Effect of Application over Time for Each Type of Blending Tea on Bovine Tooth Coloration / 치위생과학회지

Background@#This study aimed to investigate the effect of selecting commercially available blending teas and applying them to bovine teeth on color change over time. @*Methods@#After selecting healthy bovine teeth, using a cutting-disc, 105 specimens with a dimension of 5×5×3 mm were prepared, and 15 specimens were distributed to each group. Black tea was used as a positive control, water was used as a negative control, and blended tea of five types was used as an experimental group. First, pH and buffering capacity were measured with a pH meter, and tooth color was determined using a spectrophotometer before immersion in the blending tea solution and 1, 5, 7, 14, and 21 days after immersion. Thereafter, the shape change of the enamel surface was observed using a scanning electron microscope, and SPSS ver.26 was used to analyze the color change. @*Results@#The average pH of the five blending teas in the experimental group was 3.78, and the pH of group 3 (strawberry rhubarb) was the lowest at 3.22. The pH levels of black tea and water were 5.19 and 7.30, respectively. The buffering capacity was the highest in group 3 at both pH levels of 5.5 and 7.0. The L*a*b* color change according to immersion time was the largest in group 4 (rooibos yellow flower), and the amount of color change was large in black tea and group 4. As a result of observing the enamel surface of bovine teeth, changes in the surface shape were noted in all groups immersed in the experimental solution for 21 days, except for water. @*Conclusion@#There was a significant difference between the experimental groups in terms of color change according to the immersion time, and color and enamel surface changes were observed in black tea and all experimental groups, except for water.

Efficacy of Implantable Bone Conduction Hearing Aids in Single-Sided Deafness / 대한이비인후과학회지

As the technology advances and bone conduction implant (BCI) use increases, implantable bone conduction hearing aids are regarded as a treatment method for single-sided deafness (SSD) and their efficacy on SSD must be discussed. Therefore, we organized the problems of SSD and types of implantable bone conduction hearing aids and explained their effectiveness in the treatment of SSD in terms of changes in 1) speech recognition in a noisy environment, 2) sound localization, 3) subjective satisfaction as assessed by questionnaire, and 4) tinnitus. Although bone conduction hearing aids do not significantly improve localization ability in SSD, they increase the ability to listen under noise, increasing subjective satisfaction. Tinnitus improvement was also reported. The active forms of BCI like MED-EL BONEBRIDGE®2 and Cochlear Osia®2 have been developed well. Based on these technological developments and effects, bone conduction hearing aids would be a good option for treatment option of SSD.

Measurement of Skull Size on Computed Tomography Images for Developing a Bone Conduction Headset Suitable for the Korean Standard Head Size

Background and Objectives@#We aimed to measure the head dimensions on computed tomography (CT) images, to compare them to directly measured head dimensions, and to predict a new parameter of bone thickness for aiding bone conduction implant (BCI) placement. @*Subjects and Methods@#We reviewed the facial and mandibular bone CT images of 406 patients. Their head sizes were analyzed using five parameters included in the 6th Size Korea project, and they were divided into age groups (ranging from the 10s to the 80s). We compared the head length, head width, sagittal arc, bitragion arc, and head circumference in the CT and Size Korea groups. We also added the parameter bone thickness for aiding BCI placement. @*Results@#All the head size parameters measured using CT were significantly smaller than those measured directly, with head length showing the smallest difference at 7.85 mm. The differences in the other four parameters between the two groups according to patient age were not statistically significantly different. Bone thickness had the highest value of 4.89±0.93 mm in the 70s and the lowest value of 4.10±0.99 mm in the 10s. Bone thickness also significantly correlated with head width (p=0.038). @*Conclusions@#Our findings suggested that the CT and direct measurements yielded consistent data. Moreover, CT enabled the measurement of bone sizes, including bone thickness, that are impossible to measure directly. CT measurements may complement direct measurements in the Size Korea data when used for developing bone conduction hearing devices (BCIs and headsets) for the Korean population.

