Anaesthesia for insertion of ear tubes in children: comparison of propofol, thiopentone and halothane

To determine the quality of anaesthesia and speed of recovery after propofol anaesthesia for myringotomy in children, 100 children 2–12 years were randomized to one of four anaesthetic regimens for induction/maintenance: thiopentone (STP) (5 mg·kg⁻¹)/halothane, propofol (3 mg·kg⁻¹)/halothane, halothane/halothane or propofol (3 mg·kg⁻¹)/propofol bolus (0.5 mg·kg⁻¹ every 3 min (10 mg·kg⁻¹·h⁻¹)). Nitrous oxide (70%) in oxygen (30%) was used to facilitate insertion of an intravenous catheter and was continued throughout the anaesthetic. We found that the incidence of intraoperative movement in response to surgical stimulation was significantly greater in the prop/prop group 32%, compared with the three other groups ( P <0.02). Although some recovery variables (time to response to questions, sit unaided, tolerate oral fluids, and discharge with fluids) were achieved more rapidly by the prop/prop group than the other three groups, the times to open eyes, obey commands and, most importantly, discharge from recovery without fluids did not differ between the prop/prop and the hal/hal groups. We conclude that there is little benefit in using propofol as an induction agent alone or in combination with a propofol maintenance anaesthetic for paediatric myringotomy and tube surgery.     

A comparison of propofol and other sedative use in paediatric intensive care in the United Kingdom

The retrospective study was designed to examine the safety of propofol against other sedative agents when used by infusion for the sedation of children requiring mechanical ventilation. One-hundred-and-ninety-eight patients were recruited. One-hundred-and-six received propofol and 92 received other sedative agents for durations of 30 min to 156 days and 13 min to 11 days respectively. The mean infusion rate of propofol was 3.39 mg·kg⁻¹·h⁻¹. Sixty-one of the 92 patients in the nonpropofol group received midazolam at a mean infusion rate of 0.4 mg·kg⁻¹·h⁻¹. Forty-one patients developed clinical metabolic acidosis with five falling into the pathological range as defined. Seventeen received propofol and 24 another sedative agent. Seventy-eight percent of patients that became acidotic were under the age of three. No patient who became acidotic was noted to have lipaemic serum. Three of four patients were recorded as having lipaemic serum received propofol, however two of these patients along with the patient that received midazolam also received Intralipid. Overall mortality was similar in both sedation groups with 27 deaths being recorded. Thirteen patients received propofol. Five nonfatal adverse events occurred, three in patients that had received propofol. The findings of the survey suggest that propofol compares favourably with other sedative agents when used for sedating children in a paediatric intensive care unit.     

Rectal paracetamol dosing regimens: determination by computer simulation

A pharmacokinetic dynamic simulation model was used to predict rectal paracetamol dosing schedules which would maintain steady state plasma concentrations of 10–20 mg·l⁻¹. These plasma concentrations of paracetamol are known to reduce fever. The conventional dosing schedule of 15 mg·kg⁻¹ four hourly was unsatisfactory. Steady state concentrations of 8–12 mg·l⁻¹ were only reached after 16 h. A loading dose of 50 mg·kg⁻¹ followed by 30 mg·kg⁻¹ six hourly achieved plasma concentrations of 9–18 mg·l⁻¹. Paracetamol is a mild analgesic. A higher plasma paracetamol concentration of 25 mg·l⁻¹ is known to give satisfactory analgesia to 60% of children after tonsillectomy. This concentration can be reached after a loading dose of 70 mg·kg⁻¹ and a maintenance dose of 50 mg·kg⁻¹ 8 hourly. Doses above 150 mg·kg⁻¹·day⁻¹ have been reported to cause reversible liver toxicity after 2–8 days and should not be sustained.     

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.     

Laryngeal mask airway placement in paediatric patients: a comparison of two general anaesthetic techniques

Guidelines for paediatric practice suggest that the laryngeal mask airway (LMA) is best inserted after a period of inhalational anaesthesia. This study compared the success rate and incidence of complications for LMA placement using two different techniques of general anaesthesia. Sixty ASA I or II patients between the ages of 19 months and 14 years of age were studied. In Group 1, anaesthesia was induced with propofol, 4 mg·kg⁻¹, and placement of the LMA was then attempted. In Group 2, anaesthesia was similarly induced with propofol, but the lungs were then ventilated with halothane in oxygen for placement of the LMA. Although limb movement occurred more often in Group 1 ( P < 0.001), there were no differences between the groups for other complications, nor for success in placing the LMA. We conclude that in paediatric patients, the LMA may be successfully placed using propofol, 4 mg·kg⁻¹ alone.     

