Singer and performance artist Laurie Anderson found herself locked in a hyperbaric oxygen chamber last week (ends11Jul14) during a routine therapy session in New York.

The O Superman hitmaker, 67, reportedly had to text a friend when she realised she couldn't exit the person-sized capsule, and the pal then called for help.

According to the New York Daily News, Lou Reed's widow had escaped the chamber by the time emergency service officials arrived at Pure Flow spa, and she declined medical treatment.

The spa's owner, Andrew Barile, told the publication that Anderson was in the chamber for about 45 minutes, adding, "There was a miscommunication on the timing."