Search

The automation of the delivery of anesthesia infusion rate in a general medical procedure consists of calculating the adequate infusion to regulate a patient's hypnosis state. In this procedure, the patient model has been considered as a Single‐Input Single‐Output system. However, the anesthesiologist introduces other medications, such as analgesics. Therefore, this contribution considers a closed‐loop formulation with two drugs as input control variables: propofol as an anesthetic, and remifentanil as an analgesic. Then, through the mathematical model description, this paper introduces a multiple‐input and multiple‐output (MIMO) model predictive control (MPC) to regulate the deep of hypnosis (DOH) based on the co‐administration of propofol and remifentanil. Since the control variables must be positive during the procedure, the MPC is formulated as a constrained optimization problem. Quadratic programming solves the optimization problem by designing and developing an exponential cost function, which allows the rapid convergence of the MPC optimization algorithm. Finally, the proposed MPC formulation is tested on 12 patients in silico, simulating a 60‐min general surgery. The simulated results verify the performance of the proposed MPC. [ABSTRACT FROM AUTHOR]

To compare the ease of endoscopic duodenal intubation (EDI) in dogs during maintenance of general anaesthesia with isoflurane or propofol infusion. Prospective, randomized, partially blinded clinical trial. A total of 22 dogs undergoing upper gastrointestinal tract endoscopy to include EDI were recruited. Dogs were randomly assigned isoflurane (ISO; n = 10) or propofol (PROP; n = 11) for maintenance of general anaesthesia. Following anaesthetic premedication with intramuscular medetomidine (0.005 mg kg–1) and butorphanol (0.2 mg kg–1), general anaesthesia was induced with propofol, to effect, maintained with 1.5% (vaporizer setting) isoflurane in 100% oxygen or 0.2 mg kg–1 minute–1 propofol. The dose of both agents was adjusted to maintain general anaesthesia adequate for the procedure. Degree of sedation 20 minutes post-anaesthetic premedication, propofol induction dose, anaesthetist and endoscopist training grade, animal's response to endoscopy, presence of gastro-oesophageal and duodenal-gastric reflux, spontaneous opening of the lower oesophageal and pyloric sphincters, antral movement and time to achieve EDI were recorded. EDI was scored 1 (immediate entry with minimal manoeuvring) to 4 (no entry after 120 seconds) by the endoscopist, blinded to the agent in use. Data were tested for normality (Shapiro-Wilk test) and differences between groups analysed using independent t test, Mann-Whitney U test and Fisher's exact test as appropriate. There were no significant differences between groups for EDI score [median (interquartile range): 2 (3) ISO, 2 (3) PROP] or time to achieve EDI [mean ± standard deviation: 52.50 ± 107.00 seconds (ISO), 70.00 ± 196.00 seconds (PROP)]. Significantly more dogs responded to passage of the endoscope into the oesophagus in group PROP compared with group ISO (p = 0.01). Maintenance of general anaesthesia with either isoflurane or propofol did not affect EDI score or time to achieve EDI. [ABSTRACT FROM AUTHOR]

Introduction: Introduction of more rapid and short-acting volatile anesthetics and intravenous anesthetics has allowed anesthesiologists to achieve a recovery profile that facilitates rapid emergence after general anesthesia. Both propofol and sevoflurane provide rapid induction and faster recovery by titrating the depth of anesthesia based on the BIS Index during maintenance. The objectives of the study were analysis of hemodynamic parameters, changes in the BIS Index, recovery characteristics, postoperative complications. Methods: Following IRB approval, an observational study was conducted in 60 patients of ASA grade I-II, aged 18-60 years undergoing surgical procedures under general anesthesia. Patients were randomly divided into two groups, with 30 patients each receiving propofol infusion (Group P) or sevoflurane (Group S) to maintain anesthesia. The requirement of anesthetic agents was titrated by BIS monitoring. BIS score was held between 40 to 60. Results: Hemodynamic parameters like heart rate and mean arterial pressure (MAP) were comparable in both groups. During recovery, the meantime to spontaneous ventilation, eye-opening, hand squeezing, following verbal command, extubation, stating the name, and mean time to achieve modified Aldrete's score of ≥ 9 from the cessation of the anesthetic drug was significantly shorter in Group S as compared to Group P. PONV was noted as a postoperative complication in the sevoflurane group. Conclusion: In our study, sevoflurane provided rapid emergence and faster recovery with stable hemodynamic. However, propofol appears to be an excellent alternative to sevoflurane for maintenance of anesthesia as it also provides fast recovery with a lower incidence of PONV