Factors of Endoscopic Ultrasound-Guided Tissue Acquisition for Successful Next-Generation Sequencing in Pancreatic Ductal Adenocarcinoma

Background/Aims@#Recent advances in understanding the genetics of pancreatic ductal adenocarcinoma (PDAC) have led to the potential for a personalized approach. Several studies have described the feasibility of generating genetic profiles of PDAC with next-generation sequencing (NGS) of samples obtained through endoscopic ultrasound-guided tissue acquisition (EUS-TA). The aim of this study was to find the best EUS-TA approach for successful NGS of PDAC. @*Methods@#We attempted to perform NGS with tissues from 190 patients with histologically proven PDAC by endoscopic ultrasound-guided fine-needle aspiration and endoscopic ultrasound-guided fine-needle biopsy at Samsung Medical Center between November 2011 and February 2015. The medical records of these patients were retrospectively reviewed for parameters including tumor factors (size, location, and T stage), EUS-TA factors (needle gauge [G], needle type, and number of needle passes) and histologic factors (cellularity and blood contamination). The sample used for NGS was part of the EUS-TA specimen that underwent cytological and histological analysis. @*Results@#NGS could be successfully performed in 109 patients (57.4%). In the univariate analysis, a large needle G (p=0.003) and tumor located in the body/tail (p=0.005) were associated with successful NGS. The multivariate logistic regression analysis revealed that the needle G was an independent factor of successful NGS (odds ratio, 2.19; 95% confidence interval, 1.08 to 4.47; p=0.031). @*Conclusions@#The needle G is an independent factor associated with successful NGS. This finding may suggest that the quantity of cells obtained from EUS-TA specimens is important for successful NGS.

Four cases of coronavirus disease 2019 in the early stage of pandemic of South Korea: a single public hospital experience

In view of this pandemic, as of February 2020, South Korea has the second highest number of confirmed cases in the world. Herein, we report four confirmed coronavirus disease 2019 (COVID-19) cases in the early stage of the pandemic in South Korea and describe the identification, diagnosis, clinical course, and management, including one patient’s initial mild symptoms at presentation and their progression to pneumonia on day 21 of illness. Within 48 hours of hospitalization, all four patients underwent evaluation for initial laboratory parameters, COVID-19 polymerase chain reaction (PCR), and chest computed tomography (CT) findings. All four mild COVID-19 patients were discharged, and they were re-examined 14 days after discharge. Despite all four of them being asymptomatic, one patient was re-admitted after confirmation of COVID-19 through PCR viral nucleic acid detection. She could be discharged after 7 days with two subsequent negative COVID-19 PCR at 24-hour intervals. Patients with mild COVID-19 generally have normal follow-up chest CT scans after discharge, even if the early chest CT definitely indicates pneumonia. Re-hospitalized patients with COVID-19 PCR positive results after discharge were not related to her initial chest CT, lab, symptoms compared other three patients.

Development and Validation Study of the Internet Overuse Screening Questionnaire

OBJECTIVE: Concerns over behavioral and emotional problems caused by excessive internet usage have been developed. This study intended to develop and a standardize questionnaire that can efficiently identify at-risk internet users through their internet usage habits. METHODS: Participants (n=158) were recruited at six I-will-centers located in Seoul, South Korea. From the initial 36 questionnaire item pool, 28 preliminary items were selected through expert evaluation and panel discussions. The construct validity, internal consistency, and concurrent validity were examined. We also conducted Receiver Operating Curve (ROC) analysis to assess diagnostic ability of the Internet Overuse Screening-Questionnaire (IOS-Q). RESULTS: The exploratory factor analysis yielded a five factor structure. Four factors with 17 items remained after items that had unclear factor loading were removed. The Cronbach’s alpha for the IOS-Q total score was 0.91, and test-retest reliability was 0.72. The correlation between Young’s internet addiction scale and K-scale supported concurrent validity. ROC analysis showed that the IOS-Q has superior diagnostic ability with the Area Under the Curve of 0.87. At the cut-off point of 25.5, the sensitivity was 0.93 and specificity was 0.86. CONCLUSION: Overall, this study supports the use of IOS-Q for internet addiction research and for screening high-risk individuals.

Discontinuation Rate of Doxepin in Insomnia Patients / 정신신체의학

OBJECTIVES: We aimed to investigate the discontinuation rate and reasons of doxepin base prescription pattern in insomnia outpatients of psychiatry department of a university hospital. METHODS: 534 patients prescribed doxepin were screened. 201 patients were included and reviewed for their medical records retrospectively. The discontinuation rate and reasons of doxepin after 2 months of prescription were investigated. Patients were divided into three groups according to the prescription patterns. The initial group, prescribed doxepin as the first hypnotic, the add-on group, prescribed doxepin while maintaining existing hypnotics, and the switching group, prescribed doxepin after discontinuation of existing hypnotics. RESULTS: The discontinuation rate after 2 months of prescription of doxepin was 56.2%. There were significant differences in the discontinuation rate among three groups. The initial group had the highest while the add-on group had the lowest (p=0.018). In reasons for discontinuation of doxepin among three groups, lack of efficacy (p < 0.001) and adverse events (p < 0.001) were significantly higher in the add-on group. In the initial group, patient's refusal (p=0.022) and unknown or loss to follow up (p < 0.001) were significantly higher. CONCLUSIONS: The results of this study suggested that add-on is superior than switching method and gradual reduction of existing hypnotics is necessary to maintain doxepin treatment and prevent adverse events. Additional large scale prospective studies are needed to evaluate various factors and risks of discontinuation of doxepin.

