Comparison of preoxygenation efficiency measured by the oxygen reserve index between high-flow nasal oxygenation and facemask ventilation: a randomised controlled trial.

BACKGROUND: High-flow nasal oxygenation and the oxygen reserve index (ORI), which is a non-invasive and innovative modality that reflects the arterial oxygen content, are used in general anaesthesia. This study compares the preoxygenation efficiency (measured by the ORI) of high-flow nasal oxygenation and facemask ventilation during the induction process. METHODS: This single-centre, two-group, randomised controlled trial included 197 patients aged ≥ 20 years who underwent orotracheal intubation for general anaesthesia for elective surgery. The patients were randomly allocated to receive preoxygenation via facemask ventilation or high-flow nasal oxygenation. The ORI was measured and compared between both groups. RESULTS: The ORI increased during preoxygenation in all patients. At 1 min of preoxygenation, the ORI was significantly higher in the high-flow nasal oxygenation group (0.34 ± 0.33) than in the facemask ventilation group (0.21 ± 0.28; P = 0.003). The highest ORI was not significantly different between the two groups (0.68 ± 0.25 in the high-flow nasal oxygenation group vs. 0.70 ± 0.28 in the facemask ventilation group; P = 0.505). CONCLUSIONS: High-flow nasal oxygenation results in an oxygenation status similar to that provided by facemask ventilation during the induction process of general anaesthesia; therefore, high-flow nasal oxygenation is a feasible preoxygenation method. TRIAL REGISTRATION: Clinicaltrials.gov (NCT04291339).

A Novel Propofol Dosing Regimen for Pediatric Sedation during Radiologic Tests.

The dose of propofol for pediatric sedation during radiologic tests has been proposed as an equation of 0.75 + 0.14 × age (months) + 45.82 × body surface area (m2) based on results in a previous study. We compared this equation and the conventional dosing strategy for sedation in children undergoing radiologic tests. An amount of 180 children scheduled for magnetic resonance imaging (MRI) were randomized to experimental and control groups. The initial induction dose of propofol calculated using the equation was administered in the experimental group. In the control group, children received 1 mg/kg of the initial induction dose of propofol. Then, 0.5 mg/kg of the additional dose was followed to induce sedation in both groups. When awake or moving, a rescue injection of 0.5 mg/kg propofol was given. The total induction dose was more significant in the experimental group. The number of injections for induction in the experimental group was lesser. The dose and number of rescue injections in the experimental group were significantly less. The equation for the induction dose of propofol in a previous study could achieve quick induction of sedation and prevent a rescue injection during sedation. However, caution is needed when using the equation.

Comparison of the Effects of Lumbar Spine Flexion on the Acoustic Windows Between Young and Elderly Patients.

BACKGROUND: The effects of lumbar flexion on posterior longitudinal ligament (PLL) length as an acoustic window for neuraxial block in older patients have not been fully elucidated. OBJECTIVE: This study aimed to compare changes in PLL length during lumbar spine flexion in young and old patients. STUDY DESIGN: Observational cohort study. SETTING: Tertiary University Hospital. METHODS: Forty young and older adult patients were placed in the lateral decubitus position. To flex the lumbar spine, patients were asked to flex their hips and knees and then their neck and shoulder toward their knees as much as they could (fetal position). An assistant pushed the patients' abdomen to the back and held their neck and legs to help them maintain position. To obtain an optimal ultrasound view, lumbar spinal ultrasonography was performed from L5/S1 to L2/L3 using a paramedian oblique sagittal plane. PLL lengths were measured on the ultrasound image before fetal position, after unassisted fetal position, and after assisted fetal position. RESULTS: PLL lengths increased after lumbar spine flexion in both young and older adult  patients, except at the L3-L4 level in old patients. The change in PLL length during lumbar spine flexion was significantly lower in old patients than in young patients at the L5-S1 and L3-L4 levels (P = 0.0028 and P = 0.0134, respectively). After lumbar spine flexion, the PLL length was significantly different between the spinal levels in older patients (P = 0.0392). LIMITATIONS: First, we measured the PLL length as an acoustic window for neuraxial block using lumbar spinal ultrasonography. Second, the researcher who obtained the spinal ultrasound view was not blinded to the patient's group and position. However, the researcher who measured the PLL lengths on ultrasonography was blinded. Third, all participants had no history of surgery, trauma, or congenital abnormalities of the spine, regardless of age. CONCLUSION: Lumbar spine flexion can increase PLL length in young and old patients. However, lumbar spine flexion is less effective in increasing the PLL length in old patients than in young patients.

