Prone vs supine percutaneous nephrolithotomy: does position affect renal pelvic pressures?

The purpose of this study was to measure and compare renal pelvic pressure (RPP) between prone and supine percutaneous nephrolithotomy (PCNL) in a benchtop model. Six identical silicone kidney models were placed into anatomically correct prone or supine torsos constructed from patient CT scans in the corresponding positions. A 30-Fr renal access sheath was placed in either the upper, middle, or lower pole calyx for both prone and supine positions. Two 9-mm BegoStones were placed in the respective calyx and RPPs were measured at baseline, irrigating with a rigid nephroscope, and irrigating with a flexible nephroscope. Five trials were conducted for each access in both prone and supine positions. The average baseline RPP in the prone position was significantly higher than the supine position (9.1 vs 2.7 mmHg; p < 0.001). Similarly, the average RPP in prone was significantly higher than supine when using both the rigid and flexible nephroscopes. When comparing RPPs for upper, middle, and lower pole access sites, there was no significant difference in pressures in either prone or supine positions (p > 0.05 for all). Overall, when combining all pressures at baseline and with irrigation, with all access sites and types of scopes, the mean RPP was significantly higher in the prone position compared to the supine position (14.0 vs 3.2 mmHg; p < 0.001). RPPs were significantly higher in the prone position compared to the supine position in all conditions tested. These differences in RPPs between prone and supine PCNL could in part explain the different clinical outcomes, including postoperative fever and stone-free rates.

Flank versus prone position in percutaneous nephrolithotomy: a meta-analysis of randomized controlled studies.

The objective of this study is to assess the safety and efficacy of the flank position in percutaneous nephrolithotomy (PCNL). We searched PubMed, Embase, SCOPUS, the Cochrane database libraries, and the Chinese Biomedical Literature Database, and randomized controlled trials (RCTs) assessing PCNL in flank position are included in this meta-analysis. The related trials met the inclusion criteria were analyzed using RevMan 5.4. Seven randomized controlled trials were included, involving a total of 587 patients. We found that there was a lower decrease in hemoglobin levels in the flank position group compared to prone-position group (mean difference [MD] = - 0.15, 95% confidence interval (CI) - 0.22 to - 0.08, P < 0.00001). Moreover, our meta-analysis demonstrated no significant differences between groups regarding stone-free rate (relative risk [RR] = 1.00, 95% CI 0.93 to 1.06, P = 0.92), operative time(MD = 0.76, 95% CI - 5.31 to 6.83, P < 0.00001), hospital stay (MD = 0.03, 95% CI - 0.32 to 0.32, P < 0.00001), and complications Clavien grade I (RR = 1.01, 95% CI 0.98 to 1.05, P = 0.54), Clavien grade II (RR = 1, 95% CI 0.97 to 1.02, P = 0.78), and Clavien grade III (RR = 1, 95% CI 0.98 to 1.03, P = 0.77). The use of flank position for PCNL is associated with reduced hemoglobin change without an increase in complications. This positioning technique can be considered safe for patients with nephrolithiasis and may be particularly suitable for high-risk individuals such as those who are obese or have decreased cardiopulmonary function. However, further randomized trials are needed to confirm these findings.

Efficacy of greater occipital nerve block treatment for migraine and potential impact of patient positioning during procedure: Results of randomised controlled trial.

PURPOSE: Assess the efficacy, and potential impact of patient positioning for 10 minutes immediately post-procedure, of greater occipital nerve (GON) block for treatment of migraine. METHODS: Prospective multicentre non-blinded randomised controlled trial, randomisation and treatment of 60 neurology clinic patients with poorly controlled migraine. Outcomes measured with Headache Impact Test-6 (HIT-6), modified MIgraine Disability Assessment Scale (M-MIDAS), and RELIEF scores. RESULTS: Patient positioning did not lead to significant difference in RELIEF score (34% vs 11%, p-value 0.10, Chi-squared test) at day 90. When considered in a multiple regression analysis, the sitting position outperformed supine position significantly (p-value 0.04). However, no significant difference in HIT-6 score between the supine (n = 27) and sitting position groups (n = 33) was detected at baseline (p-value 0.76), day 30 (p-value 0.69) or day 90 (p-value 0.54, Mann-Whitney U-test). The HIT-6 score significantly improved post-GON block, from median 67 (baseline pre-GON) to 59 (day 30) and 62 (day 90) for the supine group and a score of 66, 61-62 for the sitting group (all p-value ≤ 0.001, intra-group comparison using Wilcoxon test); M-MIDAS achieved similar outcomes. Overall, a significant minimal clinically important improvement was obtained with GON block, and the GON injections were deemed very tolerable by patients (median score of 2 on 10 cm pain scale). CONCLUSION: Regardless of patient positioning, GON block is an effective and near-painless procedure for migraine symptom control. Unlike earlier published observational study data, this trial concludes that a sitting patient position immediately post-GON is preferred.

