Weight-Based Volume of Injection Influences Cranial to Caudal Spread of Local Anesthetic Solution in Ultrasound-Guided Transversus Abdominis Plane Blocks in Canine Cadavers
ABSTRACT To determine if the volume of injected local anesthetic solution affects cranial to caudal spread when performing ultrasound-guided transversus abdominis plane (TAP) blocks in dogs.
Prospective experimental study.
Adult Beagle cadavers (n = 20)
Bilateral TAP blocks using ultrasound guidance was performed in 20 Beagle cadavers (mean ± SD weight, 9.3 ± 1.4 kg) using a 1:1 solution of methylene blue/bupivacaine injected at volumes of 0.25, 0.5, 0.75, and 1.0 mL/kg. Cadavers were dissected to determine injectate spread within the transversus abdominis fascial plane.
The transversus abdominis fascial plane was adequately identified by ultrasonography, injected, and dissected in 38 beagle hemi-abdominal walls; injectate was not identified in 2 hemi-abdominal walls. Dermatomal spread (number of ventral nerve roots saturated by injected solution) was volume dependent (P = .026, Kruskal Wallis): 2.9 ± 0.74 nerve roots for 0.25 mL/kg; 3.4 ± 1.1 for 0.5 mL/kg; 4.0 ± 0.67 for 0.75 mL/kg; and 4.2 ± 1.2 for 1 mL/kg.
In Beagle cadavers, the volume of injected local anesthetic solution significantly affects cranial to caudal spread within the TAP during ultrasound-guided TAP blocks. The volume of local anesthetic injected could potentially be used to augment the spread of analgesic coverage for a given surgical procedure in dogs.
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ABSTRACT: The landmark-guided transversus abdominis plane (TAP) block is an effective method of providing postoperative analgesia in patients undergoing lower abdominal surgery. We evaluated the analgesic efficacy of the ultrasound (US)-guided TAP block in patients undergoing Caesarean delivery. A randomized, double-blind, placebo-controlled trial was performed at a tertiary maternity hospital. Fifty women undergoing Caesarean delivery received bilateral US-guided TAP blocks with either ropivacaine 0.5% or saline. All participants received a spinal anaesthetic with bupivacaine and fentanyl, followed by postoperative acetaminophen, non-steroidal anti-inflammatory drugs, and patient-controlled i.v. morphine without long-acting intrathecal opioids. Each patient was assessed 24 h after delivery for morphine usage, average pain score, nausea, vomiting, pruritus, drowsiness, and satisfaction with pain relief. Forty-seven participants completed the trial, 23 in the active group and 24 in the placebo group. Total morphine use in 24 h was reduced in the active group (median 18.0 mg) compared with the placebo group (median 31.5 mg, P<0.05). The active group reported improved satisfaction with their pain relief measured by visual analogue scale compared with the placebo group (median 96 vs 77 mm, P=0.008). Fewer patients required antiemetics in the active group (P=0.03). There were no local complications attributable to the TAP block, but one participant had an anaphylactoid reaction after ropivacaine injection. The US-guided TAP block reduces morphine requirements after Caesarean delivery when used as a component of a multimodal analgesic regimen. Registered with the Australia New Zealand Clinical Trials Registry ACTRN12608000540314. URL: http://www.anzctr.org.au/trial_view.aspx?ID=83176.BJA British Journal of Anaesthesia 08/2009; 103(5):726-30. DOI:10.1093/bja/aep235 · 4.35 Impact Factor
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ABSTRACT: The transversus abdominis plane (TAP) block is a novel approach for blocking the abdominal wall neural afferents via the bilateral lumbar triangles of Petit. We evaluated its analgesic efficacy in patients during the first 24 postoperative hours after abdominal surgery, in a randomized, controlled, double-blind clinical trial. Thirty-two adults undergoing large bowel resection via a midline abdominal incision were randomized to receive standard care, including patient-controlled morphine analgesia and regular nonsteroidal antiinflammatory drugs and acetaminophen (n = 16), or to undergo TAP block (n = 16) in addition to standard care (n = 16). After induction of anesthesia, 20 mL of 0.375% levobupivacaine was deposited into the transversus abdominis neuro-fascial plane via the bilateral lumbar triangles of Petit. Each patient was assessed by a blinded investigator in the postanesthesia care unit and at 2, 4, 6, and 24 h postoperatively. The TAP block reduced visual analog scale pain scores (TAP versus control, mean +/- sd) on emergence (1 +/- 1.4 vs 6.6 +/- 2.8, P < 0.05), and at all postoperative time points, including at 24 h (1.7 +/- 1.7 vs 3.1 +/- 1.5, P < 0.05). Morphine requirements in the first 24 postoperative hours were also reduced (21.9 +/- 8.9 mg vs 80.4 +/- 19.2 mg, P < 0.05). There were no complications attributable to the TAP block. All TAP patients reported high levels of satisfaction with their postoperative analgesic regimen. The TAP block provided highly effective postoperative analgesia in the first 24 postoperative hours after major abdominal surgery.Anesthesia and analgesia 01/2007; 104(1):193-7. DOI:10.1213/01.ane.0000250223.49963.0f · 3.42 Impact Factor
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ABSTRACT: The transversus abdominis plane (TAP) block is an effective method of providing postoperative analgesia in patients undergoing midline abdominal wall incisions. We evaluated its analgesic efficacy over the first 48 postoperative hours after cesarean delivery performed through a Pfannensteil incision, in a randomized controlled, double-blind, clinical trial. Fifty women undergoing elective cesarean delivery were randomized to undergo TAP block with ropivacaine (n = 25) versus placebo (n = 25), in addition to standard postoperative analgesia comprising patient-controlled IV morphine analgesia and regular diclofenac and acetaminophen. All patients received a standard spinal anesthetic, and at the end of surgery, a bilateral TAP block was performed using 1.5 mg/kg ropivacaine (to a maximal dose of 150 mg) or saline on each side. Each patient was assessed postoperatively by a blinded investigator: in the postanesthesia care unit and at 2, 4, 6, 12, 24, 36, and 48 h postoperatively. The TAP block with ropivacaine compared with placebo reduced postoperative visual analog scale pain scores. Mean (+/- sd) total morphine requirements in the first 48 postoperative hours were also reduced (66 +/- 26 vs 18 +/- 14 mg, P < 0.001), as was the 12-h interval morphine consumption up to 36 h postoperatively. The incidence of sedation was reduced in patients undergoing TAP blockade. There were no complications attributable to the TAP block. The TAP block, as a component of a multimodal analgesic regimen, provided superior analgesia when compared with placebo block up to 48 postoperative hours after elective cesarean delivery.Anesthesia and analgesia 01/2008; 106(1):186-91, table of contents. DOI:10.1213/01.ane.0000290294.64090.f3 · 3.42 Impact Factor