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.

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.

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.

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.

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.

Dexmedetomidine Injection during Strabismus Surgery Reduces Emergence Agitation without Increasing the Oculocardiac Reflex in Children: A Randomized Controlled Trial

Objective

Dexmedetomidine is known to reduce the incidence of emergence agitation, which is a common complication after inhalational anesthesia like sevoflurane or desflurane in children. However, the dose of dexmedetomidine used for this purpose is reported variously and the most effective dose is not known. In this study, we tried to find the most effective dose of dexmedetomidine to reduce the incidence of emergence agitation in children undergoing strabismus surgery without the complications like oculocardiac reflex (OCR) or postoperative vomiting.

Methods

We randomized 103 pediatric patients aged 2–6 years and undergoing elective strabismus surgery into four groups. Anesthesia was induced with sevoflurane and maintained with desflurane. At the start of induction, dexmedetomidine, delivered at 0.25, 0.5, or 1 μg/kg, or saline was infused intravenously in the D0.25, D0.5, D1 groups, respectively. The primary outcome measure was the incidence of emergence agitation and the secondary outcome measure was the incidence of intraoperative OCR, postoperative vomiting, and desaturation events.

Results

The incidence of emergence agitation was 60, 48, 44, and 21% (P = 0.005) and the incidence of intraoperative OCR was 36, 36, 36, and 37% (P = 0.988) in the control, D0.25, D0.5, and D1 groups, respectively. And, postoperative vomiting rate and desaturation events were low in the all groups.

Conclusion

Dexmedetomidine decreased the incidence of emergence agitation without increasing intraoperative oculocardiac reflex. Dexmedetomidine delivered at 1 μg/kg was more effective at reducing emergence agitation than lower doses in children undergoing strabismus surgery under desflurane anesthesia.

Trial Registration

Clinical Research Information Service KCT0000141

Ketamine or atropine: which one better prevents oculocardiac reflex during eye surgery? A prospective randomized clinical trial

Profound bradycardia during eye surgery is a potentially serious event. In clinical practice oculo-cardiac reflex (OCR) is most often encountered during squint surgery. The objective of this study was to assess the occurrence of OCR and prove the effect of ketamine as an induction drug and anticholinergic premedication (atropine) to prevent OCR. This study comprised 90 patients (aged 4-10 years) operated for squint surgery under general anesthesia. Patients were divided into three groups. Using block randomization, each patient enrolled in one of the three groups based on organized random table prepared by statistician. Group K received ketamine as an induction drug, Group A was premedicated with intravenous injection of atropine and Group C did not receive any premedication. Patients were monitored during operation for any bradycardia or dysrhythmias. The observed data showed occurrence of 63% OCR in Group C as compared to 43% in group A and only 20% in Group K. Current study showed that induction with ketamine in the patients of squint surgery under general anesthesia definitely obtunds OCR and prevents any untoward effects of dysrhythmias during eye surgery.

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.

Comparison of desflurane with sevoflurane for the incidence of oculocardiac reflex in children undergoing strabismus surgery

BACKGROUND

The oculocardiac reflex (OCR) is frequently observed during strabismus surgery. This study was designed to evaluate and compare the effect of sevoflurane and desflurane on the incidence of OCR.

METHODS

After obtaining Institutional Review Board approval and informed consent from parents, we enrolled 237 paediatric patients, aged 2-10 yr, undergoing strabismus surgery. No premedication was given. Anaesthesia was induced with thiopental and rocuronium. Patients were randomly allocated to one of the two anaesthetic regimens. Group S (n = 123) received sevoflurane and Group D (n = 114) received desflurane, both with 60% N2O/O2 for maintenance of anaesthesia. The OCR was defined as a > or = 20% decrease in heart rate (HR) from baseline values obtained immediately before muscle manipulation. If the HR did not increase after release of muscle tension, atropine 0.01 mg kg(-1) was administered.

RESULTS

There were no significant differences between the two groups in age, sex, body weight, and the number of muscles operated upon. The mean values of baseline HR were 123 (16) min(-1) in Group S and 121 (18) in Group D (NS). The minimum HR was 106 (22) min(-1) in Group S and 103 (21) in Group D (NS). There was no difference in the incidence of OCR between sevoflurane (26.0%) and desflurane (28.0%) anaesthesia.

CONCLUSIONS

Both agents can be used safely during strabismus surgery in paediatric patients.

Single bolus of intravenous ketamine for anesthetic induction decreases oculocardiac reflex in children undergoing strabismus surgery

BACKGROUND

Oculocardiac reflex (OCR) is a major complication of pediatric strabismus surgery. The aim of the present study was to determine whether a single bolus of intravenous (i.v.) ketamine for anesthetic induction can decrease OCR in children undergoing strabismus surgery.

METHODS

One hundred and twenty healthy children undergoing strabismus surgery were allocated to three groups using double-blind randomization. Anesthesia was induced with propofol 3 mg/kg in Group P, ketamine 1 mg/kg in Group K1, or ketamine 2 mg/kg in Group K2. Anesthesia was maintained with 3% sevoflurane in 50% N(2)O/O(2) in all patients. The baseline heart rate was obtained 30 s prior to the first traction of the extraocular muscle (EOM). OCR was defined as a development of arrhythmia or a decrease of more than 20% of the baseline heart rate during EOM traction.

RESULTS

The incidence of OCR was significantly lower in the ketamine groups (4/40 and 1/40 in Group K1 and K2, respectively) compared with the propofol group (14/40).

CONCLUSION

A single bolus of i.v. ketamine 1 or 2 mg/kg for anesthetic induction results in a lower incidence of OCR than propofol when combined with sevoflurane for maintenance in children undergoing strabismus surgery.

Ketorolac as a pre-emptive analgesic in retinal detachment surgery: a prospective, randomized clinical trial

OBJECTIVE

Retinal detachment surgery is associated with a high incidence of post-operative pain, nausea and vomiting. Previous studies demonstrated a beneficial role of pre-emptive analgesia using regional anesthetic blocks for this type of surgery. The aim of the present study was to evaluate the pre-emptive analgesic effect of ketorolac in patients undergoing retinal detachment surgery under general anesthesia.