Starting position during colonoscopy: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Traditional teaching has been to place patients in the left lateral decubitus starting position for colonoscopies. Recent randomized controlled trials (RCTs) have compared left lateral decubitus starting position to other approaches. The aim of this systematic review and meta-analysis was to compare different starting positions for colonoscopies and their effect on cecal intubation. METHODS: MEDLINE, Embase, and CENTRAL were searched from inception to July 2023. Articles were eligible for inclusion if they were RCTs comparing at least two different starting positions for adults undergoing colonoscopy. The main outcome was cecal intubation time. Meta-analysis used an inverse variance random effects model. Risk of bias was assessed with the Cochrane Tool for RCTs 2.0. RESULTS: After screening 1523 citations, 14 RCTs were included. Four studies compared left lateral decubitus to right lateral decubitus, four studies compared left lateral decubitus to left lateral tilt-down, three studies compared left lateral decubitus to prone, and three studies compared left lateral decubitus to supine. There were no statistically significant differences in cecal intubation time in seconds across all comparisons: left lateral decubitus vs. right lateral decubitus (MD 14.9, 95% CI - 111.8 to 141.6, p = 0.82, I2 = 85%); left lateral decubitus vs. left lateral tilt-down (MD - 31.3, 95% CI - 70.8 to 8.3, p = 0.12, I2 = 82%); left lateral decubitus vs. prone (MD 17.2, 95% CI - 174.9 to 209.4, p = 0.86, I2 = 94%); left lateral decubitus vs. supine (MD - 149.9, 95% CI - 443.6 to 143.9, p = 0.32, I2 = 89%). CONCLUSION: The starting position for colonoscopies likely does not influence cecal intubation time. This study was limited by heterogeneity.

Body Positions Alter Hemodynamics and Respiration in Healthy Adults: A Systematic Review and Meta-Analysis.

Objective Different body positions can exert both positive and negative physiological effects on hemodynamics and respiration. This study aims to conduct a literature review and examine hemodynamic and respiratory alterations to different body positions.Methods The study protocol was registered with the International Prospective Registry of Systematic Reviews (register no. CRD42021291464). Two independent reviewers evaluated the methodological quality of all included studies using the Down and Black checklist, while the quality of evidence was evaluated using the Grading of Recommendations, Assessment, Development, and Evaluations approach. The overall effects of different body positions were reported from random effects meta-analysis.Results Three studies with low risk of bias and ten with high risk of bias met the eligibility criteria. The supine resulted in the highest cardiac output compared to the 70 deg head-up tilt, sitting, and standing positions (very low- to moderate-quality evidences) and the lowest systemic vascular resistance compared to the 70 deg head-up tilt and standing positions (moderate-quality evidence). Additionally, the supine was associated with the highest total respiratory resistance compared to the 70 deg head-up tilt, left lateral, and standing positions (very low-to moderate-quality evidence) and higher alveolar ventilation than the prone (low-quality evidence).Conclusions The supine position has the most positive association with hemodynamic variables, resulting in the highest cardiac output and the lowest systemic vascular resistance. The upright positions (70 deg head-up tilt and standing positions) has the most positive association with the respiratory variables, resulting in the lowest total respiratory resistance.

Characterization of the IDENTIFYTM surface scanning system for radiation therapy setup on a closed-bore linac.

