The saccadic reaction times to the double-step stimuli were studied in three human subjects to ascertain the saccadic visual tracking characteristics. Responses to simple step and double-step target motions were measured where the target mode and stimulus durations were randomized. To measure the eye movement the Photo-electric Eye Monitor was constructed based on limbus tracking. The results indicate that observers represented two kind of responses (A-or B-type) depending upon the stimulus duration. The percentage of occurrances increased as the stimulus duration increased from 50 to 200 msec. When the subject responded to both target motions, the reaction time of the second saccade was shorter than that of the first. The successive visual information is to change continuously the reaction time or cancel the initial saccade. Our results revealed that parallel data processing characteristics of the visual tracking systems and the saccadic decision-makings are influenced by the temporal relationships.
Adult ; Eye Movements* ; Human ; Male ; Motion Perception* ; Reaction Time* ; Saccades* ; Visual Perception*

OBJECTIVES: The percentage of positional sleep apnea in obstructive sleep apnea (OSA) varies in different reports from 9% to 60%. If there is a positional dependency in patients with OSA, positional therapy alone could be successful in treating about 50% of all OSA cases. The aim of this report is to compare anthropomorphic and polysomnographic data between the positional sleep apnea group and non-positional sleep apnea group with OSA whose conditions were diagnosed in our sleep clinic. METHODS: This is a retrospective study of anthropomorphic and polysomnographic data of patients with OSA who was performed a nocturnal polysomnography. Positional sleep apnea was defined as having a supine apnea-hypopnea index (AHI) of twice or more compared to the AHI in the non-supine position. The patients were divided in the positional sleep apnea group and the non-positional sleep apnea group. RESULTS: In 101 patients with OSA, 81 were male, and the mean age was 49.2+/-11.9 years. Seventy-six (75.2%) were diagnosed as the positional sleep apnea. Waist to hip ratio and body mass index (BMI) were significantly higher in non-positional sleep apnea group. The frequency of severe OSA was significantly higher in this group. In the positional sleep apnea group, nocturnal sleep quality was better preserved, and consequently these patients were less sleepy during daytime. AHI was significantly lower and minimal arterial oxygen saturation during sleep was significantly higher in this group. CONCLUSION: The percentage of positional sleep apnea in OSA was 75.2%. AHI, BMI, and waist to hip ratio were lower in the positional sleep apnea group. These patients have less severe breathing abnormalities than the non-positional sleep apnea group in polysomnography.
Body Mass Index ; Dependency (Psychology) ; Humans ; Male ; Oxygen ; Polysomnography ; Respiration ; Retrospective Studies ; Sleep Apnea Syndromes ; Sleep Apnea, Obstructive ; Waist-Hip Ratio

OBJECTIVES: Several studies suggest that nocturia may be related to obstructive sleep apnea syndrome (OSAS). The mechanism by which OSAS develops nocturia has not been determined. The present study aimed to determine the prevalence of nocturia among adults with OSAS and to identify factors that may be predictive in this regard. METHODS: Retrospective review of clinical and polysomnographic data obtained from patients evaluated at the sleep clinics of the St. Paul's Hospital between 2009 and 2012. The urinary symptoms were assessed on the basis of the International Prostate Symptom Score (IPSS). Pathologic nocturia was defined as two or more urination events per night. OSAS was defined as apnea-hypopnea index (AHI) > or =5. A multivariate analysis using logistic regression was performed to examine the relationship between polysomnographic variables and the presence of pathologic nocturia, while controlling for confounding factor. RESULTS: A total of 161 men >18 years of age (mean age 46.7+/-14.1), who had been referred to a sleep laboratory, were included in the present study. Among these, 27 patients with primary snoring and 134 patients with obstructive sleep apnea were confirmed by polysomnography. Nocturia was found in 53 patients with OSAS (39.6%) and 8 patients with primary snoring (29.6%). The AHI was higher in patients with nocturia than in those without nocturia (p=0.001). OSAS patients with nocturia had higher arousal index (p=0.044), and lower nadir oxyhemoglobin saturation (p=0.001). Multiple regression analysis showed that age (beta=0.227, p=0.003), and AHI (beta=0.258, p=0.001) were associated with nocturia, and that the presence of pathologic nocturia was predicted by age (OR 1.04 ; p=0.004) and AHI (OR 1.02 ; p=0.001). CONCLUSION: Nocturia is common among patients with OSAS. The strongest predictors of nocturia are age and AHI in patients with OSAS.
Adult ; Arousal ; Humans ; Logistic Models ; Male ; Multivariate Analysis ; Nocturia* ; Oxyhemoglobins ; Polysomnography ; Prevalence* ; Prostate ; Retrospective Studies ; Sleep Apnea, Obstructive* ; Snoring ; Urination