Hospitalization Experience of Patients Admitted to Nursing Care Integrated Service Wards in Small and Medium-size General Hospitals / 간호행정학회지

PURPOSE: This study was conducted to identify meaning and essential structure of the hospitalization of patients in nursing care integrated service wards of small and medium-size general hospitals. METHODS: Experiential data were collected through in-depth interviews with 10 patients who had been hospitalized in nursing care integrated service wards of medium general hospitals. The main question was ‘Could you describe your hospitalization experience in nursing care integrated service wards of medium general hospitals?’, and collected data were analyzed using Colaizzi's Phenomenological Research Method. RESULTS: Four categories obtained were ‘Realize the system that is not established yet’, ‘Secure care services which are less of a psychological and financial burden’, ‘Thanks for care providers’, and ‘Confident of the hopeful system to desire to reuse in the future.’ CONCLUSION: Patients in nursing care integrated service wards of small and medium-size general hospitals were satisfied with the reduction of mental and financial burden caused by nursing and were thankful to nursing staff, who put a lot of efforts into nursing. But, at the same time, they were confused and inconvenienced by the services that were not yet completely established. To improve this situation, it is thought that institutional complements including development of a service standardization manual would be helpful.

Influence of the microwave sintering period on the 3 point flexural strength and shade of zirconia restoration / 대한치과재료학회지

In this study, we tried to confirm clinically applicable applicability by comparing the difference in 3 point flexural strength and shade of the prosthesis depending on microwave sintering time of dental CAD / CAM zirconia. 3 Point flexural strength specimens (n=30) and shade measurement specimens (n=28) were prepared and sintered at different sintering times. 3 point flexural strength and shade were measured and analyzed by independent t-test (α=0.05). Measurement result of 3 point flexural strength the average of short-term sintering (STS) was 245.47±29.89 MPa, the average of long-term sintering (LTS) was 284.27±31.56 MPa, and there was a statistically significant difference (p 0.05). The 3 point flexural strength of the zirconia restorations fabricated by short time and long time was high in long time sintering. However, other conditions may be required for clinical applications. Since the shade test did not show any significant color difference according to sintering time, it is considered to be sufficient for clinical application.

Postoperative negative pressure pulmonary edema following repetitive laryngospasm even after reversal of neuromuscular blockade by sugammadex: a case report / 대한마취과학회지

Laryngospasm, an occlusion of the glottis, can occur at any time during anesthesia, and is associated with serious perioperative complications such as hypoxia, hypercabia, aspiration, bronchospasm, arrhythmia, prolonged recovery, cardiac collapse, and eventually catastrophic death. Importantly, postoperative negative pressure pulmonary edema (NPPE) is a rare, but well described life-threatening complication related to acute and chronic upper airway obstruction. Sugammadex well known for affirmatively reducing the postoperative pulmonary complications associated with residual neuromuscular blockade may have an indirect role in triggering the negative intrathoracic pressure by raising a rapid and efficacious respiratory muscle strength in acute upper airway obstruction. Herein, we report a case of postoperative NPPE following repetitive laryngospasm even after reversal of rocuronium-induced neuromuscular blockade using sugammadex.

A Novel Model for Predicting Hepatocellular Carcinoma Development in Patients with Chronic Hepatitis B and Normal Alanine Aminotransferase Levels

BACKGROUND/AIMS: Hepatocellular carcinoma (HCC) can develop in chronic hepatitis B (CHB) patients with normal alanine aminotransferase (ALT) levels. Therefore, methods that can stratify an individual's HCC risk are needed. METHODS: A simple HCC risk score was developed from 971 patients with CHB who had elevated hepatitis B virus DNA levels (>2,000 IU/mL) with normal or mildly elevated ALT levels (<80 U/L). The score was validated from an independent cohort of 507 patients. RESULTS: A 4-point risk scale was developed, with HCC risk ranging from 0% to 17.8% at 5 years for the lowest and highest risk scores. The D2AS score had high area under the receiver operating curves (AUROCs) for predicting development of HCC at 3/5 years (0.895/0.884). The calculated AUROCs to predict the development of HCC at 3/5 years were 0.889/0.876 in the validation cohort, with 5-year HCC incidence rates ranging from 0% to 13.8% at 5 years for the lowest and highest risk scores. CONCLUSIONS: The D2AS risk score can play a valuable role in risk stratification and may be useful for guiding clinical decisions for enhanced surveillance or treatment to reduce the HCC risk in CHB patients with normal or mildly elevated ALT levels.