METHODS

With the approval of the Institutional Ethics Committee and written informed consent, 60 adult patients were randomized prospectively, in a double-masked manner, to receive intravenously either ketorolac 30 mg or saline placebo 30 min before operation. Pain scores at 2, 6, 12, 18 and 24 h after surgery, the number of patients requiring post-operative analgesia, total consumption of analgesics, the incidence of oculocardiac reflex as well as the incidence and severity of post-operative nausea and vomiting were recorded.

RESULTS

The ketorolac group required post-operative analgesia less frequently than the placebo group (p < 0.0001). The ketorolac group had significantly lower pain scores at all measurement time points (p < 0.001) and lower intra- and post-operative total consumption of analgesics (p < 0.01). The incidence and severity of nausea and vomiting were lower in patients given ketorolac when compared with placebo-treated patients (p < 0.05). The incidence of oculocardiac reflex was not significantly different between groups (p = 0.14).

CONCLUSIONS

The use of ketorolac for pre-emptive analgesia is effective in patients undergoing retinal detachment surgery under general anesthesia.

Association of oculocardiac reflex and postoperative nausea and vomiting in strabismus surgery in children anesthetized with halothane and nitrous oxide

BACKGROUND

Postoperative nausea and vomiting (PONV) occurs frequently after strabismus surgery. The controversy still exists regarding the association of PONV and the oculocardiac reflex (OCR). A recent study has proven that rocuronium attenuates OCR. If these two occurrences are dependent, it is expected that with the diminution of OCR, occurrence of PONV will also be reduced. The goal of this randomized, controlled study was to prove an association between OCR and PONV by attenuating OCR with 0.4 mg x kg(-1) of rocuronium and subsequently diminishing PONV if these occurrences are associated.

METHODS

A total of 119 ASA 1 children, aged between 3 and 10, undergoing surgery of the medial rectus muscle, were randomly assigned to two groups. In group R (n = 59), 0.4 mg x kg(-1) of rocuronium was administered i.v. before intubation. Group C (controls, n = 60) received no muscle relaxant. The anesthesia was induced and maintained with halothane and N(2)O/O(2) (50/50%). Chi-squared test, Fisher's exact test, t-test, and anova were used for statistical analysis; P-value <0.05 was considered statistically significant.

RESULTS

There were no differences between groups regarding patients' characteristics as well as endtidal halothane and duration of surgery and anesthesia. The occurrence of OCR was different between groups (R: 16/59, 27.1%, C: 28/60, 46.7%; P = 0.027), but not the occurrence of PONV (R: 27/59, 45.8%, C: 28/60, 46.7%; P = 0.921). There was an equal number of patients with PONV and bradycardias in both groups (R: 4/27 vs C: 4/28; P = 0.858), whereas there was different, but statistically insignificant distribution of patients (R: 3/27 vs C: 10/28; P = 0.086) with PONV and arrhythmias other than bradycardia. However, simultaneous occurrence of total OCR and PONV in the 24-h period was not different between the two groups (P = 0.964).

CONCLUSIONS

Rocuronium (0.4 mg x kg(-1)) attenuates the occurrence of OCR, but with the reduced occurrence of OCR we were not able to attenuate the occurrence of PONV, therefore the association of OCR and PONV in strabismus surgery in children anesthetized with halothane and nitrous oxide remains unclear, and if there is a link between the two, it could be related to arrhythmias and not bradycardia.

Preoperative Peribulbar Block in Patients Undergoing Retinal Detachment Surgery Under General Anesthesia: A Randomized Double-Blind Study

Retinal detachment surgery is frequently associated with significant postoperative pain and emesis in adults. In this randomized, double-blind, controlled study we sought to demonstrate that 1% ropivacaine peribulbar (PB) block in conjunction with general anesthesia (GA) improves operative conditions and postoperative analgesia compared with GA combined with subcutaneous normal saline injection into the inferior eyelid. Thirty-one patients were included in each group. Anesthesia was performed with target-controlled infusion propofol and continuous remifentanil infusion adjusted to maintain bispectral index values between 40 and 50. Postoperative analgesia included fixed-dose IV infusion of propacetamol and IV injection of nefopam via a patient-controlled analgesia device. Tramadol was infused IV as rescue medication. Demographic data were comparable between the groups and bispectral index values were maintained at the objective target. In the PB group, fewer patients presented an oculocardiac reflex (6 versus 17; P < 0.01); bleeding interfering with the surgical field was reduced (1 versus 11 patients; P < 0.01); mean time to first nefopam request was longer (148 +/- 99 versus 46 +/- 58 min; P < 0.01); mean nefopam consumption was diminished during the first 6 h after tracheal extubation (18.9 +/- 13.9 versus 28.5 +/- 14.7 mg; P < 0.05); immediate postoperative pain scores were lower; and fewer patients required rescue medication (5 versus 23; P < 0.01). The two groups were similar with respect to the incidence of postoperative nausea and vomiting. Overall, PB block combined with GA improved operating conditions and postoperative analgesia in retinal detachment surgery.

Anticholinergic premedication for prevention of oculocardiac reflex during squint surgery

BACKGROUND

Profound bradycardia during eye surgery is potentially serious event. In clinical practice this Oculocardiac Reflex (OCR) is most often encountered during squint surgery. The objective of this study was to assess the occurrence of OCR and prove the effect of anticholinergic premedication (atropine) to prevent OCR.

METHODS

This study comprises of sixty patients (age 2-30 years) operated for squint surgery under general anaesthesia. Cases were divided into two groups of thirty each. Group 1 was premedicated with intravenous injection of atropine and Group 2 did not receive any premedication. Patients were monitored during operation for any bradycardia or dysrhythmias.

RESULTS

The observed data showed occurrence of 70% OCR in Group 2 as compared to only 10% in Group 1. Severe bradycardia in 40% cases of Group 2 needed intervention by IV injection of atropine.

CONCLUSION

Our study showed that atropine premedication in the patients of squint surgery under general anaesthesia definitely obtunds OCR and prevents any untoward effects of dysrhythmias during eye surgery.

