General purpose propofol target-controlled infusion using the marsh model with adjusted weight input

We report a simple method for adjusting the weight input of the Marsh target-controlled infusion (TCI) model such that the resulting infusion regime closely mimics the behaviour of the Eleveld model, thereby making the Marsh model more precise for patients at the extremes of age and body mass index. To assess the performance of our method, we simulated 2768 subjects with diverse combinations of age, weight, height and sex undergoing a hypothetical four-hour propofol TCI using both the Marsh model with our weight adjustment and the Eleveld model. The weight adjusted Marsh model produced infusion regimes and corresponding effect site concentrations closely mimicking that of the Eleveld model at all time points, with median and maximum absolute performance errors less than 8.1% and 20.3%, respectively, across the entire cohort. Our weight adjustment method is a simple and robust way of improving the precision of the Marsh model in patients at extremes of age and body mass index, until general purpose TCI models for propofol, such as the Eleveld model, become more widely available in commercial infusion pumps.

Evaluating inter-individual variability captured by the Eleveld pharmacokinetics model

Inter-individual variability in Pharmacokinetic (PK) and Pharmacodynamic (PD) models significantly affects the accuracy of Target Controlled Infusion and closed-loop control of anesthesia. We hypothesize that the novel Eleveld PK model captures more inter-individual variability relevant to both open-loop and closed-loop control design, resulting in reduced variability in PD models identified using the Eleveld PK model's plasma prediction compared to the Schuttler or Schnider PK model. We used a dataset of propofol infusion rates and Depth of Hypnosis measurements across three demographic groups: elderly, obese, and adult. PD models are identified based on plasma concentration prediction using three PK models (Schuttler, Schnider, and Eleveld). Validation methods are presented to confirm acceptable predictive performance and comparable PK-PD model variability within each demographic group. To test our hypothesis, we compared coefficient variations in step responses for open-loop control and multiplicative uncertainty of PD model sets for closed-loop control. Validated PKPD models using the Schuttler and Schnider PK model showed no significant differences in predictive response and multiplicative uncertainty compared to the Eleveld PK model. The coefficient variations in step responses of PD model sets and the frequency ranges, corresponding to uncertainty below one, were comparable for all three PK models. The comparison of the accumulated coefficient of variation in the step-response and the uncertainty of the PD model sets indicated that the Eleveld PK model does not offer any advantage for the design of open-loop or closed-loop control of anesthesia.

Does Propofol Effect Site (Brain) Concentration Predicted by Target-Controlled Infusion Correlate with Propofol Measured in the Brain? An Exploratory Study in Neurosurgical Patients

BACKGROUND

Total intravenous anesthesia with propofol can be administered by target-controlled infusion pumps, which work on the principles of pharmacokinetic modeling. While designing this model, neurosurgical patients were excluded as the surgical site and drug action site remained the same (brain). Whether the predicted set propofol concentration and the actual brain site concentration correlate, especially in neurosurgical patients with impaired blood-brain barrier (BBB), is still unknown. In this study we compared the set propofol effect-site concentration in the target-controlled infusion pump with actual brain concentration measured by sampling the cerebrospinal fluid (CSF).

METHODS

Consecutive adult neurosurgical patients requiring propofol infusion intraoperatively were recruited. Blood and CSF samples were collected simultaneously when patients received propofol infusion at 2 different target effect-site concentrations-2 and 4 ug/mL. To study BBB integrity, CSF-to-blood albumin ratio and imaging findings were compared. The propofol level in the CSF was compared with set concentration using the Wilcoxon signed-rank test.

RESULTS

Fifty patients were recruited, and the data were analyzed from 43 patients. There was no correlation between propofol concentration set in TCI and propofol concentration measured in blood and CSF. Though imaging findings were suggestive of BBB disruption in 37/43 patients, the mean (±standard deviation) CSF-to-serum albumin ratio was 0.0028 ± 0.002, suggesting intact BBB integrity (ratio >0.3 was considered as disrupted BBB).

CONCLUSIONS

CSF propofol level did not correlate with set concentration in spite of acceptable clinical anesthetic effect. Also, the CSF-to-blood albumin measurement did not provide information on the BBB integrity.

Effect-site concentrations of remifentanil for smooth emergence from combined epidural-general anesthesia or general anesthesia in patients using video double-lumen tube: A randomized trial

Objective

The present study aimed to determine the effect-site concentration of remifentanil of 90% (EC90) for smooth emergence in patients with a video DLT (VDLT) under sevoflurane-maintained general anesthesia and to investigate whether the EC90 was affected by epidural anesthesia.

Methods

One hundred and twenty patients who underwent video-assisted thoracic surgery (VATS) were enrolled. Patients received either general anesthesia combined with epidural anesthesia (PEA group, n = 60) or general anesthesia (GA group, n = 60). The primary outcome was the EC90 for smooth emergence in both groups. The secondary outcomes were intraoperative emergence, smooth emergence, recovery, and hemodynamic profiles in both groups.

Result

The EC90 values for smooth emergence in patients using VDLT were 3.5 ng/ml (95% confidence interval [CI], 3.3-4.4 ng/ml) in the PEA group and 2.7 ng/ml (95% CI, 2.5-3.2 ng/ml) in the GA group. The total amount of remifentanil infusion during emergency was significantly higher in the PEA group (164.6 ± 47.9 μg) than in the GA group (127.1 ± 30.4 μg) (P < 0.001). The number of patients who experienced hypotension during emergency in the PEA group was higher than that in the GA group (46.7% versus 13.3%, P < 0.001).

