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.     

Recovery characteristics of propofol anaesthesia, with and without nitrous oxide: a comparison with halothane/nitrous oxide anaesthesia in children

Few studies have examined whether nitrous oxide influences the recovery characteristics of propofol anaesthesia. The present study examined the effect of nitrous oxide on the recovery characteristics of propofol anaesthesia, and compared these data with those for halothane/nitrous oxide anaesthesia. Sixty children aged 3–12 years were assigned at random to receive one of three maintenance regimens: propofol with or without nitrous oxide (70%) or halothane/nitrous oxide (70%). During propofol/N₂O anaesthesia, the infusion rate of propofol (180±39 μg·kg⁻¹·min⁻¹) required to maintain the mean arterial pressure and heart rate within 20% of the baseline values was significantly less than that during propofol/O₂ (220±37 μg·kg⁻¹·min⁻¹; P <0.005). The time from discontinuation of anaesthesia to eye-opening (11±6 min), to response to commands (12±6 min), and to return of full wakefulness (21±10 min) after propofol/N₂O were similar to those after propofol/O₂, but significantly less (by approximately 30%) than those after halothane ( P <0.05). The overall incidence of emesis after propofol/N₂O (53%) was greater than that after propofol/O₂ (17%, P <0.05) and comparable to that after halothane/N₂O (58%). These data suggest that N₂O has little effect on the rate of recovery after propofol, but significantly increases the incidence of postoperative emesis, thereby attenuating one of the main attributes of propofol anaesthesia.     

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.     

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 · m^-2 iv; (C) propofol induction and maintenance; (D) as (C) plus lignocaine 2 mg · kg^-1 iv. All children received prophylactic atropine 0.02 mg · 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 thio-pentone-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 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.     

Anaesthesia with sevoflurane in children: nitrous oxide does not increase postoperative vomiting

BACKGROUND: Nitrous oxide (N2O) has been associated with postoperative nausea and vomiting (PONV), but some studies show conflicting data. The aim of this study was to assess whether the combination of N2O/sevoflurane, in paediatric general anaesthesia, increases the incidence of vomiting in the 24 h following surgery compared with sevoflurane alone. METHODS: One hundred and fourteen children, aged 1-10 years, who underwent testicle and inguinal hernia surgery, were randomized to receive one of the following two anaesthetic regimens: sevoflurane with 70% N2O (group A) or sevoflurane alone (group B). RESULTS: No significant differences were observed in the incidence of postoperative vomiting between the two groups. The overall incidence of postoperative vomiting was 14.9%; 14.3% in group A and 15.5% in group B (P=0.9). CONCLUSIONS: Nitrous oxide used in combination with sevoflurane is not associated with an increase in the incidence of emesis in children who undergo testicle and inguinal hernia procedures.     

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.     

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

Background: The oculocardiac reflex (OCR) is frequently observed duringstrabismus surgery. This study was designed to evaluate andcompare the effect of sevoflurane and desflurane on the incidenceof OCR. Methods: After obtaining Institutional Review Board approval and informedconsent from parents, we enrolled 237 paediatric patients, aged2–10 yr, undergoing strabismus surgery. No premedicationwas given. Anaesthesia was induced with thiopental and rocuronium.Patients were randomly allocated to one of the two anaestheticregimens. Group S (n = 123) received sevoflurane and Group D(n = 114) received desflurane, both with 60% N₂O/O₂ for maintenanceof anaesthesia. The OCR was defined as a 20% decrease in heartrate (HR) from baseline values obtained immediately before musclemanipulation. If the HR did not increase after release of muscletension, atropine 0.01 mg kg^–1 was administered. Results: There were no significant differences between the two groupsin age, sex, body weight, and the number of muscles operatedupon. The mean values of baseline HR were 123 (16) min^–1in Group S and 121 (18) in Group D (NS). The minimum HR was106 (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 inpaediatric patients.     

Does propofol reduce vomiting after strabismus surgery in children?

