The mediating role of flow in the relationship between simulation design and simulation educational satisfaction in korean nursing students: a cross-sectional study

BACKGROUND

In Korea, there has been recent interest in nursing simulation education. In nursing, simulation education has many advantages, such as improving nursing students' problem-solving and judgment skills. Simulation education satisfaction is an indicator for evaluating educational performance from the learners' perspective and an important criterion for the development and progress of nursing education. Therefore, based on NLN/Jeffries simulation theory, this study aims to identify the relationship between simulation design and educational satisfaction and to confirm the mediating effect of flow.

METHODS

This cross-sectional study was conducted using 143 fourth-year nursing students who had participated in classes using simulations at three universities in Seoul, Daegu, and Jeonbuk. Data were collected from April 24 to May 3, 2023. Demographic data, simulation design scale (SDS), flow in simulation, and the educational satisfaction scale in simulation were collected via an online questionnaire. The collected data were analyzed through t-test, ANOVA, Scheffé test, and Pearson's correlation coefficient using SPSS 25.0. The mediating effect of flow was analyzed through the three-stage mediation effect procedure using hierarchical regression analysis and the Sobel test.

RESULTS

The simulation educational satisfaction had a statistically significant positive correlation with simulation design (r = .65, p < .001) and flow (r = .47, p < .001), and simulation design was positively correlated with the flow (r = .55, p < .001). The simulation design had a statistically significant effect on flow, which was the mediating variable (β = 0.55, p < .001). Additionally, simulation design had a statistically significant effect on simulation educational satisfaction (β = 0.56, p < .001). The significance of the mediating effect of flow on the relationship between simulation design and simulation educational satisfaction was investigated using the Sobel test, and the mediating effect of flow was found to be statistically significant (Z = 5.36, p < .001).

CONCLUSION

The significance of the current study lies in its confirmation of the link between simulation design and simulation educational satisfaction, as well as the mediating function of flow. Nursing students can achieve simulation educational satisfaction through simulation-based education if simulation educators follow best practices that improve flow through well-organized simulation design.

Electroencephalographic features of elderly patients during anesthesia induction with remimazolam: a sub-study of a randomized controlled trial

BACKGROUND

Although remimazolam is used as a general anesthetic in elderly patients due to its hemodynamic stability, the electroencephalogram (EEG) characteristics of remimazolam are not well-known. The purpose of this study was to identify the EEG features of remimazolam-induced unconsciousness in elderly patients and compare them with propofol.

METHODS

Remimazolam (n=26) or propofol (n=26) were randomly administered for anesthesia induction in surgical patients. The hypnotic agent was blinded only to the patients. During the induction of anesthesia, remimazolam was administered at a rate of 6 mg/kg/h, and propofol was administered at a target effect-site concentration of 3.5 μg/ml. The EEG signals from 8 channels (Fp1,Fp2,Fz,F3,F4,Pz,P3,P4, referenced to A2, using the 10-20 system) were acquired during the induction of anesthesia and in the postoperative care unit. Power spectrum analysis was performed, and directed functional connectivity between frontal and parietal regions was evaluated using normalized symbolic transfer entropy. Functional connectivity in unconscious processes induced by remimazolam or propofol was compared with baseline. To compare each power of frequency over time of the two hypnotic agents, a permutation test with t statistic was conducted.

RESULTS

Compared to the baseline in the alpha band, the feedback connectivity decreased by an average of 46% and 43%, respectively, after the loss of consciousness induced by remimazolam and propofol (95% CI for the mean difference:-0.073 to -0.044 for remimazolam, P<0.001,-0.068 to -0.042 for propofol,P<0.001). Asymmetry in the feedback and feedforward connectivity in the alpha band was suppressed after the loss of consciousness induced by remimazolam and propofol. There were no significant differences in the power of each frequency over time between the two hypnotic agents (minimum q-value=0.4235).

