Mivacurium infusion requirement and spontaneous recovery of neuromuscular transmission in children anaesthetized with nitrous oxide and fentanyl,halothane, isoflurane or sevoflurane

BACKGROUND: Forty children, aged 3-11 years, ASA I or II, were allocated at random to receive N2O/O2-fentanyl or 1 MAC halothane, isoflurane or sevoflurane-N2O/O2 anaesthesia. Mivacurium was used for muscle relaxation. METHODS: Electromyographic response of the adductor pollicis to train-of-four (TOF) stimulation, 2 Hz for 2 s, applied to the ulnar nerve at 10-s intervals was recorded using the Relaxograph (Datex, Helsinki, Finland). An intubating dose of mivacurium, 0.2 mg.kg-1 was given, and when T1 returned to 5%, muscle relaxation was maintained by continuous infusion of mivacurium, adjusted manually to maintain a stable 90-99% block. RESULTS: Halothane, isoflurane and sevoflurane groups had lower infusion requirements for mivacurium than the N2O-fentanyl group (P=0.000083). Mivacurium requirement was 18.8 +/- 6.8, 10.8 +/- 4.2, 6.9 +/- 3.9 and 9.6 +/- 5.6 microg.kg-1.min-1 for children receiving N2O/O2-fentanyl, halothane, isoflurane and sevoflurane anaesthesia, respectively. CONCLUSIONS: Spontaneous recovery from T1=10% to TOF ratio=0.7 was insignificantly prolonged from 6.3 to 12.5 min in the fentanyl group to 7-16.5 min in children anaesthetized with inhalational anaesthetics.     

Induction and recovery characteristics of desflurane and halothane anaesthesia in paediatric outpatients *

This study compares induction and recovery characteristics of desflurane and halothane in children undergoing elective outpatient surgery (hernia repair, circumcision and orchidopexy). Fifty-six patients one month to 12 years of age were randomly assigned to one of three study groups. In addition to nitrous oxide, group I received desflurane (D) for induction and maintenance; group II received halothane (H) for induction and desflurane for maintenance; and group III received halothane for induction and maintenance. All patients received caudal blocks at the end of surgery. There was no significant difference in induction time (mean ± SD) among the three groups (1.7 ± 0.5, 1.7 ± 0.5 and 1.0 ± 0.5 min for groups I, II and III respectively). Airway complications (coughing, breath holding, and laryngospasm) were significantly higher among the children induced with desflurane than among either of the halothane induction groups. Premedication had no effect on reducing the number of airway complications. Emergence and recovery times (mean ± SD) were significantly shorter among both desflurane maintenance groups (3.6 ± 1.7 and 11 ± 8 min) than among the group maintained on halothane (7.9 ± 3.5 and 29.9 ± 10.6 min respectively). A brief halothane induction did not compromise the fast recovery characteristics of desflurane. There was no difference among the groups in time to discharge home (approx. 3 h). This study confirms the value of desflurane as a maintenance agent in paediatric anaesthesia. In our patients, a brief halothane induction did not compromise the fast recovery characteristics of desflurane.     

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.     

Postoperative oxygen saturation following propofol–nitrous oxide versus halothane–nitrous oxide anaesthesia in children

Postoperative haemoglobin oxygen saturation values ( S po₂) may be decreased after even minor surgical procedures. Therefore, we evaluated the incidence of postoperative hypoxaemia in children randomized to receive either halothane–nitrous oxide (N₂O) or propofol–N₂O, during a standardized anaesthetic technique for superficial surgery. After tracheal extubation, all patients received 100% oxygen for at least 3 min and then were transported to the Postanaesthetic Care Unit (PACU) in the left lateral position. The S po₂ values were monitored in the PACU and supplemental oxygen was administered to all patients with S po₂ < 90%. There were no significant differences in demographic characteristics or in the times to tracheal extubation and transport to the PACU between the two groups. While S po₂ values decreased in both groups during transport, they did not differ significantly at any time in the PACU. In addition, no significant differences in S po₂ values were noted at any point between subgroups of patients who did or did not undergo surgical procedures associated with postoperative pharyngeal bleeding. We conclude that the use of propofol does not decrease the incidence of postoperative hypoxaemia in this patient population.     