Abstract Background Propofol use in MRI procedures is growing worldwide especially for infants and children. Propofol causes unintended deep sedation and respiratory depression. The safety and efficacy of dexmedetomidine–propofol versus ketamine–dexmedetomidine versus dexmedetomidine alone as a based sedation regimen in specific age range of children is the study concern. Objective The aim of this study is to compare the efficacy of dexmedetomidine/propofol mixture, dexmedetomidine/ketamine, and dexmedetomidine alone for pediatric MRI sedation. Patients and methods Ninty infants and children whose body weight is more than 10 kg were enrolled in a double-blind comparative study and assigned into three equal groups for sedation, group (DK) dexmedetomidine/ ketamine, group (DP) dexmedetomidine/propofol, and group (D) dexmedetomididne alone. All patients were given premedication in the form of oral midazolam 0.5 mg/kg 30 min before the procedure. Sedation was according to group: Group (DK) received ketamine 1.5 mg /kg intravenous bolus as a loading dose and maintenance dose done by dexmedetomidine infusion with a concentration of 0.004 mg/ml and infusion rate of 1 μg/kg/h for the first 10 min then reduced infusion dose to be in between 0.6 and 1 μg/kg/h to keep the patient sedated to a Ramsay sedation score more than 4. Group (DP) received propofol 1.5 mg/kg intravenous bolus as a loading dose, then maintenance dose infusion was a mixture of dexmedetomidine with a concentration of 0.004 mg/ml and propofol 4 mg/ml; this combination is compatible (Trissel et al., 2002; Cayo, 2013). This combination will be started by a loading dose of 1 μg/kg/h for the first 10 min then 0.6 to 1 μg/kg/h, sedated with a Ramsay sedation score of more than 4. Group (D) received dexmedetomidine with a dose of 2–3 μg/kg/h as loading for 10 min then 0.6 to 1 μg/kg/h to keep the patient sedated with a Ramsay sedation score of more than 4. Results There was a significant difference between the DP group induction recovery time, hemodynamics, and Ramsey sedation score up to 5 min after the induction to the other two groups, and there was a significant difference between the DK group to the other two groups concerning emergence phenomena (agitation, altered perception, hallucination) and sedation failure. Conclusion The combination of dexmedetomidine to propofol with a low dose for sedation during MRI gives better induction + recovery time, improves hemodynamics, and decreases incidence of emergence phenomena and sedation failure.

Total intravenous anaesthesia (TIVA) is becoming more widely used, and as of yet there are few safety checks for the use of TIVA when compared to inhaled anaesthesia. This study aims to assess the feasibility and utility of introducing a TIVA checklist at a large teaching hospital. Methods A survey was sent out to all consultant and trainee anaesthetists at our hospital regarding their use of TIVA and errors in practice related to its use. A checklist was created based on common errors reported in the survey, errors described in NAP5 and our hospital's standard operating procedure. The checklist was introduced, and another survey was distributed a month later to assess compliance and utility and to gain feedback. Results In the first survey, there were 39 responses. A total of 64% had seen an error with the use of TIVA. For those using TIVA 70% of the time or more, 31% had seen an error in the last three months. Twelve per cent of those who had seen errors found that the errors led to patient harm. Only 33% used a method to double-check for errors prior to commencing TIVA. In the follow-up survey, 80% of those who used the checklist had found it useful, and 30% had corrected an error while using the checklist. Eighty-seven per cent felt the checklist would prevent errors from being made. Eighty per cent of respondents said they would use the checklist in their future practice. The checklist was found to be more useful for trainees, and for those who use TIVA less often. Discussion The 'PRESS to start TIVA" checklist has been shown to be a useful tool to prevent errors and a majority of anaesthetists at our hospital plan to use it going forward. Our data suggests that anaesthetists who are less experienced with TIVA benefit more from having a checklist. There was a marked increase in the number of anaesthetists who would use a checklist in the future, compared to those who used one in the initial survey. This shows that introducing a checklist is feasible and is likely to reduce errors going forward., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2024, Woodward et al.)

