Subtenon block compared to intravenous fentanyl for perioperative analgesia in pediatric cataract surgery

General anesthesia with opioids provides good operative conditions for ocular surgery in children; however, postoperative pain management remains a significant problem. Regional anesthesia is commonly used as an adjunct to general anesthesia in children. We compared the efficacy and safety of subtenon block (SB) versus IV fentanyl for perioperative analgesia in pediatric cataract surgery. We hypothesized that perioperative analgesia using SB may reduce the requirement of postoperative rescue analgesia compared with fentanyl.

This was a prospective, randomized, controlled, double-blind trial. One hundred fourteen ASA I and II children (6 mo-6 yr) undergoing elective cataract surgery in one eye under general anesthesia were studied. Children were randomly allocated to one of the two groups, i.e., Group SB (n = 58) or Group F (n = 56) after securing the airway. Children in Group SB received SB with 0.06-0.08 mL/kg of 2% lidocaine and 0.5% bupivacaine (50:50) mixture and simultaneous 0.2 mL/kg normal saline IV, whereas children in Group F received 1 microg/kg (0.2 mL/kg of 5 microg/kg) of fentanyl IV and simultaneous subtenon injection with normal saline (0.06-0.08 mL/kg). Surgery started after 5 min of study drug administration. Postoperative assessment for pain, sedation, and nausea/vomiting was done at 0.5, 1, 2, 3, 4, and 24 h. The primary outcome was number of patients requiring rescue analgesia during the 24-h study period. Secondary outcomes assessed were pain and sedation scores, time to first rescue analgesia, incidence of occulocardiac reflex, and nausea/vomiting.

The number of patients requiring rescue analgesia during the 24 h was significantly less in Group SB (n = 17/58, 29.3%) compared with Group F (n = 39/56, 69.6%, P < 0.001). The postoperative pain scores were statistically lower in Group SB at all time intervals. The median (range) time to first analgesic requirement was significantly prolonged in Group SB (9 [corrected] [2-13] vs 4 [0.5-8.5] h in Group F) (P < 0.001). Sedation scores at (1/2) h were comparable, after which significantly more children were anxious or crying in Group F compared with Group SB in which more children were calm, sitting, or lying with eyes open and relaxed (P < 0.05). A significantly higher incidence of oculocardiac reflex was recorded in Group F versus Group SB (P = 0.019). No complication related to SB was noticed.

SB is a safe and superior alternative to IV fentanyl for perioperative analgesia in pediatric cataract surgery.