PURPOSE: In radiation therapy, surface guidance can be used for patient setup and intra-fraction motion monitoring. The surface guided radiation therapy (SGRT) system from Varian Medical systems, IDENTIFYTM, consists of three pods, including cameras and a random pattern projector, mounted on the ceiling. The information captured by the cameras is used to make a reconstruction of the surface. The aim of the study was to assess the technical performance of this SGRT system on a closed-bore linac. METHODS: Phantom measurements were performed to assess the accuracy, precision, reproducibility and temporal stability of the system, both in align and in load position. Translations of the phantoms in lateral, longitudinal, and vertical direction, and rotations around three axes (pitch, roll and yaw) were performed with an accurate, in-house built, positioning stage. Different phantom geometries and different surface colors were used, and various ambient light intensities were tested. RESULTS: The accuracy of the IDENTIFYTM system at the closed-bore linac was 0.07 mm and 0.07 degrees at load position, and 0.06 mm and 0.01 degrees at align position for the white head phantom. The precision was 0.02 mm and 0.02 degrees in load position, and 0.01 mm and 0.02 degrees in align position. The accuracy for the Penta-Guide phantom was comparable to the white head phantom, with 0.06 mm and 0.01 degrees in align position. The system was slightly less accurate for translations of the CIRS lung phantom in align position (0.20 mm, 0.05 degrees). Reproducibility measurements showed a variation of 0.02 mm in load position. Regarding the temporal stability, the maximum drift over 30 min was 0.33 mm and 0.02 degrees in load position. No effect of ambient light level on the accuracy of the IDENTIFYTM system was observed. Regarding different surface colors, the accuracy of the system for a black phantom was slightly worse compared to a white surface, but not clinical relevant. CONCLUSION: The IDENTIFYTM system can adequately be used for motion monitoring on a closed-bore linac with submillimeter accuracy. The results of the performed measurements meet the clinical requirements described in the guidelines of the AAPM and the ESTRO.

[Annual review of clinical research on extracorporeal life support in 2023].

The clinical research in the field of extracorporeal life support (ECLS) in 2023 has focused on the efficacy of veno-arterial extracorporeal membrane oxygenation (ECMO) in patients with infarct-related cardiogenic shock. Additionally, the research also explored the efficacy of prone positioning during veno-venous ECMO, transfusion strategies, and the impact of obesity on outcomes. Awake veno-venous ECMO has shown novel therapeutic potential, but its optimal practice methods and management strategies remain to be determined. In in-hospital cardiac arrest patients, extracorporeal cardiopulmonary resuscitation has demonstrated higher survival rates and better neurological recovery compared to conventional cardiopulmonary resuscitation. The effectiveness of extracorporeal carbon dioxide removal varies among patients with different types of respiratory failure. Future research should focus on optimizing the application strategies and process management of ECLS technologies, investigating personalized therapy, and studying how to improve long-term rehabilitation and quality of life for survivors.

Operative Positioning and Intraoperative-Acquired Pressure Injury: A Retrospective Cohort Study.

OBJECTIVE: To comprehensively assess the association between operative positioning with intraoperative-acquired pressure injury (IAPI) development. METHODS: This retrospective cohort study included 455 patients who underwent surgery between October 2020 and January 2021. The authors grouped patients by operative positioning into the prone position and nonprone position groups. They used propensity-score matching at a 1:2 ratio to control for preoperative confounders, applied multiple logistic regression models to analyze the effects between positioning and IAPI, and assessed interactions of positioning and intraoperative factors on IAPI. RESULTS: The final enrollment was 92 cases in the prone position group and 181 in the nonprone position group. Multivariable logistic analysis suggested that the prone position had a 2.92 times higher risk of IAPI than the nonprone position (odds ratio, 2.92; 95% CI, 1.13-7.57; P = .026). Subgroup analysis showed a significant multiplicative interaction between positioning and foam dressing on IAPI (P < .05), which was not observed in other intraoperative factors (P > .05). CONCLUSIONS: This study provides evidence that prone operative positioning can increase IAPI risk. Patients in the prone position may particularly benefit from using dressings in Chinese populations. Further large-sample longitudinal studies are required to confirm these findings.

