Intravenous Regional Anesthesia: A Historical Overview and Clinical Review.

Intravenous regional anesthesia (IVRA) is an established, safe and simple technique, being applicable for various surgeries on the upper and lower limbs. In 1908, IVRA was first described by the Berlin surgeon August Bier, hence the name "Bier's Block". Although his technique was effective, it was cumbersome and fell into disuse when neuroaxial and percutaneous plexus blockades gained widespread popularity in the early 20th century. In the 1960s, it became widespread, when the New Zealand anesthesiologist Charles McKinnon Holmes praised its use by means of new available local anesthetics. Today, IVRA is still popular in many countries being used in the emergency room, for outpatients and for high-risk patients with contraindications for general anesthesia. IVRA offers a favorable risk-benefit ratio, cost-effectiveness, sufficient muscle relaxation and a fast on- and offset. New upcoming methods for monitoring, specialized personnel and improved emergency equipment made IVRA even safer. Moreover, IVRA may be applied to treat complex regional pain syndromes. Prilocaine and lidocaine are considered as first-choice local anesthetics for IVRA. Also, various adjuvant drugs have been tested to augment the effect of IVRA, and to reduce post-deflation tourniquet pain. Since major adverse events are rare in IVRA, it is regarded as a very safe technique. Nevertheless, systemic neuro- and cardiotoxic side effects may be linked to an uncontrolled systemic flush-in of local anesthetics and must be avoided. This review gives a historical overview of more than 100 years of experience with IVRA and provides a current view of IVRA with relevant key facts for the daily clinical routine.

The Effect of Dexmedetomidine on Propofol Requirements During Anesthesia Administered by Bispectral Index-Guided Closed-Loop Anesthesia Delivery System: A Randomized Controlled Study.

BACKGROUND: Dexmedetomidine, a selective α2-adrenergic agonist currently approved for continuous intensive care unit sedation, is being widely evaluated for its role as a potential anesthetic. The closed-loop anesthesia delivery system (CLADS) is a method to automatically administer propofol total intravenous anesthesia using bi-spectral index (BIS) feedback and attain general anesthesia (GA) steady state with greater consistency. This study assessed whether dexmedetomidine is effective in further lowering the propofol requirements for total intravenous anesthesia facilitated by CLADS. METHODS: After ethics committee approval and written informed consent, 80 patients undergoing elective major laparoscopic/robotic surgery were randomly allocated to receive GA with propofol CLADS with or without the addition of dexmedetomidine. Quantitative reduction of propofol and quality of depth-of-anesthesia (primary objectives), intraoperative hemodynamics, incidence of postoperative adverse events (sedation, analgesia, nausea, and vomiting), and intraoperative awareness recall (secondary objectives) were analyzed. RESULTS: There was a statistically significant lowering of propofol requirement (by 15%) in the dexmedetomidine group for induction of anesthesia (dexmedetomidine group: mean ± standard deviation 0.91 ± 0.26 mg/kg; nondexmedetomidine group: 1.07 ± 0.23 mg/kg, mean difference: 0.163, 95% CI, 0.04-0.28; P = .01) and maintenance of GA (dexmedetomidine group: 3.25 ± 0.97 mg/kg/h; nondexmedetomidine group: 4.57 ± 1.21 mg/kg/h, mean difference: 1.32, 95% CI, 0.78-1.85; P < .001). The median performance error of BIS control, a measure of bias, was significantly lower in dexmedetomidine group (1% [-5.8%, 8%]) versus nondexmedetomidine group (8% [2%, 12%]; P = .002). No difference was found for anesthesia depth consistency parameters, including percentage of time BIS within ±10 of target (dexmedetomidine group: 79.5 [72.5, 85.3]; nondexmedetomidine group: 81 [68, 88]; P = .534), median absolute performance error (dexmedetomidine group: 12% [10%, 14%]; nondexmedetomidine group: 12% [10%, 14%]; P = .777), wobble (dexmedetomidine group: 10% [8%, 10%]; nondexmedetomidine group: 8% [6%, 10%]; P = .080), and global score (dexmedetomidine group: 25.2 [23.1, 35.8]; nondexmedetomidine group: 24.7 [20, 38.1]; P = .387). Similarly, there was no difference between the groups for percentage of time intraoperative heart rate and mean arterial pressure remained within 20% of baseline. However, addition of dexmedetomidine to CLADS propofol increased the incidence of significant bradycardia (dexmedetomidine group: 14 [41.1%]; nondexmedetomidine group: 3 [9.1%]; P = .004), hypotension (dexmedetomidine group: 9 [26.5%]; nondexmedetomidine group: 2 [6.1%]; P = .045), and early postoperative sedation. CONCLUSIONS: The addition of dexmedetomidine to propofol administered by CLADS was associated with a consistent depth of anesthesia along with a significant decrease in propofol requirements, albeit with an incidence of hemodynamic depression and early postoperative sedation.

