Post-extubation polyuria: characterization of an underrecognized phenomenon in a proof-of-concept study

Area of Science:

• Critical Care Medicine
• Respiratory Physiology
• Nephrology

Background:

• Mechanical ventilation (MV) discontinuation in intensive care units (ICUs) triggers significant physiological shifts.
• Extubation impacts respiratory function, hemodynamics, and fluid balance.
• The effect of extubation on urine output requires further investigation.

Purpose of the Study:

• To assess changes in urine output following the discontinuation of invasive mechanical ventilation (MV).

Main Methods:

• A prospective study involving 60 adult patients in an ICU who required MV for 1-15 days.
• Urine output was measured for 48 hours before and after extubation.
• Patients were placed on conventional oxygen therapy post-extubation.

Main Results:

• Urine output significantly increased post-extubation, from 2.1 L/day to 3.2 L/day (P < 0.001).
• The incidence of polyuria (urine output >3 L/day) rose from 27% to 57% (P < 0.001).
• Increased diuresis correlated with positive end-expiratory pressure (PEEP) levels during MV and was not linked to hemodynamic or renal impairment.

Conclusions:

• Discontinuation of MV is associated with a significant increase in urine output.
• Post-extubation polyuria may result from physiological responses to altered intrathoracic pressure and fluid redistribution.
• Further research is needed to elucidate the mechanisms underlying post-extubation polyuria.