The main purpose of this study is to determine the effects of controlling the heart rate of patients with septic shock using an intravenous medication called esmolol.
Septic shock is a leading cause of death around the world, with a mortality that often ranges 30-50% but in some locations may be even higher. Despite advances in critical care medicine over the last several decades, few therapeutic interventions have demonstrated mortality benefit in this population besides antimicrobial medications, intravenous fluids, and controlling the source of the infection; multiple agents which at one time showed promise have ultimately failed to deliver meaningful clinical benefit. As such, there is an ongoing need to identify therapeutic interventions which can modify the course of disease for these patients. Septic shock is traditionally characterized by a hyperdynamic hemodynamic profile with a high cardiac output (CO) and low systemic vascular resistance (SVR) in association with excessive catecholamine stimulation. Tachycardia is a common finding in septic shock as an early compensatory mechanism to increase cardiac output in the setting of low SVR. Often tachycardia persists beyond the initial stages of septic shock, and has been associated with restricted diastolic ventricular filling, increased oxygen requirements, and tachycardia-induced cardiomyopathy, as well as myocardial depression, immunosuppression, and direct myocyte toxicity via calcium overload. Generally, clinical practice has been to avoid trying to control the tachycardic response for fear of worsening cardiac output and causing cardiovascular collapse. However, a recent single center randomized trial of the intravenous beta-1 adrenoreceptor antagonist esmolol demonstrated that control of heart rate to a more 'normal' range was safe, well-tolerated, and appeared beneficial, with a 30% reduction in mortality found in this trial. While an intriguing concept with results that appear promising, further investigation among an ICU cohort in the United States is necessary before the administration of beta-blockade therapy to a patient in septic shock should be implemented in routine clinical practice. We hypothesize that the provision of esmolol to patients in vasopressor-dependent septic shock with tachycardia will lower the heart rate, thereby improving diastolic filling time and improving cardiac output, resulting in a reduction in need for vasopressor support. To test our hypothesis, we are conducting a Phase II randomized trial to determine if esmolol decreases vasopressor requirements (primary endpoint) and alters the inflammatory cascade as well as oxygen consumption in patients with septic shock (secondary endpoints).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
40
Beth Israel Deaconess Medical Center
Boston, Massachusetts, United States
Need for Vasopressor Support, Measured as Mean Norepinephrine Equivalent Dose (mcg/kg/Min), at 6hr Time Point
The primary endpoint will be mean norepinephrine equivalent dose (mcg/kg/min) at 6 hours after onset of study drug. For the vasopressor vasopressin, the dose of vasopressin was multiplied by 2.5 in order to create a norepinephrine equivalent dose. For the vasopressor phenylephrine, the dose of phenylephrine was divided by 10 in order to create a norepinephrine equivalent dose.
Time frame: 6 hours
Overall Need for Vasopressor Support
While the primary endpoint will be mean norepinephrine dose at 6h, we will also measure mean vasopressor dose in groups at 12h and 24h.
Time frame: 12 and 24 hours
Heart Rates Between Groups
We will measure median heart rate at the 6 and 12h time points.
Time frame: 6 and 12 hours
Time to Shock Reversal
Time to shock reversal (cessation of all vasopressors for at least 12h).
Time frame: Duration of hospitalization, limit 180 days
Lactate
Median percent change from baseline lactate measured at the 6, 12, and 24 hour time points after study initiation between groups. Percent change was calculated by subtracting the later lactate from the baseline lactate and dividing the difference by the baseline lactate (i.e. (baseline lactate - 6h lactate)/baseline lactate).
Time frame: 6, 12, and 24 hours
Oxygen Consumption (VO2)
To analyze the difference in oxygen consumption between groups at 12 hours, 24 hours and over time for patients who were on mechanical ventilation at enrollment, VO2 measurements were compared (standardized by bodyweight in kilograms) over time (recorded every minute from the time of study drug administration over a period of at least 24 hours) between groups using mixed linear model accounting for repeated measures. Using an unadjusted model, mean differences at 12 hours, 24 hours and for differences in the overall trend over time were tested.
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Time frame: 12 and 24 hours
Interleukin-4
To characterize effects of esmolol on inflammatory markers in patients with vasopressor-dependent septic shock, we compared log-transformed values of interleukin-4 at 12 and 24 hours and over time between groups using mixed linear model accounting for repeated measures and adjusting for pre-intervention levels.
Time frame: 12 and 24 hours
Interleukin-6
To characterize effects of esmolol on inflammatory markers in patients with vasopressor-dependent septic shock, we compared log-transformed values of interleukin-6 at 12 and 24 hours and over time between groups using mixed linear model accounting for repeated measures and adjusting for pre-intervention levels.
Time frame: 12 and 24 hours
Interleukin-10
To characterize effects of esmolol on inflammatory markers in patients with vasopressor-dependent septic shock, we compared log-transformed values of interleukin-10 at 12 and 24 hours and over time between groups using mixed linear model accounting for repeated measures and adjusting for pre-intervention levels.
Time frame: 12 and 24 hours
TNF-alpha
To characterize effects of esmolol on inflammatory markers in patients with vasopressor-dependent septic shock, we compared log-transformed values of TNF-alpha at 12 and 24 hours and over time between groups using mixed linear model accounting for repeated measures and adjusting for pre-intervention levels.
Time frame: 12 and 24 hours
C-reactive Protein
To characterize effects of esmolol on inflammatory markers in patients with vasopressor-dependent septic shock, we compared log-transformed values of C-reactive protein at 12 and 24 hours and over time between groups using mixed linear model accounting for repeated measures and adjusting for pre-intervention levels.
Time frame: 12 and 24 hours