Equipment failure of intravenous syringe pump detected by increase in Narcotrend stage: A case report.

RATIONALE: Awareness is the recovery of consciousness during general anesthesia. It occurs when patients under general anesthesia receive inadequate anesthetic medications to maintain unconsciousness during surgery. Equipment failure is a common cause of intraoperative awareness. PATIENT CONCERNS: A 16-year-old boy, 85 kg in weight, was admitted to our hospital for thyroglossal cystectomy under general anesthesia. Six minutes after the intubation, we noted that the Narcotrend index indicated a condition of light anesthesia and the patient was observed to be in tears. DIAGNOSIS: Improper positioning of the syringe fixing clamp on the CP700TCI infusion pump caused equipment failure and light anesthesia. INTERVENTIONS: Bolus of 50 mg propofol and 2 mg midazolam were administered manually by syringe, and inhalation of 2% sevoflurane was supplemented. Infusion pump was replaced. OUTCOMES: The Narcotrend index of the patient returned to state of deep anesthesia following manual administration of the anesthetic medications. Following the surgery, the patient had an uneventful recovery, and did not present with evidence of awareness. LESSONS: Users of the CP700TCI syringe pump should pay attention to the position of the syringe fixing clamp. Anesthesiologists should check all the equipment according to a defined checklist prior to anesthesia. Narcotrend monitor could help to detect light anesthesia and prevent potential awareness.

Improving the anesthetic process by a fuzzy rule based medical decision system.

OBJECTIVE: The main objective of this research is the design and implementation of a new fuzzy logic tool for automatic drug delivery in patients undergoing general anesthesia. The aim is to adjust the drug dose to the real patient needs using heuristic knowledge provided by clinicians. A two-level computer decision system is proposed. The idea is to release the clinician from routine tasks so that he can focus on other variables of the patient. METHODS: The controller uses the Bispectral Index (BIS) to assess the hypnotic state of the patient. Fuzzy controller was included in a closed-loop system to reach the BIS target and reject disturbances. BIS was measured using a BIS VISTA monitor, a device capable of calculating the hypnosis level of the patient through EEG information. An infusion pump with propofol 1% is used to supply the drug to the patient. The inputs to the fuzzy inference system are BIS error and BIS rate. The output is infusion rate increment. The mapping of the input information and the appropriate output is given by a rule-base based on knowledge of clinicians. RESULTS: To evaluate the performance of the fuzzy closed-loop system proposed, an observational study was carried out. Eighty one patients scheduled for ambulatory surgery were randomly distributed in 2 groups: one group using a fuzzy logic based closed-loop system (FCL) to automate the administration of propofol (42 cases); the second group using manual delivering of the drug (39 cases). In both groups, the BIS target was 50. CONCLUSIONS: The FCL, designed with intuitive logic rules based on the clinician experience, performed satisfactorily and outperformed the manual administration in patients in terms of accuracy through the maintenance stage.

Design and Evaluation of a Closed-Loop Anesthesia System With Robust Control and Safety System.

