Comparisons of the efficiency of respiratory rate monitoring devices and acoustic respiratory sound during endoscopic submucosal dissection.

During moderate sedation for gastrointestinal endoscopic submucosal dissection (ESD), monitoring of ventilatory function is recommended. We compared the following techniques of respiratory rate (RR) measurement with respiratory sound (RRa): capnography (RRc), thoracic impedance (RRi), and plethysmograph (RRp). This study enrolled patients aged ≥ 20 years who underwent esophageal (n = 19) and colorectal (n = 5) ESDs. RRc, RRi, RRp, and RRa were measured by Capnostream™ 20P, BSM-2300, Nellcor™ PM1000N, and Radical-7®, respectively. In total, 413 RR data were collected from the esophageal ESD group and 114 RR data were collected from the colorectal ESD group. Compared with RRa during colorectal ESD, that during esophageal ESD had larger bias [95% limit of agreement (LOA)] with RRc [1.9 (- 11.0-14.8) vs. - 0.4 (- 2.9-2.2)], RRi [9.4 (- 16.8-9.4) vs. - 1.5 (- 12.0-8.9)], and RRp [0.3 (- 5.7-6.4) vs. 0.2 (- 3.2-3.6)]. Of the correct RR values displayed during esophageal ESD, > 90% were measured as RRa and RRp. Moreover, RRc was a useful parameter during colorectal ESD. To maximize patient safety during ESD under sedation, endoscopists and medical staff should know the feature and principle of the devices used for RR measurement. During esophageal ESD, RRa and RRp may be a good parameter to detect bradypnea or apnea. RRc, RRa and RRp are useful for reliable during colorectal ESD.Trial registration UMIN-CTR (UMIN000025421).

Forehead Regional Oxygen Saturation (rSO2)-Related Ear-Level Arterial Pressure and Lower Thigh rSO2 in the Steep Trendelenburg Position with CO2 Pneumoperitoneum and the Beach Chair Position.

Introduction Regional oxygen saturation (rSO2) reflects tissue perfusion. This observational study aimed to examine the change in the forehead and lower thigh rSO2 associated with intraoperative posture, anesthesia regimen, or mean arterial pressure (mAP) at heart and external auditory meatus (ear) levels. Methods Patients undergoing robot-assisted laparoscopic radical prostatectomy in the Trendelenburg position at 30° with pneumoperitoneum (TPP) or arthroscopic shoulder surgery in the beach chair position at 70° (BCP) under desflurane-remifentanil (D/R) or propofol-remifentanil (P/R) anesthesia were examined. Bilateral forehead and lower thigh rSO2 values and mean radial artery pressure were measured simultaneously at heart and ear levels. Results In TPP, there were no differences under anesthesia regimens in the forehead or lower thigh rSO2change, although one patient with an absolute lower thigh rSO2 of ≤50% in the lithotomy position complained of transient limb pain. No correlation was observed between rSO2 and mAP. In BCP, forehead rSO2 decreased and lower thigh rSO2 increased under either of the anesthesia regimens. The coefficient of correlation between forehead rSO2 andheart-level and ear-level mAP was 0.341 and 0.236, respectively. Conclusions There were no differences under anesthesia regimens in the changes of forehead rSO2 and lower thigh rSO2. In TPP, significant changes in forehead rSO2 and lower thigh rSO2 were not observed. Monitoring lower thigh rSO2 might be useful for preventing lower extremity pain. In BCP, forehead rSO2 decreased and lower thigh rSO2 increased from the supine position to the BCP. To prevent brain damage, anesthesiologists should pay attention to heart- and ear-level mAP.

Comparison of Nellcor™ PM1000N and Masimo Radical-7® for detecting apnea in volunteers.

