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Ventilatory and metabolic changes during high efficiency hemodialysis

1992; Elsevier BV; Volume: 41; Issue: 4 Linguagem: Inglês

10.1038/ki.1992.162

1523-1755

Tommy Symreng, Michael J. Flanigan, Victoria S. Lim,

Mechanical Circulatory Support Devices

Ventilatory and metabolic changes during high efficiency hemodialysis.Ventilatory and metabolic changes were measured in seven patients undergoing high efficiency hemodialysis using a cuprophane dialyzer and bicarbonate-containing dialysate, At an HCO3 concentration of 35 mEqfliter and a mean in vivo urea clearance of 3.6 mI/kg/mm, hypoxemia was not detected during dialysis (Pa02 was 14.00 and 13.60 kPa before and during dialysis).The new findings, related to high efficiency bicarbonate dialysis, include a sustained rise in minute ventilation (YE, 6.1 to 6.8 liter/mm, P < 0.01), an increase in CO excretion (VCO2, 194 to 214 mI/mm, P < 0.05), and 02 consumption (V02, 215 to 246 mI/mm, P < 0.05).The increment in VE and VCO, was attributed to the high flux rate of bicarbonate while the rise in V02 is likely the result of metabolic alkalosis.Arterial pH rose from 7.40 to 7.49 mm Hg and serum HCO3 increased from 23.8 to 29.2 mEq/liter, while pCO2 remained normal at 5.07 kPa throughout the study.The acid-base status of the blood changed from that of a metabolic acidosis to that of a respiratory acidosis across the dialyzer where the pH decreased from 7.47 to 7.41 and pCO2 rose from 5.31 to 7.72 kPa.These data indicate that a healthy ventilatory response is needed to excrete the excess CO2 generated during high efficiency bicarbonate hemodialysis.The significance and etiology of the elevated 02 consumption is undetermined.In the era of conventional hemodialysis, acetate was the buffer base in dialysate and hypoxemia the most prevalent respiratory change 11-SI.Such hypoxemia is primarily due to CO2 loss across the dialyzer [6] with a minor contribution from an increasing alveolar-arterial oxygen gradient due presumably to leukocyte/platelet aggregates [2].In this situation, hypoxemia is accompanied by reduced minute ventilation [7].With the introduction of high efficiency hemodialysis and the use of bicarbonate buffer, there is a rapid flux of bicarbonate from the dialysate to the patient.We hypothesized that this flux would generate excess CO2 and require an increase in ventilation to maintain acid-base balance.This report focuses on the ventilatory and metabolic changes of high efficiency hemodialysis. Methods Study subjects and dialysis treatmentSeven hemodialysis patients were recruited for this study, their demographic and clinical data are listed in Table 1.All participants were clinically stable and without intercurrent