Abstract: The aim of this study was to determine the relationship, precision, and bias of a propofol target‐controlled infusion (TCI) system during prolonged infusion in neurosurgical patients. We retrospectively included patients undergoing general anesthesia for elective neurosurgical removal of brain tumors and postoperative sedation in the intensive care unit over a period of 3 months. TCI of propofol (Diprifusor – Marsh model) and remifentanil were used for general anesthesia and sedation. We compared propofol blood concentration (Cmeas) measured by liquid chromatography–mass spectroscopy with predicted concentrations (Cpred) by the TCI system at 40 minutes (T0), 2 hours (T1), and 4 hours (T2) and every 8 hours after starting the drug infusion and at the time of emergence from sedation. Ninety‐four paired determinations of Cmeas and Cpred from 15 adult ASA I patients (8 men and 7 women 54.9 ± 13 years old; BMI, 24 ± 3.2 kg/m2) were analyzed. Mean duration of drug administration was 31 ± 6 hours. The coefficient of determination (R2) of the linear regression model for the relationship of Cmeas and Cpred was 0.43. At the time of emergence, Cmeas was 0.5 ± 0.18 μg/mL. The bias of the TCI system (median performance error) was ‐34.7%, and the precision (median absolute performance error) was 36%. Wobble and divergence were 0.3% and 12.3%, respectively. This study found bias of the system out of the range of tolerability and showed a high tendency toward overestimation. These findings may lead to undersedation when propofol TCI is used for prolonged infusion. [ABSTRACT FROM AUTHOR]

Background: Facial nerve monitoring, often required during total parotidectomy, precludes use of long acting muscle relaxants and propofol infusion is used solely to ensure patient immobility. We aimed to compare intraoperative patient immobility, hemodynamic stability and propofol consumption during total parotidectomy following a transtracheal block. Material and Methods: Forty patients were allocated to 2 equal groups. Preoperatively, group A patients received transtracheal block with 4 ml of 4% lidocaine, while no block was given to patients in group B. If there was patient movement, tachycardia or hypertension, group A patients received a bolus of propofol 30 mg and propofol infusion was started (100mg/hr). In group B, propofol infusion was started (100mg/hr) soon after intubation. Result: Both group A and B were comparable with respect to patient immobility and hemodynamic stability. There was no intraoperative propofol requirement in group A. Conclusion: Transtracheal block is a safe and successful alternative to propofol infusion during surgeries where muscle relaxants are to be avoided.

Ornithine transcarbamylase (OTC) deficiency is the most common genetic disorder of the urea cycle. These disorders are characterized by an inability to metabolize ammonia into urea, leading to hyperammonemia with variable physiological consequences and presenting important anesthetic challenges, especially the perioperative prevention of hyperammonemia and management of its consequences, should it occur. Idiopathic scoliosis (IS) is the most common spinal deformity requiring surgical treatment. This paper presents the case of a 16-year-old female with OTC deficiency who underwent spinal fusion for IS. The chosen anesthetic strategy was combined anesthesia with total intravenous general anesthesia using target-controlled infusion pumps, an erector spinae plane block (ESPB), and a multi-pronged approach to ensure metabolic control while avoiding hyperammonemia. The existing literature regarding major surgery in patients with OTC deficiency is sparse, and this paper provides one of the first case reports of a scoliosis correction surgery, as well as one of the first descriptions of prolonged propofol infusion and locoregional anesthesia with an erector spinae plane block in this context., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2023, Pinto et al.)

