Incorporation of an intercostal catheter into a multimodal analgesic strategy for uniportal video-assisted thoracoscopic surgery: a feasibility study

Pain management in thoracic surgery is essential to promote early recovery and avoid complications like urinary retention, atelectasis and pneumonia. For pain control after thoracotomy, thoracic epidural analgesia (TEA) and paravertebral blocks (PVB) have been regarded as the gold standards [1]. In recent years, owing to the success of minimally invasive thoracic surgery, there has been an increasing adoption of surgical techniques like uniportal video-assisted thoracoscopic surgery (UVATS). However, the optimal postoperative analgesia after UVATS is still undetermined.

Studies have demonstrated that both TEA and PVB provide adequate analgesic effect after major thoracic surgery, but the former may be associated with adverse effects such as urinary retention and hypotension [2‐5]. Failure rates of TEA placement have also been reported to be up to 30% [6, 7]. In recent years, the placement of an intercostal catheter (ICC) has been explored as a regional analgesic option. The multihole catheter can be inserted at the uniport incision in an atraumatic manner under direct thoracoscopic vision. When connected to a single-use elastomeric pump, the catheter can deliver an anaesthetic continuously and independently. The pump is available in a variety of volumes. Depending on the model, the flow rate of the anaesthetic can be fixed or titrated with an attached controller. The ICC has been shown to achieve good postoperative pain control in abdominal and orthopaedic surgeries [8‐10], but evidence on its utility in thoracic surgery is mixed [11‐13].

There has been a shift away from systemic opioids to regional options for pain management after thoracic surgery [14, 15]. This is especially relevant in guidelines promoting the use of opioid-sparing multimodal analgesia from evidence-based perioperative care protocols such as the Enhanced Recovery After Surgery (ERAS®) pathway [16]. The objective of this feasibility study was to evaluate our hypothesis that utilizing an ICC as part of a multimodal analgesic strategy would provide adequate pain relief after UVATS, while reducing the usage of opioids.

Table 1 illustrates the characteristics of the 26 patients who received the ICC since we first started using it in March 2016. Majority of the patients were ASA 2 or higher, and had 3 or more comorbidities. Most of our patients underwent major resections for tumours and lobectomy was most commonly performed. Mediastinal lymph node dissection was routinely performed in resections of primary lung malignancies. The total duration of surgery was 185.4 ± 81.4 min. A single chest drain was inserted in 25 patients (96.2%) and only one patient received 2 chest drains due to bilateral pleural effusions. None of our patients required extension of the UVATS incision to remove the resected specimen.

Table 2 shows the mean pain scores over the first 5 postoperative days. In addition to receiving the standardised analgesic regimen (single-shot intercostal block and regular paracetamol) and the ICC, a total of 9 patients (34.6%) required PCA and 16 patients (61.6%) required a combination of rescue analgesics. 1 patient (3.8%) only received the single-shot intercostal block and ICC, and did not require regular paracetamol or any other rescue analgesics. Of those who were prescribed PCA, 7 of them used boluses amounting up to 5 mg only and therefore PCA was discontinued on POD 1. Of the remaining 2 patients who had PCA discontinued on POD 2, one had pre-existing rheumatoid arthritis. Amongst the 16 patients who required rescue analgesics, 7 of them required opioids as detailed in Table 3. The remaining 9 used combinations of etoricoxib and gabapentin. Over the time course of the study, the trend in PCA prescription progressively decreased (Fig. 1). This was accompanied by an increase in the percentage of patients who only required non-opioid rescue analgesics (Fig. 2), as well as an increase in the percentage of patients who did not require any rescue analgesics (Fig. 3). The ICC was left in-situ for a mean duration of 3.69 ± 0.47 days. 8 patients (30.8%) were pain-free by POD 3 and had their ICC removed before the pump was depleted. There was 1 incident (3.8%) of peri-catheter leakage which was rectified by placing Dermabond® (Ethicon) around the catheter insertion site and securing the catheter to the skin with Tegaderm™ to prevent accidental dislodgement. None of the patients experienced adverse effects related to ropivacaine toxicity (perioral numbness, hallucinations, hypotension, arrhythmias).

Secondary outcomes are presented in Table 4. 2 patients (7.7%) had empyema, of which one had a persistent air leak and therefore had a chest drain in situ for 25 days. This particular patient was discharged after 31 days of hospitalisation. None of the patients had atelectasis or pneumonia. There were also no non-pulmonary complications like urinary retention, deep venous thrombosis, surgical site infection or mortality.

With the introduction of muscle-sparing and nerve-sparing incisions in thoracic surgery, pain due to rib or intercostal nerve trauma have been shown to be minimized [17‐19]. However, despite the usage of such techniques, significant acute postoperative pain has still been reported after UVATS [21, 22] and this is thought to be due to the irritation of the pleura or neurovascular bundles by chest tubes [23‐25]. Pain management in thoracic surgery should be multimodal, with an aim to avoid or minimize the use of opioids [26]. Opioids are associated with adverse effects like nausea, drowsiness and respiratory depression which may delay postoperative recovery [24]. In the era of an increasing emphasis on Enhanced Recovery After Surgery (ERAS®), there are clear guidelines supporting the utility of regional analgesia to avoid the use of opioids [16].