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.     

Rectal midazolam as premedicant in children: a dose response study

Rectally administered midazolam has proved to be a reliable and acceptable way of premedicating children. In order to determine the optimal dose 80 children were randomized in a double-blind manner to receive one of four different dosages of midazolam (0.2–0.3–0.4–0.5 mg·kg⁻¹) in combination with atropine 0.02 mg·kg⁻¹ rectally. Observations before and after premedication showed no clinically relevant differences in ventilatory and cardiovascular parameters. Neither did the groups differ as regards acceptance of the mask or awakening from anaesthesia. Regardless of group the level of sedation was increased, but only children receiving 0.4 or 0.5 mg·kg⁻¹ of midazolam showed an increase in the level of anxiolysis. For this reason a low dose of midazolam (0.2 mg·kg⁻¹) can be used, except in cases where pronounced anxiolysis is required.     

A national survey of propofol infusion use by paediatric anaesthetists in Great Britain and Ireland

Background:  Since the introduction of propofol in 1977, it has been widely used for the induction and maintenance of anaesthesia and for sedation on the intensive care unit. Recently, case reports of suspected propofol infusion syndrome (PRIS) following short term infusions have been published. We set out to obtain a picture of the current use of propofol infusions by paediatric anaesthetists in Great Britain and Ireland.
Methods:  A questionnaire concerning the use of propofol infusions was sent to 388 paediatric anaesthetists.
Results:  A total of 242 (62%) replies were received. 26% of anaesthetists used propofol infusions with at least a monthly frequency. 136 (56%) anaesthetists thought that propofol infusions were of benefit in reducing postoperative nausea and vomiting. The majority of anaesthetists did not state a maximum infusion rate or length of infusion. Of those anaesthetists who answered the questions the maximum rate used was 30 mg·kg⁻¹·h⁻¹ and the longest time considered for an infusion was 72 h. Only 5 (2%) anaesthetists regularly used BIS monitoring, although 106 (44%) expressed a desire to use it if it was freely available in their hospitals. Modifications to infusions from 1% to 2% propofol were used by 38 (16%) anaesthetists and 28 (12%) used glucose infusions intra-operatively.
Conclusions:  There is a wide variety in the use of propofol infusions by paediatric anaesthetists. The mechanisms underlying PRIS are poorly understood and require further work to ensure propofol infusions are used appropriately for anaesthesia in children.     

Alterations of bacterial clearance induced by propofol

Background: The purpose of the study was to investigate the potential influence of the anaesthetic agent propofol on immune function in terms of systemic clearance and organ distribution of injected Escherichia coli in a rabbit model.
Methods: Defined numbers of E. coli (1.3×10⁸ colony-forming units, CFU) were injected intravenously 1 h after starting a 4-h infusion of the anaesthetic propofol (2 ml  ·  kg⁻¹  ·  h⁻¹, Disoprivan^® 1%; n=6)) or after saline application (n=6). As propofol is formulated in a 10% lipid emulsion, the lipid vehicle Intralipid^® (2 ml  ·  kg⁻¹  ·  h⁻¹; n=6) alone was investigated in a separate group. Parameters monitored were arterial pressure and rates of bacterial elimination from the blood. Three hours after bacterial injection, the animals were killed, and tissue samples of liver, spleen, lung, and kidney were collected for microbiological examinations.
Results: Compared to saline-treated animals, infusion of propofol induced increased accumulation of E. coli in lung and spleen, thus reflecting reticuloendothelial system dysfunction.
Conclusion: As the lipid emulsion by itself induced the same effects, the impaired immune function due to propofol is thought to be attributed to its solvent Intralipid^®.     

