piperidines and Strabismus

Both over- and undercorrection can occur in up to 10-15% of strabismus surgeries. Use of adjustable suture technique and an intraoperative awake test may decrease the incidence of over- or undercorrection. In this study, we investigated the ability to provide optimal conditions for intraoperative awake strabismus suture adjustment in children by means of target-controlled infusions (TCI) of propofol and remifentanil propofol compared with propofol and sufentanil.. Forty-six ASA I-II patients undergoing strabismus surgery with intraoperative awakening were randomly assigned to anesthesia by TCI of propofol + sufentanil group (group SF) or propofol + remifentanil spontaneous breathing. Propofol was discontinued, and concentrations of the opioid TCIs were reduced to enable awake assessment of the mobility and position of the eye. Changes in intraocular pressure, respiratory function, hemodynamics, awakening time, and awaking quality were compared between the two groups. The degrees of sedation and analgesia were evaluated through the assessment of alertness and sedation scores (OAA/S) and visual analog scale scores (VAS).. There was no significant difference in intraocular pressure at three sampling points between two groups (P > 0.05). The heart rate (HR) and mean arterial blood pressure (MAP) in group SF were significantly lower than group RF during laryngeal mask insertion (P < 0.05) as well as during the wake-up test (P < 0.05). Spontaneous breathing was maintained in all patients, and there was no significant difference in RR and Sp02 at T1-T11 between the groups (P > 0.05). There was no significant difference in the target effect-site concentration of propofol at T1-T10 between the groups (P > 0.05). The wake-up times in group SF were significantly longer than in group RF (P < 0.05). In contrast, the quality of wake-up test and the degree of consciousness after the patients were awakened were significantly better (19 good and 4 satisfactory vs 15 good, 2 satisfactory, and 6 poor) in SF group than RF group. The VAS was significantly lower at T6-T9 in SF group than in RF group (P < 0.05). The incidence of untoward events during and after surgery, such as respiratory depression and apnea, oculocardiac reflex, coughing, groan and nausea, and vomiting was not significantly different between the groups (P > 0.05).. Propofol combined with sufentanil or remifentanil can be suitable for planned intraoperative awakening for an adjustable suture technique in pediatric patients during strabismus surgery. Remifentanil has quicker wake-up time; however, sufentanil demonstrated an advantage in terms of better analgesia, more stable hemodynamics, and improved qualify of awakening.

Topics: Anesthesia, Intravenous; Anesthetics, Intravenous; Balanced Anesthesia; Blood Pressure; Child; Double-Blind Method; Female; Heart Rate; Humans; Intraocular Pressure; Male; Monitoring, Intraoperative; Ophthalmologic Surgical Procedures; Pain Measurement; Piperidines; Propofol; Prospective Studies; Remifentanil; Sleep; Strabismus; Sufentanil; Wakefulness

Sevoflurane is widely used for paediatric anaesthesia. However, many cases of emergence agitation after sevoflurane anaesthesia have been reported and pain was suggested as a major contributing factor. The purpose of this study was to evaluate the effect of sub-Tenon lidocaine injection on emergence agitation in children receiving sevoflurane or propofol-remifentanil anaesthesia.. We enrolled 260 children, aged 4-10 years, who were scheduled for strabismus surgery, and randomized them to one of four groups: group SS, SL, BS, and BL. Anaesthesia was maintained with sevoflurane (SS, SL) or propofol-remifentanil infusion (BS, BL). At the end of surgery, the surgeon injected into the sub-Tenon space 1 ml of isotonic saline (SS, BS) or 2% lidocaine (SL, BL). Emergence behaviour was assessed in the post-anaesthesia care unit using a 5-point scoring scale (score 1, asleep; 2, awake and calm; 3, irritable or consolable crying; 4, inconsolable crying; and 5, severe restlessness). We defined a score of 4 or 5 as emergence agitation. The incidence of emergence agitation was analysed using χ² and Fisher's exact test.. The incidence of emergence agitation in group SL and BL was significantly lower compared to group SS and BS, respectively (P = 0.011, 0.019). The lidocaine-injected group showed significantly lower occurrence of emergence agitation (10.4%) than isotonic saline-injected group (27.2%; P = 0.001). Emergence agitation was significantly higher following sevoflurane (25.0%) than balanced anaesthesia (13.1%; P = 0.023).. The frequency of emergence agitation is significantly reduced by sub-Tenon lidocaine injection regardless of the modality of anaesthesia used.

