Influence of Pre- and Intraoperative Local Anaesthetic in Strabismus Surgery under General Anaesthesia in Adults.

BACKGROUND: As studies have shown a reduction in the occurrence of the oculocardiac reflex with the addition of local anaesthesia, we changed our care regime accordingly a few years ago. To promote and establish better patient care, we retrospectively analysed the files of our patients who underwent strabismus surgery from 2013 to 2021 in order to compare strabismus surgery under general anaesthesia with and without local anaesthetics in a routine clinical setting. PATIENTS AND METHODS: Data from 238 adult patients who had undergone strabismus surgery could be extracted from the files: G1: n = 102, only general anaesthesia; G2: n = 136, preoperative application of tetracaine eye drops and intraoperative subtenon lidocaine/levobupivacaine in addition to general anaesthesia. We compared the two groups in regard to the frequency of oculocardiac reflex, the amount of atropine needed to treat, as well as the amount of antiemetic and analgesic medication given, and time spent in the recovery room. RESULTS: Mean age of G1 was 50 years and 52 years in G2. There was no significant difference between the kind of surgeries (recessions/resections), the number of patients who had undergone a reoperation, or the duration of the operations. Adding local anaesthetics resulted in significantly less occurrence of oculocardiac reflex (p = 0.009), a reduction in the need for atropine, analgesic, or antiemetic medication, as well as reduced time in the recovery room. CONCLUSION: As this increases patient safety and comfort and is cost-effective (less time in the recovery room), we recommend adding perioperative local anaesthesia to strabismus surgery performed under general anaesthesia.

Penehyclidine mitigates postoperative nausea and vomiting and intraoperative oculocardiac reflex in patients undergoing strabismus surgery: a prospective, randomized, double-blind comparison.

BACKGROUND: Postoperative nausea and vomiting (PONV) is one of the most frequent complications following strabismus surgery. Penehyclidine, an anticholinergic agent, is widely used as premedication. This study investigated the effect of preoperative penehyclidine on PONV in patients undergoing strabismus surgery. METHODS: In this prospective, randomized, double-blind study, patients scheduled for strabismus surgery under general anesthesia were randomly assigned to either penehyclidine (n = 114) or normal saline (n = 104) group. Penehyclidine was administrated immediately after anesthesia induction, and normal saline was substituted as control. PONV was investigated from 0 to 48 h after surgery. Intraoperative oculocardiac reflex (OCR) was also recorded. RESULTS: Compared with normal saline, penehyclidine significantly reduced PONV incidence (30.7% vs. 54.8%, P < 0.01) and mitigated PONV severity as indicated by severity scoring (P < 0.01). Compared with normal saline, penehyclidine also significantly reduced OCR incidence (57.9% vs. 77.9%, P < 0.01) and mitigated OCR severity, as indicated by the requirement for atropine rescue (77.3% vs. 90.1%, P < 0.05) and the maximum decrease of heart rate during OCR (23.1 ± 9.4 bpm vs. 27.3 ± 12.4 bpm, P < 0.05). The recovery course did not differ between groups. CONCLUSIONS: Penehyclidine administrated after anesthesia induction significantly reduced the incidence of PONV and alleviated intraoperative OCR in patients undergoing strabismus surgery. TRIAL REGISTRATION: ClinicalTrials.gov ( NCT04054479 ). Retrospectively registered August 13, 2019.

Effect of dexmedetomidine on prevention of postoperative nausea and vomiting in pediatric strabismus surgery: a randomized controlled study.