Conclusion

The EC90 of remifentanil for smooth emergence in patients with VDLT under general anesthesia combined with epidural anesthesia (3.5 ng/ml) was higher than that under general anesthesia (2.7 ng/ml).

Trial registration

Chinese Clinical Trial Registry, ChiCTR2100054230.

Efficacy and safety of propofol target-controlled infusion combined with butorphanol for sedated colonoscopy

BACKGROUND

Propofol is a short-acting, rapid-recovering anesthetic widely used in sedated colonoscopy for the early detection, diagnosis and treatment of colon diseases. However, the use of propofol alone may require high doses to achieve the induction of anesthesia in sedated colonoscopy, which has been associated with anesthesia-related adverse events (AEs), including hypoxemia, sinus bradycardia, and hypotension. Therefore, propofol co-administrated with other anesthetics has been proposed to reduce the required dose of propofol, enhance the efficacy, and improve the satisfaction of patients receiving colonoscopy under sedation.

AIM

To evaluate the efficacy and safety of propofol target-controlled infusion (TCI) in combination with butorphanol for sedation during colonoscopy.

METHODS

In this controlled clinical trial, a total of 106 patients, who were scheduled for sedated colonoscopy, were prospectively recruited and assigned into three groups to receive different doses of butorphanol before propofol TCI: Low-dose butorphanol group (5 μg/kg, group B1), high-dose butorphanol group (10 μg/kg, group B2), and control group (normal saline, group C). Anesthesia was achieved by propofol TCI. The primary outcome was the median effective concentration (EC50) of propofol TCI, which was measured using the up-and-down sequential method. The secondary outcomes included AEs in perianesthesia and recovery characteristics.

RESULTS

The EC50 of propofol for TCI was 3.03 μg/mL [95% confidence interval (CI): 2.83-3.23 μg/mL] in group B2, 3.41 μg/mL (95%CI: 3.20-3.62 μg/mL) in group B1, and 4.05 μg/mL (95%CI: 3.78-4.34 μg/mL) in group C. The amount of propofol necessary for anesthesia was 132 mg [interquartile range (IQR), 125-144.75 mg] in group B2 and 142 mg (IQR, 135-154 mg) in group B1. Furthermore, the awakening concentration was 1.1 μg/mL (IQR, 0.9-1.2 μg/mL) in group B2 and 1.2 μg/mL (IQR, 1.025-1.5 μg/mL) in group B1. Notably, the propofol TCI plus butorphanol groups (groups B1 and B2) had a lower incidence of anesthesia AEs, when compared to group C. Furthermore, no significant differences were observed in the rates of AEs in perianesthesia, including hypoxemia, sinus bradycardia, hypotension, nausea and vomiting, and vertigo, among group C, group B1 and group B2.

CONCLUSION

The combined use with butorphanol reduces the EC50 of propofol TCI for anesthesia. The decrease in propofol might contribute to the reduced anesthesia-related AEs in patients undergoing sedated colonoscopy.

Comparison of hemodynamics during induction of general anesthesia with remimazolam and target-controlled propofol in middle-aged and elderly patients: a single-center, randomized, controlled trial

BACKGROUND

Remimazolam confers a lower risk of hypotension than propofol. However, no studies have compared the efficacy of remimazolam and propofol administered using target-controlled infusion (TCI). This study aimed to investigate hemodynamic effects of remimazolam and target-controlled propofol in middle-aged and elderly patients during the induction of anesthesia.

METHODS

Forty adults aged 45-80 years with the American Society of Anesthesiologists Physical Status 1-2 were randomly assigned to remimazolam or propofol group (n = 20 each). Patients received either remimazolam (12 mg/kg/h) or propofol (3 μg/mL, TCI), along with remifentanil for inducing anesthesia. We recorded the blood pressure, heart rate (HR), and estimated continuous cardiac output (esCCO) using the pulse wave transit time. The primary outcome was the maximum change in mean arterial pressure (MAP) after induction. Secondary outcomes included changes in HR, cardiac output (CO), and stroke volume (SV).

RESULTS

MAP decreased after induction of anesthesia in both groups, without significant differences between the groups (- 41.1 [16.4] mmHg and - 42.8 [10.8] mmHg in remimazolam and propofol groups, respectively; mean difference: 1.7 [95% confidence interval: - 8.2 to 4.9]; p = 0.613). Furthermore, HR, CO, and SV decreased after induction in both groups, without significant differences between the groups. Remimazolam group had significantly shorter time until loss of consciousness than propofol group (1.7 [0.7] min and 3.5 [1.7] min, respectively; p < 0.001). However, MAP, HR, CO, and SV were not significantly different between the groups despite adjusting time until loss of consciousness as a covariate. Seven (35%) and 11 (55%) patients in the remimazolam and propofol groups, respectively, experienced hypotension (MAP < 65 mmHg over 2.5 min), without significant differences between the groups (p = 0.341).

CONCLUSIONS

Hemodynamics were not significantly different between remimazolam and target-controlled propofol groups during induction of anesthesia. Thus, not only the choice but also the dose and usage of anesthetics are important for hemodynamic stability while inducing anesthesia. Clinicians should monitor hypotension while inducing anesthesia with remimazolam as well as propofol.

TRIAL REGISTRATION

UMIN-CTR (UMIN000045612).