CONCLUSIONS

Both regimens showed a greater decrease in feedback connectivity compared to a decrease in feedforward connectivity after loss of consciousness, leading to a disruption of asymmetry between the frontoparietal connectivity.

Erythrobacter oryzae sp. nov., isolated from rice paddy soil

Two novel bacterial strains, designated as COR-2T and CR-8, were isolated from paddy soil. These isolates were aerobic, Gram-stain-negative, non-spore-forming, non-motile, rod-shaped, and formed orange-coloured colonies. Phylogenetic analysis based on 16S rRNA gene sequences showed that two strains formed a clear phylogenetic lineage with the genus Erythrobacter. Strains COR-2T and CR-8 showed 99.9 % 16S rRNA gene sequence similarity. Both strains had the highest 16S rRNA gene similarity of 99.1-99.7 % to Erythrobacter colymbi TPW-24T, Erythrobacter donghaensis SW-132T and Erythrobacter tepidarius DSM 10594T, respectively. The genome of strain COR-2T comprised 3 559 918 bp and the genomic DNA G + C content was 67.7 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain COR-2T and its closely related species of the genus Erythrobacter were 79.3-85.5% and 24.1-29.1 %, respectively. The major respiratory quinone was Q-10, while the major fatty acids were C18 : 1  ω7c and C17 : 1  ω6c. The major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine, two unidentified phospholipids and eight unidentified lipids. Based on phylogenetic and phenotypic considerations, the two strains [COR-2T (type strain; = KACC 22941T=JCM 35529T) and CR-8 (= KACC 22945=JCM 35530)] are considered to represent novel species of the genus Erythrobacter, for which the name Erythrobacter oryzae sp. nov. is proposed.

A randomized, double-blind, single-dose, phase 1 study comparing the pharmacokinetics, pharmacodynamics, safety, and immunogenicity of denosumab biosimilar CT‑P41 and reference denosumab in healthy males

BACKGROUND

This study's objective was to demonstrate pharmacokinetic (PK) similarity and safety of denosumab biosimilar, CT‑P41, and United States-licensed reference denosumab (US-denosumab) in healthy male Asian adults, considering also pharmacodynamic (PD) outcomes.

RESEARCH DESIGN AND METHODS

This double-blind, two-arm, parallel-group, Phase 1 study randomized (1:1) healthy males to a single (60-mg) subcutaneous dose of CT‑P41 or US-denosumab. Primary endpoints were area under the concentration - time curve (AUC) from time zero to infinity (AUC0-inf), AUC from time zero to the last quantifiable concentration (AUC0-last), and maximum serum concentration (Cmax). PK equivalence was determined if 90% confidence intervals (CIs) for ratios of geometric least-squares means (gLSMs) were within the predefined 80-125% equivalence margin. Secondary PK, PD, safety, and immunogenicity outcomes were also evaluated.

RESULTS

Of 154 participants randomized (76 CT‑P41; 78 US-denosumab), 151 received study drug (74 CT‑P41; 77 US-denosumab). Primary and secondary PK results, PD results, safety, and immunogenicity were comparable between groups. Ninety percent CIs for ratios of gLSMs were within the predefined equivalence margin for AUC0-inf (100.4-114.7), AUC0-last (99.9-114.3), and Cmax (95.2-107.3).

CONCLUSIONS

Following a single dose in healthy males, CT‑P41 demonstrated PK equivalence with US-denosumab.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT06037395.

External validation of a pharmacokinetic model for target-controlled infusion of cefazolin as a prophylactic antibiotic

AIMS

This study aimed to evaluate the predictive performance of previously constructed cefazolin pharmacokinetic models and determine whether cefazolin administration via the target-controlled infusion (TCI) method may be possible in clinical practice.

