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RCTs

RCTs

A number of Randomized Controlled Trials (RCTs) have been conducted using the EDM to guide fluid management during surgery. See below for a summary of each, or the [Library] for a list of references.

Pillai, 2011 Summary

Clinical Application: Intraoperative

This double-blinded, randomized controlled trial compared routine intraoperative fluid management (fluids administered at the discretion of the anesthetist) with or without additional fluid guided by esophageal Doppler monitoring (EDM).

Protocol

Sixty six patients undergoing radial cystectomy were randomly allocated into either the control or intervention group. Both groups received fluid management at the discretion of the anesthetist, however, the intervention group also received additional colloid guided by EDM. Outcome measures included markers of gastrointestinal morbidity, postoperative nausea and vomiting, wound infection, and intraoperative fluid volumes.

Results

The intervention patients experienced less gastrointestinal morbidity; the number of patients experiencing ileus was reduced from 53% to 22% (P<0.001), the time flatus was reduced from 5.36 to 3.55 days (P<0.01), and the mean time to bowels opening was reduced from 9.79 to 6.53 days (P=0.02).

Postoperative nausea and vomiting (PONV) were significantly lower in the intervention group. Only 9% of the intervention patients experienced PONV at 24 hours postoperatively (vs. 32% of the control patients; P<0.01). At 48 hours postoperatively, 3% of the intervention and 38% of the control patients experienced PONV (P<0.0001). Both superficial and deep wound infections were also lower in the intervention group (6%) vs. the control (29%), P<0.01.

Mean length of hospital stay was reduced (non-significantly) by 4 days in the intervention patients (18 days vs. 22 days [control], P=0.12).

The intervention patients received more intraoperative fluid overall when compared with the control patients (0.23 mL/kg/min vs. 0.19 mL/kg/min; P<0.01). However, when total fluid administered was subdivided into that given during each hour of surgery, the volume administered was only different in the first hour of the procedure. During this time, the intervention group received ~50% more fluid than the control group (21 mL/kg vs. 14 mL/kg; P=0.0001).

Commentary

This study demonstrates that using the EDM to guide fluid management during surgery significantly improves patient outcome when compared to fluid management guided by the anesthetist alone.

The patients in this study who had additional fluid management guided by the esophageal Doppler device, experienced less gastrointestinal morbidity, less postoperative nausea and vomiting, and less wound infections. These findings are comparable with previous randomised controlled trials that have used EDM to guide intraoperative fluid management, and demonstrated reductions in postoperative complications and length of hospital stay when compared with traditional care [1-6].

An interesting observation from this study is that the only intraoperative period where the intervention patients received more fluid than the control patients was in the first hour of surgery. This finding indicates that the important time for fluid administration during surgery may be early in the procedure, a concept supported by Noblett et al. [3]. Early fluid optimization ensures adequate circulating blood volume and may reduce the postoperative complications that can be attributed to hypovolemia.

References
  1. Gan, T.J.S., A.; Maroof, M.; el-Moalem, H.; Robertson, K. M.; Moretti, E.; Dwane, P.; Glass, P. S., Goal-directed intraoperative fluid administration reduces length of hospital stay after major surgery. Anesthesiology, 2002. 97(4): p. 820-6.
  2. Mythen, M.G.W., A. R., Perioperative plasma volume expansion reduces the incidence of gut mucosal hypoperfusion during cardiac surgery. Arch Surg, 1995. 130(4): p. 423-9.
  3. Noblett, S.E.S., C. P.; Shenton, B. K.; Horgan, A. F., Randomized clinical trial assessing the effect of Doppler-optimized fluid management on outcome after elective colorectal resection. Br J Surg, 2006. 93(9): p. 1069-76.
  4. Sinclair, S.J., S.; Singer, M., Intraoperative intravascular volume optimisation and length of hospital stay after repair of proximal femoral fracture: randomised controlled trial. BMJ, 1997. 315(7113): p. 909-12.
  5. Venn, R.S., A.; Richardson, P.; Poloniecki, J.; Grounds, M.; Newman, P., Randomized controlled trial to investigate influence of the fluid challenge on duration of hospital stay and perioperative morbidity in patients with hip fractures. Br J Anaesth, 2002. 88(1): p. 65-71.Wakeling, H.G.M., M. R.; Jenkins, C. S.; Woods, W. G.; Miles, W. F.; Barclay, G. R.; Fleming, S. C., Intraoperative oesophageal Doppler guided fluid management shortens postoperative hospital stay after major bowel surgery. Br J Anaesth, 2005. 95(5): p. 634-42.
  6. Wakeling, H.G.M., M. R.; Jenkins, C. S.; Woods, W. G.; Miles, W. F.; Barclay, G. R.; Fleming, S. C., Intraoperative oesophageal Doppler guided fluid management shortens postoperative hospital stay after major bowel surgery. Br J Anaesth, 2005. 95(5): p. 634-42.

