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.

Comparison of patient setup accuracy for optical surface-guided and X-ray-guided imaging with respect to the impact on intracranial stereotactic radiotherapy.

PURPOSE: The objective of this work is to estimate the patient positioning accuracy of a surface-guided radiation therapy (SGRT) system using an optical surface scanner compared to an X­ray-based imaging system (IGRT) with respect to their impact on intracranial stereotactic radiotherapy (SRT) and intracranial stereotactic radiosurgery (SRS). METHODS: Patient positioning data, both acquired with SGRT and IGRT systems at the same linacs, serve as a basis for determination of positioning accuracy. A total of 35 patients with two different open face masks (578 datasets) were positioned using X­ray stereoscopic imaging and the patient position inside the open face mask was recorded using SGRT. The measurement accuracy of the SGRT system (in a "standard" and an SRS mode with higher resolution) was evaluated using both IGRT and SGRT patient positioning datasets taking into account the measurement errors of the X­ray system. Based on these clinically measured datasets, the positioning accuracy was estimated using Monte Carlo (MC) simulations. The relevant evaluation criterion, as standard of practice in cranial SRT, was the 95th percentile. RESULTS: The interfractional measurement displacement vector of the SGRT system, σSGRT, in high resolution mode was estimated at 2.5 mm (68th percentile) and 5 mm (95th percentile). If the standard resolution was used, σSGRT increased by about 20%. The standard deviation of the axis-related σSGRT of the SGRT system ranged between 1.5 and 1.8 mm interfractionally and 0.5 and 1.0 mm intrafractionally. The magnitude of σSGRT is mainly due to the principle of patient surface scanning and not due to technical limitations or vendor-specific issues in software or hardware. Based on the resulting σSGRT, MC simulations served as a measure for the positioning accuracy for non-coplanar couch rotations. If an SGRT system is used as the only patient positioning device in non-coplanar fields, interfractional positioning errors of up to 6 mm and intrafractional errors of up to 5 mm cannot be ruled out. In contrast, MC simulations resulted in a positioning error of 1.6 mm (95th percentile) using the IGRT system. The cause of positioning errors in the SGRT system is mainly a change in the facial surface relative to a defined point in the brain. CONCLUSION: In order to achieve the necessary geometric accuracy in cranial stereotactic radiotherapy, use of an X­ray-based IGRT system, especially when treating with non-coplanar couch angles, is highly recommended.

A positioning approach to upper extremity sonographic evaluation and intervention.

Total supported abduction, or TSA, is a position for ultrasound evaluations and guided interventions of the upper extremity. It provides optimal access to the medial arm through the volar wrist and palmar hand for diagnostic evaluations of the median and ulnar nerves as well as procedures including injections for carpal tunnel syndrome, ulnar neuropathy at the elbow, and stenosing tenosynovitis. It enables ease of both ipsilateral and bilateral evaluations/interventions without the need for significant positional changes by the patient or physician. Incorporation of TSA may enhance clinical efficiency by reducing the amount of time, materials, and space required to provide such services.

The relationship between stone-free and patient position in retrograde intrarenal surgery: a randomized prospective study.

PURPOSE: Residual fragments not removed with urinary stone surgery may become symptomatic. In this context, this study was carried out to investigate the effect of performing retrograde intrarenal surgery, which is conventionally performed in the lithotomy position, in the modified lithotomy position (Trend-side) on stone-free rates following the surgery. METHODS: This prospective study consisted of 100 patients with a single kidney stone smaller than 2 cm between 2021 and 2023. These patients were randomized into two groups of 50 patients each to be operated on in the conventional lithotomy and Trend-side positions. Variables were compared using independent t test for continuous variables and chi-square test for categorical variables. RESULTS: There was no significant difference between the lithotomy and Trend-side position groups in terms of preoperative size, density, location of the stone, and hydronephrosis degree. Stone-free rate was 72% (n = 36) in the lithotomy group and 92% (n = 46) in the Trend-side group. Hence, there was a significant difference between the groups in the stone-free rate in favor of the Trend-side group (p = 0.009). Fragmentation time was statistically significantly shorter in the Trend-side group than in the lithotomy group (34 ± 17 min vs. 43 ± 14 min; p = 0.006). There was no significant difference between the groups in postoperative complication rates. CONCLUSION: Performing retrograde intrarenal surgery in the Trend-side position shortened the duration of fragmentation compared to the lithotomy position and was associated with higher stone-free rates. In conclusion, the Trend-side position can be safely preferred in patients undergoing retrograde intrarenal surgery due to kidney stones.

Interrater Agreement of Height Assessment by Rigid Proctoscopy/Rectoscopy for Rectal Carcinoma.

