The Development of Customized Overcrowding Index for an Emergency Department

PURPOSE: Emergency department (ED) overcrowding results in loss in timely, effective medical care, as well as in social and economical efficiency. This paper proposes a new overcrowding index to reduce and to prevent these losses. METHODS: We investigated the real-time situation of the emergency department in a major Korean hospital, compared to existing indices and to extracted factors to develop a new, customized overcrowding index based on the flow of patients, a reflection of emergency room conditions. We developed 3 indices, FFOI (Front Flow Overcrowding Index), BFOI (Back Flow Overcrowding Index), and TFOI (Total Flow Overcrowding Index). Each index was applied to test the period from 10 September 2007 to 16September 2007. We extracted values of each index at 3- hour intervals and estimated how they reflected the overcrowding situation compared with basic overcrowdingindices. We used the correlation coefficient and Kullback- Leiblur (KL) distance as the basis for measurement. RESULTS: Existing indices are emergency department work index (EDWIN), national emergency department overcrowding scale (NEDOCS), and real-time emergency analysis of demand indicator (READI) work score (WS). EDWIN and READI did not reflect accurately the overcrowding situation. Some factors extracted from NEDOCS and WS were not suited to the emergency department. We solved these problems by develop in new indices. CONCLUSION: In conclusion, the new indices are more effective and descriptive than the existing indices with respect to correlation to crowdedness in the emergency department. In the future, the new, customized overcrowding index will become more descriptive if the necessary data is gathered in real time and more effectively verified by the medical staffs and patients.

Continuous Infraclavicular Brachial Plexus Block Using Retrograde Insertion of an Epidural Catheter with Stylet through the Axilla / 대한마취과학회지

BACKGROUND: The continuous infraclavicular brachial plexus block (BPB) has many merits compared to other approaches. However, due to complications and the discomfort felt by patients during the procedure, it has not gained much in popularity. We assumed that the neurovascular sheath is one compartment and placed the catheter deeply into the sheath, as used in the infraclavicular approach, through the axilla. METHODS: Patients scheduled for surgery were paired according to their diagnoses and sites of surgery. Thirty-two patients were randomly chosen and divided into two groups. Selander's continuous axillary BPB was performed in the axillary group. In the infraclavicular group, we inserted an epidural catheter with a stylet deeper into the site just medial to the coracoid process using a C-arm and nerve stimulator. RESULTS: In the infraclavicular group, sensory and motor block of the musculocutaneous nerve and the quality of BPB was superior to those of the axillary group (P < 0.05). The average depth of the catheter from the skin was 14 +/-1.5 cm. CONCLUSIONS: Continuous infraclavicular BPB can cause no more discomfort as Selander's continuous axillary approach. Furthermore, it may improve the quality of block and reduce the amount of local anesthetic used.

Experimental Radiofrequency Lesion Size Utilizing Different Parameters and Neuropathologic Correlation on the Peripheral Nerve / 대한마취과학회지

BACKGROUND: Radiofrequency (RF) lesioning is one of the most frequently used neurolytic techniques for the relief of pain. Technical advances enables one to make a more reliable and reproducible lesion production. If the size at different parameters is known, the maximal effects and reduction of the side effects could be achieved. However, its size can not be measured systematically using thermocouple (TC) electrodes. 'Differential selection of pain fibers' was proposed but there was not any neuropathologic evidence. We studied pathologic changes produced with various sizes and shapes of electrodes using different parameters. METHODS: Using fresh egg white, RF lesions were produced by four different electrodes at 65, 70, 75, 80 and 90degreesC. At each temperature, Photographs were taken at 10, 20, 30, 40, 50, 60, 90 and 120 seconds. Using the sciatic nerve of the rats, we performed RF lesioning utilizing two different electrodes at 70, 80 and 90degreesC and dissected them 1, 7, and 30 days after treatment. The pathologic changes of lesions were studied and analyzed by applying a quantitative experimental scoring system on the light and electron microscopy (LM and EM). RESULTS: The lesion size increased with a higher temperature and larger electrode. Among the electrodes with the same thickness, the lesion size with the longer electrode was larger than the shorter one. In a histopathologic study, there were significant changes with time, but no significant changes with different electrode and temperature. On electron microscope (EM), large myelinated fibers were relatively intact on RF lesion of 80degreesC after 1 day. 7 days after treatment, there were significant inflammatory cell infiltration and axonal regeneration. At 30 days after the same treatment, there were relatively large amount of small myelinated fibers and unmyelinated fibers. CONCLUSIONS: We measured the lesions systematically with different parameters expecting the result can be used as the reference for the RF lesion. There were no histopathologic differences on LM at different electrodes and temperatures. But we found the evidence of 'differential selection of pain fibers' with 22 gauge electrode at 80degreesC. And also we found the axonal regeneration as early as 1 week later. We learned the neuropathic pain can be induced by pathologic changes, such as bleb formation, inflammatory cell infiltration and predominance of small myelinated and unmyelinated fibers.