Effects of positive end-expiratory pressure on pulmonary atelectasis after paediatric laparoscopic surgery as assessed by ultrasound: A randomised controlled study.

INTRODUCTION: Positive end-expiratory pressure (PEEP) following alveolar recruitment manoeuvre (RM) can effectively prevent anaesthesia-induced atelectasis in children. We aimed to evaluate the individual effect of PEEP following RM on atelectasis at the end of laparoscopic surgery in infants and small children. METHODS: Children undergoing laparoscopic inguinal hernia repair aged 5 weeks to 2 years were randomly allocated to either the PEEP or control group. A progressive RM was performed after intubation in all cases. The PEEP group received PEEP of 5 cmH2O until the end of mechanical ventilation, while the control group did not receive any PEEP. Lung ultrasonography was performed to compare the number of atelectatic regions between the two groups after anaesthesia induction, after RM, and at the end of surgery in 12 thoracic regions. RESULTS: Overall, 432 ultrasonographic images were acquired from 36 children. At the end of surgery, the number of atelectatic regions (median [interquartile range]) was significantly lower in the PEEP group compared to the control group (2.0 [1.0-3.0] versus 4.0 [3.0-4.0] out of 12 regions, respectively; p = 0.02). While no difference was observed between the number of atelectatic regions after induction and at the end of surgery in the control group (p = 0.30), a decrease was observed in the PEEP group (3.0 [2.0-4.0] to 2.0 [1.0-3.0], respectively; p = 0.02). CONCLUSION: RM followed by a PEEP of 5 cmH2O can effectively reduce the regions of pulmonary atelectasis at the end of laparoscopic surgery in infants and small children.

The effect of oxygen concentration on atelectasis formation during induction of general anesthesia in children: A prospective randomized controlled trial.

BACKGROUND: In adults, the use of lower oxygen concentration during induction is associated with less atelectasis formation without an increase in incidence of hypoxia. However, it is unknown whether this remains true in the pediatric patients. METHODS: Fifty-four pediatric patients who were scheduled to undergo elective lower abdominal surgery were randomized to one of three oxygenation groups: 100%, 80%, or 60% oxygen (in air). During anesthesia induction, patients were ventilated with sevoflurane in 100%, 80%, or 60% oxygen. Endotracheal intubation and mechanical ventilation were performed. Atelectasis was diagnosed using LUS, which was performed after anesthetic induction and at the end of surgery. RESULTS: We assessed atelectasis after anesthetic induction and at the end of surgery. After anesthetic induction, the number of atelectatic lung regions was significantly different among the three groups (median [IQR], 2.0 [1.0-2.5], 2.0 [1.0-2.8], and 3.0 [2.0-3.0] in the 60%, 80%, and 100% oxygen groups, p = .033) and between the 60% and 100% groups (p = .015), but not between 80% and 100% groups (p = .074). However, no differences in the number of atelectatic lung regions were found among the three groups at the end of surgery (2.0 [1.3-3.8], 3.0 [1.8-3.0], and 4.0 [2.0-4.0] in the 60%, 80%, and 100% oxygen groups; p = .169). CONCLUSION: Lower oxygen concentration during anesthetic induction is associated with less atelectasis formation immediately after anesthetic induction in children. In addition, applying 80% oxygen instead of 100% oxygen is not enough to prevent atelectasis formation, and 60% oxygen should be applied to prevent atelectasis. However, this effect does not last until the end of surgery.

Effect of upper respiratory infection on anaesthesia induced atelectasis in paediatric patients.

Upper respiratory tract infection (URI) symptoms are known to increase perioperative respiratory adverse events (PRAEs) in children undergoing general anaesthesia. General anaesthesia per se also induces atelectasis, which may worsen with URIs and yield detrimental outcomes. However, the influence of URI symptoms on anaesthesia-induced atelectasis in children has not been investigated. This study aimed to demonstrate whether current URI symptoms induce aggravation of perioperative atelectasis in children. Overall, 270 children aged 6 months to 6 years undergoing surgery were prospectively recruited. URI severity was scored using a questionnaire and the degree of atelectasis was defined by sonographic findings showing juxtapleural consolidation and B-lines. The correlation between severity of URI and degree of atelectasis was analysed by multiple linear regression. Overall, 256 children were finally analysed. Most children had only one or two mild symptoms of URI, which were not associated with the atelectasis score across the entire cohort. However, PRAE occurrences showed significant correspondence with the URI severity (odds ratio 1.36, 95% confidence interval 1.10-1.67, p = 0.004). In conclusion, mild URI symptoms did not exacerbate anaesthesia-induced atelectasis, though the presence and severity of URI were correlated with PRAEs in children.Trial registration: Clinicaltrials.gov (NCT03355547).

