Multimodal blood loss prevention bundle for endoscopic resection of juvenile nasopharyngeal angiofibroma: A case series.

Surgery for excision of juvenile nasopharyngeal angiofibroma (JNA) carries the possibility of massive life-threatening haemorrhage. Anaesthetic management aims to maintain haemodynamic stability and reduce blood loss. This case series describes the application of the bundled approach as a multimodal blood loss prevention bundle (MBLPB). Twenty patients underwent 23 surgeries with MBLPB. The blood loss and the number of units of blood transfused were recorded. The surgeon satisfaction score was assessed. The median [interquartile range (IQR)] estimated blood loss was 1300 (650-2350) ml. Patients with tumours in stages I and II had a median (IQR) blood loss of 550 (270-750) ml compared to patients with higher grades of tumours (stages III, IV) with a median (IQR) blood loss of 2100 (1300-2500) ml. Median (IQR) units of packed red cells transfused was 1 (0-3). The surgeon's satisfaction score was high when MBLPB was applied for JNA. However, it does not appear to reduce blood loss markedly.

Advances in the Clinical Application of Trendelenburg Position.

The Trendelenburg position and reverse Trendelenburg position are frequently employed during lower abdominal surgery to achieve optimal surgical field visualization and complete exposure of the operative site, particularly under pneumoperitoneum conditions. However, these positions can have significant impacts on the patient's physiological functions. This article overviews the historical background of Trendelenburg position and reverse Trendelenbury position, their effects on various physiological functions, recent advancements in their clinical applications, and strategies for preventing and managing associated complications.

Advances in the Clinical Application of Trendelenburg Position / 中国医学科学杂志(英文版)

The Trendelenburg position and reverse Trendelenburg position are frequently employed during lower abdominal surgery to achieve optimal surgical field visualization and complete exposure of the operative site, particularly under pneumoperitoneum conditions. However, these positions can have significant impacts on the patient's physiological functions. This article overviews the historical background of Trendelenburg position and reverse Trendelenbury position, their effects on various physiological functions, recent advancements in their clinical applications, and strategies for preventing and managing associated complications.

Reverse Trendelenburg Lithotomy with Certain Inclination Angles Reduces Stone Retropulsion during Ureteroscopic Lithotripsy for Proximal Ureteral Stone.

The objective of this study is to investigate how different inclination angles of reverse Trendelenburg lithotomy affect stone retropulsion and stone-free rates during ureteroscopic lithotripsy for proximal ureteral stones. Patients with proximal ureteral stones undergoing ureteroscopic lithotripsy in our institution between January 2019 and December 2020 were included according to predefined criteria. The rigid ureteroscope and Holmium: YAG laser were utilized to perform lithotripsy, and a stone basket was used to keep the stone in place and to avoid retropulsion. Before initiating lithotripsy, the upper part of the patient's body was tilted up to establish a reverse Trendelenburg posture with appropriate inclination angles. To quantify the stone-free rate, computed tomography was used to evaluate the residual stones in the kidney one month following surgery. Patients' clinical data were obtained retrospectively, including age, gender, the largest diameter of stone, stone density on computed tomography, and the distance between stone and ureteral pelvic junction, etc. Patients were divided into four groups based on the inclination angles of reverse Trendelenburg lithotomy: 0°, 10°, 20°, and 30°. The chi-square test was used to compare stone retropulsion and stone-free rates between groups. To discover possible determinants of the stone-free rate, logistic regression analyses were used. There were 189 patients that qualified. There were no differences in clinical characteristics between groups (p > 0.05). Multiple comparisons between groups revealed that the 20° and 30° groups had less retropulsion and a greater stone-free rate than the 0° and 10° groups (p < 0.05), whereas there were no significant differences in stone retropulsion or stone-free rates between the 20° and 30° groups or between the 0° and 10° groups (p > 0.05). The inclination angles as well as distance between the stone and ureteral pelvic junction were identified by using logistic regression analyses as the related factors for the stone-free rate. According to our results, the appropriate inclination angles of reverse Trendelenburg lithotomy during ureteroscopic lithotripsy for proximal ureteral stones would help preclude stone retropulsion and increase the stone-free rate.

The effects of 5-degree, 10-degree and 20-degree reverse Trendelenburg positions on intraoperative bleeding and postoperative Edemea and ecchymosis around the eye in open rhinoplasty.

