Machine Learning Model for Anesthetic Risk Stratification for Gynecologic and Obstetric Patients: A Novel Approach for Early Detection.

BACKGROUND: Preoperative evaluation is important, our study explored the application of machine learning methods for anesthetic risk classification and for the evaluation of the contributions of various factors. To minimize the effects of confounding variables during model training, we used a homogenous group with similar physiological states and ages undergoing similar pelvic organ-related procedures not involving malignancies. OBJECTIVE: Data on women of reproductive age (age = 20-50 years) who underwent gestational or gynecological surgery between January 1, 2017, and December 31, 2021, were obtained from the National Taiwan University Hospital Integrated Medical Database. METHODS: We first performed an exploratory analysis and selected key features. We then performed data preprocessing to acquire relevant features related to preoperative examination. To further enhance predictive performance, we employed the log likelihood ratio algorithm to generate comorbidity patterns. Lastly, we input the processed features into the light gradient boosting machine (LightGBM) model for training and subsequent prediction. RESULTS: A total of 10,892 patients were included. Within this data set, 9893 patients were classified as having low anesthetic risk (American Society of Anesthesiologists physical status score 1-2), and 999 patients were classified as having high anesthetic risk (American Society of Anesthesiologists physical status score > 2). The area under the receiver operating characteristic curve of the LightGBM model was 90.25. CONCLUSIONS: By combining comorbidity information and clinical laboratory data, our methodology based on the LightGBM model provides more accurate predictions for anesthetic risk classification. CLINICALTRIAL: This study was registered with the Research Ethics Committee of the National Taiwan University Hospital with trial number 202204010RINB.

Feasibility of Nonintubated Anesthesia for Lumboperitoneal Shunt Implantation.

Lumboperitoneal shunt (LPS) implantation is a cerebrospinal fluid diversion therapy for the communicating type of normal-pressure hydrocephalus (NPH); NPH mainly affects older adults. However, endotracheal intubation for mechanical ventilation with muscle relaxant increases perioperative and postoperative risks for this population. Based on knowledge from nonintubated thoracoscopic surgery, which has been widely performed in recent years, we describe a novel application of nonintubated anesthesia for LPS implantation in five patients. Anesthesia without muscle relaxants, with a laryngeal mask in one patient and a high-flow nasal cannula in four patients, was used to maintain spontaneous breathing during the surgery. The mean anesthesia time was 103.8 min, and the mean operative duration was 55.8 min. All patients recovered from anesthesia uneventfully. In our experience, nonintubated LPS surgery appears to be a promising and safe surgical technique for appropriately selected patients with NPH.

Deceleration capacity of heart rate variability as a predictor of sedation related hypotension.

High risk and geriatric patients are supposed to suffer higher risks of hypotension underwent painless endoscopic procedures. This study evaluated different biomarkers associated with hypotension in off-site patients and aimed to determine the most relevant risk factors in space and monitoring limited environment. The inclusions of this observational cohort study underwent complex endoscopic procedures were sedated with age-adjusted doses of target-controlled infusion of propofol. The following pre-sedative parameters were analysed: time domain, frequency domain, and Deceleration capacity (DC) of heart rate variability, estimated cardiac output data and the index of cardiac contractility from the cardiometer. Patients were divided into hypotension group (blood pressure < 90 mmHg or a > 35% decrease) and non-hypotension group according to peri-sedative blood pressure, regression analysis is used to examine the association between factors and hypotension. Total data from 178 patients (age range: 33-94 years) were analysed. Age was not significantly different between the hypotension and non-hypotension groups (p = 0.978). Among all the factors, DC was most associated with hypotension (p = 0.05), better than cardiometer, age, and ASA status. In conclusion, DC, which can be interpreted as the indicator of parasympathetic activity and was significantly and negatively correlated with sedation-related hypotension. Pre-sedative measuring DC from routine ECG monitoring is simple and cost-effective and should be added to haemodynamic monitoring in the endoscopic room.

Multi-timescale phase-amplitude couplings in transitions of anesthetic-induced unconsciousness.

