Significant Pressure Reduction Research Articles

A new tunnel drainage system using double-adhesive spray-applied membrane: key parameters and applicable scope

To address water leakage in tunnels with high water pressure, a new waterproof drainage system was proposed. The system uses a spray-applied material with double-adhesive properties as a waterproof layer, significantly reducing leakages, and incorporates a unique bottom drainage system to reduce water pressure. In order to check the effectiveness of the new drainage system and to analyze the effects of various structural measures on pressure reduction, a numerical seepage analysis was carried out under the conditions of a water head of 160 m and a surrounding rock permeability of 1 × 10−6 m/s. The results show that the maximum water pressure on the secondary lining is 0.6 MPa, which is about 60% reduction compared to a fully enclosed waterproof system and shows a significant pressure reduction. The spacing of the circumferential drainage pipe and the width of the drainage sheet significantly affect the drainage performance, while the arrangement of the drainage system and the size of the bottom drainage pipe have minimal impact. With full consideration of pressure reduction, cost efficiency and construction feasibility, it is recommended to use the following drainage scheme for iterative calculations during the design stage: “1” shaped arrangement, blind pipe diameter of 10 cm, width of drainage sheets of 0.8 m, and drainage spacing of 6 m. By combining the experimentally determined hydrostatic peel-off strength of 1.4 MPa for spray-applied membrane, the applicable scope of the new drainage system was acquired. The research results can provide valuable insights into the application of spray-applied waterproofing membrane in drainage tunnels with high water pressure.

Flow restoration during mechanical thrombectomy for large vessel occlusion is associated with an immediate reduction of systemic blood pressure.

Managing blood pressure in patients with large vessel occlusion affects infarct size and clinical outcomes. We examined how restoring blood flow impacts systemic blood pressure during mechanical thrombectomy. Patients with large vessel occlusion in the anterior circulation undergoing mechanical thrombectomy between June 2016 and January 2018 were screened. We included those treated under local anesthesia or conscious sedation and analyzed standardized anesthesia protocols to assess systolic and diastolic blood pressure levels throughout the procedure. The primary outcome was the change of blood pressure, compared 5 min before versus 5 min after the last recanalization attempt. Successful reperfusion was defined as Thrombolysis in Cerebral Infarction score ⩾ 2b. Of 134 patients, 117 (87%) achieved successful angiographic reperfusion, showing a notable systolic blood pressure drop 5 min after flow restoration (10.2 ± 14.6 vs 3.24 ± 8.65 mm Hg, p = 0.009). Successful angiographic reperfusion was a significant predictor for this decrease in multivariable logistic regression: OR = 1.34 (95% CI: 1.03-1.73, p = 0.0299). Among 66 patients not given circulation-affecting meds, a significant systolic pressure reduction was also observed (155 ± 17 mm Hg to 148 ± 17 mm Hg ; p < 0.001). No diastolic pressure changes were significant. Flow restoration was associated with an immediate reduction of systolic blood pressure values in patients undergoing mechanical recanalization under local anesthesia or conscious sedation. This suggests a complex interplay between endovascular stroke therapy and cardiovascular hemodynamics.

NO-cGMP-K+ Channels Pathways Participate in the Antihypertensive Effects of Attalea phalerata Martius ex Spreng Oil-Loaded Nanocapsules.

Attalea phalerata Martius ex Spreng is a palm tree that is widely distributed in the Central-West region of Brazil. In this study, we investigated whether the oil-loaded nanocapsules of A. phalerata (APON) have acute and long-lasting antihypertensive effects in male spontaneously hypertensive rats (SHR), as well as explored the underlying molecular mechanisms. APON was prepared using the interfacial polymer deposition method. The particle size, polydispersity index, and zeta potential were investigated using dynamic and electrophoretic light scattering. The antihypertensive effects of APON (administered at doses of 1, 3, and 10 mg/kg) were evaluated after acute intraduodenal administration and after 7 days of oral treatment. To investigate the molecular pathways involved, we used pharmacological antagonists and inhibitors that target prostaglandin/cyclic adenosine monophosphate, nitric oxide/cyclic guanosine monophosphate, and potassium channels. Both acute and prolonged administration of APON (at doses of 3 and 10 mg/kg) resulted in a significant reduction in systolic, diastolic, and mean arterial pressure. Prior treatment with a non-selective nitric oxide synthase inhibitor (Nω-nitro-L-arginine methyl ester), guanylyl cyclase inhibitor (methylene blue), or non-selective calcium-sensitive K+ channel blocker (tetraethylammonium) abolished the antihypertensive effects of APON. Our study showed that A. phalerata oil-loaded nanocapsules have a significant antihypertensive effect in SHR after both short-term and long-term (7-day) use. This effect seems to rely on the vascular endothelium function and involves the NO-cGMP-K+ channel pathway. This research suggests a new direction for future studies to definitively prove the therapeutic benefits of APON in treating cardiovascular disease.

Does plantar pressure in short-term standing differ between modular insoles selected based upon preference or matched to self-reported foot shape?

Prolonged workplace standing is commonplace and associated with a range of lower limb issues. Evaluating footwear interventions aiming to modify plantar pressure during standing is essential as the body is static, creating a different requirement for footwear. Previous research associates medial midfoot pressure with greater perceived comfort and identifies arch height as the most variable element of foot shape. Targeting footwear mass customization within this area may better address differences within the target wearers. This study aims to evaluate a modular insole system for its ability to modify plantar pressure during standing. Twenty-five participants completed a static and dynamic standing protocol for 60 seconds whilst measuring in-shoe peak and mean plantar pressure (KPa) and contact area (%). Individuals wore three insole options targeted towards different medial arch shapes (A– low arch, B– medium arch, C– high arch) and rated them for comfort. Participants received guidance to self-identify foot shape (low, medium, or high arch). Comparisons were drawn across the three insole profiles and between the insole rated as most comfortable (preferred), and the insole that matched the self-identified foot shape (matched). As insole arch height increased, medial midfoot pressure and contact area significantly increased, alongside significant reductions in first metatarsal pressure and contact. Preference was spread across insoles A, B, and C (56%, 32%, 12% of participants, respectively). Sixteen participants had different matched and preferred insoles, with significantly greater medial midfoot pressure and contact in the matched insole. The modular insole enabled different wear experiences, however, results suggest that individuals selected insoles lower than their foot shape. Providing adequate medial arch support enables redistribution of pressure which may enable greater comfort during the workday.