Background: Previous studies have indicated that propofol anaesthesia may reduce the incidence of postoperative nausea and vomiting after strabismus surgery in children. This study was designed to investigate the incidence of vomiting after strabismus surgery at two different levels of propofol anaesthesia compared to thiopental/isoflurane anaesthesia. Methods: Ninety ASA class I or II children, aged 5–14 yrs were randomly assigned to one of three groups: Group T/I (n=30) induction with 5 mg kg^-1 of thiopental and maintenance with isoflurane, group P5 (n=31) induction with propofol 2 mg kg^-1, maintenance with propofol infusion 5 mg kg^-1 h^-1 or group P10 (n=29) induction with propofol 2 mg kg^-1, maintenance with propofol 10 mg kg^-1 h^_I. All received glycopyrrolate, vecuronium, fentanyl and controlled ventilation with O₂/N₂O 30/ 70. Ketorolac i.v. was given to prevent postoperative pain. If additional analgesia was needed, ibuprofen/acetaminophen or buprenorphine was given according to clinical need. Results: There were no differences between study groups with respect to age, weight, history of previous anaesthesia or emesis after previous anaesthesia, duration of anaesthesia, surgery or sleep after anaesthesia, or number of muscles operated. The incidence of vomiting was 37%, 29% and 28% in groups T/I, P5 and P10, respectively. There were no statistically significant differences between the three groups in the incidence of vomiting. The median age of patients who vomited was 7.5 (range 5.0–13.7) yrs while the median age of the patients who did not vomit was 9.1 (range 5.0–14.0) yrs (P < 0.01). Conclusion: In the present study, propofol anaesthesia compared to thiopental/isoflurane anaesthesia did not reduce the incidence of vomiting following strabismus surgery in children.     

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.     

Oral clonidine premedication does not reduce postoperative vomiting in children undergoing strabismus surgery

BACKGROUND: We evaluated the effect of oral clonidine on postoperative vomiting (POV) in children undergoing strabismus surgery. METHODS: Eighty ASA physical status I children aged 3-12 years were randomly assigned to one of two groups in a double-blinded manner. One hour before surgery, each patient in the clonidine group (n=40) received clonidine 4 micro g kg-1 in apple juice 0.2 ml kg-1, and each of the controls (n=40) received apple juice 0.2 ml kg-1 only. The protocol for general anesthesia was propofol-sevoflurane in N2O/O2. A paracetamol suppository was administered in each case to prevent postoperative pain. Patient responses during 0-48 h after anesthesia were recorded as complete (no POV, no antiemetic rescue required), retching, vomiting, or rescue antiemetic. RESULTS: There were no significant differences between the clonidine and control groups regarding the number of patients with complete response (21 vs. 18, respectively) retching (10 vs. 14, respectively), vomiting (19 vs. 22, respectively), or rescue antiemetic (9 vs. 12, respectively) during the first 48 h. CONCLUSION: Oral premedication with clonidine 4 micro g kg-1 did not reduce the rate of POV in the children undergoing strabismus surgery.     

The efficacy of oral clonidine premedication in the prevention of postoperative vomiting in children following strabismus surgery

We evaluated the efficacy of clonidine given orally preoperatively for preventing postoperative vomiting (POV) in children undergoing propofol-nitrous oxide anaesthesia for strabismus surgery. Sixty children, ASA physical status I, aged 2-12 years, received diazepam, 0.4 mg x kg(-1) or clonidine, 4 microg x kg(-1) (n=30 each) orally, in a randomized double-blind manner. These drugs were given 105 min before an inhalational induction of anaesthesia. A complete response, defined as no POV and no need for rescue antiemetic medication, during 0-24 h after anaesthesia was 67% with diazepam and 93% with clonidine, respectively (P=0.024). No clinically adverse event was observed in any of the groups. In summary, pretreatment with oral clonidine enhances the antiemetic efficacy of propofol for the prevention of POV after paediatric strabismus surgery.     

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.     

Prevention of vomiting after strabismus surgery in children: dexamethasone alone versus dexamethasone plus low-dose ondansetron

BACKGROUND: Postoperative vomiting is a common complication after strabismus surgery. The combination of dexamethasone and ondansetron decreases vomiting after strabismus surgery, while dexamethasone alone decreases vomiting after tonsillectomy in children. We compared the effect of dexamethasone alone to ondansetron plus dexamethasone on postoperative vomiting among children undergoing strabismus surgery. METHODS: Healthy children, aged 2-14 years, who were undergoing strabismus surgery were entered into this randomized, blocked and stratified study. Patients were administered 0.5 mg.kg(-1) midazolam p.o., 20-30 min preoperatively when indicated. The patients had an intravenous induction with 2.5-3.5 mg.kg(-1) propofol or an inhalation induction of anaesthesia with halothane and N2O. All patients were given 20 microg.kg(-1) atropine i.v. Study drugs were administered in a double-blind fashion. Both groups received 150 microg.kg(-1) dexamethasone i.v. Group D patients received placebo and group OD received 50 microg.kg(-1) of ondansetron i.v. Anaesthesia was maintained with halothane and N2O. Postoperative fluid, vomiting and pain management were standardized. Patients were followed for 24 h. We studied 193 patients with 111 patients in the OD group. Demographic data were similar. RESULTS: The overall incidence of vomiting was 23%; in group D and 5%; in group OD (P < 0.001). Each episode of vomiting increased the in-hospital length of stay by 29 min (P < 0.001). CONCLUSIONS: There was a remarkably low incidence of postoperative vomiting of 5%; with the combination of dexamethasone plus a low-dose of ondansetron which more effectively decreased vomiting after strabismus surgery in children when compared with dexamethasone alone.     