Under general anesthesia (GA), advanced analysis methods enhance the awareness of the electroencephalography (EEG) signature of transitions from consciousness to unconsciousness. For nonlinear and nonstationary signals, empirical mode decomposition (EMD) works as a dyadic filter bank to reserve local dynamical properties in decomposed components. Moreover, cross-frequency phase-amplitude coupling analysis illustrates that the coupling between the phase of low-frequency components and the amplitude of high-frequency components is correlated with the brain functions of sensory detection, working memory, consciousness, and attentional selection. To improve the functions of phase-amplitude coupling analysis, we utilized a multi-timescale approach based on EMD to assess changes in brain functions in anesthetic-induced unconsciousness using a measure of phase-amplitude coupling. Two groups of patients received two different anesthetic recipes (with or without ketamine) during the induction period of GA. Long-term (low-frequency) coupling represented a common transitional process of brain functions from consciousness to unconsciousness with a decay trend in both groups. By contrast, short-term coupling reflected a reverse trend to long-term coupling. However, the measures of short-term coupling also reflected a higher degree of coupling for the group with ketamine compared with that without ketamine. In addition, the coupling phase is a factor of interest. The phases for different combinations of coupling components showed significant changes in anesthetic-induced unconsciousness. The coupling between the delta-band phase and the theta-band amplitude changed from in-phase to out-phase coupling during the induction process from consciousness to unconsciousness. The changes in the coupling phase in EEG signals were abrupt and sensitive in anesthetic-induced unconsciousness.

I-Gel is a suitable alternative to endotracheal tubes in the laparoscopic pneumoperitoneum and trendelenburg position.

BACKGROUND: The use of supraglottic airway devices (SADs) in surgeries with laparoscopic pneumoperitoneum and Trendelenburg (LPT) positioning is controversial due to concerns about insufficient pulmonary ventilation and aspiration. In this prospective, randomized-controlled trial, we evaluated whether the i-gel, a new second generation SAD, provides an effective alternative to an endotracheal tube (ETT) by comparing respiratory parameters and perioperative respiratory complications in non-obese patients. METHODS: In a randomized controlled trial, forty anesthetized patients with ASA I-II were divided into equally sized i-gel and ETT groups. We evaluated the respiratory parameters in the supine and LPT position in comparison between the two groups. The leak fraction was our primary outcome, which was defined as the leak volume divided by the inspired tidal volume. The leak volume was the difference between the inspired and expired tidal volumes. We also monitored pulmonary aspiration and respiratory complications during the perioperative period. RESULTS: In the LPT position, there were no differences in the leak fraction (median [IQR]) between the i-gel and ETT groups (6.20[3.49] vs 6.38[3.71] %, P = 0.883). In the i-gel group, notably less leakage was observed in the LPT position than in the supine position (median [IQR]: 7.01[3.73] %). This phenomenon was not observed in the ETT group. The rate of postoperative sore throat was also significantly lower in the i-gel group than in the ETT group (3/17 vs 9/11). No vomitus nor any signs associated with aspiration were noted in our patients after extubation in the follow-up prior to discharge. CONCLUSIONS: The i-gel provides a suitable alternative to an ETT for surgeries with LPT positioning in non-obese patients. TRIAL REGISTRATION: Registered at Clinicaltrials.gov NCT02462915 , registered on 1 June 2015.

Investigating Power Density and the Degree of Nonlinearity in Intrinsic Components of Anesthesia EEG by the Hilbert-Huang Transform: An Example Using Ketamine and Alfentanil.

Empirical mode decomposition (EMD) is an adaptive filter bank for processing nonlinear and non-stationary signals, such as electroencephalographic (EEG) signals. EMD works well to decompose a time series into a set of intrinsic mode functions with specific frequency bands. An IMF therefore represents an intrinsic component on its correspondingly intrinsic frequency band. The word of 'intrinsic' means the frequency is totally adaptive to the nature of a signal. In this study, power density and nonlinearity are two critical parameters for characterizing the amplitude and frequency modulations in IMFs. In this study, a nonlinearity level is quantified using degree of waveform distortion (DWD), which represents the characteristic of waveform distortion as an assessment of the intra-wave modulation of an IMF. In the application of anesthesia EEG analysis, the assessments of power density and DWD for a set of IMFs represent dynamic responses in EEG caused by two different anesthesia agents, Ketamine and Alfentanil, on different frequency bands. Ketamine causes the increase of power density and the decrease of nonlinearity on γ-band neuronal oscillation, which cannot be found EEG responses of group B using Alfentanil. Both agents cause an increase of power density and a decrease of nonlinearity on ß-band neuronal oscillation accompany with a loss of consciousness. Moreover, anesthesia agents cause the decreases of power density and nonlinearity (i.e. DWD) for the low-frequency IMFs.

Sample entropy analysis of EEG signals via artificial neural networks to model patients' consciousness level based on anesthesiologists experience.

Electroencephalogram (EEG) signals, as it can express the human brain's activities and reflect awareness, have been widely used in many research and medical equipment to build a noninvasive monitoring index to the depth of anesthesia (DOA). Bispectral (BIS) index monitor is one of the famous and important indicators for anesthesiologists primarily using EEG signals when assessing the DOA. In this study, an attempt is made to build a new indicator using EEG signals to provide a more valuable reference to the DOA for clinical researchers. The EEG signals are collected from patients under anesthetic surgery which are filtered using multivariate empirical mode decomposition (MEMD) method and analyzed using sample entropy (SampEn) analysis. The calculated signals from SampEn are utilized to train an artificial neural network (ANN) model through using expert assessment of consciousness level (EACL) which is assessed by experienced anesthesiologists as the target to train, validate, and test the ANN. The results that are achieved using the proposed system are compared to BIS index. The proposed system results show that it is not only having similar characteristic to BIS index but also more close to experienced anesthesiologists which illustrates the consciousness level and reflects the DOA successfully.