Pediatric characteristics and the dose of propofol for sedation during radiological examinations: a retrospective analysis.

OBJECTIVE: The present study aimed to investigate patients' characteristics that can affect the dose of propofol required to sedate children undergoing imaging. METHODS: In this retrospective, observational study, we reviewed medical records of children aged 0 to 18 years who were classified as having American Society of Anesthesiologists status 1 or 2 and they underwent imaging under propofol sedation between January 2011 and August 2016. Collected data included patients' demographics, propofol doses, duration of sedation, and complications. Regression analysis was performed to determine patients' characteristics that may affect the dose of propofol required to induce sedation. RESULTS: A total of 925 patients were included. Simple linear regression showed that the dose of propofol was correlated with age, height, weight, and body surface area. Using the results of multiple linear regression, the following formula was used to estimate the dose of propofol (mg) for sedation: 0.75 + 0.14 × age (months) + 45.82 × body surface area (m2). CONCLUSION: A child's age, height, and body surface area should be considered when deciding the induction dose of propofol. Additionally, the formula that we have proposed can be used to estimate the dose of propofol required to induce sedation in children undergoing imaging.

A novel electromagnetic guidance ultrasound system on radial artery cannulation: a prospective randomized controlled trial.

BACKGROUND: Radial artery cannulation can cause complications such as haematoma formation or thrombosis due to its small diameter. Recently, a novel ultrasound device equipped with an electromagnetic guidance system was introduced, showing the path and alignment of the needle during the procedure. The aim of this study was to investigate the effects of this novel system on both success and complication rates during radial artery cannulation under ultrasound guidance. METHODS: In this randomized controlled trial, 76 adults scheduled for neurosurgery requiring radial artery cannulation were recruited. In group E (n = 38), radial artery cannulation was performed using the electromagnetic guidance ultrasound system, whereas in group C (n = 38), the procedure was performed using conventional ultrasound guidance. The success rates of cannulation on the first attempt, cannulation times, number of attempts, and incidence of complications were compared between the two groups. RESULTS: There was a significant difference in the success rates on the first attempt between the two groups (group C = 78.9% vs. group E = 94.7%, P = 0.042). Incidences of posterior wall puncture and haematoma formation (group C = 8 vs. group E = 1; P = 0.028) were significantly lower in group E than in group C. The median cannulation time for successful attempts was comparable between groups. CONCLUSIONS: Use of the novel electromagnetic guidance system resulted in a better success rate on the first attempt and a lower incidence of complications during radial artery cannulation. TRIAL REGISTRATION: This study was registered at http://cris.nih.go.kr (registration number: KCT0002476 ).

A Randomized Controlled Trial Comparing Novel Triple-Cuffed Double-Lumen Endobronchial Tubes with Conventional Double-Lumen Endobronchial Tubes for Lung Isolation.

Placing a double-lumen endobronchial tube (DLT) in an appropriate position to facilitate lung isolation is essential for thoracic procedures. The novel ANKOR DLT is a DLT developed with three cuffs with a newly added carinal cuff designed to prevent further advancement by being blocked by the carina when the cuff is inflated. In this prospective study, the direction and depth of initial placement of ANKOR DLT were compared with those of conventional DLT. Patients undergoing thoracic surgery (n = 190) with one-lung ventilation (OLV) were randomly allocated into either left-sided conventional DLT group (n = 95) or left-sided ANKOR DLT group (n = 95). The direction and depth of DLT position were compared via fiberoptic bronchoscopy (FOB) after endobronchial intubation between the groups. There was no significant difference in the number of right mainstem endobronchial intubations between the two groups (p = 0.468). The difference between the initial depth of DLT placement and the target depth confirmed by FOB was significantly lower in the ANKOR DLT group than in the conventional DLT group (1.8 ± 1.8 vs. 12.9 ± 9.7 mm; p < 0.001). In conclusion, the ANKOR DLT facilitated its initial positioning at the optimal depth compared to the conventional DLT.