METHODS

Twenty-five gastrectomy patients receiving cefazolin as a prophylactic antibiotic were enrolled. Two grams of cefazolin was dissolved in 50 mL of normal saline to give a concentration of 40 mg mL-1 . Before skin incision, cefazolin was administered using a TCI syringe pump, and its administration continued until the end of surgery. The target total plasma concentration was set to 100 μg mL-1 . Total and unbound plasma concentrations of cefazolin were measured in three arterial blood samples collected at 30, 60 and 120 min after the start of cefazolin administration. The predictive performance of the TCI system was evaluated using four measures: inaccuracy, divergence, bias and wobble.

RESULTS

Total (n = 75) and unbound (n = 75) plasma concentration measurements from 25 patients were included in the analysis. The pooled median (95% confidence interval) biases and inaccuracies were 6.3 (4.0-8.5) and 10.5 (8.6-12.4) for the total concentration model and -10.3 (-16.8 to -3.7) and 22.4 (18.2-26.7) for the unbound concentration model, respectively. All unbound concentrations were above 10 μg mL-1 .

CONCLUSION

Administration of cefazolin by the TCI method showed a clinically acceptable performance. Applying the TCI method by setting the total concentration as the target concentration rather than the unbound concentration is effective in maintaining a constant target concentration of cefazolin.

Search for Boosted Dark Matter in COSINE-100

We search for energetic electron recoil signals induced by boosted dark matter (BDM) from the galactic center using the COSINE-100 array of NaI(Tl) crystal detectors at the Yangyang Underground Laboratory. The signal would be an excess of events with energies above 4 MeV over the well-understood background. Because no excess of events are observed in a 97.7  kg·yr exposure, we set limits on BDM interactions under a variety of hypotheses. Notably, we explored the dark photon parameter space, leading to competitive limits compared to direct dark photon search experiments, particularly for dark photon masses below 4 MeV and considering the invisible decay mode. Furthermore, by comparing our results with a previous BDM search conducted by the Super-Kamionkande experiment, we found that the COSINE-100 detector has advantages in searching for low-mass dark matter. This analysis demonstrates the potential of the COSINE-100 detector to search for MeV electron recoil signals produced by the dark sector particle interactions.

Frequency and characteristics of patients with bispectral index values of 60 or higher during the induction and maintenance of general anesthesia with remimazolam

In Korea, the approved anesthetic regimen of remimazolam starts with 6 mg/kg/h or 12 mg/kg/h until loss of consciousness, followed by maintenance at 1-2 mg/kg/h. Some patients receiving remimazolam for general anesthesia experience occasional difficulty maintaining bispectral index (BIS) value ˂ 60. This retrospective study aimed to analyze the data from patients undergoing elective surgery under remimazolam based-general anesthesia to determine the frequency and physical characteristics of patients with BIS values ˂ 60. The criterion was established for patients with a poorly maintained BIS value < 60. The frequency and physical characteristics of patients who satisfied this criterion were investigated through their medical records. The modified Brice interview was conducted within 24 h after surgery. Among the 1500 patients included in the analysis, 61 (4.1%) met the criteria for BIS ˂ 60. Based on the modified Brice interview, none of the patients with poorly maintained BIS ˂ 60 complained of intraoperative awareness based on the modified Brice interview or exhibit specific physical characteristics. These patients accounted for less than 5% of the total population studied. Notably, physical characteristics alone are insufficient to predict such patients before surgery.

Detection efficiency calibration for an array of fourteen HPGe detectors

The CUP array of germanium (CAGe) is an array of fourteen high-purity germanium (HPGe) detectors. The detection efficiency of full-energy-peak emitted from the various samples assayed on the CAGe was calculated using the Monte Carlo simulation toolkit GEANT4. If the dead layer on the surface of the crystal is treated in the simulation as a continuous part of the active crystal, then the detection efficiency will be overestimated. Thus, the detection efficiency of the CAGe was adjusted using multi-nuclide source data and Monte Carlo simulations. The gamma spectra of the known activity source were obtained for each HPGe detector of the CAGe. The detection efficiency measured by the multi-source data was smaller than that of simulation data if the simulation treated the whole volume of germanium crystals as active for gamma detection. By optimizing the dead layers' thicknesses in the simulation, the detection efficiency calculated by the simulation could be matched to that of multi-source data.

