Weaning From Iabp

Weaning From IABP  Ri

王昭閎

IntraAortic Balloon Pump

Settings: catheter-mounted, balloon volume 30-50 ml, central lumen, helium, synchronization. Net effect: myocardial oxygen supply/demand ratio with a small increase in systemic perfusion (≦0.5L/min) Timing: Pre-,Peri-,Post-op

IABP Waveforms

IABP

Early Inflation

Waveforms

Late Inflation

IABP

Early Deflation

Waveforms

Late Deflation

Indications       

Cardiogenic shock Mechanical complication of AMI In association with CABG In association with nonsurgical revascularization Stabilization of cardiac transplant recipient before insertion of ventricular assist device Postinfarction angina Ventricular arrhythmias related to ischemia

Contraindications  Absolute Contraindications 

Aortic valve insufficiency; Aortic dissection

 Relative Contraindications 



Femoral arterial insertion: Abdominal aortic aneurysm; Severe calcific aortoiliac or femoral arterial disease Percutaneous insertion: Recent ipsilateral groin incision; Morbid obesity

Complications  Complication rate: 5-47%  Limb ischemia; aortic dissection; aortoiliac

laceration; perforation; deep wound infection  Bleeding at insertion site; superficial wound infections; asymptomatic loss of peripheral pulse; lymphocele

Weaning from IABP   

Continued satisfactory LV performance Augmentation curve remains < SBP No further increase in CO at 1:1 assist rate in comparinson with 1:2

Weaning from IABP  No experimental or clinical studies have

been done to evaluate the most effective weaning  Traditional method: reduce the assist rate from 1:1 to 1:2, etc, because all consoles are equipped with it.  The method of weaning is, at best, selected arbitrarily.

Weaning from IABP     

Traditional method:↓Assist rate while maintaining augmentation. New method: ↓Augmentation while rate at 1:1 Goal: assure satisfactory cardiac performance independent of balloon pump assist. Weaning is done in a gradual fashion over a preset time interval (in two phases) Criteria for initiation of IABP weaning: a patient must be in hemodynamic class I (Shock box)

Weaning from IABP

Shock Box       

Left Ventricular Stroke Work Index LVSWI = (SV/BSA)*(MAPPCWP)*(0.0136) Normal = 45-75 Class I: Minimal failure group Class II: Hypovolemic group Class III: HypervolemicHyperdynamic group Class IV: Classic cardiogenic shock (HypervolemicHypodynamic group)

Protocols        

Initial set of hemodynamic data Phase I: 1:2 + 100% V.S. 75% + 1:1 Appropriate therapeutic measure Parameters:↓LVSWI or↑PWP > 20% If not class I, 1:1 + 100% for more 12-24 hr Phase II: 1:3 + 100% V.S. 50% + 1:1 Flutter mode (<25%) for 10-15 min; Prevent clot Augmentation(%) adjustment by pressure; variable balloon volume changes

Results

75% + 1:1 similar to 1:2 + 100%  Class I p’t in Phase II: min. change between phases 



Phase II as balloon “off” or “flutter”

Combined methods is safe and reliable  IABP < 3-4 hrs, weaning may be shortened to 1-2 hrs  Average time from class IV to I: 48 hrs 

One Patient’s Data

Criteria for Variant Condition

 

Preoperatively or acute ventricular dysfunction ~1 hr devided into two 30-minute phases

Criteria for Variant Condition

  

Emergency basis (at the completion of a cardiac operation), IABP should not be DC early after satisfactory response Maybe 12-18 hours later in ICU

Criteria for Variant Condition

Weaning in Special Situations  Prolonged Respiratory Support    

Never weaning simultaneously DC respiratory support first, if possible 12-24 hr later, weaning may be attempted COPD or ARDS, IABP may be weaned first

 Pressor Therapy      

Vasopressor to the lowest level before weaning Exception: Leg ischemia. Early removal or change site Change all the pressor drugs to dopamine or dobutamine Decrease to <5mcg/kg/min, then weaning Within 12-24 hr after DC IABP, decrease in conc. and DC DC pressor but keep IABP as bridge to trans.

Thanks for Your Attention

References 

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Clinical Application of Intra-Aortic Balloon Pump, Third Edition. Hooshang Bolooki. Counterpulsation: historical background, technical improvements, hemodynamic and metabolic effects," which appears in Volume 84 (1994) of the journal Cardiology (pp. 156-167). Braunwald: Heart Disease: A Textbook of Cardiovascular Medicine, 6th ed.