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Adrenal insufficiency (Was the patient steroid dependent pre-operatively?)

A “typical” presentation would be a patient who had a normal ejection fraction pre-operatively, underwent uncomplicated ACBG, initially had excellent hemodynamic parameters, bled from the mediastinal sumps moderately, then the bleeding “stopped” or blood ceased to drain from the sumps. (Always check to make sure the sumps are not obstructed). This is followed by hemodynamic deterioration with tachycardia, declining cardiac output and stroke volume, and decreasing mixed venous oxygen. The urine output typically decreases and other signs of end-organ hypoperfusion develop including CNS changes and acidosis.

  1. Search for alternate explanations for the low cardiac output (i.e., hypovolemia, myocardial ischemia, etc.).
  2. Assure patency of the sumps.
  3. Look for “equalization” of central pressures. In “classic” cardiac tamponade, the pericardium is intact and the raised pericardial pressures are transmitted equally to all four cardiac chambers. This results in an elevation and equalization of the CVP, PCWP, and PAD associated with low CO. (CVP=PCWP=PAD). In the post-op cardiac surgery patient, it is possible to have a small, well-localized clot that impedes filling to only one chamber and thus cause unequal pressure changes.. For example, a right sided clot may raise only the CVP and impair filling to only the right atrium or ventricle.
  4. Look for a “loss of the y-descent” on the CVP or PCWP tracing. Remember that the “y-descent” occurs at the beginning of diastole when the AV valves open. In the usual situation, there is a pressure gradient between the atrium and the ventricle because the ventricle has just emptied and the atrium has filled while the AV valve was closed during systole. Thus, there is a rapid transfer of blood from atrium to ventricle and the pressure drops significantly in the atrium – the “y-descent”. In tamponade, the external pressure on the ventricle decreases the pressure gradient between the atrium and the ventricle. The atrium does not empty into the ventricle rapidly because ventricular filling is impeded. Thus the “y-descent” is minimal or absent.
  5. Low voltages on the ECG or an increase in the width of the superior mediastinum on serial chest X-rays are generally poorly sensitive or specific. They are rarely helpful.
  6. Echocardiogram. This is the best test to assess for tamponade. Often a trans-esophageal Echo (TEE) will be required because of poor “windows” common in the post-operative state with Trans-thoracic echo (TTE). The Echocardiographer on call should be paged after discussion with the ICU Fellow or Attending.
  7. The only treatment for cardiac tamponade is return to the OR, re-sternotomy, and evacuation of the clot with hemostasis of any ongoing bleeding. The cardiac surgery fellow should be notified early if potential tamponade is suspected. Volume resuscitation, inotropes, and vasopressors are temporizing measures only in this situation.
  8. If a patient with suspected tamponade suddenly deteriorates and develops PEA (pulseless electrical activity) an urgent sternotomy should be done in the ICU. This should only be done by the Cardiac Surgeon or Cardiac Surgery Fellow. Page them STAT and move the thoracotomy tray to the bedside while following standard ACLS algorithms.