Factors Influencing the Educational Needs and Nursing Intention Regarding COVID-19 Patient Care among Undergraduate Nursing Students

PURPOSE

This study examines final-year undergraduate nursing students to determine the educational needs for Coronavirus disease 2019 (COVID-19), knowledge of COVID-19, attitude toward COVID-19 patient care, and nursing intention toward COVID-19 patients.

METHODS

A structured questionnaire was used to collect data from 21 April to 6 May 2022. The participants included 144 final-year (4th year) undergraduate nursing students in Gangwon-do, Daegu-si, and Chungcheong-do. The SPSS/WIN 21.0 program was used to analyze the data; Pearson's correlation coefficients and multiple regression were further performed.

RESULTS

The attitude toward COVID-19 patient care (β = 0.38, p = 0.001), a cohabitant formerly infected with COVID-19, and the intention to study COVID-19 patient care (β = 0.16, p = 0.018) were found to influence nursing intention toward COVID-19 patients. These variables had a 27% explanatory power for nursing intention (F = 14.23, p < 0.001).

CONCLUSIONS

To foster undergraduate nursing students' nursing intention toward patients with emerging infectious diseases (EIDs), a program focused on cultivating a positive attitude toward EID patient care should be developed and implemented. The curriculum should further include education on EID patient care.

Multimorbidity adjusted years lost to disability rates calculated through Monte-Carlo simulation in Korea

OBJECTIVES

OBJECTIVES: To efficiently utilize limited health and medical resources, it is necessary to accurately measure the level of health, which requires estimating the multimorbidity-corrected burden of disease.

METHODS

METHODS: This study used 2015 and 2016 data from the National Health Insurance Service, and employed the list of diseases defined in a Korean study of the burden of disease, the criteria for prevalence, and the "cause-sequelae-health state" disease system. When calculating the years lost to disability (YLD), multimorbidity was corrected using Monte-Carlo simulation.

RESULTS

RESULTS: Correcting for multimorbidity changed YLD at all ages in Korea by -1.2% (95% confidence interval [CI], -24.1 to 3.6) in males and -12.4% (95% CI, -23.0 to 0.3) in females in 2015, and by -10.8% (95% CI, -24.1 to 4.6) in males and -11.1% (95% CI, -22.8 to 1.7) in females in 2016. The YLD rate for non-communicable diseases in males decreased more than that of other disease groups in both years, by -11.8% (95% CI, -19.5 to 3.6) and -11.5% (95% CI, -19.3 to -3.0), respectively. The overall YLD rate changed by -1.3% in the 5-year to 9-year age group, and the magnitude of this change remained similar until the 10-19-year age group, gradually decreased after 20 years of age, and steeply increased to more than 10% in those aged 60 and older.

RESULTS

CONCLUSIONS: Calculations of YLD should adjust for multimorbidity, as the disease burden can otherwise be overestimated for the elderly, who tend to exhibit a high prevalence of multimorbidity.

Predictive performance of pharmacokinetic models for target concentration-controlled infusion of cefoxitin as a prophylactic antibiotic in patients with colorectal surgery

