A brief story of a series of events that represented some significant challenges for this perfusionist as well as the entire open heart and surgical ICU teams…
A Level 1 Trauma
Pager goes off- that’s never good. A call from the OR desk- Something going on in a chest- undefined trauma- we need you to come in. I shake off that deep REM sleep that leaves you groggy and punch drunk when you are so suddenly slashed away from it.
I call the surgeon to figure out what was going on, and the news is pretty much what you would expect this early in the morning. It involved the aorta, which was transected as a result of a MVA that left a young patient severely injured, multiple broken bones, major organ contusions, and a possible hemothorax.
The surgeon expressed his desire to attempt the aortic repair using left heart bypass (LHB) to minimize anticoagulation thresholds we would need to engage in standard CardioPulmonary Bypass (CPB). As well, LHB would allow for distal preservation of blood Q to the lower spine, splanchnic regions, and distal limb perfusion.
The unknowns that needed to be addressed were how we would deal with massive blood loss, poor pulmonary function, monitor the right femoral arterial pressure in tandem with a left radial arterial pressure to be able to assess and control blood flow in an effort to balance the intricacies of supplying enough distal flow to mitigate ischemic damage while at the same time keeping enough blood in the heart to allow for upper body perfusion and prevent atrial fibrillation in the event the heart was empty. This is why the two arterial lines were so important. The left radial would obviously need to be pulsatile- while the right femoral would be a non-pulsatile flow due to a X-clamp being applied to the descending Aorta. It ends up being a sublime balancing act to adequately protect the patient, therefore a more challenging case for the perfusionist.
Other considerations were:
- The patient’s age (young), the patient size (very low weight- basically a young juvenile in terms of size).
- Unknown damage to major organs yet to be determined
- Pulmonary issues: Hemothorax?
- Potential spinal cord damage
- Splanchnic perfusion
- How to approach the case
- Do you commit to LHB only and devise a very simple circuit (basically a shunt with a centrifugal pump driving flow),
- Or do you game plan for a possible conversion to standard CPB with an oxygenator in line, and the ability to recover what was going to be certain major blood loss?
That was discussed with the surgeon as well, and I told him I would modify the circuit so that we could start out as LHB only, and if needed- convert seamlessly to an inline oxygenator and traditional CPB.
Circuit modification was next on the agenda- I knew whatever I was going to do- it would be to the ECC on the HLM. I wanted to reduce the venous line to 3/8 tubing due to the low KG weight of the patient. We had a custom 3/8 line available- but there was no way to pre-prime it and make sure it worked in a LHB circuit. So then I shifted gears and decided to use the custom tubing pack we used for our ECMO circuits. It was perfect because it was tubing only- with no Oxygenator or centrifugal cut in to it. But it was a totally primable circuit.
I decided to cut the LHB outflow tubing into the line going from the reservoir to the centrifugal on our ECC by using a 3/8 Y connector. I did the same on the out flow tract of the centrifugal pump therefore bypassing the Oxygenator completely. It was a hard prime- deairing wasn’t easy- but I got it done. Essentially I Had two completely independent circuits setup- using a common centrifugal pump.
We have a sternotomy and control of bleeding. The plan is to heparinize to an ACT <300 seconds, stay warm, beating heart, go on LHB, and do the repair. I asked anesthesia if the patient’s lungs would provide adequate oxygenation during LHB and was assured that they would. WE heparinize, cannulate and….
I look at my HLM and what do I see? Absolutely nothing! The primary monitor screen had silently gone blank. Completely flat gray- nothing, no numbers- no touch screen controls- just blank. I informed the entire room we had a partially functioning HLM. The suckers and centrifugal and cardioplegia pumps were working and I was getting analog data (RPM, LPM etc.), so the pumps worked, but the brains of the HLM were unavailable.
Normally I would have changed out the HLM and gotten a new circuit together- but this was an emergency, the lines were connected, and the circuit modifications would make any changeout nearly impossible. So I went into reflex mode and rebooted the HLM. It worked! I got my monitor back, re-zeroed the transducers, but this particular HLM requires calibration of an internal O2 sensor that takes about 2 minutes with no gas flow- so I opted out of that requirement because of the situational time constraints we were facing- time to go on LHB and save the patient’s life.
Going on LHB with no monitoring (no right femoral art line, no left radial art line dude to interrupted flow, and cerebral saturations reading out) was about the same as driving you car through a tunnel without headlights, and pushing on the gas pedal not knowing how fast you are going. Upon initiation my flows were horrible, very poor venous return due to patient size and cannulation restrictions. The blood was very dark as well and getting darker. It became clear that the lungs could not keep up. Simultaneously we were losing quite a bit of volume to the cell saver- so I set up the ATS transfusion bag to hook up to our prime line on the LHB circuit and was able to add volume back to the circuit. All of this was happening very quickly, the EKG was demonstrating ischemic changes, complexes were widening and the blood was black. I told the surgeon the patient was dying, anesthesia stated the heart had stopped beating, and I started passing up lines for the ECC to get ready to transition to full CPB.
That wasn’t as seamless as I wanted it to be, but we cut in our ECC to the LHB circuit and successfully transitioned to full CPB and ultimately arrested the heart. During this part of the run I also had to figure out how to get all the blood out of the now discarded LHB circuit and return it to the patient’s circulation. It wasn’t pretty but I settled on connecting the 3/8 line to a 3/8 port on top of the reservoir and gravity draining the blood back into play. I had to get this done fairly quickly so the blood wouldn’t clot in the LHB circuit.
The repair really didn’t take that long and we were able to oxygenate appropriately and ultimately weaned the patient off CPB. After a couple of hours of attaining hemostasis and getting all the bleeding stopped, the patient was successfully transferred to SICU.
An hour after I got back to bed- the phone rang again…
Time for ECMO– the lungs needed a break.
To Be Continued…
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