BACKGROUND: Closed-loop control of anesthesia involves continual adjustment of drug infusion rates according to measured clinical effect. The NeuroSENSE monitor provides an electroencephalographic measure of depth of hypnosis (wavelet-based anesthetic value for central nervous system monitoring [WAVCNS]). It has previously been used as feedback for closed-loop control of propofol, in a system designed using robust control engineering principles, which implements features specifically designed to ensure patient safety. Closed-loop control of a second drug, remifentanil, may be added to improve WAVCNS stability in the presence of variable surgical stimulation. The objective of this study was to design and evaluate the feasibility of a closed-loop system for robust control of propofol and remifentanil infusions using WAVCNS feedback, with an infusion safety system based on the known pharmacological characteristics of these 2 drugs. METHODS: With Health Canada authorization, research ethics board approval, and informed consent, American Society of Anesthesiologists I-III adults, requiring general anesthesia for elective surgery, were enrolled in a 2-phase study. In both phases, infusion of propofol was controlled in closed loop during induction and maintenance of anesthesia, using WAVCNS feedback, but bounded by upper- and lower-estimated effect-site concentration limits. In phase I, remifentanil was administered using an adjustable target-controlled infusion and a controller was designed based on the collected data. In phase II, remifentanil was automatically titrated to counteract rapid increases in WAVCNS. RESULTS: Data were analyzed for 127 patients, of median (range) age 64 (22-86) years, undergoing surgical procedures lasting 105 (9-348) minutes, with 52 participating in phase I and 75 in phase II. The overall control performance indicator, global score, was a median (interquartile range) 18.3 (14.2-27.7) in phase I and 14.6 (11.6-20.7) in phase II (median difference, -3.25; 95% confidence interval, -6.35 to -0.52). The WAVCNS was within ±10 of the setpoint for 84.3% (76.6-90.6) of the maintenance of anesthesia in phase I and 88.2% (83.1-93.4) in phase II (median difference, 3.7; 95% confidence interval, 0.1-6.9). The lower propofol safety bound was activated during 30 of 52 (58%) cases in phase I and 51 of 75 (68%) cases in phase II. CONCLUSIONS: Adding closed-loop control of remifentanil improved overall controller performance. This controller design offers a robust method to optimize the control of 2 drugs using a single sensor. The infusion safety system is an important component of a robust automated anesthesia system, but further research is required to determine the optimal constraints for these safe conditions.

Anaesthetic depth control using closed loop anaesthesia delivery system vs. target controlled infusion in patients with moderate to severe left ventricular systolic dysfunction.

OBJECTIVES: To compare the efficacy of anaesthetic depth control using Closed Loop Anaesthesia Delivery System (CLADS) and Target Controlled Infusion (TCI) in patients with moderate to severe left ventricular dysfunction (LVSD). DESIGN: Randomized control trial. PATIENTS: Forty ASA III/IV adult patients with moderate to severe LVSD scheduled for open heart surgery. INTERVENTIONS: Propofol was administered using CLADS or TCI for maintaining BIS of 50. Induction and maintenance doses were controlled automatically in CLADS. Dixon's up and down method was used to estimate the plasma concentration needed for induction in TCI. MEASUREMENT: Percentage of total anaesthesia time ("valid CLADS time") for which BIS remained within ±10 of target (BIS=50). MAIN RESULTS: BIS remained within ±10 of the target for a significantly longer duration of time in CLADS group (p=0.001). Performance parameters like Median Performance Error (MDPE), p=0.024; Median Absolute Performance Error (MDAPE), p=0.0212; and global score p=0.017 were significantly better in CLADS group. Total propofol consumption was significantly less in CLADS group (p=0.014). Mean value (95% CI) of EC50 and EC95 for target plasma propofol concentration for induction was 1.62 (1.45-1.79) µgml-1 and 1.87 (1.73-2.96) µgml-1 respectively using probit analysis. CONCLUSIONS: Closed loop delivery of propofol using CLADS performed significantly better than TCI in this subset of patients. CLINICAL TRIALS REGISTRATION NO.: www.ClinicalTrials.gov-NCT02645994.

Hypnosis closed loop TCI systems in outpatient surgery. / Sistemas de TCI en circuito cerrado para la hipnosis en cirugía ambulatoria.

OBJECTIVE: Determine the influence of general anaesthesia with closed-loop systems in the results of outpatient varicose vein surgery. PATIENTS AND METHODS: Retrospective observational study including data from 270 outpatients between 2014 and 2015. The patients were divided into 2 groups according to the type of general anaesthesia used. The CL Group included patients who received propofol in closed-loop guided by BIS and remifentanil using TCI, and the C Group received non-closed-loop anaesthesia. Age, sex, surgical time, discharge time and failure of outpatient surgery were recorded. Quantitative data were checked for normal distribution by the method of Kolmogorov-Smirnov-Lilliefors. Differences between groups were analysed by a Student-t-test or Mann-Whitney-Wilcoxon test, depending on their distribution. Categorical data were analysed by a Chi-squared test. We used Kaplan-Meier estimator and the effect size (calculated by Cohen's d) to study the discharge time. Statistical analysis was performed using R 3.2.3 binary for Mac OS X 10.9. RESULTS: There were no significant differences in age, sex and surgical time and failure of outpatient surgery. Discharge time was different in both groups: 200 (100) vs. 180 (82.5) minutes, C Group and CL Group, respectively (data are median and interquartile rank); P=.005. CONCLUSION: The use of closed-loop devices for the hypnotic component of anaesthesia hastens discharge time. However, for this effect to be clinically significant, some improvements still need to be made in our outpatient surgery units.