Systemic Lidocaine Infusion for Post-Operative Analgesia in Children Undergoing Laparoscopic Inguinal Hernia Repair: A Randomized Double-Blind Controlled Trial.

Systemic lidocaine can provide satisfactory post-operative analgesia in adults. In this study, we assessed whether intravenous lidocaine is effective for post-operative analgesia and recovery in children undergoing laparoscopic inguinal hernia repair. A total of 66 children aged from six months to less than six years were classified in either the lidocaine (L) or control (C) groups. Children in Group L received a lidocaine infusion (a bolus dose of 1 mL kg-1, followed by a 1.5 mg kg-1 h-1 infusion), whereas Group C received the same volume of 0.9% saline. The primary outcome was the number of patients who presented face, legs, activity, crying and consolability (FLACC) scores of four or more, and therefore received rescue analgesia in the post-anesthesia recovery care unit (PACU). Secondary outcomes included the highest FLACC score in the PACU, FLACC, and the parents' postoperative pain measure (PPPM) score at 48 h post-operation, as well as side effects. The number of children who received rescue analgesia in the PACU was 15 (50%) in Group L and 22 (73%) in Group C (p = 0.063). However, the highest FLACC score in PACU was lower in Group L (3.8 ± 2.4) than in Group C (5.3 ± 2.7) (p = 0.029). In conclusion, systemic lidocaine did not reduce the number of children who received rescue analgesia in PACU.

Factors affecting determination of the optimal ketamine dose for pediatric sedation.

OBJECTIVE: Children are sedated before undergoing diagnostic imaging tests in emergency medicine or pediatric sedation anesthesia units. The aim of this study was to identify variables potentially affecting the dose of ketamine required for induction of sedation in pediatric patients undergoing diagnostic imaging. METHODS: This retrospective study included children aged 0 to 18 years who underwent sedation with ketamine for computed tomography or magnetic resonance imaging in the pediatric sedation anesthesia unit of a tertiary medical center between January 2011 and August 2016. The children's hemodynamic status and depth of sedation were monitored during the examination. We recorded data on demographics, categories of imaging tests, ketamine doses administered, adverse events, respiratory interventions, and duration of sedation. Data for patients who experienced adverse events were excluded. RESULTS: Sixty-six patients were included in the final analysis. Univariate linear regression analysis revealed that patient age, height, and body surface area (BSA) affected the sedative dose of ketamine administered. These three variables showed multicollinearity in multivariate linear regression analysis and were analyzed in three separate models. The model with the highest adjusted R-squared value suggested the following equation for determination of the dose of ketamine required to induce sedation: ketamine dose (mg)=-1.62+0.7×age (months)+36.36×BSA (m2). CONCLUSION: Variables such as age and BSA should be considered when estimating the dose of ketamine required for induction of sedation in pediatric patients.

Comparison of the acoustic windows for the thoracic paramedian epidural approach after shoulder rotation: The lateral decubitus versus the sitting position.

BACKGROUND: The aim of this study was to compare the mean lengths of the posterior longitudinal ligament (PLL) as the acoustic window during the thoracic paramedian epidural approach after shoulder rotation, while subjects were in the lateral decubitus or in the sitting position. METHODS: Thirty-two adult male volunteers were placed in the right decubitus position or sitting position on a horizontal operating table. To obtain an optimal ultrasound view for the PLL on the right side, thoracic spinal ultrasonography was performed at the T6/7 interspace using the paramedian oblique sagittal plane. PLL length was measured on the ultrasound image before and after right shoulder rotation. RESULTS: Before shoulder rotation, the difference in mean PLL length between the sitting (11.1±1.3mm) and lateral decubitus (10.7±1.2mm) positions was not statistically significant (P=0.05). Within-position, the before and after comparison revealed that after shoulder rotation, PLL length was significantly increased to 12.2±1.4mm (P<0.001) and 12.0±1.5mm (P<0.001) in the sitting and lateral decubitus positions, respectively. However, after shoulder rotation the between-position difference in mean PLL length was not statistically significant (P=0.50) CONCLUSIONS: Shoulder rotation did not result in a statistically significant difference in the dimension of the acoustic target window for paramedian thoracic epidural access in the sitting compared to the lateral decubitus position.

Safety and Efficacy of Off-label and Unlicensed Medicines in Children.

