Pulmonary artery catheter (PAC) thermodilution measures cardiac output. A sudden decrease in ETCO2 from 38 to 15 mmHg during a total hip replacement procedure should prompt immediate consideration of which catastrophic complication?
- A Bronchospasm
- B Malignant hyperthermia
- C Venous air embolism (VAE) ✓
- D Oesophageal intubation
Explanation
A sudden decrease in end-tidal CO2 during orthopaedic surgery (particularly hip/knee arthroplasty during cementing or femoral reaming) signals venous air embolism. Air enters the venous system, creating an air lock in the right heart and pulmonary vasculature, causing increased dead space, reduced pulmonary perfusion, and decreased ETCO2. Simultaneously, transpulmonary pressure increases and cardiac output falls. Management includes informing the surgeon to flood the wound and stop air entry, positioning left lateral head-down (Durant manoeuvre), aspiration via central venous catheter if placed (right atrium), 100% oxygen, and haemodynamic support. ETCO2 is the earliest monitoring indicator of VAE.
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.