BACKGROUND: Some guidelines for rectal carcinoma consider 12 cm, measured by rigid endoscopy, to be the cutoff tumor height for optional neoadjuvant chemoradiation therapy. Measuring differences of only a few centimeters may predetermine the choice of further therapy. However, rigid endoscopy may exhibit similar operator dependence to most other clinical examination methods. OBJECTIVES: Evaluation of concordance of rigid rectoscopic tumor height measurements performed by 4 experienced examiners, 2 measuring with patients in the lithotomy position and 2 in the left lateral position. Assessment of tumor palpability and distance of the anal verge to the anocutaneous line were also evaluated. DESIGN: This study used a prospective observational design. SETTING: This study was conducted at an academic teaching hospital that is a referral center for colorectal surgery. PATIENTS: There were 50 patients, of whom 35 were men (70%). The median age was 72.5 years (53-88 years). MAIN OUTCOME MEASURES: Interrater agreement of tumor height assessment and tumor height of less than or greater than the 12-cm height limit. RESULTS: With an intraclass correlation coefficient of 0.947 (95% CI, 0.918-0.967, p < 0.001), interrater reliability of tumor height assessment was statistically rated "excellent." Despite this, in 26% of patients, there was no agreement regarding the allocation of the tumor <12- or >12-cm height limit. Furthermore, there was also considerable disagreement concerning tumor palpability and the distance of the anal verge to the anocutaneous line. Patient positioning was not found to influence results. LIMITATIONS: Single-center study. CONCLUSIONS: Rigid rectal endoscopy may not be a sound pivotal basis for the consideration of optional chemoradiation therapy in rectal carcinoma. Application of a universally valid height limit ignores biological variability in body frame, gender, and acquired pelvic descent. Eligibility for neoadjuvant therapy should not rely on height measurements alone. Uniform MRI or CT imaging protocols, based on agreed upon terminology, including factors such as tumor height relative to the pelvic frame and peritoneal reflection, may be an important diagnostic addition to such a decision. See Video Abstract .Clinical trial registration: DRKS00012758 (German National Study Registry), ST-D 406 (German Cancer Society). ACUERDO ENTRE EVALUADORES EN LA EVALUACIN DE LA ALTURA MEDIANTE PROCTO/ RECTOSCOPIA RGIDA PARA EL CARCINOMA DE RECTO: ANTECEDENTES:Algunas guías para el carcinoma de recto consideran que 12 cm, medidos mediante endoscopia rígida, es la altura de corte del tumor para la quimiorradiación neoadyuvante opcional. Por lo tanto, una diferencia de medición de sólo unos pocos centímetros puede predeterminar la elección de una terapia adicional. Sin embargo, la endoscopia rígida puede presentar una dependencia del operador similar a la de la mayoría de los demás métodos de examen clínico.OBJETIVOS:Evaluación de la concordancia de las mediciones de la altura del tumor rectoscópico rígido realizadas por cuatro examinadores experimentados, dos en litotomía y dos en posición lateral izquierda. También se evaluó la evaluación de la palpabilidad del tumor y la distancia del borde anal a la línea anocutánea.DISEÑO:Estudio observacional prospectivo.LUGAR:Hospital universitario, centro de referencia para cirugía colorrectal.PACIENTES:50 pacientes, 35 varones (70%), mediana de edad 72,5 años (53-88 años).PRINCIPALES MEDIDAS DE RESULTADOS:Acuerdo entre evaluadores en la evaluación de la altura del tumor y la asignación del tumor por debajo o más allá del límite de altura de 12 cm.RESULTADOS:Con un coeficiente de correlación intraclase de 0,947 (IC del 95%: 0,918-0,967, p < 0,001), la confiabilidad entre evaluadores de la evaluación de la altura del tumor se calificó estadísticamente como "excelente". A pesar de esto, en el 26% de los pacientes no hubo acuerdo sobre la asignación del tumor por debajo o por encima del límite de 12 cm de altura. Además, también hubo un considerable desacuerdo con respecto a la palpabilidad del tumor y la distancia del borde anal a la línea anocutánea. No se encontró que la posición del paciente influyera en los resultados.LIMITACIONES:Estudio unicéntrico.CONCLUSIONES:La endoscopia rectal rígida puede no ser una base sólida y fundamental para considerar la quimiorradiación opcional en el carcinoma de recto. La aplicación de un límite de altura universalmente válido obviamente ignora la variabilidad biológica en la constitución corporal, el género y el descenso pélvico adquirido. La elegibilidad para la terapia neoadyuvante no debe depender únicamente de las mediciones de altura. Los protocolos uniformes de imágenes por resonancia magnética o tomografía computarizada, basados en una terminología acordada, incluidos factores como la altura del tumor en relación con la estructura pélvica y la reflexión peritoneal, pueden ser una adición diagnóstica importante para tal decisión. (Traducción-Yesenia Rojas-Khalil )Clinical trial registration: DRKS00012758 (German National Study Registry), ST-D 406 (German Cancer Society).

Influence of the examination position and distension medium on the rectal sensory test in patients with functional constipation.