We aimed to evaluate the predictive performance of previously constructed free (C_free) and total (C_total) cefoxitin pharmacokinetic models and the possibility of administering cefoxitin via the target‐controlled infusion (TCI) method in clinical practice. Two external validation studies (N = 31 for C_free model, N = 30 for C_total model) were conducted sequentially. Cefoxitin (2 g) was dissolved in 50 mL of normal saline to give a concentration of 40 mg mL⁻¹. Before skin incision, cefoxitin was infused with a TCI syringe pump. Target concentrations of free concentration and total concentration were set to 25 and 80 μg mL⁻¹, respectively, which were administered throughout the surgery. Three arterial blood samples were collected to measure the total and free plasma concentrations of cefoxitin at 30, 60 and 120 min, after the start of cefoxitin administration. The predictive performance was evaluated using four parameters: inaccuracy, divergence, bias and wobble. The pooled median (95% confidence interval) biases and inaccuracies were − 45.9 (−47.3 to −44.5) and 45.9 (44.5 to 47.3) for C_free model (Choi_F model), and − 16.6 (−18.4 to −14.8) and 18.5 (16.7 to 20.2) for C_total model (Choi_T_old model), respectively. The predictive performance of the newly constructed model (Choi_T_new model), developed by adding the total concentration data measured in the external validation, was better than that of the Choi_T_old model. Models constructed with total concentration data were suitable for clinical use. Administering cefoxitin using the TCI method in patients maintained the free concentration above the minimal inhibitory concentration (MIC) breakpoints of the major pathogens causing surgical site infection throughout the operation period.

Adjustment for Multimorbidity in Estimations of the Burden of Diseases Using Korean NHIS Data

The current multimorbidity correction method in the Global Burden of Disease studies assumes the independent occurrence of diseases. Those studies use Monte-Carlo simulations to adjust for the presence of multiple disease conditions for all diseases. The present study investigated whether the above-mentioned assumption is reasonable based on the prevalence confirmed from actual data. This study compared multimorbidity-adjusted years of lived with disability (YLD) obtained by Monte-Carlo simulations and multimorbidity-adjusted YLD using multimorbidity prevalence derived from National Health Insurance Service data. The 5 most common diseases by sex and age groups were selected as diseases of interest. No significant differences were found between YLD estimations made using actual data and Monte-Carlo simulations, even though assumptions about the independent occurrence of diseases should be carefully applied. The prevalence was not well reflected according to disease characteristics in those under the age of 30, among whom there was a difference in YLD between the 2 methods. Therefore, when calculating the burden of diseases for Koreans over the age of 30, it is possible to calculate the YLD with correction for multimorbidity through Monte-Carlo simulation, but care should be taken with under-30s. It is useful to apply the efficiency and suitability of calibration for multiplicative methods using Monte-Carlo simulations in research on the domestic disease burden, especially in adults in their 30s and older. Further research should be carried out on multimorbidity correction methodology according to the characteristics of multiple diseases by sex and age.

The contribution of form repetition to listeners' expectation of givenness in online reference resolution

Although it is clear that unaccented referring expressions are associated with given information in a discourse (Dahan et al., 2002), it is less clear what aspects of givenness are relevant. We examine whether listeners' expectation of givenness depends on repetition of a referring expression or on contextual evocation of a referent. The results from two visual world eye-tracking experiments suggest that for interpretation, listeners associated reduced prominence with a repeated referring expression. Listeners expect previously evoked referents to be candidates for reduced referring expressions only when they are referred to with the exact same referential form. The data also suggest that when referents are referred to with different referential forms across utterances, accenting facilitates linking those forms for co-reference.

Development of a new pharmacokinetic model for target-concentration controlled infusion of vancomycin in critically ill patients

The aim of this prospective study was to construct a new pharmacokinetic model of vancomycin for target-concentration controlled infusion (TCI). As the first loading dose, 25 mg/kg of vancomycin was administered during 60-90 min. Arterial blood samples were obtained at pre-set intervals to measure the serum concentrations of vancomycin. Population pharmacokinetic analysis was performed using the NONMEM software (ICON Development Solutions). In total, 197 serum concentration measurements from 22 patients were used to characterise the pharmacokinetics of vancomycin. A three-compartment mammillary model best described the pharmacokinetics of vancomycin in critically ill patients. The ideal body weight was a significant covariate for the central and slow peripheral volume of distribution. The weight and age converted to categorical variables at a cut-off of 65 years were a significant covariate for the clearance. Based on the results of stochastic simulation, the TCI method maintained the therapeutic concentration range for the longest duration. In addition, assuming that vancomycin was administered by the TCI method for 7 days, the dose was reduced by about 15% compared with the standard administration methods. The daily area under the curve values were maintained between 500 mg·h/L and 600 mg·h/L. TCI has the potential to become a new infusion method for patient-tailored dosing in critically ill patients. To administer vancomycin via TCI in clinical practice, the newly constructed pharmacokinetic model should undergo proper external validation.