Topics: Anesthesia Recovery Period; Anesthesia, General; Anesthetics, Combined; Anesthetics, Inhalation; Anesthetics, Intravenous; Anesthetics, Local; Child; Child, Preschool; Female; Follow-Up Studies; Humans; Incidence; Lidocaine; Male; Methyl Ethers; Ophthalmologic Surgical Procedures; Pain, Postoperative; Piperidines; Propofol; Psychomotor Agitation; Remifentanil; Sevoflurane; Strabismus

In this prospective, randomized, double-blind study, we evaluated and compared the incidence of postoperative nausea and vomiting (PONV) after paediatric strabismus surgery with two different anaesthetic methods, sevoflurane or remifentanil-sevoflurane.. In total, 78 paediatric patients (aged 6-11 yr) undergoing strabismus surgery were enrolled and randomly assigned to two groups, sevoflurane (Group S) and remifentanil-sevoflurane (Group R). Anaesthesia was maintained with 2-3% sevoflurane in Group S (n=39) or with a continuous infusion of remifentanil combined with 1% sevoflurane in Group R (n=39), both using 50% N(2)O/O(2). Arterial pressure and heart rate before induction, after tracheal intubation, after skin incision, and at the end of surgery were recorded. The incidence of PONV in the post-anaesthesia care unit, the day surgery care unit, and at home 24 h after surgery was recorded.. Arterial pressure and heart rate were stable throughout the surgery, but were significantly lower in Group R than in Group S after tracheal intubation and skin incision. The incidence of PONV and postoperative vomiting was 17.9%/17.9% and 12.8%/10.2% (Group S/Group R) at the respective time points; values were comparable between the groups.. The incidence of PONV after paediatric strabismus surgery under sevoflurane anaesthesia was relatively low, and combining remifentanil with sevoflurane did not further increase the incidence.

Topics: Anesthetics, Combined; Anesthetics, Inhalation; Anesthetics, Intravenous; Blood Pressure; Child; Double-Blind Method; Female; Heart Rate; Humans; Male; Methyl Ethers; Piperidines; Postoperative Nausea and Vomiting; Remifentanil; Sevoflurane; Strabismus

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.. 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.. 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.. Remifentanil enhanced the degree of bradycardia due to OCR as compared with sevoflurane during paediatric strabismus surgery.

Topics: Anesthesia; Blood Pressure; Child; Child, Preschool; Female; Heart Rate; Humans; Infant; Male; Midazolam; Nausea; Piperidines; Reflex, Oculocardiac; Remifentanil; Strabismus; Vomiting

The composite auditory evoked potential index (cAAI), derived from the AEP Monitor/2 (version 1.6; Danmeter A/S, Odense, Denmark) is a measure of the hypnotic component of general anaesthesia. The purpose of this study was to evaluate the impact of cAAI guidance on propofol consumption and emergence times in children receiving total intravenous anaesthesia (TIVA) with propofol and remifentanil.. Twenty children, aged 3-11 years, scheduled for strabismus repair under TIVA with propofol and remifentanil were enrolled. Remifentanil was given to all patients at a constant infusion rate of 0.3 microg kg(-1) min(-1) throughout the anaesthesia. Patients were randomly allocated to receive a continuous propofol infusion adjusted either according to a conventional clinical practice (Group C, n = 10) or guided by cAAI-monitoring (Group G, n = 10, target cAAI 25-35). All patients were connected to the AEP Monitor/2, but in group C the anaesthetist was blinded to cAAI values. Propofol consumption (mgkg(-1)h(-1)) and emergence times (min) were the primary and secondary outcome measures.. Propofol consumption and emergence times (mean +/- SD) were significantly lower in group G compared to group C (Propofol: G: 4.2 +/- 1.7 vs. C 6.4 +/- 1.3 mg kg(-1) h(-1); P < 0.01; emergence times: G: 5.1 +/- 3.7 vs. C 13.2 +/- 8.2 min; P < 0.01). Intraoperative cAAI values (median [interquartile range]) were significantly higher in group G (23.9 [18-29.7]) than in group C (18.4 [16.0-22.1]; P < 0.01). Haemodynamic variables remained stable within age-related limits, and there were no observations of adverse events, especially no clinical signs of intraoperative awareness in any patient.. Composite auditory evoked potential index monitoring during propofol/remifentanil-TIVA in children results in reduced propofol consumption and faster emergence.