PURPOSE: In this study, we investigated the effect of reverse Trendelenburg position (RTP), with five, ten, and twenty degrees, on intraoperative bleeding and postoperative edema and ecchymosis around the eye in open rhinoplasty operations. MATERIALS AND METHODS: Ninety patients undergoing open rhinoplasty were divided into three groups, 5° angle RTP (Group 5; n = 30), 10° angle RTP (Group 10; n = 30), and 20° angle RTP (Group 20; n = 30). After 3 min of preoxygenation, anesthesia was induced with 3 mg.kg-1 propofol, 1 µg.kg-1 fentanyl, and 0.6 mg/kg rocuronium for muscle relaxation. Maintenance of anesthesia was provided with a minimum alveolar concentration of 1-1.5 with sevoflurane, 1:1 O2/N2O. Hemodynamic variables, intraoperational bleeding, postoperative 1st, 3rd and 7th days ecchymosis and edema around the eyes of the patients were compared between the groups. RESULTS: Edema changes on postoperative 1st, 3rd and 7th days and ecchymosis changes around the eyes on postoperative 1st and 3rd days in Group 20 were found significantly lower than Group 5 (p < 0.017). Besides, the change of ecchymosis on the postoperative 1st day was found significantly lower in Group 20 compared to Group 10 (p < 0.017). The amount of intraoperative bleeding and surgical field evaluation score were found to be significantly lower in Group 10 and Group 20 compared to Group 5 (p < 0.017). CONCLUSION: We concluded that in open rhinoplasty surgeries, 20° degree RTP reduces intraoperative blood loss and provides a more bloodless surgical field, as well as reducing edema and ecchymoses around the eyes in the postoperative period.

Successive perioperative management of laparoscopic liver resection in the reverse Trendelenburg position for a patient with Fontan physiology: a case report.

BACKGROUND: Laparoscopic surgery for a patient with Fontan physiology is challenging because pneumoperitoneum and positive pressure ventilation could decrease venous return and the accumulated partial pressure of arterial carbon dioxide (PaCO2) could increase pulmonary vascular resistance, which might lead to disruption of the hemodynamics. CASE PRESENTATION: A 25-year-old man with Fontan physiology was scheduled to undergo laparoscopic liver resection for Fontan-associated liver disease (FALD) with noninvasive monitoring of cardiac output (CO) by transpulmonary thermodilution in addition to transesophageal echocardiography. The abdominal air pressure was maintained low, and we planned to switch to open abdominal surgery promptly if hemodynamic instability became apparent because of the accumulated PaCO2 or postural change. Consequently, the pneumoperitoneum had limited influence on circulatory dynamics, but central venous pressure significantly decreased with postural change to the reverse Trendelenburg position. Laparoscopic liver resection for FALD was performed successfully with no significant changes in CO and central venous saturation. CONCLUSIONS: With strict circulation management, laparoscopic surgery for a patient with Fontan physiology can be performed safely. Comprehensive hemodynamic assessment by noninvasive transpulmonary thermodilution can provide valuable information to determine the time for shift to open abdominal surgery.

Optimum Degree of Head Elevation/Reverse Trendelenburg Position for Sinus Surgery: Systematic Review.

BACKGROUND: This review aims to evaluate the effect of Reverse Trendelenburg Position (RTP) on bleeding and Boezaart score and to determine the optimum degree of head elevation through a systematic review and meta-analysis.Methodology: We conducted a systematic review according to PRISMA guidelines and a literature search was performed on PubMed, Web of Science, Cochrane, Dental and Oral Science, Google scholar and Clinicaltrials.gov and included randomized controlled trials (RCTs) in English language only. We extracted all relevant data and conducted quality assessment using Cochrane risk of Bias tool (Version 2). We also performed quality assessment of the outcomes using GRADE. Meta-analysis for all the outcomes using conducted on RevMan version 5.3. RESULTS: The search identified 629 articles and three RCTs that met our inclusion criteria. Two were included in the meta-analysis. A total of 124 patients were assessed for bleeding during sinus surgery and there was a significant reduction in total blood loss in RTP (10-15°) when compared to horizontal position by 134 ml (Mean Difference (MD): -134.23; 95% confidence interval (CI): -184.13 to -67.27). RTP also had a significant reduction in bleeding per minute by 1.07 ml/min (MD: -1.07; 95%CI: (-1.69 to -0.44), while the Boezaart score was significantly lower in the RTP group (MD: -0.69; 95%CI: -0.94 to -0.43) when compared to horizontal position. CONCLUSION: Though with limited evidence RTP for ESS reduces total blood loss, blood loss per minute and improves visualization. Further studies are needed to assess the actual impact and optimal degree of head elevation.

