In vivo catecholamine extraction during continuous hemodiafiltration in inotrope-dependent patients

Many critically ill patients require inotropic or vasopressor support to maintain adequate oxygen delivery. Removal of catecholamines by continuous hemodiafiltration (CHD) could alter exogenous catecholamine requirements. The authors have studied hemodynamic state, catecholamine clearances, and catecholamine requirements in 12 critically ill patients (mean APACHE II score, 24.5) receiving CHD. Hemodynamic parameters were assessed before CHD initiation, and at 4 and 24 hours of therapy. Simultaneous determinations of serum and ultradiafiltrate dopamine (D), norepinephrine (NE), and epinephrine (E) concentrations were obtained. There were no significant changes in any of many hemodynamic parameters measured during CHD. Mean catecholamine requirements were not altered by CHD. Plasma catecholamine levels were not significantly affected by CHD (mean values at 0, 4, and 24 hours: D: 10,801, 12,056, and 8,797 pg/ml; NE: 1124, 566, and 926 pg/ml; E: 1,420, 1,383, and 843 pg/ml). Catecholamine clearances from CHD (D:43.7 ml/min; NE: 43.5 ml/min; and E: 46.6 ml/min) resulted in daily excretion of only 379 micrograms D, 32.9 micrograms NE, and 37.2 micrograms E. Clearances of catecholamines by CHD represented a daily loss of less than 0.1% of the administered load. In conclusion, although CHD can remove circulating catecholamines, cumulative daily catecholamine extraction is minimal in pharmacologic terms, and has no impact on hemodynamic status.