PURPOSE: Although capnography is considered the gold standard for monitoring of ventilation, it may not work accurately in some situations. We compared the performance of two non-invasive continuous respiratory rate (RR) monitors that are alternatives for the detection of respiratory depression. METHODS: Fifty healthy volunteers ≥20 years old were enrolled in this study. After monitoring of the volunteers was started by the Masimo Radical-7® and Nellcor™ PM1000N, they breathed at the rate of 12 breaths/min for 3 min and then stopped breathing. As soon as the apnea alarm of either monitor went off, breathing was resumed at the same rate. This entire procedure was repeated three times. The data collected every 30 s included the RR, pulse rate (PR) and oxygen saturation (SpO2). The times of alarm on, alarm off and reappearance of RR on the monitor screens were also recorded. RESULTS: The biases of the RR, PR and SpO2 measurements from the two monitors were 0.5, 0.2 and -0.4, respectively. Of 143 procedures that stopped breathing for more than 30 s, 114 and 15 alarms were shown by the Masimo Radical-7® and Nellcor™ PM-1000N monitors, respectively. Most alarms of the Nellcor™ PM1000N followed from SpO2 <90%. Conversely, most alarms of the Masimo Radical-7® were caused by RR <10 breaths/min. Times to alarm on, alarm off and display of RR measured by the Masimo Radical-7® monitor were significantly shorter than the Nellcor™ PM-1000N monitor. CONCLUSIONS: The Masimo Radical-7® monitor provides better detection of apnea in volunteers than the Nellcor™ PM-1000N.

Is the Ambu aScope 3 Slim single-use fiberscope equally efficient compared with a conventional bronchoscope for management of the difficult airway?

STUDY OBJECTIVE: The study objective was to evaluate whether the single-use fiberoptic bronchoscope (FOB), Ambu aScope 3 Slim, was equally efficient compared with the conventional reusable FOB, Olympus LF-GP, for nasal fiberoptic intubation in a manikin. DESIGN: A randomized crossed-over study. SETTING: The postanesthesia care unit of Tokyo Women's Medical University Hospital. SUBJECTS: Twenty anesthesiologists who have experienced >50 one-lung ventilation thoracic surgery procedures were invited to participate in this study. INTERVENTIONS: A 6.5-mm internal diameter cuffed endotracheal tube (ET) was inserted into the manikin under Ambu aScope 3 Slim (group A) or Olympus LF-GP (group C) guidance. MEASUREMENTS: The following time parameters from the beginning of FOB insertion through a nostril were compared between groups: until vocal cord visualization (T1); visualization of the carina (T2); and proper ET placement, as confirmed by the distance of the ET tip to carina (T3). MAIN RESULTS: Mean (SD) T1 in group A and group C were 20 seconds (17 seconds) and 14 seconds (12 seconds), respectively (P= .1050). Mean (SD) T2 in group A and group C were 40 seconds (29 seconds) and 25 seconds (15 seconds), respectively (P= .0287). Mean (SD) T3 in group A and group C were 70 seconds (33 seconds) and 50 seconds (22 seconds), respectively (P= .0098). One case in group A had failed intubation CONCLUSIONS: The Ambu aScope 3 Slim required more time to intubate than the conventional reusable FOB. It requires more rigidity, similar to the conventional FOB for management of the difficult airway.

Challenge to pediatric anatomical variation : Can we draw the ideal line on the pediatric I-gel?

OBJECTIVE: I-gel is a noncuff type of laryngeal airway mask. No horizontal line has yet been determined as an ideal position for pediatric sizes because of the variability in length of the oropharyngeal-laryngeal arch in children. We investigated whether there is a correlation between insertion length and patient body weight or height for the pediatric I-gel sizes from 1.5 to 2.5. METHODS: With parental informed consent, we planned to maintain the airway of 130 children aged from 7 months to 13 years by using the I-gel device under general anesthesia. The following two parameters were evaluated: (1) distance between the teeth and the connector wing; (2) insertion length (distance from the distal end of the gastric tube to the teeth). Size selection was determined on the basis of patients' body weight. We identified the relationship between each parameter and height or weight. RESULTS: Average insertion length became gradually longer with increasing height and weight. Spearman's R between insertion length and height or weight was 0.8. There was more correlation with height than with weight in pediatric size 2.5. CONCLUSION: Results suggested that it is possible to draw an ideal line on the I-gel with sizes 1.5 and 2 only.

Ultrasound versus anatomical landmarks for caudal epidural anesthesia in pediatric patients.

BACKGROUND: Caudal block is easily performed because the landmarks are superficial. However, the sacral hiatus is small and shallow in pediatric patients. In the present study, we evaluated under general anesthesia whether the distance between the bilateral superolateral sacral crests increased with growth, whether an equilateral triangle was formed between the apex of the sacral hiatus and the bilateral superolateral sacral crests, and whether expansion of the epidural space could be confirmed by ultrasound. METHODS: This prospective observational study included 282 children who were ASA I-II. Under general anesthesia, each patient was placed in the lateral bent knees position, and the attending anesthesiologist drew an equilateral triangle and measured the distance between the bilateral superolateral sacral crests along a line forming the base of the triangle. Then the sacral hiatus was identified by ultrasound. Differences of the distance between the anatomical landmarks measured by the anesthetist and by ultrasound were evaluated. RESULTS: Two patients were excluded because the superolateral sacral crests and sacral hiatus could not be palpated. The base of the triangle increased in proportion to age up to 10 years old, with a significant correlation between age and the length of the base (Spearman's r value = 0.97). The triangle was not an equilateral triangle under 7 years old. The sacral hiatus could be identified by ultrasound and we could confirm expansion of the epidural space in all patients. CONCLUSION: We observed a correlation between age and the length of the triangle base in children under 10 years old. Although detection of the anatomical landmarks by palpation differed from identification by ultrasound in pediatric patients, performing ultrasound is important. Epinephrine should be added to the anesthetic to avoid complications. TRIAL REGISTRATION: Current Controlled Trials UMIN000017898 . Registered 14 June 2015. Date of protocol fixation was 1(st) December, 2008 and Anticipated trial start date was 5(th) January, 2009.

Adenosine triphosphate bioluminescence assay for monitoring contamination of the working environment of anaesthetists and cleanliness of the operating room.

Anaesthetists possibly contribute to the spread of infections during anaesthesia. The adenosine triphosphate (ATP) bioluminescence assay is an easy-to-perform, on-the-spot assay that provides objective data; therefore, using the LuciPac®Pen and the Lumitester PD-20®System, we assessed contamination of the working environment of anaesthetists before and after surgery as well as their hands at the time of each procedure during induction and extubation. Similarly, cleanliness of the operating room was evaluated using this assay to determine whether it is useful to assess the effectiveness of the routine cleaning protocols followed after surgery. ATP concentrations in the working environment of anaesthetists and their hands increased during surgery. In addition, ATP concentrations within the working environment decreased after routine cleaning with ethanol or accelerated hydrogen peroxide; however, there were no differences in the number of sites with ATP concentrations >500 relative light units before and after cleaning. This method is useful to evaluate contamination of the working environment of anaesthetists; nevertheless, it is prudent to evaluate the effectiveness of routine cleaning protocols because ATP bioluminescence assays are influenced by the use of various disinfectants at varying concentrations.

A randomised double-blind crossover trial of the potential analgesic effect of a transdermal nicotine patch in non-smokers based on objective and subjective assessment.

OBJECTIVE: The results of studies of the analgesic effect of nicotine in humans are complex because these studies have included smokers with variable smoking histories. We investigated whether the use of a 17.5 mg transdermal nicotine (TDN) patch decreased the magnitude of pressure pain on the hands of healthy non-smoking volunteers. DESIGN: This was a randomised double-blind crossover trial. A TDN patch or placebo (drug-free bandage) was applied randomly on the anterior chest of non-smoking volunteers 1 h before the experiments. We measured minimum perceived current and pain threshold on the right hand and then evaluated the magnitude of pressure pain by using the Pain Vision PS-2100 (Nipro Co., Osaka, Japan) which helps in objective quantitative assessment of pain magnitude. After estimating minimum perceived current, pressure pain was produced using a combination of 100-g discs and a rod. The rod and the discs weighing 0 (no disc), 200 (two discs), 400 (four discs), 200 (two discs) and 0 g (no disc) were placed consecutively in this order on the right hand and pain threshold was measured. At the same time, volunteers were asked to rate pain on a numerical rating scale (NRS). Minimum perceived current is the current at which the volunteer perceives the first sensation on applying gradually increasing pulsed current. Pain threshold is the compatible electrode current at which the volunteer feels the intensity of pressure pain. Pain degree is calculated as (pain threshold-minimum perceived current)/minimum perceived current × 100. PARTICIPANTS: Forty non-smoking volunteers were enrolled in this study. RESULTS: No significant differences between groups were observed in minimum perceived current, pain threshold, pain degree or NRS. Of the volunteers who received the nicotine patch, four became anorexic and nauseated and two required anti-emetics. CONCLUSION: The nicotine patch had no analgesic effect in non-smoking volunteers.

[Reliability of propofol target-controlled infusion in elderly patients].

BACKGROUND: Propofol target-controlled infusion (TCI) is now commonly used for the induction and maintenance of anesthesia. In this study, we measured the propofol plasma concentrations of elderly patients to evaluate our hypothesis that propofol TCI is reliable for use in elderly patients. METHODS: We measured plasma concentrations of propofol in 10 elderly patients undergoing elective general anesthesia. Propofol TCI was commenced at a target plasma concentration of 3 microg x ml(-1) using a TCI pump. The target concentration was kept at 3 microg x ml(-1) for 2-3 hours. Arterial blood samples were drawn for measurement of the propofol plasma-concentration analysis at 30, 60, 90, 120 and 180 minutes after the induction of anesthesia, and at the emergence from anesthesia. RESULTS: The measured plasma concentrations of propofol were not significantly different from the target plasma concentrations. The mean estimated and measured plasma concentrations at emergence were at about 1 microg x ml(-1), respectively. CONCLUSIONS: We concluded that propofol TCI is a reliable method for maintaining anesthesia even in elderly patients, whereas the individual differences of the elderly patients was greater than those obtained from normal patients.

[Reliability of propofol target-controlled infusion in obese patients].

BACKGROUND: Propofol target-controlled infusion (TCI) is now commonly used for induction and maintenance of anesthesia. In this study, we measured the propofol plasma concentrations in obese patients in order to test our hypothesis that propofol TCI is reliable for use in obese patients. METHODS: We measured plasma concentrations of propofol in 10 obese patients undergoing elective general anesthesia. Propofol TCI was commenced at a target plasma concentration of 4microg x ml(-1) using a TCI pump. The target concentration was kept at 4microg x ml(-1) for at least 3 hours. Arterial blood samples were drawn for measurement of the propofol plasma-concentration analysis at 30, 60, 90, 120 and 180 minutes after the induction of anesthesia, and at the emergence from anesthesia. RESULTS: The measured plasma concentrations of the drug were not significantly different from the target plasma concentrations and they showed no tendency to increase during the 3 hours of anesthesia. The measured plasma concentration at emergence was lower than the estimated value. CONCLUSIONS: We conclude that propofol TCI is a reliable method for maintaining anesthesia even in obese patients. At emergence, however, the data suggested that the plasma concentrations might be lower than the estimated values in obese patients.

[Evaluation of target-controlled infusion for propofol in patients with chronic renal failure undergoing living-related renal transplantation].