Surface guided radiation therapy with an innovative open-face mask and mouth bite: patient motion management in brain stereotactic radiotherapy

Introduction To guarantee treatment reproducibility and stability, immobilization devices are essential. Additionally, surface-guided radiation therapy (SGRT) serves as an accurate complement to frameless stereotactic radiosurgery (SRS) and stereotactic radiotherapy (SRT) by aiding patient positioning and real-time monitoring, especially when non-coplanar fields are in use. At our institute, we have developed a surface-guided SRS (SG-SRS) workflow that incorporates our innovative open-face mask (OM) and mouth bite (MB) to guarantee a precise and accurate dose delivery. Methods This study included 40 patients, and all patients were divided into closed mask (CM) and open-face mask (OM) groups according to different positioning flow. Cone beam computed tomography (CBCT) scans were performed, and the registration results were recorded before and after the treatment. Then Bland–Altman method was used to analyze the consistency of AlignRT-guided positioning errors and CBCT scanning results in the OM group. The error changes between 31 fractions in one patient were recorded to evaluate the feasibility of monitoring during treatment. Results The median of translation error between stages of the AlignRT positioning process was (0.03–0.07) cm, and the median of rotation error was (0.20–0.40)°, which were significantly better than those of the Fraxion positioning process (0.09–0.11) cm and (0.60–0.75)°. The mean bias values between the AlignRT guided positioning errors and CBCT were 0.01 cm, − 0.07 cm, 0.03 cm, − 0.30°, − 0.08° and 0.00°. The 31 inter-fractional errors of a single patient monitored by SGRT were within 0.10 cm and 0.50° (AU)

Intra-abdominal Content Movement in Prone Versus Lateral Decubitus Position Lateral Lumbar Interbody Fusion (LLIF).

STUDY DESIGN: A prospective, anatomical imaging study of healthy volunteer subjects in accurate surgical positions. OBJECTIVE: To establish if there is a change in the position of the abdominal contents in the lateral decubitus (LD) versus prone position. SUMMARY OF BACKGROUND DATA: Lateral transpsoas lumbar interbody fusion (LLIF) in the LD position has been validated anatomically and for procedural safety, specifically in relation to visceral risks. Recently, LLIF with the patient in the prone position has been suggested as an alternative to LLIF in the LD position. MATERIALS AND METHODS: Subjects underwent magnetic resonance imaging of the lumbosacral region in the right LD position with the hips flexed and the prone position with the legs extended. Anatomical measurements were performed on axial magnetic resonance images at the L4-5 disc space. RESULTS: Thirty-four subjects were included. The distance from the skin to the lateral disc surface was 134.9 mm in prone compared with 118.7 mm in LD ( P <0.0001). The distance between the posterior aspect of the disc and the colon was 20.3 mm in the prone compared with 41.1 mm in LD ( P <0.0001). The colon migrated more posteriorly in relation to the anterior margin of the psoas in the prone compared with LD (21.7  vs . 5.5 mm, respectively; P <0.0001). 100% of subjects had posterior migration of the colon in the prone compared with the LD position, as measured by the distance from the quadratum lumborum to the colon (44.4  vs . 20.5 mm, respectively; P <0.001). CONCLUSION: There were profound changes in the position of visceral structures between the prone and LD patient positions in relation to the LLIF approach corridor. Compared with LD LLIF, the prone position results in a longer surgical corridor with a substantially smaller working window free of the colon, as evidenced by the significant and uniform posterior migration of the colon. Surgeons should be aware of the potential for increased visceral risks when performing LLIF in the prone position. LEVEL OF EVIDENCE: Level II-prospective anatomical cohort study.

Dynamic changes in lung water density and volume following supine body positioning.

