Regional anesthesia, in the form of thoracic epidural anesthesia (TEA), thoracic paravertebral blocks (TPVB), and selective intercostal nerve blocks, have all successfully been used in conjunction with general anesthesia in thoracic surgical procedures.1,2 These methods all provide significant benefit to the patient by reducing opioid use both intraoperatively and postoperatively while maintaining pulmonary function.3 Specifically, the TPVB has been shown to provide more effective analgesia and maintain better pulmonary function than intravenous analgesia and to be safer than both intravenous analgesia and TEA in thoracic surgical cases.4,5
The ultrasound-guided serratus anterior plane (SAP) block was shown to be a safe and effective procedure to achieve numbness from T2 to T9 by Blanco et al6 in 2013. The same technique also provided effective analgesia in a patient with multiple rib fractures.7
In this case report, we describe 3 patients in whom the SAP block was used in conjunction with multilevel continuous TPVB to provide analgesia for chest tube site pain not adequately relieved by the TPVB. To our knowledge this is the first publication to address specifically the frequent chest tube site pain not adequately alleviated by TPVB or TEA alone.
All blocks were percutaneously placed in the operating room before induction of anesthesia under real-time ultrasound guidance utilizing the SonoSite Edge monitor (FUJIFILM SonoSite, Inc, Bothell, WA) and a 13–6 MHz linear transducer. Eighteen-gauge Pajunk Tuohy tip echogenic block needles and Braun 20-gauge 4-inch closed tip marked polyamide epidural catheters were used in all cases. Sterile techniques were adhered to throughout, including utilization of ultrasound transducer sleeve covers.
Serratus Anterior Plane Block
Using an in-plane approach, the performance of the SAP block was similar to that described by Blanco et al6 with the final position of the transducer near the midaxillary line and the block needle tracking from an anteromedial to posterolateral direction. The SAP block placement target was the interfascial plane on the superficial surface of the serratus anterior muscle at approximately T5 (Figure 1). After bolus injection of local anesthesia (LA) and ultrasound confirmation of proper hydrodissection of the tissue plane, the block catheter was threaded 2 to 3 cm beyond the needle tip. An antimicrobial disk was placed over the catheter skin entry site, and the catheter was secured with application of Mastisol liquid adhesive (Eloquest Healthcare) under Tegaderm clear film dressing (3M), routing the distal catheter toward the shoulder.
Thoracic Paravertebral Block
The continuous TPVB was performed with the patient in the sitting position with both patient arms extended and supported by a pillow-cushioned Mayo stand. An ultrasound-guided in-plane parasagittal approach with block needle tracking from a caudal to cephalad direction was used. After passing through the superior costotransverse ligament, proper needle placement was further confirmed by anterior deflection of the parietal pleura on injection of LA. The block catheter was threaded 2 cm beyond the needle tip, an antimicrobial disk was placed, and the catheter was secured in a similar fashion as that of the SAP block.
Midazolam IV and fentanyl IV were used to provide sedation during performance of the blocks. Anesthesia was induced with additional midazolam IV, additional fentanyl IV, and propofol IV mixed with 25 mg preservative-free lidocaine. Anesthesia was maintained with desflurane at 1 minimum alveolar concentration and hydromorphone 0.5 mg IV. Rocuronium provided muscle relaxation, which was reversed using neostigmine and glycopyrrolate. The procedure durations ranged between 3 and 7 hours.
One-lung ventilation was accomplished using left-sided double-lumen endotracheal tubes. All continuous block infusions used 0.2% preservative-free ropivacaine and were started in the postanesthesia care unit. All initial and intermittent bolus block injections contained 0.25% preservative-free bupivacaine. All surgeries were performed by the same attending and assistant surgeons. The chest tube insertion sites were either the 7th or 8th intercostal space on the midaxillary line. All chest tubes placed were size 28 French. Two chest tubes were utilized for each of cases 1 and 3, while case 2 received only 1 (Figures 2–4). Adjuvant multimodal postoperative pain management, when necessary, included one or more of the following: hydromorphone IV, hydrocodone/acetaminophen per os, oxycodone/acetaminophen per os, gabapentin per os, and acetaminophen IV. The first author performed all the TPVB and SAP blocks, administered the general anesthesia, and provided the postoperative follow-up and management.