The Spectral Analysis of EEG according to Change in the Concentration of Isoflurane / 대한마취과학회지

BACKGROUND: Adequate depth of anesthesia requires a sufficient amount of the agent to secure unconsciousness and other components of anesthesia as needed for that particular surgical procedure, without jeopardizing vital organ functions. To evaluate the relationship of depth of anesthesia to EEG, we studied the effects of increasing minimum alveolar concentration (MAC) of isoflurane (arousal, 1, 1.3, 1.5 MAC) on power spectral analysis of the EEG. METHODS: To determine 1 MAC, we studied sixty patients undergoing general anesthesia who were randomly allocated to receive isoflurane at several predetermined end-tidal concentration. A minimum of 15 min was allowed between induction and skin incision to allow steady state condition. Patients were observed for gross purposeful movement for 60 seconds after incision. The MAC was calculated using maximum likelihood solution to a logistic regression model. Another forty patients were randomly allocated to have their EEGs recorded. General anesthesia was induced with oxygen and isoflurane only. After loss of consciousness, succinylcholine 1.5 mg/kg was given and intubation followed. The EEG was recorded awake and after 15 min at steady state conditions of 1, 1.3 and 1.5 MAC isoflurane had been achieved. Spectral edge frequency 95% (SEF95), median spectral frequency (MSF), total power (TP) and relative power in the delta, theta, alpha and beta band were calculated. RESULTS: The MAC of isoflurane was 1.21 vol% (20 - 40 years) and 1.09 vol% (40 - 60 years). The distribution of spectral EEG indices of the EEGs were established and compared. The threshold value of SEF95 14 Hz to differentiate between arousal and 1.3 and 1.5 MAC had a sensitivity of 60.5% (1.3 MAC), 71% (1.5 MAC) and specificity of 74.4% (1.3 and 1.5 MAC) and that of MSF 5 Hz had a sensitivity of 71% (1.3 MAC), 81.5% (1.5 MAC) and specificity of 48% (1.3 MAC), 48.8% (1.5 MAC). CONCLUSIONS: With regard to the dose-related decrease in SEF95 and MSF under increasing end- expiratory concentrations of isoflurane as described in the present study, future studies may have todetermine whether EEG feedback control of volatile anesthetic administration may be used successfully. It seems that if neglected parts by MSF and SEF95, which are really true values are considered in the future studies, those would increase the sensitivity and specificity of EEG could be used as tool for determining depth of anesthesia.

A Comparison of the Size and Shape of Radiofrequency Lesions Produced by Different Temperatures Using Straight and Curved Electrodes / 대한마취과학회지

BACKGROUND: Understanding the electrophysiology of radiofrequency (RF) lesions and determining the size and shape of RF lesions is important for reducing side effects when applied to patients in a clinical setting. We compared the shape and size of RF thermocoagulation produced by straight and curved 20-gauge electrodes and considered its application in clinical settings. METHODS: The white from a fresh hen's egg was warmed to 37oC and placed in a rectangular glass container. Straight and curved 20-gauge electrodes were immersed. The transparency of the egg white and the glass container made it possible to photograph the changes in size of the RF lesions over time. We applied thermocoagulation for 60 seconds at 70, 80, and 90oC. Photographs were taken at 60 seconds. We measured the maximal size of the lesions. A two-way statistical analysis of variance was performed. RESULTS: The thermocoagulations were started at the junction of the insulated and uninsulated portion of the electrode and did not extended beyond the tip. The thermocoagulation size was 4.2 +/- 0.8 at 70oC, 6.1 +/- 2.9 at 80oC and 6.1 +/- 1.9 at 90oC using the 20-gauge, 10 mm active tip, straight electrode and 4.5 +/- 1.1 at 70oC, 7.2 +/- 1.9 at 80oC and 7.9 +/- 2.7 at 90oC using the 20-gauge, 10 mm active tip, curved electrode. There was no observable difference in the size of the lesions produced by the straight and curved electrodes. CONCLUSIONS: We found that temperature was the more important factor in determining lesion size. When the temperature setting is the same, lesions produced by straight and curved electrode of the same gauge are also same size. Therefore the choice of straight or curved electrode should be made to optimize ease of handling and ensure proper location of the electrode tip.