Comparison of computer-controlled administration of propofol with two manually controlled infusion techniques

Ninety women were studied in order to compare dose requirements and quality of anaesthesia between target-controlled infusion and two manually controlled infusion schemes for propofol administration: group I received target-controlled infusion for induction (4 μg.ml⁻¹ target blood concentration, increased by 2 μg.ml⁻¹ after 3 min if consciousness not lost), groups II and III received an induction bolus of propofol at infusion rates of 1200 or 600 ml.h⁻¹, respectively, until loss of consciousness. Anaesthesia was maintained with propofol target-controlled infusion in group I or by constant rate infusion in the other two groups. Computer simulations were used to calculate blood and effect-site propofol concentrations. Mean induction times (SD) were 78 (65) s in group I versus 51 (10) s and 62 (12) s in groups II and III, respectively (p < 0.05 between groups II and III). Mean induction doses were: 1.31 (0.44), 2.74 (0.56) and 1.77 (0.43) mg.kg⁻¹ and mean maintenance doses were 13.4 (3.55), 9.32 (1.71) and 9.97 (1.53) mg.kg⁻¹.h⁻¹ in groups I, II and III, respectively (p < 0.05 between all groups). There was a lower incidence of apnoea in group I than in groups II and III. There were no significant differences between the groups in other objective parameters of anaesthetic quality studied. Computer simulations showed an 'overshoot' in propofol blood and effect-site concentration with manual induction and significantly higher maintenance levels with target-controlled infusion.     

Comparison of propofol/alfentanil anaesthesia with isoflurane/N2O/fentanyl anaesthesia for renal transplantation

Total intavenous anaesthesia (TIVA) with propofol and alfentanil was compared with balanced anaesthesia (BA) in 30 uraemic patients undergoing renal transplantation. TIVA (n=15) was induced with propofol and alfentanil and maintained with propofol and alfentanil infusions, which were started immediately after induction. Thereafter the infusion rates were adjusted as needed. Ventilation was with oxygen in air. BA (n= 15) was induced with thiopentone and fentanyl and maintained with isoflurane/N20/fentanyl. Vecuronium was used for muscle relaxation in both groups. Mean infusion rates for propofol and alfentanil were 10 1.8 mg kg^-1 h^-1 and 70 9 μg kg^-1 h^-1, respectively. To control hypertension during TIVA, larger amounts of propofol and alfentanil were needed and slower recovery was observed than in previous studies in ASA 1–2 patients. Also, significantly more vecuronium was needed during TIVA than during BA ( P < 0.05). The recovery parameters were similar in both groups, except for the occurrence of nausea, which was less after TIVA. In conclusion, TIVA had no clinical advantages over BA.     

Comparison of diclofenac and tenoxicam for postoperative analgesia with and without fentanyl in children undergoing adenotonsillectomy or tonsillectomy

127 children scheduled for elective tonsillectomy or adenotonsillectomy were studied. Anaesthesia was induced with propofol and maintained with a volatile agent. At induction the child received either rectal diclofenac 1 mg·kg⁻¹ with or without fentanyl 0.75 μg·kg⁻¹ i.v., or intravenous tenoxicam 0.4 mg·kg⁻¹ with or without fentanyl 0.75 μg·kg⁻¹ i.v. Blood loss was measured peroperatively. Nausea and vomiting scores, sedation scores and pain scores were recorded in the recovery room, at one, two, four and eight h postoperatively and at discharge. There were no significant differences in blood loss between the groups or between nausea and vomiting scores. Pain scores in the tenoxicam without fentanyl group were significantly higher in recovery ( P <0.05) than the diclofenac group without fentanyl and both fentanyl groups. This group required supplemental analgesia earlier although this was not significant. The pain scores in the diclofenac with fentanyl group were significantly lower at one h and four h than the group receiving diclofenac alone ( P =0.008 and 0.02 respectively).     

Renal replacement therapy for acute renal failure: a survey of practice in adult intensive care units in the United Kingdom

This study surveyed current practice in adult intensive care units in the United Kingdom in three key areas of renal replacement therapy when used for acute renal failure: type of therapy used, typical treatment dose and anticoagulation.
Responses were received from 303 (99%) of the 306 intensive care units. 269 units (89%) provide renal replacement therapy for acute renal failure. Most (65%) use continuous veno-venous haemofiltration as first-line therapy in the majority of patients, though continuous veno-venous haemodiafiltration is used by 31% of units. For haemofiltration, the median typical treatment dose (interquartile range [range]) is 32 ml.kg⁻¹.h⁻¹ (28.6–35.7 [14.3–85.7]), with 49% using a treatment dose of 35 ml.kg⁻¹.h⁻¹ or greater. For haemodiafiltration, the median typical treatment dose (interquartile range [range]) is 44 ml.kg⁻¹.h⁻¹ (28.6–57.1 [21.4–120.7]), with 67% using a treatment dose of 35 ml.kg⁻¹.h⁻¹ or greater. The vast majority of intensive care units use intravenous unfractionated heparin (96%) or epoprostenol (88%) for anticoagulation. Dosage and monitoring of these two agents vary markedly between units. No units use citrate anticoagulation. These results reveal a wide variety of practice in the delivery of renal replacement therapy between intensive care units in the United Kingdom.     

