Question 11

College Answer

Potential causes of this scenario include:

-     pericardial tamponade

-     graft occlusion by clot/spasm/kinking/stitch

-     complete heart block

-     non-specific events: eg disconnection leading to severe hypoxia/bradycardia and myocardial ischaemia, pulmonary embolus

The most appropriate course of action is:

-     bag the patient with 100%

-     administer immediately available inotrope (aramine or adrenaline)

-     commence ECM if pulseless

-     obtain and use chest opening pack

-     internal cardiac massage

-     if the problem is not immediately amenable to therapy eg relief of tamponade,   organise cardiopulmonary bypass to rest the heart and allow exploration of the grafts.

Discussion

There is little to add to the college answer.

One would begin to manage such a patient in a similar algorithmic manner which is associated with any arrest situation. The major differences lie in the potential for open cardiac massage and return to cardiopulmonary bypass.

A systematic approach would resemble this:

• A - ensure ETT is patent and in position
• B - bag the patient with 100% FiO2
• C - commence infusion of inotropes; given that the patient is bradycardic I marvel at the college's choice of metaraminol as a potential rescue agent. Adrenaline lives in the same trolley, people. Commence CPR if there is no response to this. 
  • As the drugs are being prepared for infusion, one should strongly consider pacing the patient through the epicardial leads if these are available. It is again bizarre that the college do not mention this in their model answer. A sensible rate would be about 80-100.
• D - paralyse the patient to simplify resuscitation and decrease chest wall resistance to ventilation;
• E - ensure the patient is not profoundly hypothermic (that could explain the bradycardia and hypotension
• Think about the 4 Hs and 4 Ts:
  • Hypoxia could have caused the bradycardia; ensure the patient is well oxygenated by manual bag-mask ventilation
  • Electrolyte derangement can be easily excluded with ABG, and managed as apropriate (depending on the disturbance)
  • Hypothermia can be addressed by use of external warming devices, warmed fluids, or a warmed dialysis/ECMO circuit
  • Hypovolemia can be addessed with vigorous fluid resuscitation
  • Myocardial infarction due to graft failure needs to be excluded, and an ECG needs to be performed as soon as is practical
  • Tension pneumothorax needs to be excluded by careful physical examination and inspection of the chest drains
  • Cardiac tamponade may be the cause, and can be excluded rapidly with bedside TTE
  • Check whether any antiarrhytmics were accidentally given (eg. amiodarone given too fast)
• If no immediately reversible cause is found and the patient is not responding to an infusion of adrenaline, surgeons should be contacted and a return to theatre should be organised. While waiting for this, cardiopulmonary bypass should recommence.

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