PURPOSE: To evaluate the impact of two different parameters (body position and distension medium) on the rectal sensory test in patients with functional constipation and provide data support for the development of standardized operating procedures in clinical practice. METHODS: Based on a single-center process of the rectal sensory test, 39 patients with functional constipation were recruited for rectal sensory test under different body positions and distension mediums. RESULTS: Among the items of the Constipation Scoring System, the score of frequency of bowel movements showed a negative correlation with the first constant sensation volume (r = -0.323, P = 0.045). Conversely, the score of painful evacuation effort showed a positive correlation with the desire to defecate volume (r = 0.343, P = 0.033). There was a statistically significant difference in the first constant sensation volume (when the distension medium was gas) measured in different body positions (left lateral position, sitting position, squatting position), and the data measured in the squatting position were significantly higher than those in left lateral position (P < 0.05). In terms of research on distension medium, it was found that the first constant sensation volume measured in the squatting position (when the distension medium was water) was significantly lower than that of gas (P < 0.05). CONCLUSION: For patients with functional constipation, there are differences in the results of rectal sensory tests between body positions and distension mediums. When conducting multicenter studies, it is necessary to unify the standard operating procedure (SOP) for operational details to ensure consistency and reliability of the test results.

Physiological and clinical effects of trunk inclination adjustment in patients with respiratory failure: a scoping review and narrative synthesis.

BACKGROUND: Adjusting trunk inclination from a semi-recumbent position to a supine-flat position or vice versa in patients with respiratory failure significantly affects numerous aspects of respiratory physiology including respiratory mechanics, oxygenation, end-expiratory lung volume, and ventilatory efficiency. Despite these observed effects, the current clinical evidence regarding this positioning manoeuvre is limited. This study undertakes a scoping review of patients with respiratory failure undergoing mechanical ventilation to assess the effect of trunk inclination on physiological lung parameters. METHODS: The PubMed, Cochrane, and Scopus databases were systematically searched from 2003 to 2023. INTERVENTIONS: Changes in trunk inclination. MEASUREMENTS: Four domains were evaluated in this study: 1) respiratory mechanics, 2) ventilation distribution, 3) oxygenation, and 4) ventilatory efficiency. RESULTS: After searching the three databases and removing duplicates, 220 studies were screened. Of these, 37 were assessed in detail, and 13 were included in the final analysis, comprising 274 patients. All selected studies were experimental, and assessed respiratory mechanics, ventilation distribution, oxygenation, and ventilatory efficiency, primarily within 60 min post postural change. CONCLUSION: In patients with acute respiratory failure, transitioning from a supine to a semi-recumbent position leads to decreased respiratory system compliance and increased airway driving pressure. Additionally, C-ARDS patients experienced an improvement in ventilatory efficiency, which resulted in lower PaCO2 levels. Improvements in oxygenation were observed in a few patients and only in those who exhibited an increase in EELV upon moving to a semi-recumbent position. Therefore, the trunk inclination angle must be accurately reported in patients with respiratory failure under mechanical ventilation.

Physiological effects and safety of bed verticalization in patients with acute respiratory distress syndrome.

BACKGROUND: Trunk inclination in patients with Acute Respiratory Distress Syndrome (ARDS) in the supine position has gained scientific interest due to its effects on respiratory physiology, including mechanics, oxygenation, ventilation distribution, and efficiency. Changing from flat supine to semi-recumbent increases driving pressure due to decreased respiratory system compliance. Positional adjustments also deteriorate ventilatory efficiency for CO2 removal, particularly in COVID-19-associated ARDS (C-ARDS), indicating likely lung parenchyma overdistension. Tilting the trunk reduces chest wall compliance and, to a lesser extent, lung compliance and transpulmonary driving pressure, with significant hemodynamic and gas exchange implications. METHODS: A prospective, pilot physiological study was conducted on early ARDS patients in two ICUs at CHU Clermont-Ferrand, France. The protocol involved 30-min step gradual verticalization from a 30° semi-seated position (baseline) to different levels of inclination (0°, 30°, 60°, and 90°), before returning to the baseline position. Measurements included tidal volume, positive end-expiratory pressure (PEEP), esophageal pressures, and pulmonary artery catheter data. The primary endpoint was the variation in transpulmonary driving pressure through the verticalization procedure. RESULTS: From May 2020 through January 2021, 30 patients were included. Transpulmonary driving pressure increased slightly from baseline (median and interquartile range [IQR], 9 [5-11] cmH2O) to the 90° position (10 [7-14] cmH2O; P < 10-2 for the overall effect of position in mixed model). End-expiratory lung volume increased with verticalization, in parallel to decreases in alveolar strain and increased arterial oxygenation. Verticalization was associated with decreased cardiac output and stroke volume, and increased norepinephrine doses and serum lactate levels, prompting interruption of the procedure in two patients. There were no other adverse events such as falls or equipment accidental removals. CONCLUSIONS: Verticalization to 90° is feasible in ARDS patients, improving EELV and oxygenation up to 30°, likely due to alveolar recruitment and blood flow redistribution. However, there is a risk of overdistension and hemodynamic instability beyond 30°, necessitating individualized bed angles based on clinical situations. Trial registration ClinicalTrials.gov registration number NCT04371016 , April 24, 2020.

