Osteoporosis Risk Prediction for Bone Mineral Density Assessment of Postmenopausal Women Using Machine Learning

PURPOSE: A number of clinical decision tools for osteoporosis risk assessment have been developed to select postmenopausal women for the measurement of bone mineral density. We developed and validated machine learning models with the aim of more accurately identifying the risk of osteoporosis in postmenopausal women compared to the ability of conventional clinical decision tools. MATERIALS AND METHODS: We collected medical records from Korean postmenopausal women based on the Korea National Health and Nutrition Examination Surveys. The training data set was used to construct models based on popular machine learning algorithms such as support vector machines (SVM), random forests, artificial neural networks (ANN), and logistic regression (LR) based on simple surveys. The machine learning models were compared to four conventional clinical decision tools: osteoporosis self-assessment tool (OST), osteoporosis risk assessment instrument (ORAI), simple calculated osteoporosis risk estimation (SCORE), and osteoporosis index of risk (OSIRIS). RESULTS: SVM had significantly better area under the curve (AUC) of the receiver operating characteristic than ANN, LR, OST, ORAI, SCORE, and OSIRIS for the training set. SVM predicted osteoporosis risk with an AUC of 0.827, accuracy of 76.7%, sensitivity of 77.8%, and specificity of 76.0% at total hip, femoral neck, or lumbar spine for the testing set. The significant factors selected by SVM were age, height, weight, body mass index, duration of menopause, duration of breast feeding, estrogen therapy, hyperlipidemia, hypertension, osteoarthritis, and diabetes mellitus. CONCLUSION: Considering various predictors associated with low bone density, the machine learning methods may be effective tools for identifying postmenopausal women at high risk for osteoporosis.

Development of a New Index for Mortality Prediction Due to Hemorrhagic Shock using Lactate Concentration and Perfusion in S-D Rats

PURPOSE: We proposed a new index for predicting death resulting from hemorrhagic shock, which was calculated by dividing measured lactate concentration by perfusion. METHODS: Using 24 Sprague-Dawley (S-D) rats, we induced uncontrolled hemorrhage and then measured blood lactate concentration and perfusion in addition to vital signs such as heart rate, blood pressure, respiration rate and temperature. Perfusion and lactate concentration were measured by laser Doppler flowmetry and a lactate concentration meter, respectively. We collected the data for 15 min, which consisted of 3 intervals after homeostasis, and thus obtained a new index. RESULTS: The proposed index revealed an earlier death prediction than lactate concentration alone with the same timing as perfusion. The new index showed generally better sensitivity, specificity and accuracy than lactate concentration and perfusion. Using a receiver operating characteristic curve method, the mortality prediction with the proposed index resulted in a sensitivity of 98.0%, specificity of 90.0%, and accuracy of 93.7%. The mortality prediction with the proposed index resulted in a sensitivity of 98.0%, specificity of 90.0% and accuracy of 93.7%. CONCLUSION: This index could provide physicians, in emergency situations, with early and accurate mortality predictions for cases of human hemorrhagic shock.

Development of a New Index for Mortality Prediction Due to Hemorrhagic Shock using Lactate Concentration and Perfusion in S-D Rats

PURPOSE: We proposed a new index for predicting death resulting from hemorrhagic shock, which was calculated by dividing measured lactate concentration by perfusion. METHODS: Using 24 Sprague-Dawley (S-D) rats, we induced uncontrolled hemorrhage and then measured blood lactate concentration and perfusion in addition to vital signs such as heart rate, blood pressure, respiration rate and temperature. Perfusion and lactate concentration were measured by laser Doppler flowmetry and a lactate concentration meter, respectively. We collected the data for 15 min, which consisted of 3 intervals after homeostasis, and thus obtained a new index. RESULTS: The proposed index revealed an earlier death prediction than lactate concentration alone with the same timing as perfusion. The new index showed generally better sensitivity, specificity and accuracy than lactate concentration and perfusion. Using a receiver operating characteristic curve method, the mortality prediction with the proposed index resulted in a sensitivity of 98.0%, specificity of 90.0%, and accuracy of 93.7%. The mortality prediction with the proposed index resulted in a sensitivity of 98.0%, specificity of 90.0% and accuracy of 93.7%. CONCLUSION: This index could provide physicians, in emergency situations, with early and accurate mortality predictions for cases of human hemorrhagic shock.

