What are standard monitoring devices for anesthesia in future?

Monitoring the patient's physiological functions is critical in clinical anesthesia. The latest version of the Japanese Society of Anesthesiologists' Guidelines for Safe Anesthesia Monitoring, revised in 2019, covers various factors, including electroencephalogram monitoring, oxygenation, ventilation, circulation, and muscle relaxation. However, with recent advances in monitoring technologies, the information provided has become more detailed, requiring practitioners to update their knowledge. At a symposium organized by the Journal of Anesthesia in 2023, experts across five fields discussed their respective topics: anesthesiologists need to interpret not only the values displayed on processed electroencephalogram monitors but also raw electroencephalogram data in the foreseeable future. In addition to the traditional concern of preventing hypoxemia, monitoring for potential hyperoxemia and the effects of mechanical ventilation itself will become increasingly important. The importance of using AI analytics to predict hypotension, assess nociception, and evaluate microcirculation may increase. With the recent increase in the availability of neuromuscular monitoring devices in Japan, it is important for anesthesiologists to become thoroughly familiar with the features of each device to ensure its effective use. There is a growing desire to develop and introduce a well-organized, integrated "single screen" monitor.

Perioperative loss of the psoas major muscle area index in elderly patients with hip fracture: spinal anesthesia versus general anesthesia-a retrospective cohort study.

PURPOSE: In hip fracture patients aged ≥ 80 years, we investigated whether the perioperative reduction in the psoas major muscle index (PMI) for spinal anesthesia was less than that for general anesthesia. METHODS: A total of 262 patients surgically treated for intertrochanteric or femoral neck fractures between August 2015 and August 2022 were enrolled. After adjusting for propensity score matching, 50 patients were included in this analysis. After matching, patients were divided into those receiving spinal or general anesthesia. We measured the psoas major muscle area (PMA) by adjusting for the patient's height as PMA (cm2) divided by height (m) squared. The adjusted PMA was defined as the PMI. We calculated the variability in PMI (ΔPMI) before and after surgery. The primary outcome was the proportion of patients with a > 10% reduction in ΔPMI. The secondary outcomes were the mean ΔPMI and estimated factors affecting the postoperative reduction in the PMI. We compared the primary and secondary outcomes between spinal and general anesthesia. RESULTS: The proportion with a > 10% reduction in ΔPMI did not differ between spinal and general anesthesia (36.0% vs. 40.0%, odds ratio:1.19, 95% CI:0.38-3.72, p = 0.31). The ΔPMI did not differ between spinal and general anesthesia (- 8.7% ± 7.9% vs. - 8.9% ± 8.3%, p = 0.93). The factors affecting the postoperative reduction in the PMI were male sex, preoperative non-sarcopenia, and intramedullary nailing. CONCLUSION: There was no significant difference in ΔPMI between hip fracture patients ≥ 80 years of age receiving spinal versus general anesthesia undergoing surgical treatment.

Total intravenous anesthesia management with simultaneous use of remimazolam and propofol: A case series of three patients.

Remimazolam is an ultra-short-acting benzodiazepine anesthetic agent. Because of pharmacodynamic interactions in the sedation effect between benzodiazepines and propofol, the combination of remimazolam and propofol may allow for a dose reduction of each agent while providing effective sedation for general anesthesia. We experienced three cases in which general anesthesia was induced with remimazolam and maintained with relatively small doses of remimazolam and propofol target-controlled infusion. In all cases, electroencephalogram changes associated with sedation induced by remimazolam were carefully observed during anesthesia induction before administration of propofol. The time required for recovery from anesthesia was 8-13 min. This is the first report in which remimazolam and propofol were concomitantly used for general anesthesia based on the concept of pharmacodynamic interaction. This anesthetic combination may be beneficial in reducing doses of each anesthetic and avoiding delayed recovery from anesthesia, although further study is needed to confirm this.

Use of intraoperative transesophageal echocardiography and epiaortic ultrasound to diagnose false lumen enlargement of chronic aortic dissection.

In communicating aortic dissection, if only the entry or reentry is closed, residual blood flow may cause enlargement of the false lumen. In this case, surgeons were unable to occlude the entry with a stent graft due to the strong flexion of the bilateral common iliac arteries, so they closed only the reentry in the hope that blood flow from the reentry would be high. Unfortunately, due to the high blood flow from the entry, the false lumen was enlarged. But the use of transesophageal echocardiography and epiaortic ultrasound contributed to its diagnosis.

