A 70 kg, 55-year-old man undergoes a 4-hour major abdominal surgery. Postoperatively, he has received 4L of crystalloid intraoperatively. On Day 1 post-op, he is anuric (urine output 10 mL/hour), BP 100/65 mmHg, HR 98 bpm, JVP is normal, chest is clear, and serum lactate is 3.2 mmol/L. A fluid responsiveness test using passive leg raising (PLR) shows no change in stroke volume (SV). The most appropriate interpretation and management is:

• A Fluid-unresponsive — patient is fluid-overloaded or has cardiogenic/distributive shock; vasopressors (noradrenaline) and/or reassess the cause of oliguria ✓
• B Fluid-responsive — give 500 mL IV fluid bolus
• C PLR is unreliable post-surgery; give 1L fluid challenge regardless
• D Fluid-unresponsive — diuretics should be started for oliguria

Explanation

Passive leg raising tests fluid responsiveness by auto-transfusing ~300 mL blood from the lower limbs to the central circulation — an increase in cardiac output/SV ≥10% indicates preload-dependence (fluid responsiveness). A negative PLR test (no SV change) indicates the patient is on the flat part of the Frank-Starling curve; further fluid administration will cause fluid overload without hemodynamic benefit. In postoperative oliguria with normal JVP and negative PLR, the cause is likely functional (vasodilation, early distributive pattern) or poor cardiac output from a non-volume-dependent state — vasopressors (noradrenaline for hypotension/high SVR requirement) and further diagnostic assessment are indicated. Diuretics are contraindicated in this hemodynamically unstable patient.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.