Topics: Analysis of Variance; Anesthesia Recovery Period; Anesthesia, Intravenous; Anesthetics, Combined; Anesthetics, Intravenous; Child; Child, Preschool; Electroencephalography; Evoked Potentials, Auditory; Hemodynamics; Humans; Monitoring, Intraoperative; Piperidines; Propofol; Remifentanil; Strabismus; Time Factors; Treatment Outcome

BACKGROUND AND STUDY GOALS: Strabismus surgery in children is frequently associated with a very high incidence of postoperative nausea and vomiting (PONV). In this study we investigated, whether TIVA is superior to inhalation anaesthesia concerning PONV when a prophylaxis using dimenhydrinate (diphenhydramine chlorotheophyllate) is administered in both groups.. 110 patients (3-10 years) were prospectively and randomly allocated to one of the following groups: Group TD (TIVA/dimenhydrinate; n= 55): anaesthesia was induced and maintained using remifentanil and propofol in common clinical dosages. Patients were ventilated with 30% O(2) in air. Group VD (Volatile/ dimenhydrinate; n= 55): anaesthesia was induced and maintained with sevoflurane in common clinical concentrations together with N(2)O in 30% O(2). All patients received dimenhydrinate 1 mg.kg(-1) i.v. after induction. PONV was recorded within the first 24 h postoperatively. The chi-square test and a multivariate analysis were used for statistical analysis.. 52 patients of group TD and 54 of group VD were analysed. There was a trend in the incidence of postoperative nausea (PN): group TD 17%, 95% CI: 8-30%) compared to group VD 31%, 95% CI: 20-46%), p = 0.09. No difference was seen for PV and PONV: 21% (95% CI: 11-35%) in group TD vs. 35% (95% CI: 23-49%) in group VD, p = 0.109. These non-significant results can be easily attributed to the lack of power about 30%) of this study. According to the results of the multivariate analysis volatile anaesthesia was identified as an independent risk factor for PONV (OR: 2.92, 95% CI: 1.02-8.36). Other variables that were found to be an independent risk factor included history of PONV (OR: 8.19, 95% CI: 1.84-36.43), surgery lasting longer than 30 min (OR: 5.89, 95% CI: 1.82-19.82) and "Faden-operations" (retroequatorial myopexy) (OR: 5.48, 95% CI: 1.74-17.21).. TD only showed a trend to lower PN incidences and no differences as for PV and PONV incidences, most likely due to a lack of power of this study. However, according to the results of the multivariate analysis, inhalation anaesthesia was shown to be an independent risk factor for PONV, as were history of PONV, surgery >30 min and "Faden-operations".

Topics: Anesthesia, Inhalation; Anesthesia, Intravenous; Anesthetics, Inhalation; Anesthetics, Intravenous; Antiemetics; Child; Child, Preschool; Dimenhydrinate; Female; Humans; Male; Methyl Ethers; Nitrous Oxide; Ophthalmologic Surgical Procedures; Pain, Postoperative; Piperidines; Postoperative Nausea and Vomiting; Propofol; Remifentanil; Risk Factors; Sevoflurane; Strabismus

Postoperative vomiting (POV) after strabismus surgery in children results in discomfort and prolonged hospital stays. Opioids increase the incidence of POV. Remifentanil has a context-sensitive half-life of 3 to 4 min, and how this short half-life influences POV in those patients is unknown. We conducted a prospective, double-blinded study in 81 ASA status I or II children from 2 to 12 yr of age undergoing elective strabismus surgery under general anesthesia. Patients were randomized to receive either remifentanil (bolus 1 microg/kg; infusion 0.1-0.2 microg x kg(-1) x min(-1)) or fentanyl (2 microg/kg, and 1 microg/kg every 45 min). POV episodes were recorded for 25 h. Pain scores were obtained by using an objective pain scale for 60 min during recovery. The number of patients who experienced POV did not differ significantly between groups (49% vs 48%). However, in the Remifentanil group, POV episodes were significantly less frequent (0.95 vs 2.2 episodes). In contrast, fentanyl was associated with lower pain scores during the first 30 min of recovery. We conclude that children undergoing strabismus surgery under balanced anesthesia with remifentanil, compared with fentanyl, showed less frequent POV. However, early postoperative analgesia was better with fentanyl.. Opioids increase the incidence of postoperative vomiting (POV). Remifentanil is characterized by the shortest half-life of all opioids used in anesthetic practice. Therefore, we studied the effect of remifentanil on POV compared with the longer-acting opioid fentanyl in children undergoing strabismus surgery.

