BackgroundDespite the popularity of continuous thoracic paravertebral block (TPVB), there is a paucity of information on catheter tip position and distribution of injectate through the catheter. We observed, in real time, the spread of dye, the catheter tip position and sensory block levels produced with three different (intercostal (IC), transverse process sagittal (TS) and paralaminar (PL)) approaches to ultrasound-guided TPVB in patients undergoing video-assisted thoracoscopic surgery.MethodsAfter the induction of general anesthesia, ultrasound-guided TPVB was conducted with a patient in the lateral decubitus position. During surgery, 10 mL of dye was injected through a catheter to observe the catheter tip and the dye distribution under thoracoscopy. Dermatomal sensory block levels were measured postoperatively.ResultsTen patients for each of three different approaches completed the study. There were a variety of dye spreading patterns. The median (range) number of segmental levels stained with dye was 1.5 (1–4), 3 (1–4) and 3 (1–5) with the IC, TS and PL approaches, respectively. We observed that a catheter tip was present at the same segmental paravertebral space as intended in 50%–90% of patients using these approaches. The median (range) number of dermatomes with sensory blockade at 6 hours after block was 2.5 (1–4), 3 (2–8) and 3 (1–8) with the IC, TS and PL approaches, respectively.ConclusionsAlthough a bolus injection through a catheter for ultrasound-guided TPVB produced multiple levels of spread and sensory blockade in more than half the patients, considerable differences existed in the spread regardless of approach.

Purpose Thoracic paravertebral block (TPVB) is a recommended regional analgesia during video-assisted thoracoscopic surgery (VATS). However, single-injection TPVB does not last long enough to provide sufficient acute postoperative pain relief. Continuous TPVB through a catheter is technically challenging and often unreliable. Intravenous dexamethasone extends the analgesic duration with some peripheral nerve blocks. However, data on the effect of intravenous dexamethasone on pain relief with TPVB are limited. This study aimed to assess the analgesic efficacy of intravenous dexamethasone in patients who received TPVB for VATS. Patients and Methods In this multicenter prospective randomized controlled trial, we recruited patients aged between 18 and 80 years with the American Society of Anesthesiologists of physical status class 1–3 and underwent elective VATS. Patients under general anesthesia randomly received 8 mg of intravenous dexamethasone (group D) or normal saline (group C). Ultrasound-guided TPVB (USG-TPVB) was performed at the T4–T5 and T6-T7 spaces. Multimodal analgesia was achieved via paracetamol, tramadol and intravenous morphine for both study groups. The primary outcome was time for the first analgesic requirement. Postoperative pain in terms of numeric rating score (NRS), total morphine consumption and postoperative nausea and vomiting (PONV) were assessed. Results After excluding one patient, 59 patients were analyzed. There were no intergroup differences in baseline characteristics. The time to first analgesic requirement was longer in group D (305 [240, 510] minutes) than in group C (270 [180, 300] minutes) ( P value = 0.02). The NRS at rest and on movement was lower in group D than in group C at 12 hours but did not differ at other time points. Postoperative morphine consumption was significantly lower in group D than in group C at 6,12,24 and 48 hours. Incidences of PONV were comparable between the groups. Conclusion Intravenous dexamethasone, used as an adjunct to a single-injection USG-TPVB prolonged analgesic duration, had an opioid-sparing effect and provided better postoperative pain relief after VATS.

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