BACKGROUND: The aim of this study was to explore the use of off-label/unlicensed drugs to confirm the safety and efficacy of their prescription in children in Korea. METHODS: In this retrospective study, we analyzed data of patients who received any of the 32 drugs between January-December 2014 in tertiary hospitals in Korea, including demographics, diagnoses, reasons for the medication, administration route, and details of adverse drug reactions. Additionally, the mortality in the cohort was assessed. The primary outcomes were efficacy and safety, including mortality, of these drugs in pediatric patients. The secondary outcomes were the current statuses of the use of off-label/unlicensed drugs in two centers. RESULTS: Totally, 5,130 prescriptions were found in 2,779 patients. Age (73.5%) and indication (11.7%) were the most frequent reasons for prescriptions being off-labeled/unlicensed. Approximately 88% of the prescriptions were effective, and 19% of the patients developed adverse drug reactions. The number of prescriptions was significantly higher in children with adverse drug reactions than it was in those without (2.8 vs. 1.5; P < 0.001). The number of prescribed off-label/unlicensed medicines and age at prescription were independently associated with adverse drug events (odds ratio, 1.55 and 1.1; P < 0.001 and 0.034, respectively). CONCLUSION: Children are still prescribed medicines that are not authorized in terms of age, weight, indications, or routes of administration. Therefore, many old products require re-assessment of authorization. More prospective clinical studies should be performed to confirm the efficacy and safety of drugs in the pediatric population.

A comparison of the pharmacokinetic and pharmacodynamic properties of nitroglycerin according to the composition of the administration set: A preliminary study.

BACKGROUND: There is a risk of drug sorption into an intravenous administration set composed of polyvinyl chloride (PVC), polyurethane (PU), or polyolefin (PO). This has implications on the dose of the active ingredient the patient receives, and thus therapeutic success. This study aimed to determine the plasma concentration of nitroglycerin and the effect of nitroglycerin on patients based on the composition of the administration set. METHODS: Using a randomized, open-labeled, 3 × 3 crossover method, 9 volunteers were assigned to 3 groups. In period I, nitroglycerin (100 µg/mL) was infused via a PVC- (group A), PU- (group B), or PO-based (group C) administration set. In period II, PU- (group A), PO- (group B), and PVC-based (group C) administration sets were used, and in period III, PO- (group A), PVC- (group B), and PU-based (group C) administration sets were used. The rate of drug administration in all periods was 12 mL/hour for 30 minutes using an infusion pump. Blood samples were collected, and the plasma concentrations of nitroglycerin were analyzed using validated high-performance liquid chromatography coupled with tandem mass spectrometry. Blood pressure was determined using a sphygmomanometer applied to the other upper arm at an interval of 5 minutes. RESULTS: We observed that the mean plasma concentration of nitroglycerin over time when administered using a PO-based tube was higher than that when using a PU- or PVC-based tube. When the percent change of the mean arterial pressure from baseline at each time point was compared among groups, there were statistically significant differences between PU and PO or PVC at most points during nitroglycerin infusion. CONCLUSION: Our results showed higher nitroglycerin plasma concentration and lower arterial pressure when a PO-based administration set was used than when a PVC- or PU-based administration set was used. PO-based administration sets may be more appropriate for nitroglycerin administration compared to those composed of PVC or PU.

A Simulation Study of Propofol Effect-Site Concentration for Appropriate Sedation in Pediatric Patients Undergoing Brain MRI: Pharmacodynamic Analysis.

PURPOSE: We aimed to establish the propofol effect-site concentration (Ce) for appropriate sedation by pharmacodynamic analysis and to determine the propofol Ce during occurrence of sedation-related side effects in pediatric patients undergoing brain magnetic resonance imaging (MRI). MATERIALS AND METHODS: In 50 pediatric patients scheduled for brain MRI, sedation was induced with 2.0 mg/kg propofol; additional propofol doses were 0.5-1 mg/kg. Propofol Ce was simulated by inputting the propofol administration profiles of patients into a pediatric compartmental model (Choi model). The relationship between propofol Ce and probabilities of sedation and recovery were analyzed using a sigmoidal Emax model. The simulated propofol Ce for sedation-related side effects was investigated. Population model parameters were estimated using the Nonlinear Mixed-Effects Modelling software. RESULTS: The mean values of propofol Ce50 for sedation during the preparation, scanning, and recovery phases were 1.23, 0.43, and 0.39 µg/mL. The simulated propofol Ce values during oxygen desaturation (SpO2 <90%) (3 patients; 6%), hypotension (16 patients; 32%), and bradycardia (12 patients; 24%) were 3.01±0.04, 2.05±0.63, and 2.41±0.89 µg/mL, respectively. CONCLUSION: The required propofol Ce50 for applying monitors during the preparation phase before the start of MRI was higher than the propofol Ce50 required during the scanning phase. During low-intensity stimulation phases, such as scanning, propofol bolus dose should be strictly titrated not to exceed the propofol Ce that can lead to oxygen desaturation because of the relatively low propofol Ce (Ce95, 1.43 µg/mL) required for sedation in most patients.

