Correlations between physiological parameters related with kidney function and minute-by-minute urine output

Area of Science:

• Physiology
• Nephrology
• Critical Care Medicine

Background:

• Minute-by-minute urine output (UOm) measurement devices are emerging.
• The correlation between UOm and physiological parameters in normal and diseased states, particularly those with vascular dysfunction, remains unclear.
• Understanding UOm's pathophysiological interpretation is crucial for assessing kidney perfusion.

Purpose of the Study:

• To analyze the correlations between UOm and physiological parameters related to kidney perfusion.
• To provide insights into the pathophysiological interpretation of UOm.
• To investigate the relationship between UOm and renal blood flow.

Main Methods:

• 14 male pigs were studied under anesthetized, tracheostomized, and mechanically ventilated conditions.
• Measurements included systemic and pulmonary artery blood pressure, carotid artery blood flow, and total, cortical, and medullary renal blood flows (Q_REN, Q_COR, Q_MED), along with renal resistive index (RRI).
• Animals were divided into nonseptic and septic groups, with septic groups receiving different resuscitation fluid rates, and monitored for 5 hours post-sepsis induction.

Main Results:

• In septic animals, UOm showed strong positive correlations with Q_REN and Q_MED, and a negative correlation with Q_COR.
• UOm was negatively correlated with mean pulmonary artery blood pressure (P_PA) and renal resistive index (RRI) in septic animals.
• Control animals exhibited weaker correlations between UOm and the measured physiological parameters.

Conclusions:

• Urine output (UOm) serves as a reliable physiological surrogate marker for total and regional renal blood flows.
• UOm is particularly valuable in assessing vascular resistance under septic conditions.
• The findings suggest that UOm may reflect glomerulo-tubular dysfunction during sepsis.