Hemodynamic impact of the connection to continuous renal replacement therapy in critically ill children

Continuous renal replacement therapy (CRRT) is the treatment of choice for critically ill children with acute kidney injury. Hypotension after starting CRRT is frequent but very few studies have analyzed its incidence and clinical relevance.

A prospective, observational study was performed including critically ill children treated with CRRT between 2010 and 2014. Hemodynamic data and connection characteristics were collected before, during, and 60 min after CRRT circuit connection. Hypotension with the connection was defined as a decrease in > 20% of the mean arterial pressure from baseline or when intravenous fluid resuscitation or an increase in vasopressors was required.

One hundred sixty-one connections in 36 children (median age 18.8 months) were analyzed. Twenty-eight patients (77.8%) were in the postoperative period of cardiac surgery, 94% had mechanical ventilation, and 86.1% had vasopressors. The heparinized circuit priming solution was discarded in 8.7% and infused to the patient in 18% of the connections. The circuit was re-primed in the remaining 73.3% using albumin (79.3%), red blood cells (4.5%), or another crystalloid solution without heparin (16.2%). Hypotension occurred in 49.7% of the connections a median of 5 min after the beginning of the therapy. Fluid resuscitation was required in 38.5% and the dose of vasopressors was increased in 12.4% of the connections. There was no relationship between hypotension and age or weight. Re-priming the circuit with albumin reduced the incidence of hypotension from 71.4 to 44.6% (p = 0.004).

Hypotension after the connection to CRRT is very frequent in critically ill children. Re-priming the circuit with albumin could improve hemodynamics during connection.