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Is TIVA with remifentanil/propofol superior to sevofluran / N2 O regarding PONV in children undergoing squint surgery?
Abstract
Background: 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/N(2)0. Additionally, little is known, whether the type of operation or the muscle which is operated on has any influence with respect to PONV. Methods: 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 mu g kg(-1) min(-1) over 2 min (loading phase), followed by 3 mg kg(-1) propofol along with 30% O-2 in air. After endotracheal intubation anaesthesia was maintained initially with remifentanil 0.25 mu 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% O-2 in N2O. After endotracheal intubation anaesthesia was maintained with sevoflurane 1.0-1.5 MAC along with 30% O-2 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. Results: 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). Conclusions: TIVA with propofol/remifentanil proved to be a suitable form of anaesthesia for children in this setting. Propofol showed advantages over 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.
... [14] This outcome has also been reported in a few German language studies. [3,15,16] Wolf et al. advocate a liberal PONV prophylaxis including TIVA in high-risk patients, as identified by the POVOC score > 2, while Biallas et al. found no difference in POV between the propofol and sevoflurane groups. [3,16] Several authors have confirmed the useful effects of dual prophylaxis with dexamethasone and ondansetron for squint surgery. ...
Background and Aims
Squint surgery is a risk factor for postoperative vomiting (POV) in children. This study was designed to compare the incidence of POV in children undergoing strabismus surgery under balanced anesthesia with sevoflurane versus intravenous anesthesia with propofol.
Material and Methods
In this prospective randomized controlled study conducted in a tertiary care ophthalmology hospital, 70 ASA I-II children aged 1-12 years undergoing strabismus surgery were randomized to two groups –Group S (sevoflurane-based anesthesia) and Group P (propofol-based anesthesia) for maintenance. The surgical details, intraoperative hemodynamic parameters, recovery characteristics, and emergence delirium were recorded. Any episode of postoperative vomiting in the 0-2 hours, 2-6 hours, and 6-24 hours period was noted. Rescue antiemetic was administered if there was more than one episode of vomiting.
Results
Both the groups were similar with respect to demographic and surgical details. The average duration of surgery was 118.2 ± 41.88 min in group S and 137.32 ± 39.09 min in group P ( P = .05). Four children in group S (11.4%) and one child in group P (2.9%) had POV in the first 24 hours but this was not statistically significant ( P = .36). The median time to discharge from post anesthesia care unit was significantly less ( P = .02) in the P group (50 min) than in the S group (60 min).
Conclusion
Propofol-based anesthesia does not offer advantage over sevoflurane, in reducing POV after squint surgery, when dual prophylaxis with dexamethasone and ondansetron is administered. It, however, reduces the duration of stay in the post anesthesia care unit.
... patients received intraoperative dexamethasone, which may have altered the results. In a randomised, blinded study of children undergoing strabismus surgery who were anaesthetised with either remifentanil and propofol, or sevoflurane and nitrous oxide, the investigators noted that 39% and 61% of children, respectively, had vomited.[41] Table II. ...
Remifentanil is a synthetic opioid that was developed in the early 1990s and introduced into clinical use in 1996. It is a methyl ester and is metabolised by nonspecific tissue and plasma esterases. Consequently, it is a drug that undergoes rapid elimination and has a reported terminal elimination half-life of between 10 and 35 minutes. Because there is no drug accumulation, the context-sensitive half-time remains constant; thus the pharmacokinetics of the drug do not change regardless of the duration of infusion. The organ-independent elimination of remifentanil, coupled with the fact that its clearance is greater in infants and neonates compared with older age groups, make its pharmacokinetic profile different from any other opioid. In addition, its unique metabolism confers predictability in its clinical use. Like other opioid mu receptor agonists, remifentanil provides dose-dependent analgesia, while the adverse effects of this drug, e.g. respiratory depression, are also thought to be dose related. The incidence of nausea and vomiting appear similar to other opioids. Its rapid and consistent metabolism regardless of duration of infusion has made remifentanil an attractive analgesic/anaesthetic option for paediatric care providers.
Following strabismus surgery under sevoflurane anesthesia children often experience emergence agitation (EA) and postoperative vomiting (POV). This study compared the effects of premedication with intranasal dexmedetomidine, midazolam, and placebo on postoperative EA and POV.