The 15° reverse Trendelenburg position can improve visualization without impacting cerebral oxygenation in endoscopic sinus surgery-A prospective, randomized study.

BACKGROUND: In this study we compared intraoperative bleeding and regional cerebral oxygenation in patients with different degrees of the reverse Trendelenburg position (RTP) during endoscopic sinus surgery (ESS). METHODS: In total, 120 patients with chronic rhinosinusitis treated by ESS were randomly assigned to the following 4 groups: a horizontal position (HP) group, and 5°, 10°, and 15° RTP (5-RTP, 10-RTP, and 15-RTP, respectively) groups. The primary outcome was the Boezaart grading scale (BS). The cerebral oxygen saturation (ScO2 ), total blood loss, numerical rating scale (NRS) scores, and complications were also recorded. RESULTS: The median BS values in the HP, 5-RTP, 10-RTP, and 15-RTP groups were 2.0, 2.0, 2.1, and 1.7, respectively. Multiple pairwise comparisons of the BS showed significant differences between the 15-RTP group and the other 3 groups (HP, 5-RTP, and 10-RTP). Regarding the NRS and bleeding rate, significant differences were found between the HP and 15-RTP groups. No difference was found in ScO2 among the 4 groups, and no cerebral desaturation events occurred in any group. No complications, including vital organ (heart, brain, and kidney) dysfunction problems, were reported in this study during hospitalization. CONCLUSION: Compared with HP, 5-RTP, and 10-RTP, 15-RTP can improve visual clarity during ESS, and ScO2 is not affected by the degree of RTP. No cerebral deoxygenation or vital organ dysfunction was observed in this study. Therefore, we recommend 15-RTP with moderate deliberate hypotension for ESS.

Reverse Trendelenburg position applied prior to pneumoperitoneum prevents excessive increase in optic nerve sheath diameter in laparoscopic cholecystectomy: randomized controlled trial.

The aim of this randomized controlled trial was to determine whether applying the reverse Trendelenburg position before pneumoperitoneum has a preventive effect on increased intracranial pressure using optic nerve sheath diameter (ONSD) measurement as a noninvasive parameter. Seventy-nine patients were allocated to two groups according to whether pneumoperitoneum was applied in the supine position (group S, n = 40) or in the reverse Trendelenburg position (group RT, n = 39). The ONSD was measured at the following time points: T0: before anesthesia; T1: after endotracheal intubation; T2: after pneumoperitoneum in group S and after positioning in group RT; T3: after positioning in group S and after pneumoperitoneum in group RT; T4: 30 min after endotracheal intubation, and T5: after desufflation. The end-tidal carbon dioxide (EtCO2), regional cerebral oxygen saturation (rSO2), peripheral oxygen saturation (SpO2), mean arterial pressure (MAP), heart rate (HR), peak inspiratory pressure (Ppeak), and dynamic compliance (Cdyn) were recorded. Background and perioperative characteristics were similar in both groups. In group S, the ONSD was higher at T2, T3, T4, and T5 than that in group RT (p < 0.001, p = 0.002, p = 0.001, and p = 0.012, respectively). In the same group, the number of patients with an ONSD above 5.8 mm was higher at T2, T3, and T4 (p < 0.001, p = 0.042, p = 0.036, respectively). The rSO2 and SpO2 were not different between the groups. The mean arterial pressure was lower in group RT at T2, and the HR was not different between the groups (p < 0.001). In group S, Ppeak was higher and Cdyn was lower at T2 (p < 0.001). The number of patients with nausea was higher in group S (p = 0.027). The present study demonstrates that applying the reverse Trendelenburg position before pneumoperitoneum prevented an increase in the ONSD in patients undergoing laparoscopic cholecystectomy.Trial registration The trial was registered prior to patient enrollment at https://register.clinicaltrials.gov (NCT04224532, Date of the registration: January 8, 2020).

A patient with post-Fontan operation underwent left hepatectomy and caudate lobectomy for hepatocellular carcinoma: a case report.