Drive and timing components of respiration in young children following induction of anaesthesia with halo-thane or ketamine

Timing and drive components of respiration were studied in 18 young children following induction of anaesthesia with ketamine and were compared with results from ten children following induction of anaesthesia with halothane. During one minute of quiet breathing, signals from a pneumotachograph attached to the anaesthetic mask were analysed for tidal volume (Vt), respiratory frequency (f), minute volume (Ve), inspiratory and expiratory times (Ti, Te) and flow pattern. Following induction of anaesthesia with ketamine, children breathed more slowly and deeply than children receiving halothane, but there was no significant difference in Ve or in Vt/Ti, suggesting that respiratory drive was similar in the two groups of children. In the children receiving ketamine, Ti was more than twice as long, and thus the ratio Ti/Te was significantly increased, in comparison with the group receiving halothane. In addition to the prolonged Ti in the children induced with ketamine, there was a more rapid increase in volume in early inspiration than in late inspiration, which is an apneustic breathing pattern. There was a slower decrease in volume in early expiration, with occasional early expiratory breath holding lasting up to three seconds, in the ketamine-induced children. The unique breathing pattern demonstrated with ketamine, consisting of large Vt, increased Ti/Te ratio, apneustic inspiratory pattern, and expiratory braking, contributed to an increased mean lung volume above functional residual capacity, of 2.40 ml.kg-1 body weight, in comparison to 1.27 ml.kg-1 in the children receiving halothane.     

Anaesthesia for short outpatient procedures. A comparison between thiopentone and propofol in combination with fentanyl or alfentanil

We studied supplementation of propofol or thiopentone anaesthesia with 0.5 or 1.0 mg alfentanil or 0.05 or 0.1 mg fentanyl for minor gynaecological outpatient procedures. Four hundred patients scheduled for elective termination of pregnancy were randomly allocated to one of eight groups. Induction agent doses, peroperative complications, complaints about pain and emesis during the postoperative period, and time to discharge were studied. Propofol compared to thiopentone was associated with a shorter time to discharge, 103±28 and 115±33 minutes respectively ( P <0.05) and anxiety during recovery was more frequent in the thiopentone group ( P <0.05). The need for postoperative reserve analgesics was less in the alfentanil group ( P <0.05). We found, however, no major differences between the supplementations tested regarding the total dose of induction agent, emesis or time to discharge. Supplementation with 1.0 mg of alfentanil to propofol was found to be the best combination tested for short outpatient procedures.     

Neuromuscular effects of 600 μg·kg−1 of rocuronium in infants during nitrous oxide-halothane anaesthesia

Rocuronium bromide (Zemuron) is a new steroidal nondepolarizing neuromuscular blocking drug. We were interested in determining the effect of a bolus of rocuronium in infants during halothane anaesthesia as we did previously in older children. Eighteen infants (2-11 months) received a bolus of 600 μg·kg^?1, which is equal to twice the dose of rocuronium estimated to produce 95% depression of neuromuscular function (ED₉₅) in children (2-12 yr). Neuromuscular blockade was monitored by recording the electromyographic activity of the adductor pollicis muscle resulting from supramaximal stimulation of the ulnar nerve at 2 Hz for 2 s at 10-s intervals. Time (mean ± SEM, range) from administration of 600 μg·kg^?1 rocuronium to 90% (B₉₀) and 100% (B₁₀₀) neuromuscular block was 37 ± 2 (20-60) s and 64 ± 10 (20-180) s, respectively. The time to recovery of neuromuscular transmission to 10% (T₁₀) was 35.3 ± 3.0 (20.7-57.8) min and to 25% of baseline (T₂₅) was 41.9 ± 3.2 (24.3-67.7) min. The recovery index (T₂₅-T₇₅) was 26.6 ± 2.7 (11.7-44.5) min, and the time to recovery of the train-of-four ratio (T₄/T₁) ± 0.75 was 82.1 ± 6.9 (53.2-138.3) min. The plasma concentration of rocuronium when T₁ had recovered to about 30% was 654 ± 34 (417-852) ng·ml^?1 which is similar to that observed in children. Six-hundred μg·kg^?1 of rocuronium has a rapid onset of effect in infants and prolonged duration of action in infants compared to children.     