Feasibility of Automated Propofol Sedation for Transcatheter Aortic Valve Implantation: A Pilot Study.

BACKGROUND: Recently, several trials have shown that closed-loop sedation is feasible. No study has used automated sedation in extremely frail patients, such as those scheduled for transcatheter aortic valve implantation (TAVI). We developed and tested a novel automated sedation system for this kind of population and surgery. The system integrates a decision support system that detects respiratory and hemodynamic events via smart alarms, which provide pertinent/related clinical suggestions and treatment options. The main objective was the feasibility of closed-loop sedation, defined as successful automated sedation without manual override. Secondary qualitative observations were clinical and controller performance. METHODS: Twenty patients scheduled for elective TAVI were enrolled. Sedation was administered via a closed-loop delivery system designed for propofol. The clinical performance of sedation was the efficacy to maintain a bispectral index (BIS) of 65. To evaluate the sedation performance, BIS values were stratified into 4 categories: excellent, very good, good, and inadequate sedation control, defined as BIS values within 10%, ranging from 11% to 20%, ranging from 21% to 30%, or >30% from the target value, respectively. The controller performance was calculated using Varvel parameters. Critical respiratory and hemodynamic events were documented. The former was defined as peripheral oxygen saturation <92% and/or respiratory rate <8/min, whereas the latter was considered a mean arterial pressure <60 mm Hg and/or heart rate <40 bpm. RESULTS: Automated sedation was successful in 19 patients undergoing TAVI. One patient was excluded from the final analysis because of conversion to general anesthesia. The secondary observations revealed that the clinical performance allowed an excellent to good control during 69% (99% confidence interval, 53%-77%; interquartile range, 59%-79%) of the sedation time. Fifteen patients presented critical respiratory episodes, with a median of 3 events per hour of sedation. Six patients presented critical hemodynamic episodes, with a median of 2 events per hour of procedure. CONCLUSIONS: The automated closed-loop sedation system tested could be used successfully for patients scheduled for a TAVI procedure. The results showed a satisfactory clinical performance of sedation control.

Simulator evaluation of a prototype device to reduce medication errors in anaesthesia.

We undertook a randomised control led trial to evaluate the effect of a prototype device which attaches to the intravenous drug administration port, and allows injection of intravenous drugs only after the user scans the barcode on the syringe label. This requires two steps: first, that the correct drug label is generated; and second, that the syringe-with-label is scanned before administration. Ten anaesthetists, who were unaware of the primary outcome being measured, administered general anaesthesia for two simulated standardised cases each without and with our prototype (control and intervention, respectively). The primary outcome measured was compliance with a safe drug administration procedure (defined as a two-step procedure where, step one is scanning a drug ampoule to print a label for a syringe and step two is scanning of the labelled syringe before administering it intravenously). A total of 182 intravenous drug administrations occurred in the study (91 in each group). We found that the use of our prototype increased safe drug administration behaviour in experienced anaesthetists; 33 (36.3% [95% CI 26-47%]) vs. 91 (100% [95% CI 96-100%]) in the control and intervention groups, respectively (p = 0.0001).

A Multicenter Evaluation of a Closed-Loop Anesthesia Delivery System: A Randomized Controlled Trial.

