When someone has a burn injury, skin is used as a "natural plaster" to help healing. It helps stop infections and reduces scarring and pain.

Doctors take skin from another part of the body, such as the thigh or behind the ear, but donated skin is used if that is not possible.

Who are the White Island victims?As it happened: Details emerge of eruptionCan we predict volcanic eruptions?

It is donated after death, like other organs, and can be banked for several years.

Burns units keep a supply of donor skin - enough to cope with the normal needs of their patients.

But the White Island eruption is an extreme situation.

Medical authorities in New Zealand say they are currently caring for 29 patients in intensive care and burns units at four hospitals in Middlemore, Waikato, Hutt Valley and Christchurch.

Twenty-two are in a critical condition because of the severity of their burns.

One Australian patient is being transported home by air ambulance, with others set to follow over the next 24-48 hours so they can be cared for nearer their families.

Local media has reported only five to 10 people donate skin in New Zealand each year.

And since each adult has about two sq m (22 sq ft) of skin, doctors have requested 120 sq m (1,300 sq ft) of skin from the US, where there are more tissue banks.

An initial skin graft normally lasts a couple of weeks. The idea is the body can begin to repair itself, but replacement grafts are often needed.