PURPOSE: Measure the changes in relative lung water density (rLWD), lung volume, and total lung water content as a function of time after supine body positioning. METHODS: An efficient ultrashort-TE pulse sequence with a yarnball k-space trajectory was used to measure water density-weighted lung images for 25 min following supine body positioning (free breathing, 74-s acquisitions, 3D images at functional residual capacity, 18 time points) in 9 healthy volunteers. Global and regional (10 chest-to-back positions) rLWD, lung volume, and total lung water volume were measured in all subjects at all time points. Volume changes were validated with a nitrogen washout study in 3 participants. RESULTS: Global rLWD increased significantly (p = 0.001) from 31.8 ± 5.5% to 34.8 ± 6.8%, while lung volumes decreased significantly (p < 0.001) from 2390 ± 620 mL to 2130 ± 630 mL over the same 25-min interval. Total lung water volume decreased slightly from 730 ± 125 mL to 706 ± 126 mL (p = 0.028). There was a significant chest-to-back gradient in rLWD (20.7 ± 4.6% to 39.9 ± 6.1%) at all time points with absolute increases of 1.8 ± 1.2% at the chest and 5.4 ± 1.9% at the back. Nitrogen washout studies yielded a similar reduction in lung volume (12.5 ± 0.9%) and time course following supine positioning. CONCLUSION: Lung volumes during tidal breathing decrease significantly over tens of minutes following supine body positioning, with corresponding increases in lung water density (9.2 ± 4.4% relative increase). The total volume of lung water is slightly reduced over this interval (3.3 ± 4.0% relative change). Evaluation of rLWD should take time after supine positioning, and more generally, all sources of lung volume changes should be taken into consideration to avoid significant bias.

Diameters of the optic sheath and superior ophthalmic vein can expand and contract at positional changes: a magnetic resonance imaging study.

PURPOSE: This study aimed to explore the diameters of the optic sheath (OSD) and superior ophthalmic vein (SOVD) in response to positional changes using magnetic resonance imaging (MRI). MATERIALS AND METHODS: Fifty adult outpatients who presented to the hospital underwent thin-slice coronal T2-weighted MRI in the supine position followed by the prone position. RESULTS: The OS and SOV were well delineated in all the patients. The OSD in the anterior orbit was measured in the supine and prone positions on both sides. In addition, the SOVD in the anterior and posterior orbits was measured in the supine and prone positions on both sides. The OSD demonstrated an increase on both sides in 100% of the cases. The SOVD demonstrated an increase on both sides in 94% of the cases, whereas the remaining 6% demonstrated a decrease. The OSD measured at the anterior orbit and the SOVD at the anterior and posterior orbits significantly increased on both sides with positional changes from the supine to the prone position. CONCLUSION: OSD and SOVD may expand and contract in response to alterations in the intracranial pressure and venous flow patterns. MRI examination in the supine position combined with positional changes can help to better understand the OS and SOV as dynamic structures.

Changes in the corrected carotid flow time can predict spinal anesthesia-induced hypotension in patients undergoing cesarean delivery: an observational study.

PURPOSE: Spinal anesthesia is a standard technique for cesarean delivery; however, it possesses a risk of hypotension. We hypothesised that the changes in the corrected flow time induced by the Trendelenburg position could predict the incidence of hypotension after spinal anesthesia for cesarean delivery. METHODS: Patients undergoing elective cesarean delivery under spinal anesthesia were enrolled. Before anesthesia induction, corrected flow time was measured in the supine and Trendelenburg positions (FTc-1 and FTc-2, respectively). Additionally, a percent change in corrected flow time induced by the Trendelenburg position was defined as ΔFTc. The primary endpoint was to investigate the ability of ΔFTc to predict the incidence of spinal anesthesia-induced hypotension until delivery. The receiver operating characteristics curves to assess the ability of FTc-1, FTc-2, and ΔFTc to predict the incidence of hypotension were generated. RESULTS: Finally, 40 patients were included, and of those, 26 (65%) developed spinal anesthesia-induced hypotension. The areas under the curve for FTc-1, FTc-2, and ΔFTc were 0.591 (95% CI: 0.424 to 0.743) (P = 0.380), 0.742 (95% CI: 0.579 to 0.867) (P = 0.004), and 0.882 (95% CI: 0.740 to 0.962) (P < 0.001) respectively, indicating ΔFTc as the best predictor among these three parameters. The best threshold for ΔFTc was 6.4% (sensitivity: 80.8% (95% CI: 53.8 to 96.2), specificity: 85.7% (95% CI: 42.9 to 100.0)). CONCLUSIONS: This study demonstrated that changes in the corrected carotid flow time induced by the Trendelenburg position could serve as a good predictor of spinal anesthesia-induced hypotension for cesarean delivery.