BACKGROUND: Closed-loop systems for anesthesia delivery have been shown to outperform traditional manual control in different clinical settings. The present trial was aimed at evaluating the feasibility and efficacy of Bispectral Index (BIS)-guided closed-loop anesthesia delivery system (CLADS) in comparison with manual control across multiple centers in India. METHODS: Adult patients scheduled for major surgical procedures of an expected duration of 1 to 3 hours were randomized across 6 sites into 2 groups: a CLADS group and a manual group. In the manual control group, propofol infusion was titrated manually by the attending anesthesiologist to a BIS of 50 during induction and maintenance. Analgesia was maintained with fentanyl infusion and nitrous oxide in both groups. In the CLADS group, both induction and maintenance of anesthesia were performed automatically using CLADS. The primary outcome measure was the performance of the system as assessed by the percentage of total anesthesia time BIS remained ±10 of target BIS. The secondary outcome measures were a percentage of anesthesia-time heart rate and mean arterial pressure within 25% of the baseline, median absolute performance error, wobble, and global score. Wobble indicates intraindividual variability in the control of BIS, and global score reflects the overall performance; lower values indicate superior performance for both parameters. The performance parameters of the system also were compared among the participating sites. RESULTS: Two hundred forty-two patients were randomized. BIS was maintained within ±10 of target for significantly longer time in the CLADS group (81.4% ± 8.9 % of anesthesia duration) than in the manual group (55.34% ± 25%, P < 0.0001). The indices that assess performance were significantly better in the CLADS group than the manual group as follows: median absolute performance error was 10 (10, 12) (median [interquartile range]) in the CLADS group versus 18 (14, 24) in the manual group, P < 0.0001; wobble was 9 (8, 10) in CLADS group versus 10 (8, 14) in the manual group, P = 0.0009; and Global score, which reflects overall performance, was 24 (19, 30) in the CLADS group versus 51 (31, 99) in the manual group, P < 0.0001. The percentage of time heart rate was within 25% of the baseline was significantly greater in the CLADS group (heart rate of 95 [87, 99], median [interquartile range], in the CLADS group versus 90 [75, 98] in the manual group P = 0.0031). On comparison of data between the centers, the performance parameters did not differ significantly among the centers in the CLADS group (P = 0.94), but the parameters differed significantly among the centers in the manual group (P < 0.001). CONCLUSIONS: Our study in a multicenter setting proves the consistently better performance of automated anesthesia drug delivery compared with conventional manual control. This highlights an important advantage of an automated system for delivering standardized anesthesia, thereby overcoming differences in practices among anesthesiologists.

Leaving more than your fingerprint on the intravenous line: a prospective study on propofol anesthesia and implications of stopcock contamination.

BACKGROUND: Acute care handling of IV stopcocks during anesthesia and surgery may result in contaminated IV tubing sets. In the context of widespread propofol use, a nutrient-rich hypnotic drug, we hypothesized that propofol anesthesia increases bacterial contamination of IV stopcocks and may compromise safety of IV tubing sets when continued to be used after propofol anesthesia. METHODS: We conducted an in vitro trial by collecting IV tubing sets at the time of patient discharge from same-day ambulatory procedures performed with and without propofol anesthesia. These extension sets were then held at room temperature for 6, 24, or 48 hours. We cultured 50 samples at each interval for both cohorts. Quantitative cultures were done by aspirating the IV stopcock dead space and plating the aspirate on blood agar for colony count and speciation. RESULTS: Positive bacterial counts were recovered from 17.3% of propofol anesthesia stopcocks (26/150) and 18.6% of nonpropofol stopcocks (28/150). At 6 hours, the average bacterial counts from stopcocks with visible residual propofol was 44 colony forming units (CFU)/mL, compared with 41 CFU/mL with no visible residual propofol and 37 CFU/mL in nonpropofol anesthesia stopcocks. There was a 100-fold increase in bacterial number in contaminated stopcock dead spaces at 48 hours after propofol anesthesia. This difference remained significant when comparing positive counts from stopcocks with no visible residual propofol and nonpropofol anesthesia (P = 0.034). CONCLUSIONS: There is a covert incidence and degree of IV stopcock bacterial contamination during anesthesia which is aggravated by propofol anesthetic. Propofol anesthesia may increase risk for postoperative infection because of bacterial growth in IV stopcock dead spaces.

Anesthesia through an intraosseous line using an 18-gauge intravenous needle for emergency pediatric surgery.

STUDY OBJECTIVE: To describe the success and complication rate of intraosseous (IO) access for delivery of anesthesia with the use of an 18-gauge (G) intravenous (IV) needle. DESIGN: Prospective study. SETTING: Children's Welfare Teaching Hospital, Baghdad, Iraq. PATIENTS: 300 critically ill infants and toddlers, age 3 weeks to 16 months, requiring emergency surgery for intra-abdominal or pelvic conditions, in whom peripheral or central access was not obtainable. Patients presented for surgery between 2007 and 2010. INTERVENTIONS: In 26 patients, the IO catheter was established when peripheral access was not obtained at the outset of surgery; in 4 patients standard peripheral vascular access failed during the surgical procedure and IO access was obtained. An 18-G IV needle was placed into the proximal tibia and attached to an extension set with a 3-way stopcock to deliver anesthesia. MAIN RESULTS: For 26 critically ill children and 4 other children, IV access failed during delivery of anesthesia; vascular access was successfully obtained within minutes in all 30 infants (100%) using the intraosseous route. Ninety percent (27/30) of patients awoke immediately postoperatively in good condition; 10% (3/30) went to the pediatric intensive care unit (PICU) for further care due to their critical preoperative condition. Complications associated with use of the IO route were considered minor (3/30 pts [10%]) and included extravasation of fluid in two cases and cellulitis in one. CONCLUSION: The IO route provided for rapid delivery of anesthesia, induction, and maintenance in this series of critically ill infants undergoing emergency surgery when other vascular access routes failed. Few complications were noted. Intraosseous access was achieved through a simple technique using an 18-gauge IV needle.

