Ketanserin Effects on Peripheral Temperature and Lactate (KoPTaL)

A high blood lactate and a high peripheral to central temperature difference (deltaT) are associated with a higher mortality in critically ill patients. Both measures are signs of a reduced microcirculatory bloodflow or vasoconstriction and are associated with shock. It is unknown which medication can best be used to improve deltaT and lactate clearance. Ketanserin is being used in the intensive care setting for decades to optimize circulatory parameters. Ketanserin is a serotonin type 2-receptor blocker (5-HT2). Blocking the 5-HT2 receptor with ketanserin can attenuate pathological vasoconstriction. In these ways ketanserin can reduce vasoconstriction and can improve the microcirculation. As a consequence, the enhanced blood flow in the skin will increase the peripheral temperature and decrease deltaT. At the same time an increased flow in the microcirculation may lead to a reduction in lactate production. Objective: To determine the effects of a continuous ketanserin infusion on peripheral temperature and lactate clearance in critically ill patients with either a high lactate or a high deltaT.

Rationale: A high blood lactate and a high peripheral to central temperature difference (deltaT) are associated with a higher mortality in critically ill patients. Both measures are signs of a reduced microcirculatory bloodflow or vasoconstriction and are associated with shock. On the other hand, it has not been shown yet that interventions leading to improvement of this temperature gap reduces mortality or improves any other outcome measurement. Moreover, it is unknown which medication can best be used to improve deltaT and lactate clearance. Ketanserin is being used in the intensive care setting for decades to optimize circulatory parameters. Ketanserin is a serotonin type 2-receptor blocker (5-HT2). Blocking the 5-HT2 receptor with ketanserin can attenuate pathological vasoconstriction. In these ways ketanserin can reduce vasoconstriction and can improve the microcirculation. As a consequence, the enhanced blood flow in the skin will increase the peripheral temperature and decrease deltaT. At the same time an increased flow in the microcirculation may lead to a reduction in lactate production. Objective: To determine the effects of a continuous ketanserin infusion on peripheral temperature and lactate clearance in critically ill patients with either a high lactate or a high deltaT. Study design: A multicentre double blind randomized controlled trial. Study population: All adult intensive care patients above 17 years old with a deltaT of >6°C with informed consent given by the patient or legal representative. Intervention (if applicable): The intervention is a continuous pump driven Ketanserin infusion of 0.75 ug/kg/min for eight hours. The control group will receive the same volume of glucose 5%. Main study parameters/endpoints: Change in DeltaT (measured per hour) Change in lactate (measured per 2 hours) Nature and extent of the burden and risks associated with participation, benefit and group relatedness: The risks of ketanserin infusion are limited but can be a QTc prolongation and a slight decrease in blood pressure. The study needs an arterial blood sample on inclusion, and after 2, 4, 6 and 8 hours of 1.5 ml each. In addition, a 6 ml blood sample at T=4 and T=8 hours.

Ketanserin is a serotonin type 2-receptor blocker (5-HT2). In normal endothelium, the 5-HT1 effects (vasodilation) are the most prominent [Dabire 1990]. In endothelium that is damaged, which is the case in sepsis, the 5HT2 effects (vasoconstriction) surpass the 5-HT1 effects. Blocking the 5-HT2 receptor with ketanserin can attenuate this pathological vasoconstriction. In addition, ketanserin has favourable α1-adrenergic blocking properties in the endothelium (vasodilation) that may further reverse the pathological vasoconstriction. In these ways ketanserin can reduce vasoconstriction and can improve the microcirculation.

The dose of 0.75 ug/kg/min is a dose that has been used frequently in critically ill patients. The concentration of the study drug infusion will be 40 mg/40 ml glucose 5%. The maximum dose however will be 4.5 mg per hour for patients with a weight more than 100 kg. The pre-filled 50 ml syringes will be filled with 40 ml of a solution containing 40 mg ketanserin or 0 mg ketanserin in glucose 5%. The minimum number of ketanserin vials (2 ml with 5 mg/ml) that are needed is 240 (40 mg = 4 vials per patient). Duration of intervention: 8 hours

Delta Temperature is calculated from the difference between central (rectal) and peripheral (forefoot) temperature

Lactate clearance is defined as :(Lactate (admission) - Lactate (8 hours))*100 / Lactate (admission) (Lactate (admission) - Lactate (8 hours))*100 / Lactate (admission) A lactate clearance of 10% or more is regarded as clinical relevant

Inclusion Criteria: DeltaTemperature greater that 6.0 °C. Age 18 years or older Admitted to the ICU for any reason Signed informed consent from the patient or legal representative Exclusion Criteria: Pregnancy No possibility to obtain informed consent QTc above 550 msec, Arrhythmias, including bradycardia defined as a heart rate below 50/min; 2nd and 3rd degree AV block; ventricular tachycardia Blood Potassium level < 3.5 mmol/l Blood Magnesium level <0.5 mmol/l Allergy for ketanserin DeltaT less than 6°C. Patients undergoing therapeutic hypothermia Patients admitted after cardiac arrest Patients admitted after cardiac surgery