This study aimed to assess the impact of specific analgesic modalities on overall patient recovery, assessing post-operative length of stay, commencement of oral diet, complications and amount of opioids given post-operatively, for patients who underwent open hepato-pancreato-biliary surgery.
Due to the common adverse effects of copious systemic opioids, such as respiratory depression, efforts have been made to develop peri-operative analgesia which minimizes patient exposure to intravenous opioid pain relief. The development of epidural analgesia has been shown to reduce these risks [10], but isn’t without its own drawbacks, such as; intensive monitoring, high rates of medical intervention, ineffective analgesia, high failure rates (~ 30%) and post-operative hypotension [13].
Length of stay
A clear indicator of the rate of post-operative recovery was that of length of patient stay, both in HDU and overall. Our results highlight that there is no difference in the length of HDU stay between the WI-SP, WI-PCA or EP groups. This is in concordance with other studies in the literature, that show despite WI patients requiring less intensive monitoring than EP patients, HDU length of stay (days) was not significantly different (mean 1.3 vs 1.8, respectively) in patients undergoing liver resection [14].
Furthermore, our results show the overall length of stay did not differ between WI or EP arms; suggesting one modality does not confer an advantage with regards to overall post-operative recovery. This finding has been compounded by some studies found in the literature yet is contrasted to others. One RCT found there was no difference overall length of stay between WI or EP groups for patients undergoing liver resection [14], whereas another RCT found there was a reduced length of stay (days) in continuous wound infusion patients compared to those with epidural analgesia (4.5 and 6, respectively {p = 0.044}) [5].
Commencing oral diet
Post-operative ileus is often an inevitable consequence of surgery and an undesirable effect that is further compounded by excessive use of intravenous opioids [15].
One particular study found that the use of thoracic epidural analgesia (TEA) accelerated GI motility post-operatively compared with IV PCA, with differences more pronounced on post-operative day (POD) 3 [15]. Our analysis of post-operative eating and drinking again found there to be no significant difference between the WI-SP, WI-PCA or EP groups with respect to time taken to begin oral diet. These data suggest no difference in rate or return to normal GI function (an important requirement for patient discharge) between aforementioned analgesic modalities.
Additional opioids & pain management
Reducing post-operative pain is paramount in optimizing patient recovery and maximizing comfort during their hospital stay. Other studies in the literature have mainly used subjective pain scales to assess the efficacy of analgesic modalities [5, 14], but the retrospective nature of this study meant this information was unobtainable. Instead, we collected objective data based on amount of oral and intravenous opioids given to patients on a PRN basis, which found insignificant differences between the WI and EP groups in the amount of oral opioids taken post-operatively.
Although one particular systematic review of RCTs found wound catheters to provide improved analgesia [7], other literature looking at subjective pain scores have found epidural analgesia to be superior to continuous wound infusion on each day post-op [5, 14]. Nonetheless, even if this was the case with the patient data analyzed in this study, it did not translate into a significant oral opioid consumption in the WI group.
Further to oral opioids, the amount of IV morphine sulphate (PCA) administered between each group was compared. The use of IV PCA in patients with an epidural catheter has previously been defined as epidural failure [16]. From our data set, 24% (n = 18) of EP patients received PCA, which is in concordance with previously documented EP failure rates of 20–30% [14, 16, 17]. Although insignificant, the median amount of IV morphine sulphate administered to the EP group was higher than in the WI group (WI-SP and WI-PCA).
Overall complications
Using the Clavien-Dindo classification of post-operative complications, most patients in both the WI and EP groups had only class 1 complications, followed by class II. Of the class I complications, neither arm had patients that received fluid boluses due to post-operative hypotension, nor had respiratory depression. In contrast to this, other studies in the literature have found more complications in patients receiving epidural analgesia compared to wound-infusion groups, with one RCT showing a significant difference in vasopressor requirement on POD 0 (p = 0.001) and 1 (p = 0.021) in EP patients when compared with WI patients [14]. Similarly, a non-comparative study looked at the rate of hypofunction (inadequate pain relief) and hyper-function (hypotension or oliguria) of EP patients after pancreatectomies [16], finding hypofunction in 35% and Hyperfunction in 14% (combined complication rate of 49%) [16].
As 69% (n = 24/35) of the WI patients analyzed received a pre-operative spinal injection, it is important to compare both the efficacy and complications of epidural and spinal analgesia. A retrospective study analyzing post-op complications after open HPB surgery showed that of 51 patients receiving epidural analgesia, 41% (n = 21) experienced post-operative hypotension, compared 9% (n = 7/79) of patients receiving intrathecal morphine [11]. Furthermore, the quality of intrathecal morphine (ITM) was found to be noninferior to EP, with reduced hospital stay and favourable cost [13]. It has also been found that the efficacy of analgesia produced via spinal injection is superior to IV PCA alone, while concurrently reducing IV morphine consumption [11]. In our data set, although not significant (p = 0.137), the median IV morphine administered in the EP group was greater than that for the WI group overall, despite every patient within the WI arm receiving IV PCA.