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PCO 2 electrodes at the surface of the kidney detect ischaemia
Author(s) -
Tønnessen T. I.,
Kvarstein G.
Publication year - 1996
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1996.tb04481.x
Subject(s) - medicine , kidney , blood flow , cannula , artery , renal artery , ischemia , venous blood , vein , cardiology , anesthesia , surgery
Background: Under ischaemic (anaerobic) conditions there will be an accumulation of CO 2 in the tissue secondary to a build up of protons that is buffered by HCO 3 ‐ . We reasoned that CO 2 could be measured at the surface of the kidney by PCO 2 electrodes to detect ischaemic conditions. Methods: Anaesthetized, mechanically ventilated pigs (25–30 kg) were investigated. Two acute porcine models, one of haemorrhagic shock and one of renal artery stenosis were used. Renal blood flow was gradually decreased, either by successive episodes of bleeding through the arterial cannula or by successive snaring of the renal artery. Results: In both models we found that with decreased blood flow but maintained aerobic metabolism (supply independence) PCO 2 both at the surface of the kidney and in the renal vein increased by 2–3 kPa. Thus, the tissue‐venous PCO 2 difference did not change much. At DO 2crit , i.e., at the transition to supply‐dependent O 2 consumption, the tissue PCO 2 started to increase rapidly, as did the tissue‐venous PCO 2 difference. This is compatible with the notion that a hallmark of ischaemia is decreased ability of the blood to transport away waste products because the contact between large parts of tissue and blood is virtually non‐existent. In the renal artery stenosis model kidney surface PCO 2 values rose from a baseline of 6.6±0.6 kPa (mean±SEM) to a value near DO 2crit of 10.6±0.8 kPa, reaching a final value of 29.9±3.5 kPa at no flow. PCO 2 in the renal vein, however, reached a maximum of only 8.2±0.6 kPa. Numbers very similar to these were also found in the haemorrhagic model. The urine production decreased before the onset of ischaemia. When surface PCO 2 values increased sharply indicating ischaemia, the urine production was zero. Lactate production by the kidney correlated very well with increasing tissue PCO 2 values further corroborating that anaerobic metabolism was detected with the electrodes. Conclusion: We conclude that PCO 2 electrodes placed at the surface of the kidney detect renal cortical ischaemia.