Effects of Subtenon Anesthesia Combined With General Anesthesia on Perioperative Analgesic Requirements in Pediatric Strabismus Surgery

BACKGROUND AND OBJECTIVES

Pediatric strabismus surgery leads to undesirable intraoperative and postoperative side effects that include pain, postoperative nausea and vomiting (PONV), and oculocardiac reflex (OCR). We hypothesized that subtenon anesthesia performed before the start of surgery and combined with general intravenous anesthesia would reduce these adverse effects.

METHODS

Forty children (2.5 to 6 years of age, ASA status I to II) were prospectively randomized to receive either subtenon bupivacaine 0.5% or a saline injection before the beginning of surgery in a double-blind manner. Perioperative analgesic requirements, pain scores (CHEOPS scale), hemodynamics, and incidence of OCR and PONV were compared.

RESULTS

Postoperative pain scores were lower (P < .001) at removal of the laryngeal mask and 30 minutes later in the bupivacaine group. Intraoperative and postoperative analgesic requirements were significantly reduced in this group (P < .01). The incidence of OCR and PONV were also significantly decreased (P < .01). Intraoperative values of blood pressure were significantly higher in the saline group at 20 minutes (P < .02).

CONCLUSION

We conclude that preoperative subtenon bupivacaine 0.5% compared with a saline injection contributed to reduction of perioperative pain and undesirable side effects in pediatric strabismus surgery performed under general anesthesia.

Rocuronium attenuates oculocardiac reflex during squint surgery in children anesthetized with halothane and nitrous oxide

BACKGROUND

The oculocardiac reflex (OCR) may be activated during squint surgery. The aim of this study was to test whether rocuronium 0.4 mg kg(-1) could reduce the frequency of OCR, and also whether a single dose of succinylcholine 1 mg kg(-1) could affect the frequency of OCR during anesthesia with halothane in a nitrous oxide/oxygen mixture.

METHODS

A total of 161 ASA I children, 3-10 years old, undergoing elective surgery of the medial rectus muscle (MRM) were randomly assigned to three groups. Group R (n = 51), received 0.4 mg kg(-1) of rocuronium intravenously before endotracheal intubation. Group S (n = 58) received 1 mg kg(-1) of succinylcholine. Group C (controls, n = 52) received no relaxant. Oculocardiac reflex was defined as a reduction in heart rate (HR) > or = 15% and/or the appearance of any other arrhythmias, during manipulation of the MRM. Analysis of variance (anova), chi-squared, Kruskal-Wallis, and Student's t-tests were used for statistical analysis; P< 0.05 was considered statistically significant.

RESULTS

In group R, OCR occurred in 15/51 (29%) of children, in group S in 31/58 (53%), and in group C in 23/52 (44%) (chi2 = 6.46, P = 0.049). In group R, the incidence of arrhythmias such as nodal rhythms, supraventricular and ventricular premature beats was 6%, compared with 22% in group S and 19% in group C (chi2 = 6.01, P = 0.040). However, there was no reduction in the occurrence of bradycardia (chi2 = 0.16, P = 0.924).

CONCLUSION

Rocuronium reduced the frequency of OCR, mainly by reducing the incidence of supraventricular and ventricular premature beats.

The profound augmentation of the oculocardiac reflex by fast acting opioids

BACKGROUND

Trigemino-vagal bradycardia elicited by tension on an extraocular muscles (oculocardiac reflex; OCR) is a hazard for strabismus surgery patients. OCR can be reduced by anticholinergic medications and regulating the depth of anesthesia. We investigated the influence of narcotic agents as a routine part of general anesthesia for strabismus surgery in adults and children.

METHOD

From August, 1992 through September, 2000, 1275 patients undergoing extraocular muscle surgery were prospectively studied during 10 second, 200 gram square wave tension on gently isolated rectus muscles. The anesthetic agents, gas concentrations, and patient age were recorded. Patients receiving an anticholinergic agent and reoperated cases were excluded, yielding 1029 study cases. 849 received no narcotic as a part of induction. Two groups of patients were given no opiate before the first inferior rectus muscle was pulled. A narcotic was administered IV 5 minutes before the second inferior rectus was pulled. One group of 49 received fentanyl 0.15 uL/Kg and the second group of 12 received meperidine 1 mg/kg.

RESULTS

Faster acting intravenous induction opioids had a profound augmenting effect on the degree of oculocardiac reflex. Compared to no narcotic, the OCR was increased most by remifentanyl (p less than .0001), then sufenta (p=.02), and fentanyl (p less than .0001). Induction morphine had no appreciable effect on the OCR (p=.9). For the 49 patients with IV fentanyl delivered between the first OCR and second OCR, a significant increase occurred (p=.003). This increase in %OCR was not correlated with a change in inhalational gas concentration (p=.9), CO2 concentration (p=.6) or age (p=.12). For the 12 patients given demerol between the first and second rectus tension, no significant OCR change occurred (p=.7). The OCR was greatest for inferior rectus, then superior rectus, then medial rectus, and least for lateral rectus. (See text for details.)

CONCLUSION

In the absence of anticholinergic blockade, rapidly acting narcotics enhance the degree of bradycardia due to the OCR elicited by controlled extraocular muscle tension during strabismus surgery. Some opioids had the same augmenting magnitude as the blocking effect of IV anticholinergic medication. Meperidine, which has some anticholinergic characteristics, neither blocked nor augmented the OCR.

The attenuating effect of intraglossal atropine on the oculocardiac reflex

INTRODUCTION

Bradycardia during strabismus surgery is reduced better by intravenous than by intramuscular (deltoid) anticholinergics, but recent studies suggest that injection into the tongue works faster than into the deltoid. We sought to study this using the suppression of the oculocardiac reflex during eye surgery as a parameter.

METHODS

804 children and adults underwent calibrated extraocular muscle tensioning during controlled, inhalational general anesthesia. A systemic anticholinergic agent was distributed by different routes to patient-subject sub-groups: preoperative oral, or induction intravenous, intramuscular (deltoid) and intraglossal (submucosal at the base of the tongue). A large control group received no anticholinergic.