BACKGROUND: The Fontan procedure has been widely accepted for children with single ventricle physiology and guarantees survival rates of approximately 80% at age 20 years. However, there have been cases of Fontan-associated liver disease (FALD) caused due to congestion, along with recent reports of the development of hepatocellular carcinoma (HCC) in younger patients with FALD. The literature consists of only five previous case reports of patients who underwent hepatectomy for HCC due to poorer cardiac function and liver cirrhosis caused due to congestion. CASE PRESENTATION: The patient was a 37-year-old woman who presented with epigastralgia. Computed tomography (CT) revealed a liver tumor, 8 cm in diameter, in the caudate lobe. Liver damage was A, with an indocyanine green retention rate of 6% at 15 min. The levels of alpha-fetoprotein (AFP) and protein induced by vitamin K antagonists-II (PIVKA-II) were elevated to 81,663 ng/ml (normal < 10 ng/ml) and 238 mAU/ml (normal < 40 mAU/ml), respectively. Left ventricular ejection fraction was 56%, and central venous pressure (CVP) was 12 mmHg. Left hepatectomy and caudate lobe resection were successfully performed in the reverse Trendelenburg position which reduced the CVP. The total operation duration was 450 min, with a total blood loss of 3200 ml. The patient's postoperative course was uneventful, and she is still alive 16 months after surgery. CONCLUSIONS: First left hepatectomy with caudate lobectomy during reverse Trendelenburg position which reduced the CVP was performed in a patient with HCC and FALD.

Stroke Volume Variation and Stroke Volume Index Can Predict Fluid Responsiveness after Mini-Volume Challenge Test in Patients Undergoing Laparoscopic Cholecystectomy.

Background and Objectives: For using appropriate goal-directed fluid therapy during the surgical conditions of pneumoperitoneum in the reverse Trendelenburg position, we investigated the predictability of various hemodynamic parameters for fluid responsiveness by using a mini-volume challenge test. Materials and Methods: 42 adult patients scheduled for laparoscopic cholecystectomy were enrolled. After general anesthesia was induced, CO2 pneumoperitoneum was applied and the patient was placed in the reverse Trendelenburg position. The mini-volume challenge test was carried out with crystalloid 4 mL/kg over 10 min. Hemodynamic parameters, including stroke volume variation (SVV), cardiac index (CI), stroke volume index (SVI), mean arterial pressure (MAP), and heart rate (HR), were measured before and after the mini-volume challenge test. The positive fluid responsiveness was defined as an increase in stroke volume index ≥10% after the mini-volume challenge. For statistical analysis, a Shapiro-Wilk test was used to test the normality of the data. Continuous variables were compared using an unpaired t-test or the Mann-Whitney rank-sum test. Categorical data were compared using the chi-square test. A receiver operating characteristic curve analysis was used to assess the predictability of fluid responsiveness after the mini-volume challenge. Results: 31 patients were fluid responders. Compared with the MAP and HR, the SVV, CI, and SVI showed good predictability for fluid responsiveness after the mini-volume challenge test (area under the curve was 0.900, 0.833, and 0.909, respectively; all p-values were <0.0001). Conclusions: SVV and SVI effectively predicted fluid responsiveness after the mini-volume challenge test in patients placed under pneumoperitoneum and in the reverse Trendelenburg position.

Positioning of a morbidly obese patient during retinal surgery.

A body mass index (BMI) ≥35 kg/m2 is classified as obese, and a BMI ≥40 kg/m2 is classified as morbidly obese. Obese people are at a higher risk for developing cardiovascular complications like ischemic heart diseases, congestive cardiac failure, hypertension, type 2 diabetes mellitus and obstructive sleep apnea (OSA) among other health issues. Central obesity can also increase the pleural pressure and cardiac filling pressures, thus increasing the intracranial (ICP) and intraocular pressure (IOP). These clinical co-morbidities can make retina surgeries, which require patient in supine position for 45-90 minutes, a challenging task. We present our experience in the intraoperative positioning of such a patient who underwent surgery for retinal detachment.

The Effect of Patient Positioning on Amount of Intraoperative Bleeding in Rhinoplasty: A Randomized Controlled Trial.

