An Audit of SubTenons block for Squint Surgery

An Audit of Sub-Tenons block for Squint Surgery in Children Dr Steve Gilbert Queen Margaret Hospital Dunfermline

Introduction • An audit of the post operative recovery from squint surgery, with and without sub-tenons block was carried out over four years. • Three surgeons operated on children, one of whom used sub-tenons laevobupivacaine at the end of the procedure (SS) and two who didn’t (AB & AB)

methods • Children received a standardised analgesic regime during anaesthesia • Fentanyl 1μg/kg at induction • Diclofenac 2 mg/kg PR at the end of surgery • Paracetamol 20 mg/kg as a loading dose, post op, followed by 15 mg/kg 4 hourly • Ibuprofen 10 mg/kg 6 h post op if reqd • Oramorph 0. 3 mg/kg if reqd • After repair of the conjunctiva one of the surgeons injected 1 ml 0. 5% laevobupivacaine to the sub tenons space (ST) while the others didn’t (N).

Data collection • Nurses scored the children’s pain and nausea at hourly intervals • 0 – none • 1 – mild • 2 – moderate • 3 – severe

Other data collected were; • Operation • Premed • quality of induction (happy-0, calm-1, scared-2, crying-3 or hysterical-4) • analgesic and antiemetic drugs given in theatre and in the ward post op • times of first drink, food and home readiness.

Results • Between December 2004 and November 2007 • 88 children between the ages of 1 and 17 • 60 had a sub tenons block (68%) and 28 didn’t (32%) • Average was 6. 6 (N) and 5. 2 (ST). • Mean quality of induction, graded 0 (happy) to 4 (hysterical) was 0. 68 (N) and 0. 72 (ST). • Average length of data collection 5. 5 h ST & 5. 2 h (N)

Operations • • Bilateral medial rectus in 28% (N) and 82% (ST) Single eye in 43% (N) and 0. 8% (ST) Re-operation in 7% (N) and 1. 5% (ST) Inferior oblique disinsertion in 11% (N) and 5% (ST)

Pain Scores • The maximum pain scores were 3 in 2%, 2 in 22% of the ST group and 1 in 40%, while 38% had no pain. • In the N group maximum pain scores were 3 in 11%, 2 in 41% and 1 in 33%. • Only 3 children had a score of 0 (11%). • Average pain scores were 0. 62 (N) and 0. 29 (ST).

Maximum Pain Scores

Paracetamol & other analgesics

PONV & anti-emetics

Time to oral intake & home readiness

Summary • The simple technique of sub-tenons block at the end of paediatric squint surgery leads to significantly less postoperative pain. • Only one child in the sub-tenons group complained of blurred vision. • There were no complications of the block. • There was more nausea & vomiting in the Sub-tenons group. ? Significance – follow up needed

Discussion • Previous studies have used topical 1 retrobulbar or subconjunctival LA • No difference in outcome • Pilot study showed significant effect at 2 hours with lignocaine 2%, but follow up RCT only found benefit at 1 h. 1, 2 • • 1. Yeşim A, Necmettin Ü, Handan C, Necile E, Postoperative analgesia in children using preemptive retrobulbar block and local anesthetic infiltration in strabismus surgery. Regional Anesthesia and Pain Medicine; 23, p 569574 , 1998 2. Carden, S M Adjunctive intra-operative local anaesthesia in paediatric strabismus surgery: a randomized controlled trial. Australian & New Zealand Journal of Ophthalmology. 26(4): 289 -97, 1998 Nov 3. Sheard R, Mehta J, Barry J et al, Subtenons Lidocaine Injection for Postoperative Pain Relief After Strabismus Surgery in Children: A Prospective Randomized Controlled Trial Journal of American Association for Pediatric Ophthalmology and Strabismus; 8(4): p 314 -17. 2004