How obesity affects the disposition of intravenous anesthetics.

PURPOSE OF REVIEW: Understanding the changes in drug disposition of intravenous anesthetics in patients with obesity and administering appropriate doses are critical to avoid intraoperative awareness with recall because of underdosing and over-sedation and delayed emergence due to overdosing. Pharmacokinetic simulation or target-controlled infusion (TCI) using models that have been adapted to patients with obesity are necessary to select appropriate dosing regimens. This review aimed to describe the pharmacokinetic concepts underpinning the use of intravenous anesthetics, including propofol, remifentanil, and remimazolam, in patients with obesity. RECENT FINDINGS: In the last 5 years, a series of pharmacokinetic models for propofol, remifentanil, and remimazolam that were estimated from populations that included obese patients have been published. These new pharmacokinetic models can be considered 'second generation' compared with earlier models in that they expand the range of covariate effects (e.g. the extremes of body weight and age) accounted for by the models. The predictive performances of each pharmacokinetic model have been shown in the literature to be within clinically acceptable limits. Among them, the propofol model by Eleveld et al. has been externally validated and has shown reasonable predictive accuracy. SUMMARY: Pharmacokinetic simulations or TCI using pharmacokinetic models that account for the influence of obesity on a drug's disposition are essential to predict plasma/effect-site concentrations of intravenous anesthetics and understand the temporal profile of drug concentrations and effect in patients with obesity, particularly severe obesity.

Analgesia nociception index and high frequency variability index: promising indicators of relative parasympathetic tone.

At present, there is no objective and absolute measure of nociception, although various monitoring techniques have been developed. One such technique is the Analgesia Nociception Index (ANI), which is calculated from heart rate variability that reflects the relative parasympathetic tone. ANI is expressed on a non-unit scale of 0-100 (100 indicates maximal relative parasympathetic tone). Several studies indicated that ANI-guided anesthesia may help reduce intraoperative opioid use. The usefulness of ANI in the intensive care unit (ICU) and during surgery has also been reported. However, some limitations of ANI have also been reported; for example, ANI is affected by emotions and some drugs. In 2022, a high frequency variability index (HFVI), which was renamed from ANI and uses the same algorithm as ANI, was commercialized; therefore, ANI/HFVI are currently in the spotlight. Unlike ANI, HFVI can be displayed along with other biometric information on the Root® monitor. ANI/HFVI monitoring may affect the prognosis of not only patients in the perioperative period but those in ICU, those who receive home medical care, or outpatients. In this article, we present an updated review on ANI that has been published in the last decade, introduce HFVI, and discuss the outlooks of ANI/HFVI.

The effects of chest drainage on pressure-controlled ventilation.

BACKGROUND: The use of pressure-controlled ventilation (PCV) for anesthesia management is becoming more commonly used. Chest drainage is commonly performed after thoracic surgery, and the negative pressure it generates might affect the transpulmonary pressure (TPP). In the present study, we investigated how chest drainage could affect ventilating conditions during PCV. METHODS: We created a hand-made simple thoracic and lung model, which was connected to an anesthesia machine. The tidal volume (TV) was measured with positive end-expiratory pressure (PEEP) 0 and no chest drainage (baseline), followed by 10 cmH2O PEEP/no drainage, 10 cmH2O PEEP/drainage with - 10 cmH2O and 10 cmH2O PEEP/drainage with - 20 cmH2O. Finally, TV with 20 cmH2O and 30 cmH2O PEEP/no drainage was measured. Driving (inspiratory) pressure was maintained at 20 cmH2O during the whole experiment. RESULTS: TV was significantly increased by applying 10 cmH2O PEEP compared with baseline, further increased by applying - 10 cmH2O by drainage, similar to the value with PEEP 20 cmH2O with no drainage (end-tidal TPP of 20 cmH2O for both). TV decreased to < 50% of the baseline by applying 10 cmH2O PEEP with - 20 cmH2O by drainage, which was similar to that with 30 cmH2O PEEP with no drainage (end-tidal TPP of 30 cmH2O for both). CONCLUSIONS: TV was maintained at similar levels with the same TPP, regardless of PEEP or negative pressure by chest drainage change, suggesting that negative intrapleural pressure by the chest tube drainage system might mimic PEEP from the point of TV.

Anterior knee pain post-multiple surgeries for tibia fracture effectively managed with infrapatellar fat pad injection: a case report.