BACKGROUND: There is a rich blood flow to the mucosa in the nasal region. In rhinoplasty, surgical procedures are performed in a narrow and confined space. So bleeding during surgery reduces visibility which can complicate the procedure. This study investigated the effects of the patient position on amount of intraoperative bleeding during surgical procedures. PATIENTS AND METHODS: This randomized controlled trial was conducted on 71 patients who underwent elective rhinoplasty. The patients were operated on in three groups. Group 1 consisted of 23 patients who were operated on in the supine position; Group 2 included 28 patients who were operated on using a 15° angle reverse Trendelenburg position; Group 3 consisted of 20 patients who were operated on at a 20° angle reverse Trendelenburg position. RESULTS: There were statistically significant differences between the groups in regard to surgeon satisfaction and the amount of intraoperative bleeding. The amount of intraoperative bleeding in Group 1 was significantly higher than those of Groups 2 and 3, and surgeon satisfaction was lower. CONCLUSIONS: Reverse Trendelenburg position reduces intraoperative bleeding in rhinoplasty patients while facilitating the procedure compared to the supine position. Surgery at a 15° angle reverse Trendelenburg position provides the optimum working conditions by both significantly reducing intraoperative bleeding and allowing for comfortable conditions for the surgeon. LEVEL OF EVIDENCE I: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Reverse trendelenburg position can alleviate postoperative nausea and vomiting in thyroid surgery: from Logistic multivariate analysis / 中华内分泌外科杂志

Objective To assess the clinical significance of reverse trendelenburg position in preventing postoperative nausea and vomiting(PONV)in thyroid surgery.Methods 110 patients with papillary thyroid carcinoma(PTC) admitted from Feb.2013 to Mar.2014 were prospectively divided into experimental group and the control group according to whether reserve trendelenburg position was adopted.Univariate and multivariate method were used to analyze relations between PONV and surgical position,gender,age,body mass index,hypertension,surgical time,ASA classification,anesthesia,and motion sickness.Results Of the 110 cases of PTC,the incidence of PONV was 16.28％ (7/43) in the experimental group while it was 37.31％ (25/67) in the control group.The difference had statistical significance(P ＜ 0.05).Statistical analysis showed that PONV was related to patients'gender,surgical position,surgical time,and motion sickness,while only surgical position and motion sickness was the independent risk factors.Conclusion Reverse trendelenburg position surgery can help to prevent PONV and promote recovery.

The correlation between the Trendelenburg position and the stroke volume variation.

BACKGROUND: The stroke volume variation (SVV), based on lung-heart interaction during mechanical ventilation, is a useful dynamic parameter for fluid responsiveness. However, it is affected by many factors. The aim of this study was to evaluate the effects of SVV on Trendelenburg (T) and reverse Trendelenburg (RT) position and to further elaborate on the patterns of the SVV with position. METHODS: Forty-two patients undergoing elective surgery were enrolled in this study. Fifteen minutes after standardized induction of anesthesia with propofol, fentanyl, and rocuronium with volume controlled ventilation (tidal volume of 8 ml/kg of ideal body weight, inspiration : expiration ratio of 1 : 2, and respiratory rate of 10-13 breaths/min), the patients underwent posture changes as follows: supine, T position at slopes of operating table of -5°, -10°, and -15°, and RT position at slopes of operating table of 5°, 10°, and 15°. At each point, SVV, cardiac output (CO), peak airway pressure (PAP), mean blood pressure, and heart rate (HR) were recorded. RESULTS: The SVV was significant decreased with decreased slopes of operating table in T position, and increased with increased slopes of operating table in RT position (P = 0.000). Schematically, it was increased by 1% when the slope of operating table was increased by 5°. But, the CO and PAP were significant increased with decreased slopes of operating table in T position, and decreased with increased slopes of operating table in RT position (P = 0.045, 0.027). CONCLUSIONS: SVV is subjected to the posture, and we should take these findings into account on reading SVV for fluid therapy.

The correlation between the Trendelenburg position and the stroke volume variation / 대한마취과학회지

