OXYGEN, ARTERIAL BLOOD-GASES AND VENTILATION ARE UNCHANGED DURING DIALYSIS IN PATIENTS RECEIVING PRESSURE SUPPORT VENTILATION

This study was undertaken to observe whether dialysis-induced alveolar hypoventilation and arterial hypoxaemia occur during bicarbonate haem odialysis in patients receiving partial mechanical support with pressu re support ventilation. Nineteen patients admitted to the medical inte nsive care unit requiring mechanical ventilation and haemodialysis wer e enrolled. Arterial blood gas, white blood cell (WBC) count, minute v entilation, respiratory rate, breathing pattern and blood pressure wer e measured according to the following time schedule: pre-dialysis (tim e 0), and at 15, 30, 60, 120, 180, 240 min thereafter. Results showed that, with the use of cuprammonium dialyser, the WBC count dropped imm ediately and reached the nadir 15 min after haemodialysis. Thereafter, it recovered and overshot the pre-dialysis values until the end of di alysis. The bicarbonate dialysate indeed resulted in rapid and signifi cant metabolic alkalosis. However, no decrease of PaO2 occurred throug hout haemodialysis. The tidal volume, minute ventilation and breathing pattern remained stable during haemodialysis. We conclude that neithe r dialysis-induced alveolar hypoventilation nor arterial hypoxaemia de veloped during bicarbonate dialysis in patients mechanically ventilate d with the pressure support ventilation.