The prophylactic effect of dexamethasone on postoperative sore throat in prone position surgery / 대한마취과학회지

BACKGROUND: Sore throat and hoarseness are common complications after general anesthesia with tracheal intubation. The position for patients can affect the incidence of postoperative sore throat (POST) by causing displacement of the endotracheal tube. This study investigated the prophylactic effect of dexamethasone in prone position surgeries. METHODS: One hundred-fifty patients undergoing lumbar spine surgery (18-75 yr) were randomly allocated into the normal saline group (group P, n = 50), dexamethasone 0.1 mg/kg group (group D1, n = 50) or dexamethasone 0.2 mg/kg group (group D2, n = 50). The incidence and severity of POST, hoarseness, and cough were measured using direct interview at 1, 6, and 24 h after tracheal extubation. The severity of POST, hoarseness, and cough were graded using a 4-point scale. RESULTS: At 1, 6, and 24 h after extubation, the incidence of sore throat was significantly lower in group D1 (1 h; P = 0.015, 6 h; P < 0.001, 24 h; P = 0.038) and group D2 (1 h; P < 0.001, 6 h; P < 0.001, 24 h; P = 0.017) compared to group P. There were less number of patients in the groups D1 and D2 than group P suffering from moderate grade of POST at 1, 24 h after extubation. The incidence of hoarseness at 1, 6, and 24 h after extubation was significantly lower in groups D2 than group P (P < 0.001). There were no significant differences in the incidence of cough among the three groups. CONCLUSIONS: The prophylactic use of dexamethasone 0.1 mg/kg and 0.2 mg/kg in prone surgery reduces the incidence of postoperative sore throat and dexamethasone 0.2 mg/kg decreases the incidence of hoarseness.

Comparison of spinal anesthesia between the non-elderly and elderly patients

BACKGROUND: The clinical features of spinal anesthesia may differ between young and old patients because of the anatomical and physiological changes that occur with an increase in age. This study was performed retrospectively to compare the clinical aspects of spinal anesthesia between the non-elderly and elderly patients. METHODS: We investigated the medical records of 1,180 adult patients who received spinal anesthesia during a one-year period. They were divided into two groups on the basis of 65 years of age; the non-elderly patient group (Y group, n = 813) versus the elderly patient group (E group, n = 367). Pre-, intra-, and postoperative data related to spinal anesthesia were collected. The data about satisfaction and causes of dissatisfaction with the procedure were evaluated. RESULTS: There were significant differences between the two groups in terms of age, height, and weight, except for sex. Significantly more than two attempts at spinal puncture were performed in the E group (37.6%) than in the Y group (21.4%). There were no statistically significant differences in perioperative complications after spinal anesthesia between the two groups. There were no significant differences in the reported causes of dissatisfaction between the two groups. The rate of wanting to undergo spinal anesthesia in the future was 96.4% in the Y group and 97.5% in the E group, which showed no statistically significant difference. CONCLUSIONS: Although the elderly patients had to undergo more spinal puncture attempts, more than 90% of the elderly patients were satisfied with spinal anesthesia and wanted to undergo spinal anesthesia again for similar surgeries in the future.

Successful removal of a foreign body by endoscopic balloon dilatation at the colonic stricture / 영남의대학술지

Most ingested foreign bodies pass readily throughout intestinal tract if they reach the stomach. In some cases, foreign bodies may be impacted behind a luminal constriction but are rare in colon. Here, we report the case of a 59-year-old man who did laparoscopic anterior resection due to sigmoid colon cancer 2 years ago and ischemic colitis was repeated on the anastomosis site. He initially presented with symptoms of abdominal pain 3 months before and melena 1 day before admission. Abdomen computerized tomography showed a 3.2 cm segment of luminal narrowing of the proximal colon involving upstream foreign material stasis. Sigmoidoscopic approaches revealed near complete obstruction on the anal verge of 20 cm and scope passing failed. Balloon dilatations were done on the obstruction site four times all and a foreign body impacted above the obstruction site was removed by an alligator without any complications. The foreign body removed looks like plastic or a shell, about 20 mm in size.

