A safer way of imaging blood vessels during surgery

MONTREAL – A new medical device at the Jewish General Hospital, the first of its kind to be used in Canada, is boosting the safety of capturing images of the blood vessels of certain patients during vascular surgery.

The technology, known as the Angiodroid, enables an x-ray technologist to inject a specific volume of carbon dioxide (CO2) at a precise rate into the patient’s vascular system. This helps to more safely produce an image of the area in the body where a surgical procedure – such as unblocking a blood vessel or applying a stent – will be performed.

The device, which stands a little over a metre tall, resembles a grayish-white column on wheels, topped with its own screen and controls. Positioned near the patient in the operating room, it transfers CO2 from a tank to the patient in an amount and at a rate determined by the surgeon.

A key feature is that the Angiodroid automatically flushes the CO2 line before use. This removes the risk that an air bubble will be inadvertently injected into the patient along with the CO2, says Dr. Elie Girsowicz, a vascular surgeon, who is director of the Vascular Surgery Residency Program and an Assistant Professor at McGill University.

Currently, an x-ray technologist or vascular surgeon injects an iodine-based contrast dye into the vascular system of most patients during surgery to make the blood vessels easily visible in an angiogram (a type of x-ray).

In most cases, Dr. Girsowicz explains, there are no reported problems using contrast dyes for angiograms. However, in rare instances, kidney problems can result from the use of certain contrast dyes — a disorder known as contrast-induced nephropathy.

Although this toxicity can develop only in about 2 percent of those who receive the dye, the risk is higher among people who have diabetes or a history of heart disease, blood diseases or chronic kidney disease. In people with advanced kidney disease, the risk can soar to 30 or 40 percent.

So far, the only alternative has been to inject CO2 manually into the patient, even though the manual element causes the volume and flow-rate of the gas to be inexact, while making the intrusion of other gases possible. A further drawback is that the quality of the resulting image is less than optimal.

The Angiodroid eliminates these problems and opens the way for CO2 to be more widely used, says Lusine Arutyunyan, a JGH biomedical engineer in charge of the hybrid operating room (encompassing surgery and medical imaging), where the Angiodroid is used.

She notes that in the manual use of CO2, patients may experience pain if the gas is injected too quickly or with too much pressure. However, since the Angiodroid allows the technologist to fine-tune the injection process, the discomfort is eliminated or minimized.

Ms. Arutyunyan says that since the device is automated, the surgeon can also store the settings in the machine’s memory, enabling exactly the same procedure to be repeated, if necessary.

According to Dr. Girsowicz, surgeons in some other countries are so happy with the results that their hospitals have significantly reduced their use of iodine and have arranged for the Angiodroid to administer CO2 to most of their patients.

“We’re not there yet,” he said, “but I think we’re now in a position to begin going through a slow period of transition. It’s a great opportunity for our patients, who will benefit from the added safety and precision.”