Unidirectional cross-activation of GRPR by MOR1D uncouples itch and analgesia induced by opioids.

Spinal opioid-induced itch, a prevalent side effect of pain management, has been proposed to result from pain inhibition. We now report that the µ-opioid receptor (MOR) isoform MOR1D is essential for morphine-induced scratching (MIS), whereas the isoform MOR1 is required only for morphine-induced analgesia (MIA). MOR1D heterodimerizes with gastrin-releasing peptide receptor (GRPR) in the spinal cord, relaying itch information. We show that morphine triggers internalization of both GRPR and MOR1D, whereas GRP specifically triggers GRPR internalization and morphine-independent scratching. Providing potential insight into opioid-induced itch prevention, we demonstrate that molecular and pharmacologic inhibition of PLCß3 and IP3R3, downstream effectors of GRPR, specifically block MIS but not MIA. In addition, blocking MOR1D-GRPR association attenuates MIS but not MIA. Together, these data suggest that opioid-induced itch is an active process concomitant with but independent of opioid analgesia, occurring via the unidirectional cross-activation of GRPR signaling by MOR1D heterodimerization.

Coronary artery dissection in a patient with traumatic femoral shaft fracture.

We report a 24-year-old man who developed postoperative pulmonary edema and desaturation, after open reduction with internal fixation for left femoral shaft fracture sustained in a motorcycle accident. Cardiac catheterization revealed a left anterior descending coronary artery dissection. Review of his present history, showed that he neither had chest discomfort nor suffered from hemodynamic decompensation preoperatively. Only the abnormal 12-lead ECG with moderate tachycardia was suggestive of myocardial ischemia. Coronary artery dissection, although uncommon, is a disastrous complication following blunt chest trauma, and needs thorough preoperative evaluation to exclude its occurrence.

Optimizing epidural fentanyl loading dose for early labor pain.

OBJECTIVE: Sufficient sensory blockade between L1 and T10 is required to relieve visceral pain during early labor. We examined whether the addition of fentanyl to a loading dose of 0.0625% bupivacaine could provide dose-dependent analgesic effects on early-stage labor pain. METHODS: Sixty parturients who requested epidural analgesia for labor pain were enrolled and randomly allocated to one of three groups. Group A (n = 20) received 10 mL of 0.0625% epidural bupivacaine as a loading dose alone. Group B (n = 20) received the same bupivacaine loading dose in combination with 2 microg/mL fentanyl. Group C (n = 20) received the same loading bupivacaine dose plus 4 microg/mL fentanyl. All patients received diluted bupivacaine plus 2 microg/mL fentanyl at a rate of 10 mL/hr as a maintenance dose. Fifteen minutes later, we recorded the highest cephalic and lowest caudal anesthetized dermatomes, side effects, and the number of patients who asked for supplemental analgesia. RESULTS: The highest anesthetized cephalic dermatome was at the level of T12 (T9-L1) in Group A, T9 (T8-T12) in Group B and T7 (T5-T9) in Group C (p < 0.05 among the three groups). Eleven patients (55%) requested supplemental bupivacaine for inadequate analgesia in Group A, six in Group B (30%), and none in Group C (0%). Pruritus was reported by seven (35%) patients in Group B and eight (40%) patients in Group C, but none in Group A. CONCLUSION: The addition of fentanyl to epidural bupivacaine dose-dependently increased the analgesic effect and higher loading doses of fentanyl increased the dermatomic coverage. We suggest that 0.0625% bupivacaine plus 4 microg/mL fentanyl is the ideal loading dose to provide the greatest segmental analgesia for early labor pain with minimal side effects.

Alteration of capnogram as the first sign of pneumothorax in an infant who underwent bronchoscopy with jet ventilation.

A 3-month-old male infant underwent rigid bronchoscopy with manual jet ventilation due to persistent right upper lobe collapse under capnographic surveillance. The CO2 waveform abruptly vanished soon after application of jet ventilation, while breath sounds decreased gradually until the left side breath sounds were barely audible. Progressive abdominal distension with protruding umbilicus was also detected at the same time. Under the impression of bilateral tension pneumothorax, emergent needle decompression was carried out. In this case, the sudden onset of CO2 waveform change was the first warning sign of pneumothorax, which is the most common complication of jet ventilation. Therefore, we strongly recommend that continuous capnographic surveillance be applied during bronchoscopy with jet ventilation.