Perioperative complement activation in neonates under halothane or fentanyl anaesthesia

We investigated perioperative changes in complement activation in 18 neonates undergoing elective abdominal surgery with or without thoracotomy by measuring plasma concentrations of C3a and C5a, and leucocyte counts in peripheral blood. The 18 neonates, ranging in age from 1 to 17 days, were randomly divided into two groups according to type of anaesthetic procedures; the "halothane group" consisted of nine neonates in whom general anaesthesia was maintained with halothane and nitrous oxide (N2O) in oxygen, while the "fentanyl group" consisted of nine neonates in whom general anaesthesia was maintained with fentanyl and N2O in oxygen. Plasma C3a and C5a concentrations were higher in the fentanyl group than in the halothane group during the perioperative period. We have demonstrated that abdominal surgical trauma caused complement activation even in neonates undergoing the fentanyl rather than the halothane anaesthesia. Further studies are required to elucidate the precise mechanisms and the clinical implication of perioperative complement activation in neonates.     

A comparison of remifentanil and fentanyl for fast track paediatric cardiac anaesthesia

BACKGROUND: Fast track anaesthetic protocols for cardiac surgical patients have been developed to facilitate early tracheal extubation. We compared anaesthetics based on either remifentanil or fentanyl for fast track paediatric cardiac anaesthesia. METHODS: Fifty patients with atrial septal defect or simple ventricular septal defect who were deemed suitable for fast track anaesthetic management were randomly assigned to group R (remifentanil) or group F (fentanyl). After sevoflurane induction, patients received either R infusion or F bolus. Following intubation, isoflurane 0.5 MAC was administered to all patients. Blood pressure (BP) and heart rate (HR) were recorded at baseline and pre- and postinduction, intubation, skin incision and sternotomy. Other parameters measured included time to extubation, reintubation rate and requirements for postoperative analgesia, ondansetron, and nitroprusside in the paediatric intensive care unit. RESULTS: BP decreased similarly from baseline in both groups. Decreases in HR over time were significantly greater in group R. Haemodynamic response to incision/sternotomy was low and similar in both groups. There were no significant differences in extubation time, reintubation incidence, postoperative narcotic requirements, postoperative hypertension or postoperative nausea/vomiting. CONCLUSIONS: The remifentanil based anaesthetic was associated with a significantly slower HR than the fentanyl based anaesthetic. The clinical implications of the slower HR during remifentanil anaesthesia could be important and should be investigated.     

Evaluation of postural stability by computerised posturography following outpatient paediatric anaesthesia. Comparison of propofol/alfentanil/ N2O anaesthesia with thiopentone/halothane/N2O anaesthesia

Simple clinical tests, like Romberg's test or a walking test, have proved to be inadequate guidelines for safe discharge after outpatient anaesthesia (1, 2). A randomised study was therefore planned to compare postural stability measured by computerised posturography in 31 oral midazolam-atropine premedicated children aged 6.9 (s.e. 0.4) years who had been anaesthetised with either propofol/aIfentanil/N₂O or thiopentone/ halothane/N₂O. The sway velocity of the children was measured before premedication and 1, 2 and 3 h after the end of anaesthesia. Results show that sway velocity had returned to baseline values 3 h after the end of anaesthesia in all children who had received propofoI/alfentanil/N₂O and in 12 of the 15 children who had received thiopentone/halothane/N₂O. The quantified version of the Romberg test performed with eyes open or closed was not impaired after anaesthesia, compared with the control values, indicating that in children poor equilibrium is not compensated by vision. The clinical recovery with respect to the times to eye opening, to responding to command or to being fully awake did not differ between the two anaesthesia methods. On the basis of recovery assessed by postural stability, propofol/alfentanil/N₂O anaesthesia was not preferable to thiopentone/halothane/N_sO anaesthesia after minor paediatric otolaryngological surgery.     

Propofol and halothane versus sevoflurane in paediatric day-case surgery: induction and recovery characteristics

Background. The aim of this study was to compare the inductionand recovery characteristics associated with propofol inductionand halothane maintenance with sevoflurane anaesthesia in paediatricday surgery. Methods. In total, 322 children were assigned randomly to i.v.propofol induction and halothane/nitrous oxide maintenance orsevoflurane/nitrous oxide alone. The patients’ age, sex,and type of surgery were recorded, as were the times requiredfor anaesthetic induction, maintenance, recovery and time todischarge home. Postoperative nausea and vomiting, and the incidenceof adverse events during induction and recovery were also noted. Results. No significant differences were detected in age, sex,type of surgery performed or intraoperative opioid administration.Excitatory movement was more common during induction with sevoflurane.The mean time required for induction with propofol was 3.1 mincompared with 5 min in the sevoflurane group (P<0.001). Therecovery time was shorter in the sevoflurane group comparedwith propofol/halothane (23.2 vs 26.4 min, P<0.002). Theincidence of delirium in recovery was greater in the sevofluranegroup (P<0.001). There was no difference between groups inthe time spent on the postoperative ward before discharge home.On the postoperative ward the incidence of both nausea and vomitingwas significantly higher in the sevoflurane group (P=0.034).Five children were admitted to hospital overnight, none foranaesthetic reasons. Conclusions. The increased incidence of adverse events duringinduction, postoperative nausea and vomiting and postoperativedelirium in the sevoflurane group suggests that sevofluraneis not ideal as a sole agent for paediatric day case anaesthesia. Br J Anaesth 2003; 90: 461–6     

