Hemodynamic Effects of Dexmedetomidine in Septic Shock

The current treatment regimen of patients with septic shock requires a sufficient hemodynamic support aiming to preserve tissue oxygen requirements and perfusion. Therefore, aggressive fluid challenge and vasopressor agents play a pivotal role. To increase total peripheral resistance and preserve organ perfusion, a continuous infusion of catecholamines is often needed. Because sepsis is usually associated with adrenergic receptor and post-receptor abnormalities, the efficacy of such treatment regimens often gradually decreases over time, thereby complicating hemodynamic support. Experimental evidence suggest that α-2 agonists increase pressor responsiveness following lipopolysaccharide administration. This study will assess the effects of the sedation with dexmedetomidine (α-2 agonist) on norepinephrine requirements in patients with septic shock.

The present study was designed as a prospective study. All patients enrolled in the study will require norepinephrine to maintain MAP between 65 and 75 mmHg despite adequate volume resuscitation and will be sedated according to istitutional guidelines with propofol and remifentanyl. After 8 h had elapsed during stable hemodynamic conditions, an initial set of measurements will be obtained during the sedation with propofol and remifentanyl. This set of measurements will be considered as baseline. In the patients in which conventional sedation will be replaced by dexmedetomidine and remifentanyl, a second set of measurements will be obtained after 4 h had elapsed during stable conditions. A final set of mesurements will be obtained after another 8-h period in stable conditions after switcheing back again to propofol and remifentanyl, . During the observational period the dosage rate of norepinephrine will be adjusted to maintain the same threshold MAP of 65-75 mmHg All other medications were held constant.

Sedation with propofol and remifentanyl will be replaced by a sedation with dexmedetomidine and remifentanyl