Continuous tissue pH monitoring in critically ill neonates

Continuous tissue pH was measured using a minaturized glass electrode in 21 sick term and preterm infants. Tissue pH correlated well with arterial (r = 0.87) and capillary pH (r = 0.90) during the steady state. However, tpH was lower than arterial pH during hypoperfusion and state of shock. Improvement in tissue perfusion resulted in improvement in tpH and good correlation with arterial pH. The electrode was also sensitive to changes in carbon dioxide tension and adminitration of buffer. The good correlation with arterial pH and the feasibility of continuous recording of tissue pH makes it a useful instrument for monitoring the acid-base status of critically ill neonates.