BACKGROUND: Postoperative nausea and vomiting (PONV) are common side-effects following strabismus surgery. The present study aimed to compare the effects of different doses of dexmedetomidine (DEX) on PONV incidence in pediatric patients undergoing strabismus surgery. METHODS: In this prospective randomized double-blinded study, 126 pediatric patients undergoing strabismus surgery were randomized into one of three groups: Placebo group, normal saline; DEX1 group, 0.3 µg/kg dexmedetomidine, and DEX2 group, 0.5 µg/kg dexmedetomidine. Oculocardiac reflex (OCR) events were recorded during surgery. PONV or postoperative vomiting (POV) was recorded for 24 h in the ward. Pediatric anesthesia emergence delirium (PAED) scale and emergence agitation (EA) scale were recorded in the recovery room. RESULTS: Intraoperative OCR was significantly reduced in DEX2 group (42%) as compared to that of Placebo group (68%) (p = 0.0146). During the first 24 h post-op, the overall incidence of PONV was significantly lower in DEX2 group (10%) than that of Placebo group (32%) (p = 0.0142). There was no significant difference in POV among the three groups. PAED or EA scores among the three groups were similar during recovery time. CONCLUSION: Dexmedetomidine (0.5 µg/kg) reduced OCR and PONV without lengthening extubation time or recovery time in pediatric patients undergoing strabismus surgery. TRIAL REGISTRATION: The trial was prospectively registered before patient enrollment at Chinese Clinical Trial Registry (Clinical Trial Number: ChiCTR1800020176, Date: 12/19/2018).

The oculocardiac reflex and depth of anesthesia measured by brain wave.

BACKGROUND: The oculocardiac reflex (OCR), bradycardia that occurs during strabismus surgery is a type of trigemino-cardiac reflex (TCR) is blocked by anticholinergics and enhanced by opioids and dexmedetomidine. Two recent studies suggest that deeper inhalational anesthesia monitored by BIS protects against OCR; we wondered if our data correlated similarly. METHODS: In an ongoing, prospective study of OCR/TCR elicited by 10-s, 200 g square-wave traction on extraocular muscles (EOM) from 2009 to 2013, anesthetic depth was estimated in cohorts using either BIS or Narcotrend monitors. The depth of anesthesia was deliberately varied between first and second EOM tested. RESULTS: From 1992 through 2013, 2833 cases of OCR during strabismus surgery were monitored. Excluding re-operations and cases with anticholinergic, OCR from first EOM traction averaged - 20.2 ± 21.8% (S.D.) with a range from - 95 to + 25% in patients aged 0.2 to 90 (median 6.5) years. We did not find correlation between %OCR and brain wave for 97 patients with BIS monitoring and 91 with Narcotrend. With intra-patient controls between first and second muscle, the difference in brain wave did not correlate with difference in %OCR for BIS (r = 0.0002, 95% C. I -0.0002, 0.002, p = 0.30) or for Narcotrend (r = - 0.001, 95% C. I -0.004, 0.001, p = 0.32). Secondary multi-variable analysis demonstrated significant association on %OCR particularly with BIS monitor, opioid, propofol and nitrous oxide concentration in the second EOM tensioned. Sevoflurane concentration correlated better with BIS monitor in second and third EOM tension. %OCR correlated with younger age (p < 0.01). OCR with rapid onset was more profound than those with gradual onset (difference in means 18, 95% C. I 10, 26%). CONCLUSIONS: We were unable to confirm a direct correlation between brain wave monitor and OCR when using multifactorial anesthetic agents. The discrepency with other studies probably reflects direct impact of inhalational agent concentration and less deliberate quantification of EOM tension. We found no level of BIS or Entropy EEG monitoring that uniformly prevents OCR. TRIAL REGISTRY: NCT03663413. DATA: http://www.abcd-vision.org/OCR/OCR%20Brainwave%20de-identified.pdf .

A randomised comparison of lidocaine 2% gel and proparacaine 0.5% eye drops in paediatric squint surgery.

We conducted a randomised trial comparing lidocaine 2% gel with proparacaine 0.5% eye drops in children having elective squint surgery. One hundred and forty children aged between 3 and 14 years were recruited. The requirement for intra-operative fentanyl and postoperative ibuprofen was significantly less in the lidocaine group compared with the proparacaine group (1 (1.7%) vs 12 (18.5%), p=0.002 and 16 (27.6%) 38 (58.5%), p=0.001, respectively). The incidence of postoperative nausea and vomiting was significantly less in the lidocaine group compared with the proparacaine group (6 (10.3%) vs 16 (24.6%), p=0.04). There were no differences between the groups in terms of incidence and severity of the oculocardiac reflex. We conclude that, compared with proparacaine 0.5% eye drops, a single application of lidocaine 2% gel improves peri-operative analgesia and reduces the incidence of postoperative nausea and vomiting in elective paediatric squint surgery.

