Goal‑directed fluid restriction during brain surgery: a prospective randomized controlled trial

  • Luo J, Xue J, Liu J, Liu B, Liu L, Chen G.
  • Ann Intensive Care. 2017 Dec;7(1):16.

This Chinese randomised controlled study explores the impact that a goal-directed fluid restriction (GDFR) protocol had on outcomes during anaesthesia for brain surgery. The study comprised a total of 145 patients. Findings showed that those in the GDFR arm of the trial received less crystalloid and less colloid; they had shorter ICU stays, lower costs and fewer complications, although overall hospital length of stay and 30-day mortality were not significantly different.

Perioperative fluid administration has been demonstrated to be a major determinant of surgical outcomes. In some contexts, evidence for fluid titration based on physiological parameters has been shown to be beneficial for patients undergoing major procedures. Brain surgery represents a particular challenge in this domain, as there is a precise balance to be struck between the complications of inadequate fluid administration (hypovolaemia related: acute renal failure, myocardial infarction, cerebral ischaemia), and excessive fluid administration (overload related: cerebral oedema, peripheral tissue oedema). With that in mind, the investigators developed a protocol centred around physiological parameters aiming for a minimal required maintenance fluid, with colloid boluses as indicated by their protocol.

To this end, the investigators recruited 150 high-risk patients who were undergoing elective craniotomy for tumour resection, abscess, or intracranial aneurysm. They were randomised into a control and a treatment arm, the treatment arm was placed on a GDFR protocol. The protocol comprised a maintenance infusion of crystalloid (3 ml/kg/h), with a 200 ml colloid bolus in the case of systemic hypotension with reduced cardiac parameters (stroke volume variation and cardiac index) over the perioperative period. There were also recommendations for administration of vasopressors and ionotropes. The management of the control arm was left to the discretion of the individual anaesthetic team.  The primary outcome measured was ICU length of stay; secondary outcomes included: total fluid infused, post-operative complications at day 30, morbidity at day 30, mortality at day 30, hospital length of stay and costs.

There were 150 patients randomised, of whom five dropped out, leaving 73 in the GDFR arm and 72 in the control arm. The groups were comparable in demographic and operation parameters. The GDFR group was noted to receive significantly less colloid (p=0.021) and crystalloid (p<0.001) per kg per hour. Overall ICU stay was significantly shorter in the GDFR group (3 days [Interquartile range – IQR 1–5] versus 6 days [IQR 3–11], p=0.001), predictably resulting in ICU costs being significantly lower (p=0.037). There were fewer total complications in the GDFR group (46 versus 99; p=0.034), and fewer patients who experienced a post-operative complication in the GDFR group (14 versus 25; p=0.0034). Mortality and total hospital costs were also lower in the GDFR group, although this did not meet statistical significance.

The findings from this study suggest that in high-risk patients undergoing elective brain surgery, using a GDFR strategy results in less fluid being infused, fewer post-operative complications, and a shorter ICU stay. In some settings, using a goal-directed approach to fluid management has had conflicting evidence; in the surgical setting, meta-analysis has suggested an overall reduction in post-operative morbidity – in keeping with the findings of this study. The authors note that a ‘U-shaped’ relationship has been described between fluid volumes and outcomes post-surgery; the goal of this intervention was to rationalise the volume and type of fluid administered. There is a temptation, particularly with regard to brain surgery, to keep patients dry in order to minimise cerebral oedema; as a result, stroke volume variation was used as a parameter in this case – although the authors note that their chosen values were somewhat arbitrary, and may benefit from further investigation. The fact that less fluid was administered, but patients did not develop more hypovolaemia-related complications is a point in favour of this study. It is limited as it is a single centre trial, and focussed on high-risk patients, so extrapolation to other settings and lower risk patients may be difficult.

A recent large scale meta-analysis provided clear evidence against early goal-directed fluid therapy in sepsis; yet in some settings there is evidence that a goal-directed approach may prove to be very useful. Brain surgery, as discussed above, is an area where minimal necessary fluid administration can prove beneficial, this study provides a basis for wider investigation and optimisation of fluid protocols in this setting.

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