Exploration of postural effects on the external jugular and diploic venous system using upright computed tomography scanning.

PURPOSE: Few studies have investigated the influence of posture on the external jugular and diploic venous systems in the head and cranial region. In this study, we aimed to investigate the effects of posture on these systems using upright computed tomography (CT) scanning. METHODS: This study retrospectively analysed an upright CT dataset from a previous prospective study. In each patient, the diameters of the vessels in three external jugular tributaries and four diploic veins were measured using CT digital subtraction venography in both supine and sitting positions. RESULTS: Amongst the 20 cases in the original dataset, we eventually investigated 19 cases due to motion artifacts in 1 case. Compared with the supine position, most of the external jugular tributaries collapsed, and the average size significantly decreased in the sitting position (decreased by 22-49% on average). In contrast, most of the diploic veins, except the occipital diploic veins, tended to increase or remain unchanged (increased by 12-101% on average) in size in the sitting position compared with the supine position. However, the changes in the veins associated with this positional shift were not uniform; in approximately 5-30% of the cases, depending on each vein, an opposite trend was observed. CONCLUSION: Compared to the supine position, the contribution of external jugular tributaries to head venous drainage decreased in the sitting position, whilst most diploic veins maintained their contribution. These results could enhance our understanding of the physiology and pathophysiology of the head region in upright and sitting positions.

Real-Time Camera Image-Guided Nasoenteric Tube Placement in Prone COVID-19 ICU Patients: A Single-Center Study.

Background & Aims: This study aims to assess the application value of the real-time camera image-guided nasoenteric tube placement in critically ill COVID-19 patients undergoing endotracheal intubation and prone position ventilation therapy. Methods: We enrolled 116 COVID-19 patients receiving endotracheal intubation and prone position ventilation therapy in the intensive care unit (ICU). Patients were randomly divided into the real-time camera image-guided nasoenteric tube placement (n = 58) and bedside blind insertion (n = 58) groups. The success rate, placement time, complications, cost, heart rate, respiratory rate, Glasgow Coma Scale (GCS), and Acute Physiology and Chronic Health Evaluation II (APACHE-II) scores were compared between the 2 groups. Results: For ICU patients with COVID-19 undergoing prone position ventilation therapy, the success rate and cost were significantly higher in the real-time camera image-guided group compared to the bedside blind group (P < .05). The placement time and complication incidence were significantly lower in the real-time camera image-guided group (P < .05). The differences in heart rate, respiratory rate, GCS scores, and APACHE-II scores were insignificant (P > .05). Conclusions: The real-time camera image-guided nasoenteric tube placement system had advantages for ICU COVID-19 patients undergoing prone position ventilation therapy, including a high success rate, short placement time, and no impact on patient position during tube placement. Real-time camera image-guided nasoenteric tube placement can be performed in any position, and demonstrates high efficiency, safety, and accuracy.

Numerical Simulations of the Epley Maneuver With Clinical Implications.

OBJECTIVES: Canalith repositioning procedures to treat benign paroxysmal positional vertigo are often applied following standardized criteria, without considering the possible anatomical singularities of the membranous labyrinth for each individual. As a result, certain patients may become refractory to the treatment due to significant deviations from the ideal membranous labyrinth, that was considered when the maneuvers were designed. This study aims to understand the dynamics of the endolymphatic fluid and otoconia, within the membranous labyrinth geometry, which may contribute to the ineffectiveness of the Epley maneuver. Simultaneously, the study seeks to explore methods to avoid or reduce treatment failure. DESIGN: We conducted a study on the Epley maneuver using numerical simulations based on a three-dimensional medical image reconstruction of the human left membranous labyrinth. A high-quality micro-computed tomography of a human temporal bone specimen was utilized for the image reconstruction, and a mathematical model for the endolymphatic fluid was developed and coupled with a spherical particle model representing otoconia inside the fluid. This allowed us to measure the position and time of each particle throughout all the steps of the maneuver, using equations that describe the physics behind benign paroxysmal positional vertigo. RESULTS: Numerical simulations of the standard Epley maneuver applied to this membranous labyrinth model yielded unsatisfactory results, as otoconia do not reach the frontside of the utricle, which in this study is used as the measure of success. The resting times between subsequent steps indicated that longer intervals are required for smaller otoconia. Using different angles of rotation can prevent otoconia from entering the superior semicircular canal or the posterior ampulla. Steps 3, 4, and 5 exhibited a heightened susceptibility to failure, as otoconia could be accidentally displaced into these regions. CONCLUSIONS: We demonstrate that modifying the Epley maneuver based on the numerical results obtained in the membranous labyrinth of the human specimen under study can have a significant effect on the success or failure of the treatment. The use of numerical simulations appears to be a useful tool for future canalith repositioning procedures that aim to personalize the treatment by modifying the rotation planes currently defined as the standard criteria.