Efficacy of subtenon block in infants - a comparison with intravenous fentanyl for perioperative analgesia in infantile cataract surgery.

BACKGROUND: General anesthesia with opioids provides good perioperative analgesia in infantile ocular surgeries but is associated with the risk of respiratory depression and postoperative emesis. This study aimed to assess the effectiveness of subtenon block for providing perioperative analgesia in infants undergoing cataract surgeries. METHODS: In this prospective, randomized, controlled, double-blinded trial, 63 infants of ASA grade I and II (1-12 months) were recruited to receive either subtenon block (Group SB) or 1 µg·kg(-1) i.v. fentanyl (Group F) after induction of anesthesia. Primary outcome was the number of infants requiring rescue analgesia during 4-h study period before discharge of the infants. Secondary outcomes assessed were CRIES pain score, incidence of oculocardiac reflex, surgical difficulty, and incidence of postoperative emesis. RESULTS: The number of infants requiring rescue analgesia during 4-h study period was significantly less in Group SB (n = 6/32, 18.8%) compared to Group F (n = 14/31, 45.2%, P = 0.032). CRIES scores were significantly lower at and after 40 min compared to immediate postoperative period in Group F while these were comparable at all time intervals in Group SB. CRIES scores were significantly lower in Group SB compared to Group F at all time intervals except at 1 h. The incidence of oculocardiac reflex and the postoperative emesis were comparable in both the groups. CONCLUSION: Subtenon block is an effective superior technique for postoperative analgesia compared to intravenous fentanyl in infants undergoing cataract surgery.

The oculocardiac reflex may mimic signs of intracranial hypertension in patients with combined cerebral and ocular trauma.

BACKGROUND: In the setting of head trauma, progressive bradycardia may raise suspicion for intracranial hypertension, especially when accompanied by pupillary abnormalities or systemic hypertension. METHODS: We describe the case of a patient with concomitant cerebral and ocular trauma who presented with a fixed and dilated pupil and progressive bradycardia due to an oculocardiac reflex. RESULTS: The oculocardiac reflex is an unusual cause of bradycardia due to stimulation of the ophthalmic division of the trigeminal nerve and has been described in a variety of clinical settings. CONCLUSIONS: Clinicians should be aware that the oculocardiac reflex might mimic signs of intracranial hypertension in patients with combined facial and cerebral trauma.

[Pitfalls of anesthesiologic management in paediatric strabismus surgery]. / Tipps und Tricks---Anästhesie bei Strabismusoperationen im Kindesalter.

Strabismus surgery is one of the most common paediatric operation procedures. As associated with congenital syndrome, congenital heart disease and neuromuscular disorder, the anesthesiologic management has to be planned carefully. Considering high incidences of oculocardiac reflex (OCR) and postoperative nausea and vomiting (PONV) anesthesia can be performed to decrease both. Induction of anesthesia with ketamine or midzolam reduces risk of oculocardiac reflex, whereas propofol or remifentanil lead to higher incidences of OCR. A combination anti-emetic therapy from different drug classes is recommend to patients at high risk for nausea and vomiting like patients undergoing strabismus surgery. A combination therapy of ondansetron and dexamethasone lead to a risk reduction of PONV to at least 10 %. Further, the incidence of OCR and PONV is significantly reduced in children receiving peribulbar block on top of general anaesthesia.

Perioperative dexmedetomidine reduces emergence agitation without increasing the oculocardiac reflex in children: A systematic review and meta-analysis.