Topics: Analgesics, Opioid; Child; Child, Preschool; Double-Blind Method; Female; Fentanyl; Humans; Incidence; Male; Pain, Postoperative; Piperidines; Postoperative Complications; Prospective Studies; Remifentanil; Strabismus; Vomiting

Postoperative nausea and vomiting (PONV) is still one of the major problems in strabismus surgery, especially in children. In recent years many studies have been published, suggesting that choosing propofol as the anaesthetic agent may help to reduce the high incidence of PONV in children undergoing strabismus surgery. Experience with remifentanil in children is still very limited and little is known, whether propofol in combination with this new short acting opioid is also superior regarding PONV in squint surgery compared to sevoflurane/N2O. Additionally, little is known, whether the type of operation or the muscle which is operated on has any influence with respect to PONV.. Following sample size estimation, ethics committee approval and parents informed consent in a prospective, randomised, observer-blind study 105 ASA I and II children aged 3-8 years scheduled for elective strabismus surgery were assigned into one of the following groups: Group TIVA (propofol/remifentanil, n = 53): anaesthesia was induced by remifentanil 0.5 microgram kg-1 min-1 over 2 min (loading phase), followed by 3 mg kg-1 propofol along with 30% O2 in air. After endotracheal intubation anaesthesia was maintained initially with remifentanil 0.25 microgram kg-1 min-1 and propofol 10 mg kg-1 h-1 by constant infusion. In the course of the operation the infusions of the anaesthetics were adjusted to the decreasing need for anaesthesia. Group VOLATIL (sevoflurane/N2O, n = 52): anaesthesia was induced by inhalation of sevoflurane along with 50% O2 in N2O. After endotracheal intubation anaesthesia was maintained with sevoflurane 1.0-1.5 MAC along with 30% O2 in N2O and in the course of the operation the administration of the inhaled anaesthetics was adjusted correspondingly. Preoperatively collected data included gender, age, weight and history of PONV. Intraoperatively collected data consisted of data belonging to routine monitoring (heart rate, blood pressure, peripheral oxygen saturation and temperature) as well as the duration of the operation and anaesthesia and specific data regarding the operation (including the number and type of muscles as well as the kind of operation). Data collected within the first 24 hours postoperatively in the recovery room and on the ward by blinded observers included any PONV events as well as the antiemetics and analgesics applied.. Vomiting was observed less frequently in the TIVA-group than in the VOLATIL-group (21 of 53 vs. 32 of 52, p = 0.03) within the first 24 hours postoperatively. Posterior fixation suture ("faden-operation") compared to other operations was followed rather frequently by nausea and vomiting (30 of 44 and 33 of 44, respectively), whereas recessions were rarely associated with nausea and vomiting (12 of 35 and 9 of 35, respectively).. TIVA with propofol/remifentanil proved to be a suitable form of anaesthesia for children in this setting. Propofol showed advantages over sevoflurane/N2O with respect to PONV after squint surgery in children also when applied in the combination with remifentanil. TIVA with propofol/remifentanil may therefore be one way to reduce the high incidence of PONV in this setting, bearing in mind, that PONV is not only influenced by the regimen of the general anaesthesia but rather by the combination of many other factors, in particular the type of operation.

