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Page 2 of 12 Kumar et al. Mini-invasive Surg 2018;2:41 I http://dx.doi.org/10.20517/2574-1225.2018.49

pulse combined with release of humoral substances [such as prostaglandins, kinins, leukotrienes, IL-1 and
tumor necrosis factor (TNF)]. This phenomenon is amplified by factors including semi-starvation, infec-
[2]
tion and hemorrhage . The neural pathway is probably most important in releasing the classic endocrine
catabolic response, while associated release of humoral factors is important for the hyperthermic response,
[1,2]
changes in coagulation and fibrinolysis, immune function and capillary permeability . No wonder, atten-
uation of surgical stress response is dependent upon the technique of analgesia and afferent neural block-
[1]
ade with local anesthetic, with epidural being the most effective technique . The introduction of effective
neural blockade and use of epidural analgesia has been found to mitigate the metabolic response to surgi-
cal stress, but has a less important effect on inflammatory or immunologic responses. On the contrary,
minimally invasive surgery reduces the inflammatory response and immune suppression, while leaving the
[1]
metabolic response mostly unaltered .

Even though the concept of bundling perioperative treatments to improve outcomes was developed in the
early 90’ and known as “Fast-Track” surgery, the enhanced recovery after surgery (ERAS) protocol was de-
[3,4]
veloped in Europe in 2001 . This last involved a more comprehensive multidisciplinary and multimodal
approach with the main end-point of enhancing the quality of recovery by attenuating the perioperative
[4]
surgical stress and improving the response to stress rather than just accelerating the speed of recovery .
Initially employed in colorectal surgery, it led to tremendous improvement in patient outcomes follow-
ing surgery. This was later adopted by other surgical specialties including liver surgery. No wonder, many
[5]
recommendations pertaining to ERAS in liver surgery arise from the experience in colorectal surgery .
However, there has been an increased need to develop liver specific programs to optimize ERAS protocols
and outcome parameters given that features such as hepatic reserve evaluation, surgical complexity and
risk of post-hepatectomy liver failure are unique to liver surgery. Naturally, many strategies employed to
enhance recovery after liver surgery are similar to other surgical fields, including perioperative measures
[6]
as well as postoperative recovery standardization [Table 1]. After Mackay and O’Dwyer reported their
initial enhanced recovery protocols for liver resection, few ERAS protocols for liver surgery have been pub-
[7-9]
lished, and data is limited mostly to observational studies and few randomized controlled trials (RCT) .
In addition, there is scarce data comparing ERAS programs with conventional liver surgery protocols, and
[9]
meta-analyses including RCTs suffer from inadequate disclosure of randomization techniques . The sub-
jective nature of end points (i.e., time to flatus) and the heterogeneity in outcome measures between studies
lead to inherent imprecise data [i.e., length of stay (LOS), where the patient may be fit for discharge but stay
in hospital due to logistic reasons]. Primary surgeon experience, baseline patient characteristics and selec-
tion criteria may also significantly impact the validity of results. Hence, even though there is a growing
body of evidence in favor of ERAS application in liver surgery, further studies are required to determine
the most effective ERAS protocol for this particular field. The purpose of this review is to summarize the
current scientific evidence on the most important elements of an ERAS program in liver surgery and the
outcomes associated with the application of this protocol compared to traditional care.

KEY COMPONENTS OF ERAS PROTOCOLS IN LIVER SURGERY
Implementation of the complete set of traditional core elements of ERAS protocols is rarely seen in refer-
[10]
ral liver surgery centers . Although pre- and perioperative elements have a good adherence, compliance
[10]
is especially poor for the postoperative phase elements . This may be due to the fact that at least 7 out of
23 classical ERAS items validated for colorectal surgery have not been studied in liver surgery yet, and it is
[5]
currently unclear whether they can be extrapolated for liver surgery . However, some have been consid-
ered of outmost importance for liver surgery in recent meta-analyses and a consensus guideline from the
[5,9]
international ERAS Society . Specifically, pre- and intraoperative fluid restriction and no routine naso-
[9]
gastric tubes (NGTs) postoperatively have been considered significant for liver surgery . On the contrary,
elements such as preoperative oral mechanical bowel preparation and postoperative stimulation of bowel
[5]
movement are not considered indicated in liver surgery .