Respiratory effects of nitrous oxide during halothane or enflurane anaesthesia in children

The respiratory effects of nitrous oxide (N2O) were studied during halothane and enflurane anaesthesia in 12 children (mean age 46.4 +/- 29.3 months, mean weight 15.3 +/- 4.2 kg) during surgery under continuous extradural anaesthesia. Four equipotent anaesthetic states were studied in random order: 1) halothane 1 MAC in oxygen, 2) halothane 0.5 MAC + 50% N2O, 3) enflurane 1 MAC in oxygen, 4) enflurane 0.5 MAC +50% N2O. End-tidal fractions of CO2 (PetCO2) and halothane and enflurane were measured using infrared analysers. The respiratory variables (tidal volume VT, minute ventilation VE, respiratory frequency F, inspiratory time Ti, mean inspiratory flow VI, effective inspiratory time Ti/Ttot) were measured using a pneumotachograph. Significant changes were observed between the four states for VE, VI, F and PetCO2, whereas the values of VT, Ti and Ti/Tot did not differ significantly. The respiratory depressant effect of 1 MAC of either halothane alone or of the mixture of halothane and N2O was very similar. During enflurane anaesthesia, PetCO2 was less increased when N2O was substituted for enflurane, owing to a significant increase in respiratory frequency. A marked decrease in VE together with an increase in PetCO2 was observed during enflurane anaesthesia (states 3 and 4) when compared to the corresponding states during halothane anaesthesia (states 1 and 2). The respiratory depressant effect of enflurane is greater than that of halothane in unpremedicated children, even when substituting N2O for an equal MAC fraction of enflurane.2+ The effect of N2O on respiratory patterns seems to depend on the inhalational agent used and/or on the vesting respiratory frequency.     

Peri-operative changes in plasma C3a and C5a concentrations in infants

It is well known that complement activation plays a key role in the development of pulmonary insufficiency; it is also well known that cortisol suppresses complement activation. By measuring the plasma concentrations of C3a and C5a, we investigated peri-operative changes in the activation of the complement system in 18 infants undergoing elective abdominal surgery. We also measured plasma cortisol concentrations to assess the peri-operative relationship between complement activation and the stress produced by multiple peri-operative factors following two anaesthetic techniques. Eighteen infants ranging in age from 1 to 11 months were randomly divided into two groups according to the anaesthetic technique used: Group 1 consisted of nine infants in whom general anaesthesia was maintained with halothane and nitrous oxide (N₂O) in oxygen, while Group 2 consisted of nine infants in whom general anaesthesia was maintained with fentanyl and N₂O in oxygen. Plasma C3a and C5a concentrations were higher in the fentanyl group than in the halothane group during the peri-operative period. Plasma cortisol concentration, in contrast, was lower in the fentanyl group both during and after surgery. The post-operative clinical course showed no significant intergroup differences between the two groups throughout the study. These observations suggest that the difference in peri-operative complement activation between the halothane and the fentanyl groups may have been due, in part, to different peri-operative stress responses. However, further studies are required to elucidate the precise causative mechanisms and the clinical implications of complement activation in infants.     

Single breath induction of anaesthesia, using a vital capacity breath of halothane, nitrous oxide and oxygen

Inhalational induction of anaesthesia, using a single vital capacity breath of 4% halothane in 66% nitrous oxide and 33% oxygen was evaluated in 100 unpremedicated outpatients. The technique was found to be acceptable to most (91%) of the patients studied, with a mean (SD) induction time (measured from beginning of inspiration to loss of 'eyelash reflex') of 83(21) seconds. Relative cardiovascular stability was a notable finding of the technique, with a slight decrease in the mean arterial pressure of only 10%. Anaesthetic induction time was unaffected by age, weight or smoking habits. The technique of single breath induction is therefore proposed as a safe and acceptable alternative to intravenous induction in co-operative adult patients.     

