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Gas Alarms/Balloon Pressure Waveform

During a cycle of inflation/deflation, helium is rapidly moved in and out of the balloon. The environment within the balloon and the surrounding forces that affect balloon behavior all contribute to a predictable pattern of gas flow and pressure. The Arrow International IABP consoles have in-line transducers that relay the pattern of gas pressure during the inflate/deflate cycle. The gas pressure characteristics are converted into a waveform that is reflective of the behavior of the gas. This transduced waveform can tell us much about the interaction of the balloon within the patient's aorta. Thorough understanding of the balloon pressure waveform is also important for efficient troubleshooting of the console as most of the alarms are based on this gas surveillance system.

1. Zero Baseline (on console)
2. Balloon Pressure Baseline
3. Rapid Inflation
4. Peak Inflation Artifact
5. Balloon Pressure Plateau (IAB fully inflated)
6. Rapid Deflation
7. Balloon Deflation Artifact
8. Return to Baseline (IAB fully deflated)
9. Duration of Balloon Cycle





BPW Height
Reflects the pressure in the aorta, therefore the plateau pressure on the BPW should be within +/-25mmHg of the Peak Diastolic Pressure.

BPW Width
Is approximately the duration in which the balloon is inflated.


 

Normal Variations

Tachycardia
Bradycardia


Hypertension
Hypotension


Abnormal Variations

Wide Inflation and/or Deflation Artifact

Note the wide inflation and deflation artifacts. This is generally indicative of something impeding the rapid inflation and deflation of the IAB, such as kinking of the gas lumen. This may result in poor augmentation and/or poor afterload reduction. It may also lead to helium/gas loss alarms in higher Heart Rates when in a 1:1 assist ratio. It may precede high pressure/kinked line alarms.

The goal is to eliminate the partial obstruction, if possible, to enable the IABP to assist the patient better by moving the helium more rapidly.


Helium Loss / Gas Loss / Gas Leakage Alarms

Note the BPW baseline is below 0. This indicates that a portion of the gas that went out to the balloon did not return to the pump.
  1. Observe for blood in this gas tubing. If even a slight amount were present, it would indicate a balloon rupture. Do not resume pumping. Notify physician immediately and prepare for IAB removal.
  2. Check connections where gas tubing connects to IAB and to pump. Secure if loose.
  3. Check for kinks, as they may trap gas in the IAB.
  4. If water is present in the gas tubing, remove the condensation. Pushing the helium through the water during inflation and deflation slows down gas transition. If gas transition is prolonged too much, it can create alarms.
  5. The alarm may occur during descent in air transport due to gas shrinkage during loss of altitude. Reset the alarm and restart pumping. The volume will be adjusted automatically for current barometric pressure.

High Pressure / Kinked Line Alarm

Note that the plateau pressure is still greater than 250mmHg when it is time to deflate. This indicates that not all of the gas could enter the balloon. It is generally due to a kink in the catheter, either internal to the patient or external.
  1. Reposition patient. Keep affected leg straight. Use rolled towel under hip to hyperextend hip.
  2. Apply slight traction to the catheter if suspect kinking at the insertion site or in the artery.
  3. The distal portion of the IAB may be in the sheath if a long introducer sheath was used. Pull sheath back until IAB bladder has exited the sheath.
  4. Introducer sheath may be kinked which in turn is kinking the balloon. Suspect this particularly if placement of the sheath was difficult. Pull sheath back or rotate sheath a partial turn.
  5. Check placement of the balloon; it may be too high or too low.
  6. IAB may be partially wrapped if alarm occurs shortly after insertion. Take steps to facilitate unwrapping (consult IAB manufacturer).
  7. The balloon may be too large for the patient. Reduce the helium volume the balloon is inflated with. It is recommended to not reduce the volume below 2/3 of maximum. For example, do not decrease volume in a 40cc IAB below 27cc.

High Baseline / Fill Pressure

Indicates too much gas in the system.
 
  1. Check for intermittent obstruction of gas lumen.
  2. Overfill of system.
  3. This condition may occur during ascent in air transport since gas expands as you go up in altitude. Reset the alarm and restart pumping. The volume will be adjusted automatically for current barometric pressure.
  4. In AutoCAT® or TransAct® the vent valve may be malfunctioning.
  5. In the AutoCAT, ensure that the tubing to the condensation bottle (located behind the helium tank) is not kinked.

Caution: U.S. Federal Law limits these devices to sale by or on order of a physician. Contents of unopened, undamaged package are sterile. Disposable. Refer to package insert for current warnings, indications, contraindications, precautions, and instructions for use.