RESULTS

The control group had an oculocardiac reflex averaging 17.2% heart rate reduction (bradycardia), 6% of whom had greater than a 50% heart rate reduction. This oculocardiac reflex bradycardia was reduced to only a 6.7% heart rate reduction by oral and intradeltoid routes and was essentially eliminated by both intravenous (-2.3%) and intraglossal (-0.9%) routes.

CONCLUSION

Intraglossal atropine is an effective alternative for oculocardiac reflex prophylaxis when intravenous access is not readily available in strabismus surgery. The intraglossal route is in fact slightly more effective in this regard that the intravenous route per se.

Usefulness of pre-emptive peribulbar block in pediatric vitreoretinal surgery: a prospective study

BACKGROUND AND OBJECTIVES

Vitreoretinal (VR) surgery with or without scleral buckling is associated with significant postoperative pain and emesis in adults, and recent studies have addressed the effect of retro or peribulbar block on these parameters. VR surgery in children has received little attention regarding the incidence of pain and emesis, and the role of regional anesthesia in modifying these parameters. In this study, we compared peribulbar block with conventional opioid analgesia in children undergoing VR surgery.

METHODS

In a prospective, randomized, single-blind study, 85 children (ages 6 to 13 years) were allocated to receive peribulbar block (n = 42) or intravenous meperidine 1 mg/kg (n = 43) after induction of general anesthesia. Parameters compared were: intraoperative incidence of oculocardiac reflex and requirement for additional analgesic; postoperative pain intensity; incidence of postoperative emesis; time to first analgesic, total number of postoperative analgesic supplements; and parental assessment of the child's postoperative comfort at 24 hours.

RESULTS

The incidence of intraoperative oculocardiac reflex was significantly less in the peribulbar group (P =.0001). Significantly more children receiving peribulbar block were pain free on awakening (P =.0004) and throughout the postoperative period. The number of children requiring opioid was significantly lower with peribulbar block (P =.008), and a significant number of children did not vomit throughout the postoperative period (P =.001).

CONCLUSIONS

Peribulbar block appears to be a safe and clinically superior alternative to intravenous opioid for pediatric VR surgery.

Effect of different anaesthetic regimes on the oculocardiac reflex during paediatric strabismus surgery

The oculocardiac reflex (OCR) is induced by mechanical stimulation and therefore is frequently encountered during strabismus surgery. This study was designed to determine how various anaesthetic regimes modulate the haemodynamic effects of the OCR during paediatric strabismus surgery. Thirty-nine patients (4-14 years, ASA I) were randomized to one of four anaesthetic regimes: group P: propofol (12 mg.kg(-1).h(-1)) and alfentanil (0.04 mg.kg(-1).h(-1)); group S: sevoflurane 1-1.2 MAC in 30% O(2)/70% N(2)O; group K: ketamine racemate (10-12 mg. kg(-1).h(-1)) and midazolam (0.3-0.6 mg.kg(-1).h(-1); group H: halothane 1-1. 2 MAC in 30% O(2)/70% N(2)O. Electrocardiogram (ECG), beat-to-beat heart rate (HR) and blood pressure (BP) changes were measured during and after a standardized traction was applied to an external eye muscle (4-6 Newton, 90 s). OCR was defined as a 10% change in HR induced by traction. OCR occurred in 77% of patients. Whereas virtually all patients in the P, H and S groups developed OCR, only 22% developed it in group K. Median HR change in group P (-37 bpm) was significantly greater (P < 0.05) than in group H (-17 bpm) or group K (-7 bpm). Median BP change in group K (+10 mmHg) was significantly different (P < 0.05) from group H (-5 mmHg), group S (-3 mmHg) and group P (-8 mmHg). Atrioventricular rhythm disorders were significantly more frequent in group P compared with group K (P < 0.02). Respiration-induced sinus dysrhythmia was significantly less frequent (P < 0.001) in group K (0%), compared with group P (100%), group H (56%) and group S (55%). Of the anaesthetic techniques studied, ketamine anaesthesia is associated with the least haemodynamic changes induced by OCR during strabismus surgery in paediatric patients.

Electrocardiographic changes during subconjunctival injections

Electrocardiographic changes were investigated in 53 patients during subconjunctival drug injections. Decrease in heart-rate of more than 10% or arrhythmia was observed in 25 (47.2%) of the patients, who were considered to have a positive oculocardiac reflex. In the control group of 35 patients, only 3 (8.6%) were found to have a significant decrease in heart rate during blood sampling from antecubital vein (p = 0.000). Young age was a significant risk factor for oculocardiac reflex during injections (p = 0.01). Patient gender, verbal pain score, satiety, experience of periocular injections, injected drug type were not found to be risk factors. All patients with oculocardiac reflex were asymptomatic; however, it is still wise to have emergency supplies ready for any circulatory derangement during subconjunctival injections.

Effects of peribulbar bupivacaine as an adjunct to general anaesthesia on peri-operative outcome following retinal detachment surgery

Sixty premedicated, ASA physical status I or II patients weighing > 25 kg scheduled for elective retinal detachment repair were randomly assigned to receive either peribulbar block with 10 ml of 0.25% bupivacaine (block group) or intravenous morphine 150 microg.kg-1 (morphine group), prior to the induction of general anaesthesia (n = 30 in each group). Patients were evaluated for intra-operative oculocardiac reflex, peri-operative pain relief, recovery from anaesthesia and postoperative nausea and vomiting. Apart from significantly reducing the incidence of oculocardiac reflex (30% vs. 70%, p = 0.0019), peribulbar bupivacaine also attenuated the severity of the reflex. Postoperative pain relief was superior in the block group. More block group patients had the maximum recovery score in the immediate postoperative period (80% vs. 27%, p < 0. 0001) and they achieved complete recovery significantly faster than the morphine group (17.3 (14.7) min vs. 66.7 (29.7) min, p < 0.0001). The incidence (40% vs. 77%, p = 0.004) and severity of postoperative nausea and vomiting were significantly less in the block group. In summary, peribulbar bupivacaine, when administered together with general anaesthesia, attenuated oculocardiac reflex, provided comparable intra-operative and superior postoperative analgesia, resulted in significantly earlier and better recovery from anaesthesia, and significantly reduced the incidence and severity of postoperative nausea and vomiting.

