Physiological changes after fluid bolus therapy in sepsis: a systematic review of contemporary data

Abstract

Fluid bolus therapy (FBT) is a standard of care in the management of the septic, hypotensive, tachycardic and/or oliguric patient. However, contemporary evidence for FBT improving patient-centred outcomes is scant. Moreover, its physiological effects in contemporary ICU environments and populations are poorly understood. Using three electronic databases, we identified all studies describing FBT between January 2010 and December 2013. We found 33 studies describing 41 boluses. No randomised controlled trials compared FBT with alternative interventions, such as vasopressors. The median fluid bolus was 500 ml (range 100 to 1,000 ml) administered over 30 minutes (range 10 to 60 minutes) and the most commonly administered fluid was 0.9% sodium chloride solution. In 19 studies, a predetermined physiological trigger initiated FBT. Although 17 studies describe the temporal course of physiological changes after FBT in 31 patient groups, only three studies describe the physiological changes at 60 minutes, and only one study beyond this point. No studies related the physiological changes after FBT with clinically relevant outcomes. There is a clear need for at least obtaining randomised controlled evidence for the physiological effects of FBT in patients with severe sepsis and septic shock beyond the period immediately after its administration.

Figure 1

Describing the concept of idealised fluid bolus therapy. (A) Diagram describing the key criteria defining the concept of a fluid bolus. (B) Diagram describing the idealised concept of fluid bolus therapy in critical care, including purpose, triggers, end-points and purported physiological effects of such resuscitation.

Figure 2

Electronic search strategy. Diagrammatic representation of the search strategy combining terms representing fluid resuscitation, sepsis and clinical studies, along with predetermined limitations.

Figure 3

Study selection. Flow diagram of the study selection process and detailed description of study exclusions. FBT, fluid bolus therapy.

Figure 4

Physiological effects of fluid bolus therapy over time. Multi-panel figure of the haemodynamic effects of fluid bolus therapy (FBT) as reported in studies with observation periods of 60 minutes or more. (A) Changes in heart rate over time. (B) Changes in cardiac index over time. (C) Changes in mean arterial pressure over time. (D) Changes in central venous pressure (CVP) over time. Each solid black line represents a patient group and the average physiological response to FBT over the observation period. Lines terminate when measurements were discontinued in the study from which the group was taken.