TOOLS OF THE TRADE

The history behind the instruments used by doctors. This week: Cannula A CANNULA is a thin, flexible tube, usually made of plastic, used to drain fluid from the body, or to deliver medication or oxygen.

The creation of this nowubiquitous piece of medical equipment is attributed to the architect Sir Christopher Wren, who in 1657 documented the first successful use of such a device — the original was made from a pig’s bladder and quill — in a letter to an acquaintance.

But some modern journals note the use of similar devices from even earlier, with scientists at the University of Rome suggesting they may have been in use for tracheostomies, where a tube is inserted into the throat to help with breathing, from the Middle Ages.

These days, the device is usually inserted into a vein or artery. Some cannulas can be attached nasally, for the delivery of oxygen.