[Effects of sevoflurane versus propofol on oculocardiac reflex--a comparative study in 180 children]

Oculocardial reflex (OCR) occurs particularly through manipulation of the medial rectus muscle and results in a bradycardic arrhythmia. In children the incidence is between 60 and 80%. After using sevoflurane in clinical practice, the absence or non-occurrence of this reflex was observed. The data of 180 healthy children aged between four and 14 years who had to undergo strabismus surgery under general anaesthesia were analysed: group I (n = 92), group II (n = 88). All children received standard premedication with midazolam, no anticholinergic drugs were administered. During narcosis, analgesia was maintained routinely with alfentanil. In group I sevoflurane was inhaled for hypnosis and in group II propofol was injected as intravenous hypnotic drug. The depth of anaesthesia was adjusted according to clinical criteria. To compare both groups, heart rate (HR) was determined before, during and after surgical intervention. OCR was defined as a heart rate declining by more than 20% from the initial HR.OCR is described in all methods of general anaesthesia. Under sevoflurane the occurrence of the reflex was significantly (p < 0.05) reduced to 14% of all patients as compared to 75% in patients who received a propofol infusion. Sufficient reflex reduction according to the depth of narcosis under sevoflurane in combination with the sympathomimetic effects of this drug could therefore be discussed as a reason for its positive effects. In our opinion, the use of sevoflurane should be considered as an option for general anaesthesia in strabismus surgery.

Reduction of postoperative nausea and vomiting by dimenhydrinate suppositories after strabismus surgery in children

Although dimenhydrinate has been used for treatment and prevention of postoperative nausea and vomiting (PONV) since the fifties, there have been few controlled studies about its efficacy. We performed a double-blinded study of 301 children aged 4 to 10 yr who underwent strabismus surgery. Preanesthetic medication with midazolam (0.5 mg/kg) as well as application of either dimenhydrinate suppositories or a placebo preparation was performed 30 min before the induction of anesthesia. Anesthesia was induced with thiopentone (5-10 mg/kg) and vecuronium (0.1 mg/kg) and maintained with halothane (1%-2%) in N(2)O/O(2) (65%/35%). The incidence of PONV, requirements for rescue dimenhydrinate, and time to recovery were recorded. The overall incidence of PONV was 60.1% in the placebo group and 30.7% in the dimenhydrinate group. In the dimenhydrinate group, children had to be observed in the recovery room significantly longer than those in the placebo group. Children having received dimenhydrinate were discharged from the recovery room with lower arousal scores. We conclude that the rectal administration of dimenhydrinate is effective for the prevention of PONV, although the sedative effect may require longer postoperative monitoring.

IMPLICATIONS

We performed a double-blinded, randomized study to investigate the effects of prophylactic rectal dimenhydrinate application on postoperative nausea and vomiting in children undergoing strabismus surgery. In comparison with placebo, dimenhydrinate reduced the incidence of postoperative vomiting from 60.1% to 30.7%.

A comparison of the incidence of the oculocardiac and oculorespiratory reflexes during sevoflurane or halothane anesthesia for strabismus surgery in children

We examined changes in the cardiorespiratory system of small children during surgical correction of strabismus with a laryngeal mask airway and spontaneous respiration with sevoflurane or halothane inhaled anesthesia. Fifty-one children, 1-7 yr old, having outpatient strabismus correction were randomized to sevoflurane (S) or halothane (H) in 66% nitrous oxide at 1.3 minimum alveolar concentration. Children breathed spontaneously through a laryngeal mask airway and were not pretreated with anticholinergics. The oculocardiac reflex (OCR), defined as a 20% decrease in heart rate (HR) from baseline, dysrhythmias, or sinoatrial arrest concomitant with ocular muscle traction occurred less frequently with sevoflurane than with halothane (S 38%, H79%, P = 0.009). The baseline HR was higher with sevoflurane (S 114 +/- 13 bpm, H 101 +/- 15 bpm, P = 0.002). The lowest HR occurred with halothane (S 95 +/- 22 bpm, H 73 +/- 19 bpm, P = 0.001). The incidence of dysrhythmias was higher in the halothane group (S 4%, H 42%, P = 0.004). Reductions in minute ventilation and PETCO(2) accompanied OCRs. Airway irritability was present with halothane only (S 0, H 3). Eleven children, of whom the majority had received halothane, required measures to correct SpO(2) < 95% or PETCO(2) > 60 mm Hg during maintenance anesthesia (S 11%, H 32%). Sevoflurane may be a more suitable anesthetic than halothane for operations involving traction on the ocular muscles with spontaneous respiration in children because of reduced incidence of OCR, airway irritability, and ventilatory disturbances.

IMPLICATIONS

Some children experience a sudden slowing of the heart and impaired breathing when the surgeon pulls on the eye muscles during squint operations under anesthesia. Sevoflurane, a recently developed anesthetic vapor, may reduce this problem when compared with the established vapor halothane.

Incidence of nausea and vomiting in children after strabismus surgery following desflurane anaesthesia

In a prospective, randomized parallel study, 60 ASA I-III children aged 1-17 years, scheduled for elective strabismus surgery, were anaesthetized with desflurane without prophylactic antiemetic medication. The objective of the study was to determine the incidence of postoperative nausea and vomiting after general anaesthesia with desflurane. To decide whether nitrous oxide further influences these symptoms, the patients were randomly assigned to two groups of 30 patients each. One group received desflurane in oxygen/air and a second group received desflurane in oxygen/nitrous oxide. In all children, after intravenous induction and tracheal intubation, anaesthesia was administered as minimal flow anaesthesia with oxygen and nitrous oxide or air according to the random plan. The patients were observed for 48 postoperative hours until their discharge from the ward. The overall incidence of nausea was found to be 37%, and vomiting was seen in 32% of all patients. No statistical correlation was found between the incidence of postoperative emesis and the administration of nitrous oxide or the duration of general anaesthesia. Instead, the incidence of vomiting was 2.5-fold higher when surgery was performed on both eyes compared with one eye. The relatively low incidence of postoperative nausea and vomiting, as well as the quick recovery from anaesthesia, permitting an early discharge from the postoperative care unit to the ward, show desflurane to be a suitable volatile anaesthetic in strabismus surgery in children.