BACKGROUND: The stroke volume variation (SVV), based on lung-heart interaction during mechanical ventilation, is a useful dynamic parameter for fluid responsiveness. However, it is affected by many factors. The aim of this study was to evaluate the effects of SVV on Trendelenburg (T) and reverse Trendelenburg (RT) position and to further elaborate on the patterns of the SVV with position. METHODS: Forty-two patients undergoing elective surgery were enrolled in this study. Fifteen minutes after standardized induction of anesthesia with propofol, fentanyl, and rocuronium with volume controlled ventilation (tidal volume of 8 ml/kg of ideal body weight, inspiration : expiration ratio of 1 : 2, and respiratory rate of 10-13 breaths/min), the patients underwent posture changes as follows: supine, T position at slopes of operating table of -5degrees, -10degrees, and -15degrees, and RT position at slopes of operating table of 5degrees, 10degrees, and 15degrees. At each point, SVV, cardiac output (CO), peak airway pressure (PAP), mean blood pressure, and heart rate (HR) were recorded. RESULTS: The SVV was significant decreased with decreased slopes of operating table in T position, and increased with increased slopes of operating table in RT position (P = 0.000). Schematically, it was increased by 1% when the slope of operating table was increased by 5degrees. But, the CO and PAP were significant increased with decreased slopes of operating table in T position, and decreased with increased slopes of operating table in RT position (P = 0.045, 0.027). CONCLUSIONS: SVV is subjected to the posture, and we should take these findings into account on reading SVV for fluid therapy.

Postural Intraocular Pressure Change at Trendelenberg Position Measured by Rebound Tonometer

PURPOSE: This study was carried out to evaluate the postural intraocular pressure (IOP) change in Trendelenburg, reverse Trendelenburg, and supine positions in healthy young males. METHODS: We measured the IOP values of 5 healthy young male volunteers (10 eyes) using an Icare PRO rebound tonometer in sitting, Trendelenburg, reverse Trendelenburg, and supine positions. RESULTS: The mean IOP in the supine position (18.63 mm Hg) was significantly higher (p < 0.01) than in the sitting position (15.31 mm Hg). When maintaining the Trendelenburg position, IOP gradually increased. CONCLUSIONS: In our study, the Trendelenburg position significantly increased the IOP compared to that in the supine position. The effects of increased IOP should be considered in situations that require Trendelenburg positioning, such as exercise or surgery.

The effects of hip abduction with external rotation and reverse Trendelenburg position on the size of the femoral vein; ultrasonographic investigation.

BACKGROUND: Femoral vein (FV) catheterization is required for critically ill patients, patients with difficult peripheral intravenous access, and patients undergoing major surgery. The purpose of this study was to evaluate the effects of hip abduction with external rotation (frog-leg position), and the frog-leg position during the reverse Trendelenburg position on diameter, cross-sectional area (CSA), exposed width and ratio of the FV using ultrasound investigation. METHODS: Ultrasonographic FV images of 50 adult subjects were obtained: 1) in the neutral position (N position); 2) in the frog-leg position (F position); 3) in the F position during the reverse Trendelenburg position (FRT position). Diameter, CSA, and exposed width of the FV were measured. Exposed ratio of the FV was calculated. RESULTS: The F and FRT positions increased diameter, CSA and exposed width of the FV significantly compared with the N position. However, the F and FRT positions had no significant effect on exposed ratio of the FV compared with the N position. The FRT position was more effective than the F position in increasing FV size. CONCLUSIONS: The F and FRT positions can be used to increase FV size during catheterization. These positions may increase success rate and reduce complication rate and, therefore, can be useful for patients with difficult central venous access or at high-risk of catheter-related complication.

The effects of hip abduction with external rotation and reverse Trendelenburg position on the size of the femoral vein; ultrasonographic investigation / 대한마취과학회지

BACKGROUND: Femoral vein (FV) catheterization is required for critically ill patients, patients with difficult peripheral intravenous access, and patients undergoing major surgery. The purpose of this study was to evaluate the effects of hip abduction with external rotation (frog-leg position), and the frog-leg position during the reverse Trendelenburg position on diameter, cross-sectional area (CSA), exposed width and ratio of the FV using ultrasound investigation. METHODS: Ultrasonographic FV images of 50 adult subjects were obtained: 1) in the neutral position (N position); 2) in the frog-leg position (F position); 3) in the F position during the reverse Trendelenburg position (FRT position). Diameter, CSA, and exposed width of the FV were measured. Exposed ratio of the FV was calculated. RESULTS: The F and FRT positions increased diameter, CSA and exposed width of the FV significantly compared with the N position. However, the F and FRT positions had no significant effect on exposed ratio of the FV compared with the N position. The FRT position was more effective than the F position in increasing FV size. CONCLUSIONS: The F and FRT positions can be used to increase FV size during catheterization. These positions may increase success rate and reduce complication rate and, therefore, can be useful for patients with difficult central venous access or at high-risk of catheter-related complication.