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Page 2 of 7 Aslam et al. Mini-invasive Surg 2018;2:10 I http://dx.doi.org/10.20517/2574-1225.2017.42

INTRODUCTION
Intra-operative cardiac output (CO) monitoring facilitates goal-directed intra operative fluid therapy
(GDFT), a constituent of enhanced recovery pathways, which using a series of pre-, intra-and post-operative
[1]
guidelines , has been shown to improve patient recovery after major surgery. These programmes have been
[2-8]
shown to reduce the length of hospital stay, readmissions, and 30-day morbidity .
Intra-operative fluid administration is important in preventing hypovolaemia and its complications
including hypo-perfusion, impaired wound healing, anastomotic leak [9,10] and a systemic inflammatory
[2]
response , but there has been much debate in the literature about which intra-operative fluid (IOF) regimen
is best for patients undergoing both open and laparoscopic colorectal surgery, with many advocating
restrictive, more liberal or goal-directed fluid regimens with the aim of improving patient outcomes.

Restrictive regimens have been shown to be advantageous, reducing post-operative complications [11-15] ,
whereas liberal fluid administration has been associated with fluid overload and complications such as
a reduction in gut motility, mucosal oedema and an increased risk of anastomotic breakdown [16,17] . It is
also associated with pulmonary oedema and cardiac dysrhythmias [15,18-20] . GDFT aims to use dynamic
measurements of cardiac output to guide IOF administration to maintain a “zero fluid balance” and thus
reduce complications associated with inappropriate peri-operative fluid administration.

GDFT is achieved by monitoring cardiac output through various techniques, including the gold standard
- pulmonary artery catheter-based thermodilution, but this is an invasive procedure associated with
[21]
complications such as perforation of the pulmonary artery . Vital sign measurements such as blood
pressure and heart rate are not adequately specific or sensitive to guide fluid administration. Central venous
pressure (CVP) monitoring has also been used, but this is limited in colorectal surgery where the patient is
in the Trendelenburg position, creating a falsely elevated CVP by raising intrathoracic pressure, and has been
[22]
shown to be an ineffective guide for IOF therapy . Other techniques of continuous CO monitoring include
oesophageal Doppler (CardioQ, Deltex Medical Ltd, Chichester, UK) and arterial pressure (AP) waveform
analysis (LiDCO, LiDCO Ltd, Cambridge, UK) amongst others [23,24] .

Although there are many studies assessing the value of restrictive or liberal fluid regimens, further
investigation into the role of GDFT and CO monitoring in intraoperative fluid administration and its role on
patient outcomes is needed.

The aim of this study was to compare the surgical outcome measures between 2 groups of patients (those
who received intra-operative CO monitoring using the oesophageal Doppler or LiDCO and those who had
no intraoperative CO monitoring) who underwent elective colorectal surgery in an enhanced recovery
programme.

METHODS
Data was prospectively collected over a 5-year period (March 2010 - Feb 2015) for patients undergoing
elective colorectal surgery in a single surgeon’s practice. Data collection and analysis were performed by two
observers. Surgical outcome measures included 30- and 90-day mortality, morbidity, readmission, length of
hospital stay (LOS) and admission to a high level care facility [intensive care unit (ICU) or high dependency
unit (HDU)]. With the introduction of intra-operative cardiac output monitoring with either oesophageal
Doppler or LiDCO as a standard of care in patients on the ERAS pathways at the end of 2013, we compared
outcomes to those where no intra-operative cardiac output monitoring was used prior to this time. All
the patients were cared for on the enhanced recovery after surgery (ERAS) pathways. Statistical analysis
and inter-group comparisons were made using the Mann-Whitney U test. A P-value of < 0.05 was deemed
statistically significant.