An intensive care specialist at Wellington hospital says the speedy evacuation of some hospital patients from Christchurch following the earthquake of 22 February was unprecedented.
Officials decided about four hours after the quake to move six patients initially.
Wellington clinical support services director Peter Hicks says they did not know what demands would confront the Christchurch emergency department that evening and decided to help reduce its workload.
"We collectively decided we needed to get everybody out of Christchurch as fast as possible because we had absolutely no idea what was coming next overnight," said Mr Hicks.
Flight teams took patients to Wellington, Waikato and Hastings and he cannot recall anything like it happening before.
"The closest we got previously was over several days quite a few years ago during some industrial action in Christchurch," said Mr Hicks.
Overall, 100 patients were eventually evacuated.
Seven resthomes were so badly damaged they had to be evacuated, two were partially evacuated and a further 10 have serious infrastructure problems.
Some 600 rest home beds have been lost and more than 500 elderly people have had to be moved.
About half were sent elsewhere in Christchurch or Canterbury; 52 to Dunedin; 50 to Nelson; 45 to Auckland; four to Hamilton and 21 to Wellington.