Efficacy and safety of remifentanil for endoscopic ultrasound-guided tissue acquisition: a single center retrospective study

BACKGROUND

Remifentanil is a rapid onset and rapid recovery opioid. The combination of remifentanil and propofol for deep sedation decreases the incidents of movement, cough, and hiccup. We evaluated the efficacy and safety of remifentanil during endoscopic ultrasound-guided tissue acquisition.

METHODS

We retrospectively reviewed patients in whom endoscopic ultrasound-guided tissue acquisition was performed for solid mass lesions of the upper gastrointestinal tract and adjacent organs. All patients were premedicated with midazolam (2 mg), and target-controlled infusion of propofol, opioid, and Bispectral Index (BIS) monitoring were administered as necessary to maintain moderate-to-deep sedation. The opioids used were a bolus of alfentanil or remifentanil infusion. The discharge time, consumption of propofol and opioid, adverse events, diagnostic accuracy, and sensitivity and specificity for malignancy, were compared.

RESULTS

Tissue acquisition was achieved in 123 patients (alfentanil group, n = 64; remifentanil group, n = 59). The discharge time of the remifentanil group (16.5 ± 3.2 min) was significantly shorter than that of the alfentanil group (19.0 ± 4.9 min, P = 0.001). The consumption of propofol, adverse events, diagnostic accuracy, sensitivity, and specificity for malignancy in the alfentanil group were not significantly different from those in the remifentanil group.

CONCLUSIONS

Use of alfentanil or remifentanil for target-controlled infusion of propofol-BIS monitoring can provide good sedative and diagnostic quality for endoscopic ultrasound-guided tissue acquisition. However, remifentanil resulted in faster recovery than alfentanil.

Effect of different propofol infusion methods during ultrasound-guided percutaneous microwave ablation on brain functional state indexes and circulatory function in patients with liver cancer

BACKGROUND

During percutaneous microwave coagulation therapy (PMCT), patients under local anesthesia are prone to body movement because they cannot tolerate high tempera-ture stimulation, which results in microwave needle displacement, so intravenous general anesthesia is required. Propofol is a short-acting intravenous anesthetic widely used in clinical practice. It has the characteristics of fast action, large distribution volume, and high clearance rate, and is widely used for induction and maintenance of general anesthesia.

AIM

To investigate the effect of different propofol infusion methods during ultrasound-guided PMCT on the cerebral functional status indexes and circulatory function in patients with liver cancer.

METHODS

A total of 74 patients with liver cancer treated at our hospital from January 2017 to January 2021 were selected as the research subjects, and they were randomly divided into either a target-controlled infusion group (group A, n = 37) or an intermittent injection group (group B, n = 37). The circulatory function [heart rate (HR) and mean arterial pressure (MAP)] between the two groups was compared before operation (T0), at the beginning of the operation (T1), 5 min after the beginning of the operation (T2), when the temperature of the cancerous focus reached 90 °C (T3), and when awaking (T4) after the operation. Brain function state [wavelet index (WLi), anxiety index (ANXi), and comfort index (CFi)], propofol dosage, recovery time from anesthesia, postoperative pain visual analogue scale (VAS) score, cognition mini-mental state examination (MMSE) score, and incidence of adverse reactions were also compared between the two groups.

RESULTS

At T1, T2, and T3, the MAP and HR of group A were significantly higher than those of group B (P < 0.05). At T1, T2, and T3, WLi, ANXi, and CFi of group A were significantly lower than those of group B (P < 0.05). Propofol dosage did not differ significantly between the two groups (P > 0.05). The recovery time from anesthesia in group A was significantly longer than that in group B (P < 0.05); VAS scores and differences at 30 min and 3 h after operation in group A were significantly lower than those in group B (P < 0.05). Compared with the score at 1 d before operation, MMSE scores at 1 and 2 d after operation were significantly decreased. MMSE score of group A was significantly higher than that of group B on the first day after operation (P < 0.05), though the difference in MMSE score between the two groups on the second day after operation was not statistically significant (P > 0.05). There was no respiratory depression in either group, and the incidence of body movement in group A was significantly lower than that in group B (P < 0.05).

CONCLUSION

During PMCT, intermittent intravenous injection and target-controlled infusion of propofol are both safe and effective for liver cancer patients, but the latter has relatively little effect on the brain function of patients, better analgesic effect and maintenance of body circulation stability, less body movement during the operation, and higher safety.

Generic rocuronium reduces withdrawal movements compared to original rocuronium under target-controlled infusion induction with propofol

PURPOSE

Rocuronium-induced injection pain often causes withdrawal movements leading to accidental disruption of indwelling needles. Generic rocuronium (Maruishi Pharmaceutical Co., Ltd, Osaka, Japan) with a novel solution has been reported to reduce the injection pain compared to original rocuronium [Esmeron^® (Eslax^®), MSD Co. Ltd, Tokyo, Japan], however, no reports have compared the injection pain under sedation with propofol, the most frequently used general anesthetic. This study was carried out to compare the injection pain caused by generic rocuronium and that caused by original rocuronium in patients anesthetized by propofol with a target-controlled infusion system.

METHODS

Forty patients were randomly assigned to two groups in this single-center, prospective, randomized, double-blind study. One group was administered generic rocuronium after sedation with propofol with a target-controlled infusion system. The other group was administered original rocuronium after anesthesia with propofol. Patient's withdrawal movements were assessed with the scale. The primary outcome was the total incidence of movement after administration of rocuronium. Secondary outcome was the incidence of moderate or severe movement after administration of rocuronium.