Patient Positioning Assistive Technology Applicable to the Existing Computed Tomography System: Estimation by Pixel Value of Scout Image.

ABSTRACT: This study aimed to propose a patient positioning assistive technique using computed tomography (CT) scout images. A total of 210 patients who underwent CT scans in a single center, including on the upper abdomen, were divided into a study set of 127 patients for regression and 83 patients for verification. Linear regression analysis was performed to determine the R2 coefficient and the linear equation related to the mean pixel value of the scout image and ideal table height (TH ideal ). The average pixel values of the scout image were substituted into the regression equation to estimate the TH ideal . To verify the accuracy of this method, the distance between the estimated table height (TH est ) and TH ideal was measured. The medians of age (in years), gender (male/female), height (in centimeters), and body weight (in kilograms) for the regression and verification groups were 68 versus 70, 85/42 versus 55/28, 163.8 versus 163.0, and 59.9 versus 61.9, respectively. Linear regression analysis indicated a high coefficient of determination ( R2 = 0.91) between the mean pixel value of the scout image and TH ideal . The correlation coefficient between TH ideal and TH est was 0.95 (95% confidence interval, 0.92-0.97; P < 0.0001), systematic bias was 0.2 mm, and the limits of agreement were -5.4 to 5.9 ( P = 0.78). The offset of the table height with TH est was 2.8 ± 2.1 mm. The proposed estimation method using scout images could improve the automatic optimization of table height in CT, and it can be used as a general-purpose automatic positioning technique.

Face-down positioning or posturing after pars plana vitrectomy for macula-involving rhegmatogenous retinal detachments.

BACKGROUND: A macula-involving rhegmatogenous retinal detachment (RRD) is one of the most common ophthalmic surgical emergencies and causes significant visual morbidity. Pars plana vitrectomy (PPV) with gas tamponade is often performed to repair primary macula-involving RRDs with a high rate of anatomical retinal reattachment. It has been advocated by some ophthalmologists that face-down positioning after PPV and gas tamponade helps reduce postoperative retinal displacement. Retinal displacement can cause metamorphopsia and binocular diplopia. OBJECTIVES: The primary objective of this review is to determine whether face-down positioning reduces the risk of retinal displacement following PPV and gas tamponade for primary macula-involving RRDs. SEARCH METHODS: We searched the Cochrane Central Register of Controlled Trials (which contains the Cochrane Eyes and Vision Trials Register) (2022, Issue 11), MEDLINE (January 1946 to 28 November 2022), Embase.com (January 1947 to 28 November 2022), PubMed (1948 to 28 November 2022), Latin American and Caribbean Health Sciences Literature database (1982 to 28 November 2022), ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform. We did not use any date or language restrictions in the electronic search. We last searched the electronic databases on 28 November 2022. SELECTION CRITERIA: We included randomized controlled trials (RCTs) in which face-down positioning was compared with no positioning or another form of positioning following PPV and gas tamponade for primary macula-involving RRDs. DATA COLLECTION AND ANALYSIS: We used standard Cochrane methodology and assessed the certainty of the body of evidence for the prespecified outcomes using the GRADE approach. MAIN RESULTS: We identified three RCTs (369 eyes of 368 participants) that met the eligibility criteria. Two RCTs provided data on postoperative retinal displacement, one reported on postoperative distortion and quality of life outcomes, two on postoperative best-corrected visual acuity (BCVA) in logMAR, and two on postoperative ocular adverse events such as outer retinal folds. Study characteristics and risk of bias All the trials involved predominantly male participants (range: 68% to 72%). Only one trial provided race and ethnicity information, was registered on a trial registry, and reported funding sources. Using the RoB 2 tool, we assessed the risk of bias for proportion of eyes with retinal displacement, mean change in visual acuity, objective distortion scores, quality of life assessments, and ocular adverse events, with most domains judged to be at low risk of bias. Findings Immediate face-down positioning may result in a lower proportion of participants with postoperative retinal displacement compared with support-the-break positioning at six months (risk ratio [RR] 0.73, 95% confidence interval [CI] 0.54 to 0.99; 1 RCT; 239 eyes of 239 participants; very low certainty evidence). One study found no evidence of a difference in BCVA at three months when comparing postoperative face-up with face-down positioning with or without perfluorocarbon liquid (mean difference [MD] -0.03, 95% CI -0.09 to 0.02; I2 = 0; 56 eyes of 56 participants; very low certainty evidence). Immediate face-down positioning appears to have little to no effect on postoperative distortion scores at week 26 (MD 1.80, 95% CI -1.92 to 5.52; 1 RCT; 219 eyes of 219 participants; very low certainty evidence) and postoperative quality of life assessment scores at week 26 (MD -1.80, 95% CI -5.52 to 1.92; 1 RCT; 217 eyes of 217 participants; very low certainty evidence). Adverse events One study that enrolled 262 participants with macula-involving RRDs suggested that immediate face-down positioning after PPV and gas tamponade may reduce the ocular adverse event of postoperative outer retinal folds at six months (RR 0.39, 95% CI 0.17 to 0.90; 1 RCT; 262 eyes of 262 participants; very low certainty evidence) and binocular diplopia (RR 0.20, 95% CI 0.04 to 0.90; 1 RCT; 262 eyes of 262 participants; very low certainty evidence) compared with support-the-break positioning. Immediate face-down positioning may increase the ocular adverse event of elevated intraocular pressure compared with support-the-break positioning (RR 1.74, 95% CI 1.11 to 2.73; 1 RCT; 262 eyes of 262 participants; very low certainty evidence). Another study found no evidence of a difference in postoperative outer retinal folds when comparing face-down versus face-up positioning at one and three months (RR 1.00, 95% CI 0.50 to 2.02; RR 1.00, 95% CI 0.28 to 3.61; 1 RCT; 56 eyes of 56 participants; very low certainty evidence). No studies reported non-ocular adverse events. AUTHORS' CONCLUSIONS: Very low certainty evidence suggests that immediate face-down positioning after PPV and gas tamponade may result in a reduction in postoperative retinal displacement, outer retinal folds, and binocular diplopia, but may increase the chance of postoperative raised intraocular pressure compared with support-the-break positioning at six months. We identified two ongoing trials that compare face-down positioning with face-up positioning following PPV and gas tamponade in participants with primary macula-involving RRDs, whose results may provide relevant evidence for our stated objectives. Future trials should be rigorously designed, and investigators should analyze outcome data appropriately and report adequate information to provide evidence of high certainty. Quality of life and patient preferences should be examined in addition to clinical and adverse event outcomes.