Effects of Posture and Acute Sleep Deprivation on Heart Rate Variability

PURPOSE: In our previous study to investigate autonomic nervous system (ANS) activity due to radio frequency (RF) radiation using heart rate variability (HRV), drowsiness was observed in approximately half of all subjects. Therefore, the usage of HRV with unwanted drowsiness could falsely indicate the effects of RF radiation by mobile phones on the ANS. The objective of this study was to determine which posture is appropriate for accurate HRV analysis for provocation study. MATERIALS AND METHODS: A total of 52 healthy subjects (25 males and 27 females) participated in this experiment. We measured the number of times a subject showed drowsiness or sleep deprivation due to awakening, and analyzed HRV six times over 30 minutes in sitting and recumbent postures, using power spectrum. RESULTS: We employed the ratio of low frequency power to high frequency power (LFP/HFP) to analyze the changes in the ANS. The number of sleep deprivation occurrences in the sitting posture was significantly less than that in the recumbent posture (p<0.01), resulting in smaller increase of LFP/HFP. Although LFP/HFP of the two postures varied with time without any provocation, it was more stable in sitting than in recumbent postures. CONCLUSION: A sitting posture is preferable to a recumbent posture for analyzing HRV, because of decreased drowsiness and sleep deprivation, thereby decreasing variation of LFP/HFP during experiment. Considering the drowsiness, it is also recommended that any experiment should be completed within 15 minutes, if possible.

A Survival Prediction Model for Rats with Hemorrhagic Shock Using an Artificial Neural Network

PURPOSE: To achieve early diagnosis of hemorrhagic shock using a survival prediction model in rats. METHODS: We measured heart rate, mean arterial pressure, respiration rate and temperature in 45 Sprague-Dawley rats, and obtained an artificial neural network model for predicting survival rates. RESULTS: Area under the receiver operating characteristic (ROC) curves was 0.992. Applying the determined optimal boundary value of 0.47, the sensitivity and specificity of survival prediction were 98.4 and 96.6%, respectively. CONCLUSION: Because this artificial neural network predicts quite accurate survival rates for rats subjected to fixed-volume hemorrhagic shock, and does so with simple measurements of systolic blood pressure (SBP), mean arterial pressure (MAP), heart rate (HR), respiration rate (RR), and temperature (TEMP), it could provide early diagnosis and effective treatment for hemorrhagic shock if this artificial neural network is applicable to humans.

Objective Evaluation of Secondary Cleft Lip Nose Deformity by Analysis of Nostril Shape

Cleft lip is one of the most common congenital deformities in craniofacial region. However, despite many reports on the outcome of various surgical techniques from individual medical centers, the evaluation of the outcome has been based on the subjective observation. Therefore, developing a new technique of objective and scientific evaluation for the nasal deformity of secondary cleft lip and nasal deformity is important to improve the management of the cleft lip patients. The authors have proposed a new scoring model to evaluate objectively the nasal deformity. The authors put 'x' axis on the nostril sill of noncleft side and 'y' axis on nasal tip at a right angle to x axis. The nostril of noncleft side was turned around the y axis to form the mirror image on the cleft side, and following four parameters were recorded: (1) angle difference between two nostril axis, (2) center of the nostril and distance between two centers, (3) the overlapped area of two nostrils and (4) the overlapped area ratio of two nostrils. The post-surgery images were evaluated by the three plastic surgeons, using the scale of 5 percentiles. The four parameters of each image were measured using a newly developed software and correlation coefficients of each parameter and the evaluation scale by the surgeons were obtained. Among the scores from scoring model, errors greater than 10 percents were found only in 2 of 14 cases (2/14=14%), but among the scores from examiners, errors of greater than 10 percents were 4 from 14 cases (4/14=29%). Based on the results, deviation among the individual examiners can be reduced using the objective evaluation program developed in this study. The correlation coefficients between the normalized overlap area (0.78) and the distance between the centers of two nostrils (-0.82) with the evaluated scale by surgeons were high. However, the relative area and the degree difference of two nostril axis were found to be not such a good parameters in the evaluation of the nasal deformity. We developed scoring model from analysis of nostril shape and neural network which is able to evaluate cleft lip nasal deformity objectively after selection of proper parameters.

