PURPOSE: Negative studies provide valuable information. However, conducting studies with inadequate power is unethical and an inefficient use of resources. Moreover, inaccurate interpretations from underpowered studies result in false conclusions that alter clinical interventions and deter further research. The purpose of this study was to determine the prevalence of negative studies with inadequate power in the Journal of the Korean Society of Emergency Medicine (JKEM). METHODS: We assessed all papers in JKEM from 2009 to 2012. We sought published evidence that a post-hoc power analysis had been performed in association with the main hypothesis of the paper. All clinical research studies containing the phrase "no difference" were identified. Data necessary for power calculation were extracted from applicable studies. RESULTS: There were a total of 351 papers in which a statistical comparison was undertaken. Out of 351 original articles, 170(48.4%) were negative studies that contained enough information for analysis. Out of 126 negative studies in JKEM, only 21((16.7%) had performed a power analysis demonstrating adequate sample size. In addition, only 6.3% of dichotomous variable articles and 10.3% of continuous variable articles had adequate power. Levels of adeadequate power in negative studies did not improve over time (p=0.148). CONCLUSION: Many negative studies in JKEM are inconclusive because they lack the adequate power to detect even large differences between groups. Therefore, it is imperative to consider power when interpreting the literature. When designing future research, power calculations should be performed to ensure sufficient patient recruitment to attain clinically meaningful results.
Data Interpretation, Statistical ; Dietary Sucrose ; Emergencies ; Emergency Medicine ; Patient Selection ; Prevalence ; Quality Assurance, Health Care ; Sample Size

OBJECTIVE: Somatosensory evoked potentials(SSEPs) have been used widely both experimentally and clinically to monitor the function of central nervous system and peripheral nervous system. Studies of SSEPs have reported the various recording techniques and patterns of SSEP. The previous SSEP studies used scalp recording electrodes, showed mean vector potentials which included relatively constant brainstem potentials(far-field potentials) and unstable thalamocortical pathway potentials(near-field potentials). Even in invasive SSEP recording methods, thalamocortical potentials were variable according to the kinds, depths, and distance of two electrodes. So they were regarded improper method for monitoring of upper level of brainstem. The present study was conducted to investigate the characteristics of somatosensory evoked field potentials(SSEFPs) of the cerebral cortex that evoked by hindlimb stimulation using ball electrode and the pathways of SSEFP by recording the potentials simultaneously in the cortex, VPL nucleus of thalamus, and nucleus gracilis. METHODS: In the first experiment, a specially designed recording electrode was inserted into the cerebral cortex perpendicular to the cortical surface in order to recording the constant cortical field potentials and SSEFPs mapped from different areas of somatosensory cortex were analyzed. In the second experiment, SSEPs were recorded in the ipsilateral nucleus gracilis, the contralateral ventroposterolateral thalamic nucleus(VPL), and the cerebral cortex along the conduction pathway of somatosensory information. RESULTS: In the first experiment, we could constantly obtain the SSEFPs in cerebral cortex following the transcutaneous electrical stimulation of the hind limb, and it revealed that the first large positive and following negative waves were largest at the 2mm posterior and 2mm lateral to the bregma in the contralateral somatosensory cortex. The second experiment showed that the SSEPs were conducted by way of posterior column somatosensory pathway and thalamocortical pathway and that specific patterns of the SSEPs were recorded from the nucleus gracilis, VPL, and cerebral cortex. CONCLUSION: The specially designed recording electrode was found to be very useful in recording the localized SSEFPs and the transcutaneous electrical stimulation using ball electrode was effective in evoking SSEPs. The characteristic shapes, latencies, and conduction velocities of each potentials are expected to be used the fundamental data for the future study of brain functions, including the hydrocephalus model, middle cerebral artery ischemia model, and so forth.
Animals ; Brain ; Brain Stem ; Central Nervous System ; Cerebral Cortex ; Electrodes ; Evoked Potentials, Somatosensory ; Extremities ; Hindlimb ; Hydrocephalus ; Ischemia ; Middle Cerebral Artery ; Peripheral Nervous System ; Rats* ; Scalp ; Somatosensory Cortex ; Thalamus ; Transcutaneous Electric Nerve Stimulation

OBJECTIVE: The activity of pulmonary tuberculosis has been usually detarmined by smear and culture of AFB in sputum and serial chest X ray. However it is sorntimes difficult to determine the activity of pulmonary tuberculosis by either. We have studied Gallium lung scan 4 HRCT in the patients with pulmonary tuberculosis to determine its activity and compared their diagnostic significance. METHODS: 67Gallium lung scan and HRCT were examined in 63 patients with pulmonary tuberculosis suspected by chest X ray and were compared each other with their possible diagnostic significance in determination of activity. The active pulmonary tuberculosis was defined by positive AFB smear and/ or culture in sputum and changes of findings in serial chest X ray. RESULTS: 1) Of 63 patients with pulmonary tuberculosis, 37 patients has been diagnosed active 9 patients were diagnosed by positive AFB smear in sputum, 20 patients by positive AFB culture in sputum and 8 patients by changes of findings in serial chest X ray. 2) In the 37 patients with active pulmonary tuberculosis, chest X ray revealed active pulmonary tuberculosis findings in 28 patients, inactive in 4 patients and undetermined in 5 patients. On the contrary, In the 26 patients with inactive pulmonary tuberculosis, the chest X ray revealed active pulmonary tuberculosis findings in 6 patients, inactive in 16 patients and undetermined in 4 patients. 3) 67Gallium lung scan showed positive uptake in 34 patients of the 37 patients with active pulmonary tuberculosis, but did not show any uptake at all in 26 patients with inactive pulmonary tuberculosis. 4) HRCT showed active findings in 36 patients of the 37 patients with pulmonary tuberculosis. And it showed active findings in 4 patients of the 26 patients with inactive pulmonary tuberculosis. CONCLUSION: The Gallium lung scan showed 82% of sensitivity and 8% of false negativity. And HRCT showed 97% of sensitivity and 15% of false positivity. In the aspect of laboratory examinations for the determination of activity in pulmonary tuberculosis the 67Gallium lung scan and the HRCT appeared useful.
Gallium* ; Humans ; Lung* ; Sputum ; Thorax ; Tuberculosis, Pulmonary*

Pulmonary pneumatoceles are air-filled thin-walled spaces within the lung and are rare in adult cases of pneumonia. We report the case of a 74-year-old male who was admitted with a cough and sputum production. He had been treated with oral dexamethasone since a brain tumorectomy 6 months prior. Contrast-enhanced computed tomography (CT) of the chest revealed a large pneumatocele in the right middle lobe and peripheral pneumonic consolidation. Bronchoalveolar lavage was performed; cultures identified extended-spectrum beta-lactamase (ESBL) producing Proteus mirabilis. A 4-week course of intravenous ertapenem was administered, and the pneumatocele with pneumonia resolved on follow-up chest CT. To the best of our knowledge, this is the first reported case of pulmonary pneumatocele caused by ESBL-producing P. mirabilis associated with pneumonia.
Adult ; Aged ; beta-Lactamases* ; Brain ; Bronchoalveolar Lavage ; Cough ; Dexamethasone ; Follow-Up Studies ; Humans ; Lung ; Male ; Mirabilis ; Pneumonia* ; Proteus mirabilis* ; Proteus* ; Sputum ; Thorax ; Tomography, X-Ray Computed