RESULTS

The total incidence of movement after administration of generic rocuronium (11%) was significantly lower than that after the administration of original rocuronium (79%) (p < 0.01). The incidence of moderate or severe movement after administration of generic rocuronium (0%) was significantly lower than that after the administration of original rocuronium (53%) (p < 0.01).

CONCLUSION

Generic rocuronium was considered more suitable than the original rocuronium for induction of anesthesia by propofol performed with a target-controlled infusion system.

Acceptability of intravenous propofol sedation for adolescent dental care

PURPOSE

Propofol is an intravenous anaesthetic agent commonly utilised in general anaesthesia, however in sub-anaesthetic concentrations can be utilised to provide sedation through automated dosing of target-controlled infusion (TCI). TCI has been shown to provide accurate and stable predicted plasma and effect-site concentrations of propofol. A four-part mixed-method prospective study was undertaken to evaluate the safety and patient acceptability of intravenous propofol sedation in adolescent patients requiring dental care. There is a paucity in the literature on patient-reported outcomes and patient safety in the management of adolescent patients for dental treatment.

METHODS

Demographics were recorded including age, gender, ASA Classification and Children's Fear Survey Schedule-Dental Subscale (CFSS-DS) completed pre-operatively. Behaviour ratings of the Frankl and Houpt scales were recorded followed by post-operative questionnaire and telephone consultation. Consultation was completed following the procedure to determine patient satisfaction, memory of the procedure and any reported side effects of treatment. Qualitative thematic analysis was utilised.

RESULTS

55 patients were recruited for the study, of which 49 (mean age 14.67 years) completed the sedation study and were treated safely with no post-operative complications. The mean lowest oxygen saturation was 98.12% SpO₂ (SD 2.6). Thematic analysis demonstrated positive patient-reported outcomes to IV sedation.

CONCLUSION

Propofol TCI sedation is an effective treatment modality for the management of dentally anxious adolescents as a safe alternative to general anaesthesia, allowing the opportunity for increased provision of treatment per visit on those patients with a high dental need. Further randomised controlled trials comparing propofol TCI to other pharmacological managements are required.

Effect-site concentration of remifentanil for preventing propofol injection pain during induction of balanced anesthesia

Background

Despite various strategies designed for preventing pain from propofol injection, it is still common and distressing to the patients. The purpose of the present study was to investigate the adequate effect-site concentration (Ce) of remifentanil to prevent pain due to propofol injection.

Methods

A total of 160 adults scheduled for elective surgery were randomly assigned to one of four groups receiving normal saline (group S) or remifentanil at a Ce of 2 (group R2), 3 (group R3), or 4 ng/ml (group R4), administered via target-controlled infusion, followed by the injection of 2 mg/kg of propofol (delivered with 1% lipid propofol). The severity and incidence of injection pain were assessed on a four-point scale.

Results

The incidence of propofol injection pain was significantly lower in group R2, R3, or R4 than in group S (30%, 5%, or 2.5% vs. 70%, respectively). Moreover, the intensity of the pain was lesser in group R2, R3, or R4 than in group S. However, the incidence or severity of injection was not different between groups R3 and R4.

Conclusions

During the induction of balanced anesthesia using propofol injection, pretreatment with remifentanil at a target Ce of 3 ng/ml effectively reduced propofol injection pain in adults.

The predictive performance of propofol target-controlled infusion during robotic-assisted laparoscopic prostatectomy with CO2 pneumoperitoneum in the head-down position

PURPOSE

Propofol clearance can be reduced when cardiac output (CO) is decreased. This clearance reduction may alter the pharmacokinetics of propofol and worsen the predictive performance of target-controlled infusion (TCI) of propofol. The head-down position (HDP) and CO₂ pneumoperitoneum, which are required for robotic-assisted laparoscopic prostatectomy (RALP), may cause changes in CO. We investigated the predictive performance of propofol TCI during CO₂ pneumoperitoneum in patients who underwent RALP in the HDP.

METHODS

Fifteen male patients received propofol TCI using the Diprifusor model. Propofol concentrations were measured at seven time points: (T1) 15 min after anesthesia induction; (T2) before the insufflation; (T3, T4, and T5) 15, 60, and 90 min, respectively, after insufflation in the HDP; (T6) before the release of pneumoperitoneum in the HDP; and (T7) 15 min after the release of pneumoperitoneum in the supine position. Cardiac index (CI) was assessed using an arterial pulse contour CO monitor. The predictive performance of propofol TCI was evaluated by calculating the performance errors (PE) in propofol concentrations for each data point. The relationship between CI and PE was examined. Median PE (MDPE) and median absolute PE (MDAPE) were calculated as measures of bias and accuracy, respectively.

RESULTS

A total of 104 blood samples were analyzed. There was significantly negative correlation between CI and PE. The predictive performance of propofol TCI during pneumoperitoneum in the HDP was acceptable (MDPE = - 1.5% and MDAPE = 18.8%).

CONCLUSION

The predictive performance of propofol TCI during RALP with CO₂ pneumoperitoneum in the HDP was acceptable.

A study protocol for a feasibility study: Propofol Target-Controlled Infusion in Emergency Department Sedation (ProTEDS)-a multi-centre feasibility study protocol

Background

Procedural sedation is a core skill of the emergency physician. Bolus administration of propofol is widely utilised in UK emergency departments to provide procedural sedation. Bolus administration of propofol, titrated to an endpoint of sedation, has a rapid effect but can easily result in apnoea and loss of airway patency. The use of a target-controlled infusion of propofol allows for controlled titration to an effect site concentration and may reduce the rate of adverse incidents. Target-controlled infusion of propofol is not currently used in emergency departments.The primary aim of this feasibility study is to ensure that propofol target-controlled infusion (TCI) is acceptable to the patient and that recruitment rates are adequate to power a randomised controlled trial comparing propofol target-controlled infusion versus bolus administration.