Till date, there has been no consensus on the gold standard for regional analgesia after video-assisted thoracoscopic surgery (VATS), much less UVATS [27]. Prospective, randomized studies comparing TEA and PVB in VATS cases have demonstrated conflicting results on pain scores and opioid consumption, but consistently showed that TEA was associated with a higher frequency of hypotension and urinary retention [2, 4, 5]. This has resulted in PVB becoming more appealing than TEA, but studies have revealed that a continuous infusion technique rather than a single-shot blockade resulted in the decreased need for opioids and more optimal pain control [28, 29]. Being a form of regional analgesia that can provide a continuous infusion, the ICC became the subject of interest in a few observational studies which supported its utility in reducing pain and opioid usage after VATS [13, 30‐32]. However, many of these studies have had mixed populations of single-port and multi-port VATS, thereby introducing heterogeneity in the available body of evidence. To the best of our knowledge, there was only one prior study focused on incorporating an ICC in UVATS exclusively, and the evidence of its utility in this domain remains sparse [33]. Aside from its relative novelty, our study is also distinctive in its inclusion of all consecutive patients who received the ICC since we first started using it in UVATS.

In our experience, the placement of an ICC provides adequate pain control after UVATS. In our earlier case series on muscle-sparing UVATS [34], we obtained mean pain scores of 0.2–0.4 on POD 1–5 before reaching 0.0 at POD 8. The inclusion of the ICC has improved our pain management, as evidenced by lower mean pain scores and earlier achievement of 0.0 on POD 5 in the present study. Our results also suggest that the ICC may assist with reduction in opioid usage. For most of our patients, a standardised regimen of an intercostal block and paracetamol, coupled with non-opioid rescue analgesics like etoricoxib and gabapentin, were adequate for pain management. These non-opioids were preferred due to their efficacy in controlling postoperative pain [35, 36]. In the small proportion of patients who required opioids, it is noteworthy that a weak-acting opioid like tramadol was sufficient. The frequency of PCA prescription also decreased over time when the acute pain team in our institution noted that minimal morphine boluses were required.

The ICC has multiple benefits in UVATS aside from pain control. Firstly, the catheter can be placed easily under direct vision, with confirmation of its placement by visualisation of an intercostal bulge after bolus administration of the analgesic. This is in contrast to TEA catheters which are inserted blindly and hence prone to mispositioning. The dosage of TEA also has to be titrated regularly which can be labour intensive. This is avoided with the ICC as the fixed pump volume and flow-limiting valve ensure an independent and constant flow rate. In addition, the ICC can be utilised when TEA is contraindicated, such as previous spine surgery or morbid obesity. Moreover, the ICC can deliver a continuous infusion beyond POD 1, thereby avoiding the short analgesic duration associated with single shot PVB. The ICC also enables early mobilisation since it is not associated with loss of motor function, as is the case with TEA. De Cosmo et al. [37] used an ICC-infusion regime similar to ours and reported a mean time to walking of 31.5 h, which is comparable to our findings. The portability of the ICC has also been demonstrated by Gebhardt et al. [38], who discharged 2 patients while the ICC was still in-situ. In our institution, we chose to err on the side of caution by removing the ICC in our patients before discharge. The median postoperative length of stay in our cohort was 3 days, which also compared favourably with the results by Ried et al. [39].

As with all equipment, technical failure is a concern but evidence on continuous anaesthetic infusion techniques like the ICC have shown the rate to be very low at 1% [40]. Our team’s specialised thoracic nurse reviewed all patients who received the ICC daily and would troubleshoot with the vendor if required. A potential drawback of the ICC is the risk of systemic toxicity. Jung and colleagues [32] reported that 3.3% of their patients who received the ICC complained of dizziness and drowsiness, with 2 patients requiring early discontinuation. It is our belief that with successful placement of the ICC confirmed intraoperatively, the risk of the analgesic entering systemic circulation is low. We further mitigated this risk by choosing to use an ICC with a fixed flow rate and clamp, to eliminate the possibility of increasing the flow rate accidentally and allow for quick cessation of the analgesic flow in an event of an emergency. A 16% rate of post-thoracotomy wound infection with the ICC has also been reported [39] but we did not observe the same findings, possibly because of the smaller incision in UVATS. Wheatley III and colleagues [41] claimed that the only contraindication to ICC is anaesthetic allergy and this is strongly supported by our team.

Our preliminary observational study was understandably not without its limitations. It was retrospective and based on a small sample size. We also acknowledge that the lack of a control group meant that our results should be interpreted with care. However, the use of a standardised ICC placement method, as well as a standardised analgesic regimen may have strengthened the validity of our findings. Pain score assessment was performed by uniformly trained nurses and analgesic usage was documented in a standardised manner in the electronic medical records, which may have helped to minimize biases in our study. Our findings have suggested that the ICC is simple and safe to utilize, and pain relief post-UVATS is also adequate. In the future, it is warranted to conduct larger-scale prospective randomized studies to further support the role of the ICC as regional analgesia in UVATS.

Our initial experience with the ICC demonstrated that it is feasible for incorporation into a multimodal analgesic strategy for UVATS. Its usage appears to be associated with minimal post-operative pain and reduced usage of opioids. It can therefore be considered as an adjunct to achieve early recovery after UVATS.