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S H Nolte

Publications and source records attributed to S H Nolte.

4 recordsLinked to original sources
PubMed1991

Extracorporeal CO2 removal with hemodialysis (ECBicCO2R): how to make up for the bicarbonate loss?

Hemodialysis is a powerful tool for extracorporeal CO2 removal, because CO2 can be eliminated both as gas and as bicarbonate with blood flow rates as low as 10-15 ml/kg/min. An unsolved problem remains, however: how to make up for the bicarbonate loss. In an animal model we investigated three methods of realkalinisation: a) indirect alkalinisation with salts of organic anions (acetate, lactate, citrate, pyruvate, fumarate, succinate, malate) b) direct realkalinisation with hydroxyl ions (NaOH) c) direct alkalinisation with TRIS as "CO2-buffer". a) The decrease of pulmonary CO2 elimination depended on metabolism: acetate and lactate were metabolized at a rate of 1.8-3.5 mmol/min, thus allowing a steady-state elimination of 40-75 mmol CO2/min (25-40% of CO2 production). The other organic acids were not metabolized sufficiently to achieve a measurable reduction of pulmonary CO2 elimination. CO2 removal was quantitatively the same as during routine acetate hemodialysis and could not be increased using other organic acids. b) NaOH alone, through theoretically the best substitute for NaHCO3, had serious side effects and led to an increase in pulmonary artery pressure. c) with TRIS at a rate of 5 mmol/min, all metabolic CO2 could be removed for up to seven hours without clinical side effects, but not for longer periods. We conclude that a combination treatment for realkalinisation has to be worked out to compensate for the bicarbonate loss.

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PubMedDate not supplied

Hemodialysis for extracorporeal bicarbonate/CO2 removal (ECBicCO2R) and apneic oxygenation for respiratory failure in the newborn. Theory and preliminary results in animal experiments.

Extracorporeal techniques for respiratory support in the newborn are feasible, as the growth of neonatal extracorporeal membrane oxygenation (ECMO) has demonstrated. It has been shown, however, that even in severely damaged lungs, sufficient oxygenation and gas exchange can be maintained only by removing CO2 in an extracorporeal circuit, i.e., extracorporeal CO2 removal (ECCO2R). To demonstrate the effectiveness of CO2 removal in a bicarbonate-free hemodialysis procedure, CO2 removal was measured during routine acetate hemodialysis in 22 patients on renal replacement therapy for end-stage renal disease. By comparison of predialyzer and postdialyzer total CO2, an overall CO2 removal of 79.1 +/- 15.1 ml/min was measured in the blood and 77.0 +/- 19.5 ml/min in the dialysate; this was approximately one third of the entire metabolic CO2 production and probably accounted for the secondary hypoxia during acetate hemodialysis. To use bicarbonate-free hemodialysis for total metabolic CO2 removal, acetate dialysate was modified with lactate, phosphate buffer, and sodium hydroxide to compensate for the bicarbonate loss. In sheep, apneic oxygenation could be achieved with blood flow rates as low as 10-15 ml/kg/min for 4-6 hours. These preliminary data suggest that a hemodialysis procedure for bicarbonate and CO2 elimination (ECBicCO2R) could be an efficient method for CO2 removal requiring much lower blood flow rates than techniques presently in use.

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