Reference Guide
CVICU Devices & Troubleshooting
IABP, Impella, ECMO, pacemakers, and chest tubes
Mechanism & Timing
- Helium balloon (30–50 mL) in descending aorta
- Inflation in diastole → augments coronary/cerebral perfusion
- Deflation in early systole → reduces LV afterload
- Triggered by ECG R-wave (preferred) or arterial pressure
- Augmentation ratio: 1:1 (full), 1:2, 1:3 (weaning)
- Effects: ↑ diastolic BP, ↓ LVEDP/PCWP, modest ↑ CO (~0.5 L/min)
Timing Errors
| Error | Waveform Finding | Consequence |
|---|---|---|
| Early Inflation | Augmentation before dicrotic notch | ↑ LV afterload, premature aortic valve closure |
| Late Inflation | Augmentation after dicrotic notch | Suboptimal coronary perfusion |
| Early Deflation | Sharp drop before next systole | ↑ myocardial O₂ demand |
| Late Deflation | Augmented end-diastolic pressure ≥ unassisted | ↑ LV afterload, ↑ work |
Troubleshooting & Safety
- Poor augmentation: Check helium level, balloon position (tip 1–2 cm distal to L subclavian on CXR), timing/trigger, kinking
- Balloon rupture: Blood in helium line → emergent removal
- Limb ischemia: Check pulses hourly
- Contraindications: Severe aortic insufficiency, aortic dissection, severe PVD
Device Types & Position
- Impella 2.5: ~2.5 L/min flow
- Impella CP: ~3.5–4.0 L/min flow
- Impella 5.0/5.5: ~5.0–5.5 L/min (surgical cutdown)
- Impella RP: Right-sided, ~4 L/min
- Position (LV devices): Inlet 3–4 cm below aortic valve in LV; outlet in ascending aorta
- Display values: Performance level (P-level), motor current, placement signal
Common Alarms & Troubleshooting
- Suction alarm: Inlet against LV wall, hypovolemia, RV failure, tamponade → reduce P-level, give volume, check position with echo
- Position wrong: Device too far into aorta → advance into LV
- Low purge pressure: Check purge cassette, dextrose concentration
- Hemolysis: Monitor plasma free Hgb, LDH, urine color; consider repositioning or lowering P-level
- Anticoagulation: Heparin titrated to aPTT 50–70 (institutional protocol)
- Contraindications: Severe AI, mechanical aortic valve, LV thrombus, severe PVD
Configurations
| Mode | Configuration | Supports |
|---|---|---|
| VV-ECMO | Femoral vein → membrane → IJ or contralateral femoral vein | Lung only (oxygenation/ventilation) |
| VA-ECMO | Femoral/central vein → membrane → femoral or central artery | Heart + lung |
Targets & Management
- Flow: 50–80 mL/kg/min (4–6 L/min in adult)
- Sweep gas titrated to PaCO₂; FiO₂ on oxygenator titrated to post-membrane PaO₂
- MAP target: 65–75 mmHg
- Anticoagulation: UFH aPTT 50–80 or anti-Xa 0.3–0.7; bivalirudin for HIT
VA-ECMO Specific Issues
- North-South (Harlequin) Syndrome: Native cardiac output ejects deoxygenated blood to upper body. Monitor right radial ABG/SpO₂
- LV Distension: Increased afterload → pulmonary edema. Mitigate with inotropes, IABP, or Impella (ECPELLA)
- Limb Ischemia: Distal perfusion catheter; check NIRS, pulses
Troubleshooting
- Chugging/chattering: Hypovolemia, malposition, tamponade, pneumothorax → reduce flow, give volume, echo/CXR
- Rising transmembrane gradient (Δp >50 mmHg): Oxygenator clotting → plan exchange
- Hypoxemia on VV despite full settings: Recirculation (check pre-oxygenator SvO₂), inadequate flow, oxygenator failure
Modes & Initial Settings
- Modes (NBG code): AOO/VOO (asynchronous), AAI/VVI (demand), DDD (dual-chamber tracking), DDI (no atrial tracking)
- Rate: 80–90/min
- Output: 2× capture threshold (typically 5–10 mA)
- Sensitivity: 0.5–2 mV (atrial), 2–5 mV (ventricular)
- AV Delay: 150–200 ms
- Atrial or AV-sequential pacing preferred to preserve atrial kick (~20% of CO)
Troubleshooting
| Problem | Cause | Action |
|---|---|---|
| Failure to Capture | Threshold rise (fibrosis, displacement, metabolic), output too low | ↑ output to 2× threshold; check leads, K⁺, Mg²⁺, acid-base |
| Undersensing | Sensitivity number too high (less sensitive) | ↓ sensitivity number (more sensitive) |
| Oversensing | Sensitivity too low; EMI; T-wave/myopotentials | ↑ sensitivity number; check connections |
| Crosstalk (DDD) | V-channel senses A pace | Adjust blanking period or PVARP |
| Pacemaker-Mediated Tachycardia | DDD with retrograde conduction | Magnet/asynchronous, ↑ PVARP |
Routine Post-Op Management
- Mediastinal and pleural tubes to −20 cmH₂O suction
- Normal: First hour <200 mL; serosanguineous, decreasing over 24 h
- Tidaling (fluctuation with respiration) is expected; absence suggests obstruction or re-expansion
When to Call the Surgeon
- >200 mL/h for 2–4 hours
- >1500 mL/24 h
- Sudden increase in drainage
- Hemodynamic instability with equalization of CVP and PCWP (tamponade)
- Widening mediastinum on CXR
- Sudden cessation of drainage in a bleeding patient → suspect clot/tamponade → prepare for re-exploration
S.K.
The World-Class Cardiac Intensivist
This content is for educational reference only. Always follow institutional protocols and exercise clinical judgment.