Methods

This study will recruit in four emergency departments in Scotland, UK. Patients aged 18-65 years with anterior shoulder dislocation, weighing ≥ 50 kg and fasted ≥ 90 min, will be screened. Recruited patients will undergo emergency reduction of a dislocated shoulder facilitated by procedural sedation utilising TCI of propofol.The widespread adoption of TCI propofol by emergency departments will require evidence that it is safe, potentially effective, patient centred and a timely method of providing procedural sedation. The primary endpoint will be acceptability measured by patient satisfaction. The secondary endpoints will include incidence and severity of adverse events, number of shoulder reduction attempts, nursing opinion of patient experience, patient's reported pain score and time from commencement of TCI propofol sedation to desired sedation level.The study will be open for recruitment from April 2017 to December 2018.

Discussion

If the study demonstrates patient acceptability with adequate recruitment, we will be in a position to determine the feasibility of progression to a randomised controlled clinical trial of TCI compared to bolus administration of propofol.

Trial registration

ClinicalTrials.gov Identifier: NCT03442803. Registered retrospectively on 22 February 2018.

Effect of sex and polymorphisms of CYP2B6 and UGT1A9 on the difference between the target-controlled infusion predicted and measured plasma propofol concentration

Introduction

To examine whether sex and polymorphisms of cytochrome P450 (CYP) 2B6 and UDP-glucuronosyltransferase (UGT) 1A9 affect the difference between predicted and measured plasma propofol concentration during continuous infusion by target-controlled infusion.

Results

Blood samples of 69 patients (48 men and 21 women) were obtained at 4 h after initial propofol infusion. Percentage performance error (PE) was calculated to assess the difference between measured and predicted propofol concentration. Regression coefficients (β) and 95% confidence intervals (CI) of sex and the polymorphisms of CYP2B6 and UGT1A9 for PE were, separately and mutually, estimated with linear regression. Covariates included age and body mass index in the minimal adjusted model, and additionally included clinical factors (mean blood pressure, heart rate, volume of intravenous fluid, surgical site, surgical position, and pneumoperitoneum) in the full adjusted model. PE was higher in men than in women (28.7% versus 10.5%, p = 0.015). Female sex was inversely associated with PE: the minimal adjusted β = − 8.84 (95% CI, − 16.26 to − 1.43); however, the fully adjusted β with clinical factors became not significant. The average of PE did not differ between polymorphisms of CYP2B6 and UGT1A9, and β of CYP2B6 516G>T polymorphisms mutually adjusted with female sex was not significant. Mean blood pressure, heart rate, and volume of intravenous fluid were independently associated with PE in the full adjusted model.

Conclusions

Under 4 h anesthesia with propofol target-controlled infusion in our population, sex differences appeared to exist in the propofol concentration, which might be largely mediated by clinical factors, such as hemodynamic status.

Trial registration

UMIN-CTR UMIN000009015, Registered 1 October 2012

Electronic supplementary material

The online version of this article (10.1186/s40981-018-0196-8) contains supplementary material, which is available to authorized users.

Safety of Target-Controlled Propofol Infusion by Gastroenterologists in Patients Undergoing Endoscopic Resection

BACKGROUND

A target-controlled infusion (TCI) of a propofol system uses a pharmacokinetic model to achieve and maintain a selected target blood propofol concentration. The aim of this study was to assess whether the propofol TCI system could be safely used by gastroenterologists in patients undergoing endoscopic resection including endoscopic submucosal dissection (ESD) and endoscopic mucosal resection (EMR) compared with a manually controlled infusion (MCI) system.

METHODS

A total of 431 patients undergoing therapeutic endoscopy (178 ESD and 253 EMR) were consecutively included from November 2011 to August 2014. The patients were divided into the MCI (271) and TCI (160) propofol infusion groups. We compared adverse event rates in MCI and TCI groups and assessed independent risk factors for adverse events.

RESULTS

The total sedation-related adverse event rate was 5.8 % (25/431). Most of the events were minor, and the rate of major events was 0.5 % (2/431). There was no significant difference in adverse event rate between the MCI and TCI groups [5.5 % (15/271) vs. 6.3 % (10/160); P = 0.759]. In univariate analysis, the propofol infusion time was significantly associated with adverse events (94.88 vs. 59.45 min, P = 0.017). In the multivariate analysis, there were no significant factors associated with adverse events. TCI was not an independent risk factor for adverse events despite the fact that the TCI had a longer duration of infusion and higher total infusion dose (95 % CI, 0.343-2.216; P = 0.773).

CONCLUSIONS

TCI of propofol by gastroenterologists may provide safe sedation in patients undergoing ESD and EMR under careful respiratory monitoring.

Asleep-awake-asleep regimen for epilepsy surgery: a prospective study of target-controlled infusion versus manually controlled infusion technique

BACKGROUND

Asleep-awake-asleep (AAA) protocol for epilepsy surgery is a unique opportunity to accurately map epilepsy foci involved in motor and eloquent areas, allowing the operator to optimize the resection. Two different application modes of intravenous anesthesia for AAA craniotomies are widely used: infusion by means of target-controlled infusion (TCI) and traditional manually-controlled infusion (MCI). We conducted this study to examine whether intravenous anesthesia using the TCI system with propofol and remifentanil would be a more effective method than MCI in AAA epilepsy surgery.