A new method is described which uses photo-electric matrix method to measure two-dimensional eye movements. This system is composed of the detector unit (monitor), matrix and correction circuits and stimulus generator. A light and small detector unit attached to the modified trial frame transduces positional informations and can be achieved head-mounting. The instrument operates in the infrared, so that it does not interfere with normal vision, and over a two-dimensional visual field to +/-15 degrees. A system for generating a fixed target whose velocity, displacement, form, intensity, and other characteristics can be varied systematically also is described. The operating procedures are described and operating records are shown. Electrical and optical modifications of the present system will make possibIe the measurement of more smaller movement of the eye. Extensions and improvement of the technique of measurement are discussed briefly.
Eye Movements* ; Visual Fields

OBJECTIVES: The Berlin Questionnaire (BQ) has been used to help identify patients at high risk of having sleep apnea in primary care. But it has not been validated in a sleep clinic for Korean patients. The aim of this study is to evaluate the usefulness of the BQ as a screening tool for obstructive sleep apnea (OSA) for Korean patients in a sleep clinic. METHODS: The BQ was prospectively applied to 121 subjects with OSA suspicion who visited to our sleep clinic. All subjects performed overnight polysomnography. OSA was defined as an apnea-hypopnea index (AHI) > or =5. We investigated the sensitivity, specificity, positive and negative predictive values of the BQ according to severity by AHI. RESULTS: In 121 subjects, 73.6% were males, with a mean age of 48.8+/-13.0 years. Twenty-five (20.6%) patients did not have OSA (AHI<5), 30 (25%) patients had mild OSA (AHI> or =5 and <15), 26 (21.4%) had moderate (AHI> or =15 and <30), and 40 (33%) had severe OSA (AHI> or =30). The BQ identified 69.4% of the patients as being at high risk for having OSA. The sensitivity and specificity of the BQ were 71.9% and 40%, for AHI> or =5, 75.8% and 38.2% for AHI> or =15, 77.5% and 34.6% for AHI> or =30, respectively. The positive and negative predictive values of the BQ were 82.1% and 27.0% for AHI> or =5, respectively. Positive and negative likelihood ratios were 1.2 and 0.7, and the overall diagnostic accuracy of the BQ was 65.3%, using an AHI cut-off of 5. CONCLUSION: Due to modest sensitivity and low specificity, the BQ does not seem to be an appropriate tool for identifying patients with obstructive sleep apnea in a sleep clinic population.
Berlin ; Humans ; Male ; Mass Screening ; Polysomnography ; Primary Health Care ; Prospective Studies ; Surveys and Questionnaires ; Sensitivity and Specificity ; Sleep Apnea Syndromes ; Sleep Apnea, Obstructive