[Case of delayed awakening after remifentanil leakage out of a vein].

We report a case of delayed awakening with characteristic repeated loss of consciousness after remifentanil infusion complicated by leakage from an intravenous catheter. A 30-year-old male underwent microlaryngeal surgery for a vocal cord polyp. During anesthetic induction, infiltration from an intravenous (IV) line in the left forearm was observed 10 min after initiating a continuous infusion of remifentanil 0.5 microg x kg-1 x min -1. A second peripheral IV catheter was placed in the right forearm and general anesthesia was induced with remifentanil infusion at 0.3 microg x kg-1 x min- 1, propofol 120mg, fentanyl 100 microg, and rocuronium 70 mg. Anesthesia was maintained with remifentanil 0.05-0.3 microg x kg-1 x min -1and sevoflurane (1.5% in oxygen) for the 4 min of surgery. A few minutes after tracheal extubation, the patient developed respiratory arrest and loss of consciousness. We immediately ventilated him with a bag-valve-mask and administered naloxone 0.04 mg. Thereafter, he repeatedly awoke and was drowsy three times over the next 5hr. It was followed by an uneventful postoperative period. No remarkable deficit was observed in the patient. Blood gases, electrolytes, glucose values, and body temperature were within normal ranges throughout the perioperative period. Brain computed tomography, mag- netic resonance imaging, and electroencephalography showed no abnormalities. It was considered that the incidental subcutaneous remifentanil accumulation may have caused the respiratory suppression and delayed awakening.

Efficacy of endotracheal lidocaine administration with continuous infusion of remifentanil for attenuating tube-induced coughing during emergence from total intravenous anesthesia.

PURPOSE: Although attenuation of tube-induced coughing is necessary in specific types of surgery, the best method for such attenuation is still unclear. We studied the combined intervention of endotracheal lidocaine and intravenous remifentanil compared to intravenous remifentanil alone with respect to coughing during emergence from anesthesia. METHODS: We examined 60 ASA 1-2 patients (age, 20-69 years) undergoing tympanoplasty under general anesthesia. Anesthesia was induced with propofol, remifentanil, and rocuronium. The trachea was intubated using a laryngotracheal instillation of topical anaesthetic (LITA) tracheal tube. Anesthesia was maintained with propofol and remifentanil (0.1-0.3 µg/kg/min). Propofol was discontinued and remifentanil (0.1 µg/kg/min) was continued at the end of the operation. Patients were randomly allocated to the lidocaine (n = 30) and control groups (n = 30). We administered 3 ml 4 % lidocaine via the LITA tube to patients in lidocaine group at the end of the operation. The trachea was extubated when the patient regained consciousness and followed orders. Coughing was evaluated using a 4-point scale by an observer who examined the video records at extubation. RESULTS: Fewer patients in lidocaine group (8 of 30) than in control group (18 of 30, p < 0.01) coughed. Fewer patients in lidocaine group (2 of 30) than in control group (12 of 30, p < 0.01) had moderate or severe cough (scale 2 or 3). CONCLUSIONS: This study is consistent with the finding that endotracheal lidocaine administration and continuous infusion of remifentanil before extubation is useful to prevent coughing on emergence from anesthesia.

Transcontinental anaesthesia: a pilot study.

