Position: Supine
Time: 30-60 min (short)
Blood Loss: Low (10-50 ml)
Post-op Pain: Minimal (1-3)
Maintenance Paralytic: No
Lead: Yes

Approach – The type and length of procedure will dictate the exact choice of anesthetic, but these cases are (for the most part) performed under MAC. Several types of diagnostic angiograms exist (e.g. cerebral, vascular, coronary, etc.), which can contribute to decision on approach to take.

Preoperative Period – Communicate with the patient that they will be lightly sedated/awake for the procedure. In the event that a patient is highly anxious and/or uncooperative, a general anesthetic utilizing an LMA or ETT may be needed. Because your anesthesia station may be far from the IR table (limiting visual/direct access to the patient), instruct the patient to verbalize if they are feeling uncomfortable and would like more medication.

Surgeon Preferences – Ask the surgeon ahead of time what their preferences are for anesthesia. The anesthetic for these procedures can be tricky, as the surgeon will want the patient comfortable and immobile, but also able to follow commands if needed (e.g. for a breath hold, position change, etc.). If the patient is too deep and falls asleep, surgical stimulation can cause the patient to suddenly awaken and move, which is not appreciated by the surgeon.

For a short diagnostic procedure (less than 60 min) – a combination of a benzodiazepine and opioid can be used. When the patient enters the room, 0.5 – 1 mg of Versed can be given, followed by 25 – 50 mcg of Fentanyl just prior to the surgeon injecting local anesthetic around the access site (e.g. femoral/radial). The injection of local anesthetic followed by the sheath/catheter insertion is usually the most painful portion of the procedure. If the patient becomes uncomfortable after access is established, alternating doses of Versed (0.5 – 1mg) and Fentanyl (25 – 50 mcg) can be given to keep the patient comfortable.

For longer procedures (60 min or more) – a Remifentanil and Precedex infusion may be indicated. Remifentanil is a great medication for these procedures, as it helps to keep the patient immobile and is quickly metabolized after stopping the infusion. Patient requirements will vary, but a common starting point for these infusions is around 0.02 – 0.04 mcg/kg/min for Remifentanil and 0.5 mcg/kg/hr for Precedex. Some providers will give a small bolus (4-8 mcg) of Precedex at the beginning of the procedure to help the Precedex infusion set up faster. For MAC cases, Remifentanil is typically not titrated above 0.1 mcg/kg/min.

Room Setup – Your anesthesia machine will likely be 5 – 10 ft from the IR fluoroscopy table. The IR table moves up/down and a C-Arm will be moved into the surgical field. Space is limited, so for this reason organize your lines/tubes so that everything does not get caught or accidentally removed from the patient when the IR table or C-Arm is repositioned. Sometimes there are hooks on the side of the IR table for your lines to pass through so that nothing gets caught.

Pulse Oximetry – The surgeon will sometimes want pulse oximetry monitored at two separate sites. One on the same side where they establish vascular access (e.g. right radial access, place pulse ox on right finger) and the second on the opposite side as accessed (e.g. right radial access, place second pulse ox on left hand, or either a right or left toe). If they only want one pulse ox, it is usually on the same side as where they establish access (e.g. right femoral artery, place pulse ox on right toe). This is to monitor for adequate perfusion to the extremity accessed. Notify the surgeon if there is a sudden change in pulse oximetry.

Fluoroscopy / Xray (general considerations): Have lead aprons and thyroid shields available. Alternatively, distancing yourself 3 to 6 feet will reduce scatter radiation to 0.1% to 0.025% respectively. Occupational maximum exposure to radiation should be limited to a maximum average of 20 Sv (joules per kilogram – otherwise known as the Sievert/Sv) per year over a 5 year period. Limits should never exceed 50 Sv in a single year.

These procedures are usually performed in an interventional radiology suite utilizing fluoroscopy. The surgeon will likely access either the radial or femoral artery to introduce an arterial sheath/catheter/guide wire specific to the type of diagnostic procedure being performed. A local anesthetic is commonly injected around the site (e.g. femoral/radial) prior to arterial access.

Sometimes these procedures are strictly diagnostic in nature, but can also be paired with possible intervention dependent on the findings of the angiogram (e.g. vascular angiogram with possible balloon angioplasty). Be sure to research exactly what the goal of the angiogram is ahead of time, as it may dictate which type of anesthetic you prepare for. An example would be a case that begins as a diagnostic vascular angiogram of the lower extremities under MAC with a Remifentanil and Precedex gtt, but then has to be converted to a GETA due to the angiogram indicating the need for an open femoral popliteal bypass.