Intra-Aortic Balloon Pump (IABP) — Rapid Summary
Concept & Components
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Mechanism: Inflate in diastole → ↑diastolic & mean arterial pressure (MAP), ↑coronary/systemic perfusion; deflate at systolic onset → vacuum effect, ↓afterload.
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Hardware: Catheter with distal pressure lumen + helium inflation lumen (fast laminar flow) and a mobile console.
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Sizes (adult): 35 cc (<≈162 cm) and 40 cc (≈162–183 cm).
Triggers & “Auto”
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Triggers: ECG (default), Pressure (during CPR), Pacer V/AV or A, Internal (brief pauses in compressions/OR).
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Auto mode: Uses ECG + pressure algorithm; correct timing ~“most of the time.”
Indications (lecture framing)
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Cardiogenic shock refractory to ≥2 inotropes/pressors (evidence largely negative).
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Low CO post-CPB (weaning aid).
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Mechanical complications of AMI: Acute MR (papillary rupture) and post-MI VSD — strong benefit(afterload reduction → favors forward flow; ↓shunt).
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Intractable ischemia / left main pending CABG / adjunct to high-risk PCI: weak evidence.
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LV unloading on VA-ECMO.
Hemodynamic Effects & Bedside Assessment
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Effects: ↓SBP (~afterload drop), ↑DBP (augmentation), ↑MAP, ~20% CO rise (≈0.5–1.0 L/min), possible ↓HR.
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Augmented diastolic > native systolic (check at 1:1).
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Assisted aortic end-diastolic < native diastolic (set 1:2).
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Assisted systolic < native systolic (set 1:2).
Augmentation criteria (prove it works):
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Timing Errors (recognize & impact)
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Too early inflation / late deflation (long inflation time): harm—↑afterload, impedes ejection (“step on systole”).
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Late inflation / early deflation (short inflation time): loss of benefit—suboptimal augmentation/afterload reduction.
Contraindications
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Absolute: >mild aortic regurgitation; aortic dissection/major aneurysm.
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Relative: Uncontrolled sepsis/bleeding, severe PAD (access issues).
Insertion & Positioning
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Approaches: Femoral (common femoral); central (surgical, descending aorta); axillary (facilitates ambulation).
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Confirm: CXR tip ~2 cm above left main bronchus / distal to subclavian on TEE.
Complications
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Vascular: Limb/visceral ischemia, emboli, vascular injury, pseudoaneurysm, major bleed.
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Non-vascular: Sepsis, thrombocytopenia, stroke (rare, malposition/air).
Anticoagulation (context-dependent)
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No firm consensus; weigh thrombosis vs bleeding. Often avoided early post-cardiac surgery; commonly used in CCU AMI settings.
Weaning
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Preferred: Ratio wean (1:1 → 1:2 → 1:3), observe 4–6 h at each step.
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Alternative: Volume wean (reduce augmentation).
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Remove only when on minimal/off inotropes/pressors and hemodynamics/organ perfusion stable; keep 1:1 while awaiting removal, set standby during extraction.