Safety climate, nursing organizational culture and the intention to report medication errors: A cross-sectional study of hospital nurses

Background & Aim: Medication errors are the second most common accident after the fall accident in hospitals. Medication errors are a threat to patient safety. It is important to find the cause of such errors so that we can reduce them. However, the rate of medication error reporting is low. This study aimed to explore the factors associated with the intention to report medication errors among general hospital nurses. Methods & Materials: A cross-sectional study design was used. The participants were 171 registered nurses working in 4 general hospitals in South Korea. Convenient random sampling was used to select participants. Data were collected using mobile self-report structured questionnaires that covered general characteristics, medication errors and the intention to report them, the safety climate, and the nursing organizational culture. The data collection period was from March 14 to April 6, 2018. The data were analyzed by descriptive statistics, the Pearson correlation coefficients, and multiple regression analysis. Results: The mean scores of the intention to report medication errors and safety climate were 5.20±1.40 and 3.04±0.47, respectively. Each mean score of nursing organizational culture types was hierarch-oriented culture 3.63±0.51, relation-oriented culture 3.13±0.69, task-oriented-culture2.99±0.56, and innovation-oriented culture 2.85±0.67. Significant factors associated with the intention to report medication errors were the safety climate (β=.26, p=.001), a task-oriented culture (β=.16, p=.023), educational level (β=-.19, p=.006), the experience of medication errors (β=.19, p=.006), and male (β=-.18, p=.011). They accounted for 25% of the intention to report medication errors. Conclusion: This study found that the safety climate of the hospital, task-oriented culture of the nursing organization, education level, experience of medication errors, and gender associated with the intention to report medication errors. It is necessary to find ways to improve the safety climate of the hospital and the task-oriented culture of the nursing organization and establish a strategy for improving the intention to report medication errors for male nurses and nurses with medication errors.

Development of a new pharmacokinetic model for target-concentration controlled infusion of cefoxitin as a prophylactic antibiotic in colorectal surgical patients

AIMS

There are several limitations to the existing method of administering cefoxitin as a prophylactic antibiotic, and the limitations may be overcome by applying the target-concentration controlled infusion (TCI) method. Population pharmacokinetic parameters are required to administer cefoxitin by the TCI method. The aim of this study was to construct a new pharmacokinetic model of cefoxitin for the TCI method in colorectal surgical patients.

METHODS

In patients undergoing colorectal surgery, 2 g of cefoxitin was dissolved in 50 mL of saline and administered for 10 minutes prior to skin incision. Arterial blood samples were obtained at preset intervals to measure the total and free plasma concentrations of cefoxitin. Population pharmacokinetic analysis was performed using NONMEM software (ICON Development Solutions, Dublin, Ireland). Additionally, stochastic simulation was used to indirectly evaluate the effectiveness of the two administration methods (standard method vs TCI).

RESULTS

In total, 297 plasma concentration measurements from 31 patients were used to characterize the pharmacokinetics of cefoxitin. A three-compartment mammillary model described the pharmacokinetics of cefoxitin. Body weight and creatinine clearance were significant covariates for clearance. The stochastic simulation showed that when compared with the standard method, the TCI method has a significantly higher fraction of time that the free concentration of cefoxitin is maintained above the minimum inhibitory concentration (P < .001).