Propofol-nitrous oxide versus sevoflurane-nitrous oxide for strabismus surgery in children

Vomiting is a common problem following strabismus surgery. We compared the effects of propofol-N2O and sevoflurane-N2O on the incidence of oculocardiac reflex and postoperative nausea and vomiting. Forty unpremedicated children, aged 3-15 years were randomly assigned to two groups of 20 patients. In group 1, anaesthesia was induced and maintained with propofol infusion (173 +/- 41 micrograms.kg-1.min-1). In group 2, anaesthesia was induced with N2O (66%) in O2 and incremental sevoflurane via face mask and maintained with sevoflurane. Both groups received 66% N2O in O2 throughout surgery. The overall incidence of vomiting and antiemetic requirement in the first 24 h was significantly higher in sevoflurane-N2O group than propofol-N2O group (P < 0.05). The propofol-N2O group had significantly more episodes of oculocardiac reflex than sevoflurane-N2O group (P < 0.05). Propofol-N2O anaesthesia results in a significantly lower incidence of postoperative vomiting, yet a significantly higher incidence of oculocardiac reflex.

Alfentanil decreases the excitatory phenomena of sodium methohexital

STUDY OBJECTIVE

To evaluate the effects of alfentanil or lidocaine on the excitatory phenomena (myoclonus, cough, hiccough) caused by methohexital anesthesia and on the hemodynamic changes induced by retrobulbar block.

DESIGN

Prospective, randomized, placebo-controlled, double-blind study.

SETTING

University-affiliated, tertiary-care hospital.

PATIENTS

60 ASA physical status II and III patients who were admitted for elective cataract extractions and intraocular lens implantations.

INTERVENTIONS

Patients were randomly assigned to one of three groups. After adequate preoxygenation in the holding area, Group 1 received alfentanil 5 micrograms/kg intravenously (i.v.), Group 2 received lidocaine 1 mg/kg i.v. and Group 3 received the placebo (saline) i.v. Immediately after the bolus injection of the study solution, sodium methohexital 1.5 mg/kg was injected i.v. over 30 seconds. As soon as the eyelid reflex was lost, the retrobulbar block was placed over 5 seconds.

MEASUREMENTS AND MAIN RESULTS

Occurrences of excitatory phenomena were recorded by an independent observer who was blinded as to treatment allocation. Other side effects such as oculocardiac reflex, nausea, vomiting, itching, or chest wall rigidity were recorded. Vital signs were recorded at baseline and 1, 3, and 5 minutes after placement of the block. In the alfentanil group, the incidence of myoclonus or cough was significantly less than in the lidocaine or placebo groups. Alfentanil also decreased systolic and diastolic blood pressure significantly at 1, 3, and 5 minutes after retrobulbar block. Changes in heart rate were not significantly different from baseline.

CONCLUSION

A small dose of alfentanil (5 micrograms/kg i.v.) decreases myoclonus and cough induced by sodium methohexital anesthesia i.v., resulting in improved quality of induction of anesthesia. Alfentanil also attenuates the cardiovascular responses caused by placement of a retrobulbar block.

Oculocardiac reflex and postoperative vomiting in paediatric strabismus surgery. A randomised controlled trial comparing four anaesthetic techniques

BACKGROUND

Oculocardiac reflex (OCR) and postoperative vomiting are major complications of paediatric strabismus surgery.

METHODS

Children (3-16 yr) undergoing elective strabismus surgery as inpatients were randomly allocated to four anaesthetic techniques: (A) thiopentone induction and isoflurane maintenance; (B) as (A) plus ondansetron 5 mg x m(-2) i.v.; (C) propofol induction and maintenance; (D) as (C) plus lignocaine 2 mg x kg(-1) i.v. All children received prophylactic atropine 0.02 mg x kg(-1) and alfentanil. Nitrous oxide was omitted.

RESULTS

Data on 157 children were analysed. The cumulative incidence of vomiting within 6 and 24 h after surgery with thiopentone-isoflurane was 26% and 46%, respectively. Adding ondansetron decreased the incidence to 8% and 33%, respectively. This improvement was significant within 6 h only; the number-needed-to-treat was 5.5 (95% CI 2.9-46). Propofol was not different from thiopentone-isoflurane. The addition of lignocaine to propofol was of no benefit. The risk of an OCR was significantly increased with propofol (incidence 40%) compared with isoflurane (14%); the number-needed-to-harm was 3.9 (95% CI 2.6-8).

CONCLUSIONS

Thiopental-isoflurane-air/O2-alfentanil resulted in a moderate risk of vomiting. Adding ondansetron significantly decreased this risk, but 6 children have to be treated for one to benefit in the early postoperative period. Propofol and propofol-lignocaine showed no benefit on vomiting but significantly increased the risk of an OCR despite high-dose prophylactic atropine.

[Effect of locally applied lidocaine on expression of the oculocardiac reflex]

INTRODUCTION

The oculocardiac reflex causes severe bradycardic arrhythmias and is a frequent complication during surgical manipulation at the medial rectus muscle. The purpose of this study was to evaluate the influence of lidocaine administered topically on the muscle on the incidence of the oculocardiac reflex.

PATIENTS AND METHODS

After obtaining informed consent, 140 patients with strabism or retinal surgery were included in this study. All patients received standard premedication and anesthesia and were randomly assigned to two groups. Patients (n = 70) randomly assigned to the first group received 1 mg/kg lidocaine applied topically to the muscle after opening the conjunctiva. Individuals in the placebo group received the same volume of saline (0.9%). Surgical stimulation occurred 5 min after administration of the drug. The study parameters (blood pressure/heart rate) were recorded before and after stimulation of the oculocardiac reflex caused by routine surgical preparation.

RESULTS

Topical administration of lidocaine reduced the incidence of the oculocardiac reflex (86.1% vs 37.1%), and the frequency of severe bradycardiac arrhythmias was also significantly reduced (40 vs. 2.9%). Cardiac arrest for longer than 10 s did not occur in the lidocaine group. In the control group this phenomenon was observed in 14.8%.