Our primary goal, to relieve patients from pain and stress, can be achieved with these few (!) drugs presented here that are easy to monitor and with high tolerance. For repositioning in child surgery and for imaging procedures there is no requirement any longer for intubation-/larynx mask narcosis which is associated with a high rate of complications. Due to the very effective procedure and precise timing the relationship to diagnostic as well as consulting departments could be significantly improved. Parents experience less stress and are much more content and co-operative. In the light of upcoming changes in our health system the drugs presented here are well suited to be used in the day clinic due to their immediate mode of action, easy monitoring and rapid awakening of patients.
Since venous cannulation in children has become easier and extensive experience has been gained with total intravenous anaesthesia (TIVA) in adults, the interest in TIVA for children has recently increased. One of the most interesting agents for TIVA in paediatric anaesthesia is propofol. The pharmacokinetic and pharmacodynamic data for modern intravenous drugs is poor. Because the interpatient variability is relatively large, pharmacokinetic data can only pro-vide guidelines for the dosage of propofol. Propofol has a rapid and smooth onset of action and is as easy to titrate in children as in adults. Propofol can be excellently controlled. Severe haemodynamic side effects are missing in healthy children and plasma is cleared rapidly of propofol by redistribution and metabolism. There is no evidence of significant accumulation, not even after prolonged infusion times. Because propofol has no analgetic properties it must be combined with analgetics or a regional block for all painful procedures. The combination with the ultra-short acting remifentanil-is a major advantage, but 4 requires effective analgetic concepts for painful procedures. In comparison the combination of propofol with long acting opioids abolishes some of the favourable properties of propofol. TIVA has an important significance in paediatric anaesthesia for diagnostic and therapeutic procedures, especially where these have to be repeated. In day-case anaesthesia TIVA has advantages for all short procedures and for ENT and ophthalmic surgery even after prolonged infusion children have an short recovery time. There is no evidence of agitation or other behavioural disorders after TIVA with propofol in paediatric anaesthesia. Propofol has antiemetic properties. TIVA with propofol can be combined with regional anaesthesia advantageously to provide long-lasting analgesia after surgery. TIVA with propofol has been used successfully for sedation of spontaneously breathing children for MRI and CT and other procedures with open airways like bronchoscopy or endoscopy. Propofol facilitates endotracheal intubation. without the use of muscle,relaxants. Of course, in malignant hyperthermia TIVA will continue to be the technique of choice. Nothing is known about awareness under TIVA in paediatric patients. TIVA must be considered by comparison with the volatile agents. The use of ultra-short acting agents may cause problems such as awareness,vagal response, involuntary movements and in some cases slow recovery after prolonged infusion of propofol. But it is not known exactly how often this happens during paediatric anaesthesia. With TIVA an effective postoperative analgesia must be provided. Newer administration techniques such as the target-controlled infusions or closed-loo p control systems are under development and will help to minimise the potential risk of overdosage with TIVA in paediatrics. At the present TIVA is an interesting and practicable alternative to volatile anaesthesia for pre-school and school children. TIVA with propofol in infants younger than 1 year old requires extensive experience with TIVA in older children and with the handling of this special age group and should be undertaken with maximum precautionary measures.
Many aspects of modern medicine, including the administration of anesthetic agents during general surgery, remain unautomated and reliant on the vigilance of the attending clinicians. In other fields where failures can have catastrophic consequences, such as the aviation and nuclear power industry, automated control regimens have been adopted to reduce the risks and improve performance.
In this paper we discuss many aspects of the implementation of a complete automated system for intravenous anesthetic drug infusion based on feedback from electroencephalography (EEG) readings. The system software in its entirety consists of approximately 22K lines of Scheme code and features a client-server implementation interfacing medical devices with a portable graphical user interface. The user interface runs on both mobile devices and dedicated medical flat panel displays.
The strengths of the Scheme functional language have been leveraged to build a robust maintainable modular system with extensive testing facilities to mitigate the inherent safety hazards associated with the application.
The use of total intravenous anaesthesia (TIVA) in children has become a popular technique for the induction and maintenance of anaesthesia following the introduction of newer short-acting drugs and more elaborate delivery systems. Advances in microprocessor technology and increased complexity of pharmacokinetic modelling have further refined TIVA to target controlled infusions (TCI). TCI delivery systems offer a continuously variable rate of intravenous drug administration, conferring advantages including greater haemodynamic stability, a stable depth of anaesthesia, and a rapid recovery with a low incidence of post-operative nausea and vomiting. This review will describe the development of TIVA and TCI for paediatric anaesthesia, the pharmacology of the common agents used, and possible future directions for the use of TIVA.
Although several hypnotic and opioid drugs are suitable for administration by continuous intravenous infusion, it is somewhat disquieting to realize just how little we know of their concentration–effect relationships during the early years of life; there remains great scope for clinical research in this area. Nevertheless, in the past few years we have gained sufficient information about the pharmacology of suitable drugs to formulate appropriate infusion dosage algorithms for children older than 2 years of age. Hence, target-controlled infusions (TCI) are becoming a practical proposition in paediatric anaesthesia. This review concentrates on the pharmacokinetics and pharmacodynamics of propofol, remifentanil and alfentanil when given by infusion to children. Evidence-based practical guidelines are given to enable manual infusion schemes to be utilized, although it is envisaged that commercially available TCI systems for young children will be available within a few years.
Major cardiac complications presenting as myocardial infarction, myocardial ischemia, cardiac failure, or life-threatening
dysrhythmias contribute significantly to perioperative morbidity and mortality. Preventive strategies are of major importance
since even despite adequate treatment these events are associated with poor outcome.
We aimed to investigate the effects of dexmedetomidine premedication before intravenous infusion of ketamine in agitated children undergoing strabismus surgery.
We enrolled 60 agitated pediatric patients, aged 4.5-11 years. The patients were randomly allocated to one of two anesthesia regimens. Group D patients were premedicated with a single dose of intravenous dexmedetomidine 0.5 μg/kg whereas group P patients received a placebo. Patients in both groups were administered intravenous ketamine 1 mg/kg i.v. over 1 min followed by a continuous infusion of ketamine 1-3 mg/kg/h i.v. (n = 30). Patients were intubated after receiving fentanyl 1 μg/kg and rocuronium bromide 0.5 mg/kg.
21 (70%) patients in group D did not show the oculocardiac reflex (OCR) versus 7 (23%) in group P (p = 0.0006). The preoperative and postoperative agitation scores (p = 0.0001 and p = 0.03, respectively), the score on the Faces Pain Scale during awakening [3.0 (interquartile range, IQR 2.0-4.0) in group D and 0.0 (IQR 1.0-2.25) in group P] (p = 0.001) and at the 60th postoperative minute [IQR 2.0 (1.5-3.0) in group D and 2.0 (IQR 1.5-3.0) in group P] (p = 0.004), sore throat (26.6% in group D and 60% in group P) (p = 0.01) and analgesic requirement (20% in group D and 53% in group P) (p = 0.01) in group P were significantly higher than in group D. The Ramsay Sedation Score (RSS) in group D was significantly higher than in group P during awakening [2.0 (2.0-2.0) in group D and 4.5 (4.0-5.0) in group P] (p = 0.0001).
Dexmedetomidine premedication followed by intravenous infusion of ketamine was effective in decreasing OCR, agitation, pain, analgesic requirement in agitated children undergoing strabismus surgery.
Mechanically ventilated pediatric intensive care patients usually receive an analgesic and sedative to keep them comfortable and safe. However, common drugs like fentanyl and midazolam have a long context sensitive half time, resulting in prolonged sedation and an unpredictable extubation time. Children often awake slowly and struggle against the respirator, although their respiratory drive and their airway reflexes are not yet sufficient for extubation. In this pilot study, we replaced fentanyl and midazolam at the final phase of the weaning process with remifentanil and propofol. Twenty-three children aged 3 months-10 years were enrolled. Remifentanil and propofol revealed throughout excellent or good weaning conditions with rapid transition from hypnosis to the development of regular spontaneous breathing, airway protective reflexes, and an appropriate level of alertness. Extubation time following discontinuation of the remifentanil and propofol infusion was only 24 ± 20 min (5-80 min). We conclude that the combination of remifentanil and propofol is a promising option to improve the weaning conditions of pediatric intensive care patients. Randomized controlled trials are needed to compare remifentanil and propofol with conventional weaning protocols.
Emergence following termination of a general anesthetic depends on the effect site concentration (C(e)) of the drug declining to an awakening value (C(e)-awake). C(e)-awake has been described in adults, but is unknown in children.
To determine C(e)-awake in children following a target-controlled infusion (TCI) of propofol and to assess a C(e)-driven TCI system's ability to predict times to emergence from anesthesia.
Subjects undergoing elective surgery, aged 3 months to <10 years were recruited into three age-stratified groups. A target C(e) of 3-4 microg x ml(-1) was selected for induction and subsequently titrated to patient response and surgical stimulus. Preoperative acetaminophen, a remifentanil infusion and regional anesthesia were permitted for supplemental analgesia. State Entropy (SE) was monitored from induction to emergence. Emergence was defined as the time of first purposeful spontaneous movement (PSM). Time zero was defined as the end of propofol infusion. Based on a pilot study, a C(e)-awake of 1.9 microg x ml(-1) was chosen as the wake-up threshold used by the software to predict emergence times. Results: Data was collected for 90 of 104 recruited patients. PSM occurred at a mean (sd) C(e) of 2.0 (0.5) microg x ml(-1) and an SE of 79 (11). There were no differences between age groups. A wide variation in emergence time was observed, with a mean (sd) of 16.9 (7) min, and a trend to more rapid emergence in older subjects.
A predicted C(e)-awake of 2.0 microg x ml(-1) in children aged 3 months to <10 years was identified with the selected model. For expert users of propofol in children, during shorter surgical procedures, TCI predicted emergence times do not offer significant clinical advantages.
Strabismus surgery is frequently performed operation in children. Despite improvements in anesthetic and surgical technique, postoperative vomiting (POV) after pediatric strabismus surgery is still being experienced by 41-88% when antiemetic prophylactics are not administered. Various antiemetics are currently available for the prevention and treatment of POV after strabismus surgery in children. Many studies have been conducted using therapeutic regimens to reduce POV. These drugs include traditional antiemetics (droperidol, metoclopramide, scopolamine, dixyradine, and dimenhydrinate), non-traditional antiemetics (dexamethasone, propofol, clonidine, midazolam, and lidocaine), and antiserotonins (ondansetron, granisetron, tropisetron, dolasetron, and ramosetron). Antiserotonins are more effective than traditional antiemetics, but these drugs are not entirely effective, perhaps because most of them act through the blockade on one type of receptor. Combination antiemetic therapy with antiserotonin (ondansetron, granisetron) plus droperidol or dexamethasone is highly effective for the prophylaxis against POV. Non-pharmacological techniques include acustimulation, acupressure, and acupuncture at P6 (Nei-Kuwan) point, Korean hand point (K-K9), and BL-10 (Tianzhu)-BL-11 (Dazhu)-GB-34 (Yanglinquan) points. For the treatment of established POV, antiserotonin (granisetron) is more effective than traditional antiemetics (droperidol, metoclopramide). Clildren undergoing strabismus surgery should be considered to receive these clinical strategies as mentioned above for the prevention and treatment of POV.
Maintaining spontaneous respiration during intravenous anesthesia for investigative and surgical procedures may avoid the need for airway instrumentation and reduce the risk of desaturation. In addition, when performing airway endoscopic procedures in children, maintaining spontaneous respiration while using intravenous anesthesia can reduce the need for endotracheal intubation. This facilitates improved access to the smaller airway, allows assessment of the dynamic function of the airway, and reduces exposure of personnel to inhaled anesthetic agents.
Anesthetic hypnotic and analgesic agents are potent dose-dependent depressants of respiration. Infants have historically been considered to be at a higher risk of respiratory depression, especially from opioid analgesics. However, recent evidence suggests that infants and younger children outside the neonatal period are more resistant to the effects of remifentanil, even when combined with propofol. Spontaneous respiration can be maintained at doses adequate to suppress somatic responses to painful procedures. The large inter-individual variation in respiratory depressant effects necessitates individualized dose titration. The drug dose is more linearly related to variation in the respiratory rhythm and respiratory rate than to minute volume or end-tidal carbon dioxide. Apneic episodes are less likely when respiratory depressant drugs are administered slowly, as this allows time for the end-tidal carbon dioxide level to rise to a new apneic threshold. Hypnotic anesthetics and opioid analgesics act synergistically to cause respiratory depression and suppression of the somatic response.
Spontaneous respiration can be maintained when anesthetizing children using intravenous anesthesia.
In the past few years, there have been many changes in ophthalmic anaesthesia. Application of drugs in general anaesthesia with excellent controllability enhances patient safety and allows a more efficient OR-management. Regional anaesthesia is gaining widespread use for ophthalmic surgery, especially topical anaesthesia for cataract surgery. Patients for ophthalmic surgery concomitantly often display high age and a high level of co-morbidity and, therefore, belong to the anaesthesiological risk groups ASA III-IV. Life-threatening adverse events including cardiovascular depression are associated with general and regional anaesthesia. Intervention by anaesthesiologists is frequently required for treatment of hypertension or dysrhythmias, and sedation. Thus, monitored anaesthesia care ("standby") is justified. Drugs applied for regional and general anaesthesia may change intraocular pressure. There are a lot of publications about the impact of anaesthesia on intraocular pressure (IOD), however, few on the effects of anaesthesia on pulsatile ocular blood flow. it has to be kept in mind that the effects of anaesthesia on intra-ocular pressure and pulsatile ocular blood flow may diverge. To avoid an increase of the IOD, especially during anaesthesia induction, drugs, such as succinylcholin, rocuronium and opiates, in particular remifentanil, can be applied. In addition, the use of the laryngeal mask may be advantageous compared to general anaesthesia associated with laryngoscopic tracheal intubation. The management of patients treated with anticoagulants and antiplatelet agents, has to be taken on the balance of risks. There are risks not only in continuing therapy, but also in discontinuing it perioperatively. Postoperative nausea and vomiting (PONV) remains a distressing and common problem after strabismus repair in particular in children. The incidence of PONV depends on the type of ophthalmic surgery and drugs applied. To reduce PONV in ophthalmic surgery, application of long-lasting opiates should be avoided, and non-opiate analgesics and, depending on the kind of operation, antiemetic prophylactics are recommended.
A 16-month-old baby with myotonic dystrophy underwent an open Nissen fundoplication and gastrostomy insertion under general anesthesia with an epidural. Postoperative care was managed on the pediatric intensive care unit for the first 6 h. She was then discharged to the ward, where she continued to make an uncomplicated recovery. Other anesthetic management that has been used in children with myotonic dystrophy is discussed.
Immediate postoperative adjustment after adjustable-suture strabismus surgery has been suggested as a viable alternative to the classic adjustment that is performed, usually within 6 to 24 hours after surgery. The purpose of this study was to compare the immediate postoperative eye measurements with those taken 24 hours postoperatively and to determine whether there was any significant difference between the 2 measurements.
This was a prospective study of strabismus patients who were candidates for muscle surgery using the adjustable-suture technique. All patients received a total intravenous general anesthesia, which allowed rapid recovery of consciousness. Measurements using the simultaneous prism cover test were obtained in the recovery room immediately after the patients regained consciousness and again 24 hours after surgery. Both measurements were taken before adjustment and were compared.
A total of 25 patients were studied. The postoperative alignment changed significantly during the first 24 hours in 84% of our patients. The mean drift in alignment during the first 24 hours measured 7.2 +/- 4.3 prism diopters and was significantly different from 0 ( P < 0.001).
The immediate postoperative ocular alignment after adjustable strabismus surgery is significantly different from the 24 hours postoperative alignment. This difference was noticed despite using an anesthesia protocol that allowed rapid recovery and full regaining of consciousness shortly after the conclusion of surgery. This early drift should be taken into consideration if adjustment is to be made in the immediate postoperative period.
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.
To investigate the incidence of the oculocardiac reflex (OCR), and of postoperative nausea and vomiting (PONV) in adults undergoing strabismus surgery.
Adults (18-86 yr) undergoing inpatient strabismus surgery received 10 micrograms.kg-1 atropine and 10 micrograms.kg-1 altentanil iv and were randomly allocated to: (A) 5 mg.kg-1 thiopentone iv, isoflurane/N2O maintenance; (B) 3 mg.kg-1 propofol iv, propofol/N2O maintenance (10-14 mg.kg-1.hr-1); 3 mg.kg-1 propofol iv, propofol/air/O2 maintenance (10-14 mg.kg-1.hr-1). Analyses were with the number-needed-to-treat/harm.
In 97 adults the absolute risk of OCR (13-20%) and PONV (21-31% after 24 hr) was low, with no differences between groups. Number-needed-to-treat to prevent PONV with propofol with or without N2O compared with thiopentone-isoflurane was 7 to 11. Number-needed-to-harm for one OCR with propofol compared with thiopentone-isoflurane was 17.
Adults undergoing strabismus surgery with prophylactic atropine had a low risk of OCR and PONV, independent of the anaesthetic technique used.
Objective: The present study investigates the effectivity and the incidence of side effects of sufentanil-supplemented propofol versus isoflurane anaesthesia in children undergoing elective strabismus surgery. Methods: 130 children (aged 3-11; ASA I-II) were randomly allocated to one of four groups. In group 1 and 2, anaesthesia was induced with 2 mg/kg propofol and maintained with 15-20 mg/kg x h propofol and 30% O 2 in air (group 1) or 10-15 mg/kg x h propofol in N 2O (group 2). After induction with either 2 mg/kg propofol (group 3) or 5 mg/kg thiopentone (group 4), anaesthesia was maintained with 0.8-1.5 Vol% isoflurane and N 2O in 30% O 2 in these groups. All children were orally premedicated with midazolam and atropine and received a single dose of intravenous sufentanil (0.5 μg/kg) and atracurium (0.5 mg/kg) prior to intubation. Heart rate, mean arterial blood pressure and pulse oximetry were registered 5 min prior and after intubation as well as 10 min before and 5 min after extubation. The incidence of pain and involuntary movements during injection, oculocardiac reflex (OCR), laryngospasm and postoperative shivering were as well registered as the duration of the operation and the time of extubation. Episodes of nausea and vomiting were documented during 24 hours postoperatively. Results: TIVA with Propofol resulted in a decreased heart rate (p = 0.002) and a higher frequency of OCR (p = 0.01) than thiopentone/isoflurane anaesthesia with a higher sensitivity of children younger than 6 years (p = 0.007) in all groups. There were no differences in extubation time between groups. The overall incidence of nausea (p = 0.002) and vomiting (p = 0.007) was lower in group 1 and 2 when compared to group 3 and 4. Conclusion: Propofol as an induction agent of balanced anaesthesia fails to show advantages over thiopentone. During total intravenous anaesthesia propofol increases the risk of bradycardia especially in younger children. However, a significantly lower incidence of postoperative nausea and vomiting after TIVA with propofol and sufentanil, irrespective of N 2O administration, may be an advantage over isoflurane anaesthesia in paediatric patients after strabismus surgery.
A total of 110 patients undergoing elective abdominal hysterectomy were anesthetized in random order with either isoflurane in nitrous oxide and oxygen or isoflurane in air and oxygen. Fentanyl was used as an adjunct to isoflurane in all patients, 0.05 mg every 45 min. No difference was found between the two anesthetic techniques in the incidence of nausea, vomiting, or both during the first 24 hr after operation. The overall incidence was 62 and 67% for air-O2 and N2O-O2 groups, respectively. Patients who had had nausea or vomiting after previous anesthetics had nausea or vomiting significantly more frequently than patients who did not. It is concluded that nitrous oxide does not contribute to the occurrence of nausea or vomiting after isoflurane anesthesia for gynecologic laparotomies.
Mainland and Sutcliffe and Bennett and Hsu have calculated the power of the exact conditional (Fisher Irwin) test for differences between proportions. The authors have performed similar calculations for the comparative trial design with equal margins (A = B = n), and they present tables showing the minimal sample size, n, required in each group to obtain a power of at least 0.50, 0.80, and 0.90 against specified one sided alternatives at the nominal 0.05 and 0.01 significance levels. For completeness, the authors have estimated n from the arc sine approximation whenever the value based on the exact conditional computation exceeded 35.
Nausea and vomiting after anaesthesia and surgery in children remains a major problem. The following survey studies the frequency of postoperative vomiting and relates it to the anaesthestic technique, the surgical procedure, and postoperative analgesia.
During one year, September 1989 until September 1990, 2370 surgical patients requiring anaesthesia were studied prospectively with the following protocol: 1) patient data, surgery and anaesthesia technique; and 2) postoperative follow-up were registered. Outpatients were followed up by telephone.
The overall incidence of vomiting was 19.5 %, which was lower than in other studies.
An increased incidence of vomiting was found in children over 2 years of age, after certain operative procedures, and after general anaesthesia. Furthermore, postoperative opioid administration on the ward increased the risk of vomiting.
Despite the low overall incidence of vomiting in our study, we still found a high frequency after certain surgical procedures. The use of regional anaesthesia, prophylactic antiemetic medication, and the introduction of new anaesthetics, may help to reduce the sometimes high incidence of postoperative nausea and vomiting in paediatric patients.
Postoperative nausea and vomiting (PNV) is a common disorder at the forefront of ambulatory care issues. New antiemetic drugs and improved anesthetic techniques have decreased the incidence of anesthesia-induced PNV. Patient characteristics and surgical factors are now largely responsible for postoperative emesis. Clinicians need to understand these factors to deal effectively with PNV as the use of ambulatory surgery increases. Physicians should consider both prophylactic drug intervention and direct treatment.
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.
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-1. 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.
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).
In the present study, propofol anaesthesia compared to thiopental/isoflurane anaesthesia did not reduce the incidence of vomiting following strabismus surgery in children.