The case series was registered at http://www.clinicaltrials.gov/
, ID: NCT01395043, and approved by the regional ethical committee. Fifteen patients undergoing elective lower major abdominal surgery with laparotomy and colon resection were prospectively included. As this was a case series, only registration of the patients accepting to participate was done. Enrolment started in September 2010 and finished in June 2011. Written informed consent was obtained before enrollment. Primary exclusion criteria were allergies to morphine or bupivacaine or inability to provide informed consent. Secondary exclusion criteria were reoperation within the first 48 hours or postoperative mechanical ventilation.
General anesthesia was induced with propofol 1-2
mg/kg or thiopenthal 3–5
mg/kg, remifentanil 1μ
g/kg and suxamethonium 1
mg/kg or cisatracurium 0.15
mg/kg at the discretion of the attending anesthesiologist. Following endotracheal intubation, anesthesia was maintained with sevoflurane at MAC 1 and remifentanil 0.3–1.0μ
g/kg/min. An intravenous dose of fentanyl 1-2μ
g/kg was given at the end of surgery. After induction of anesthesia, TAP catheters were placed bilaterally as described below. Surgery was performed by trained surgeons with all incisions performed in the lower abdominal wall below the umbilicus.
The TAP catheters were placed by the same experienced anesthetist under sterile conditions. A linear high-frequency ultrasound probe (HFL38, 13–6
MHz) covered with a sterile sheath (SITE-RITE* Probe Cover kit, Bard Access Systems Inc, Salt Lake City, USA) was used. An 18-gauge Touhy needle (Perican, B. Braun, Melsungen AG, Melsungen, Germany) was advanced in plane in a medial to lateral direction with ultrasound guidance using a SonoSite S-Nerve (SonoSite, Bothell, WA, USA) apparatus. The point of insertion was between the anterior and the mid-axillary line and between the lower costal margin and the iliac crest, based on the best visualization of TAP, expected surgical incision and preoperative stoma site marking. After reaching the TAP with the Touhy needle, hydrodissection was done with 10
mL of isotonic saline. An epidural catheter (Braun Perifix catheter, B. Braun, Melsungen AG, Melsungen, Germany) was introduced through the Touhy needle. With the Touhy needle bevel facing posteriorly, the catheter was advanced 15–20
cm inside the TAP in order to avoid displacement during patient movement and ambulation. After hydrodissection the advancement of the TAP catheter was unproblematic, although advancing the catheter less than 15
cm would probably have been sufficient to avoid displacement. The Touhy needle was removed and a filter (Perifix Filter 0.2μ
m, B. Braun, Melsungen AG, Melsungen, Germany) was connected to the catheter. Twenty mL of bupivacaine 2.5
mg/mL with epinephrine 5μ
g/mL was injected via each catheter with direct real-time ultrasound visualization to ensure correct placement of the TAP catheter. The TAP catheters were fixed using an epidural plaster (EPI-FIX, Unomedical Ltd, Stonehouse, Great Britain) and Mefix self-adhesive fixation (Mölnlycke, Health Care AB, Gothenburg, Sweden).
Three additional bolus doses of 20
mL bupivacaine 2.5
mg/mL were injected bilaterally via the TAP catheters 12, 24, and 36
hr after the first bolus dose (i.e., if duration of surgery was 2
hr, the second, third, and fourth bolus doses were given 10, 22, and 34
hr after end of surgery, resp.). In addition, all patients received a postoperative multimodal analgesic regimen consisting of paracetamol 1000
mg every 6
hr, ibuprofen 400
mg every 8
hr, and gabapentin 400
mg every 8
hr daily. Intravenous (IV) morphine 5–10
mg was used as rescue medication with the aim of ensuring a pain intensity of ≤3 at rest and ≤5 during coughing on a NRS, 0–10. Postoperative pain is generally considered to be acceptable if pain intensity is kept below these NRS levels.
Intensity of pain was assessed 0, 1, 2, 4, 8, 12, 18, 24, and 36
hr after surgery. Cumulative consumption of morphine within the first 48 postoperative hours was also recorded.