Research

Norepinephrine weaning in septic shock patients by closed loop control based on fuzzy logic

Mehdi Merouani¹ , Bruno Guignard² , François Vincent³ , Stephen W Borron⁴ , Philippe Karoubi³ , Jean-Philippe Fosse³ , Yves Cohen³ , Christophe Clec'h³ , Eric Vicaut⁵ , Carole Marbeuf-Gueye⁶ , Frederic Lapostolle¹ and Frederic Adnet¹

¹Samu 93 – EA 3409, Université Paris 13, Hôpital Avicenne, Rue de Stalingrad, 93000 Bobigny, France

²Département d'Anesthésie et de Réanimation, Hôpital Ambroise Paré, Avenue Charles-de-Gaulle, 92100 Boulogne Billancourt, France

³Service de Réanimation, Hôpital Avicenne, Rue de Stalingrad, 93000 Bobigny, France

⁴Department of Surgery (Emergency Medicine), University of Texas Health Science Center at San Antonio, Medical Drive, San Antonio, TX 78229, USA

⁵Unité de Recherche Clinique, Hôpital Fernand Widal, Rue Ambroise Paré, 75475 Paris Cedex, France

⁶BioMoCeTi, UMR 7033, UFR SMBH, Université Paris 13, Rue Marcel Cachin, 93000 Bobigny, France

author email corresponding author email

Critical Care 2008, 12:R155doi:10.1186/cc7149

Published:	9 December 2008

See related commentary by Hazelzet, http://ccforum.com/content/13/1/116

Abstract

Introduction

The rate of weaning of vasopressors drugs is usually an empirical choice made by the treating in critically ill patients. We applied fuzzy logic principles to modify intravenous norepinephrine (noradrenaline) infusion rates during norepinephrine infusion in septic patients in order to reduce the duration of shock.

Methods

Septic patients were randomly assigned to norepinephrine infused either at the clinician's discretion (control group) or under closed-loop control based on fuzzy logic (fuzzy group). The infusion rate changed automatically after analysis of mean arterial pressure in the fuzzy group. The primary end-point was time to cessation of norepinephrine. The secondary end-points were 28-day survival, total amount of norepinephine infused and duration of mechanical ventilation.

Results

Nineteen patients were randomly assigned to fuzzy group and 20 to control group. Weaning of norepinephrine was achieved in 18 of the 20 control patients and in all 19 fuzzy group patients. Median (interquartile range) duration of shock was significantly shorter in the fuzzy group than in the control group (28.5 [20.5 to 42] hours versus 57.5 [43.7 to 117.5] hours; P < 0.0001). There was no significant difference in duration of mechanical ventilation or survival at 28 days between the two groups. The median (interquartile range) total amount of norepinephrine infused during shock was significantly lower in the fuzzy group than in the control group (0.6 [0.2 to 1.0] μg/kg versus 1.4 [0.6 to 2.7] μg/kg; P < 0.01).

Conclusions

Our study has shown a reduction in norepinephrine weaning duration in septic patients enrolled in the fuzzy group. We attribute this reduction to fuzzy control of norepinephrine infusion.

Trial registration

Trial registration: Clinicaltrials.gov NCT00763906.