15.4 Mechanical Circulatory Support
Key Takeaways
- IABP support is 1:1 timing with a helium balloon; consoles have altitude compensation—know your device and never let the balloon sit idle.
- Late inflation or late deflation are timing errors; a falling assisted diastolic bump is lost augmentation, not a reason to ignore the waveform.
- Impella and durable VAD transport is a power, flow, suction, and anticoagulation problem; suction usually means empty, malpositioned, or right-ventricular failure.
- VA ECMO supports heart and lungs; VV ECMO supports lungs only. Circuit chatter is often hypovolemia; emergency clamp is a trained-partner skill.
- Secure the console, confirm the inverter and helium supply, and fly only to a receiving team that already runs the device.
Mechanical circulatory support (MCS) is a moving pump you did not implant and must not drop. Domain 4.B.5 of the August 2026 Board of Certification for Emergency Nursing (BCEN) Certified Flight Registered Nurse (CFRN) outline tests mechanical circulatory support as transport principles—timing, power, gas, clotting, and destination—not as a secret list of required brand names. Do not memorize a BCEN device catalog that does not exist. Know how the balloon, axial pump, and membrane circuit fail in a climbing cabin, and refuse a receiving hospital that cannot run the machine.
Intra-aortic balloon pump: timing, helium, and altitude
An intra-aortic balloon pump (IABP) inflates in the descending aorta at the start of diastole and deflates just before systole. Inflation raises coronary perfusion (the diastolic augmentation bump). Deflation drops afterload so the next beat ejects easier. The sickest patients run 1:1 (every beat). Weaning uses 1:2 or 1:3. The shuttle gas is helium because it is low-density enough to keep up with a pulse.
Altitude compensation and the idle balloon
Boyle's law expands helium as cabin altitude rises. Modern IABP consoles have altitude compensation that automatically adjusts balloon volume. That is not a reason to ignore the device: know your console, watch the helium alarm, and confirm compensation is on before climb. An older or unfamiliar unit may need a manual change. Never fill the balloon with oxygen or air. Check the helium tank on the ramp.
Never let the balloon sit idle for a long stretch. A static balloon is a clot factory in the aorta. If the console fails, program teaching is to inflate and deflate the balloon manually on a short clock (many services use every few minutes) or to get the balloon out. Do not power the console down for a quiet cabin.
Augmentation versus timing errors
Read the arterial waveform, not the marketing sticker.
| Problem | What you see | Why it matters |
|---|---|---|
| Good 1:1 augmentation | Diastolic bump above unassisted systole; assisted end-diastolic pressure lower than unassisted | Coronary fill plus afterload reduction |
| Late inflation | Bump starts after the dicrotic notch | Missed coronary perfusion |
| Early inflation | Inflation during late systole | Ventricle ejects into an inflating balloon |
| Late deflation | Balloon still up at the next systole | Worst afterload spike |
| Early deflation | Assisted end-diastolic drop too soon | Lost afterload reduction |
Fix timing on the console; do not “treat” a late-deflation crash with another liter. Severe aortic regurgitation and acute dissection are classic reasons not to place a balloon—the balloon worsens regurgitation and can extend a tear. If you inherit one, talk to the receiving surgeon before you climb through a fresh Type A.
Impella, durable VADs, and suction
An Impella is a micro-axial pump sitting across the aortic valve (left-sided devices) or in the right heart (Impella RP). The console shows a P-level, flow in liters per minute, a placement signal, and a purge pressure. A durable ventricular assist device (VAD) you will actually fly is often a continuous-flow pump already sewn in. Principles overlap: power, flow, suction, and anticoagulation.
Suction events mean the inlet is starving—hypovolemia, the cannula against a wall, tamponade, or a failing right ventricle (RV) that is not filling the left pump. Do not answer suction by blindly raising the P-level or VAD speed; that worsens collapse. Drop the support level, look for volume or obstruction, check the placement signal, and treat the RV. Purge and systemic anticoagulation stay on per sending protocol; do not “hold all heparin for flight” unless the program and the receiving MCS team jointly own a bleeding crisis.
Power is the flight-killer. Confirm the aircraft inverter will run the console, know the battery minutes if the inverter drops, and never pull both VAD batteries at once. Secure the console so it cannot become a projectile. Do not kink the Impella catheter or driveline against a litter rail.
ECMO: VA versus VV, chatter, and the clamp
Extracorporeal membrane oxygenation (ECMO) is a trained-team circuit, not a solo-nurse gadget. Venoarterial (VA) ECMO drains vein and returns to artery: it supports the heart and the lungs. Venovenous (VV) ECMO drains vein and returns to vein: it supports lungs only, and the native heart must still circulate. Hypoxia on VV is often recirculation, a failing membrane, a pneumothorax, or cardiac output that outruns circuit flow—not a reason to crank ventilator fraction of inspired oxygen (FiO2) and ignore the blender.
Circuit chatter is violent shaking of the drainage limb from excessively negative inlet pressure: hypovolemia, a kink, coughing, or cannula malposition. Give volume if the tank is empty, unkink the line, and tell the specialist before you “fix” it with a random clamp. Emergency clamp is for catastrophic air or a broken circuit—come off ECMO and support the patient with a bag and drugs. That is a trained-partner move. Do not fly ECMO without the specialist your program requires.
- Confirm 1:1 IABP timing, helium supply, and altitude compensation; never idle the balloon.
- Treat Impella or VAD suction as empty, malpositioned, or RV-failed—not as a speed contest.
- Know VA (heart and lung) versus VV (lung only) before you interpret hypoxia.
- Chatter is often volume or a kink; emergency clamp is a trained-partner skill.
- Inverter, strapped console, helium, and a receiving team that already runs this device.
You inherit an intra-aortic balloon pump for an unpressurized climb. What is the correct altitude and timing plan?
An Impella patient's console alarms suction and the displayed flow collapses during loading. What is the best next interpretation?
Which ECMO and destination statement is consistent with flight principles?