Challand, 2012 Summary

Clinical Application: Intraoperative

This double-blinded controlled trial compared goal-directed therapy (GDT; using esophageal Doppler monitoring (EDM) for intraoperative fluid management with that of routine care.

Protocol

179 patients undergoing elective colorectal surgery underwent cardiopulmonary exercise testing prior to being categorized as aerobically ‘fit’ (anaerobic threshold >11 mL O2/kg/min; n=123) or ‘unfit’ (n=56). Within each fitness group, patients were randomly assigned to receive fluid management using GDT or based on routine care. Patients included those undergoing both open and laparoscopic procedures. Outcome measures included readiness for discharge, actual length of stay, and postoperative complications.

Results

There was no difference in the amount of maintenance fluid given to the GDT and control groups (mean: 3849 mL vs. 4010 mL respectively). Approximately 90% of this maintenance fluid was crystalloid, infused at ~17 mL/kg/h. The GDT group received on average an additional 1360 mL of colloid (in the form of 200 mL boluses to optimise stroke volume (SV)). The GDT and control groups were 4179 mL and 4062 mL respectively in positive fluid balance at end of the day of their surgical procedure.

Time to readiness for discharge (6.8 [GDT] vs. 4.9 days [control]; P=0.09) and actual length of hospital stay (8.8 vs. 6.7 days; P=0.09) tended to be longer in the GDT group. This difference in length of stay became significant when analysis was performed on the aerobically ‘fit’ patients only. There were no significant differences in other outcome parameters including, gastrointestinal morbidity, serious postoperative complications, critical care admission or mortality between the GDT and control groups.

Commentary

The authors conclude “Intraoperative SV optimization conferred no additional benefit over standard fluid therapy. In an aerobically fit subgroup of patients, GDT was associated with detrimental effects on the primary outcome.”

Limitations

The results from this study are at odds with the previously published randomized controlled trials that use EDM to guide fluid management. The reasons for this may be related to the following:

  • Large volumes of maintenance crystalloid were administered to both patient groups. The authors aimed to target 10 mL/kg/h, but actually gave 17 mL/kg/h, an amount much higher than the recommended maintenance crystalloid rates of <2 mL/kg/h [1]. These high volumes of fluid may have placed the patients at risk of fluid overload.
  • The double-blinded nature of the study meant that during the procedure the anesthetist (infusing the maintenance fluid) and the investigator (administering the colloid boluses) were unable to correspond with each other. Therefore, even once the patient had an optimized SV (as deemed by the ODM), the anesthetist may still have been infusing high levels of maintenance crystalloid.
  • The poor randomization of the groups resulted in the GDT group having: fewer bowel preparations but more preoperative crystalloid loading, more epidurals, more blood transfusions and fewer laparoscopic procedures. These factors may have biased the GDT group towards a longer length of stay.
Summary of Responses

This study has generated responses from readers and the authors themselves, some of these are summarised as follows:

  • “The EDM data were only available to the investigator, who could, according to the algorithm, give boluses of colloid until no further increase in SV was recorded. At this point they would give no further fluid. The anesthetist without this information would continue to give maintenance and other fluid they felt necessary…It seems the study design led to more fluid being given than might have been if the ODM data were visible to the an esthetist.” Rivers, 2012 [2]
  • “This study provides a surprising result…which is in contrast to the large body of available data supporting the use of GDT in open surgery and the NICE technology appraisal… It is hard to see from the data presented exactly what led to the delayed readiness for discharge as tolerance of diet, bowel movement, flatus passed, renal complications, and postoperative complications did not show any significant difference between the two groups… As with many studies, it raises more questions than it directly answers.” Isherwood, 2012 [3]
References
  1. Mythen, M.G.S., M.; Acheson, N.; Crawford, R.; Jones, K.; Kuper, M.; McGrath, J. S.; Horgan, A. F., Perioperative fluid management: Consensus statement from the enhanced recovery partnership. Perioperative Medicine, 2012. 1(2).
  2. Rivers, J., Intraoperative goal-directed fluid therapy in aerobically fit and unfit patients having major colorectal surgery. Br J Anaesth, 2012. 108(6): p. 1036; author reply 1037.
  3. Isherwood, P., Re: Randomized controlled trial of intraoperative goal-directed fluid therapy in aerobically fit and unfit patients having major colorectal surgery. Br J Anaesth, 2012. 108(6): p. 1036-7; author reply 1037.