Study designs of evaluations included in the review
Controlled trials, case reports and case series were eligible for inclusion in the review. The included studies were randomised controlled trials (RCTs), case series and case reports.
Specific interventions included in the review
Studies that evaluated MB were eligible for inclusion. The controlled studies evaluated different MB regimens and compared these regimens with an isotonic saline control; one controlled study administered vasopressors before MB, the other did not. The MB regimens evaluated were a 2 mg/kg bolus over 15 minutes followed by infusion at increasing rates from 0.25 to 2 mg/hour, and a 0.5 mg/kg per hour infusion over 6 hours. The observational studies also used different MB regimens; most used boluses of 1 to 4 mg/kg over 10 to 60 minutes.
Participants included in the review
Studies of patients aged 16 years or older with any of the following conditions were eligible for inclusion: sepsis defined as the presence of a systemic inflammatory response syndrome with demonstrated infection; septic shock defined by hypotension (systolic blood pressure <90 mmHg), and signs of tissue hypoperfusion (oliguria, arterial lactate >2.5 mmol/L); refractory septic shock (arterial hypotension persisting despite fluid administration and concurrent intravenous infusion of two or more vasoactive drugs for 1 hour).
Outcomes assessed in the review
Studies reporting haemodynamic variables or mortality rates were eligible for inclusion. The following outcomes were reported in the review: mean arterial pressure, mean pulmonary artery pressure, pulmonary vascular resistance, systemic vascular resistance, stroke volume, left-ventricular stroke work indices, oxygen delivery, requirements for vasopressors, survival rates at 28 days and adverse effects.
How were decisions on the relevance of primary studies made?
Two reviewers independently selected studies and agreed on the eligibility of all of the included studies.