BACKGROUND: Intravenous dexmedetomidine (DEX) has been used to prevent emergence agitation (EA) in children. The aim of this meta-analysis was to evaluate whether DEX decreases EA incidence without augmenting oculocardiac reflex (OCR) in pediatric patients undergoing strabismus surgery. METHODS: We searched PubMed, EMBASE, Chinese National Knowledge Infrastructure (CNKI), Wan Fang, and the Cochrane Library to collect the randomized controlled trials (RCTs) investigating the effects of intraoperative DEX in children undergoing strabismus surgery from inception to October 2019. Postoperative Pediatric Agitation and Emergence Delirium (PAED) score, postoperative EA, extubation or laryngeal mask airway (LMA) removal time, postanesthetic care unit (PACU) stay time, OCR, and postoperative vomiting (POV) were evaluated. RESULTS: 11 RCTs including 801 patients were included in this study. Compared with control group, intravenous DEX significantly reduced postoperative PAED score (WMD, 3.05; 95% CI: -3.82 to -2.27, P = .017) and incidences of postoperative EA 69% (RR, 0.31; 95% CI: 0.17 to 0.55, P < .00) and POV (RR, 0.28; 95% CI: 0.13 to 0.61, P = .001). Furthermore, the use of DEX significantly delayed extubation or LMA removal time (WMD, 2.11; 95% CI: 0.25 to 3.97, P < .001). No significant difference was found in the incidence of ORC and PACU stay time. CONCLUSION: Intravenous DEX reduced the incidences of EA without increasing OCR in pediatric patients undergoing strabismus surgery. Meanwhile, DEX infusion decreased the incidence of POV in children.

The effect on outcome of peribulbar anaesthesia in conjunction with general anesthesia for vitreoretinal surgery.

The purpose of this study was to evaluate peri-operative outcome after vitreoretinal surgery when peribulbar anaesthesia is combined with general anaesthesia. Sixty adult patients undergoing elective primary retinal detachment surgery with scleral buckling or an encircling procedure received either peribulbar anaesthesia in conjunction with general anaesthesia or general anaesthesia alone. For peribulbar anaesthesia a single percutaneous injection of 5-7 ml of local anaesthetic solution (0.75% ropivacaine with hyaluronidase 15 iu.ml(-1)) was used. The incidence of intra-operative oculocardiac reflex and surgical bleeding interfering with the surgical field, postoperative pain and analgesia requirements, and postoperative nausea and vomiting were recorded. In the block group there was a lower incidence of oculocardiac reflex and surgical bleeding intra-operatively. Patients in the block group also had better postoperative analgesia and a lower incidence of postoperative nausea and vomiting compared with the group without a block. The use of peribulbar anaesthesia in conjunction with general anesthesia was superior to general anaesthesia alone for vitreoretinal surgery with scleral buckling.

Orbital trauma, bradycardia, and vomiting: trapdoor fracture and the oculocardiac reflex: a case report.

The presentation of vomiting and bradycardia after closed head trauma should invariably prompt concern for significant intracranial injury, yet other less common causes for the clinical picture do exist. This case reports one such scenario in which fracture to the patient's inferior orbital wall resulted in the rare though potentially life-threatening oculocardiac reflex, a vagally mediated phenomenon with possible respiratory, cardiovascular, and gastric motility effects.

Dexmedetomidine use in pediatric strabismus surgery: A systematic review and meta-analysis.

BACKGROUND: Common complications of pediatric strabismus surgery, including emergence agitation (EA), postoperative nausea and vomiting (PONV), and postoperative pain, may be prevented using dexmedetomidine, which is an anxiolytic and analgesic. This systematic review and meta-analysis assessed the effects of dexmedetomidine in patients who had undergone pediatric strabismus surgery. METHOD: Five databases were searched for randomized controlled trials published from database inception to April 2020 that compared dexmedetomidine use with placebo or active comparator use and evaluated EA, PONV, or postoperative pain incidence (main outcomes) in patients who had undergone pediatric strabismus surgery. Oculocardiac reflex (OCR) incidence and postanesthesia care unit (PACU) stay duration were considered as safety outcomes. All meta-analyses were performed using a random-effects model. RESULTS: In the nine studies meeting our inclusion criteria, compared with placebo use, dexmedetomidine use reduced EA incidence [risk ratio (RR): 0.39; 95% confidence interval (CI): 0.25-0.62, I2 = 66%], severe EA incidence (RR: 0.27, 95% CI: 0.17-0.43, I2 = 0%), PONV incidence (RR: 0.33, 95% CI: 0.21-0.54, I2 = 0%), analgesia requirement (RR: 0.38, 95% CI: 0.25-0.57, I2 = 0%), and pain scores (standardized mean difference: -1.02, 95% CI: -1.44 to -0.61, I2 = 75%). Dexmedetomidine also led to lower EA incidence in the sevoflurane group than in the desflurane group (RR: 0.26 for sevoflurane vs. 0.45 for desflurane). Continuous dexmedetomidine infusion (RR: 0.19) led to better EA incidence reduction than did bolus dexmedetomidine infusion at the end of surgery (RR: 0.26) or during the peri-induction period (RR: 0.36). Compared with placebo use, dexmedetomidine use reduced OCR incidence (RR: 0.63; I2 = 40%). No significant between-group differences were noted for PACU stay duration. CONCLUSION: In patients who have undergone pediatric strabismus surgery, dexmedetomidine use may alleviate EA, PONV, and postoperative pain and reduce OCR incidence. Moreover, dexmedetomidine use does not affect the PACU stay duration.

