@variablepulserate Low fluid intake over preceding two days & low blood pressure combined with the pneumonia just threw the whole system out. The issue with the potential loss of kidney function was whether urine production would resume if the blood pressure was able to be brought up to normal levels in a reasonable timeframe.
So they fitted a visual gauge to observe kidney function: a catheter.
Fortunately I responded quickly to the infusion of three litres of saline over 15 hours plus whatever fluid was used as the carrier for the IV antibiotics.