Ultrasound‐guided retrolaminar paravertebral block

Abstract

Paravertebral nerve blockade is considered an advanced technique due to the proximity of the neuraxis, pleura, abundant vasculature and other ‘danger zones’. The risk of pneumothorax associated with the traditional technique (‘walking’ the block needle off a transverse process into the paravertebral space), with or without ultrasound guidance, remains high 1, 2. This risk may be lessened by directing the block needle more medially, posterior to the vertebral lamina 3, 4, whilst avoiding unintentional neuraxial injection. We investigated whether the retrolaminar technique might be improved by ultrasound guidance. A 37-year-old woman was scheduled for bilateral prophylactic mastectomies and tissue expander reconstruction under general anesthesia with bilateral continuous ultrasound-guided retrolaminar blocks, after the risks, benefits and the novel aspects of these blocks had been discussed with the patient, and her consent given. With the patient in a sitting position and the skin sterilised, we passed a L38 linear ultrasound probe (SonoSite M-Turbo, SonoSite, Inc., Bothel, WA, USA) in a sagittal plane from medial to lateral at the mid-thoracic level, and identified the hyperechoic laminae, transverse processes, ribs and pleura (Fig. 6). The T3 laminae were identified approximately 4 cm subcutaneously, and an 18-G Tuohy-tip 10-cm block needle (SonoLong®, Pajunk Medizinteechnologie GmbH, Geisingen, Germany) was inserted in-plane, cephalad to caudad. After lamina contact and negative aspiration, 15 ml ropivacaine 0.5% was injected at low pressure (B-Smart™Pressure Manometer, Concert Medical, Norwell, MA, USA) with intermittent negative aspiration, creating a fluid-filled space between laminae and paraspinous muscles, without pain or paresthesia. The tips of two 20-G multi-orifice catheters (Perifix®, B. Braun Medical Inc., Bethlehem, PA, USA) were inserted into this space, with the catheters secured to the patient's skin. The patient received 150 μg fentanyl intra-operatively and 0.8 mg hydromorphine intravenously over 2 h in the recovery unit, where a further bolus of 15 ml ropivacaine 0.5% per side was given and mepivacaine 0.75% infusions commenced at 10 ml.h−1, bilaterally. On the first postoperative day, the patient required no opioids and had visual analogue pain scores of 1–4/10, with reduced sensation to sharp stimuli in the T3-T4 dermatomes on the right side and T3-T5 dermatomes on the left side. Paravertebral infusions were discontinued and the catheters removed on the second postoperative day; the patient received 20 mg oral oxycodone and 2 mg oral hydromorphone that evening, and was discharged home on day 3, with adequate pain control. We have performed more than 20 such blocks subsequently, with similar results and no complications, in patients undergoing uni/bilateral mastectomies, thoracotomy (3) or laparotomy (1), or with multiple rib fractures.