METHODS

This prospective and single center study compared patients undergoing either TCI or MCI techniques for functional AAA epilepsy surgery. 35 cases used TCI including TCI-E (resection of epileptogenic foci in an eloquent area, n = 18) and TCI-M (resection of epileptogenic foci in a motor area, n = 17). Thirty-six cases used MCI including MCI-E (epileptogenic foci in an eloquent area, n = 16) and MCI-M (epileptogenic foci in a motor area, n = 20). Bispectral index value and hemodynamic profiles at different time points during the awake phase were recorded along with time for awakening and the occurrences of adverse events.

RESULTS

The TCI technique significantly shortened intraoperative awakening times during the third phase, TCI-E vs MCI-E 12.82 min ± 6.93 vs 29.9 min ± 9.04 (P = .000) and TCI-M vs MCI-M 16.8 min ± 5.19 vs 30.91 min ± 15.32 (P = .010). During the awake phase, the highest bispectral index score values appeared in the TCI-E group at all-time points. Mean arterial pressure and heart rate were more stable in the TCI-E group compared with the MCI-E group during the awake phase. Tachycardia and hypertension were most common in the MCI-E group (52.9% and 29.4%, P = .001 and P = .064).

CONCLUSION

We found the superiority of TCI, which is faster intraoperative awakening and better hemodynamics along with secure airway management conditions. It is suggested that the TCI technique may be a feasible and effective technique and it might be a viable replacement of the MCI technique for AAA epilepsy surgery.

The administration of high-dose propofol sedation with manual and target-controlled infusion in children undergoing radiation therapy: a 7-year clinical investigation

Background

Radiation therapy requires the patient to remain immobile for a long time, which is challenging in children. This study therefore aimed to determine the adequate target concentration and dosage of propofol in target-controlled infusion (TCI) and manual infusion (MI) in children requiring sedation for proton radiation therapy. Our hypothesis is that the adequate dose of propofol sedation required for proton radiation therapy in pediatric patients was larger than that seen in previous studies.

Methods

We retrospectively analyzed the medical records of Korean children who received proton therapy under propofol sedation. The average target concentration at induction and during maintenance with TCI and the dose with MI were analyzed as primary outcomes.

Results

A total of 1296 procedures in 54 children were analyzed (TCI group, 26; MI group, 28). The median bolus dose of propofol in the MI group was 2.6 (2.2–3.0) mg/kg, while the pump speed was 17.0 (13.6–25.8) mg/kg/h. The median target concentration of propofol in the TCI group was 5.3 (4.4–5.7) mcg/mL at induction and 4.2 (3.1–5.1) mcg/mL during maintenance. There were no cases of life-threatening complications in either group over 7 years. There were six cases of transient desaturation, which were managed by using the jaw thrust maneuver.

Conclusions

Compared with those in previous studies, the target concentration of propofol with TCI and the propofol dose with MI required for adequate sedation in children undergoing proton radiation therapy were larger in the present study. Despite concerns regarding overdosage, the complications were managed well. However, safe and adequate sedation for proton radiation therapy remains a challenge. The development of monitoring tools to evaluate the depth of sedation is necessary to adjust the propofol dose and sedation level.

Propofol target-controlled infusion for sedated gastrointestinal endoscopy: A comparison of propofol alone versus propofol-fentanyl-midazolam. Kaohsiung J Med Sci. 2015;31:580-584. [PMID: 26678938 DOI: 10.1016/j.kjms.2015.09.004]

Gastrointestinal (GI) endoscopy is the major technique for diagnosis of GI disease and treatment. Various sedation and analgesia regimens such as midazolam, fentanyl, and propofol can be used during GI endoscopy. The purpose of the study was to compare propofol alone and propofol combination with midazolam and fentanyl in moderate sedation for GI endoscopy. One hundred patients undergoing GI endoscopy were enrolled in this study. All patients received a propofol target-controlled infusion (TCI) to maintain sedation during the procedure. Patients were randomly allocated into either Group P (propofol TCI alone) or Group C (combination of propofol TCI plus midazolam and fentanyl). Dermographic data, anesthetic parameters (sedation regimen, blood pressure, heart rate, and oxygen saturation), procedure parameters (procedure time, colonoscopy, or panendoscopy), propofol consumption, and adverse events (hypoxia, hypotension, and bradycardia) were all recorded. Postprocedural records included recovery time, postoperative adverse events (nausea, vomiting, dizziness, recall, and pain) and satisfaction. The average propofol consumption was 251 ± 83 mg in Group P and 159 ± 73 mg in Group C (p < 0.001). The incidence of transient hypotension was higher in Group P (p = 0.009). The recovery time and discharge time were both shorter in Group C (p < 0.001 and p = 0.006 respectively). Overall, postprocedural adverse events were similar in both groups. The postanesthetic satisfaction was comparable in both groups. TCI of propofol combined with midazolam and fentanyl achieved sedation with fewer hypotension episodes and shorter recovery and discharge time than propofol TCI alone in patients undergoing GI endoscopy.

Impact of priming the infusion system on the performance of target-controlled infusion of remifentanil

BACKGROUND

The start-up behavior of syringe and syringe pump is known to be one of the causes of inaccurate intravenous infusion. This study evaluated the method of priming the infusion system (PRIMING), and its impact on the target-controlled infusion (TCI) of two remifentanil diluents.