BACKGROUND: Although telemedicine is one of the key initiatives of the World Health Organization, no study has explored the feasibility and efficacy of teleanaesthesia. This bi-centre pilot study investigates the feasibility of transcontinental anaesthesia. METHODS: Twenty patients aged ≥ 18 yr undergoing elective thyroid surgery for ≥ 30 min were enrolled in this study. The remote and local set-up was composed of a master-computer (Montreal) and a slave-computer (Pisa). Standard Internet connection, remote desktop control, and video conference software were used. All patients received total i.v. anaesthesia controlled remotely (Montreal). The main outcomes were feasibility, clinical performance, and controller performance of transcontinental anaesthesia. The clinical performance of hypnosis control was the efficacy to maintain bispectral index (BIS) at 45: 'excellent', 'good', 'poor', and 'inadequate' control represented BIS values within 10, from 11 to 20, from 21 to 30, or >30% from target. The clinical performance of analgesia was the efficacy to maintain Analgoscore values at 0 (-9 to 9); -3 to +3 representing 'excellent' pain control, -3 to -6 and +3 to +6 representing 'good' pain control, and -6 to -9 and +6 to +9 representing 'insufficient' pain control. The controller performance was evaluated using Varvel parameters. RESULTS: Transcontinental anaesthesia was successful in all 20 consecutive patients. The clinical performance of hypnosis showed an 'excellent and good' control for 69% of maintenance time, and the controller performance showed an average global performance index of 57. The clinical performance of analgesia was 'excellent and good' for 92% of maintenance time, and the controller performance showed a global performance index of 1118. CONCLUSIONS: Transcontinental anaesthesia is feasible; control of anaesthesia shows good performance indexes. Clinical registration number NCT01331096.

Perfusión intravenosa de remifentanilo controlada por ordenador: efectos, consumo, concentración efectiva / Intravenous infusion of remifentanil computer controlled: effects, consumption, effective concentration

Introducción: El objetivo fue comprobar si los sistemas de perfusión guiados por ordenador TCI (Target Control Infusion) estimando concentraciones plasmáticas (Cp), modulan condiciones hemodinámicas, consumo de remifentanil y concentraciones sitio efecto (Ce), en colecistectomía videolaparoscópica (CVL). Material y Métodos: Estudio clínico prospectivo, aleatorizado en pacientes ASA I, dos grupos: GRUPO PC (n = 12) remifentanil 0.5 mcg x kg-1 x min-1 y GRUPO TCI (n = 12) TCI remifentanil Cp 4 ng x ml-1 (Modelo Minto, Ke sub 0 0,595/min). Ambas perfusiones disminuidas 50% posintubación. Se registraron Tensión Arterial Sistólica (TAS), Tensión Arterial Diastólica (TAD) y Frecuencia Cardíaca (FC), remifentanil consumido y Ce, basal, posintubación, posincisión y finalización cirugía. Resultados: Sin diferencias entre grupos variables antropométricas, tiempos quirúrgico y de anestesia. Se halló diferencia G PC vs G TCI en FC (X ± de) posintubación 63,2 ± 12,2 vs 76,6 ± 13 (p = 0,014). Dentro grupos, G PC posintubación TAS 96,9 ± 18,5 (p = 0,0009), TAD 57,7 ± 15,2 (p = 0,0006) y FC 63,2 ± 12,2 (p = 0,010). Consumo de remifentanil G PC vs G TCI posintubación 216,2 ± 91,6 vs 102,4 ± 14,8 (p < 0,0001), posincisión 381,4 ± 185,4 vs 184,1 ± 39,6 (p = 0,0002) y fin de cirugía 2310 ± 912,8 vs 1642,4 ± 607,8 (p = ,028). Ce remifentanil posintubación 7,4 ± 1,6 vs 3,6 ± 0,2 (p < 0,0001), posincisión 6,1 ± 1,7 vs 2,2 ± 0,3 (p < 0,0001). Hipotensión G PC posintubación (50% p < 0,007), posincisión (33,3% p < 0,047), necesidad de efedrina dos pacientes G PC. Conclusión: La perfusión de remifentanil controlada por ordenador Cp de 4 ng/ml produjo en nuestro grupo de pacientes mejores condiciones hemodinámicas durante el intraoperatorio, comparada con perfusión continua de 0.5 mcg x kg-1 x min-1, en CVL. La mejoría se atribuiría a la adecuada concentración de remifentanil en sitio de efecto, permitiendo además disminuir el consumo de la droga.

[Effect of pediatric TCI system for propofol plus remifentanil in pediatric short-duration surgery with laryngeal mask airway anesthesia].