Determination of the optimal depth of a left internal jugular venous catheter in infants: A prospective observational study.

BACKGROUND: Few reports exist regarding the optimal depth of a left-sided central venous catheter in pediatric patients. We aimed to provide a guideline for the optimal depth of central venous catheters at the left internal jugular vein in infants, using anatomical landmarks, age, height, and weight. METHODS: A two-stage study was conducted. In the first observational study, infants aged ≤1 year and scheduled for elective surgery requiring a central venous catheter were enrolled. The tip of the central venous catheter was confirmed using transthoracic echocardiography. Linear regression modeling was performed to determine the association between the insertion depth of the central venous catheter and the I-A-B distance (I, the insertion point; A, the sternal head of the left clavicle; B, the midpoint of the perpendicular line drawn between the sternal head of the right clavicle and an imaginary line between the nipples), based on age, height, and weight. In the second study, the results of the first study were validated in another group of consecutive infants. RESULTS: In the first study, the data of 67 patients were analyzed. The infant's height and I-A-B distance were highly correlated with the level of the central venous catheter tip (R2 =0.763 and 0.772, respectively; all P < .01), using the regression equations 0.11 ×  height (cm) + 0.19 and 1.02 ×  I-A-B (cm) + 1.55, respectively. In the second study, height was also highly correlated with the insertion depth of the central venous catheter in another 42 infants (r = .938, P = <.001). In a Bland-Altman's analysis, the mean bias and precision of the actual insertion depth and predicted depth using height were 0.09 and 0.15 cm, respectively. The limits of agreement were -0.19 and 0.38 cm, respectively. CONCLUSION: In infants, the optimal depth of a central venous catheter at the left internal jugular vein can be determined with a simple formula using height.

Evaluation of tacrolimus sorption to PVC- and non-PVC-based tubes in administration sets: Pump method vs. drip method.

Tacrolimus sorption to tubes was evaluated using pump and drip methods For tubes, polyvinylchloride (PVC)- and non-PVC-based (polyurethane [PU] and polyolefin [PO]) tubes were used. First, inner surface properties of tubes were analyzed using field emission scanning electron microscopy and X-ray photoelectron spectroscopy. Tacrolimus was quantitatively analyzed using high-performance liquid chromatography with UV detection. For kinetic sorption analysis, diluted tacrolimus to 10µg/mL was passed through 1-m-long tubes at 10mL/h. Samples were collected at 1-4h. The inner surface of PO-based tubes was relatively smooth and soft compared with those of PVC- and PU-based tubes. Atomic compositions of tubes matched chemical formulas of polymers excluding low-level impurity in PVC-based tubes. Tacrolimus was successfully analyzed and linearly determined at 2.5-20µg/mL. From both methods, PVC- and PO-based tubes exhibited the highest and the lowest (<10%) sorption levels to tacrolimus, respectively. Tacrolimus was stably delivered using the pump method. Results suggested that the pump method can estimate tacrolimus sorption in administration set tubes and evaluate other sorptional drugs used at low concentrations. PO-based tubes also have promising potential as an alternative for administration set tubes.

Evaluation of Drug Sorption to PVC- and Non-PVC-based Tubes in Administration Sets Using a Pump.