Comparison of sub-Tenon's block with i.v. fentanyl for paediatric vitreoretinal surgery.

BACKGROUND: Vitreoretinal (VR) surgery is associated with moderate to severe pain and significant postoperative nausea and vomiting (PONV). The study aimed to assess the effectiveness of sub-Tenon's block for providing perioperative analgesia in children undergoing VR surgery. METHODS: In a randomized, observer-blinded trial, after obtaining institutional ethical committee approval and parental consent, 200 ASA grade I-II children aged 5-16 yr were allocated to receive either a sub-Tenon's block (Group SB) or 2 microg kg(-1) i.v. fentanyl (Group F) after induction of anaesthesia and topical anaesthesia of the conjunctiva with proparacaine 0.5% drops. Patients in Group F received fentanyl 0.5 microg kg(-1) and those in Group SB were given a corresponding volume of normal saline i.v. every hour from preloaded syringes. Increases in heart rate or mean arterial pressure by more than 20% of baseline were treated with additional 0.5 microg kg(-1) i.v. fentanyl boluses in both groups. The incidence of oculocardiac reflex (OCR), need for additional analgesics, postoperative pain, and PONV were recorded for the first 24 h after surgery. RESULTS: More patients in Group F (47.96%) had moderate to severe pain in the first 24 h when compared with Group SB (31.36%) (P=0.023). The need for postoperative ibuprofen was higher in Group F (66.3%) compared with Group SB (47.95%) (P=0.012). The incidence of OCR was significantly higher in Group F (31.6%) compared with Group SB (5.1%) (P<0.001). The incidence of PONV was similar in both groups. CONCLUSIONS: Sub-Tenon's block provides more effective analgesia than i.v. fentanyl for paediatric VR surgery.

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

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: SB is a safe and superior alternative to IV fentanyl for perioperative analgesia in pediatric cataract surgery.

Effect of different anesthetic agents on oculocardiac reflex in pediatric strabismus surgery.

PURPOSE: The oculocardiac reflex (OCR) occurs frequently during pediatric strabismus surgery. The aim of this study was to assess the effects of various anesthetic regimens on the incidence of OCR during the surgery. METHODS: Two hundred and eighty children, 1 to 9 years old, undergoing elective strabismus surgery, were randomly assigned to eight groups; ketamine-sevoflurane (KS), ketamine-desflurane (KD), ketamine-propofol (KP), ketamine-remifentanil (KR), midazolam-sevoflurane (MS), midazolam-desflurane (MD), midazolam-propofol (MP), and midazolam-remifentanil (MR). No premedication was given. Anesthesia was induced using ketamine 1 mg kg(-1) or midazolam 0.15 mg kg(-1) with 66% N(2)O in O(2). Laryngeal mask airways (LMAs) were placed with rocuronium 0.5 mg kg(-1). Anesthesia was maintained with sevoflurane 2-3 vol. %, desflurane 5-6 vol. %, propofol 7-8 mg kg(-1) h(-1), or remifentanil 0.75 microg kg(-1) over 1 min, followed by a continuous infusion of remifentanil 0.5 microg kg(-1) min(-1) with 66% N(2)O in O(2). Heart rate (HR) was recorded during extraocular muscle (EOM) manipulation. OCR was defined as a reduction in HR of more than 20% induced by the traction of an EOM. RESULTS: In patients given ketamine, OCR occurred more frequently in the KP (65.7%) and KR (62.9%) groups than in the KD (29.4%) and KS (37.1%) groups (P < 0.05). In patients given midazolam, OCR occurred more frequently in the MP (54.3%) and MR (60.6%) groups than in the MD (36.4%) and MS (31.4%) groups (P < 0.05). CONCLUSION: Propofol or remifentanil anesthesia was associated with a higher incidence of OCR during pediatric strabismus surgery than sevoflurane and desflurane anesthesia, when either ketamine or midazolam was used as an induction agent.