OBJECTIVE: To study the effect of a pediatric TCI patent system for propofol plus remifentanil in pediatric short-duration surgery with laryngeal mask airway (LMA) anesthesia. METHODS: A total of 120 pediatric patients underwent short-duration elective surgery, aged 3 - 9 years old, weighted 13 - 26 kg, ASAI grade, were randomly divided into 3 groups (n = 40 each). The propofol concentrations of effect compartment were set at 2 µg/ml in Group A, 3 µg/ml in Group B and 4 µg/ml in Group C. The remifentanil initial concentration of plasma compartment was 2 ng/ml and increased stepwise by 0.5 ng/ml until a successful insertion of LMA. The remifentanil concentration was recorded when LMA was successfully inserted and the cases were numerated at the each remifentanil concentration. Heart rate (HR), mean arterial pressure (MAP), BIS (bispectral index) values and postoperative adverse events were also recorded at the time points of pre-induction (T0), 2 min post-remifentanil TCI (T1), LMA insertion (T2), skin incision (T3), 5 min post-skin incision (T4), 10 min post-skin incision, (T5) and beginning surgery (T6). RESULTS: The satisfactory ratios of a successful insertion of LMA were highest in remifentanil 3.0 ng/ml (AR subgroup), 2.5 ng/ml (BR subgroup) and 2.0 ng/ml (CR subgroup) respectively. The laryngeal mask satisfactory ratio was high in BR subgroup (P < 0.05). There were significantly differences of T1-T5 values of HR, MAP and BIS in AR and CR subgroups (P < 0.05), but not in BR subgroup. The above-mentioned monitoring indices at T2 in AR subgroup and T3 in CR subgroup were significantly higher than those in BR subgroup. There were more adverse reactions in CR and AR subgroups versus BR subgroup (P < 0.05). CONCLUSION: The patented system for propofol 3 µg/ml effect compartment concentration plus remifentanil 2.5 ng/ml plasma concentration TCI displays stable hemodynamics, less stress, fewer complications and better clinical outcomes in pediatric short-duration surgery with LMA anesthesia.

Airway catastrophes.

PURPOSE OF REVIEW: The article reviews the epidemiology of airway injuries, airway anatomy, techniques for airway management, helpful pharmacologic adjuncts and finally alternatives to airway manipulation. RECENT FINDINGS: Principles of airway management including the maintenance of spontaneous ventilation and careful and adequate preparation for an alternative plan will always be important. Advances in pharmacologic agents provide a safer, more controlled environment through which the patient's compromised airway can be controlled. Recent publications add to the evidence that alternative methods of oxygenation and ventilation such as cardiopulmonary bypass can be used successfully to treat patients with catastrophic airway injuries. SUMMARY: Trauma to the airway, either blunt or penetrating or iatrogenic, can result in significant patient morbidity and mortality. Although, relatively rare, if we practice long enough, each of us will encounter such a patient. The anesthesiologist must be familiar with airway anatomy and the location of injury for successful treatment. Along with airway injuries, associated injuries are common and often complicate definitive airway treatment. Modern anesthetic medications such as dexmedetomidine and proven techniques such as awake fiberoptic intubation can be used to safely treat these difficult patients. Alternative therapies such as cricothyroidotomy and cardiopulmonary bypass should be available if first-line therapies fail to secure an injured airway.

Comparison of spectral entropy and bispectral index electroencephalography in coronary artery bypass graft surgery.

OBJECTIVE: The study's aim was to compare response entropy (RE) and state entropy (SE) with bispectral index (BIS) electroencephalography (EEG) as an alternative cerebral monitoring tool in patients scheduled for coronary artery bypass graft surgery. DESIGN: Prospective, observational single-center study. SETTING: University hospital. PARTICIPANTS: Thirty patients undergoing coronary artery bypass graft surgery receiving remifentanil-propofol anesthesia. INTERVENTIONS: Surgery was performed with cardiopulmonary bypass (CPB) and cardiac arrest in 15 patients, with CPB without cardiac arrest in 9 patients and without CPB in 6 patients. MEASUREMENTS AND MAIN RESULTS: RE, SE, BIS, burst suppression ratio (BSR), and frontal electromyography (f-EMG) were detected simultaneously. RE and SE compared favorably with BIS and their correlations were strong (r(2) = 0.6, r(2) = 0.55, respectively). The mean bias of RE and BIS was -1.8, but limits of agreement were high (+20.5/-24.1). RE and SE tended to be lower than the BIS values in the CPB subgroups. The detection of BSR was similar with RE and SE and the BIS. A strong correlation existed between BIS and f-EMG (r(2) = 0.62) in contrast to RE (r(2) = 0.45) and SE (r(2) =0.39). BIS monitoring was significantly more disturbed than RE and SE with 9.1% +/-10.9% and 0.1% +/- 0.2% of the total anesthesia time, respectively. Neither implicit nor explicit memory was shown. CONCLUSION: RE and SE are comparable with the BIS but showed significantly less interference from f-EMG and superior resistance against artifacts. Thus, spectral entropy is more suitable than the BIS during propofol-remifentanil anesthesia in cardiac surgery patients.