Multiple exposures of sevoflurane in a patient with hepatic damage from crushing injuries: A case report

Sevoflurane, which has low solubility in blood, facilitates rapid induction and recovery. Sevoflurane is metabolized to hexafluoroisopropanol by cytochrome P450. Hexafluoroisopropanol has significantly less protein binding capability, does not accumulate and rapidly undergoes phase II biotransformation to form Hexafluoroisopropanol glucuronide, which is mostly excreted in the urine within 12 hours. Thus, the hepatotoxic potential of sevoflurane has been considered very low. However, there are many reports about hepatic toxicity after sevoflurane anesthesia. We report a case of a 21-year-old male who had high levels of aspartate transaminase and alanine transaminase with crushing injuries and had low hepatic dysfunction after 29 sevoflurane anesthesia treatments within three months.

Clinical features and outcomes of systemic amyloidosis with gastrointestinal involvement: a single-center experience

BACKGROUND/AIMS: The gastrointestinal (GI) tract often becomes involved in patients with systemic amyloidosis. As few GI amyloidosis data have been reported, we describe the clinical features and outcomes of patients with pathologically proven GI amyloidosis. METHODS: We identified 155 patients diagnosed with systemic amyloidosis between April 1995 and April 2013. Twenty-four patients (15.5%) were diagnosed with GI amyloidosis using associated symptoms, and the diagnoses were confirmed by direct biopsy. RESULTS: Among the 24 patients, 20 (83.3%) had amyloidosis light chain (AL), three (12.5%) had amyloid A, and one (4.2%) had transthyretin-related type amyloidosis. Their median age was 57 years (range, 37 to 72), and 10 patients were female (41.7%). The most common symptoms of GI amyloidosis were diarrhea (11 patients, 45.8%), followed by anorexia (nine patients, 37.5%), weight loss, and nausea and/or vomiting (seven patients, 29.2%). The histologically confirmed GI tract site in AL amyloidosis was the stomach in 11 patients (55.0%), the colon in nine (45.0%), the rectum in seven (35.0%), and the small bowel in one (5.0%). Patients with GI involvement had a greater frequency of organ involvement (p = 0.014). Median overall survival (OS) in patients with GI involvement was shorter (7.95 months; range, 0.3 to 40.54) than in those without GI involvement (15.84 months; range, 0.0 to 114.53; p = 0.069) in a univariate analysis. A multivariate analysis of prognostic factors for AL amyloidosis revealed that GI involvement was not a significant predictor of OS (p = 0.447). CONCLUSIONS: The prognosis of patients with AL amyloidosis and GI involvement was poorer than those without GI involvement, and they presented with more organ involvement and more advanced disease than those without organ involvement.

A Case of Invasion of Muscularis Propria of Gastric Inflammatory Fibroid Polyp

Inflammatory fibroid polyp (IFP) is an uncommon benign tumor and a proliferative disease localized to the submucosal area of the gastrointestinal tract. IFP has been detected more frequently with the increasing use of endoscopy. Histologically, gastric IFP is mostly limited to the submucosa, rarely invading the muscle layer. However, we experienced a case of gastric IFP invading the proper muscle layer. A 62-year-old man was referred for evaluation of epigastric pain. Contrast enhanced computed tomography of the abdomen and endoscopic examination revealed a stomach mass. IFP was histologically confirmed by surgical resection, and the patient was discharged without complication. IFP originating in the stomach that invades the muscularis propria is rare compared to that originating in the large or small intestine. The incidence of gastric IFP is relatively low. Invasion of the muscularis propria by IFP depends not only on the location but also the size of the IFP. There have been no published reports on the outcomes of gastric IFP invading the muscularis propria, therefore close follow-up of the present patient is important.

