Pulmonary ventilation during hemodialysis.

During hemodialysis a decrease in pulmonary ventilation has been reported. The elimination of CO2 across the dialyzer has been suggested as the cause of the pulmonary hypoventilation. Our purpose was to analyze the factors that could have influenced the pulmonary ventilation of 7 patients with chronic renal failure during hemodialysis, performed against an acetate dialysate with constant addition of CO2, bubbling into the dialysis bath. In spite of the large volume of CO2 mainly as bicarbonate, eliminated across the dialyzer there was no significant decrease of ventilation. The values of pH in the venous line were extremely low and the values of PvCO2 were artificially maintained around 35.0 mm Hg. Thus, the total CO2 delivered to the lungs, but mainly the levels of pH and PCO2 in the venous line play an important role in the control of pulmonary ventilation of these patients.