Living the Scientific Life (Scientist, Interrupted)

tags: green blood, medicine

It was the middle of the night when surgeons were preparing to perform emergency surgery in Vancouver, Canada. The man they were going to operate on had developed compartment syndrome in his legs after he fell asleep while kneeling. Compartment syndrome is a dangerous medical condition where pressure builds up in the deep muscle tissues and can cause permanent nerve damage. However, when the surgical team established an arterial line in the man's wrist, they were surprised to discover that his blood was dark green instead of bright red. Even though the man is not a vulcan, it was like something out of Star Trek.

"During insertion, we normally see arterial blood come out. That's how we know we're in the right place. And normally that blood is bright red, as you would expect in an artery," said Dr. Alana Flexman from Vancouver's St. Paul's Hospital. "But in his case, the blood kept coming back as dark green instead of bright red."

"It was sort of a green-black. ... Like an avocado skin maybe," she added.

Samples were collected and the lab ruled out a dangerous condition called methemoglobin, where the blood's hemoglobin can't bind oxygen. Later, the lab diagnosed sulfhaemoglobinaemia, a condition that occurs when sulfur is incorporated into the oxygen-carrying hemoglobin in red blood cells. Sulfur causes the blood to turn green when exposed to oxygen. The condition is thought to be triggered by certain medications.

What caused this remarkable occurrence? Flexman and her colleagues think the green blood may have been caused by the man's migraine medication, sumatriptan, which he was taking in larger-than-recommended doasges of at least 200 milligrams per day. Sulfhaemoglobinaemia generally resolves with red blood cell turnover, although transfusion can be necessary in severe cases.

"The patient recovered uneventfully and stopped talking sumatriptan after discharge," said Flexman. She also mentioned that five weeks after his last dose of sumatriptan, there was no trace of sulfhemoglobin remaining in his blood.

Mr. Spock, of the starship Enterprise, had green blood because the oxygen-carrying ion in Vulcan blood is copper, not iron, as it is in humans.

Cited story.