Abstract
Extracorporeal carbon dioxide removal (ECCO 2R) devices remove CO 2 directly from blood, facilitating ultraprotective ventilation or even providing an alternative to mechanical ventilation. However, ECCO 2R is not widely available, whereas dialysis is available in most intensive care units (ICUs). Prior attempts to provide ECCO 2R with dialysis, by removing CO 2 in the form of bicarbonate, have been plagued by metabolic acidosis. We hypothesized that bicarbonate dialysis is feasible, provided the plasma strong ion difference is maintained. We used a mathematical model to investigate the effects of bicarbonate removal on pH and CO 2 in plasma, and performed in-vitro experiments to test CO 2 removal using three dialysates with different bicarbonate concentrations (0, 16, and 32 mmol·L -1). Our modeling predicted a reduction in partial pressures of CO 2 (PCO 2) and increased pH with progressive lowering of plasma bicarbonate, provided strong ion difference and plasma proteins (A tot) were maintained. In our in-vitro experiments, total CO 2 removal, scaled up to an adult size filter, was highest with our dialysate containing no bicarbonate, where we removed the equivalent of 94 ml·min -1 (±3.0) of CO 2. Under the same conditions, our dialysate containing a conventional bicarbonate concentration (32 mmol·L -1) only removed 5 ml·min -1 (±4; p < 0.001). As predicted, pH increased following bicarbonate removal. Our data show that dialysis using low bicarbonate dialysates is feasible and results in a reduction in plasma PCO 2. When scaled up, to estimate equivalent CO 2 removal with an adult dialysis circuit, the amount removed competes with existing low-flow ECCO 2R devices.
Original language | English |
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Journal | ASAIO Journal |
Volume | 65 |
Issue number | 6 |
Pages (from-to) | 605-613 |
Number of pages | 9 |
ISSN | 1058-2916 |
DOIs | |
Publication status | Published - 1 Aug 2019 |
Keywords
- Dialysis
- Intensive care units
- Ventilation
- artificial
- Carbon dioxide removal
- CO2 removal
- Mechanical ventilation
- Metabolic acidosis
- Plasma protein
- Proof of concept
- respiration
- Carbon dioxide