After a subject signs our consent form, the next step of the study is placing a small (22 G) catheter in the artery of one wrist. This is done using local anesthesia to minimize the discomfort. Subjects will then have pulse oximeters attached to their fingers, occasionally other parts of the body depending on the type of device. These are attached as a small clip or band aid that goes over the nail bed. These instruments shine a light through the finger. Attachment and removal involves no discomfort. Next, the subject will have a nose clip placed on either side of their nostrils, so that they are forced to breathe through their mouth. The subject will then breathe a special gas mixture through a mouthpiece. (The mouthpiece is similar to what is used on a snorkel.)

Subjects will be asked to breathe regularly, but more deeply and somewhat faster than normal as the gas mixture is adjusted to lower their levels of oxygen. Blood samples are removed from the catheter in the artery at various time points. This does not involve further invasive procedures. Each typical “run” involves 12-13 samples, takes about 15 minutes, and finishes when the subject breathes oxygen. A complete study consists of 2-3 “runs” for a total of 25 samples (can be upwards of 35 samples, depending on what the sponsor study requires). The catheter in the wrist is then removed at the end of the study, and pressure is applied to the puncture site for 10 minutes. Subjects are then free to leave. Normal activities are fine, but vigorous activity of the arm where the catheter was placed should be avoided for several hours.