Fluid distribution during surgery in the flat recumbent, Trendelenburg, and the reverse Trendelenburg body positions.

BACKGROUND: The distribution and elimination of infused crystalloid fluid is known to be affected by general anesthesia, but it is unclear whether changes differ depending on whether the patient is operated in the flat recumbent position, the Trendelenburg ("legs up") position, or the reverse Trendelenburg ("head up") position. METHODS: Retrospective data on hemodilution and urine output obtained during and after infusion of 1-2 L of Ringer's solution over 30-60 min were collected from 61 patients undergoing surgery under general anesthesia and 106 volunteers matched with respect to the infusion volume and infusion time. Parameters describing fluid distribution in the anesthetized and awake subjects were compared by population volume kinetic analysis. RESULTS: General anesthesia decreased the rate constant for urine output by 79% (flat recumbent), 91% (legs up) and 91% (head up), suggesting that laparoscopic surgery per se intensified the already strong anesthesia-induced fluid retention. General anesthesia also decreased the rate constant governing the return of the distributed fluid to the plasma by 32%, 15%, and 70%, respectively. These results agree with laboratory data showing a depressive effect of anesthetic drugs on lymphatic pumping, and further suggest that the "legs up" position facilitates lymphatic flow, whereas the "head up" position slows this flow. Both Trendelenburg positions increased swelling of the "third fluid space". CONCLUSIONS: General anesthesia caused retention of infused fluid with preferential distribution to the extravascular space. Both Trendelenburg positions had a modifying influence on the kinetic adaptations that agreed with the gravitational forces inflicted by tilting to body.

Awake proning in patients with COVID-19-related hypoxemic acute respiratory failure: Endorsement by the Scandinavian Society of Anaesthesiology and Intensive Care Medicine.

BACKGROUND: Awake proning in spontaneously breathing patients with hypoxemic acute respiratory failure was applied during the coronavirus disease 2019 (COVID-19) pandemic to improve oxygenation while avoiding tracheal intubation. An updated systematic review and meta-analysis on the topic was published. METHODS: The Clinical practice committee (CPC) of the Scandinavian Society of Anaesthesiology and Intensive Care Medicine (SSAI) assessed the clinical practice guideline "Awake proning in patients with COVID-19-related hypoxemic acute respiratory failure: A rapid practice guideline" for possible endorsement. The Appraisal of Guidelines for REsearch and Evaluation (AGREE) II tool was used. RESULTS: Four out of six SSAI CPC members completed the appraisal. The individual domain totals were: Scope and Purpose 90%; Stakeholder Involvement 89%; Rigour of Development 74%; Clarity of Presentation 85%; Applicability 75%; Editorial Independence 98%; Overall Assessment 79%. CONCLUSION: The SSAI CPC endorses the clinical practice guideline "Awake proning in patients with COVID-19-related hypoxemic acute respiratory failure: A rapid practice guideline". This guideline serves as a useful decision aid for clinicians caring for critically ill patients with COVID-19-related acute hypoxemic respiratory failure and can be used to provide guidance on use of prone positioning in this group of patients.