CONCLUSIONS

TCI has the potential to become a new infusion method for patient-tailored dosing in surgical patients. To administer cefoxitin via TCI in clinical practice, the newly constructed pharmacokinetic model should undergo proper external validation.

Performance of the Surgical Pleth Index and Analgesia Nociception Index in Healthy Volunteers and Parturients

Various commercially available nociception devices have been developed to quantify intraoperative pain. The Surgical Pleth Index (SPI) and Analgesia Nociception Index (ANI) are among the analgesic indices that have been widely used for the evaluation of surgical patients. This study aimed to evaluate the clinical performance of the SPI and ANI in conscious healthy volunteers and parturients. Ten healthy volunteers and 10 parturients participated in this study. An algometer was used to induce bone pain in the volunteers until they rated their pain as five on the numerical rating scale (NRS); this procedure was repeated during the administration of remifentanil or normal saline. The study comprised two periods, and the volunteers were infused with different solutions in each period: normal saline during one period and remifentanil during the other in a randomized order. The parturients’ SPI and ANI data were collected for 2 min when they rated their pain levels as 0, 5, and 7 on the NRS, respectively. Both the SPI and ANI values differed significantly between NRS 0 and NRS 5 (P < 0.001) in the volunteers, irrespective of the solution administered (remifentanil or normal saline). At NRS 5, the SPI showed similar values, irrespective of remifentanil administration, while the ANI showed significantly lower values on remifentanil administration (P = 0.028). The SPI and ANI values at NRS 5 and NRS 7 did not differ significantly in the parturients (P = 0.101 for SPI, P = 0.687 for ANI). Thus, the SPI and ANI were effective indices for detecting pain in healthy volunteers and parturients.

Population pharmacokinetic analysis of ropivacaine extended-release from a temperature-responsive hydrogel in rats

Therapeutic agents with a short half-life need to be administered frequently to achieve sustained and effective concentrations. This could be accomplished using sustained drug delivery technology. PF-72 (TGel Bio, Inc., Seoul, Korea) is a drug delivery system based on a powder obtained from lyophilisation of a reverse thermal hydrogel, which could assist in achieving prolonged pain relief if mixed with an anaesthetic and injected into the incision site following surgery. The pharmacokinetic parameters related to the absorption of the local anaesthetic ropivacaine delivered using this hydrogel were quantified. Ten rats were divided into two groups (n = 5 each), and equal doses (4 mg/kg) of different formulations were subcutaneously injected into the abdomen. The experimental group received PF-72 mixed with 0.75% ropivacaine, and the control group received 0.75% ropivacaine. Blood was collected at specific times to measure the plasma concentration of ropivacaine. Population pharmacokinetic analysis was performed using NONMEM VII level 4 (ICON Development Solutions, Dublin, Ireland). The one-compartment absorption model, which combines zero-order absorption and first-order absorption, was used to describe the change in ropivacaine plasma concentration over time. The type of formulation was a significant covariate for zero-order absorption duration (experimental group, 92.9 min; control group, 60.5 min). The addition of PF-72 to 0.75% ropivacaine increased the duration of absorption into the blood, suggesting a longer lasting effect of the analgesic injected into the surgical wound.

The relationship between leader-member exchange and intention to stay in Korean nurses: Focusing on the mediating role of compassion satisfaction

Background & Aim: Recently, there has been a growing interest in the nursing shortage. Although the number of nursing school has been increased and refreshment programs for inactive nurses have been run, the lack of nurses is still a common problem in Korea. Considering the importance of nurses' role in hospitals, it is important to investigate how to reduce turnover rates. This study aimed to investigate the mediating role of compassion satisfaction on the relationship between leader-member exchange (LMX) and intention to stay in Korea. Methods & Materials: A cross-sectional study design was used. Data were collected from 131 nurses from three university hospitals in South Korea. A demographic data form, LMX-7 scale, compassion satisfaction of the professional quality of life scale, and the nurses’ retention index were used to collect data. Results: Our results indicate that LMX has a positive effect on compassion satisfaction and intention to stay and compassion satisfaction has a positive effect on the intention to stay. In addition, compassion satisfaction was found to mediate the impact of LMX on the intention to stay. Conclusion: The present study is significant in that it confirms the relationship between LMX and intention to stay and the mediating role of compassion satisfaction. The nursing managers should pay attention to find ways to improve LMX and compassion satisfaction in hospitals in order to increase nurses’ intention to stay.