Our main objectives with the SAP block were to alleviate the persistent problematic chest tube site pain that, for many years, the first author has observed to occur even in the presence of properly functioning TPVB or TEA and to reduce total opioid use. Better pain control leads to improved pulmonary function, improved mobility, and decreased opioid use, which in turn allows for more rapid return of bowel and urinary bladder function and fewer negative cognitive effects.
Statement of Consent
The 3 patients described in this case report all received copies of the manuscript. They and/or their family have provided both written and verbal permission for the presentation and publication of their cases.
A 61-year-old 75.8 kg man presented for surgery with a diagnosis of secondary malignant neoplasm from a primary right lung malignancy. The surgical procedure performed was a right thoracotomy using one-lung ventilation with right lower lobe sublobar resection. Right unilateral continuous TPVB at levels T3, T5, and T7, and right unilateral continuous SAP block were placed. Initial bolus injections totaled 90 mL between the 4 block sites. Continuous infusions were set at 3 to 4 mL/h via each catheter. On postoperative days (POD) 3 and 4, the patient received additional bolus injections in all 4 catheters. The chest tubes and block catheters remained in place until POD 4. He was discharged on POD 5. The patient reported excellent pain control throughout his hospital stay. In particular, he reported no chest tube–related pain, only mild discomfort at the chest tube site with physical activities, which quickly resolved with bolus injections.
A 76-year-old 96.2 kg man underwent a right thoracotomy using one-lung ventilation, right lower lobe superior segmentectomy, and additional second right lower lobe sublobar wedge resection. Right continuous TPVB at levels T3 and T5, and right continuous SAP block were placed. Initial bolus injections totaled 88 mL. Continuous infusions were set at 2 to 3 mL/h for each block catheter. On the evening of the operative day, the patient received additional bolus injections of 12, 10, and 14 mL via the right SAP block, right upper TPVB, and right lower TPVB catheters, respectively. On POD 2 and 3, the patient received additional bolus injections totaling 24 and 21 mL, respectively, via the TPVB catheters. The chest tube was removed and the continuous infusions via the 3 catheters were stopped on POD 3. Subsequently, the block catheters were removed and the patient was discharged on POD 4. During the entire postoperative period, the patient only experienced minor discomfort when coughing aggressively, but was otherwise pain free. He did experience some right upper extremity weakness on POD 1, which resolved by POD 2.
A 63-year-old 87.0 kg man underwent a right thoracotomy with one-lung ventilation for an Ivor-Lewis esophagectomy and placement of feeding jejunostomy tube. Right continuous TPVB at levels T3, T5, and T8, left continuous TPVB at T8, and a right continuous SAP block were placed. Initial injections totaled 52 mL via the 4 TPVB and 12 mL via the SAP block. Continuous infusions were set at 2 mL/h via each block catheter. The patient received daily bolus injections on POD 1 through POD 9. The bolus injections were stopped after POD 9 due to LA backflow and collection under the catheter dressing. The right T5 TPVB catheter was dislodged on POD 6. The left T8 TPVB catheter was dislodged on POD 7. The right T8 TPVB was dislodged on POD 8. Total daily bolus injection volumes ranged from 32 to 41 mL depending on the number of available catheters. The remaining right T3 TPVB and SAP block catheters were removed on POD 10. The chest tube was removed on POD 14, and the patient was discharged on POD 15. On POD 1, the patient reported no incisional pain and was not aware that he had 2 chest tubes in place. He did report the continued presence of his chronic baseline preexisting right shoulder pain. He denied incisional and chest tube–related pain while all the catheters were functioning. On POD 8, after dislodgment of several catheters, he reported some incisional discomfort but continued to deny chest tube–related pain. However, overall analgesia remained excellent until the block catheters were removed on POD 10.
A recurring complaint after thoracic surgery is chest tube–related pain that is not blocked sufficiently by TPVB, TEA, or selective intercostal nerve blocks. This is possibly due, in part, to unblocked nociceptive signals from the long thoracic nerve (LTN), the phrenic nerve, the thoracodorsal nerve, the vagus nerve, and incompletely blocked intercostal nerves.4,8 The LTN is derived from small branches leaving the ventral rami of C5, C6, and C7 nerve roots while the thoracodorsal nerve emanates from the ventral rami of C6, C7, and C8 nerve roots. The distal course of the LTN runs along the midaxillary line on the superficial surface of the serratus anterior muscle. Because of its origin and trajectory, it is not blocked by TPVB, TEA, or by any selective intercostal nerve blocks. Varghese et al9 used SAP dye injections in frozen cadavers to demonstrate that a properly performed SAP block spreads sufficiently to cover the LTN as well as the lateral cutaneous branches of T2 to T5 intercostal nerves.
