磯野 史朗

PURPOSE: Nurses routinely assess respiration of hospitalized children; however, respiratory rate measurements are technically difficult due to rapid and small chest wall movements. The aim of this study is to reveal the respiratory status of small children undergoing minor surgery with load cells placed under the bed legs, and to test the hypothesis that respiratory rate (primary variable) is slower immediately after arrival to the ward and recovers in 2 h. METHODS: Continuous recordings of the load cell signals were performed and stable respiratory waves within the 10 discriminative perioperative timepoints were used for respiratory rate measurements. Apnea frequencies were calculated at pre and postoperative nights and 2 h immediately after returning to the ward after surgery. RESULTS: Continuous recordings of the load cell signals were successfully performed in 18 children (13 to 119 months). Respiratory waves were appraisable for more than 70% of nighttime period and 40% of immediate postoperative period. There were no statistically significant differences of respiratory rate in any timepoint comparisons (p = 0.448), thereby not supporting the study hypothesis. Respiratory rates changed more than 5 breaths per minute postoperatively in 5 out of 18 children (28%) while doses of fentanyl alone did not explain the changes. Apnea frequencies significantly decreased 2 h immediately after returning to the ward and during the operative night compared to the preoperative night. CONCLUSION: Respiratory signal extracted from load cell sensors under the bed legs successfully revealed various postoperative respiratory pattern change in small children undergoing minor surgery. CLINICAL TRAIL REGISTRATION: UMIN (University Hospital Information Network) Clinical Registry: UMIN000045579 ( https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000052039 ).

BACKGROUND: Activity levels of patients often scaled as performance status (PS) is the most important scale in oncology populations for treatment decisions and prognosis prediction. However, it is usually subjective and open to bias. The need for more objective and reliable assessment tools is mandatory for safe and effective oncology practice. To investigate the reliability of continuous vital and activity evaluation monitored by bed sensor systems in advanced cancer patients, we conducted a cohort pilot study in hospitalized cancer patients under several PS conditions. METHODS: Adult patients, either admitted in the oncology department or palliative care unit, were enrolled in the study after written informed consent. Continuous monitoring for 48 hours from the first night of admission was performed without any restrictions on the patients. Calculated acceleration of movement [activity index (ACI)], % time on bed and number of bed leave in an 8-hour period, as well as other vital signs were monitored. Analysis focused on change of PS to 3, a standard cut-off for curative cancer treatment and PS4, vital for prognosis assessment. RESULTS: Nineteen patients' data were analyzed. In PS4 palliative care patients, ACI was significantly low and % time on bed was high from PS3 palliative care patients. Instabilities of respiratory rate, respiratory tidal weight and heart rate were significantly higher in palliative care patients (PS3, PS4) compared with oncology patients (PS1, PS2). CONCLUSIONS: This result, though in need of larger trials, shows possibilities for continuous objective monitoring of patients in bed for PS assessment in advanced cancer patients.

PURPOSE: Stridor during emergence from anesthesia is not rare in children managed with supraglottic airway (SGA). However, we know little about the mechanisms of stridor and behavior of the vocal cords (VC). This study aimed to clarify patterns of VC movement and laryngeal airway maintenance function during recovery from anesthesia in children with SGA. METHODS: This is a secondary analysis of data collected from an observational study involving 27 anesthetized children. Using a multi-panel recording system, endoscopic VC image, vital sign monitor, multi-channel tracings of respiratory variables and respiratory sound and patient's view were simultaneously captured in one monitor. Inspiratory and expiratory VC angles formed by lines connecting anterior and posterior commissures were measured at the first spontaneous breath and the breath one minute after the first breath. VC narrowing and dilation were assessed by differences of VC angles. RESULTS: Inspiratory VC narrowing (median (IQR): 5.3 (2.7, 9.1) degree at the first breath) and dilation (- 2.7 (- 3.8, - 1.7) degree at the first breath) were observed in 15 and 12 out of 27 children, respectively. The former group achieved greater tidal volume compared to the latter in one minute. Five children (19%) temporarily developed stridor-like sound from outside with inspiratory VC narrowing. The stridor-like sound was captured by microphones attached to the neck and anesthesia circuit, but was not evident from the chest. CONCLUSION: Laryngeal narrowing occurs in half of the children with SGA during emergence from anesthesia, and temporal stridor-like sound is relatively common. CLINICAL TRIAL REGISTRATION: UMIN (University Hospital Information Network) Clinical Registry: UMIN000025058 ( https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000028697 ).

Development of reliable non-contact unrestrained respiratory monitoring is capable of augmenting the safety of hospitalized patients in the recovery phase. We previously discovered respiratory-related centroid shifts along the long axis of the bed with load cells under the bed legs (bed sensor system: BSS). This prospective exploratory observational study examined whether non-contact measurements of respiratory-related tidal centroid shift amplitude (TA-BSS: primary variable) and respiratory rate (RR-BSS: secondary variable) were correlated with tidal volume (TV-PN) and respiratory rate (RR-PN), respectively measured by pneumotachograph in 14 ICU patients under mechanical ventilation. Among the 10-minute average data automatically obtained for a 48-hour period, 14 data were randomly selected from each patient. Successfully and evenly selected 196 data points for each variable were used for the purpose of this study. A good agreement between TA-BSS and TV-PN (Pearson's r = 0.669) and an excellent agreement between RR-BSS and RR-PN (r = 0.982) were observed. Estimated minute ventilatory volume as 3.86*TA-BSS*RR-BSS (MV-BSS) was found to be in very good agreement with true minute volume (MV-PN) (r = 0.836). Although Bland-Altman analysis evidenced accuracy of MV-BSS by a small insignificant fixed bias (-0.02 liter/min), a significant proportional bias of MV-BSS (r = -0.664) appeared to produce larger precision (1.9 liter/min) of MV-BSS. We conclude that contact-free unconstraint respiratory monitoring with load cells under the bed legs may serve as a new clinical monitoring system, when improved.

Nasal pressure signal is commonly used to evaluate obstructive sleep apnea. This study aimed to assess its safety for respiratory monitoring during sedation. A total of 45 adult patients undergoing sedation with propofol and fentanyl for invasive endoscopic procedures were enrolled. While both nasal pressure and capnograph signals were continuously recorded, only the nasal pressure signal was displayed. The primary outcome was the incidence of oxygen desaturation below 90%. The secondary outcomes were the ability to predict the desaturation and incidence of harmful events and false alarms, defined as an apnea waveform lasting more than 3 min without desaturation. Of the 45 participants, 43 completed the study. At least one desaturation event occurred in 12 patients (27.9%; 95% confidence interval 15.3-43.7%). In these 12 patients, more than half of the desaturation events were predictable in 9 patients by capnography and 11 patients by nasal pressure monitoring (p = 0.59). In the 43 patients, false alarms were detected in 7 patients with capnography and 11 patients with nasal pressure monitoring (p = 0.427). Harmful events unrelated to nasal pressure monitoring occurred in 2 patients. Nasal pressure monitoring is safe and possibly useful for respiratory monitoring despite false alarms during sedation.

BACKGROUND: We aimed to identify the factors associated with postoperative pain, quality of life, and development of chronic pain after lung cancer surgery, including pain sensation threshold, fentanyl sensitivity, and surgical procedures. METHODS: We conducted a single-center prospective observational study involving lung cancer patients. Brief pain inventory, including nine items concerning pain and quality of life, was investigated at 1 week, 1 month, and 3 months postoperatively. Pain sensation threshold and fentanyl sensitivity were assessed preoperatively. RESULTS: Of the 146 patients who were enrolled, 100 who met our criteria were analyzed. Thoracoscopic surgery was performed in 42 patients and minimally invasive thoracotomy in 58 patients. Pain sensation threshold and fentanyl sensitivity were normally distributed among the patients and were not significantly associated with brief pain inventory scores at each postoperative time-point. The average pain score 1 week after the operation was significantly higher in the thoracotomy group than in the thoracoscopic surgery group (P<0.050). The worst pain scores did not differ between the groups at all the examination periods. Pain sensation threshold, fentanyl sensitivity, and surgical procedures were not related to the incidence of post-thoracotomy pain syndrome. CONCLUSIONS: Individual pain sensation threshold and fentanyl sensitivity were not associated with subjective postoperative pain score, quality of life score, or development of post-thoracotomy pain syndrome.

BACKGROUND Both excessive positive fluid balance and body weight increase after surgery are risk factors for poor postoperative outcomes. The use in clinical practice and the value of perioperative body weight measurements are unclear at present, possibly due to difficulty in measuring body weight in patients lying on the bed and insufficient clinical research. OBJECTIVES To investigate the relationship between intraoperative fluid balance and body weight change and perioperative nightly body weight change pattern throughout the hospital stay with contact-free unconstraint load cells placed under the bed legs. DESIGN Observational and exploratory study. SETTING A single university hospital. PATIENTS Twenty adult patients were undergoing elective abdominal surgery under general anaesthesia. MAIN OUTCOME MEASURES Body weight. RESULTS Immediately after surgery, body weight increased significantly by 2.7 ± 1.3 kg, equivalent to a 5% increase from the preoperative body weight. This increase was not correlated with (P = 0.178) the intraoperative fluid balance and was significantly greater than the intraoperative fluid balance 1.5 ± 0.4 kg (P &lt; 0.001). The body weight returned to the preoperative level on postoperative day (POD)3 and further significantly decreased to 97% of the preoperative body weight at POD6 (P &lt; 0.001). This physiological nocturnal weight loss pattern was maintained throughout hospitalisation except when fluid was infused. Compared with their preoperative status, patients stayed in bed longer with smaller body movements and left the bed less frequently during the daytime until POD3. Conversely, the patients had greater body movements in bed during the night leading to smaller diurnal variation in the body movements in bed after POD4. CONCLUSION Both perioperative fluid balance calculation and body weight measurement may have different but mutually complementary roles in perioperative managements. Postoperative fluid and nutrition management strategies are potentially new directions for treatment through continuous weight monitoring during the perioperative period. Trial registration : UMIN Clinical Trials Registry (UMIN000040164).

BACKGROUND: The low acceptance rate of continuous positive airway pressure therapy in postoperative patients with untreated obstructive sleep apnea (OSA) indicates the necessity for development of an alternative postoperative airway management strategy. The authors considered whether the combination of high-flow nasal cannula and upper-body elevation could improve postoperative OSA. METHODS: This nonblinded randomized crossover study performed at a single university hospital investigated the effect on a modified apnea hypopnea index, based exclusively on the airflow signal without arterial oxygen saturation criteria (flow-based apnea hypopnea index, primary outcome), of high-flow nasal cannula (20 l · min-1 with 40% oxygen concentration) with and without upper-body elevation in patients with moderate to severe OSA. Preoperative sleep studies were performed at home (control, no head-of-bed elevation) and in hospital (30-degree head-of-bed elevation). On the first and second postoperative nights, high-flow nasal cannula was applied with or without 30-degree head-of-bed elevation, assigned in random order to 23 eligible participants. RESULTS: Twenty-two of the 23 (96%) accepted high-flow nasal cannula. Four participants resigned from the study. Control flow-based apnea hypopnea index (mean ± SD, 60 ± 12 events · h-1; n = 19) was reduced by 15 (95% CI, 6 to 30) events · h-1 with head-of-bed elevation alone (P = 0.002), 10.9 (95% CI, 1 to 21) events · h-1 with high-flow nasal cannula alone (P = 0.028), and 23 (95% CI, 13 to 32) events · h-1 with combined head-of-bed elevation and high-flow nasal cannula (P < 0.001). Compared to sole high-flow nasal cannula, additional intervention with head-of-bed elevation significantly decreased flow-based apnea hypopnea index by 12 events · h-1 (95% CI, 2 to 21; P = 0.022). High-flow nasal cannula, alone or in combination with head-of-bed elevation, also improved overnight oxygenation. No harmful events were observed. CONCLUSIONS: The combination of high-flow nasal cannula and upper-body elevation reduced OSA severity and nocturnal hypoxemia, suggesting a role for it as an alternate postoperative airway management strategy.

BACKGROUND: Mask ventilation progressively improves after loss of consciousness during anesthesia induction possibly due to progression of muscle paralysis. This double-blinded randomized placebo-controlled study aimed to test a hypothesis that muscle paralysis improves mask ventilation during anesthesia induction. METHODS: Forty-four adults patients including moderate to severe obstructive sleep apnea undergoing scheduled surgeries under elective general anesthesia participated in this study. Randomly-determined test drug either rocuronium or saline was blinded to the patient and anesthesia provider. One-handed mask ventilation with an anesthesia ventilator providing a constant driving pressure and respiratory rate (15 breaths per minute) was performed during anesthesia induction, and changes of capnogram waveform and tidal volume were assessed for one minute. The needed breaths for achieving plateaued-capnogram (primary variable) within 15 consecutive breaths were compared between the test drugs. RESULTS: Measurements were successful in 38 participants. Twenty-one and seventeen patients were allocated into saline and rocuronium respectively. The number of breaths achieving plateaued capnogram did not differ between the saline (95% C.I.: 6.2 to 12.8 breaths) and rocuronium groups (95% C.I.: 5.6 to 12.7 breaths) (p = 0.779). Mean tidal volume changes from breath 1 was significantly greater in rocuronium group than saline group (95% C.I.: 0.56 to 0.99 versus 3.51 to 4.53 ml kg-IBW-1, p = 0.006). Significantly more patients in rocuronium group (94%) achieved tidal volume greater than 5 mg kg-ideal body weight-1 within one minute than those in saline group (62%) (p = 0.026). Presence of obstructive sleep apnea did not affect effectiveness of rocuronium for improvement of tidal volume during one-handed mask ventilation. CONCLUSIONS: Use of rocuronium facilitates tidal volume improvement during one-handed mask ventilation even in patients with moderate to severe obstructive sleep apnea. TRIAL REGISTRATION: The clinical trial was registered at (05/12/2013, UMIN000012495): https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000014515.

Some evidence suggests that both hypothermia and anesthesia can exert similar effects on metabolism and ventilation. This study examined the synergistic effects of anesthesia and hypothermia on ventilation in spontaneously breathing adult mice under three different conditions, that is, (1) pentobarbital group (n = 7) in which mice were anesthetized with intraperitoneal pentobarbital of 80 mg/kg, (2) sevoflurane-continued group (n = 7) in which mice were anesthetized with 1 MAC sevoflurane, and (3) sevoflurane-discontinued group (n = 7) in which sevoflurane was discontinued at a body temperature below 22˚C. We cooled mice in each group until breathing ceased and followed this with artificial rewarming while measuring changes in respiratory variables and heart rate. We found that the body temperature at which respiration arrested is much lower in the sevoflurane-discontinued group (13.8 ± 2.0˚C) than that in the sevoflurane-continued group (16.7 ± 1.2˚C) and the pentobarbital group (17.0 ± 1.4˚C). Upon rewarming, all animals in all three groups spontaneously recovered from respiratory arrest. There was a considerable difference in breathing patterns between sevoflurane-anesthetized mice and pentobarbital-anesthetized mice during progressive hypothermia in terms of changes in tidal volume and respiratory frequency. The changes in the respiratory pattern during rewarming are nearly mirrored images of the changes observed during cooling in all three groups. These observations indicate that adult mice are capable of autoresuscitation from hypothermic respiratory arrest and that anesthesia and hypothermia exert synergistic effects on the occurrence of respiratory arrest while the type of anesthetic affects the breathing pattern that occurs during progressive hypothermia leading to respiratory arrest.

BACKGROUND: Rapid emergence from general anaesthesia is desirable only if safety is not sacrificed. Mechanical hyperventilation during hypercapnia produced by carbon dioxide infusion into the inspired gas mixture or by rebreathing was reported to shorten emergence time from inhalation anaesthesia. OBJECTIVES: To test the hypothesis that hypercapnia produced by hypoventilation before desflurane cessation shortens emergence time from general anaesthesia (primary hypothesis) and reduces undesirable cardiorespiratory events. DESIGN: A single-blinded randomised controlled study. SETTING: A single university hospital. PATIENTS: Fifty adult patients undergoing elective abdominal surgery under general anaesthesia using desflurane inhalation and intra-operative epidural anaesthesia. INTERVENTION: The patients were randomly assigned to either the normocapnia or hypercapnia group. MAIN OUTCOME MEASURES: Emergence time from desflurane anaesthesia and comparison of the incidence of 11 predefined undesirable cardiorespiratory events during and after emergence from anaesthesia between the groups. RESULTS: Forty-six patients were included in the analysis. End-tidal carbon dioxide concentrations at cessation of desflurane were 35 ± 6 mmHg (mean ± SD) and 52 ± 6 mmHg in normocapnia (n = 23) and hypercapnia groups (n = 23), respectively. Emergence time was significantly faster in the hypercapnia group than the normocapnia group: 9.4 ± 2.4 min, hypercapnia: 5.5 ± 2.6 min, (P < 0.001) with a difference of 3.8 min on average (95% CI: 2.4 to 5.3). Spontaneous breathing established before recovery of consciousness was more evident in hypercapnia patients (normocapnia: 13%, hypercapnia: 96%, P < 0.001). Hypercapnia patients had more episodes of bradypnoea and apnoea before emergence of consciousness. In contrast, after tracheal extubation, incidences of bradypnoea and hypopnoea were more common in the normocapnia group. Undesirable cardiovascular events were not common, and no group differences were observed during emergence and postextubation periods. CONCLUSION: Hypoventilation-induced hypercapnia before desflurane cessation shortens the emergence time without causing additional clinically significant undesirable events. TRIAL REGISTRATION: UMIN Clinical Trials Registry (UMIN000020143) https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&recptno=R000023266&language=E.

BACKGROUND: Severe hypotension immediately after induction of general anesthesia (post-induction hypotension) is a common complication and is associated with a poor postoperative outcome. We hypothesized that post-induction hypotension results from cardiac dysfunction which can be assessed by preoperative echocardiography. METHODS: We retrospectively enrolled 200 patients who had undergone elective surgery within 6 months after preoperative transthoracic echocardiography. The incidence of post-induction hypotension identified from anesthesia records was defined as a decrease in mean blood pressure to ≤50 mmHg after injection of induction anesthetics prior to surgery. Logistic regression analysis of patient characteristics and echocardiographic variables was used to identify the independent factors for post-induction hypotension. RESULTS: Post-induction hypotension was found in 63 of the 200 cases (incidence 32%). Independent risk factors for post-induction hypotension were the presence of a regional wall motion abnormality (RWMA) [odds ratio (OR), 6.65.; 95% confidence interval (CI), 1.76 - 25.10], an elevated E/e' (OR, 1.13; 95% CI, 1.00 - 1.28), female gender (OR, 3.61; 95% CI, 1.37 - 9.56), and the use of an angiotensin II receptor blocker (OR, 3.17; 95% CI, 1.12 - 8.96). CONCLUSIONS: Assessment of RWMA and E/e' with preoperative transthoracic echocardiography might be helpful for stratification of patients at a risk of post-induction hypotension in general anesthesia.

BACKGROUND: The lower oesophageal sphincter (LOS) barrier serves to prevent regurgitation of gastric contents. Although general anaesthesia depresses its function, its recovery process during emergence from anaesthesia has not been systematically examined. OBJECTIVE: To explore whether recovery of lower oesophageal barrier function differed between patients receiving a mixture of 1 mg atropine and 2 mg neostigmine and those receiving 2 mg kg-1 sugammadex during emergence from anaesthesia. DESIGN: An unblinded randomised controlled pilot study. SETTING: A single university hospital from January 2016 to December 2018. PATIENTS: A total of 20 non-obese adult females undergoing minor surgery. INTERVENTION: The patients were randomly assigned to a group either receiving atropine and neostigmine or sugammadex for reversal of rocuronium. MAIN OUTCOME MEASURES: Through use of the high-resolution manometry technique, the lower oesophageal barrier pressure (PBAR: primary variable) defined as a pressure difference between pressures at the LOS and the stomach was measured at five distinguishable time points during emergence from total intravenous anaesthesia. A mixed effects model for repeated measures was used to test the hypothesis. RESULTS: In all patients baseline PBAR values were positive even under muscle paralysis and general anaesthesia before administration of reversal agents, and did not differ between the groups (P = 0.299). During recovery from muscle paralysis and general anaesthesia, PBAR (mean ± SD) significantly increased (P = 0.004) from 17.0 ± 2.9 to 21.0 ± 5.0 mmHg in the atropine and neostigmine group (n = 8) and from 19.1 ± 9.0 to 24.5 ± 12.7 mmHg in the sugammadex group (n = 11). PBAR significantly increased immediately after return of consciousness in both groups, whereas return of muscle tone, lightening of anaesthesia and tracheal extubation did not change it. CONCLUSION: Recovery of the lower oesophageal barrier function does not differ between patients receiving either atropine and neostigmine or sugammadex and is completed after recovery of consciousness from general anaesthesia. TRIAL REGISTRATION: UMIN Clinical Trials Registry: UMIN000020500: https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&recptno=R000023594&type=summary&language=E.

Nocturnal periodic breathing of chronic opioid users has been predominantly documented by the use of polysomnography. No previous studies have assessed the opioid effects of respiratory rhythms throughout the day without the use of physical restraint. We recently developed a contact-free unconstraint vital sign monitoring system with four load cells placed under the bed legs, which allows continuous measurements of respiratory change at the center of gravity on the bed. We aimed to reveal details of the patient's 24-h respiratory status under a monitoring system and to test the hypothesis that respiratory rhythm abnormalities are opioid dose-dependent and worsen during the night time. Continuous 48-h respiratory measurements were successfully performed in 51 patients with advanced cancer (12 opioid-free patients and 39 opioid-receiving patients). Medians of respiratory variables with minimal body movement artifacts were calculated for each 8-h split time period. Compared with opioid-free patients, opioid-receiving patients had slower respiratory rate with higher respiratory rate irregularity without changing tidal centroid shift regardless of the time period. Irregular ataxic breathing was only identified in opioid-receiving patients (33%, P = 0.023) whereas incidence rate of periodic breathing did not differ between the groups. Multivariate regression analyses revealed that opioid dose was an independent risk factor for occurrence of irregular breathing [odds ratio 1.81 (95% CI: 1.39-2.36), P < 0.001], and ataxic breathing [odds ratio 2.08 (95% CI: 1.60-2.71), P < 0.001]. Females developed the ataxic breathing at lower opioid dose compared with males. We conclude that respiratory rhythm irregularity is a predominant specific feature of opioid dose-dependent respiratory depression particularly in female patients with advanced cancer.NEW & NOTEWORTHY Through usage of a novel contact-free unconstraint vital sign monitoring system with four load cells placed under the bed legs allowing continuous measurements of respiratory changes of center of gravity on the bed, this study is the first to assess detailed respiratory characteristics throughout day and night periods without interference of daily activities in patients with advanced cancer receiving opioids. Respiratory rhythm irregularity is a predominant specific feature of opioid dose-dependent respiratory depression particularly in female patients with advanced cancer.

Background and Aim: Standardization of the sedation protocol during radiofrequency ablation (RFA) in patients with hepatocellular carcinoma (HCC) is needed. This randomized, single-blind, investigator-initiated trial compared clinical outcomes during and after RFA using propofol and midazolam, respectively, in patients with HCC. Methods: Few- and small-nodule HCC patients (≤3 nodules and ≤3 cm) were randomly assigned to either propofol or midazolam. Patient satisfaction was assessed using a 100-mm visual analog scale (VAS) (1 mm = not at all satisfied, 100 mm = completely satisfied). Sedation recovery rates 1, 2, 3, and 4 h after RFA were evaluated based on Modified Observer's Assessment of Alertness/Sedation (MOAA/S) scores; full recovery was defined as a MOAA/S score of 5. Results: Between July 2013 and September 2017, 143 patients with HCC were enrolled, and 135 patients were randomly assigned to the treatment group. Compared with midazolam, propofol exhibited similar median procedural satisfaction (propofol: 73.1 mm, midazolam: 76.9 mm, P = 0.574). Recovery rates 1 and 2 h after RFA were higher in the propofol group than in the midazolam group. Meanwhile, recovery rates observed 3 and 4 h after RFA were similar in the two groups. The safety profiles during and after RFA were almost identical in the two groups. Conclusion: Patient satisfaction was almost identical in patients receiving propofol and midazolam sedation during RFA. Propofol sedation resulted in reduced recovery time compared with midazolam sedation in patients with HCC. The safety profiles of both propofol and midazolam sedation during and after RFA were acceptable.

症例は75歳女性.14年前に末梢型慢性血栓塞栓性肺高血圧症と診断され,薬物治療抵抗性の肺高血圧が持続していた.S状結腸癌を指摘され,腹腔鏡下S状結腸切除術が予定された.術前の右心カテーテル検査で重症肺高血圧を認めたため,バルーン肺動脈形成術を施行し,肺高血圧の改善を得た後に手術を行った.術中は動脈血二酸化炭素分圧-呼気終末二酸化炭素分圧較差を循環動態の指標として麻酔管理を行い,特に合併症なく終了した.慢性血栓塞栓性肺高血圧症患者の非心臓手術は慎重な周術期管理を要する疾患ではあるが,適切な術前評価と治療介入を行うことにより,安全に手術中の全身管理を施行することが可能であった.(著者抄録)

BACKGROUND: An increasing number of patients come to the operating room in use of opioid analgesics. They have different levels of tolerance to opioid effects which challenge the anesthesiologists in search of safe and effective opioid dosing perioperatively. The tested hypothesis is that simple measures introduced will allow us to measure tolerance qualitatively. Opioid effects on pain (analgesia) and dyspnea sensations (relieving effect) are tested. Patients were allocated to three groups according to pre-operative analgesics: (1) control, without any opioid analgesics, (2) weak opioid, and (3) strong opioid. Pressure pain threshold (PPT) and no-respiratory sensation period (NRSP) were measured at two points: before and 3 min after intravenous fentanyl administration. RESULTS: A total of 58 (43 controls, 9 weak opioids, and 6 strong opioids) patients were enrolled. PPT and NRSP, after iv 2 μg/kg ideal body weight (IBW) fentanyl, were significantly elevated in the control patients (PPT: 6.2 ± 2.1 N to 9.2 ± 3.9 N, p < 0.0001, NRSP: 17.8 ± 10.8 s to 22.8 ± 18.7 s, p < 0.005, paired t test). However, preoperative opioid use, though with tendency, did not show a significant decrease of the opioid effect. Due to an insufficient number of participants, no conclusion could be drawn. Further analysis of the data from control patients showed a significant difference between the two sexes in sensitivity to PPT and NRSP, as well as fentanyl effect on PPT. CONCLUSIONS: Current data showed a simple method of measuring the opioid effect on two dimensions: pain and respiration. Though not able to show a qualitative measurement of tolerance formation in opioid-users, data from control patients showed females to be more sensitive to pain and dyspnea but is less sensitive to the opioid effect. Further studies are necessary to show whether these gender differences serve as clinical relevance. TRIAL REGISTRATION: UMIN, UMIN 000011580. Registered 27 August 2013, https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000013352&language=J.

BACKGROUND: Sedation is commonly performed for the endoscopic submucosal dissection (ESD) of early gastric cancer. Severe hypoxemia occasionally occurs due to the respiratory depression during sedation. AIM: To establish predictive models for respiratory depression during sedation for ESD. METHODS: Thirty-five adult patients undergoing sedation using propofol and pentazocine for gastric ESDs participated in this prospective observational study. Preoperatively, a portable sleep monitor and STOP questionnaires, which are the established screening tools for sleep apnea syndrome, were utilized. Respiration during sedation was assessed by a standard polysomnography technique including the pulse oximeter, nasal pressure sensor, nasal thermistor sensor, and chest and abdominal respiratory motion sensors. The apnea-hypopnea index (AHI) was obtained using a preoperative portable sleep monitor and polysomnography during ESD. A predictive model for the AHI during sedation was developed using either the preoperative AHI or STOP questionnaire score. RESULTS: All ESDs were completed successfully and without complications. Seventeen patients (49%) had a preoperative AHI greater than 5/h. The intraoperative AHI was significantly greater than the preoperative AHI (12.8 ± 7.6 events/h vs 9.35 ± 11.0 events/h, P = 0.049). Among the potential predictive variables, age, body mass index, STOP questionnaire score, and preoperative AHI were significantly correlated with AHI during sedation. Multiple linear regression analysis determined either STOP questionnaire score or preoperative AHI as independent predictors for intraoperative AHI ≥ 30/h (area under the curve [AUC]: 0.707 and 0.833, respectively) and AHI between 15 and 30/h (AUC: 0.761 and 0.778, respectively). CONCLUSION: The cost-effective STOP questionnaire shows performance for predicting abnormal breathing during sedation for ESD that was equivalent to that of preoperative portable sleep monitoring.

OBJECTIVES: Coagulation function dynamically changes during cardiac surgery and is normalized after surgery. The authors investigated changes of coagulation function during cardiac surgery and after mimicked salvaged blood transfusion (SBT), and determined background risk factors for coagulation dysfunction by thromboelastmetry including maximum clot firmness of fibrinogen assay (FIBTEM-MCF: primary variable). DESIGN: Prospective observational study with ex vivo laboratory experiment. SETTING: University hospital. PARTICIPANTS: Consecutive 65 adult elective cardiac surgery patients being scheduled to use cell salvage technique. INTERVENTIONS: Arterial blood sampling (preoperative: after anesthesia induction, and postoperative: after reversal of heparin), and ex vivo dilution of postoperative blood with salvaged blood (7.4%: 2.5 mL + 0.2 mL and 18.5%: 2.2 mL + 0.5 mL). MEASUREMENTS AND MAIN RESULTS: Thromboelastometry was performed for the preoperative blood sample, and postoperative blood samples mixed with different amount of the salvaged blood. Preoperative FIBTEM-MCF significantly decreased after cardiac surgery (16.5 [95% confidence interval (15.4-17.6)] mm to 9.5 [8.4-10.6] mm, p < 0.0001). In vitro 7.4% and 18.5% salvaged blood addition dose-dependently reduced FIBTEM-MCF (9.1 [95% confidence interval (8.0-10.1)] mm, 7.9 [6.8-9.0] mm, respectively, p < 0.0001). Preoperative FIBTEM-MCF and changes of FIBTEM-MCF during cardiac surgery were independent risk factors for development of the FIBTEM-MCF 8 mm or less after in vitro salvaged blood addition. Furthermore, residual heparin within salvaged blood was indicated by significant increase of intrinsic assay-clotting time/ heparin assay-clotting time after 18.5% in vitro salvaged blood addition (p < 0.0001). CONCLUSIONS: Salvaged blood transfusion of more than 18.5% whole blood volume may impair coagulation function particularly in patients with lower FIBTEM-MCF before and after cardiac surgery.

The purpose of this study is to compare changes in breathing patterns elicited by hypoxic stress and/or anesthetic stress in mice. Spontaneously breathing anesthetized mice whose tracheae were intubated with a tracheal cannula were challenged with hypoxic stress and/or sevoflurane-induced anesthetic stress while ventilation was measured with a pneumotachograph. When anesthesia was maintained at a light level with inhalation of 2.3 % sevoflurane (0.7 MAC), exposure to severe hypoxic gas (5% O2 in N2) triggered a breathing pattern characterized by gasping respiration. Inhalation of a high concentration of sevoflurane (6.5 %: 2.0 MAC) under hyperoxia elicited the same gasping. Also, the combination of mild hypoxia (inhalation of 10 % O2 in N2) and moderate sevoflurane anesthesia (3.25 %: 1.0 MAC) consistently elicited the same gasping, while mild hypoxic and moderate anesthetic stress alone did not elicit any gasping. These findings suggest that both hypoxia-induced gasping and sevoflurane-induced gasping could be generated by the same intrinsic mechanism within the brainstem.

AIM: We tested a hypothesis that postoperative active warming and/or arm leg stretches reduce the difference between core and skin temperatures (primary variable) improving the peripheral circulation immediately after major abdominal surgery. METHODS: Fifty-one patients undergoing major abdominal surgeries were randomly assigned to receive one of three interventions immediately after surgery; routine care (control group), mild intermittent exercise on the bed (exercise group), and forced-air warming (warming group). Core and skin temperatures and perfusion index were continuously measured from anesthesia induction to 12 h after arrival at the ward. RESULTS: Core body temperature was maintained over 37°C with a relatively greater gap between core and skin temperatures over 1°C and reduced perfusion index in the early postoperative period in the control group. In the warming group, the reduced skin temperature at arrival at the ward approximated to the core temperature leading to significant reduction of the temperature gap and increasing the perfusion index to the preoperative level. Although less evident, both the temperature gap and peripheral perfusion significantly improved in the exercise group after 6 and 8 h after arrival at the ward, respectively. CONCLUSIONS: Vasoconstriction in response to cessation after anesthesia and surgery serves to maintain core temperature, but impairs peripheral circulation. Active warming and intermittent mild exercise immediately after arrival at the ward reduces the temperature gap and improves peripheral circulation during the early postoperative period. While cost-effectiveness needs to be considered before clinical application of the intervention, the cost-free mild exercise may be a feasible option for improving postoperative patient care.

BACKGROUND: Complete removal of pain with regional anesthesia has been reported to cause fatal respiratory depression in opioid-dependent patients, which leads us to choose general anesthesia. We hereby report three cases of chronically opioid-treated cancer patients operated under spinal anesthesia without respiratory event. CASE PRESENTATION: Case 1: a 32-year-old female treated with high-dose morphine for her cancer pain was planned for cesarean section. Case 2: a 65-year-old female on moderate dose of oxycodone was planned for surgery of her femoral bone fracture. Case 3: a 65-year-old male on low-dose oxycodone was planned for intramedullary nailing for metastatic femoral bone tumor. In all three cases, spinal anesthesia was chosen. Continuous respiratory monitoring revealed no apnea or bradypnea. CONCLUSION: Spinal anesthesia was safely performed without respiratory depression in chronic opioid users for cancer pain.

Abstract: Recent evidences suggest that non-arousal mechanisms can restore and stabilize breathing in sleeping patients with obstructive sleep apnea. This possibility can be examined under deep sedation which increases the cortical arousal threshold. We examined incidences of cortical arousal at termination of apneas and hypopneas in elderly patients receiving propofol sedation which increases the cortical arousal threshold. Ten elderly patients undergoing advanced endoscopic procedures under propofol-sedation were recruited. Standard polysomnographic measurements were performed to assess nature of breathing, consciousness, and occurrence of arousal at recovery from apneas and hypopneas. A total of 245 periodic apneas and hypopneas were identified during propofol-induced sleep state. Cortical arousal only occurred in 55 apneas and hypopneas (22.5%), and apneas and hypopneas without arousal and desaturation were most commonly observed (65.7%) regardless of the types of disordered breathing. Chi-square test indicated that incidence of no cortical arousal was significantly associated with occurrence of no desaturation. Higher dose of propofol was associated with a higher apnea hypopnea index (r = 0.673, p = 0.033). In conclusion, even under deep propofol sedation, apneas and hypopneas can be terminated without cortical arousal. However, extensive suppression of the arousal threshold can lead to critical hypoxemia suggesting careful respiratory monitoring.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: Dental procedures under sedation can cause hypoxic events and even death. However, the mechanism of such hypoxic events is not well understood. WHAT THIS ARTICLE TELLS US THAT IS NEW: Apnea and hypopnea occur frequently during dental procedures under sedation. The majority of the events are not detectable with pulse oximetry. Insertion of a nasal tube with small diameter does not reduce the incidence of apnea/hypopnea. BACKGROUND: Intravenous sedation is effective in patients undergoing dental procedures, but fatal hypoxemic events have been documented. It was hypothesized that abnormal breathing events occur frequently and are underdetected by pulse oximetry during sedation for dental procedures (primary hypothesis) and that insertion of a small-diameter nasopharyngeal tube reduces the frequency of the abnormal breathing events (secondary hypothesis). METHODS: In this nonblinded randomized control study, frequency of abnormal breathing episodes per hour (abnormal breathing index) of the patients under sedation for dental procedures was determined and used as a primary outcome to test the hypotheses. Abnormal breathing indexes were measured by a portable sleep monitor. Of the 46 participants, 43 were randomly allocated to the control group (n = 23, no nasopharyngeal tube) and the nasopharyngeal tube group (n = 20). RESULTS: In the control group, nondesaturated abnormal breathing index was higher than the desaturated abnormal breathing index (35.2 [20.6, 48.0] vs. 7.2 [4.1, 18.5] h, difference: 25.1 [95% CI, 13.8 to 36.4], P < 0.001). The obstructive abnormal breathing index was greater than central abnormal breathing index (P < 0.001), and half of abnormal breathing indexes were followed by irregular breathing. Despite the obstructive nature of abnormal breathing, the nasopharyngeal tube did not significantly reduce the abnormal breathing index (48.0 [33.8, 64.4] h vs. 50.5 [36.4, 63.9] h, difference: -2.0 [95% CI, -15.2 to 11.2], P = 0.846), not supporting the secondary hypothesis. CONCLUSIONS: Patients under sedation for dental procedure frequently encounter obstructive apnea/hypopnea events. The majority of the obstructive apnea/hypopnea events were not detectable by pulse oximetry. The effectiveness of a small-diameter nasopharyngeal tube to mitigate the events is limited.

Rate of respiration is a fundamental vital sign. Accuracy and precision of respiratory rate measurements with contact-free load cell sensors under the bed legs were assessed by breath-by-breath comparison with the pneumotachography technique during two different dynamic breathing tasks in 16 awake human adults resting on the bed. The subject voluntarily increased and decreased the respiratory rate between 4 and 16 breaths/min (n = 8) and 10 and 40 breaths/min (n = 8) at every 2 breaths in 6 different lying postures such as supine, left lateral, right lateral, and 30, 45, and 60° sitting postures. Reciprocal phase changes of the upper and lower load cell signals accorded with the respiratory phases indicating respiratory-related shifts of the centroid along the long axis of the bed. Bland-Altman analyses revealed 0.66 and 1.59 breaths/min standard deviation differences between the techniques (limits of agreement: -1.22 to 1.36 and -2.96 to 3.30) and 0.07 and 0.17 breaths/min fixed bias differences (accuracy) (confidence interval: 0.04 to 0.10 and 0.12 to 0.22) for the mean respiratory rates of 10.5 ± 3.7 and 24.6 ± 8.9 breaths/min, respectively, regardless of the body postures on the bed. Proportional underestimation by this technique was evident for respiratory rates >40 breaths/min. Sample breath increase up to 10 breaths improved the precision from 1.59 to 0.26 breaths/min. Abnormally faster and slower respirations were accurately detected. We conclude that contact-free unconstraint respiratory rate measurements with load cells under the bed legs are accurate and may serve as a new clinical and investigational tool. NEW & NOTEWORTHY Four load cells placed under the bed legs successfully captured a centroid shift during respiration in human subjects lying on a bed. Breath-by-breath comparison of the breaths covering a wide respiratory rate range by pneumotachography confirmed reliability of the contact-free unconstraint respiratory rate measurements by small standard deviations and biases regardless of body postures. Abnormally faster and slower respirations were accurately detected. This technique should be an asset as a new clinical and investigational tool.

Although mice are a commonly used animal species in experimental medicine, airway management of this species is not easy due to their small size. In order to develop a new method of tracheal intubation in mice, we produced a supraglottic intubation-aid conduit (SIAC) for mice, and tested the efficacy of this device in spontaneously breathing mice anesthetized with sevoflurane inhalation. The success rate of tracheal intubation with the crude prototype of the SIAC was 50% and adverse effects on respiration and some trauma in the upper airway were occasionally observed. After refining the size and shape of the SIAC, the success rate of tracheal intubation with the refined prototype of the SIAC was 100% without any serious adverse effects. This study showed that it is possible to produce a supraglottic airway device to aid tracheal intubation in mice and that the shape and size of the SIAC play a crucial role in successful tracheal intubation in mice.

Study Objectives: Animal studies suggest a pivotal role of the hyoid bone in obstructive sleep apnea (OSA). We aimed to explore the role of the hyoid bone in humans by testing the hypotheses that muscle paralysis and lung volume (LV) changes displace the hyoid bone position particularly in people with obesity and/or OSA. Methods: Fifty patients undergoing general anesthesia participated in this study (20 participants with nonobese, non-OSA; 8 people with nonobese OSA; and 22 people with obese OSA). Three lateral neck radiographs to assess the hyoid position (primary variable) and craniofacial structures were taken during wakefulness, complete muscle paralysis under general anesthesia, and LV increase under general anesthesia. LV was increased by negative extrathoracic pressure application and LV changes were measured with a spirometer. Analysis of covariance was used to identify statistical significance. Results: Muscle paralysis under general anesthesia significantly displaced the hyoid bone posteriorly (95% CI: 1.7 to 4.6, 1.5 to 5.2, and 1.1 to 4.0 mm in nonobese non-OSA, nonobese OSA, and obese OSA groups, respectively), and this was more prominent in people with central obesity. LV increase significantly displaced the hyoid bone caudally in all groups (95% CI: 0.2 to 0.7, 0.02 to 0.6, and 0.2 to 0.6 mm/0.1 liter LV increase in nonobese non-OSA, nonobese OSA, and obese OSA groups, respectively). Waist-hip ratio was directly associated with the caudal displacement during LV increase. Conclusions: The hyoid bone plays an important role in the pathophysiology of pharyngeal airway obstruction due to muscle paralysis and LV reduction, particularly in people with obesity. Clinical Trial: UMIN Clinical Trial Registry, https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=cR000022635&language=E, UMIN000019578.

AIM: To investigate that polysomnographic monitoring can accurately evaluate respiratory disturbance incidence during sedation for gastrointestinal endoscopy compare to pulse oximetry alone. METHODS: This prospective observational study included 10 elderly patients with early gastric cancer undergoing endoscopic submucosal dissection (ESD) under propofol sedation. Apart from routine cardiorespiratory monitoring, polysomnography measurements were acquired. The primary hypothesis was tested by comparing the apnea hypopnea index (AHI), defined as the number of apnea and hypopnea instances per hour during sedation, with and without hypoxemia; hypoxemia was defined as the reduction in oxygen saturation by ≥ 3% from baseline. RESULTS: Polysomnography (PSG) detected 207 respiratory disturbances in the 10 patients. PSG yielded a significantly greater AHI (10.44 ± 5.68/h) compared with pulse oximetry (1.54 ± 1.81/h, P < 0.001), thus supporting our hypothesis. Obstructive AHI (9.26 ± 5.44/h) was significantly greater than central AHI (1.19 ± 0.90/h, P < 0.001). Compared with pulse oximetry, PSG detected the 25 instances of respiratory disturbances with hypoxemia 107.4 s earlier on average. CONCLUSION: Compared with pulse oximetry, PSG can better detect respiratory irregularities and thus provide superior AHI values, leading to avoidance of fatal respiratory complications during ESD under propofol-induced sedation.

WHAT WE ALREADY KNOW ABOUT THIS TOPIC: WHAT THIS ARTICLE TELLS US THAT IS NEW: BACKGROUND:: Complete recovery from rocuronium-induced muscle paralysis with sugammadex is reported to be delayed in elderly patients. The authors tested a hypothesis that recovery from deep neuromuscular block with low-dose sugammadex is slower (primary hypothesis) and incidence of recurarization is higher (secondary hypothesis) in elderly patients than in nonelderly patients. METHODS: In anesthetized elderly (n = 20; 76.9 ± 5.0 yr of age) and nonelderly patients (n = 20; 53.7 ± 12.8 yr of age) under deep paralysis with rocuronium, change of train-of-four ratio per minute (primary outcome variable) was measured with an acceleromyograph neuromuscular monitor during spontaneous recovery from rocuronium-induced muscle paralysis (0.6 mg/kg) and after infusion of low-dose sugammadex (50 µg · kg · min). Recurarization was defined as the negative change of train-of-four ratio. RESULTS: Spontaneous train-of-four ratio recovery rate was significantly slower in the elderly group (median [25th percentile, 75th percentile]: 1.89 [1.22, 2.90] %/min) than in the nonelderly group (3.45 [1.96, 4.25] %/min, P = 0.024). Train-of-four ratio change rate in response to low-dose sugammadex was significantly slower in elderly (0.55 [-0.29, 1.54] %/min) than in the nonelderly group (1.68 [0.73, 3.13] %/min, P = 0.024). Incidence of recurarization was significantly higher in the elderly group than in the nonelderly group (35% vs. 5%, P = 0.044). Multiple linear regression analyses indicate that slower spontaneous train-of-four ratio recovery rate and impaired renal function are two major contributing factors that decrease train-of-four ratio change rate in response to low-dose sugammadex. CONCLUSIONS: Elderly patients are at greater risk for recurarization and residual muscle paralysis when low-dose sugammadex is administered.

閉塞性睡眠時無呼吸症候群(Obstructive sleep apnea syndrome、以下OSAS)に対する口腔内装置(Oral appliance、以下OA)治療は、下顎を前方移動することで咽頭気道を開通させる。したがって咽頭気道幅径が大きいほうがOAの治療効果も高いと考えられる。咽頭気道はその周囲にある軟組織と骨組織によって規定されるので、歯列弓幅径の計測が咽頭気幅径の評価に効果的であると考え、歯列弓の長径および幅径とOA治療効果が関係しているかを後ろ向きに検討した。昭和大学藤が丘病院麻酔科口腔内装置外来を受診しOA治療を行った294名のうち、歯列模型を含め本研究の資料が揃った63名を対象とした。OA装着下の無呼吸低呼吸指数(AHI)が治療前と比べ50%以上改善し、かつ5回/時間未満となったものをResponder群とした。OA治療の効果予測因子を明らかにするため、評価項目の諸量を共変量として二項ロジスティック回帰分析を行ったところ、治療前AHI(回/時間)(オッズ比0.938、95%信頼区間0.883〜0.996)と下顎両側第一大臼歯近心頬側咬頭頂間距離(mm)(オッズ比1.146、95%信頼区間1.014〜1.295)が有意な独立影響因子として抽出された。Youden indexよりそれぞれの因子のカットオフ値は28.3回/時間(曲線下面積0.676、感度0.870、特異度0.425)、39mm(曲線下面積0.692、感度0.652、特異度0.750)であった。このことから咽頭気道幅径が大きいほうが治療効果も高いことが示唆された。(著者抄録)

閉塞性睡眠時無呼吸症候群(Obstructive sleep apnea syndrome、以下OSAS)に対する口腔内装置(Oral appliance、以下OA)治療は、下顎を前方移動することで咽頭気道を開通させる。したがって咽頭気道幅径が大きいほうがOAの治療効果も高いと考えられる。咽頭気道はその周囲にある軟組織と骨組織によって規定されるので、歯列弓幅径の計測が咽頭気幅径の評価に効果的であると考え、歯列弓の長径および幅径とOA治療効果が関係しているかを後ろ向きに検討した。昭和大学藤が丘病院麻酔科口腔内装置外来を受診しOA治療を行った294名のうち、歯列模型を含め本研究の資料が揃った63名を対象とした。OA装着下の無呼吸低呼吸指数(AHI)が治療前と比べ50%以上改善し、かつ5回/時間未満となったものをResponder群とした。OA治療の効果予測因子を明らかにするため、評価項目の諸量を共変量として二項ロジスティック回帰分析を行ったところ、治療前AHI(回/時間)(オッズ比0.938、95%信頼区間0.883〜0.996)と下顎両側第一大臼歯近心頬側咬頭頂間距離(mm)(オッズ比1.146、95%信頼区間1.014〜1.295)が有意な独立影響因子として抽出された。Youden indexよりそれぞれの因子のカットオフ値は28.3回/時間(曲線下面積0.676、感度0.870、特異度0.425)、39mm(曲線下面積0.692、感度0.652、特異度0.750)であった。このことから咽頭気道幅径が大きいほうが治療効果も高いことが示唆された。(著者抄録)

Respiratory management during general anesthesia aims to safely secure the airway and maintain adequate ventilation to deliver oxygen to the vital organs, maintaining homeostasis even during surgery. Despite its clinical importance, anesthesiologists often encounter difficulties in properly managing respiration during the perioperative period, leading to severe respiratory complications. In this year's JA symposium, 5 editorial board members of Journal of Anesthesia (JA) who are experts in the field of respiratory management in anesthesia discussed the following topics: quitting smoking before surgery: exposure to passive smoke is damaging to children, ventilator-associated pneumonia, high inspiratory oxygen concentration and lung injury, aspiration pneumonia, and postoperative respiratory management strategy in patients with obstructive sleep apnea. We hope that this special article regarding this year's JA symposium may be useful for JA readers to manage clinical anesthesia on a daily basis.

BACKGROUND: Difficult mask ventilation is common and is known to be associated with sleep-disordered breathing (SDB). It is our hypothesis that the incidence of expiratory retropalatal (RP) airway closure (primary outcome) during nasal positive pressure ventilation (PPV) is more frequent in patients with SDB (apnea hypopnea index ≥5 h-1) than non-SDB subjects. METHODS: The severity of SDB was assessed before surgery using a portable sleep monitor. In anaesthetized and paralysed patients with (n=11) and without SDB (n=9), we observed the behaviour of the RP airway endoscopically during nasal PPV with the mouth closed and determined the dynamic RP closing pressure, which was defined as the highest airway pressure above which the RP airway closure was reversed. The static RP closing pressure was obtained during cessation of mechanical ventilation in patients with dynamic RP closure during nasal PPV. RESULTS: The expiratory RP airway closure accompanied by expiratory flow limitation occurred more frequently in SDB patients (9/11, 82%) than in non-SDB subjects (2/9, 22%; exact logistic regression analysis: P=0.022, odds ratio 3.6, 95% confidence interval 1.1-15.4). Receiver operating characteristic curve analyses indicated AHI >10h-1 and presence of habitual snoring as clinically useful predictors for the occurrence of RP closure during PPV. Dynamic RP closing pressure was greater than the static RP closing pressure by approximately 4-5 cm H2O. CONCLUSIONS: Valve-like dynamic RP closure that limits expiratory flow during nasal PPV occurs more frequently in SDB patients.

BACKGROUND: Depending on upper airway patency during anesthesia induction, tidal volume achieved by mask ventilation may vary. In 80 adult patients undergoing general anesthesia, the authors tested a hypothesis that tidal volume during mask ventilation is smaller in patients with sleep-disordered breathing priorly defined as apnea hypopnea index greater than 5 per hour. METHODS: One-hand mask ventilation with a constant ventilator setting (pressure-controlled ventilation) was started 20 s after injection of rocuronium and maintained for 1 min during anesthesia induction. Mask ventilation efficiency was assessed by the breath number needed to initially exceed 5 ml/kg ideal body weight of expiratory tidal volume (primary outcome) and tidal volumes (secondary outcomes) during initial 15 breaths (UMIN000012494). RESULTS: Tidal volume progressively increased by more than 70% in 1 min and did not differ between sleep-disordered breathing (n = 42) and non-sleep-disordered breathing (n = 38) patients. In post hoc subgroup analyses, the primary outcome breath number (mean [95% CI], 5.7 [4.1 to 7.3] vs. 1.7 [0.2 to 3.2] breath; P = 0.001) and mean tidal volume (6.5 [4.6 to 8.3] vs. 9.6 [7.7 to 11.4] ml/kg ideal body weight; P = 0.032) were significantly smaller in 20 sleep-disordered breathing patients with higher apnea hypopnea index (median [25th to 75th percentile]: 21.7 [17.6 to 31] per hour) than in 20 non-sleep disordered breathing subjects with lower apnea hypopnea index (1.0 [0.3 to 1.5] per hour). Obesity and occurrence of expiratory flow limitation during one-hand mask ventilation independently explained the reduction of efficiency of mask ventilation, while the use of two hands effectively normalized inefficient mask ventilation during one-hand mask ventilation. CONCLUSIONS: One-hand mask ventilation is difficult in patients with obesity and severe sleep-disordered breathing particularly when expiratory flow limitation occurs during mask ventilation.

BACKGROUND: Water-filled laparoendoscopic surgery (WaFLES) has been proposed as a novel surgical system achieving a wide surgical field in the intra- and extraperitoneal space with continuous irrigation of isotonic fluid into the field. Despite its technical feasibility and advantages, the safety of the technique, particularly with respect to physiological functions, has not been evaluated. METHODS: Various types of minor abdominal surgeries were performed under general anesthesia in nine adult pigs either by conventional laparoscopy (n = 3) or WaFLES (n = 6). In addition to esophageal temperature and body weight, cardiorespiratory variables such as blood pressure, heart rate, and arterial blood gas parameters were compared before and after the surgeries. Blood samples were obtained for assessing changes in biochemical parameters before and after the surgeries. RESULTS: Three to seven hours of various surgeries were completed without critical cardiorespiratory events in all animals. Oxygenation and ventilation were maintained regardless of the techniques used for the surgeries. A minor increase of body weight (2.5% of initial body weight), metabolic acidosis, hyperkalemia, and impaired hepatic function were observed after WaFLES surgeries. CONCLUSIONS: The preliminary study indicated no serious immediate adverse effects of the WaFLES technique.

BACKGROUND: Laparoscopic and robot-assisted surgeries are performed under carbon dioxide insufflation. Switching from gas to an isotonic irrigant introduces several benefits and avoids some adverse effects of gas insufflation. We developed an irrigating device and apparatus designed for single-incision laparoscopic surgery and tested its advantages and drawbacks during surgery in a porcine model. MATERIALS AND METHODS: Six pigs underwent surgical procedures under general anesthesia. A 30-cm extracorporeal cistern was placed over a 5-6-cm abdominal incision. The abdomen was irrigated with warm saline that was drained via a suction tube placed near the surgical field and continuously recirculated through a closed circuit equipped with a hemodialyzer as a filter. Irrigant samples from two pigs were cultured to check for bacterial and fungal contamination. Body weight was measured before and after surgery in four pigs that had not received treatments affecting hemodynamics or causing diuresis. RESULTS: One-way flow of irrigant ensured laparoscopic vision by rinsing blood from the surgical field. Through a retroperitoneal approach, cystoprostatectomy was successfully performed in three pigs, nephrectomy in two, renal excision in two, and partial nephrectomy in one, under simultaneous ultrasonographic monitoring. Through a transperitoneal approach, liver excision and hemostasis with a bipolar sealing device were performed in three pigs, and bladder pedicle excision was performed in one pig. Bacterial and fungal contamination of the irrigant was observed on the draining side of the circuit, but the filter captured the contaminants. Body weight increased by a median of 2.1% (range, 1.2-4.4%) of initial weight after 3-5 hours of irrigation. CONCLUSIONS: Surgery under irrigation is feasible and practical when performed via a cistern through a small abdominal incision. This method is advantageous, especially in the enabling of continuous and free-angle ultrasound observation of parenchymal organs. Adverse effects of abdominal irrigation need further assessment before use in humans.

© 2015 American Brachytherapy Society. Background and Purpose: To relieve the pain and distress experienced by women who undergo high-dose-rate intracavitary radiotherapy (HDR-ICRT) for cervical cancer and to improve the current status of gynecologic brachytherapy in Japan, a new intravenous anesthetic protocol involving the administration of a combination of propofol and ketamine was developed. The primary aim of this study is to investigate the efficacy and safety of this new anesthetic protocol during HDR-ICRT for cervical cancer. Methods and Materials: All the patients who were diagnosed with cervical cancer between December 2008 and February 2011, treated with three-channel brachytherapy and subjected to the new sedation protocol, were evaluated. A visual analog scale (VAS) was used to assess the pain during brachytherapy, and we collected VAS score at the next HDR-ICRT. Toxicities were graded using the Common Toxicity Criteria, version 3. Results: A total of 178 sessions of HDR-ICRT were delivered to 57 patients. The patients' median VAS pain score was 0 (range, 0-10). The most frequent side effect was Grade 1-2 nausea, which occurred in 33 sessions (34%). However, 13 of 14 patients received concurrent cisplatin chemotherapy. None of the patients experienced Grade 3 or 4 adverse events. Conclusions: We have demonstrated that our new intravenous anesthetic protocol produces appropriate effects and can be performed by radiation oncologists who were required to finish training in basic life support and the cooperative system of emergency according to in-house guideline.

The pharyngeal airway is surrounded by soft tissues that are also enclosed by bony structures such as the mandible, maxilla, and cervical spine. The passive pharyngeal airway is therefore structurally analogous to a collapsible tube within a rigid box. Cross-sectional area of the tube is determined by transmural pressure, the pressure difference between intraluminal and extraluminal pressures. Due to a lack of knowledge on the influence of extraluminal soft tissue pressure on the human pharyngeal airway patency, we hypothesized that application of negative external pressure to the submental region decreases collapsibility of the passive pharynx, and that obese individuals have less response to the intervention than nonobese individuals. Static mechanical properties of the passive pharynx were compared before and during application of submental negative pressure in 10 obese and 10 nonobese adult women under general anesthesia and paralysis. Negative pressure was applied through use of a silicone collar covering the entire submental region and a vacuum pump. In nonobese subjects, application of submental negative pressure (-25 and -50 cmH2O) significantly decreased closing pressures at the retropalatal airway by 2.3 ± 3.2 cmH2O and 2.0 ± 3.0 cmH2O, respectively, and at the retroglossal airway by 2.9 ± 2.7 cmH2O and 3.7 ± 2.6 cmH2O, respectively, and the intervention stiffened the retroglossal pharyngeal airway wall. No significant mechanical changes were observed during application of submental negative pressure in obese subjects. Conclusively, application of submental negative pressure was found to decreases collapsibility of the passive pharyngeal airway in nonobese Japanese women.