BACKGROUND: The anterior knee compartment is filled by the infrapatellar fat pad (IFP) and has been emphasized as a source of anterior knee pain (AKP). CASE PRESENTATION: A 51-year-old woman sustained a right tibial plateau and open diaphyseal fracture 2 years earlier. She remained with chronic AKP after undergoing bone fixations. Increased anterior portion of the IFP brightness and decreased adipose tissue gliding with flexion and extension compared to the unaffected side was shown on ultrasonography. An injection of 0.2% lidocaine between the patellar tendon and IFP, and into the IFP under ultrasound guidance, immediately relieved the pain. The pain kept recurring although injections were effective for a while; thus, surgery was scheduled. Scar tissue on the IFP surface was endoscopically excised and her pain dramatically reduced. CONCLUSION: This is the first report in which the detection of increased brightness on ultrasound of IFP and the injections into the IFP triggered an additional surgical intervention. Ultrasound evaluation and injection may be beneficial in pain clinic patients presenting with AKP and may provide an opportunity for diagnosis.

A case requiring re-thoracotomy due to a significant reduction of tidal volume after commencement of chest tube drainage under pressure control ventilation following lower lobectomy.

BACKGROUND: The use of pressure-controlled ventilation (PCV) during one lung ventilation (OLV) has been popular to avoid high airway pressure. We experienced a case of a significant reduction of tidal volume (TV) after commencement of chest tube drainage under PCV following lower lobectomy, which required re-thoracotomy to evaluate the degree of air leak. CASE PRESENTATION: A 70-year-old man was scheduled for a lower lobectomy. OLV was managed by PCV. The driving pressure was set at 15-20 cmH2O with 4 cmH2O of positive end-expiratory pressure (PEEP). A chest drainage tube was placed after completion of lobectomy. To switch OLV to two lung ventilation (TLV), PCV settings were changed to the driving pressure at 10 cmH2O with 4 cmH2O of PEEP, which generated 450 ml of TV. Immediately after applying drainage (-10 cmH2O), TV decreased down to 250 ml. To maintain 450 ml of TV, PCV was switched to volume-controlled ventilation with 450 ml of TV, which raised the plateau pressure close to 24 cmH2O. Re-thoracotomy was done; however, significant findings were not detected. CONCLUSIONS: We experienced a case of a significant reduction of TV immediately after chest tube drainage following lower lobectomy. Probably, negative intrapleural pressure increased the residual volume, which might have significantly affected the limited lung volume after lobectomy, resulting in decreasing TV during PCV.

Respiration and circulation affected by gas leakage into the abdominal cavity during endoscopic esophageal submucosal dissection after gastrostomy: a case report.

BACKGROUND: Pneumoperitoneum is a common complication of percutaneous endoscopic gastrostomy (PEG). We report a case of circulatory and respiratory depression due to pneumoperitoneum caused by PEG dislodgement during endoscopic submucosal dissection (ESD) surgery. CASE PRESENTATION: A 46-year-old man with PEG for dysphagia underwent ESD for esophageal cancer under general anesthesia. The patient developed a gradual increase in peak inspiratory pressure, followed by a decrease in peripheral oxygen saturation (SpO2) and blood pressure, as well as an increase in heart rate (HR) during endoscopic submucosal ESD for esophageal cancer. We suspected mediastinal emphysema due to esophageal perforation, but the surgery was successfully completed. Postoperative computed tomography (CT) revealed that the abdominal and gastric walls, which had been fixed by PEG, were detached, resulting in a large amount of intra-abdominal gas and mediastinal emphysema. CONCLUSIONS: ESD in patients with PEG should be performed carefully because of the possibility of intraoperative PEG dislodgement and pneumoperitoneum caused by insufflation gas leakage.

Evaluation of microbial contamination on cuff syringe, cuff pressure gauge, and their surroundings in the operating room.