METHODS

PRIMING was performed using an evacuation of 2.0 ml to the atmosphere prior to TCI. Forty-eight TCI, using 50 µg/ml (Remi50) or 20 µg/ml (Remi20) of diluents, were performed targeting 4.0 ng/ml of effect-site concentration (Ceff), with PRIMING or not. The gravimetrical measurements of the delivered infusates reproduced actual Ceff. The bolus amount and time to reach 95% target were compared.

RESULTS

Without PRIMING, Remi50 infused less bolus (43 ± 23 %) than Remi20 (19 ± 9 %) (P = 0.003), and showed more delayed increase of Ceff (11.2 ± 4.0 min) than Remi20 (7.4 ± 0.4 min) (P = 0.028). However, PRIMING significantly decreased the deficit of the bolus (2 ± 1%), as well as the delay of the increase of Ceff in Remi50 (1.2 ± 0.2 min) (both P < 0.001). In addition, with PRIMING, the start-up bolus showed minimal difference to the nominal bolus (1 and 2%), and Ceff were increased to 4.0 ± 0.1 ng/ml at the expected time of peak effect, irrespective of the diluents.

CONCLUSIONS

Proper operation of the syringe pump used in the priming of the syringe may be helpful in reduction of the inaccuracy of TCI, particularly during the early phase of infusion, or the infusion of a more concentrated diluent.

False selection of syringe-brand compatibility and the method of correction during target-controlled infusion of propofol

Background

We evaluated volumetric differences of syringe brand compatibilities, and investigated the impact of false brand settings on target-controlled infusion (TCI) and their methods of correction.

Methods

Gravimetric measurement of 10 ml bolus infusions was performed using BD Plastipak (BDP) and Terumo compatible syringes, while setting to 7 different kinds of brand compatibilities (BDP, Sherwood Monoject, BD Perfusion, Braun Perfusor, Braun Omnifix, Fresenius Injectomat, and Terumo). To investigate the performance of TCI using BDP with a false setting to Terumo (BDP_TERUMO) and Terumo to BDP (TERUMO_BDP), 24 TCI targeting 4.0 µg/ml of effect-site concentration (C_eff) of propofol were performed. Subsequently, another 24 TCI were evaluated for simple corrections of false settings at 30 min. We also investigated 24 TCI using active corrections (fill-up for BDP_TERUMO, evacuation for TERUMO_BDP) based on the pharmacokinetics of propofol. The C_eff at 30 min of TCI and time to normalize to ± 5% of target concentration (T_±5%target) were compared.

Results

The C_eff of BDP_TERUMO showed negative bias and 17.2% inaccuracy, and the C_eff of TERUMO_BDP showed positive bias and 19.5% inaccuracy. The C_eff at 30 min showed no difference between the methods of correction in BDP_TERUMO or TERUMO_BDP. The T_±5%target in both the active corrections was significantly shorter than that of each simple corrections (P < 0.001).

Conclusions

False brand setting of syringe proportionally maintained different predicted concentrations as much as the volumetric differences of syringe brand. Based on the results, it is proposed that correction methods based on pharmacokinetics could effectively normalize the differences, without giving up the wrong TCI.

Effect of a target-controlled infusion of remifentanil in combination with desflurane during the "maintenance" phase of general anesthesia

Background

The goal of this study was to determine the optimal target-controlled concentration of remifentanil combined with desflurane, by using a more widely and decreasing end-tidal concentration of desflurane.

Methods

Ninety ASA I patients, who underwent general anesthesia for elective orthopedic or extremity surgeries, were registered and randomly allocated to receive either a target-controlled concentration of 1 ng/ml (group R1), 2 ng/ml (group R2) remifentanil, or desflurane only without remifentanil infusion (group D). Mean arterial pressure (MAP) and heart rate (HR) were recorded at 5-min intervals from after a 10-15 min period of surgical incision to before a 10-min period prior to the end of an operation. End-tidal concentration of desflurane was increased or decreased in proportion to the changes in MAP and HR. If the value of bispectral index (BIS) was from 60-62 for more than 2 min or systolic blood pressure would fall below 90 mmHg, the patient was excluded from the study to prevent a risk of "explicit awareness" and shock.

Results

The end-tidal desflurane concentration was lower in the group receiving 1 ng/ml (5.2 ± 0.5 vol%; P < 0.001) and 2 ng/ml remifenanil (4.4 ± 0.5 vol%; P < 0.001) compared to patients in group D (7.9 ± 0.5 vol%).

Conclusions

We recommend the use of 2 ng/ml or less remifentanil combined with desflurane for decreasing concentrations of desflurane without significant side effects, during the "maintenance" phase, and not during the induction phase of general anesthesia.

Cross-simulation between two pharmacokinetic models for the target-controlled infusion of propofol

BACKGROUND

We investigated how one pharmacokinetic (PK) model differed in prediction of plasma (C(p)) and effect-site concentration (C(eff)) using a reproducing simulation of target-controlled infusion (TCI) with another PK model of propofol.

METHODS

Sixty female patients were randomly assigned to TCI using Marsh PK (Group M) and TCI using Schnider PK (Group S) targeting 6.0 µg/ml of C(p) of propofol for induction of anesthesia, and loss of responsiveness (LOR) was evaluated. Total and separate cross-simulation were investigated using the 2 hr TCI data (Marsh TCI and Schnider TCI), and we investigated the reproduced predicted concentrations (MARSH(SCH) and SCHNIDER(MAR)) using the other model. The correlation of the difference with covariates, and the influence of the PK parameters on the difference of prediction were investigated.

