Haemostat device eliminates risk of embolism

UK company invents powder dispenser that can stop blood vessels from bleeding but does not inject air into wound

Team Consulting, the Cambridge-based medical device design and development agency that came up with the original design for the life-saving Epi-pen, has developed the Convesaid device, which allows surgeons to spray opened blood vessels with a powdered substance that stops bleeding during an operation without any risk of introducing air into the blood vessel, which could cause a life-threatening embolism.

The handheld device, which is disposable, is currently at a functional proof of principle stage, and the agency hopes it will serve as a shop window for its expertise.

The Convesaid device in use

According to the British Medical Council, 30 per cent of specialist inpatient surgeries involved a bleed during the process which increased the length of hospital stay. Current devices to stop bleeding, which dispense substances known as haemostat powders, tend to entrain the powder within a stream of air. However, using these carries a risk of squirting air into an open blood vessel.

The Convesaid device is designed to be intrinsically safe, and the design team, led by head of MedTech Ben Wicks, employed a little-known principle of physics to ensure its safety. Called the Coanda effect, this states that a stream of gas will tend to follow an adjacent curved surface.

A return channel in the device nozzle uses the Coanda effect to return air to the pump, confining it inside the casing

Like other sprays, the device contains a battery powered pump to create a stream of air which entrains particles of haemostat powder from a reservoir attached to the back of the device. The powder-laden air stream is sent down the long nozzle of the device. At the tip of the nozzle, however, the channel down which the stream flows splits into two, with a smooth curve leading into a separate return channel back along the nozzle and back to the pump. The powder, meanwhile, is propelled out of the tip and onto its target “It’s almost like magic,” Wicks comments. “It looks like there must be air coming out of the device, but there isn’t.” The tip can even be placed directly onto the wound without any risk of embolism.

As the design evolved in consultation with surgeons, the team introduced failsafe features such as a trigger that cannot be operated until the pump is turned on. “Convesaid gives surgeons the ability to stop a variety of bleeds in a rapid, accurate and safe way. It takes no time to set-up and is unencumbered by any air lines. Convesaid will give haemostat manufacturers the ability to deliver haemostats more effectively, more conveniently and, above all, more safely than ever before.”

Watch this video to find out more about Team Consulting and how Convesaid was designed: