|
- dialysate produced by mixing a concentrated solution and purified water to
achieve desired electrolyte concentrations
- dialysate delivered to dialyzer at 300-500 ml/min while blood flow maintained
at 200-300 ml/min
- higher concentrations of Na (140-145 cf 130-140 mmol/L) should be used in
haemodynamically unstable patients or those at risk of disequilibrium syndrome
- hypotension occurs in approx 25% of patients
- acetate most commonly used dialysate buffer. May cause vasodilatation and
hypotension. Replace with bicarbonate in patients at risk of hypotension
- relies on removing fluid over relatively short period of time. If fluid
removal excessive (rate or volume) hypotension will result, in which case longer
period of dialysis at a lesser ultrafiltration rate should be used. Hypotension
is in part due to relatively high intracellular urea and hence shift of fluid
from ECF to ICF compartment
- toxin removal from poorly perfused organs suboptimal because of insufficient
time for tissue concentration to equilibrate with blood concentration. As a
result plasma urea concentration just after dialysis often 20-30% lower than
value 30-45 min later. Effect of swings in concentration unknown
Drug dosage
- molecules >500 D not removed using cuprophane membranes
- for smaller molecules extraction depends on urea clearance achieved during
procedure and duration of procedure
- for a number of drugs post dialysis redosing necessary (all drugs listed above
except ciprofloxacin and vancomycin)
| 