BACKGROUND: As we have no information whether target-controlled infusion (TCI) for propofol, using pharmacokinetic parameters obtained without chronic renal failure, is available to estimate the drug concentration, we examined the blood concentration of propofol on the patients with chronic renal failure to evaluate the reliability of TCI of propofol. METHODS: Ten patients with chronic renal failure undergoing hemodialysis, from 20 to 60 years of age, were scheduled for living-related renal transplantation. Propofol was administrated with our TCI system at the target blood concentration of 4 microg x ml(-1) for three hours. Blood samples were obtained at 30, 60, 90, 120, and 180 minutes after starting propofol delivery, and at the emergence from anesthesia to measure propofol concentration. RESULTS: There was no tendency of increasing the drug concentration in proportion to the time of propofol infusion. As for the concentration at emergence, mean estimated concentration of propofol was 1.6 mg x ml(-1), showing a good correlation between measured and estimated concentrations. CONCLUSION: TCI system for propofol provided a good estimation of the blood concentration of propofol in patients with chronic renal failure undergoing living-related renal transplantation.

Individual effect-site concentrations of propofol are similar at loss of consciousness and at awakening.

Reported effect-site concentrations of propofol at loss of consciousness and recovery of consciousness vary widely. Thus, no single concentration based on a population average will prove optimal for individual patients. We therefore tested the hypothesis that individual propofol effect-site concentrations at loss and return of consciousness are similar. Propofol effect-site concentrations at loss and recovery of consciousness were estimated with a target-control infusion system in 20 adults. Propofol effect-site concentrations were gradually increased until the volunteers lost consciousness (no response to verbal stimuli); unconsciousness was maintained for 15 min, and the volunteers were then awakened. This protocol was repeated three times in each volunteer. Our major outcomes were the concentration producing unconsciousness and the relationship between the estimated effect-site concentrations at loss and recovery of consciousness. The target effect-site propofol concentration was 2.0 +/- 0.9 at loss of consciousness and 1.8 +/- 0.7 at return of consciousness (P <0.001). The average difference between individual effect-site concentrations at return and loss of consciousness was only 0.17 +/- 0.32 microg/mL (95% confidence interval for the difference 0.09-0.25 microg/mL). Our results thus suggest that individual titration to loss of consciousness is an alternative to dosing propofol on the basis of average population requirements.

[Comparison of requirement for postoperative analgesics after inhalation and total intravenous anesthesia].

BACKGROUND: We evaluated the requirement for postoperative analgesics in 88 patients undergoing abdominal total hysterectomy with inhalation anesthesia or with total intravenous anesthesia. METHODS: Anesthesia was induced in the inhalation anesthesia (GOS, n = 52) group with propofol and fentanyl, and maintained with sevoflurane, nitrous oxide balanced with oxygen, and additional administrations of fentanyl up to 0.2 mg in total. The patients in the total intravenous anesthesia (TIVA, n = 36) group were managed with target controlled infusion for propofol and intermittent administration of fentanyl. Effect site concentrations of fentanyl at the end of surgery were calculated using a pharmacokinetic-pharmacodynamic model. We divided the postoperative time course and evaluated the types, dosages, and prescription times of postoperative analgesics in each. RESULTS: Both total dosage and effect-site concentration of fentanyl were higher in the TIVA group than in the GOS group, and total prescription time in the TIVA group was significantly less during the 24 hrs after the operation. Supplemental prescription intervals of buprenorphine were significantly less in the TIVA group. Since administration of fentanyl during operation was adequate, patients in the TIVA group were considered to be in a sufficient analgesic state at the end of operation. CONCLUSIONS: The postoperative pain can be reduced with TIVA.

Effect-site concentration of propofol for recovery of consciousness is virtually independent of fentanyl effect-site concentration.

