Goal-directed fluid therapy (GDFT) during major abdominal surgery uses which parameter MOST reliably to predict fluid responsiveness in mechanically ventilated patients?
- A Central venous pressure (CVP) <8 mmHg
- B Urine output <0.5 mL/kg/hr for 1 hour
- C Pulse pressure variation (PPV) >13% ✓
- D Pulmonary artery wedge pressure <12 mmHg
Correct answer: C. Pulse pressure variation (PPV) >13%
Explanation
Pulse pressure variation (PPV) is a dynamic functional haemodynamic parameter that exploits the heart-lung interaction during positive-pressure ventilation. A PPV >13% reliably predicts fluid responsiveness (i.e., cardiac output will increase with a fluid challenge) because it reflects cyclical changes in LV preload from intrathoracic pressure swings. Static parameters like CVP and PAWP poorly predict fluid responsiveness due to individual variation in ventricular compliance. Urine output is a late indicator and affected by non-volume factors (ADH, renal function).
Reference: Morgan & Mikhail's Clinical Anesthesiology, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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