Ultrasound-guided rectus sheath block or wound infiltration in children: a randomized blinded study of analgesia and bupivacaine absorption.
BACKGROUND
Rectus sheath block can provide analgesia following umbilical hernia repair. However, conflicting reports on its analgesic effectiveness exist. No study has investigated plasma local anesthetic concentration following ultrasound-guided rectus sheath block (USGRSB) in children.


OBJECTIVE
Compare the effectiveness and bupivacaine absorption following USGRSB or wound infiltration (WI) for umbilical hernia repair in children.


METHODS
A randomized blinded study comparing WI with USGRSB in 40 children undergoing umbilical hernia repair was performed. Group WI (n = 20) received wound infiltration 1 mg·kg(-1) 0.25% bupivacaine. Group RS (n = 20) received USGRSB 0.5 mg·kg(-1) 0.25% bupivacaine per side in the posterior rectus sheath compartment. Pain scores and rescue analgesia were recorded. Blood samples were drawn at 0, 10, 20, 30, 45, and 60 min.


RESULTS
Patients in the WI group had a twofold increased risk of requiring morphine (hazard ratio 2.06, 95% CI 1.01, 4.20, P = 0.05). When required, median time to first morphine dose was longer in the USGRSB group (65.5 min vs. 47.5 min, P = 0.049). Peak plasma bupivacaine concentration was higher following USGRSB than WI (median: 631.9 ng·ml(-1) IQR: 553.9-784.1 vs. 389.7 ng·ml(-1) IQR: 250.5-502.7, P = 0.002). Tmax was longer in the USGRSB group (median 45 min IQR: 30-60 vs. 20 min IQR: 20-45, P = 0.006).


CONCLUSIONS
USGRSB provides more effective analgesia than WI for umbilical hernia repair. USGRSB with 1 mg·kg(-1) 0.25% bupivacaine is associated with safe plasma bupivacaine concentration that peaks higher and later than WI. Caution against using larger volumes of higher concentration local anesthetic for USGRSB is advised.
Department of Anesthesiology and Pain Medicine, University of Washington School of Medicine and Seattle Children's Hospital, Seattle, WA, USA.
Sean H
SH
Flack
Lizabeth D
LD
Martin
Benjamin J
BJ
Walker
Adrian T
AT
Bosenberg
Laurilyn D
LD
Helmers
Adam B
AB
Goldin
Charles M
CM
Haberkern
D000293:Adolescent; D000698:Analgesia / Q000379:methods*; D000779:Anesthetics, Local / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D002045:Bupivacaine / Q000008:administration & dosage / Q000493:pharmacokinetics* / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D005260:Female; D006554:Hernia, Umbilical / Q000601:surgery*; D006801:Humans; D007223:Infant; D008297:Male; D009407:Nerve Block / Q000379:methods*; D017568:Rectus Abdominis / Q000000981:diagnostic imaging / Q000187:drug effects; D016037:Single-Blind Method; D016896:Treatment Outcome; D018084:Ultrasonography, Interventional
D000779:Anesthetics, Local; D002045:Bupivacaine
age, outpatient; ambulatory, local anesthetics; drugs; drugs, regional; pain, child; pharmacokinetics; ultrasound, regional