Attenuation of the oculocardiac reflex after topically applied lignocaine during surgery for strabismus in children

The effect of topical lignocaine applied to the eye muscles, on the incidence of the oculocardiac reflex during squint surgery of the medial rectus was investigated in 56 healthy children aged between 3-14 years. Three groups were studied. One (n = 16): stimulation of the reflex without lignocaine; 2 (n = 10): stimulation of the reflex after topical administration of 1 mg kg-1 lignocaine 2% to the medial part of the eye after induction of anaesthesia; 3 (n = 30): stimulation of the oculocardiac reflex without, and after a 5 min interval under the influence of lignocaine. Topical administered lignocaine significantly attenuated the OCR (105 vs. 68 bpm group II vs. group 1:82 vs. 63 bpm in group III). Severe bradycardiac rhythm disturbances, in particular cardiac stand-still, were not observed after lignocaine had been applied. Systemic side effects of lignocaine were not seen.

Anticholinergic prophylaxis does not prevent emesis following strabismus surgery in children

One hundred and twenty-one children were studied in this prospective, randomized double-blind, placebo-controlled comparison of the effectiveness of anticholinergic prophylaxis for the prevention of emetic symptoms following strabismus surgery. The children were allocated to three groups, to receive placebo (n = 40), glycopyrrolate (n = 40) or atropine (n = 41). The incidence of intraoperative oculocardiac reflex (OCR) and of postoperative emetic symptoms for 24 h was recorded. The incidence of OCR was 55% in the placebo group compared with 5% and 2% in the glycopyrrolate and atropine groups respectively (P < 0.05). Thirty percent (12/40) of patients in the placebo group, 25% (10/40) in the glycopyrrolate group, and 22% (9/41) in the atropine group experienced nausea and/or vomiting (difference not significant). It is concluded that prophylactic administration of anticholinergic agents during strabismus surgery in children despite being effective against the occurrence of the oculocardiac reflex, does not reduce the incidence of emetic symptoms.

[Use of Diprivan in ophthalmology]

Propofol may be used in several ways: As an induction agent for general anaesthesia. Maintenance is ensured by a halogenated anaesthetic, an opioid and a muscle relaxant, in an intubated and ventilated patient. It is interesting to administer propofol simply for induction, because of the rapid recovery. As the main anaesthetic agent, ensuring induction and maintenance of anaesthesia, combined with an opioid and a muscle relaxant, particularly during total intravenous anaesthesia. The patient is intubated and ventilated mechanically. To complement retrobulbar or peribulbar anaesthesia, given just before administration of the local anaesthetic, to produce amnesia of the injection. Small doses of propofol are then sufficient (0.3 to 1.5 mg.kg-1). Some authors continue to administer propofol throughout the procedure, with the patient breathing spontaneously. In young adults, a dosage regimen of 2.5 mg.kg-1 for induction, followed by an infusion or preferably a syringe pump administration of 6 to 12 mg-1.kg-1, ensures calm induction and rapid recovery. A gradual decrease in the administration rate: 10 mg.kg-1.h-1 for 10 min. 8 mg.kg-1.h-1 for 10 min, then 6 mg.kg-1.h-1, has been suggested. In the elderly, over 60 years of age, reducing the dose of propofol by 50% limits haemodynamic effects. Prior vascular fluid loading with 5 to 10mL.kg-1 is preferred by some authors. Administration of 0.5 to 1.5 mg.kg-1 by slow injection or titration, while monitoring haemodynamic effects, decreases side effects. Maintenance of anaesthesia with a dose range of 3 to 9 mg.kg-1.h-1 of propofol, according to surgical stimuli and haemodynamic stability, is recommended. In children between 3 and 10 years of age, larger doses are required, over 3 mg.kg-1 in 20 seconds, virtually without excitatory phenomena. In the absence of premedication, a dose of 4 mg.kg-1 is recommended.(ABSTRACT TRUNCATED AT 250 WORDS)

[Emesis and the oculocardiac reflex. Drug prophylaxis with droperidol and atropine in children undergoing strabismus surgery]

Although droperidol is often used to prevent emesis, vomiting is still common in children undergoing strabismus surgery. METHODS. One hundred children aged 3 to 12 years admitted for strabismus surgery were enrolled in a randomised, double-blind study to investigate the influence of the timing of the administration of droperidol (75 micrograms/kg i.v.) and the effect of atropine (10 micrograms/kg i.v.) on postoperative vomiting and the occurrence of the oculocardiac reflex (OCR). Each child was prospectively assigned to one of the following groups: Group A: atropine and droperidol before the beginning of surgery (n = 25); Group B: atropine before the beginning, droperidol after completion of surgery (n = 25); Group C: no atropine, droperidol before the beginning of surgery (n = 25); Group D: no atropine, droperidol after completion of surgery (n = 25). After oral premedication with 0.4 mg/kg midazolam, anaesthesia was induced via a face mask by inhalation of halothane, nitrous oxide, and oxygen and 1 mg/kg succinylcholine was given to facilitate tracheal intubation. Gastric contents were aspirated by a gastric tube at the end of the operation. Vomiting and retching were recorded for 24 h; recovery from anaesthesia was assessed by a modified Steward score. RESULTS. The four groups were comparable regarding age, sex, body weight, duration of anaesthesia, and number of repaired eye muscles. Patients receiving droperidol before and after the end of surgery had a similar incidence of vomiting (groups A and C 60% vs. groups B and D 50%). There was no significant difference in the number of patients vomiting between groups A and B (58%) and groups C and D (52%). The incidence of the OCR was lower in the patients premedicated with atropine (18% vs. 60%, P < 0.01). There was no statistical relationship between the occurrence of the OCR and post-operative emesis. Younger children (3 to 6 years) vomited more often than older ones (7 to 12 years). The incidence of the OCR was higher in patients with more than two eye muscles repaired than in others. Recovery scores were slightly lower in patients with droperidol after completion of surgery; postoperative recovery times did not differ significantly between the study groups. CONCLUSIONS. The timing of the administration of droperidol (75 micrograms/kg) had no influence on postoperative vomiting. The application of atropine (10 micrograms/kg) prior to surgery did not influence vomiting after strabismus surgery. Atropine (10 micrograms/kg) reduced the incidence of the OCR significantly. There was no statistical relationship between the occurrence of the OCR and postoperative vomiting.