BACKGROUND: Some institutions reuse cuff syringes and do not periodically sterilize cuff pressure gauges. Pathogenic bacterial contamination of such equipment may increase the probability of pathogen transmission to patients during anesthetic procedures. Therefore, microbial contamination on cuff syringes, cuff pressure gauges, and their surroundings was assessed in the operating rooms of a university-affiliated tertiary care hospital in Japan. METHODS: This study was conducted between April and May 2019 in 14 operating suites at a hospital. The following sites in each operating suite were sampled: cuff syringe (inner/outer components), outer components of cuff pressure gauge, cuff syringe and cuff pressure gauge storage drawers, and computer mice. The swabs were directly streaked onto agar plates and incubated. Then, the bacterial species were identified using mass spectrometry. RESULTS: The highest bacterial isolation was observed in computer mice, followed by the outside of cuff pressure gauges and the drawers of cuff pressure gauges (92.9, 78.6, and 64.3%, respectively). Most of the identified bacteria belonged to the Bacillus species, with colonization rates of 85.7, 57.1, and 57.1% on computer mice, cuff pressure gauges, and cuff pressure gauge storage drawers, respectively. Coagulase-negative Staphylococcus was found in 35.7% of the specimens and was more prevalent on computer mice (71.4%), followed by on cuff pressure gauges (64.3%). CONCLUSION: Anesthesiologists should be aware of the possible pathogen contamination risk from cuff syringes, cuff pressure gauges, or associated equipment and take appropriate infection control measures to minimize the risk of pathogenic transmission.

The use of the Sanuki airway™ in three patients with suspected difficult airway.

The Sanuki airway is a single-use intubation oral airway designed for fiberoptic bronchoscope intubation. Sanuki airway has a bite block function and a wide lumen for the tracheal tube to pass through. Here, three cases are reported in which Sanuki airway was used for oral fiberoptic bronchoscope intubation. Case 1 is a patient who presented with reduced mouth opening and intraoral edema due to facial bone fracture. Case 2 is a patient who suffered from severe neck stiffness and had reduced mouth opening due to systemic psoriatic arthritis. Case 3 is a patient who suffered from multiple facial traumas and was in a full-stomach state. In all patients, advancing the tip of the bronchofiber into the larynx using Sanuki airway was possible under dexmedetomidine sedation, which contributed to the successful tracheal intubation. Using Sanuki airway may be considered an option for oral fiberoptic bronchoscope intubation in patients anticipated with difficult airways.

Update on the SedLine® algorithm for calculating the Patient State Index of older individuals during general anesthesia: a randomized controlled trial.

BACKGROUND: The SedLine® sensor processes (Masimo Corporation; Irvine, CA, USA) raw electroencephalogram (EEG) signals and displays the depth of sedation as a Patient State Index (PSi). Reliance on standard processed EEG data and failure to recognize age-related effects can lead to an erroneous interpretation that low-amplitude EEG findings in an older patient signify an insufficient depth of anesthesia presented as abnormally high PSi values (AHPSi). We hypothesized that the incidence of AHPSi would decrease with the use of the recently-updated version of the SedLine® sensor, in which the Bispectral Index (BIS) values were used to titrate anesthesia. METHODS: Thirty-three patients undergoing sevoflurane-remifentanil anesthesia were randomized into two groups. SedLine® sensors designed based on an old (v.1203) or updated (v.2000) algorithms were used. The BIS (v.4.1) and absolute index of total EEG power (TP) were simultaneously recorded. The attending anesthesiologists titrated the anesthetics, and BIS was maintained at 40-60. The incidence of AHPSi (PSi>50 with BIS 40-60) was calculated during the first 30 min after the start of surgery. RESULTS: Compared to the old algorithm group, the incidence of AHPSi was significantly lower in the updated algorithm group (26.7% vs. 4.2%, P<0.001). Lower TP values and the use of the old algorithm have significant effect on increased PSi values (P<0.001). CONCLUSIONS: The incidence of AHPSi decreased with the use of the updated version of the SedLine® algorithm.

Transient maintenance of tracheal patency upon the insertion of a flexible bronchoscope in a patient with an anterior mediastinal mass: a case report.

BACKGROUND: Patients with an anterior mediastinal mass are at risk of perioperative respiratory collapse. CASE PRESENTATION: A 74-year-old woman with a large anterior mediastinal mass that led to partial tracheal collapse (shortest diameter, 1.3 mm) was scheduled for tracheobronchial balloon dilation and stent placement under general anesthesia. Although veno-venous extracorporeal membrane oxygenation (V-V ECMO) had been established, maximum flow was limited to 1.6 L/min, and general anesthesia induction was followed by hypoxia probably due to inadequate ventilation. A flexible bronchoscope was inserted through the tracheal lumen that was being compressed by the anterior mass; this not only increased tracheal patency but also enabled positive pressure ventilation and resulted in recovery from hypoxia. Scheduled procedures were successfully performed without complications. CONCLUSION: We describe a case wherein tracheal patency was transiently maintained by inserting a flexible bronchoscope in a patient with an anterior mediastinal mass.