Although the LTN has classically been considered a motor nerve, recent thinking has challenged the premise that only sensory nerve blockade is necessary for analgesia.8 Mayes et al8 injected methylene blue and latex into the tissue plane on the deep surface of the serratus anterior muscle in 6 soft-fix embalmed cadavers. They found widespread methylene blue dye and latex in the tissue plane deep to the serratus anterior muscle but no latex spread to the intercostal nerves. They concluded that the analgesic effect of SAP blocks is mediated through blockade of the lateral cutaneous branches of the intercostal nerves rather than direct blockade of the intercostal nerves. Because only the lateral cutaneous branches are blocked, structures innervated by other parts of the intercostal nerves and structures innervated by the dorsal rami of the spinal nerves are not covered. Therefore, SAP blocks do not seem to be equivalent to TPVB, whether used for rib fracture analgesia or for postthoracotomy analgesia, as has been suggested.6,8 However, SAP blocks can complement TPVB, TEA, and selective intercostal nerve blocks.
Even though our cases involve effort-intensive multiple catheter TPVB, less labor-demanding single-catheter techniques can equally benefit from concurrent use of SAP blocks. The SAP block was used in our cases as an adjuvant to alleviate the persistent chest tube–related pain from residual unblocked nociceptive signals. All 3 patients presented in this report did extremely well during their hospital stays, specifically reporting minimal to no chest tube–related pain during daily postoperative visits and examinations. Of note, the patient in case 3 was unaware of the presence of his 2 chest tubes. This success speaks to the effectiveness of the multimodal analgesia approach, including the continuous block infusions and intermittent bolus injections. All 3 patients were administered some opioids postoperatively. However, no patient reported the common issues seen with heavier opioid use, such as ileus, urinary bladder dysfunction, respiratory depression, nausea/vomiting, and cognitive impairment.
Although quantitative pain-rating scores might have added some additional objectivity to our findings, we did not report any quantitative pain-rating scores because of the disadvantage inherent in all single-dimensional pain-rating scales, such as the numerical rating scale universally used at our institution for nursing postoperative pain assessment. The numerical rating scale attempts to assign a single value to a complex, multidimensional experience.10 In our cases, where pain sources can come from multiple different locations, etiologies, or preexisting conditions, the nursing-documented pain score numbers do not necessarily reflect on one particular parameter or differentiate contributions from different sources. Chest tube–related pain was never mentioned in any of the nursing entries for all 3 cases. The single most reliable indicator of the presence and intensity of pain is from patient’s self-report, which we included.10
Also of note, no infections occurred at the catheter sites despite leaving the catheters in place for multiple days, which for the patient in case 3 was until POD 10. This can be credited to sterile technique used when placing the catheters, the careful handling of infusions and bolus injections, and the excellent nursing care in the intensive care unit and on the floor.
Finally, dosing of LA intraoperatively, in continuous infusions, and in subsequent bolus injections appears to have been sufficient to provide good analgesia without significant serratus anterior muscle dysfunction or LA toxicity. The patient in case 2 did report some shoulder weakness on the ipsilateral side of his blocks on POD 1, but this had resolved when reassessed on POD 2. The most likely etiology was transient cephalad spread of LA used in the TPVB.
In our patient population, properly performed and otherwise effective TPVB and TEA have previously failed to adequately address the significant chest tube site pain after invasive thoracic procedures. Our experience with these 3 cases seems to indicate that the SAP block has the potential to be a useful adjunct to a multimodal approach for alleviating the persistent chest tube–related pain not fully mitigated by TPVB, TEA, or intercostal nerve blocks following thoracic surgery. We hope this small case study inspires further investigation and analysis of this novel regional anesthetic technique.
Name: George M. Chu, MD.
Contributions: This author helped write and edit the manuscript, and was the originator of the innovative technique application, and 100% direct patient care.
Name: G. Craig Jarvis, DO Candidate.
Contributions: This author helped collect the data, and write and edit the manuscript.
This manuscript was handled by: Raymond C. Roy, MD.
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