Is there a cholinergic and an adrenergic phase of the oculocardiac reflex during strabismus surgery?

We investigated the counterregulatory effect of the oculocardiac reflex (OCR) in 25 infants and children during strabismus surgery under three experimental conditions. In group 1, a series of measurements were recorded when the OCR was elicited by traction. The beat-to-beat heart rate reduction ranged from -26 to -64 beats/min (median: -46 beats/min). Constant traction increased heart rate in all patients from +23 to +50 beats/min (median: +30.5; P < 0.001). After a sudden release of the stimulation, heart rate rose further from +6 to +40 beats/min (median: +15; P < 0.001). In group 2, atropine (0.01 mg/kg) was administered 3-4 min prior to the same manipulations as in group 1. Constant traction changed heart rate from -1 to +20 beats/min (median: +4.5; P < 0.01). In group 3, a retrobulbar blockade suppressed the OCR and the counterregulation completely. These findings indicate that there is an active counterregulatory process which maintains heart rate during traction at the extraocular muscles after the bradycardic reflex has been initiated. The bradycardia and the counterregulation may be referred to as cholinergic and adrenergic phrases of the OCR. Atropine eliminates the cholinergic phase. Our study indicates that there may be receptors and afferent fibres for both phases, which can be blocked by local anaesthetics.

Propofol-nitrous oxide versus thiopental sodium-isoflurane-nitrous oxide for strabismus surgery in children

STUDY OBJECTIVES

To assess the quality of anesthesia and recovery and the frequency of postanesthetic retching and vomiting with propofol anesthesia for pediatric strabismus surgery.

DESIGN

Randomized, open, prospective study.

SETTING

University hospital.

PATIENTS

Forty children scheduled for strabismus surgery.

INTERVENTIONS

The 40 patients were all premedicated with oral midazolam and received intraoperative opioids. They were divided into two groups: Twenty children received propofol at induction, followed by maintenance of anesthesia with propofol infusion and an oxygen-nitrous oxide (O2-N2O) mixture. The other 20 children received thiopental sodium at induction, followed by isoflurane in an O2-N2O mixture.

MEASUREMENTS AND MAIN RESULTS

At induction, pain and spontaneous movements were seen significantly more with propofol (11 of 20 vs. 0 of 20 for pain and 13 of 20 vs. 0 of 20 for spontaneous movements; p < 0.001), whereas thoracic rigidity was observed only with thiopental sodium (4 of 20). During maintenance of anesthesia, significantly more oculocardiac reflexes were seen with propofol (10 of 20 vs. 3 of 20; p < 0.02). The interval between termination of anesthesia and extubation was significantly shorter with propofol (13 minutes vs. 16 minutes; p < 0.02). For the first 24 hours after surgery, significantly less retching and vomiting were observed in the propofol group (4 of 20 vs. 11 of 20; p = 0.02).

CONCLUSIONS

Propofol induction and maintenance of anesthesia for strabismus surgery in children significantly lowers the frequency of postanesthetic retching and vomiting, but propofol is associated with pain and spontaneous movements at induction and a high frequency of oculocardiac reflexes during maintenance infusion.

Peribulbar anaesthesia: failure to abolish the oculocardiac reflex

Peribulbar anaesthesia is a form of regional anaesthesia which has been used with increasing popularity in cataract surgery. Recently indications for its use have been extended to include surgery for vitreo-retinal disease and strabismus. This study shows that in nine of 11 patients in whom the oculocardiac reflex was stimulated by traction on an extra-ocular muscle, peribulbar anaesthesia failed to abolish the reflex. In each of these patients, the reflex manifested as a bradycardia. In one subject, the bradycardia was profound, showing no QRS complex for five seconds. We recommend that cardiac rhythm be monitored throughout procedures performed under peribulbar anaesthesia, and that a vagolytic agent be available for immediate use.

Effects of atracurium and pancuronium on the oculocardiac reflex in children

The authors compare the effect of two muscle relaxants, atracurium and pancuronium, on the bradycardia resulting from the oculocardiac reflex during eye surgery for strabismus in children. Two groups, each composed of 15 children, received either pancuronium or atracurium during strabismus operations. Heart rate and rhythm were observed at several points during the operations, and the changes that occurred in the two groups were compared. We found that the incidence and severity of the bradycardia, the incidence of dysrhythmias, and the need for atropine administration were significantly greater in the atracurium group than in the pancuronium group.

Prevention of oculocardiac reflex (O.C.R) during extraocular muscle surgery

In the present study the effectiveness of intravenous atropine sulphate which blocks the peripheral muscarinic receptors at the heart and retrobulbar xylocaine hydrochloride which blocks the conduction at ciliary ganglion on the afferent limb of OCR was studied during strabismus surgery. The study was conducted on fifty three patients of either sex having squint of more than ten years duration. The patients were randomly allocated into four groups. No preanaesthetic medication with atropine or retrobulbar block with xylocaine was given in control group of patients. In the second group, only preanaesthetic medication with atropine was given; while in the third group only retrobulbar injection of xylocaine was given five minutes before operation. In the last group both atropine as preanaesthetic medication and xylocaine as retrobulbar block were given. The electrocardiographic recordings were taken before and throughout the operative procedure. It was interesting to note that in the group where atropine and xylocaine were used none of the patients exhibited activation of OCR. Results have been discussed.

Reflex bradycardia in facial surgery

Traction on, or stretching of, any structure innervated by the trigeminal nerve can cause reflex slowing of the pulse, inappropriately known as the "oculocardiac reflex" because it is well-known to result from traction on the extra-ocular muscles. This phenomenon can cause problems in surgery of the face and cranium as well as the orbit. An awareness of its management can obviate morbidity and mortality. An account of the phenomenon, its treatment and illustrative case histories are presented.