Trial Information

Prospective, Double-Blinded, Randomised Controlled Trial of Doppler-Optimised Fluid Balance in Elective Colectomy Within an ERAS Protocol

Until very recently, modern perioperative fluid management has involved routine
administration of large quantities of fluids during major surgical procedures, typically
causing a weight increase of 3-6 kg in the early post-operative period.Several factors,
including concern about preoperative dehydration, attempts to support the circulation and
cardiac function after general and regional anaesthesia, prevention of blood transfusion and
maintenance of adequate kidney perfusion have historically lead to excess perioperative
fluid administration.

However administration of excess fluid has been shown to contribute to postoperative
morbidity. It increases demand on the heart and may adversely affect postoperative cardiac
function. It may also lead to increased pulmonary complications. Fluid overload may lead to
oedema of the gastrointestinal tract and hence contribute to post-operative gastrointestinal
paralysis, bacterial translocation and sepsis. Excess fluid also has been shown to decrease
tissue oxygen tension with potential deleterious effects on anastomotic and wound healing.

Therefore, current best practice has centred on fluid restriction peri-operatively with an
increased focus on the intraoperative fluid regimen. Since hypovolaemia is also associated
with a myriad of adverse outcomes, a balanced perioperative intravenous fluid regimen
focussing on tissue perfusion is thought to be optimal. By using the Oesophageal Doppler
Monitor (ODM) as a means to non-invasively estimate intra-operative cardiac output,
significant improvements in outcome have been observed in patients undergoing major
orthopaedic and cardiac procedures. Previous studies in patients undergoing major abdominal
surgery have demonstrated that goal-directed intraoperative fluid administration using ODM
may result in improved outcomes such as reduced number of critical care admissions, reduced
hospital stay and overall decreased morbidity.

In the broader context of perioperative care in colonic surgery, recent developments have
included Enhanced Recovery After Surgery (ERAS) programmes- a combination of various
evidence-based strategies implemented together as part of a standardised protocol to
synergistically decrease post-operative fatigue and improve outcomes. These strategies
include preoperative counselling, avoidance of mechanical bowel preparation, pre-operative
carbohydrate loading, perioperative high-flow oxygen therapy, mid-thoracic epidural
analgesia, avoidance of parenteral opioids and routine wound drainage, use of short or
transverse incisions, early mobilisation, early feeding and a balanced analgesia regiment.
ERAS protocols are also ideal for well-designed clinical trials as they provide a template
to trial new interventions on the background of an otherwise homogenous, optimised
perioperative care programme. An ERAS programme has been implemented and prospectively
evaluated at Manukau Surgical Centre, Middlemore Hospital in Auckland.

In a recently published systematic review, we identified that a major short-coming of the
literature in this field is the non-standardised nature of peri-operative management of the
patients in these studies. Although fluid management was optimised, the other aspects of
care were not optimised or even standardised, introducing the risk of significant
confounding. Furthermore, none have explored the role of fluid management on post-operative
functional recovery- an important metric of patient-relevant outcomes evaluating recovery
beyond physiological and clinical parameters. Furthermore, none of the published ERAS
programmes have used ODM as part of their peri-operative strategies. Consequently, the true
impact of optimised fluid therapy within an environment of current best-practice (ERAS) is
unknown.

Methods Research Design We will conduct a double-blinded, randomised controlled trial of ODM
versus fluid restriction (current best-practice) in patients undergoing colonic surgery
within our ERAS programme to determine whether individualising fluid administration enhances
post-operative recovery, thereby improving patient outcomes.

Sample Size:

To detect a 20% improvement in recovery as measured by the Surgical recovery Score at Day 7
(based on data from our previous work), we will require 37 patients in each arm (α= 0.05, β=
0.8) Therefore, we shall aim to recruit 80 patients anticipating for possible drop-outs.

Patients will be consented and then randomised by computer generated random numbers and the
opaque envelope method. All Patients will have an oesophageal probe inserted with readings
not available to the anaesthetist for patients in the control group (the screen will be
covered). At the commencement of anaesthesia, the patient will be randomised to receive
fluid management optimised by ODM data or by standard parameters. The patients, surgeons and
investigators will be blinded to the intervention. The anaesthetists will use a validated
protocol for the treatment group. Measurements of cardiac indices (Cardiac Output, Aortic
Flow Rate) from the ODM will be noted intraoperatively. The Oesophageal probe shall be
removed at the end of surgery prior to the patient waking up. All other aspects of
perioperative care will be according to our previously developed ERAS programme.