Oral midazolam compared with diazepam-droperidol and trimeprazine as premedicants in children

Ninety children were assigned randomly to one of three groups for premedication with oral midazolam 0.5 mg·kg⁻¹, diazepam 0.25 mg·kg⁻¹ with droperidol 0.25 mg·kg⁻¹, or trimeprazine 2 mg·kg⁻¹. On arrival at the anaesthetic room, anxiolysis was satisfactory in 26 out of 29 (90%) children who received midazolam compared with 23 out of 29 (79%) who received diazepam-droperidol and 18 out of 29 (62%) who received trimeprazine ( P <0.05); at induction of anaesthesia these proportions were 24 out of 29 (83%), 16 out of 29 (55%) and 11 out of 29 (40%) respectively ( P <0.001). When individual groups were compared, anxiolysis was significantly greater in the midazolam group compared with the trimeprazine group on arrival in the anaesthetic room ( P <0.05) and significantly greater in the midazolam group than in either the diazepam-droperidol or the trimeprazine groups at induction of anaesthesia ( P <0.05 and P <0.001 respectively). There were no significant differences in times to early recovery between the groups (25.4, 24.4 and 28.5 min). Analysis of behavioural questionnaires completed two weeks after hospitalization showed a trend towards fewer postoperative behavioural disturbances in children who received midazolam or diazepam-droperidol compared with trimeprazine (47 and 44% vs 75%); when the results for the benzodiazepine-containing premedicants were combined, the difference between these groups and trimeprazine was statistically significant ( P <0.05).     

Tracheal administration of atropine in children—effect on heart rate

Forty-one ASA I patients, aged 2–6 years, anaesthetized for elective ear, nose and throat surgery, were studied in a double blind and randomized fashion in order to examine the effect of tracheally administered atropine 0.02 mg·kg⁻¹ or saline 0.9% on heart rate. In patients receiving atropine heart rate increased 8.8 beats·min⁻¹ (8.7%) and 16.2 beats·min⁻¹ (16.0%) after 3 and 5 min respectively. No increase in heart rate was seen in the saline group. Because of the late onset of action and only moderate increase in heart rate it is concluded that tracheal administration of atropine 0.02 mg·kg⁻¹ to children is insufficient in emergency situations.     

The optimum bolus dose of remifentanil to facilitate laryngeal mask airway insertion with a single standard dose of propofol at induction in children

The purpose of this study was to determine the optimal bolus dose of remifentanil required for the successful insertion of the laryngeal mask airway during propofol induction in children without a neuromuscular blocking agent. Twenty-six paediatric patients, aged 3–10 years, requiring anaesthesia for short ambulatory surgery were recruited. A predetermined bolus dose of remifentanil was injected over 30 s, followed by propofol 2.5 mg.kg⁻¹ over 10 s. The bolus dose of remifentanil was determined by a modified Dixon's up-and-down method, starting from 0.5 μg.kg⁻¹ (0.1 μg.kg⁻¹ as a step size). Laryngeal mask insertion was attempted 90 s after the end of remifentanil injection and the response of patients was classified as either 'movement' or 'no movement'. The bolus dose of remifentanil at which there was a 50% probability of successful laryngeal mask insertion (ED₅₀) during induction with 2.5 mg.kg⁻¹ propofol was 0.56 (0.07) μg.kg⁻¹ in children without a neuromuscular blocking agent. From probit analysis, the ED₅₀ and ED₉₅ of remifentanil were 0.52 μg.kg⁻¹ (95% confidence limits, 0.42–0.62 μg.kg⁻¹) and 0.71 μg.kg⁻¹ (95% confidence limits, 0.61–1.40 μg.kg⁻¹), respectively.     

