Bolus hypertonic or normal saline resuscitation in gram-negative sepsis: systemic and regional haemodynamic effects in sheep.

BACKGROUND

Fluid resuscitation with saline in severe sepsis is controversial. Hypertonic (3%) saline (HTS) may be superior to normal (0.9%) saline (NS).

OBJECTIVE

To compare the effects of HTS and NS on regional blood flow in sepsis.

DESIGN

Randomised controlled crossover large animal study.

SETTING

University physiology laboratory.

SUBJECTS

Seven merino cross ewes.

INTERVENTIONS

We implanted chronic flow probes around aorta, mesenteric, coronary and renal arteries. Sepsis was induced by the intravenous injection of 3 × 109 colonyforming units of live Escherichia coli. We randomised animals to three groups after onset of sepsis: observation (control), NS (1000 mL over 15 minutes) and HTS (300 mL over 15 minutes).

MAIN OUTCOME MEASURES

Continuously measured systemic haemodynamics, organ blood flows and markers of renal function for 210 minutes.

RESULTS

In septic sheep, bolus resuscitation with HTS had similar systemic haemodynamic effects as NS and both increased cardiac output and mesenteric blood flow during the first hour compared with control (P < 0.05). However, this effect dissipated after 60 minutes. These effects were mirrored by effects on mesenteric and coronary blood flow. In contrast, renal blood flow was not changed by either HTS or NS. HTS transiently increased total and mesenteric oxygen delivery (P < 0.05), while NS transiently decreased total and renal oxygen delivery. Urine output and creatinine clearance decreased with sepsis and only transiently increased with NS (P < 0.05) but not HTS.

CONCLUSIONS

In gram-negative sepsis, bolus resuscitation with HTS and NS have similar and transient systemic and regional haemodynamic effects, but no effects on renal perfusion and only short-lived effects on renal function. These findings challenge the physiological rationale for fluid bolus resuscitation in sepsis.