Prevalence of and covariates associated with the oculocardiac reflex occurring in dogs during enucleation.

OBJECTIVE: To determine the prevalence of and covariates associated with the oculocardiac reflex (OCR) occurring in dogs during enucleations. SAMPLE: 145 dogs that underwent enucleation at 2 veterinary teaching hospitals between January 2010 and June 2015. PROCEDURES: Information was collected from the medical records of included dogs regarding age and body weight at hospital admission, breed (for classification of brachycephalic status), and whether they had received anticholinergic drugs or a retrobulbar nerve block (RNB) prior to enucleation. An OCR was considered to have occurred if there was a sudden decrease of ≥ 30% in heart rate from the baseline value (mean heart rate prior to the sudden decrease) during surgery in the absence of intraoperative administration of opioids or α2-adrenoceptor agonists. Associations were explored between the collected data and the prevalence of OCR by means of binomial logistic regression. RESULTS: 4.8% (7/145) of dogs had an OCR noted during enucleation. Dogs that received a preoperative RNB (n = 82) had significantly lower odds of an OCR being observed than dogs that received no preoperative RNB (OR, 0.12). No association with OCR was identified for age or brachycephalic conformation or for preoperative administration of anticholinergic drugs. CONCLUSIONS AND CLINICAL RELEVANCE: These findings suggested that preoperative administration of an RNB, but not preoperative administration of anticholinergic drugs, was associated with a lower prevalence of OCR in dogs during enucleations.

Reduction of oculocardiac reflex with Tetracaine eye drop in strabismus surgery.

INTRODUCTION: Recently, to reduce the incidence of oculocardiac reflex (OCR) in strabismus surgery, retrobulbar block and anticholinergic drugs or local anesthesia are also used. The present study evaluated the effects of Tetracaine eye drop as a topical nerve blocker on OCR during strabismus surgery. METHODS AND MATERIALS: In this randomized trial, 70 strabismus surgery candidates were randomly divided into placebo or synthetic teardrop (E) and Tetracaine eye drop (T) groups, so 3 drops of each solution were dropped in four directions of patients' eye immediately after applying anesthesia and before surgery. The incidence and severity of OCR during the stages of muscle release and incision (cutting), hemodynamic changes, the required time for OCR recovery and atropine dose were assessed. RESULTS: OCR was more seen in release phase compared to cutting phase. There were no significant differences between two group regarding the incidence and severity of OCR in the release phase (p > 0.05), but the incidence and severity of OCR in the cutting phase was more in group E than group T (p = 0.02, for both). The duration of OCR improvement (p-value = 0.74) and Atropine consumption (p-value = 0.92) did not differ between the groups. CONCLUSION: Tetracaine eye drop only reduces the incidence and severity of OCR during the incision stage of strabismus surgery.

Influence of the anaesthetic depth on the inhibition of the oculocardiac reflex during sevoflurane anaesthesia for paediatric strabismus surgery.