Background: Facial nerve monitoring, often required during total parotidectomy, precludes use of long acting muscle relaxants and propofol infusion is used solely to ensure patient immobility. We aimed to compare intraoperative patient immobility, hemodynamic stability and propofol consumption during total parotidectomy following a transtracheal block. Material and Methods: Forty patients were allocated to 2 equal groups. Preoperatively, group A patients received transtracheal block with 4 ml of 4% lidocaine, while no block was given to patients in group B. If there was patient movement, tachycardia or hypertension, group A patients received a bolus of propofol 30 mg and propofol infusion was started (100mg/hr). In group B, propofol infusion was started (100mg/hr) soon after intubation. Result: Both group A and B were comparable with respect to patient immobility and hemodynamic stability. There was no intraoperative propofol requirement in group A. Conclusion: Transtracheal block is a safe and successful alternative to propofol infusion during surgeries where muscle relaxants are to be avoided. [ABSTRACT FROM AUTHOR]

Study Objective: To assess the effect of two different remifentanil infusion doses on hemodynamic stability and recovery characteristics in children undergoing tracheobronchial foreign body removal during rigid bronchoscopy. Design: Prospective, randomized, clinical comparison study. Setting: Operating room of a university hospital. Patients: 70 ASA physical status 1 and 2 children, aged 3-12 years, presenting for tracheobronchial foreign body removal during rigid bronchoscopy. Interventions: Children were divided equally into two groups to receive either a 0.1 μg/kg/min (Group R1) or 0.2 μg/kg/min (Group R2) remifentanil infusion. Ten minutes after the remifentanil infusion, 3 mg/kg of propofol and 0.02 mg/kg of atropine were given. Anesthesia was maintained with 0.1 μg/kg/min of remifentanil and 100-250 μg/kg/min of propofol in Group R1 and 0.2 μg/kg/min of remifentanil and 100-250 μg/kg/min of propofol in Group R2. After baseline measurements were recorded, 0.2 mg/kg of mivacurium was given intravenously. Ventilation was maintained with 100% O2 via a "T" piece connected to the side arm of the bronchoscope. Measurements: Heart rate (HR), systolic (SBP), diastolic (DBP) and mean arterial pressures (MAP), and O2 saturation (SpO2) were recorded before (baseline) and after induction, and 1, 3, 5, 10, 15, 20, 25, and 30 minutes after insertion of the rigid bronchoscope into the trachea. Emergence characteristics and complications were noted. Statistical analysis was performed using independent samples t-test, repeated measures, and chi-square test as appropriate. Main Results: Groups were similar in demographics and duration of bronchoscopy and anesthesia (P N 0.05). In Group R1, HR, SBP, DBP, and MAP increased one minute after insertion of the bronchoscope in Group R1 (P b 0.01). Propofol consumption was significantly higher in Group R1 (63.6 ± 30.1 mg) than Group R2 (39.8 ± 26.6 mg; P b 0.01). Time to spontaneous eye opening was 8.6 ± 1.3 minutes in Group R1 and 6.3 ± 1.1 minutes in Group R2 (P b 0.05). The time to recovery to an Aldrete score of 9 was greater in Group R1 (19.8± 3.0 min) than Group R2 (16.1±3.0 min; P b 0.01). Conclusion: A remifentanil 0.2 μg/kg/min infusion with propofol provides hemodynamic stability and early recovery in children undergoing foreign body removal during rigid bronchoscopy. [ABSTRACT FROM AUTHOR]

The article discusses a study which aimed to determine the optimal dose of effect-site concentrations of remifentanil required for the successful insertion of Streamlined Liner of the Pharynx Airway (SLIPA) and to compare it to that required for laryngeal mask airway (LMA) insertion in patients receiving a propofol infusion. In this study, airway device insertion was classified as success or failure based on patient response.