Effects of Variable Infusion Rates of Propofol on Arterial Baroreflex Sensitivity / 대한마취과학회지

BACKGROUND: Induction of anesthesia with propofol caused a decrease in arterial blood pressure and systemic vascular resistance. This effects of propofol on the circulation can be more clarified by studying cardiovascular control mechanism such as baroreflex sensitivity during variable rate infusion of propofol. METHODS: The effects of three infusion rates of propofol (3, 6, 12 mg/kg/hr) to supplement 66% nitrous oxide in oxygen anesthesia on baroreflex sensitivity were studied and compared with awake value in 80 ASA I or II patients (20-55 years old, n=20 in each group). Baroreflex control of heat rate was studied by pertubing the patients' arterial pressure with 100 microgram of phenylephrine in each three infusion rates of propofol which was maintained at least 30 min without any surgical stimulation. RESULTS: Baroreflex slope representing baroreflex sensitivity among three infusion rates of propofol did not show any significant differences. The slope of each infusion rate was 8.4+/-0.7 at awake, 8.9+/- 1.7 at 3 mg/kg/hr, 8.0+/-1.3 at 6 mg/kg/hr, 7.2+/-1.0 at 12 mg/kg/hr, respectively. But, resetting of the reflex occured at low heart rates. CONCLUSIONS: Usual propofol-nitrous oxide-oxygen anesthesia was not associated with impairment of baroreflex sensitivity, but showed reflex resetting at low heart rates.

Two Cases of Complete Remission of Gestational Trophoblastic Disease in Oophorectomized Patients / 대한부인종양콜포스코피학회잡지

Although chemotherapy remains to be the mainstay of treatment of trophoblastic disease, hysterectomy has been performed as the primary management of nonmetastatic trophoblastic disease who desire sterilization and for uterine disease resistant to chemotherapy. Clinically, the documentation of disease regression is provided by serial quantitative serum beta-hCG assays and the persistent disease may be indicated when the serum beta-hCG values rise for 2 weeks or plateau for 3 weeks or more. Because of similarity in molecular structure, the confounding effect of an elevated LH on beta-hCG assessment in castrated women after treatment for trophoblastic disease has been documented. This LH cross-reactivity may be suspected in women with bilateral oophorectomy demonstrating persistent low levels of beta-hCG. It is particularly true when the assay is perfo-rmed by conventional polyclonal radioimmunoassay. We have experienced two cases of nonmetastatic trophoblastic disease whose serum beta-hCG assay plateaued at a low level after total abdominal hysterectomy with bilateral salpingo-oophorectomy and chemotherapy. Clinical and radiologic work-ups were done for metastatic lesion in dose patients, but the results were negative. The quantitative LH assays (Serono LH MAIAclone kit, Roma, Italy) were performed with the sera obtained from the patients; the results were 37 and 31 mIU/ml (1st IRP) with beta-hCG of 14 and 13 mIU/ml (1st IRP), respec-tively. With the initiation of oral estrogen replacement thrapy to those patients, the quantitative beta-hCG values fell below 5 mIU/ml (1st IRP) and they remained in complete chemical remission without any additional chemotherapy for one year. The persistant low titers of beta-hCG in those patients were considered to be result of LH cross-reactivity on beta-hCG assessment. It is concluded that whenever the assay of beta-hCG shows persistent low titers in the oophorectomized patient for treatment of trophoblastic disease, LH cross-reactivity should be suspected.

Two Cases of Complete Remission of Gestational Trophoblastic Disease in Oophorectomized Patients / 대한부인종양콜포스코피학회잡지

Although chemotherapy remains to be the mainstay of treatment of trophoblastic disease, hysterectomy has been performed as the primary management of nonmetastatic trophoblastic disease who desire sterilization and for uterine disease resistant to chemotherapy. Clinically, the documentation of disease regression is provided by serial quantitative serum beta-hCG assays and the persistent disease may be indicated when the serum beta-hCG values rise for 2 weeks or plateau for 3 weeks or more. Because of similarity in molecular structure, the confounding effect of an elevated LH on beta-hCG assessment in castrated women after treatment for trophoblastic disease has been documented. This LH cross-reactivity may be suspected in women with bilateral oophorectomy demonstrating persistent low levels of beta-hCG. It is particularly true when the assay is perfo-rmed by conventional polyclonal radioimmunoassay. We have experienced two cases of nonmetastatic trophoblastic disease whose serum beta-hCG assay plateaued at a low level after total abdominal hysterectomy with bilateral salpingo-oophorectomy and chemotherapy. Clinical and radiologic work-ups were done for metastatic lesion in dose patients, but the results were negative. The quantitative LH assays (Serono LH MAIAclone kit, Roma, Italy) were performed with the sera obtained from the patients; the results were 37 and 31 mIU/ml (1st IRP) with beta-hCG of 14 and 13 mIU/ml (1st IRP), respec-tively. With the initiation of oral estrogen replacement thrapy to those patients, the quantitative beta-hCG values fell below 5 mIU/ml (1st IRP) and they remained in complete chemical remission without any additional chemotherapy for one year. The persistant low titers of beta-hCG in those patients were considered to be result of LH cross-reactivity on beta-hCG assessment. It is concluded that whenever the assay of beta-hCG shows persistent low titers in the oophorectomized patient for treatment of trophoblastic disease, LH cross-reactivity should be suspected.