Real-Time Measurement of 3-Dimensional Eye Movements by Videooculography

BACKGROUND AND OBJECTIVES:In order to analyze and understand the oculomotor system completely, it is essential to measure horizontal, vertical, and torsional eye movements. We developed a new system of 3-dimensional videooculography that can accurately estimate the pupil center and measure torsional eye movement in real time while minimizing the errors caused by upper eyelid droop, eyelashes, corneal reflection, and eye blinking. MATERIALS AND METHOD:For accurate estimation of the center and diameter of the pupil, the edges of the pupil were searched by using a sector-form window and circle fitting was performed using the least square regression. Torsional eye movement was measured using polar cross-correlation technique with modification to lessen the errors produced by the change in pupil size. Calibrations were performed and to verify the proposed system, the linearity between the measured and actual eye movements was measured. Also, the results of the proposed system were compared with those of another commercialized system. RESULTS: The linearity between the measured and actual eye movements showed errors of less than 1%. The spatial resolutions of the system for horizontal, vertical, and torsional eye movements were 0.3, 0.4, and 0.2, respectively whereas the temporal resolution was 30 frames/sec. In comparison to the commercialized system, our system showed less artifact by eye blinking when measuring vertical eye movement. CONCLUSION:We proposed an algorithm and a system for measuring horizontal, vertical, and torsional eye movements which minimized the influence of partial eyelid closure, eyelashes, corneal reflections, and change in pupil size.

Measurement of the excessive stimulus time after the sensory threshold level during electric pulp testing / 대한치과보존학회지

Use of electric pulp testing elicits painful response in vital teeth. In this study, we examined the excessive time from pain feeling to stimulation disconnection in clinical situation. D626D (Parkell Inc., USA.) scan type electric pulp tester was used in total of 23 young healthy individuals. Each of the right central incisors and first premolars were used as testing teeth. Stimulation disconnection was achieved by EMG in anterior belly of digastric muscle, finger span, and voice and the excessive stimulation time over the sensory threshold was recorded. As a result, we found that the short responses before the stimulation disconnection appeared following order; EMG, finger span, and voice. The EMG disconnection is suggested to be used to reduce the excessive stimulus time in electric pulp testing.

How Much are Anesthesiologists Exposed to Electromagnetic Fields in Operating Rooms?

Numerous electronic devices have been introduced into the operating room. Although little is known about the relationship between exposure to electromagnetic fields (EMF) and health hazards, some authors reported its association with cancer or other diseases. We measured the amount of EMF exposure that an anesthesiologist gets in the operating room. The density of the magnetic field was checked by an extremely low frequency (ELF) field strength measurement system in the 19 operating rooms of our hospital. We measured the magnetic field intensity at a distance of 30 cm, 50 cm, and at the place where the anesthesiologist usually stands from the center of the main monitor. The average exposure quantities of magnetic fields in 19 operating rooms were 2.22 +/- 1.13 mG at 30 cm, 1.29 +/- 0.84 mG at 50 cm and 1.00 +/- 0.78 mG at the anesthesiologist's standing points respectively. Because quantities over 2 or 3 mG were accepted to be high radiation levels of EMF by many reports describing the hazards of EMF, we set 2 mG to be the cutoff value. In some of the 19 operating rooms, the measured EMF density exceeded our cutoff value. Although the health hazards related to EMF exposure are still equivocal, anesthesiologists should consider making an effort to improve their environment and reduce their exposure to EMF.

Evaluation of a Bio-impedance Method for Measuring Human Arm Movement

This study proposes a new method for measuring upper limb movement using a bio-impedance technique. Bio-impedance and joint angle were simultaneously measured during the wrist and elbow movements of 12 normal subjects. The joint angles of the wrist and elbow were estimated by measuring the bio-impedances of the forearm and upper arm, respectively. Although the measured bio-impedances on upper limbs varied among individuals, changes in the bio-impedances and joint angles of the wrist and elbow during their extension and flexion were very highly correlated, having correlation coefficients of 0.96 +/- 0.04 and -0.98 +/- 0.02, respectively. The reproducibilities of wrist and elbow bio-impedance changes were 2.1 +/- 1.0% and 1.8 +/- 1.0%, respectively. Since the proposed method is not restricted by size or the duration of measurements, it is expected to be useful for the analysis of athletic movement.

Galvanic Nystagmus in Normal Person

BACKGROUND AND OBJECTIVES: Vestibulo-ocular reflex and vestibulo-spinal reflex are induced by transmatoid galvanic stimulation of vestibular system. Nystagmus and body sway are result of each reflex. Recently, videooculograph possible to record a minute ocular movement was commonly used, vestibulo-ocular reflex induced by galvanic simualtion is easily documented. The purposes of this study are to evaluate the galvanic nystagmus in nomal persons in order to better understand the physiology of the vestibular system. MATERIALS AND METHODS: Eye movement of 20 neurootologic normal subjects by both side transmstoid galvanic stimulation (40cases) were analyzing by videonystagmography. RESULT: The direction of nystagmus in fast phase was to the negative electrode. Galvanic nystagmus was occured all normal subjects when stimulus intensity was more than 2mA. There was positive correlation between slow phase velocity(SPV) and electric current but negative correlation was noted between asymmery of SPV and electric current. CONCLUSION: It is suggested that the galvanic nystagmus test could be a new diagnostic tool for evaluation of vestibular status.