Echocardiogram by apical-subcostal protocol in prone position during invasive mechanical ventilation in cardiovascular intensive care unit.

AIMS: To evaluate the feasibility of a transthoracic echocardiogram using an apical-subcostal protocol in invasive mechanical ventilation (IMV) and prone position. METHODS: Prospective study of adults who required a prone position during IMV. A pillow was placed only under the left hemithorax in the prone position to elevate and ease the apical and subcostal windows. A critical care cardiologist (prone group) acquired and evaluated the images using the apical-subcostal protocol. Besides, we used ambulatory echocardiograms performed as a comparative group (supine group). RESULTS: 86 patients were included, 43 in the prone and 43 in the supine. In the prone group, the indication to perform an echocardiogram was hemodynamic monitoring. All patients were ventilated with protective parameters, and the mean end-expiratory pressure was 10.6 cmH2O. The protocol was performed entirely in 42 of 43 patients in the prone group because one patient did not have any acoustic window. In the 43 patients in the prone group analyzed and compared to the supine group, global biventricular function was assessed in 97.7% (p = 1.0), severe heart valve disease in 88.4% (p = 0.055), ruled out of the presence of pulmonary hypertension in 76.7% (p = 0.80), pericardial effusion in 93% (p = 0.12), and volume status by inferior vena cava in 93% (p = 0.48). Comparing prone versus supine position, a statistical difference was found when evaluating the left ventricle apical 2-chamber view (65.1 versus 100%, p < 0.01) and its segmental function (53.4 versus 100%, p < 0.01). CONCLUSION: The echocardiogram using an apical-subcostal protocol is feasible in patients in the IMV and prone position.

EVALUATION OF PRONE VERSUS SUPINE POSITIONING IN FRESH RHEGMATOGENOUS RETINAL DETACHMENT TREATED WITH PARS PLANA VITRECTOMY AND GAS.

PURPOSE: To compare Supine versus Prone positioning in fresh rhegmatogenous retinal detachments treated with vitrectomy and gas tamponade. METHODS: This was a prospective randomized controlled trial of 72 eyes with fresh rhegmatogenous retinal detachment that underwent 25-gauge vitrectomy: 37 eyes were allotted supine position and 35 were allotted prone position. Cases were evaluated for single-surgery reattachment rates, best-corrected visual acuity, intraocular pressure, cataract formation, and any complications. The patients were followed up for a period of 3 months. RESULTS: Both groups had similar demographics, and no significant difference was found between the two groups in terms of extent of retinal detachment, position, and number of breaks. The anatomical success after single surgery was 97.3% in the Supine group and 94.3% in the Prone group ( P = 0.609). The best-corrected visual acuity at the end of 3 months was 0.44 ± 0.27 in the Supine group and 0.35 ± 0.27 in the Prone group ( P = 0.119) with a significant increase in best-corrected visual acuity preoperatively from 0.11 ± 0.22 and 0.13 ± 0.22 in Supine and Prone groups, respectively ( P = <0.001). The intraocular pressure in the two groups was comparable at each follow-up. The rates of cataract formation were also similar in the two groups-60% and 53.8% in Supine and Prone groups, respectively ( P = 1.00). Complications such as spikes in intraocular pressure, epiretinal membrane formation, and cystoid macular edema were similar in both groups. CONCLUSION: Rates of retinal reattachment were comparable in both groups showing that supine position is equally safe and effective for adequate tamponade.

Systematic review and meta-analysis of percutaneous nephrolithotomy in flank versus prone position.

BACKGROUND: This systematic review and meta-analysis aimed to evaluate the efficiency and safety of percutaneous nephrolithotomy (PCNL) between flank position and prone position for the treatment of renal stones. METHODS: PubMed, Embase, OVID, and Cochrane Library were comprehensively searched from their inception to Jul 2024. Randomized and nonrandomized trials evaluating renal calculi patients who underwent PCNL via flank position or prone position were included. Data extraction and quality assessment were conducted by two independent reviewers. The outcomes and complications of both groups were compared in this meta-analysis. RESULTS: This review involved five articles (554 patients). Specifically, four articles were randomized controlled trials, and the remaining publication was prospective cohort study. No significant difference was found in stone-free rate between the flank group and prone group after the PCNL procedure. Similarly, the percutaneous access time, operative time, and hospital stay of flank position had no significant difference compared with the prone group. There was no significant difference in the comparison of complication rates between the flank group and the prone group. Although further analysis indicated that patients in the prone position suffered more hemoglobin drop than the flank group, no significant difference was found in the hemorrhage and blood transfusion rates. CONCLUSIONS: Both surgical positions were appropriate for most PCNL procedures and had shown similar efficacy and safety. In practice, the optimal choice should be made according to the patients' conditions and urologists' acquaintance.