This report provides a description and discussion of a 19-year-old, 65-kg male, with a large mediastinal mass, right pleural effusion, and pericardial effusion, requiring urine alkalinization during a propofol infusion. The patient required NaHCO3 boluses, urine pH, electrolyte, arterial blood gas and lactate monitoring, and discontinuation of the propofol. The authors suggest that caution be used when prescribing a propofol infusion for patients who are at risk of tumor lysis syndrome and the need for urine alkalinization. [ABSTRACT FROM AUTHOR]

Background: Transcranial stimulation of the motor cortex using high-voltage electrical stimuli given in train is a method of monitoring the integrity of the motor pathways during thoracoabdominal aortic aneurysm surgery. The purpose of this study was to assess the relationship between the stimulus intensity and the corresponding amplitude of the myogenic motor evoked potential (tcMEP) in response to six-pulse transcranial electrical stimulation during two levels of low-dose propofol infusion and stable fentanyl/nitrous oxide anaesthesia. Methods: Nine patients (37–78 yr) scheduled to undergo surgery on the thoracoabdominal aorta were studied. After achieving a stable anaesthetic state the output voltage was decreased with 50 V intervals from 350 V to 200 V during a target propofol infusion aimed at a plasma steady-state concentration of 0.7 μg · ml-1 and increased with 50 V intervals from 200 V to 450 V during a target propofol infusion aimed at a plasma steady-state concentration of 1.4 μg · ml-1. TcMEPs were recorded from the right tibialis anterior muscle. Results: Doubling the target propofol infusion to 1.4 μg · ml-1 resulted in a 30–50% decrease in tcMEP amplitude. The largest tcMEP amplitude using the six-pulse paradigm was found during a propofol infusion aimed at a plasma concentration of 0.7 μg · ml-1 and demanded a stimulus output of 350 V, corresponding to a charge density of 7.5 μC · cm-2 per phase. Conclusion: Doubling the target propofol infusion to 1.4 μg · ml-1 provides less robust, but still recordable tcMEPs in response to six-pulse electrical stimulation. Safety guidelines are discussed. [ABSTRACT FROM AUTHOR]

Background: Propofol use in MRI procedures is growing worldwide especially for infants and children. Propofol causes unintended deep sedation and respiratory depression. The safety and efficacy of dexmedetomidine–propofol versus ketamine–dexmedetomidine versus dexmedetomidine alone as a based sedation regimen in specific age range of children is the study concern. Objective: The aim of this study is to compare the efficacy of dexmedetomidine/propofol mixture, dexmedetomidine/ketamine, and dexmedetomidine alone for pediatric MRI sedation. Patients and methods: Ninty infants and children whose body weight is more than 10 kg were enrolled in a double-blind comparative study and assigned into three equal groups for sedation, group (DK) dexmedetomidine/ ketamine, group (DP) dexmedetomidine/propofol, and group (D) dexmedetomididne alone. All patients were given premedication in the form of oral midazolam 0.5 mg/kg 30 min before the procedure. Sedation was according to group: Group (DK) received ketamine 1.5 mg /kg intravenous bolus as a loading dose and maintenance dose done by dexmedetomidine infusion with a concentration of 0.004 mg/ml and infusion rate of 1 μg/kg/h for the first 10 min then reduced infusion dose to be in between 0.6 and 1 μg/kg/h to keep the patient sedated to a Ramsay sedation score more than 4. Group (DP) received propofol 1.5 mg/kg intravenous bolus as a loading dose, then maintenance dose infusion was a mixture of dexmedetomidine with a concentration of 0.004 mg/ml and propofol 4 mg/ml; this combination is compatible (Trissel et al., 2002; Cayo, 2013). This combination will be started by a loading dose of 1 μg/kg/h for the first 10 min then 0.6 to 1 μg/kg/h, sedated with a Ramsay sedation score of more than 4. Group (D) received dexmedetomidine with a dose of 2–3 μg/kg/h as loading for 10 min then 0.6 to 1 μg/kg/h to keep the patient sedated with a Ramsay sedation score of more than 4. Results: There was a significant difference between the DP group induction recovery time, hemodynamics, and Ramsey sedation score up to 5 min after the induction to the other two groups, and there was a significant difference between the DK group to the other two groups concerning emergence phenomena (agitation, altered perception, hallucination) and sedation failure. Conclusion: The combination of dexmedetomidine to propofol with a low dose for sedation during MRI gives better induction + recovery time, improves hemodynamics, and decreases incidence of emergence phenomena and sedation failure. [ABSTRACT FROM AUTHOR]