Topics: Anesthesia, Inhalation; Anesthesia, Intravenous; Child; Child, Preschool; Female; Humans; Male; Methyl Ethers; Nitrous Oxide; Piperidines; Postoperative Nausea and Vomiting; Propofol; Prospective Studies; Remifentanil; Sevoflurane; Single-Blind Method; Strabismus

Remifentanil hydrochloride is a new, ultrashort-acting opioid metabolized by nonspecific plasma and tissue esterases. We conducted this multicenter study to examine the hemodynamic response and recovery profile of premedicated children undergoing strabismus repair who were randomly assigned to receive one of four treatment drugs (remifentanil, alfentanil, isoflurane, or propofol) along with nitrous oxide and oxygen for maintenance of anesthesia. Induction of anesthesia was by nitrous oxide, oxygen, and halothane or nitrous oxide, oxygen, and propofol. Anesthesia was then maintained with remifentanil 1.0 microgram/kg over 30-60 s, followed by a constant infusion of 1.0 microgram.kg-1.min-1, alfentanil 100 micrograms/kg bolus followed by a constant infusion of 2.5 micrograms.kg-1.min-1, propofol 2.5 mg/kg bolus followed by a constant infusion of 200 micrograms.kg-1.min-1, or isoflurane 1.0 minimum alveolar anesthetic concentration. The infusions of the anesthetics and the administration of the inhaled gases were adjusted clinically by predetermined protocols. Elapsed time intervals from the end of surgery to the time the patients were tracheally extubated and displayed purposeful movement, as well as the time the patients met the postanesthesia care unit (PACU) and hospital discharge times, were recorded. Heart rate and systolic and diastolic blood pressure were measured at fixed intervals. In addition, cardiovascular side effects (bradycardia, hypotension, and hypertension) as well as vomiting, pruritus, agitation, and postoperative hypoxemia were also noted. There were no significant differences in patient demographics among the treatment groups. There was no difference in the early recovery variables (times to extubation and purposeful movement) or the times to PACU and hospital discharge among groups. There were significant differences in side effects among the groups. Patients who received remifentanil had higher PACU objective pain-discomfort scores than those who received alfentanil and propofol. Patients anesthetized with alfentanil had a greater incidence in the use of naloxone and a greater incidence of postoperative hypoxemia compared with those anesthetized with remifentanil. The incidence of postoperative hypoxemia was the same for remifentanil, propofol, and isoflurane groups. There were no significant differences in the incidence of emesis among the four groups, and all four groups had similar hemodynamic profiles. We conclude that remifentan

Topics: Alfentanil; Ambulatory Surgical Procedures; Analgesics, Opioid; Anesthesia; Anesthesia Recovery Period; Anesthetics, Inhalation; Anesthetics, Intravenous; Child; Child, Preschool; Elective Surgical Procedures; Female; Hemodynamics; Humans; Isoflurane; Male; Pain, Postoperative; Piperidines; Propofol; Remifentanil; Strabismus

To analyze the effectiveness and usefulness of contact topical anesthesia in strabismus surgery in adult patients.. A prospective study was conducted on 20 patients undergoing strabismus surgery using contact topical anesthesia and sedation with remifentanil. The intensity of pain was recorded using a numeric pain rating scale at the time of anesthesia implementation, during the surgical procedure, 30 min afterwards, and during the first postoperative day. The incidence of oculocardiac reflex, postoperative nausea and vomiting, corneal ulcers, patient satisfaction (numerically from 0 to 10) and the degree of residual ocular deviation were also assessed.. The operation was performed successfully in all patients. Average pain intensity was 1.40 ± 1.73 during anesthesia implementation, 4.20 ± 2.57 during the surgical procedure, 2.50 ± 2.54 30 min after surgery, and 3.55 ± 2.89 during the first postoperative day. Oculocardiac reflex was observed in 7 patients (35%), postoperative nausea and vomiting in 4 (20%), and corneal ulcer in 4 (20%). The patient satisfaction was 9.53 ± 2.51. More than two-thirds (70%) of patients had a residual ocular deviation less than 10 prism diopters.. Contact topical anesthesia is a safe and effective alternative for strabismus surgery in adult patients. Contact topical anesthesia provides adequate pain control, lower incidence of postoperative nausea and vomiting and oculocardiac reflex, and optimal setting of ocular alignment.