Clinical comparison of lateral supine position mini-percutaneous nephrolithotomy and anatrophic nephrolithotomy in the treatment of complete staghorn renal calculi.

BACKGROUND: At present, the guidelines for urology recommend percutaneous nephrolithotomy (PCNL) as the preferred treatment for staghorn renal calculi (SRC). However, for complete SRC, it has been questioned by clinicians and patients due to high residual stone rate, complications, repeated hospitalizations and high treatment cost. Anatrophic nephrolithotomy (ANL) is a traditional and classic method for the treatment of SRC. Due to its high trauma and high technical requirements, it is difficult to carry out in primary hospitals, and gradually replaced by PCNL. The purpose of this study is to compare the efficacy of PCNL and ANL in the treatment of complete SRC. METHODS: Overall, 238 patients with complete SRC were divided into mini-PCNL in lateral supine position group, (n = 190) and ANL group (n = 94) according to treatment for a retrospective cohort study. The calculi parameters, renal function index, comorbidities of calculi, surgical complications, length and frequency of hospitalization, treatment costs, results of postoperative satisfaction survey were compared between the two groups. RESULTS: The risk of the residual stone rate after mini-PCNL in lateral supine position was 239 times (OR = 238.667, P < 0.0001), the number of residual stone 1.3 times (OR = 1.326, P < 0.0001), the amount of residual stone 2.2 times (OR = 2.224, P < 0.0001) that of ANL. The risk of the cost of initial treatment after mini-PCNL in lateral supine position was 3.3 times (OR = 3.273, P < 0.0001), the total cost of treatment 4 times (OR = 4.051, P < 0.0001), the total length of hospital stays 1.4 times (OR = 1.44, P < 0.0001) that of ANL, the incidence of postoperative renal atrophy was 2.2 times (OR = 2.171, P = 0.008) higher in the ANL than in the mini-PCNL in lateral supine position. Glomerular filtration rate (GFR) reduction after ANL was 1.4 times (OR = 1.381, P = 0.037) greater than that after mini-PCNL in lateral supine position at 24-month follow-up. The risk of the overall satisfaction of ANL was 58 times (OR = 57.857, P < 0.0001) higher than that of mini-PCNL in lateral supine position, the number of branches of staghorn greater than 8 is a high risk factor for the occurrence of residual stone after mini-PCNL in lateral supine position (OR = 353.137, P < 0.0001). CONCLUSION: Although the risk of renal atrophy and decreased GFR after ANL is higher than that of mini-PCNL in lateral supine position, the efficacy of traditional ANL in the treatment of complete SRC was generally superior to that of mini-PCNL in lateral supine position. Moreover, number of branches of staghorn greater than 8 are the preferred ANL for complete SRC. TRIAL REGISTRATION: ChiCTR2100047462. The trial was registered in the Chinese Clinical Trial Registry; registration date: 19/06/2021.

Efficacy and safety of video double-lumen tube intubation in lateral position in patients undergoing thoracic surgery: a randomized controlled trial.

BACKGROUND: Video double-lumen tube (VDLT) intubation in lateral position is a potential alternative to intubation in supine position in patients undergoing thoracic surgery. This non-inferiority trial assessed the efficacy and safety of VDLT intubation in lateral position. METHODS: Patients (18-70 yr) undergoing right thoracoscopic lung surgery were randomized to either the left lateral position group (group L) or the supine position group (group S). The VDLT was placed under video larygoscopy. The primary endpoint was the intubation time. Secondary endpoints included VDLT displacement rate, intubation failure rate, the satisfaction of surgeon and nurse, and intubation-related adverse events. RESULTS: The analysis covered 80 patients. The total intubation time was 52.0 [20.4]s in group L and 34.3 [13.2]s in group S, with a mean difference of 17.6 s [95% confidence interval (CI): 9.9 s to 25.3 s; P = 0.050], failing to demonstrate non-inferiority with a non-inferiority margin of 10 s. Group L, compared with group S, had significantly lower VDLT displacement rate (P = 0.017) and higher nurse satisfaction (P = 0.026). No intubation failure occurred in any group. Intubation complications (P = 0.802) and surgeon satisfaction (P = 0.415) were comparable between two groups. CONCLUSIONS: The lateral VDLT intubation took longer time than in the supine position, and non-inferiority was not achieved. The incidence of displacement as the secondary endpoint was lower in the L group, possibly due to changing body positions beforehand. The indication of lateral VDLT intubation should be based on a balance between the safety of airway management and the lower incidence of displacement. TRIAL REGISTRATION: The study was registered at Chictr.org.cn with the number ChiCTR2200064831 on 19/10/2022.