Hiroko Iwakiri’s research while affiliated with Tokyo Women's Medical University and other places

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).

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.

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.

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.

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.

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.

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.

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. 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. Forty non-smoking volunteers were enrolled in this study. 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. The nicotine patch had no analgesic effect in non-smoking volunteers.