B.7. Having made the diagnosis of cardiac tamponade, what additional investigations are required before surgery?
Answer:
This patient has cardiac tamponade likely arising from postcardiac surgery bleeding. Although her vital signs are adequate, she is at risk for decompensation and should undergo a focused, expedited workup so that surgical treatment is not delayed. Point-of-care blood tests such as arterial blood gas (ABG) analysis and rotational thromboelastometry (ROTEM) or thromboelastography (TEG) can provide rapid, relevant information to guide preoperative preparation. An ABG can reveal a low pH and/or elevated lactate from hypoperfusion, gas exchange abnormalities, electrolyte derangements, and anemia. ROTEM or TEG provides real-time information on coagulation factor activity and clotting kinetics. Formal laboratory investigations should include a complete blood count, coagulation profile, and blood type and cross-match. The presence of anemia, thrombocytopenia, or coagulation abnormalities guides the type and amount of blood products required, and should be immediately available in the operating room before surgery. A baseline ECG can provide additional information if the suspicion for ischemia is high and provide supportive information such as low-voltage QRS complexes, electrical alternans, and RV strain. Although radiographic findings were discussed earlier, a chest radiograph or computed tomography (CT) is unlikely to add diagnostic value in this patient and should not delay surgery unless there is a strong clinical indication.
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