An allometric pharmacokinetic model and minimum effective analgesic concentration of fentanyl in patients undergoing major abdominal surgery

BACKGROUND

We aimed to characterise the population pharmacokinetics of fentanyl in adults and to determine the minimum effective concentration (MEC) and minimum effective analgesic concentration (MEAC) of i.v. fentanyl in patients after major abdominal open surgery.

METHODS

In the pharmacokinetic study, subjects received an intravenous bolus of fentanyl 100 μg during operation, and arterial blood was sampled at pre-set intervals. In addition, data from previously published fentanyl pharmacokinetic studies were incorporated to build a pharmacokinetic model. In the MEAC study, subjects were asked to rate their pain every 10 min using a VAS (0=no pain, 10=most severe pain) in the PACU. The first blood sample was obtained when wound pain was rated as ≥3 at rest or ≥5 during compression. Then, fentanyl 50 μg was administered every 10 min until the pain intensity had decreased to <3 at rest and <5 during compression, at which point the second blood was sampled and the first MEAC of fentanyl was measured. The same procedure was repeated to obtain a third sample (MEC) and a fourth sample (second MEAC).

RESULTS

In the population pharmacokinetic study (n=95), the plasma concentration of fentanyl over time was well-described by the three-compartment mammillary model using an allometric expression. The V1, V2, V3, Cl, Q1, and Q2 of a 70 kg subject were 10.1, 26.5, 206 L, 0.704, 2.38, and 1.49 L min^-1, respectively. In the MEAC study (n=30), the median (inter-quartile range) MEC and MEAC were 0.72 (0.58-1.05) ng ml^-1, and 0.99 (0.76-1.28) ng ml^-1, respectively.

CONCLUSION

These results provide a scientific basis for the use of fentanyl for acute postoperative pain management in surgical patients.

CLINICAL TRIAL REGISTRATION

KCT0003273 (http://cris.nih.go.kr).

A modified method of measuring plasma volume with indocyanine green: reducing the frequency of blood sampling while maintaining accuracy

Among various methods for measuring the plasma volume (PV), the indocyanine green (ICG) dilution technique is a relatively less invasive method. However, the ICG method is rather cumbersome because 10 blood samples need to be obtained within a short time after ICG administration. Thus, reducing the frequency of blood sampling while maintaining the accuracy would facilitate plasma volume measurement in clinical situations. We here developed a modified method to measure plasma volume using 2260 ICG plasma concentration data from 115 surgical patients. The mean relative error (MRE) and the percentage of cases with relative error (RE) greater than 5% in total (PRE) were used to quantify the difference between plasma volumes obtained by the original and modified methods. RE was determined as follows. RE(%) = (PV obtained by original method (PV_original)-PV obtained by modified method (PV_modified))/PV_original × 100. PV_modified was assumed to be equal to PV_original when the RE was < 5%. When the number of samples selected for the plasma volume estimation was 4 or less, the PRE was mostly 10% or more. Five out of the 10 blood samples (order: 1st, 2nd, 3rd, 9th, and 10th) showed similar accuracies with the plasma volume obtained by the original method (original: 2.72 ± 0.64 l, modified: 2.72 ± 0.65 l). This modified method may be able to aptly replace the original method and lead to a wider clinical application of the ICG dilution technique. Further validation is needed to determine if the results of this study may be applied in other populations.