Haemodynamic impact of a slower pump speed at start of continuous renal replacement therapy in critically ill adults with acute kidney injury: A prospective before-and-after study

Background and Objective: Patients are at risk of haemodynamic instability when starting continuous renal replacement therapy (CRRT). Methods: We compared data for ‘routine-protocol’ pump speed increases of 50 ml/min over 1–4 min with ‘slower’ increases of 20–50 ml/min over 3–10 min to achieve an operating blood flow of 200 ml/min. Results: We studied 21 routine and 20 slower CRRT starts. ‘Routine protocol’ starts reached the target pump speed more quickly than the slower CRRT start (p < 0.05). Heart rate was higher in the routine group compared to the slower group at baseline (p < 0.01) and remained so throughout. There were no significant changes in central venous pressure or mean arterial pressure, and no episodes of hypotension or hypertension, in either group, or in the subset of 17 CRRT starts in vasopressor-dependent patients. Conclusion: We cannot recommend a slower pump speed start based on our findings, but advocate for close haemodynamic monitoring, as haemodynamic changes in individual patients cannot be predicted in advance.