Development of Fine Time Controller of a Transtracheal Jet Ventilator and Its Experimental Application / 대한마취과학회지

BACKGROUND: Transtracheal jet ventilation (TTJV) with a large-bore angiocath that is inserted through the cricothyroid membrane can provide immediate oxygenation from a high pressure-oxygen wall outlet, as well as ventilation by means of manual triggering. However, there is widespread agreement that TTJV with a high pressure oxygen system may induce numerous complications including tracheal hemorrhage/ulceration, subcutaneous/mediastinal emphysema, and barotrauma resulting in a pneumothorax. The goal of this study was to highlight the potential effectiveness of a TTJ-ventilator with an oxygen supply pressure lower than 50 psig for proper oxygenation and ventilation avoiding the possibility of complications from a high pressure oxygen supply system. METHODS: Five mongrel dogs were intubated, paralyzed with vecuronium, and mechanically ventilated with enflurane in air maintaining the PaCO2 at 35 - 40 mmHg. A 16 G IV catheter was inserted percutaneously into the trachea below the tip of the endotracheal tube. We measured the injection volumes, entrained air volumes, and peak inflation pressures according to the changes of oxygen supply pressure (10 to 50 psig) with a fixed injection time (1 second). In addition, we evaluated the oxygenation effects of TTJV at 15 breaths per minute and an I : E 1 : 3 on 20 psig of oxygen supply pressure in hypoxic dogs. RESULTS: A 16 G angiocath provided the injected volumes from 139 ml to 595 ml according to the changes of oxygen pressure from 10 to 50 psig. The entrained air volumes were 6.7 48% of total inspirated volumes. The PaO2 was elevated over 300 mmHg and the PaCO2 was reduced to 45 mmHg within 1 minute of TTJV in hypoxic dogs. CONCLUSIONS: A TTJV system equipped with a time-controller and pressure-regulator can provide enough tidal volume to maintain oxygenation, and could minimize the volu/barotrauma of a conventional TTJV.

The Development of an Inspiratory Time Adjustable Transtracheal Jet Ventilator and Evaluation in a Human Adult Trachea-Lung Model / 대한마취과학회지

BACKGROUND: Transtracheal jet ventilation (TTJV) has been used for 'Cannot Ventilate/Cannot Intubate' situation, lefe-saving situations, by simply introducing an IV catheter (angiocatheter) through the cricothyroid membrane. To decrease the occurrence of barotrauma caused by a continuous high pressure oxygen supply while applying TTJV, it would be ideal to have a TTJV system equipped with an inspiration time adjustable function which any currently commercially available TTJV does not have. METHODS: Recently, we made a prototype of an inspiration time adjustable TTJV and measured the corresponding injection volumes and peak inflation pressures according to the changes of oxygen supply pressure and inspiration time using catheters ranging from 14 to 20 G in a simulated human adult trachea-lung model. RESULTS: A 16 G angiocatheter provided 465 +/- 5 ml of injected volume with a peak inflation pressure of 25 cmH2O under a 50 psi oxygen supply at 1 second of inspiration, which would be adequate for an adult tidal volume. When a 14 G catheter was used under the same conditions as above, the injected volume was 1128 +/- 9 ml. All injected volumes were under 310 ml when 18 and 20 G angiocathers were used at variosus driving pressures (10 - 50 psi) and inspiration time (0.5, 0.75, and 1 s). CONCLUSIONS: An inspiration time adjustable TTJV can easily provide enough tidal volume to maintain oxygenation, and could be expected to prevent or reduce barotraumatic complications such as pneumothorax.

Usefulness of a developed four-channel EGG system with running spectrum analysis

Electrogastrography (EGG) is a method of measuring action potentials on the abdomen. It is noninvasive, inexpensive and easy to measure. However, the EGG signal has a very low frequency (0.05 Hz) and an extremely low amplitude (10-100 microV). Consequently, its measured waveform is difficult to analyze and it is not yet completely understood. In this study, a four-channel EGG measurement system was built to measure the action potential of the stomach. This system was compared with the commercially available one-channel Digitrapper EGG. The 3 cpm percentages were compared between the best channel of the four-channel system and channel 1, whose electrode position was similar to the commercially available one-channel system for normal subjects. The average 3 cpm percentage of the best channel and channel 1 for preprandial measurement was 89.5% and 83.2%, respectively, and this was statistically significant (p < 0.001). Also the average 3 cpm percentage of the best channel and channel 1 for postprandial measurement was 90.4% and 76.5%, respectively, and this was statistically significant (p = 0.003). From these results, it can be concluded that a multi-channel EGG system is required for better EGG measurement.