UNLABELLED: Fentanyl reduces the amount of propofol necessary to prevent responses to surgical stimuli. However, opioids have relatively little effect on consciousness. We, therefore, tested the hypothesis that fentanyl minimally alters the effect-site concentration of propofol associated with awakening. Fifty women having gynecologic laparotomy with propofol anesthesia were randomly allocated into the following target effect-site fentanyl concentrations: 0.8, 1.0, 1.4, 2.0, and 3.0 ng/mL. Fentanyl was continued at the designated rate through the initial postoperative phase. The propofol effect-site concentration associated with eye opening in response to verbal command was regarded as the awakening concentration. The estimated propofol effect-site concentrations at awakening did not differ significantly among the groups and were 1.9 +/- 0.5 micro g/mL with a fentanyl effect-site concentration of 0.8 ng/mL; 1.6 +/- 0.4 micro g/mL with 1.0 ng/mL of fentanyl; 1.6 +/- 0.2 micro g/mL with 1.4 ng/mL of fentanyl; 1.7 +/- 0.4 micro g/mL with 2.0 ng/mL of fentanyl; and 1.6 +/- 0.34 micro g/mL with 3.0 ng/mL of fentanyl (mean +/- SD). Seventy percent of the subjects in the 0.8 ng/mL fentanyl group spontaneously complained of pain, whereas none of the patients in the 2 or 3 ng/mL groups did. Five (56%) of 9 women in the 3 ng/mL group had a postoperative respiratory rate <6 breaths/min. Heart rate in one of these women decreased to <40 bpm. These data suggest that the optimal fentanyl effect-site concentration in patients recovering from gynecologic laparoscopy is between 1.4 and 2.0 ng/mL. IMPLICATIONS: The effect-site concentration for propofol at awakening was virtually independent of the fentanyl effect-site concentration over the range of 0.8 to 3.0 ng/mL; however, 0.8 ng/mL of fentanyl was associated with inadequate postoperative analgesia, and 3.0 ng/mL of fentanyl was associated with respiratory toxicity. The optimal postoperative fentanyl effect-site concentration during recovery from propofol general anesthesia for laparotomy thus appears to be near 2 ng/mL.

[Diagnosis of the autonomic nervous function during sedation by peripheral blood flow and psychogenic perspiration].

BACKGROUND: Pain induces a variety of physiological responses, many of which are mediated by the sympathetic nervous system. Among these are a reduction in peripheral blood flow and evaporative cutaneous water loss (sweating). We therefore tested the hypothesis that adequate sedation obliterates the normal pain-induced reduction in peripheral blood flow and an increase in evaporative water loss. METHODS: We studied eight volunteers. Two different painful stimuli were randomly applied: 1) electrical pulp stimulation (200 microamperes) and 2) electrical pain stimulation on the right upper thigh (80 mA). Conscious sedating was controlled by propofol infusion titrated to a Bispectral Index near 80, or near 60. RESULTS: At each stimulation, peripheral blood flow detected by laser Doppler decreased without any relation to the level of consciousness (by Bispectral Index). On the other hand, although the psychogenic perspiration rate increased significantly at alert level, during BIS 80 or 60 level, the increase was not significant. CONCLUSION: Peripheral blood flow reacts most to pain stimulation during intravenous sedation.

[Two cases of intraoperative awareness during intravenous anesthesia with propofol in morbidly obese patients].

We experienced two cases of intraoperative awareness during intravenous anesthesia with propofol and fentanyl in morbidly obese patients. The rates of propofol infusion were calculated according to the adjusted body weights, or reduced intentionally as obese patients are generally believed to require lower doses of propofol compared with non-obese patients. Our postoperative analysis by simulations using the anesthesia records showed that, when the simulation was based on real body weight, the blood/effect-site concentrations of propofol in both patients would have been below the necessary levels to keep the patients unconscious during the operation, but when the simulation was based on adjusted body weight, those concentrations might have been within the necessary range to maintain an adequate hypnotic level. We propose that the rate of propofol infusion should be the same in obese and non-obese patients and should be calculated according to the real body weight not to the adjusted body weight.