Administration sets are delivery tools for the direct application of drugs into the body and are composed of a spike, a drip chamber, tubes, Luer adapters (connectors), a needle cover for protection, and other accessories. Drug sorption to tubes of administration sets is a critical issue in terms of safety and efficacy. Although drug sorption is an important factor in the quality of an administration set, there are no standard evaluation methods for the regulation of drug sorption to the tubes. Here, we describe an evaluation protocol for drug sorption to tubes of administration sets. Tubes made of polyvinyl chloride (PVC)- and non-PVC-based polymeric materials were cut to 1 m in length. Diazepam and tacrolimus were used as model drugs. In the kinetic sorption study, we selected the drug concentration and flow rate based on the clinical usage of these drugs. After the dilution of each drug in a glass bottle, the diluted drug solution was delivered through tubes of administration sets using a pump. Samples were collected in amber vials at appropriate time points and the drugs were analyzed using high-performance liquid chromatography. Drug concentrations and sorption levels to tubes of the administration sets were calculated. Acceptable criteria to ensure the quality of administration sets are recommended.

Measuring the depth of the caudal epidural space to prevent dural sac puncture during caudal block in children.

BACKGROUND: Caudal blocks are performed through the sacral hiatus in order to provide pain control in children undergoing lower abdominal surgery. During the block, it is important to avoid advancing the needle beyond the sacrococcygeal ligament too much to prevent unintended dural puncture. This study used demographic data to establish simple guidelines for predicting a safe needle depth in the caudal epidural space in children. METHODS: A total of 141 children under 12 years old who had undergone lumbar-sacral magnetic resonance imaging were included. The T2 sagittal image that provided the best view of the sacrococcygeal membrane and the dural sac was chosen. We used Picture Achieving and Communication System (Centricity® PACS, GE Healthcare Co.) to measure the distance between the sacrococcygeal ligament and the dural sac, the length of the sacrococcygeal ligament, and the maximum depth of the caudal space. RESULTS: There were strong correlations between age, weight, height, and BSA, and the distance between the sacrococcygeal ligament and dural sac, as well as the length of the sacrococcygeal ligament. Based on these findings, a simple formula to calculate the distance between the sacrococcygeal ligament and dural sac was developed: 25 × BSA (mm). CONCLUSION: This simple formula can accurately calculate the safe depth of the caudal epidural space to prevent unintended dural puncture during caudal block in children. However, further clinical studies based on this formula are needed to substantiate its utility.

Dexmedetomidine Inhibits Phenylephrine-induced Contractions via Alpha-1 Adrenoceptor Blockade and Nitric Oxide Release in Isolated Rat Aortae.

The goal of this in vitro study was to examine the effect of the alpha-2 adrenoceptor agonist dexmedetomidine on phenylephrine (alpha-1 adrenoceptor agonist)-induced contraction in isolated rat aortae and to elucidate the associated cellular mechanisms, with a particular focus on alpha-1 adrenoceptor antagonism. Dexmedetomidine dose-response curves were generated in isolated endothelium-intact and endothelium-denuded rat aortae precontracted with phenylephrine or 5-hydroxytryptamine. Endothelium-denuded aortic rings were pretreated with either dexmedetomidine or the reversible alpha-1 adrenoceptor antagonist phentolamine, followed by post-treatment with the irreversible alpha-1 adrenoceptor blocker phenoxybenzamine. Control rings were treated with phenoxybenzamine alone. All rings were repeatedly washed with Krebs solution to remove all pretreatment drugs, including phenoxybenzamine, phentolamine and dexmedetomidine. Phenylephrine dose-response curves were then generated. The effect of rauwolscine on the dexmedetomidine-mediated change in phenylephrine-induced endothelial nitric oxide synthase (eNOS) phosphorylation in human umbilical vein endothelial cells was examined using western blotting. The magnitude of the dexmedetomidine-mediated inhibition of phenylephrine-induced contraction was higher in endothelium-intact aortae than in endothelium-denuded aortae or endothelium-intact aortae treated with Nω-nitro-L-arginine methyl ester. However, dexmedetomidine did not significantly alter 5-hydroxytryptamine-induced contraction. In further experiments, prazosin attenuated dexmedetomidine-induced contraction. Additionally, pretreatment with either dexmedetomidine plus phenoxybenzamine or phentolamine plus phenoxybenzamine produced greater phenylephrine-induced contraction than phenoxybenzamine alone, suggesting that dexmedetomidine protects aortae from the alpha-1 adrenoceptor blockade induced by phenoxybenzamine. Rauwolscine attenuated the dexmedetomidine-mediated enhancement of phenylephrine-induced eNOS phosphorylation. Taken together, these results suggest that dexmedetomidine attenuates phenylephrine-induced contractions via alpha-1 adrenoceptor blockade and endothelial nitric oxide release in the isolated rat aorta.