A client receiving total parenteral nutrition (TPN) develops sudden onset of shortness of breath, chest pain, and a decrease in SpO2. The central line was just changed. What complication should the nurse suspect and what is the priority action?

AIR EMBOLISM: CAUSE: Air enters the central venous system through the central line during tubing changes, disconnections, or catheter removal; SIGNS: Sudden onset dyspnoea, chest pain, decreased SpO2, tachycardia, 'millwheel' murmur (churning sound from air in heart); EMERGENCY RESPONSE: CLAMP the line immediately to stop further air entry; LEFT LATERAL TRENDELENBURG (Durant's manoeuvre): Positions the right atrium above the right ventricular outflow tract — traps air in the right atrium rather than allowing it to obstruct the pulmonary outflow; OXYGEN: High-flow 100% O2 (increases nitrogen washout — air is primarily nitrogen); CALL FOR HELP: This is a life-threatening emergency; PREVENTION: Keep all central line connections Luer-locked; use air-elimination filters; have patient hold breath during tubing changes (Valsalva manoeuvre); use chlorhexidine prep and technique to minimise opening time; COMPARISON: Pneumothorax (from central line insertion) presents differently — unilateral breath sounds, tracheal deviation, diagnosed by CXR.