Influence of anesthetic management on quality of magnetoencephalography scan data in pediatric patients: a case series

Background:  Magnetoencephalography (MEG) is increasingly used in the presurgical evaluation of pediatric seizure patients. Many pediatric patients require sedation or anesthesia to tolerate these exams. However, the available literature on anesthetic management in this population is very limited.
Methods:  We retrospectively reviewed the records of all patients who underwent MEG scanning at our institution with regard to the interaction of anesthetic management and quality of scan data.
Results:  High-dose propofol infusions (≥200 μg·kg⁻¹·min⁻¹) were associated with high frequency artifacts that interfered with the identification of epileptiform discharges. Lower-dose propofol infusions (≤100 μg·kg⁻¹·min⁻¹) did not produce artifacts but required co-administration of fentanyl to prevent patient motion. Dexmedetomidine infusions were not associated with signal artifacts and prevented patient motion very well in our initial patients and became our standard technique.
Conclusion:  In our experience, dexmedetomidine infusions are preferable to propofol-based techniques for pediatric MEG scans due to the absence of adverse effect on interictal activity.     

Onset of neuromuscular blockade and intubating conditions one minute after the administration of rocuronium in children

In a blinded randomized study intubating conditions were compared at one min following intravenous induction with propofol and either suxamethonium 1.0 mg·kg⁻¹, or rocuronium 0.6 mg·kg⁻¹. Onset time to maximal twitch depression, % block at one minute and clinical duration (time to 25% recovery) were measured. Sixty children undergoing elective tonsillectomy were recruited. Onset time [42 s ( SD 11 s)] and clinical duration [3.3 min ( SD 1.0 min)] in the suxamethonium group was significantly ( P <0.001) less than in the rocuronium group [92 s (41 s)] and [24.2 min (6.6 min)] respectively. The median twitch height at one minute for suxamethonium was 0% (range 0–8%) and significantly greater ( P <0.001) at 5% (range 0–22%) for rocuronium. Despite this there was no difference in the intubating conditions at one minute with 25 excellent/5 good in the suxamethonium group and 27 excellent/3 good in the rocuronium group. We conclude that rocuronium 0.6 mg·kg⁻¹ gives optimal intubating conditions at one minute in children.     

The analgesic efficacy of an injectable prodrug of acetaminophen in children after orthopaedic surgery

The analgesic efficacy and safety of propacetamol, an injectable prodrug of acetaminophen, (paracetamol) were studied in 87 children (36 boys, 51 girls; age 6–13; mean age 9.5 years) immediately after limb surgery. Using a double-blind, randomized, parallel group design, the effects of a single IV infusion of 30 mg·kg⁻¹ propacetamol (i.e. 15 mg·kg⁻¹ acetaminophen) were compared with a single injection of placebo (PL). Efficacy was assessed on pain scores rated on a four-point verbal scale, a five-point visual scale (faces) and on a four-point relief verbal scale before administration (T0) and 0.25, 0.5, 1, 2, 3, 4, 5, 6 h after administration. At the end the global efficacy was rated by the physician on a five-point verbal scale. Propacetamol was statistically superior to placebo on all assessment criteria. Seven side-effects were recorded: five in the propacetamol group and two in the placebo group. 30 mg·kg⁻¹ propacetamol provided a significantly greater analgesic effect than placebo in children after orthopaedic surgery.     

A comparison of the effects of fentanyl and propofol on left ventricular contractility during myocardial stunning

Background : The intravenous anaesthetic propofol has been shown to possess free radical scavenging activity and calcium channel blocking effects in a number of in vitro models. We decided to compare the effects of propofol with those of fentanyl on myocardial contractility during and after ischaemia to determine whether propofol could protect the heart and improve recovery of ventricular contractile function in open-chested dogs.
Methods : Twenty adult beagles were acutely instrumented, under halothane anaesthesia, to measure ECG; aortic, left ventricular pressures; cardiac output; coronary flow; and segmental lengths in the regions perfused by the left anterior and left circumflex coronary arteries. After surgery and a stabilisation period halothane anaesthesia was terminated and fentanyl (100 μg. kg^-1 bolus followed by 2 μ.kg^-1·min^-1 infusion; n=10) or propofol (5 mg. kg^-1 bolus followed by 0.3 mg· kg^-1 min^-1 infusion; n=10) anaesthesia commenced. After a stabilisation period the LAD coronary artery was occluded for 10 min and then reperfused for 3 h. Measurements were taken throughout the protocol.
Results : We found no significant difference in recovery of contractile function between propofol and fentanyl as assessed by normalised preload recruitable work area (50±10 vs 47±16%), normalised systolic shortening (36±12 vs 48±14%) and peak left ventricular dP/dt (1665±276 vs 1846±151 mmHg.s^-1) at the end of reperfusion.
Conclusion : We conclude that at the concentration used in this study propofol shows no improvement in contractility during "stunning" when compared to fentanyl.