Topics: Administration, Ophthalmic; Adult; Aged; Aged, 80 and over; Anesthesia, Local; Anesthetics, Local; Bupivacaine; Conscious Sedation; Corneal Ulcer; Female; Humans; Hypnotics and Sedatives; Lidocaine; Male; Middle Aged; Pain Measurement; Pain, Postoperative; Patient Satisfaction; Piperidines; Postoperative Nausea and Vomiting; Prospective Studies; Reflex, Oculocardiac; Remifentanil; Strabismus; Treatment Outcome; Young Adult

Angelman syndrome is a hereditary disease described by Angelman. The clinical features of Angelman syndrome are characterized by mental retardation, puppet-like ataxia, easily excitable personality, seizures, paroxysmal laughter, strabismus and macroglossia. A 4-year-old girl with Angelman syndrome underwent strabismus repair under general anesthesia. Anesthesia was slowly induced with sevoflurane in oxygen and maintained with air, oxygen, propofol and remifentanil. Tracheal intubation was performed after administration of rocuronium. During and after anesthesia, no adverse events regarding circulatory and respiratory systems occurred. However, this case demonstrates that it is necessary to pay attention to airway troubles including the difficulty of tracheal intubation, management of body temperature and chronotropic action or respiratory depression by anesthetic agents.

Topics: Anesthesia, General; Angelman Syndrome; Child, Preschool; Female; Humans; Intraoperative Care; Intubation, Intratracheal; Methyl Ethers; Monitoring, Intraoperative; Piperidines; Propofol; Remifentanil; Sevoflurane; Strabismus

To determine the outcome of immediate suture adjustment in adjustable suture strabismus surgery using a general anaesthetic technique.. Adjustable suture strabismus surgery was performed in 69 patients using a target-controlled infusion of propofol-remifentanil. Sutures were adjusted immediately following surgery and patient satisfaction and ocular alignment were assessed at 3 months postoperatively.. Preoperatively, 71% (49/69) of patients were divergent (group 1) and 29% (20/69) were convergent (group 2). Following surgery, the mean deviation in group 1 was 3.5 +/- 13.08 Delta exodeviation for near and 0.8 +/- 10.66 Delta exodeviation for distance. The mean postoperative deviation in group 2 was 2.6 +/- 9.1 Delta esodeviation for near and 2 +/- 9.0 Delta esodeviation for distance. Overall, 80% (45/69) were within 10 Delta of orthotropia.. Single-stage adjustable suture strabismus surgery produces good results and is well suited to day case surgery.

Topics: Adolescent; Adult; Aged; Ambulatory Surgical Procedures; Anesthesia; Anesthetics, Intravenous; Humans; Middle Aged; Patient Satisfaction; Piperidines; Postoperative Complications; Postoperative Period; Propofol; Remifentanil; Retrospective Studies; Strabismus; Suture Techniques; Young Adult

Topics: Child; Heart Rate; Humans; Ketamine; Piperidines; Reflex, Oculocardiac; Remifentanil; Strabismus

Maintaining spontaneous ventilation in children, using total intravenous anesthesia (TIVA), is often desirable, particularly for airway endoscopy. The aim of this study was to evaluate the effect of age on the dose of remifentanil tolerated during spontaneous ventilation under anesthesia maintained with infusions of propofol and remifentanil and to provide guidelines for the administration of remifentanil and propofol to maintain spontaneous ventilation in children.. Forty-five children scheduled for strabismus surgery were divided by age into three groups (group I: 6 months-3 years, group II: 3 years-6 years, and group III: 6 years-9 years). The propofol infusion was titrated using State Entropy as a pharmacodynamic endpoint and remifentanil infused, using a modified up-and-down method, with respiratory rate depression as a pharmacodynamic endpoint. A respiratory rate of just greater than 10, stable for 10 min, determined the final remifentanil infusion rate. The group mean was estimated from the final remifentanil infusion rate tolerated (RD(50)).. The RD(50) of groups I, II, and III were 0.192 (0.08), 0.095 (0.04), and 0.075 (0.03) microg x kg(-1) x min(-1) respectively. Pair-wise comparisons between the groups for the rate of remifentanil tolerated revealed a statistically significant increase in the RD(50) in children less than 3 years of age compared with older children in groups II and III (P < 0.001). The relationship between remifentanil dose and age, weight or height was not linear.. Younger children, especially those aged less than 3 years, tolerate a higher dose of remifentanil while still maintaining spontaneous respiration. TIVA with spontaneous ventilation is readily achieved in younger children and infants.

Topics: Age Factors; Anesthesia, Intravenous; Anesthetics, Intravenous; Body Height; Body Weight; Child; Child, Preschool; Female; Humans; Infant; Linear Models; Male; Monitoring, Intraoperative; Piperidines; Propofol; Prospective Studies; Remifentanil; Respiration; Strabismus