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Automated detection of anesthetic depth levels using chaotic features with artificial neural networks

Lalitha V, Eswaran C

J Med Syst, 2007 Dec;31(6):445-52.
PMID: 18041276

Monitoring the depth of anesthesia (DOA) during surgery is very important in order to avoid patients' interoperative awareness. Since the traditional methods of assessing DOA which involve monitoring the heart rate, pupil size, sweating etc, may vary from patient to patient depending on the type of surgery and the type of drug administered, modern methods based on electroencephalogram (EEG) are preferred. EEG being a nonlinear signal, it is appropriate to use nonlinear chaotic parameters to identify the anesthetic depth levels. This paper discusses an automated detection method of anesthetic depth levels based on EEG recordings using non-linear chaotic features and neural network classifiers. Three nonlinear parameters, namely, correlation dimension (CD), Lyapunov exponent (LE) and Hurst exponent (HE) are used as features and two neural network models, namely, multi-layer perceptron network (feed forward model) and Elman network (feedback model) are used for classification. The neural network models are trained and tested with single and multiple features derived from chaotic parameters and the performances are evaluated in terms of sensitivity, specificity and overall accuracy. It is found from the experimental results that the Lyapunov exponent feature with Elman network yields an overall accuracy of 99% in detecting the anesthetic depth levels.

Matched MeSH terms: Monitoring, Intraoperative/methods*
ONSD monitoring under anesthesia for middle ear surgery

Suresh V, Magoon R

J Anesth, 2024 Aug;38(4):565-566.
PMID: 37889341 DOI: 10.1007/s00540-023-03274-5
Matched MeSH terms: Monitoring, Intraoperative/methods
Fulltext End-tidal to arterial carbon dioxide partial pressure difference during craniotomy in anaesthetised patients

Husaini J, Choy YC

Med J Malaysia, 2008 Dec;63(5):384-7.
PMID: 19803296 MyJurnal

This study to evaluate the relationship between end-tidal carbon dioxide pressure (ETCO2) and arterial partial pressure of carbon dioxide (PaCO2) included 35 patients between the ages of 18 and 65 years, ASA grade 1 and 2, who had elective craniotomies. Measurements of PaCO2 and ETCO2 were taken simultaneously: 1) 10 minutes after induction of general anaesthesia, 2) after cranium opening prior to dural incision, 3) start of dural closure. There was significant correlation between ETCO2 and PaCO2 (correlation coefficient: 0.571, 0.559 and 0.629 respectively). The mean (SD) difference for PaCO2 and ETCO2 were: 3.84 (2.13), 4.85 (5.78) and 3.91 (2.33) mmHg respectively. Although there was agreement, the bias is of significant clinical importance. In conclusion, we find that ETCO2 consistently underestimated the value of PaCO2 during craniotomy.

Matched MeSH terms: Monitoring, Intraoperative/methods*
Intraoperative echocardiographic delineation of the high take-off coronary ostia during an extensive surgical repair of the bicuspid aortic valve and dilated sinotubular junction: a case report

Jung HJ, Kwon WK, Lee SJ, Mohamed N, Shin BM, Lee J, et al.

BMC Anesthesiol, 2016 10 04;16(1):83.
PMID: 27716083

BACKGROUND: This study reports the efficacy of intraoperative transesophageal echocardiography (TEE) for evaluation of high take-off coronary ostia and proximal coronary arterial flows as an alternative to preoperative coronary angiography.
CASE PRESENTATION: In a 65-year old male undergoing the bicuspid aortic valve (BAV) repair and the extensive remodeling of dilated sinus and tubular junction, and preoperative coronary angiography were unsuccessfully completed due to an allergic reaction to the contrast medium. Intraoperative TEE by employing various 3-dimensional volume images of coronary ostia and Doppler tracings of the coronary arterial flows enabled a thorough pre-procedural evaluation of the high take-off coronary arteries and post-procedural evaluation by confirming the absence of any compromise in coronary arterial flow.
CONCLUSION: In the present case, intraoperative application of various TEE imaging modalities enabled comprehensive evaluation of high-taking off coronary artery, as an alternative to preoperative coronary angiography, in a patient undergoing an extensive aortic valve and aortic root repair procedure.

Matched MeSH terms: Monitoring, Intraoperative/methods
Significant factors influencing inadvertent hypothermia in pediatric anesthesia

Lai LL, See MH, Rampal S, Ng KS, Chan L

J Clin Monit Comput, 2019 Dec;33(6):1105-1112.
PMID: 30915603 DOI: 10.1007/s10877-019-00259-2

Thermal imbalances are very common during surgery. Hypothermia exposes the patient to post-operative shivering, cardiac dysfunction, coagulopathy, bleeding, wound infection, delayed anesthesia recovery, prolonged hospital stay and increased hospitalization cost. There are many factors contributing to intraoperative hypothermia. This is a prospective cohort study conducted through observation and measurement of pediatric surgical patients' temperature. Convenience sampling methods were used in this study. Initial skin temperature and core temperature at 10 min, 30 min,1 h, 2 h, 3 h, 4 h, 5 h, 6 h and at the end of surgery were recorded. Body temperature was monitored from time of transfer to the operating table until recovery and discharge to the respective pediatric ward. The overall incidence of intraoperative hypothermia was still very high at about 46.6% even though active and passive temperature management were carried out during surgery. Patient's age, body weight, duration of surgery, type of surgery, intraoperative blood loss, type of anesthesia and operating room temperature were factors that contributed to intraoperative hypothermia. Hypothermia is common in surgery, especially in major and long duration surgery. Intraoperative hypothermia can be life threatening if it is not handled carefully. Various methods are used before, during and after surgery to maintain a patient's body temperature within the normothermia range. The use of an active warming device like the Bair Hugger® air-forced warming system seems to be a good method for reducing the risk of intraoperative hypothermia and effectively maintaining body temperature for all major and minor surgeries.

Matched MeSH terms: Monitoring, Intraoperative/methods