RESULTS

Group M had a shorter time to LOR compared to Group S (P < 0.001), but C(eff) at LOR was not different between groups. Reproduced simulations showed different time courses of C(p). MARSH(SCH) predicted a higher concentration during the early phase, whereas SCHNIDER(MAR) was maintained at a higher concentration. Volume and clearance of the central compartment were relevant to the difference of prediction, respectively. Body weight correlated well with differences in prediction between models (R(sqr) = 0.9821, P < 0.001).

CONCLUSIONS

We compared two PK models to determine the different infusion behaviors during TCI, which resulted from the different parameter sets for each PK model.

Comparison of effect-site concentration of remifentanil for tracheal intubation with the lightwand and laryngoscopy during propofol target-controlled infusion

Background

Target-controlled infusion (TCI) of propofol and remifentanil can provide satisfactory intubating conditions without a neuromuscular blocking agent. We compared the effect-site concentration of remifentanil required for intubation with the lightwand and the Macintosh laryngoscope during propofol TCI without a neuromuscular blocking agent in adult patients.

Methods

Forty-nine patients were randomly assigned to the lightwand group (n = 25) or the direct laryngoscope group (n = 24). Anesthesia was induced by propofol TCI with an effect-site concentration of 5.4 µg/ml. Two minutes after start of propofol TCI, remifentanil was administered at the predetermined effect-site concentration. The effect-site concentration of remifentanil was determined using Dixon's up-and-down method (0.5 ng/ml as a step size). The first patient in each group was tested at 4.5 ng/ml of remifentanil. Tracheal intubation was performed 2 min after the start of remifentanil TCI. Acceptable intubation was defined as an excellent or good intubating conditions.

Results

Using a modified Dixon's up and down method, the EC50 ± SD of remifentanil in the lightwand and laryngoscope groups was 4.75 ± 0.71 ng/ml and 5.08 ± 0.52 ng/ml, respectively; there was no statistically significant difference between the groups (P = 0.373).

Conclusions

The effect-site concentration of remifentanil for acceptable intubation with the lightwand and Macintosh laryngoscope in 50% of adults did not differ during propofol TCI without a neuromuscular blocking agent.

Titration of the plasma effect site equilibrium rate constant of propofol; a link method of 'Concentration-Probability-Time'

Background

The plasma effect-site equilibrium rate constant (k_e0) of propofol has been reported in various pharmacodynamic studies; however, it is not desirable to apply k_e0 for the link with pharmacokinetic models that were separately investigated. Thus, we titrated k_e0 for the pharmacokinetic model, which is known as the multiple covariates adjusted model of propofol.

Methods

Ninety female patients scheduled for gynecologic surgery were randomly assigned to three groups targeting different plasma concentrations of 5.4, 8.1, and 10.8 µg/ml. Target-controlled infusions (TCI) were provided by a computer-assisted continuous infusion system. Time to loss of responsiveness (LOR) was measured by a blind investigator; effect-site concentrations (C_e) for LOR were then calculated with simulation of TCI using different k_e0s. We determined the k_e0 minimizing total discrepancy (TD) between the inputted and calculated k_e0 from the t_1/2k_e0s for a given probability of LOR of the C_e, and also obtained the k_e0 for the minimal TD between the median C_e, which were compared to the known k_e0.

Results

K_e0s from these two methods were 0.3692 and 0.3788/min. C_es for LOR with these k_e0s were significantly different from those with Schnider's k_e0.

Conclusions

We proposed a method for titration of the k_e0 of propofol. The k_e0s of propofol was lower than Schnider's k_e0. An adequate k_e0 for the specific pharmacokinetic model and a certain population would be useful for prediction of an accurate C_e, and could be used for calculation of accurate dosing during targeting of the effect site.

The effects of midazolam and remifentanil on induction of anesthesia and hemodynamics during tracheal intubation under target-controlled infusion of propofol

BACKGROUND

The combined induction using two or more agents has a potential benefit that anesthesia could be induced with smaller anesthetic agents with fewer side effects. We studied the effects of co-administration with midazolam and remifentanil on the dose of propofol, the time to loss of consciousness (LOC) and hemodynamics during tracheal intubation.

METHODS

Sixty patients were randomly assigned to three groups. Group 1 was induced with target-controlled propofol alone. Group 2 received midazolam (0.05 mg/kg) and target-controlled propofol. Group 3 received midazolam (0.025 mg/kg), remifentanil (2 ng/ml) and target-controlled propofol. The time to LOC, the infused propofol dose and the effect site concentration at LOC were recorded. After LOC, rocuronium (0.6 mg/kg) was given and tracheal intubation was performed. The noninvasive blood pressure, heart rate (HR) and bispectral index were recorded.

RESULTS

The time and the dose of propofol to LOC were significantly reduced in group 2, 3 than in group 1 (P < 0.05). Compared with pre-induction values, mean blood pressure at immediately after intubation was increased in group 1, 2 with no change in group 3. The HR immediately after intubation was significantly increased in all groups compared to the pre-induction values, but the rate of increase of HR in group 3 were significantly lower than those group 1, 2 (P < 0.05).

CONCLUSIONS

The co-administration with midazolam and remifentanil reduces the time to LOC and the dose of propofol. That also attenuates hemodynamics during tracheal intubation under target-controlled infusion of propofol.