We studied the association of nonspecific bronchial hyperresponsiveness with general characteristics, exposure concentration, respiratory symptoms, chest x-ray findings, past histories and pulmonary function. We determined bronchial hyperresponsiveness by methacholine challenge test. And we conducted a respiratory symptom questionnaire and performed spirometry on 111 workers occupationally exposed to isocyanates in various industries. About 21.6% of subjects had bronchial hyperresponsiveness. No significant differences were observed between the hyperresponsive and non-responsive group with respect to age, sex, employment period, height, and smoking histories cough and breathlessness were significantly associated with the bronchial hyperresponsiveness. The hyperresponsive group had more experience of bronchitis and asthma in the past than the non-responsive group. The lower FEV1 and FEV1 % were closely related with bronchial hyperresponsiveness. Bronchial hyperrespoosiveness seems to be associated with some of respiratory symptoms, past histories and pulmonary function parameters in workers exposed to isocyanates.
Asthma ; Bronchitis ; Cough ; Employment ; Isocyanates* ; Methacholine Chloride ; Occupations ; Surveys and Questionnaires ; Smoke ; Smoking ; Spirometry ; Thorax

BACKGROUND: Aging is a significant issue worldwide, and Korea is one of the most rapidly aging countries. Along with the demographic transition, the age structure of intensive care unit (ICU) patients changes as well. METHODS: The aim of this study was to analyze the change in age distribution of the ICU patients over the last 10 years and its effect on clinical outcomes. Single-center, retrospective analysis of all patients aged ≥18 years admitted to either the medical or surgical ICU at St. Paul's Hospital, The Catholic University of Korea, between January 2005 and December 2014 was conducted. For clinical outcome, in-hospital mortality, duration of ICU stay, and hospital stay were analyzed. Cost analysis was performed to show the economic burden of each age strata. RESULTS: A total of 10,366 ICU patients were admitted to the chosen ICUs during the study period. The proportion of elderly patients aged ≥65 years increased from 47.9% in 2005 to 63.7% in 2014, and the proportion of the very elderly patients aged ≥80 years increased from 12.8% to 20.7%. However, this increased proportion of elderly patients did not lead to increased in-hospital mortality. The percent of ICU treatment days attributable to elderly patients increased from 51.1% in year 2005 to 64.0% in 2014. The elderly ICU patients were associated with higher in-hospital mortality compared to younger age groups. CONCLUSIONS: The proportion of elderly patients admitted to ICUs increased over the last decade. However, overall in-hospital mortality has not increased during the same period.
Age Distribution ; Aged* ; Aging ; Costs and Cost Analysis ; Critical Care* ; Hospital Mortality ; Humans ; Intensive Care Units* ; Korea* ; Length of Stay ; Mortality ; Population Dynamics ; Retrospective Studies*

No abstract available.
Intensive Care Units ; Sepsis ; Critical Illness ; Chronic Disease ; Hospital Mortality

This study aims to ascertain the human saccadic visual tracking characteristics by measuring the eye movement to the double-step stimuli. Responses to simple step and double-step target motions were measured where the target mode and stimulus durations were randomized. To measure the eye movement the Photo-electric Eye Monitor was constructed based on limbus tracking. The results indicate that observers represented two kind of responses (A-or B-type) depending upon the stimulus duration. The percentage of occurrances increased as the stimulus duration increased from 50 to 200 msec. When the subject responded to both target motions, the reaction time of the second saccade was shorter than that of the first. The successive visual information is to change continuously the reaction time or cancel the initial saccade. Our results revealed that parallel data processing characteristics of the visual tracking systems and the saccadic decision-makings are influenced by the temporal relationships.
Eye Movements ; Humans* ; Reaction Time ; Saccades

The purpose of this review is to examine the ways in which eye position and eye movements are measured in order to justify the choice of method for the study concerning the eye movement control systems. The oculomotor control systems were reviewed previously as a viewpoint of measuring objects. Because of the different aspects of eye movement which have been considered, various techniques have been developed-each having its own characteristics of range, sensitivity, bandwidth, stability and ease of application. This study is directed at discussing the pros and cons inherent in a basic method of measurement and to indicate the interesting historical development of oculography as new technologies were employed. Various methods are summarized and photo-electronic method(Limbus tracking technique) was chosen which is most available for the future experimentation.
Eye Movements*