Myopexy (Faden) results in more postoperative vomiting after strabismus surgery in children

BACKGROUND: Strabismus correction in children is associated with a high incidence of postoperative nausea and vomiting. The purpose of this prospective, double-blind study was to examine the influence of the surgical method for correction of squint on the incidence of postoperative vomiting. METHODS: One hundred and twenty consecutive children aged 2-12 years, scheduled for elective strabismus surgery, were enrolled in this prospective, double-blind study. A standardised total intravenous anaesthesia was given to all children. The development of perioperative oculocardiac reflex was noted and the number of episodes of vomiting during the first 48 h postoperatively was recorded. At the completion of the study, the children who were operated with myopexy according to Faden, were allocated to a Faden group, those without a myopexy to the non-Faden group. All the patients included in this study were operated on by the same surgeon with standardised techniques. RESULTS: The Faden group was younger, lighter and the operation time was longer (P<0.05). The incidence of vomiting was greater in the Faden group; 53% versus 12% (P<0.05). The incidence of oculocardiac reflex was similar in both groups; 40% in the Faden versus 28% in the non-Faden group, respectively. The total dose of propofol and alfentanil was similar between the groups. Requirement of analgesics for postoperative pain was similar in both groups. The only independent risk factor for postoperative vomiting was the Faden operation. CONCLUSION: The surgical method used for strabismus correction in children has a great influence on the incidence of postoperative vomiting. The Faden operation is associated with a very high incidence of postoperative vomiting; this particular group of patients has to be considered as a high risk group for postoperative vomiting and deserves an antiemetic prophylaxis.     

Peroperative treatment with i.v. ketoprofen reduces pain and vomiting in children after strabismus surgery

Background: Strabismus surgery is associated with both pain and vomiting. Ketoprofen is widely used in adults to treat acute pain, but there are only few reports of its use in children. This randomised, double-blind, placebo-controlled, parallel group study was designed to investigate the analgesic effect of i.v. ketoprofen and its effect on the incidence of vomiting in children after day-case strabismus surgery.
Methods: Fifty-nine ASA 1 children, aged 1–12 years, entered the study. After premedication with diazepam and glycopyrronium, anaesthesia was induced with fentanyl and propofol and maintained with isoflurane. After induction the children in the ketoprofen group received 1 mg kg⁻¹ ketoprofen followed by an infusion of 1 mg kg⁻¹ ketoprofen over 2 h. In the placebo group, children received 0.9% saline. The postoperative pain was assessed by the Maunuksela pain score (0=no pain, 10=worst possible pain). All children received fentanyl as a rescue analgesic if the Maunuksela score was ≥3.
Results: In the ketoprofen group the number of fentanyl doses was smaller compared to the placebo group (median 1, quartiles (0–2) vs. 2 (1–3), P =0.047). The children in the ketoprofen group had less pain at 30 min ( P =0.02) and the worst pain observed in the post anaesthesia care unit was lower (3 (0–6) vs. 5 (3–8), P =0.035). The incidence of vomiting was less in the ketoprofen group compared to the placebo group (17% vs. 41%, P =0.036). No serious adverse reactions occurred.
Conclusion: We concluded that ketoprofen administered i.v. during the operation produced analgesia and reduced opioid consumption and the incidence of vomiting in children after strabismus surgery.     

Dolasetron for the prevention of postoperative vomiting in children undergoing strabismus surgery

