Goal-directed fluid therapy (GDT) in major abdominal surgery uses dynamic parameters to guide fluid administration. Which parameter is MOST reliable in a mechanically ventilated patient with regular sinus rhythm?
- A Central venous pressure (CVP)
- B Pulmonary capillary wedge pressure (PCWP)
- C Pulse pressure variation (PPV) ✓
- D Urine output over 30 minutes
Correct answer: C. Pulse pressure variation (PPV)
Explanation
Pulse pressure variation (PPV) is a validated dynamic preload indicator based on cyclic changes in arterial pulse pressure during mechanical ventilation. PPV >13% predicts fluid responsiveness with high sensitivity and specificity in patients receiving controlled mechanical ventilation with tidal volumes ≥8 mL/kg and regular sinus rhythm. CVP and PCWP are static measures with poor predictive value for fluid responsiveness. Urine output is delayed and affected by many non-volume factors.
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
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