identifying correct position of IABP on xray

[Srishti Jain]

- To avoid occlusion of the left subclavian artery and visceral and renal arteries, its tip should be slightly cephalad to the adjacent carina (2 ^nd -3 ^rd intercostal space). The balloon should not occlude more than 85-90% of the aortic diameter. Balloon rupture with air embolization and septicemia are rare potential complications.
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Case: After uneventful insertion of IABP (intra-aortic balloon pump) - you have been informed that, it will take a while before CXR can confirm proper location of tip of IABP. What is one easy method to determine that you have not 'over-shooted' the tip of IABP?


Answer: Check the left radial pulse

Ideally, the tip of the balloon should be positioned 2–3 cm distal to the origin of the left subclavian artery (LSCA). This position results in maximum augmentation of coronary artery flow although minimizing the risk of embolization to the cerebral vessels and occlusion of the LSCA. If you have good left radial artery pulsation, probably your tip of IABP is distal to LSCA.



Carina as a Radiographic Landmark for Positioning the IABP

There are reports in literature that targeting tip of Intraaortic Balloon Pump (IABP) just below the aortic knob on CXR radiologically may still cause occlusion of left subclavian artery (upto 7 - 16%). 1,2.

See this interesting another approach to target carina as a Useful Radiographic Landmark for Positioning the Intraaortic Balloon Pump.

METHODS: The distance from the top of the distal aortic arch (aortic knob) to the left subclavian artery (LSCA) on three-dimensional computed tomography angiography in 100 patients, was measured. The distance from the level of the LSCA origin to the level of the carina was also measured using three-dimensional computed tomography in 150 additional patients.

RESULTS: In 16% of the aortic knob study population, the LSCA to aortic knob distance was <0 cm or 0 cm. The median distance from the LSCA to the carina was 42 mm (range: 30–63 mm). In the carina study population, the origin of the LSCA was 35–55 mm above the carina in 95.3% of patients.


CONCLUSION:

In 16% of patients, the IABP was too close to the LSCA origin when it was placed at the aortic knob, whereas Positioning the IABP at 2 cm above the carina provided an adequate position for the IABP tip (1.5–3.5 cm distal to the origin of the LSCA) in 95.3% of patients.

The carina may be a more reliable landmark for positioning the IABP than the aortic knob.

Dr. Srishti Jain

M.B.B.S -GSMC, KEMH, Mumbai

M.D ,D.N.B Pulmonary Medicine 

Gold Medalist 

Fellow (F.N.B Critical Care) 

Prince Aly Khan Hospital ,Mumbai

Cell No.9702022320