BACKGROUND: It remains controversial whether the anaesthetic depth as assessed by bispectral index (BIS) influences the oculocardiac reflex (OCR) during strabismus surgery. We investigated whether BIS-guided sevoflurane titration may help to optimize the anaesthetic depth for inhibition of the OCR during paediatric strabismus surgery. METHODS: Eighty-four patients (aged 2-12 yr) undergoing strabismus surgery were randomly allocated to one of the three groups (n=28 for each) according to target BIS value of 40, 50, and 60. The end-tidal sevoflurane concentration with 50% N2O/O2 was adjusted towards target BIS. The incidence of OCR and the lowest heart rate (HR) were recorded in relation to the end-tidal sevoflurane concentration. RESULTS: The incidence of OCR was higher in Group BIS-60 (71.4%) than in Groups BIS-40 (10.7%) (P<0.001) or BIS-50 (32.1%) (P=0.003), with no difference between Group BIS-40 and Group BIS-50. The lowest HR [beats min(-1), mean (sd)] during traction on the extraocular muscle was lower in Group BIS-60 [112.3 (sd 17.8)] compared with Group BIS-40 [129.3 (11.2)] (P<0.001), with no difference between BIS-40 and BIS-50 [121.4 (16.3)], and between BIS-50 and BIS-60. The end-tidal sevoflurane concentration was different between the three groups (P=0.001). CONCLUSIONS: We confirmed that OCR is relevant to the depth of anaesthesia. BIS values of 40-50 seem adequate for the inhibition of OCR. The results suggest that BIS may be a valuable tool during sevoflurane anaesthesia for strabismus surgery in children.

Effect of remifentanil on oculocardiac reflex in paediatric strabismus surgery.

BACKGROUND: Rapidly acting narcotics enhance the degree of bradycardia due to the oculocardiac reflex (OCR) elicited by extraocular muscle (EOM) tension during strabismus surgery. We evaluated and compared the effects of remifentanil and sevoflurane on OCR during paediatric strabismus surgery. METHODS: One hundred and twenty children, 1-9 years old, undergoing elective strabismus surgery, were randomly assigned to receive sevoflurane or remifentanil. No anticholinergic prophylaxis was administered. Anaesthesia was induced using ketamine 1.0 mg/kg or midazolam 0.15 mg/kg with 66% N(2)O in O(2). Laryngeal mask airways were placed with rocuronium 0.5 mg/kg. Anaesthesia was maintained with sevoflurane 2.0-3.0 vol% with 66% N(2)O in O(2) or remifentanil 0.75 mug/kg over 1 min and followed by the continuous infusion of remifentanil 0.5 mug/kg/min with 66% N(2)O in O(2). Heart rate (HR) and blood pressure (BP) were measured and compared. OCR was defined as a reduction in HR of >20% induced by traction of an EOM. RESULTS: During anaesthesia, HR and BP were maintained at a lower level in the remifentanil group than in the sevoflurane group (each, P<0.05). The mean percent change in HR (-23.3+/-17.0% vs. -11.2+/-13.0%; P<0.05) and the incidence of OCR (58.3% vs. 28.3%; P<0.05) following traction of an EOM were higher in the remifentanil group than in the sevoflurane group. CONCLUSIONS: Remifentanil enhanced the degree of bradycardia due to OCR as compared with sevoflurane during paediatric strabismus surgery.

Intravenous dexmedetomidine augments the oculocardiac reflex.

BACKGROUND: We reported that premedication with nasal dexmedetomidine was associated with a more intense oculocardiac reflex (OCR). In this study we performed an intrasubject, intravenous comparison to test our hypothesis that this alpha-adrenergic agonist potentiates the trigemino-vagal reflex. METHODS: OCR (greatest change heart rate/baseline heart rate) was prospectively monitored with 10-second, square-wave 200 g tension on the inferior rectus or other muscles during strabismus surgery. Between the first and second muscle, intravenous dexmedetomidine 0.5 µg/kg was delivered. RESULTS: All patients had no anticholinergic agents. A total 842 historic control patients (median age, 5.5 years) with no dexmedetomidine between muscles experienced the first OCR of 75% ± 24% (SD) and the second OCR of 77% ± 22%. The 33 study patients (median age, 5.6 years) experienced the first OCR 84% ± 16% and dexmedetomidine second OCR of 66% ± 25% for a bradycardia augmentation of 18% ± 19% (P < 0.01 [Mann-Whitney]). CONCLUSIONS: Similar to the effect of fentanyl, intravenous fast-push dexmedetomidine augmented the bradycardia associated with extraocular muscle traction.