Propofol–nitrous oxide versus thiopentone–isoflurane–nitrous oxide anaesthesia for uvulopalatopharyngoplasty in patients with sleep apnea

A randomized prospective study was performed to compare the recovery in 41 patients undergoing uvulopalatopharyngoplasty (UPPP) with either propofol-nitrous oxide-fentanyl or thiopentone-isoflurane-nitrous oxide-fentanyl anaesthesia. The patients were referred to UPPP after examination including polysomnography and otorhinolaryngological examination. The propofol group received propofol 2 mg·kg^-1 for induction followed by an infusion of 10 mg·kg^-1·h^-1 after intubation. The thiopentone-isofiurane group received 5 mg·kg^-1 of thiopentone for induction followed by isoflurane (0.5–2%) after intubation. Other medication was similar in both groups. In the propofol group the patients had a significantly better oxygen saturation during the first postoperative hour ( P < 0.05), and a higher rate of breathing ( P < 0.05), indicating a more rapid recovery of the physiologic control of breathing. Pain as measured by visual analogue score was lower ( P < 0.05) during the second postoperative hour compared with the isoflurane group. Apneic episodes occurred with similar frequency in both groups, and they were related to the severity of obstructive sleep apnea (OSA). We conclude that propofol is preferable to thiopentone-isofiurane in UPPP operations, because physiologic respiratory control recovers faster and postoperative pain is less intense.     

Recovery after single-breath halothane induction of anaesthesia in daycase patients

A single-breath technique of inhalational induction of anaesthesia allows intravenous induction agents to be avoided. We have investigated recovery from anaesthesia in 40 daycase patients, using tests of psychomotor function. Patients anaesthetised with inhalational induction awaken earlier than those who receive thiopentone, but not significantly earlier. There were no significant differences in postoperative psychomotor function between patients who received thiopentone and those who had inhalational inductions. Single-breath halothane, nitrous-oxide, oxygen induction is an alternative to intravenous induction in cooperative adults, but does not confer significant benefits in terms of recovery.     

Comparison of isoflurane and halothane on recovery from neuromuscular blockade using atracurium in infants with hepatic dysfunction undergoing major abdominal surgery

The effects of either isoflurane or halothane on recovery from neuromuscular blockade with atracurium in infants with hepatic dysfunction undergoing major abdominal surgery were studied. Neuromuscular blockade was assessed visually at minute intervals by 'train-of-four' using supra-maximal stimuli. The times to first and second increment and total requirement of atracurium in two groups of infants randomly allocated to receive either isoflurane or halothane for induction and supplementation were recorded. Fourteen patients completed the study, seven with isoflurane and seven with halothane. No evidence was found that recovery from neuromuscular blockade with atracurium was prolonged by isoflurane as compared to halothane.     

Ketamine boluses with continuous low-dose fentanyl for paediatric sedation during diagnostic cardiac catheterization

During cardiac catheterization, 202 children aged 1 month to 16 yrs were sedated intravenously half an hour after oral premedication with flunitrazepam 0.1 mg·kg^?1 (maximum dose 2 mg) to maintain spontaneous breathing and stable and calm conditions for the investigation. Standard fentanyl doses for induction and maintenance were 1 μg·kg^?1 and 1 μg·kg^?1·h^?1, respectively, for all patients. Requirements for supplementary ketamine for induction and maintenance of stable sedation were studied in five age groups (≤0.5 yr, >0.5–2 yr, >2.0–5.0 yr, >5.0–10.0 yr and >10.0 yr). Ketamine doses for induction were 1.5 ± 0.1, 1.5 ± 0.1, 1.2 ± 0.1, 0.9 ± 0.1 and 0.2 ± 0.1 (mean ± SEM) mg·kg^?1 in these age groups, respectively. Ketamine requirements for maintenance of sedation were 1.9 ± 0.1, 1.7 ± 0.1, 1.4 ± 0.1, 1.1 ± 0.1 and 0.2 ± 0.1 mg·kg^?1·h^?1 in the same age groups, respectively. Age dependency of ketamine requirement was shown; the older the patient the less was the need for supplementation. Intravenous sedation with low-dose fentanyl and ketamine after flunitrazepam premedication provided favourable anaesthesia for cardiac catheterization.