How Much are Anesthesiologists Exposed to Electromagnetic Fields in Operating Rooms? / 대한마취과학회지

BACKGROUND: So many electronic devices have been introduced in the operating room. However, little was known about the hazards of electromagnetic fields (EMF) to the human body. We have studied about how much the anesthesiologists are exposed to EMF. METHODS: In 19 operating rooms of our hospital, the intensity of magnetic fields was measured by an ELF (Extremely low frequency) field strength measurement system. The distances were 30 cm, 50 cm and the anesthesiologist's proximity to the monitoring devices. RESULTS: The average strength of 19 operating rooms were 2.22 +/- 1.13 mG at 30 cm from the monitors, 1.29 +/- 0.84 mG at 50 cm and 1.00 +/- 0.78 mG at the anesthesiologist's stand. CONCLUSIONS: We found that in some of our operating rooms the exposure to EMF was measured above Sweden's TCO limit which has been accepted as the EMF radiation rule for computer monitors. Although the hazards of EMF have not been definitely confirmed yet, the effort not to be exposed to EMF should be considered by anesthesiologists.

A quantitative evaluation of pigmented skin lesions using the L*a*b* color coordinates

The evaluation of pigmentary skin lesions by clinical doctors has been based on subjective and qualitative judgements. Observations have mostly relied on visual inspection, making the effects of treatment difficult to evaluate with any precision. For this reason there is a real need for an objective method to evaluate prognosis after treatment. Recent scientific measurements such as reflectance spectrophotometry and reflectance colorimetry have provided accurate quantitative color information about skin lesions, but these techniques are costly and difficult to apply in the clinical field. The purpose of this study was to develop a simple and cost-effective way of evaluating treatment results. We have developed a software program using the L*a*b* color coordinate system to quantify the effect of treatment and have successfully demonstrated its clinical usefulness. Our method compares the relative color difference between normal skin and skin lesions before and after treatment, instead of measuring the absolute color of skin lesions. The accuracy of our quantitative color analysis was confirmed by the simulated images of hemangioma and ota nevus. Clinical efficacy was also confirmed through a blind test involving 3 clinicians who were asked to grade the treatment effects of 13 cases of hemangioma and 7 cases of ota nevus. These subjective clinical grades correlated well with the treatment results obtained using the proposed color analysis system (Correlation coefficient = 0.84).

Electric and laser energy for endoscopic surg

Improvements in surgery have focused on refinements in the ability to dissect and limit blood loss. The electrosurgery unit (ESU) and laser (light amplification by stimulated emission of radiation) have been widely used in recent endoscopic surgery. ESU is a form of surgery in which high-frequency (100 kHz-5 MHz) electric currents are used to incise, destroy, and remove tissue and to seal blood vessels in order to maintain hemostasis. The use of lasers in surgery has added a new dimension to operative technique through increased precision, improved hemostasis, and less tissue manipulation. This paper aims to explain the basic principles and applications of electrosurgery and lasers.

Measurement of digital blood flow using impedance plethysmography

No abstract available.

Effects of radial artery cannulation on the index finger blood flowby impedence plethysmograph / 대한구급학회지

No abstract available.

Changes of cardiac output during treadmill exercise by impedance cardiography

Nine athletes and ten nonathletes were selected randomly to study the changes of cardiac function during exercise by impedance cardiography. The speed of the treadmill was maintained at 3.4 mph, and its grade was increased by 1% (Balke protocol). The exercise was continued until the target heart rate (THR), 85% of maximum oxygen uptake (VO2max). The measured parameters for pre- and post-exercise were stroke volume (SV), heart rate (HR), and cardiac output (CO). Average stroke volume of athletes at pre-exercise, 71.1 ml, was higher than that of nonathletes, 64.6 ml, and stroke volume of the former at post-exercise, 97.0 ml, was also higher than that of the latter, 85.2 ml. Therefore, despite the lower heart rate, cardiac outputs of athletes at pre- and post-exercise, 4.98 and 16.3 L/min, were higher than those of nonathletes, 4.87 and 14.2 L/min. For the second phase of the study, cardiac outputs of three subjects were measured during the continuous treadmill exercise with newly developed electrodes and shoes for minimizing motion artifact. Though there were several studies measuring cardiac output during continuous bicycle exercise, this is thought to be the first study in the world measuring cardiac output during continuous treadmill exercise without aid of ensemble averaging.