Lung ultrasound-guided fluid management reduced postoperative lung water and hypoxaemia in percutaneous nephrolithotomy

Design

Randomised controlled trial, lung ultrasound-guided vs CVP-guided fluid management

Population

181 patients undergoing elective percutaneous nephrolithotomy

Primary outcome

Increase in extravascular lung water within 30 minutes after surgery, and postoperative hypoxaemia

Effect

Lower incidence and severity of lung water increase and less hypoxaemia with lung ultrasound (all P < 0.001); no effect sizes in abstract

During percutaneous nephrolithotomy (PCNL), irrigation fluid can be absorbed and raise extravascular lung water. This randomised trial in 181 patients having elective PCNL compared conventional fluid management guided by central venous pressure with a protocol guided by lung ultrasound and predefined thresholds for intervention, including furosemide.

The primary outcomes were the incidence and severity of increased extravascular lung water within 30 minutes after surgery, and postoperative hypoxaemia. The lung ultrasound group had a lower incidence and severity of the rise and less hypoxaemia (all P < 0.001). Lung ultrasound scores and central venous pressure were lower at the later time points, and extubation time and recovery-room stay were shorter (P < 0.05). The abstract gives no effect sizes or event counts.

The trial was in a single procedure and the abstract does not say whether anyone was blinded or whether longer-term outcomes differed. It is a perioperative study with relevance to nephrologists who care for patients with kidney stones and for those at risk of fluid overload.

• Consider lung ultrasound to detect fluid absorption during PCNL rather than relying on central venous pressure alone.
• The lung ultrasound protocol reduced postoperative hypoxaemia and shortened recovery-room stay.
• Event counts were not reported in the abstract, so read the full paper before changing a protocol.
• Be alert to fluid overload in patients with reduced kidney function who undergo irrigation-based procedures.

Why it matters

It suggests that bedside imaging catches fluid overload earlier than a pressure measurement.

Don't overread it

Event rates and effect sizes were not given in the abstract, and the trial studied a single procedure in one setting.

The statistics, in plain English

A P value below 0.001 shows the difference was unlikely to be chance, but it does not show how large the difference was. The abstract gives no numbers for event rates.

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