VenoVenous ECMO Initial Cannulation

VV ECMO can be done via several methods

1. Jugulo-femoral – as seen on this page for the femoral catheter and the IJ catheter insertion is coming soon
2. Femoral-femoral – not ideal but sometimes necessary. The technique will be the same as listed on this page for 2 catheters (1 of them will not be inserted as deeply)
3. Jugular-dual-lumen cannula (coming soon)

Let’s first discuss the Jugulo-femoral approach:

This page is guest-authored by John Greenwood; it originally appeared on the excellent MarylandCC Project Blog.

Initial Cannulation (2 Cannula Technique)

Step 1: Get your gear – Initial Set-Up & Preparation

• Quiet down the room.
• Prep the patient with full-barrier, sterile scrub & drapes.
• Heparinize the patient: 3,000 – 5,000 units (100 units/kg).
• Fill a large, sterile bowl with NS and have a 60 cc bulb syringe ready for cannula irrigation and flushing.
• Initial Vascular Access
  • Be efficient: While setting up the circuit and the team is gathering supplies, start by obtaining vascular access
  • Initial access: Place a right femoral CVC, left femoral a-line, and a right IJ CVC under ultrasound guidance.  If you already have an a-line, you can suture the arterial wire in place for future use.
  • Pitfall:  Not placing these lines under ultrasound guidance: As we all know, in the critically ill or critically hypoxic patient, arterial blood can look the same color as venous blood.  Don’t count on appearance alone.  Even using a pressure column can be misleading. 
  • Double-check: Confirm wire placement in the lumen of the vessel
• Cannulation Equipment
  • Cannulas
    • Venous Cannulas: Sizes range from 23 – 29 French steel wire reinforced
    • Arterial Cannulas: Sizes range from 19 – 21 French steel wire reinforced
    • Different insertion lengths: Range from 15 – 55 cm (depending on manufacturer)
    • Lock introducer
    • The size of the venous cannula directly determines blood flow.  The largest possible venous cannula should be used to maximize flow and easily achieve target output.
      • Some will choose cannula size on flow goals alone (See Cannula info)
      • Some data to suggest the use of US may be helpful to determine vessel lumen size and appropriate cannula size (Grasselli, 2010 PMID: 20872350)
    • Venous cannula length targets:
      • Femoral:  Distal tip rests in the IVC, generally at the level of T10 – T11.  You do not want to advance the cannula past the hepatic vein, as this can cause an obstruction and hepatic congestion.
      • Internal Jugular: Distal tip to rest in the SVC
      • Try to measure the lengths with the cannulas beforehand so when advancing you know when to stop!
    • Note: For venovenous ECMO, circuit of a femoral drainage (deoxygenated blood) and internal jugular return cannulas (oxygenated blood) believed to provide less recirculation than the reverse.
  • Dilators: Series of 8, 12, 16, 20, & 24 French dilators

  

Step 2: Dilate up the initial insertion sites

• Insert the 150 cm guide wire through the distal port of the femoral CVC.
• Remove the  CVC and hold pressure over the insertion site to prevent excessive bleeding.
• Load the 8 Fr dilator onto the introducer wire, & advance it just to the skin.
  • Prior to advancing the dilator you will have to extend your initial incision.
  • Extend the incision by about 1cm just smaller than the size of your dilator.
  • This will provide adequate hemostasis each time you dilate the soft tissue.
• Introduce the dilator in a corkscrew-wise fashion, advancing the dilator at the level closest to the skin
• As you advance the dilator, periodically check to make sure your guide wire freely moves within the dilator itself.  If you develop a kink or difficulty passing the dilator, you run the risk of lacerating the vessel. (GAME OVER)
• Repeat this step for each dilator up until you reach the appropriate size for your chosen cannula.

Step 3: Inserting the ECMO Cannula

• After your final dilation, load your introducer onto the 150 cm wire.
• Advance the introducer through the soft tissue, far enough that you actually dilate the wall of the femoral vein.
• Remove the introducer and hold lots of pressure.
• Load your venous cannula on to the introducer, then on to the 150 cm guide wire.
• Finally, advance your cannula to the pre-decided distance.
• Remove the dilator, wire, & double clamp the open end of the cannula.
• Flush your cannula with a copious amount of sterile saline.
• Pearl: There is a slight step-off between the cannula and the introducer due to the actual thickness of the wire-inforced cannula itself.  If your dilation is inadequate, this step off can get hung up on the soft tissue while attempting to insert it into the vessel.
• Pearl:  You can use your ultrasound to visualize cannula placement in the IVC!  Use it.

Step 4: Connect to the cannula to the circuit

• Check the circuit tubing: Remove all twists & coils.  Make sure that there is plenty of length between the circuit and the cannulas themselves.
• Irrigate the ends of the tubes:  As you attach the cannulas to the circuit tubing, use the bulb syringe to irrigate the ends to prevent air from getting trapped in the tubing

Step 5: The same steps above for the return cannula

Step 6: Turn on the circuit (we’ll add more about this in a separate post)

• Goal flow for VV ECMO (in adults) about 50-60 cc/kg/min.  You can start at around 2 liters and titrate up, usually to a goal of 4-5 liters per minute.
• Start the sweep at about 2 lpm (for CO2 clearance) and titrate.

Step 7: Clean up & confirmation

• Order a chest & abdominal XR to confirm cannula location
• While you are waiting, you can also perform a bedside ultrasound to visualize the cannula tip in the IVC.
• Make sure your cannulas are secure.  Usually, place at least 2 stabilizing sutures (for IJ’s) and 3-4 for the femoral cannulae with an 0 silk suture. Cover the sites with a sterile dressing.

Expect more from John in the coming months.

John Greenwood is an Emergency Medicine trained, Critical Care medicine fellow in the amazing city of Baltimore, MD. He is creator of the EMRA PressorDex and a founder of the MarylandCC Project. His particular interests include mechanical circulatory support & medical education. He is a proud supporter of #FOAMcc #FOAMed. Follow him on Twitter @JohnGreenwoodMD.