BACKGROUND: Children undergoing strabismus surgery have a high incidence of postoperative vomiting (POV). The purpose of this study was to assess the efficacy and safety of dolasetron for the prevention of emesis comparing a single 0.35 mg.kg-1 or 12.5 mg dose with placebo. METHODS: Children aged 2-12 years with an ASA status of 1 or 2 undergoing strabismus surgery were randomized in a double-blind manner to one of three treatment groups. Patients were excluded with a history of previous postoperative vomiting or motion sickness, allergy to serotonin receptor antagonists or previous antiemetic administration within 24 h prior to enrollment. General anaesthesia was induced with sevoflurane and N2O/O2 and maintained with isoflurane and N2O/O2. The study medication was administered 15 min prior to the end of surgery. Patients experiencing two or more episodes of vomiting were rescued in the postanaesthesia care unit (PACU) with metoclopramide 0.15 mg.kg-1. A total of 118 patients were enrolled with documentation of the number and severity of vomiting episodes, time to awakening, PACU length of stay and postoperative agitation. RESULTS: Patients with an acute complete response (ACR), defined as no emetic episodes and no rescue medication within 24 h of study drug administration were 62% (weight dose), 64% (fixed dose) and 33% (placebo, P < 0.05). CONCLUSIONS: There was no statistical difference between the 0.35 mg.kg-1 dose and the fixed 12.5 mg dose of dolasetron with both reducing the incidence of POV.     

Postoperative analgesia in children using preemptive retrobulbar block and local anesthetic infiltration in strabismus surgery

Background and Objectives. Postoperative pain management in pediatric strabismus patients is infrequently studied. Pediatric patients can be mobilized earlier if postoperative pain is minimized. In this study, two different regional anesthetic techniques, retrobulbar block and local infiltration, were compared with a “no block” control group for the postoperative management of pain in pediatric patients undergoing elective strabismus surgery. Methods. Thirty patients were randomly allocated to one of the study groups: group 1 (n = 10) control, group 2 (n = 10) retrobulbar block, and group 3 (n = 10) subconjunctival bupivacaine infiltration. The parameters that were evaluated during the early postoperative period (6 hours) were circulatory, pain scores by Visual Analog Scale (VAS) and Modified Pediatric Objective Pain Scale (MPOPS), additional analgesic requirement, nausea, and vomiting. The parameters that were evaluated after discharge from the hospital (on postoperative days 1 and 2) through questionnaires were additional analgesic requirement, nausea, vomiting, sleep disturbances, activity, and appetite. Results. Group 3 had significantly higher VAS and MPOPS scores at postoperative 120, 180, 240, 300, and 360 minutes than groups 1 and 2 (P < .05). Patients in group 2 seemed to have a higher incidence of nausea and vomiting both in the early (6 hours) and late postoperative (postoperative days 1 and 2) periods; however, the difference was not statistically significant. Group 2 required less analgesic compared with groups 1 and 3 during the late postoperative period. Late postoperative activity and appetite were better in groups 2 and 3. Conclusions. Because there was no significant difference in terms of postoperative analgesia in the retrobulbar block or subconjunctival local anesthetic infiltration groups compared with the control group, we suggest that conventional methods of pain treatment are adequate for postoperative analgesia in strabismus surgery.     

Nitrous oxide does not change the incidence of postoperative delirium or cognitive decline in elderly surgical patients

Background. Postoperative delirium and cognitive decline arecommon in elderly surgical patients after non-cardiac surgery.Despite this prevalence and clinical importance, no specificaetiological factor has been identified for postoperative deliriumand cognitive decline. In experimental setting in a rat model,nitrous oxide (N₂O) produces neurotoxic effect at high concentrationsand in an age-dependent manner. Whether this neurotoxic responsemay be observed clinically has not been previously determined.We hypothesized that in the elderly patients undergoing non-cardiacsurgery, exposure to N₂O resulted in an increased incidenceof postoperative delirium than would be expected for patientsnot receiving N₂O. Methods. Patients who were 65 yr of age, undergoing non-cardiacsurgery and requiring general anaesthesia were randomized toreceive an inhalational agent and either N₂O with oxygen oroxygen alone. A structured interview was conducted before operationand for the first two postoperative days to determine the presenceof delirium using the Confusion Assessment Method. Results. A total of 228 patients were studied with a mean (range)age of 73.9 (65–95) yr. After operation, 43.8% of patientsdeveloped delirium. By multivariate logistic regression, age[odds ratio (OR) 1.07; 95% confidence interval (CI) 1.02–1.26],dependence on performing one or more independent activitiesof daily living (OR 1.54; 95% CI 1.01–2.35), use of patient-controlledanalgesia for postoperative pain control (OR 3.75; 95% CI 1.27–11.01)and postoperative use of benzodiazepine (OR 2.29; 95% CI 1.21–4.36)were independently associated with an increased risk for postoperativedelirium. In contrast, the use of N₂O had no association withpostoperative delirium. Conclusions. Exposure to N₂O resulted in an equal incidenceof postoperative delirium when compared with no exposure toN₂O. ⁴Present address: Staff Statistician, University of Pittsburgh,PA 15213, USA     

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.