Time: 0 second

OSCE 074: Intra-Arterial Balloon Pump

Introduction

You are working in the cardiothoracic ICU. A 74-year-old man has just been admitted from theatre following a 3-vessel CABG. He was difficult to wean from bypass and an intra-aortic balloon pump was inserted to aid his haemodynamics.

Related Pages:

Question No. 2

Q: What are the beneficial physiological effects of a balloon pump? (4 marks)

Answer No. 2

Effect of Inflation
  • Volume displacement results in increased diastolic pressure (30%):
    • Increases coronary perfusion pressure and flow 1
    • Increases myocardial oxygen delivery 1
  • Higher mean pressure increases renal and systemic perfusion 1
Effects of Deflation
  • Decreased afterload, and thus systolic pressure (10%), immediately following deflation:
    • Vacuum like effect promotes forward flow and increases stroke volume 1
    • Decreases end diastolic volume and ventricular wall stress
    • Reduces myocardial oxygen demand 1
Overall Effects
  • Improved ratio of myocardial oxygen supply to myocardial oxygen demand
  • Improved myocardial performance and increased cardiac output (up to 20%) 1

4

Question No. 3

Q: What can be used to trigger balloon inflation and deflation? (2 marks)

Answer No. 3

Trigger
Timings
Use & Limitations
ECG 1
Inflation: Middle of the T wave
Deflation: Peak of the R wave
Requires good ECG trace. May not be suitable if arrythmia present
Arterial Pressure Waveform 1
Inflation: At the dicrotic notch
Deflation: Just before the systolic upstroke
Requires the balloon pump to accurately sense ventricular systole and diastole
Asynchronous / Internal 1
Timings based upon pacing spikes depending upon mode
Requires patient to be 100% paced. Should not be used for on demand pacing
Pacing Device 1
Asynchronous augmentation based on a set rate (40-120/min)
Rarely used except in cases of cardiac arrest

2

Question No. 4

Q: What do the different pressures labelled on the waveform represent? (5 marks)

Answer No. 4

Normal IABP pressure waveform

5

Question No. 5

Q: What are the complications associated with the use of intra-aortic balloon pumps? (5 marks)

Answer No. 5

Vascular
  • False aneurysm 1
  • Aortic dissection 1
  • Haematoma formation 1
  • Vascular injury at time of insertion 1
  • Peripheral thrombotic embolization 1
  • Limb ischaemia & compartment syndrome1
  • Tamponade 1
Position Related
  • Upper limb ischemia (too proximal)
  • Spinal cord, renal and visceral ischaemia (too distal) 1
  • Cerebral ischaemia 1
Balloon Related
  • Balloon rupture and helium embolus 1
  • Immobility - balloon becomes lodged 1
  • Thrombocytopenia and haemolytic anaemia 1
Other
  • Infection (Insertion site or disseminated) 1

5

Case Information

The nurse calls you an hour later and reports that the cardiac output has dropped. He is concerned about the timing of the balloon pump and asks you to review the pressure waveform.

Related Pages:

Question No. 7

Q: What issue would this waveform suggest? (1 marks)

Answer No. 7

Timing
Physiological Effect
Waveform Features
Waveform
Late Inflation 1
  • Inflation of the IAB markedly after closure of the aortic valve
  • Reduction in duration of diastolic augmentation Suboptimal coronary artery perfusion
  • Balloon inflates after the dicrotic notch
  • Absence of sharp ‘V’ in the trace with reduced height of the diastolic augmentation peak

1

Question No. 8

Q: What issue would this waveform suggest? (1 marks)

Answer No. 8

Timing
Physiological Effect
Waveform Features
Waveform
Early Deflation 1
  • Reduction in duration of diastolic augmentation
  • Suboptimal coronary perfusion and potential for retrograde flow
  • Suboptimal afterload reduction
  • Increased myocardial oxygen consumption
  • Sharp decrease after diastolic augmentation

1

Question No. 9

Q: What issue would this waveform suggest? (1 marks)

Answer No. 9

Timing
Physiological Effect
Waveform Features
Waveform
Early Inflation 1
  • Potential premature closure of aortic valve
  • Reduction in cardiac output
  • Increased LVEDV and LVEDP
  • Increased myocardial oxygen consumption.
  • Balloon inflates before dicrotic notch
  • Diastolic augmentation encroaches onto systole
  • May be difficult to distinguish between two peaks

1

Question No. 10

Q: What issue would this waveform suggest? (1 marks)

Answer No. 10

Timing
Physiological Effect
Waveform Features
Waveform
Late Deflation 1
  • Deflation of the IAB after the onset of systole
  • Increased myocardial oxygen consumption
  • Prolonged isovolumetric contraction phase
  • Increased afterload
  • Reduction in cardiac output
  • Diastolic augmentation may appear widened
  • Assisted aortic end-diastolic pressure increased and may equal unassisted pressure
  • Rate of systolic pressure rise is prolonged

1

Review:

Total Score: /13

Total Time:

Return to home More questions Close Window

Related Pages: