Propofol For Maintenance Of Anesthesia Research Articles

Clinical Effects and Adverse Events Associated With Desflurane Use in Adult Patients Undergoing Supratentorial Craniotomy: A Systematic Review.

Desflurane is an inhalational anesthetic agent with an appealing recovery profile. The present systematic review investigates the clinical effects and adverse events associated with desflurane use during supratentorial craniotomy for brain tumor resection in adults in comparison with other inhalational and intravenous anesthetic agents. A literature search was conducted across the MEDLINE, Library of Congress and LISTA (EBSCO) databases from January 2001 to January 2021. Twelve studies published between 2003 and 2020 were included in this systematic review. Desflurane was compared with either isoflurane, sevoflurane, or propofol for anesthesia maintenance. Brain relaxation scores showed no statistically significant difference between desflurane and the other anesthetic agents. Recovery timepoints, such as time to recovery, time to eye opening, time to extubation, time to follow commands, and time to reach a modified Aldrete score ≥9 were significantly shorter with desflurane in the majority of studies. Systemic hemodynamic variables (mean arterial pressure and heart rate) and cerebral hemodynamics (intracranial pressure and cerebrospinal fluid pressure) were comparable between desflurane and other anesthetic agents in each study. The results of this systematic review demonstrate that desflurane is associated with few adverse events when used for anesthesia maintenance in adult patients undergoing supratentorial brain tumor surgery. Large, prospective, comprehensive studies, utilizing standardized parameter evaluation could provide higher levels of evidence to support these findings.

Prospective randomized double-blind study to evaluate propofol and combination of propofol and sevoflurane as maintenance agents in reducing postoperative nausea and vomiting in female patients undergoing laparoscopic surgery.

Prevention and management of postoperative nausea and vomiting (PONV) is a fundamental part of anesthesia. Using sevoflurane and propofol in combination for maintenance of anesthesia has been found to reduce PONV compared to sevoflurane alone. However, there are limited studies comparing propofol with a combination of propofol and sevoflurane for the incidence of PONV after laparoscopic surgery. The prospective, randomized, double-blind study was planned to compare propofol and combination of propofol and sevoflurane as maintenance agents for the incidence of PONV. Seventy female patients of 18–60 years, of American Society of Anesthesiologists I or II, undergoing laparoscopic surgery were included. Propofol group (n = 35) included induction with propofol and maintenance with propofol infusion, and propofol + sevoflurane group (n = 35) included induction with propofol and maintenance with a combination of propofol infusion and sevoflurane inhalation. The objectives were to find the incidence of PONV and requirement of rescue antiemetic. In the propofol group, 11 patients (33%) experienced PONV and in the propofol + sevoflurane group, PONV was experienced by 12 patients (38.7%) [0.65]. In the propofol group, 11 patients required ondansetron and out of these 11 patients, 2 patients required metoclopramide. In the propofol + sevoflurane group, Ondansetron was required by 12 patients and 3 patients out of these 12 patients required metoclopramide. In the present study, the incidence of PONV was found to be similar in both groups. So, it can be suggested to add sevoflurane in smaller doses to infusion of propofol for maintenance of anesthesia.

Postoperative cognitive dysfunction after sevoflurane or propofol general anaesthesia in combination with spinal anaesthesia for hip arthroplasty.

It is unknown if the type of general anaesthetic used for maintenance of anaesthesia affects the incidence of postoperative cognitive dysfunction (POCD). The aim of this study was to compare the incidence of POCD in patients administered either sevoflurane or propofol for maintenance of anaesthesia during total hip replacement surgery. Following administration of a spinal anaesthetic, patients received either sevoflurane (n=121) or propofol (n=171) at the discretion of the anaesthetist for maintenance of general anaesthesia to maintain the processed electroencephalogram (bispectral index, BIS) under 60. POCD was assessed postoperatively at day 7, three months, and 12 months using a neurocognitive test battery. There was no statistically significant difference between the incidence of POCD at any timepoint with sevoflurane compared to propofol. The mean BIS was significantly lower in the sevoflurane group than in the propofol group (mean BIS 44.3 [standard deviation, SD 7.5] in the sevoflurane group versus 53.7 [SD 8.1] in the propofol group, <i>P</i>=0.0001). However, there was no statistically significant association between intraoperative BIS level and the incidence of POCD at any timepoint. Our results suggest that the incidence of POCD is not strongly influenced by the type of anaesthesia used in elderly patients.

Balancing Tricks and Mini-pigs: Steps along the Road to Propofol

Balancing Tricks and Mini-pigs: Steps along the Road to Propofol

The use of inhaled sevoflurane during operative hysteroscopy is associated with increased glycine absorption compared to intravenous propofol for maintenance of anesthesia

Study ObjectiveTo compare the effects of anesthesia maintenance drugs (inhaled sevoflurane versus intravenous propofol) used in general anesthesia on the absorption of glycine 1.5% solution during hysteroscopy. DesignProspective comparative study. SettingTertiary care university hospital. PatientsOne hundred fifteen women undergoing hysteroscopy. InterventionsWomen were assigned to receive general anesthesia with inhaled sevoflurane (n = 77) or intravenous propofol (n = 38) to maintain anesthesia. MeasurementsThe primary endpoint was clinically relevant glycine 1.5% absorption (>1000 mL), while secondary endpoints were the median of glycine absorption, operative time, complications and the incidence of discontinuation of the hysteroscopic procedure due to excessive glycine 1.5% absorption. Main ResultsMaintenance with sevoflurane produced significantly increased absorption of glycine 1.5% solution compared to intravenous anesthesia (264 vs 202 mL, P = .007). Clinically relevant absorption rates (>1000 mL) were observed in the sevoflurane group (P = .04) while none of the women receiving intravenous anesthesia reached this absorption level. No cases of severe post-operative hyponatremia (Na1+<125 mmol/L) or adverse events derived from glycine 1.5% absorption were reported. No major complications (such as perforations, severe hemorrhage or infection) were presented during the interventions. ConclusionsThe results of the present study show that the use of inhaled sevoflurane is associated with significantly increased glycine 1.5% absorption compared to intravenous propofol for the maintenance of anesthesia. However, further randomized controlled trials are needed to assess the possible mechanisms and risk factors involved in the higher absorption induced by sevoflurane.

Comparison of isoflurane and propofol for maintenance of anesthesia in dogs with intracranial disease undergoing magnetic resonance imaging

ObjectiveTo compare isoflurane and propofol for maintenance of anesthesia and quality of recovery in client-owned dogs with intracranial disease undergoing magnetic resonance imaging (MRI). Study designProspective, randomized, clinical trial. AnimalsTwenty-five client-owned dogs with intracranial pathology, 13 females and 12 males, ages 11 months to 13 years, weighing between 3.0 and 48.0 kg. MethodsEach dog was randomly assigned to receive propofol or isoflurane for maintenance of anesthesia. All dogs were not premedicated, were administered propofol intravenously to effect for induction, intubated and mechanically ventilated to maintain an end-tidal carbon dioxide tension 30–35 mmHg (4.0–4.7 kPa). Temperature and cardiac output were measured pre- and post-MRI. Scores for mentation, neurological status, ease of maintenance, and recovery were obtained pre- and post-anesthesia. Pulse oximetry, end-tidal gases, arterial blood pressure, heart rate (HR) and requirements for dopamine administration to maintain mean arterial pressure (MAP) >60 mmHg were recorded throughout anesthesia. ResultsEnd-tidal isoflurane concentration was 0.73 ± 0.35% and propofol infusion rate was 292 ± 119 μg kg−1 minute−1. Cardiac index was higher, while HR was lower, with propofol than isoflurane in dogs younger than 5 years, but not in older dogs. Dogs maintained with isoflurane were 14.7 times more likely to require dopamine than propofol dogs. Mentation and maintenance scores and temperature were not different. MAP and diastolic arterial pressure were higher in the propofol group. Recovery scores were better with propofol, although times to extubation were similar. Change in neurological score from pre- to post-anesthesia was not different between treatments. ConclusionsDogs maintained with propofol during MRI had higher arterial pressures, decreased requirements for dopamine, and better recovery scores, compared to dogs maintained with isoflurane. Clinical relevancePropofol anesthesia offered cardiovascular and recovery advantages over isoflurane during MRI in dogs with intracranial disease in this study.

Clinical evaluation of total intravenous anaesthesia using xylazine or dexmedetomidine with propofol in surgical management of canine patients

Aim: The aim was to evaluate and compare the clinico-physiological, hemodynamic and hematobiochemical effects in response to different total intravenous anaesthesia techniques using xylazine or dexmedetomidine with propofol in canine patients. Materials and Methods: Under a prospective randomized blinded clinical study, 12 apparently healthy adult dogs (14.27±3.2 kg) divided into two groups (n=6). Animals were administered with xylazine (0.5 mg/kg body weight IV) in X group or, dexmedetomidine (10 μg/kg body weight IV) in D group and propofol (as IV bolus till the induction and continuous IV infusion for maintenance). Clinical reflexes, physiological, hemodynamic parameters, were recorded at 5-min intervals. Blood was collected at zero, 30 and 60 min after initial injection for hematobiochemical evaluation. Statistical analysis was performed using analysis of variance, Duncan's multiple range tests, paired - t-test and Kruskal-Wallis one-way test. Results: Animals showed quicker attenuation of all clinical reflexes in group D. Induction doses of propofol were 3.17±0.21 and 2.72±0.15 mg/kg and rate of infusion of propofol for maintenance of anaesthesia were 0.33±0.02 mg/kg/min and 0.35±0.02 mg/kg/min respectively in group X and D. Recovery was quicker in group D. There were no significant statistical differences in physiological, hemodynamic and hematobiochemical parameters in both the groups. There were no adverse effects after recovery. Conclusion: Both anesthetic protocols provided satisfactory immobilization, but dexmedetomidine-propofol combination may be preferred owing to slightly better degree of basal anaesthesia, lesser doses of propofol required for induction and maintenance of anaesthesia along with a lesser degree of respiratory depression. However, there was no clear preference for either of the protocol, and both appear suitable for canines.

Sa2054 Germ Free Mice Have Normal Epithelial Responses to Serotonin and Acetylcholine in the Proximal Colon

μM propofol, the amplitude was significantly reduced in both distal and proximal colon (p<0.01, n=4). In both the distal and proximal colon, there was change in the frequency of the CMMCs in the presence of propofol. When both ondansetron and L-NNA were added to preparations in the presence of propofol, no differences were observed. In the presence of 1 μMpropofol, fecal pellet motility was significantly reduced compared to control responses (p<0.001, n=5). Conclusions: Propofol significantly increased 5-HT levels in distal colonic but not the proximal mucosa and thus has site specific activity. This may in turn lead to the desensitization of 5-HT3Rs on IPANs. Such effects of propofol can explain the reduced amplitude of CMMCs in the proximal and distal colon and reduced fecal pellet motility. Such findings may provide more insight into intestinal side effects observed in patients utilising propofol for maintenance of anaesthesia and sedation and will provide guidance on approaches to therapeutically managed patients utilising this form of anaesthetic agent.

Comparison of dexmedetomidine versus propofol for maintenance of anesthesia during invasive procedures in pediatric oncology patients: a controlled randomized double-blind study

Background We designed our study to compare the effects of dexmedetomidine infusion versus propofol infusion on perioperative hemodynamics, sedation, pain, and recovery scores for invasive procedures in pediatric oncology patients. Patients and methods Forty children, 6-12 years of age, ASA I or II with hematological cancer, were randomized to receive either dexmedetomidine or propofol infusion during anesthesia for diagnostic or prognostic short-duration procedures. All patients received ketamine 0.5 mg/kg intravenously before the start of the procedure. Increments of ketamine (0.33 mg/kg, intravenously) was given to maintain the sedation score 5-6 using the Ramsay score. Routine vital signs, oxygen saturation, time for induction of sedation, total incremental doses of ketamine, time for spontaneous eye opening after stopping the infusion, recovery excitation score, and pain score were recorded. Results Induction and recovery times were significantly shorter in the propofol/ketamine group. Although there was significant difference in heart rates between the two groups with lower rates for the dexmedetomidine/ketamine group, patients in the dexmedetomidine/ketamine group had significant lesser excitation score and lower pain score than patients in the propofol/ketamine group. Conclusion Dexmedetomidine/ketamine infusion provides hemodynamic stability, lower recovery excitation, and pain scores, although recovery time is prolonged when compared with propofol/ketamine infusion in invasive procedures in pediatric oncology patients. Thus, it represents an alternative sedoanalgesic choice for this population.

Propofol Clearance in Morbidly Obese Children and Adolescents : Influence of Age and Body Size.

Given the alarming increase in obesity among children undergoing surgery, the main aim of this study was to characterize propofol clearance in a cohort of morbidly obese children and adolescents in relation to their age and body weight characteristics. A prospective pharmacokinetic study in morbidly obese children and adolescents undergoing elective surgery was conducted. Serial blood samples were collected and nonlinear mixed-effects modelling using NONMEM® was performed to characterize propofol pharmacokinetics with subsequent evaluation of age and body size descriptors. Twenty obese and morbidly obese children and adolescents with a mean age of 16 years (range 9-18 years), a mean total body weight (TBW) of 125 kg (range 70-184 kg) and a mean body mass index of 46kg/m2 (range 31-63 kg/m2) were available for pharmacokinetic modelling using a two-compartment pharmacokinetic model (n = 294 propofol concentration measurements). Compared with lean body weight and ideal body weight, TBW proved to be the most predictive covariate for clearance [CL (L/min)= 1.70 × (TBW/70)0.8]. Central volume of distribution, peripheral volume and intercompartmental clearance were 45.2 L, 128 L and 1.75 L/min, respectively, with no predictive covariates identifiable. In the population pharmacokinetic model for propofol in morbidly obese children and adolescents, TBW proved to be the most significant determinant for clearance. As a result, it is anticipated that dosage of propofol for maintenance of anaesthesia in morbidly obese children and adolescents should be based on TBW using an allometric function. TRIAL REGISTRATION NUMBER (CLINICALTRIALS.GOV): NCT00948597.

Propofol Clearance in Morbidly Obese Children and Adolescents

Given the alarming increase in obesity among children undergoing surgery, the main aim of this study was to characterize propofol clearance in a cohort of morbidly obese children and adolescents in relation to their age and body weight characteristics. A prospective pharmacokinetic study in morbidly obese children and adolescents undergoing elective surgery was conducted. Serial blood samples were collected and nonlinear mixed-effects modelling using NONMEM(®) was performed to characterize propofol pharmacokinetics with subsequent evaluation of age and body size descriptors. Twenty obese and morbidly obese children and adolescents with a mean age of 16 years (range 9-18 years), a mean total body weight (TBW) of 125 kg (range 70-184 kg) and a mean body mass index of 46 kg/m(2) (range 31-63 kg/m(2)) were available for pharmacokinetic modelling using a two-compartment pharmacokinetic model (n = 294 propofol concentration measurements). Compared with lean body weight and ideal body weight, TBW proved to be the most predictive covariate for clearance [CL (L/min) = 1.70 × (TBW/70)(0.8)]. Central volume of distribution, peripheral volume and intercompartmental clearance were 45.2 L, 128 L and 1.75 L/min, respectively, with no predictive covariates identifiable. In the population pharmacokinetic model for propofol in morbidly obese children and adolescents, TBW proved to be the most significant determinant for clearance. As a result, it is anticipated that dosage of propofol for maintenance of anaesthesia in morbidly obese children and adolescents should be based on TBW using an allometric function.

Ambulatory anesthesia aspects for tonsillectomy and abrasion in children

Tonsillectomy is a very common procedure, but with risks or challenges, both for the surgeon and anesthesiologist. Many places have considerable experience and expertise with this procedure, and a lot of clinical studies are continuously being presented. Most preoperative aspects are covered, including indications, preoperative risk assessment, premedication, anesthetic induction and maintenance, as well as recovery function and side-effects; such as bleeding, agitation, pain, nausea and sleep apnea. Controversies exist as to ambulatory versus in-patient care, laryngeal mask airway versus endotracheal intubation, use of local anesthetic infiltration and use of glucocorticoids. Preoperative evaluation should identify increased bleeding risk, potential airway problems, ongoing infection and symptoms of obstructive sleep apnea.Intravenous propofol is most often used for anesthetic induction, although inhalational sevoflurane is a valid alternative. Laryngeal mask airway or endotracheal tube may both be used safely and effectively; the choice will depend upon the routine and experience of the team. Paracetamol and NSAIDs are useful baseline medication for nonopioid multimodal postoperative pain treatment and prophylaxis. Similar with local anesthesia infiltration and dexamethasone medication, although somewhat more disputed. Dexamethasone is also useful for nausea/vomiting prophylaxis, together with ondansetron and also propofol for anesthesia maintenance.

Desflurane why this choice?

In considering the future role of the volatile anesthetic desflurane (Suprane®) in modern anesthesia practice, it is important to first consider the factors that contribute to a successful anesthetic in this increasingly day surgery orientation. An optimal anesthetic for the new millennium would include the following characteristics. 1.It should have a rapid and smooth onset of action. Efficiency is a particularly important factor in the ambulatory setting [1] 2.There should be a rapid recovery of cognitive functioning without clinically-significant discomfort. Postoperative pain is a major limiting factor in determining when a patient can be discharged home after surgery. 3.The absence of adverse effects such as nausea and vomiting is extremely important as emetic symptoms affect not only recovery times but also the incidence of unanticipated hospital admissions after day-case surgery, and patient satisfaction with their overall anesthetic experience. The low solubility of desflurane contributes to rapid emergence after anesthesia. Compared with sevoflurane, recovery times to eye opening, response to verbal commands, and orientation to person, place, and time have been found to be significantly shorter with desflurane [2-4]. When compared with the rapid, short-acting intravenous anesthetic propofol for induction and maintenance of anesthesia, desflurane displayed more favorable early recovery characteristics and facilitated the fast-tracking process [4,5]. Although patients receiving desflurane are less sedated in the early postoperative period than those receiving propofol, times to ambulation and discharge were similar. Given its favorable early recovery profile, desflurane would appear to be a useful alternative to isoflurane, sevoflurane and propofol for maintenance of anesthesia in a busy practice environment where early discharge is one of the major goals (e.g., cardiovascular, neurosurgery, day-case surgery). In conclusion, desflurane is the maintenance anesthetic agent of choice in a fast-tracking practice environment .

Post-Operative Nausea and Vomiting (PONV) after Thyroid Surgery: A Prospective, Randomized Study Comparing Totally Intravenous versus Inhalational Anesthetics

The incidence of postoperative nausea and vomiting (PONV) after thyroidectomy and the association of Propofol versus Sevoflurane use for anesthesia maintenance were investigated during a randomized, prospective study. One hundred and ninety-eight patients underwent thyroidectomy receiving either Sevoflurane (0.5-1.3% end-tidal) or Propofol (50-200 mg/kg/min) for anesthesia maintenance. All patients received Propofol for induction of anesthesia, Succinylcholine or Vecuronium, Nitrous Oxide, and Fentanyl. Prophylactic antiemetics were not administered. The combined incidence of PONV was 54.4 per cent over the 24-hour postoperative evaluation period. PONV was more common in patients receiving Sevoflurane than Propofol for maintenance of anesthesia (64.6% vs 43.8%). In women (n = 117), the incidence of PONV resulted higher when receiving inhalational Sevoflurane than Propofol for maintenance (70.6% vs 42.4%). However, in men (n = 81), there was no significant difference in PONV between anesthetic regimens (47.4% with Sevoflurane vs 49.6% with Propofol). Patients undergoing thyroid surgery are at high risk for the development of PONV. Propofol for maintenance of anesthesia, although more expensive than Sevoflurane, may reduce the rate of PONV.

A Comparison of Dexmedetomidine-Midazolam With Propofol for Maintenance of Anesthesia in Children Undergoing Magnetic Resonance Imaging

A Comparison of Dexmedetomidine-Midazolam With Propofol for Maintenance of Anesthesia in Children Undergoing Magnetic Resonance Imaging

A Comparison of Dexmedetomidine-Midazolam with Propofol for Maintenance of Anesthesia in Children Undergoing Magnetic Resonance Imaging

Dexmedetomidine is an alpha(2) agonist that is currently being investigated for its suitability to provide anesthesia for children. We compared the pharmacodynamic responses to dexmedetomidine-midazolam and propofol in children anesthetized with sevoflurane undergoing magnetic resonance imaging (MRI). Forty ASA 1 or 2 children, 1-10 yr of age, were randomized to receive either dexmedetomidine-midazolam or propofol for maintenance of anesthesia for MRI after a sevoflurane induction. Dexmedetomidine was administered as an initial loading dose (1 microg/kg) followed by a continuous infusion (0.5 microg x kg(-1) x h(-1)). Midazolam (0.1 mg/kg) was administered i.v. when the infusion commenced. Propofol was administered as a continuous infusion (250-300 microg x kg(-1) x min(-1)). Recovery times and hemodynamic responses were recorded by one nurse who was blinded to the treatments. We found that the times to fully recover and to discharge from the ambulatory unit after dexmedetomidine administration were significantly greater (by 15 min) than those after propofol. Analysis of variance demonstrated that heart rate was slower and systolic blood pressure was greater with dexmedetomidine than propofol. Respiratory indices for the two treatments were similar. During recovery, hemodynamic responses were similar. Cardiorespiratory indices during anesthesia and recovery remained within normal limits for the children's ages. No adverse events were recorded. Dexmedetomidine-midazolam provides adequate anesthesia for MRI although recovery is prolonged when compared with propofol. Heart rate was slower and systolic blood pressure was greater with dexmedetomidine when compared with propofol. Respiratory indices were similar for the two treatments.

Rocuronium duration of action under sevoflurane, desflurane or propofol anaesthesia

We conducted a prospective randomized study to evaluate whether the duration of action of a single bolus dose of rocuronium is influenced by maintenance of anaesthesia with sevoflurane, desflurane or propofol infusion. Fifty-seven ASA I-II patients undergoing elective abdominal surgery were enrolled in this study. Anaesthesia was induced with thiopental 3-5 mg kg(-1) or propofol 2.5 mg kg(-1) and fentanyl 5 microg kg(-1) and tracheal intubation was facilitated with rocuronium 0.9 mg kg(-1). Thereafter patients were randomly allocated to three different groups to receive sevoflurane, desflurane or propofol for maintenance of anaesthesia. Recovery of neuromuscular function was monitored by single twitch stimulation of the ulnar nerve and by recording the adductor pollicis response using accelerometry. Intergroup recovery times to 5% of control value of single twitch were analysed using analysis of variance with Bonferroni correction. The mean (95% confidence interval) recovery time to 5% of control value of single twitch during desflurane anaesthesia was 90.18 (86.11-94.25) min. Significantly shorter recovery times were observed during sevoflurane or propofol anaesthesia, 58.86 (54.73-62.99) min and 51.11 (45.47-56.74) min, respectively (P < 0.001). There were also significant differences in the recovery time between groups receiving desflurane vs. sevoflurane (P < 0.001) and desflurane vs. propofol (P < 0.001). Desflurane anaesthesia significantly prolongs the duration of action of rocuronium at 0.9 mg kg(-1) single bolus dose, compared to sevoflurane or propofol anaesthesia maintenance regimens.

Anaesthesia for magnetoencephalography in children with intractable seizures.

Magnetoencephalography (MEG), a noninvasive technique for evaluation of epileptic patients, records magnetic fields during neuronal electrical activity within the brain. Anaesthesia experience for MEG has not yet been reported. We retrospectively reviewed records of 48 paediatric patients undergoing MEG under anaesthesia. Thirty-one patients (nonprotocol group) were managed according to the anaesthesiologist's discretion. Premedication included oral midazolam, chloral hydrate or fentanyl oralet, intravenous midazolam or inhalational anaesthesia with sevoflurane. Anaesthesia was maintained with propofol, midazolam, fentanyl, alone or in combination. A subsequent protocol group (17 patients) received chloral hydrate as premedication and propofol for maintenance of anaesthesia. There was an overall 25% failure of interictal activity and localization on the MEG scan. In the nonprotocol group, 11 scans failed (35.5%). Of these, eight (72.7%) received midazolam orally. Only one failure (5.8%) was recorded in the protocol group in a patient who received chloral hydrate as sedation supplemented by sevoflurane. In our experience, midazolam premedication resulted in a high MEG failure rate (73%). Chloral hydrate premedication and propofol maintenance resulted in a lower incidence of MEG failure (5.8%). General anaesthesia with a continuous infusion of propofol or sevoflurane appears acceptable, although, lighter levels of anaesthesia might be required to avoid interference with interictal activity of the brain.

Propofol in an Emulsion of Long- and Medium-Chain Triglycerides: The Effect on Pain

Propofol in an Emulsion of Long- and Medium-Chain Triglycerides: The Effect on Pain

Target controlled infusions

Target controlled infusion (TCI) combines a real-time pharmacokinetic model with an infusion pump and allows the administration and maintenance of a constant blood concentration of drug. TCI also allows alterations in the blood concentration to be made rapidly and easily. A TCI system for propofol, the ‘Diprifusor’, is now available and has greatly simplified the administration of propofol for maintenance of anaesthesia. TCI systems for other drugs exist, such as alfentanil and remifentanil, but are not yet commercially available. TCI propofol for maintenance of anaesthesia offers several benefits compared to volatile agents, including rapid recovery with a low incidence of nausea and vomiting. This review explores the development of TCI and discusses its advantages and disadvantages.