Effects of magnesium sulfate on remifentanil requirements for achieving hemodynamic stability during laparoscopy assisted distal gastrectomy

BACKGROUND: Magnesium is known to reduce the requirement of analgesic agents by blocking calcium channels that exist at the neuronal and neuromuscular junctions. However, former studies have shown inconsistent results regarding this concept. Therefore, we investigated the effects of magnesium on remifentanil requirements for achieving hemodynamic stabilization in patients undergoing laparoscopic gastrectomy. METHODS: Laparoscopic gastrectomy patients (n = 30) were randomly divided into two groups. Group M received 50 mg/kg of magnesium sulfate for 15 minutes prior to the induction of anesthesia. Then, 20 mg/kg/h of magnesium was administered during the operation time. Group N was administered the same amount of saline. Anesthesia was maintained with intravenous propofol and remifentanil injection. Vecuronium (0.1 mg/kg) was administered before intubation, and an additional 0.02 mg/kg was administered if a T1 twitch response was observed during surgery. Anesthetic time was standardized to provide an appropriate comparison of all patients. During 100 minutes, total anesthetic requirements and anesthetic requirements at every 10 minutes were analyzed. Postoperative pain was controlled with a patient controlled analgesia device. RESULTS: The remifentanil and vecuronium requirements during 100 minutes were significantly lower in Group M. There was no significant difference in propofol requirements between the two groups. No significant difference was observed in mean arterial pressure and heart rate. Postoperative VAS, PONV, or shivering also did not show any difference between the two groups. CONCLUSIONS: Magnesium reduced remifentanil and vecuronium requirements but not propofol requirements. Magnesium seems to have antinociceptic properties and reduces remifentanil requirements.

Comparison of i-gel(R) and LMA Supreme(R) during laparoscopic cholecystectomy / 대한마취과학회지

BACKGROUND: In laparoscopic surgical procedures, many clinicians recommend supraglottic airway devices as good alternatives to intubation. We compared the i-gel(R) (i-gel) and LMA Supreme(R) (Supreme Laryngeal Mask Airway, SLMA) airway devices during laparoscopic cholecystectomy regarding sealing pressure and respiratory parameters before, during, and after pneumoperitoneum. METHODS: Following Institutional Review Board approval and written informed consent, 93 patients were randomly allocated into the i-gel (n = 47) or SLMA group (n = 46). Insertion time, number of insertion attempts, and fiberoptic view of glottis were recorded. Oropharyngeal leak pressure (OLP), the use of airway manipulation, peak inspiratory pressure, lung compliance, and hemodynamic parameters were measured before, during, and after pneumoperitoneum. RESULTS: There were no significant differences between the two groups regarding demographic data, insertion time, fiberoptic view of glottis, and the use of airway manipulation. The gastric tube insertion time was longer in the i-gel group (20.4 +/- 3.9 s) than in the SLMA group (16.7 +/- 1.6 s) (P < 0.001). All devices were inserted on the first attempt, excluding one case in each group. Peak inspiratory pressure, lung compliance, and OLP changed following carbon dioxide pneumoperitoneum in each group, but there were no significant differences between the groups. CONCLUSIONS: Both the i-gel and SLMA airway devices can be comparably used in patients who undergo laparoscopic cholecystectomy, and they offer similar performance including OLP.

The effect of high concentration of magnesium with ropivacaine, gentamicin, rocuronium, and their combination on neuromuscular blockade / 대한마취과학회지

BACKGROUND: Magnesium, ropivacaine, gentamicin, and rocuronium block neuromuscular (NM) transmission by different mechanisms. Therefore, concurrent administration of these agents may induce prolonged muscle paralysis via synergistic interaction. This study investigated the efficacy and safety of NM block caused by the administration of high concentrations of magnesium in combination with ropivacaine, gentamicin, and rocuronium. METHODS: Eighty-three left phrenic nerve-hemidiaphragms from male SD rats (150-250 g) were hung in Krebs solution. Three consecutive single twitch tension (ST, 0.1 Hz) and one tetanic tension (TT, 50 Hz for 1.9 s) were obtained before drug application and at each new drug concentration. The concentration of MgCl2 and MgSO4 in Krebs solution was increased until an 80 to 90% reduction in ST was reached. To test the effects of combinations of NM agents, a Krebs solution was premixed with MgCl2 alone, MgCl2 and ropivacaine, or MgCl2, ropivacaine, and gentamicin. The concentration of ropivacaine, gentamicin, or rocuronium was then progressively increased until an 80 to 90% reduction in ST was reached. The effective concentrations were estimated with a probit model. RESULTS: The potency of MgCl2 was greater than that of MgSO4, and pretreatment with MgCl2 increased the potency of gentamicin and rocuronium. Unexpectedly, MgCl2 did not potentiate ropivacaine, and the potency of gentamicin and rocuronium failed to show an increase when premixed with 0.5 microM ropivacaine. CONCLUSIONS: The concomitant administration of high concentrations of magnesium and ropivacaine together with clinically relevant concentrations of gentamicin or rocuronium potentiated NM blockade but not with clinically relevant concentrations of ropivacaine.