Plantar pressure reduction in the heel region through self-adjusting insoles with a heel cup in standard and individualized rocker shoes

BackgroundEffectiveness of therapeutic footwear in reducing peak pressure in persons with diabetes and loss of protective sensation to prevent diabetic foot ulcers varies due to manual production and possible changing foot structure. A previous two-way approach to address this issue, featuring individualized 3D-printed rocker midsoles and self-adjusting insoles, proved effective in the forefoot but less in the heel. To address this, new insoles incorporating a heel cup are developed. MethodsIn-shoe pressure was measured, while persons with diabetes and loss of protective sensation with high peak pressure (≥ 200 kPa) in the heel walked on a treadmill with control and individualized rocker shoe paired with control and new insole. FindingsGeneralized estimating equations revealed significant decrease in peak pressure in the proximal heel with the new insole alone and combined with rocker shoe compared to rocker shoe alone. For the distal heel, significant decrease in peak pressure is shown with the combination of new insole and rocker shoe compared to control shoe. For the forefoot and toes (excluding hallux) significant decrease in peak pressure is shown using the rocker shoe alone or combined with the heel cup compared to control shoe. InterpretationThe new insole paired with rocker shoe is effective in reducing peak pressure in the distal heel. To have similar (or more) success in proximal heel, one could replace the rocker midsole with more compliant materials. The rocker shoe used separately or combined with a heel cup effectively reduces the peak pressure in the forefoot and other toes.

EVALUATION OF CAST SPLITTING ON LOWER LEG COMPARTMENT PRESSURES: A PILOT STUDY IDENTIFYING THE MOST EFFECTIVE SPLITTING TECHNIQUE

IntroductionLower limb immobilisation with full casts is commonly used to manage fractures. There may be the need to split casts in an emergency, such as compartment syndrome, with no current consensus as to which technique is most effective in reducing pressure quickly. Our study aims to compare the reduction in pressure across lower leg compartments using three different cast splitting techniques.MethodsThis study was done on a volunteer doctor. Pressure sensors were positioned at the anterior, posterior and lateral compartments. A single plaster technician applied below knee full casts with sequential layering and were allowed to dry as per manufacture instructions. Cast were split utilising three splitting methods; bivalve, tramline and single split and measurements taken when each layer was split. We compared results of ten repetitions for each splitting technique.ResultsWhen the cast was initially cut there were significant reduction in pressure with the bivalve split (20.6 ± 0.76 N) when compared to both the single split (26.8 ± 1.13 N, P &lt; 0.001) and tramline split (26.4 ± 0.90 N, P &lt; 0.001). When the cast was spread there were significant reduction in pressure with the bivalve split (10.7 ± 0.83 units) when compared to both the single split (14.6 ± 0.85 N, P &lt; 0.001) and tramline split (16.6 ± 0.77 N, P &lt; 0.001). When the final layer of wool was released the pressure remained lower (statistically significant) in the bivalve split compared to both single split and tramline split.ConclusionOur study demonstrates that bivalve cast splitting provided a more rapid reduction in pressure compared to other techniques across all three compartments. Our data shows that once down to skin, bivalve splitting continues to provide the lowest pressure compared to the other techniques. We recommend utilising bivalve when splitting a cast in an emergency.

Induced fatigue impact on plantar pressure in females with mild hallux valgus

Fatigue has been established to change plantar pressure distribution, yet its impact on hallux valgus (HV) patients, who exhibit morphological and biomechanical changes in the foot, remains insufficiently studied. Twenty-eight female participants, comprising 16 with mild HV and 12 healthy controls, were recruited. Plantar pressures were recorded pre- and post-fatigue using the Footscan platform during self-selected-speed walking trials, fatigue protocol was performed on a treadmill. Foot was segmented into 10 anatomical regions for calculating parameters including maximal force, peak pressure, impulse, contact duration, contact area, and force time-series, alongside assessing the distribution of medial and lateral contact forces (Foot balance) across the groups. During post-fatigue, patients with mild HV demonstrated adaptive changes in plantar pressure distinct from healthy controls, with significant reductions in maximal force, peak pressure, and impulse in the M1 and M2 regions and increases in the M3–M5 regions. In contrast, the control group exhibited an opposite pattern, concentrating pressure in the M1 and M2 regions post-fatigue. The force time-series analysis revealed significant disparities between HV patients and controls, particularly in the M4 and M5 regions, where HV patients showed a less pronounced and lower passive peak in forces. Results show that women with mild HV demonstrate adaptive changes in plantar pressure post-fatigue, distinctly different from healthy individuals, aiding in preventive strategies for fatigue-induced foot injuries for HV patients.

Airway pressure release ventilation (APRV) versus pressure support ventilation (PSV)-A prospective intervention trial comparing haemodynamic parameters in intensive care patients.

Assisted mechanical ventilation may alter the pressure profile in the thorax compared to normal breathing, which can affect the blood flow to and from the heart. Studies suggest that in patients with severe lung disease, airway pressure release ventilation (APRV) may be haemodynamically beneficial compared to other ventilator settings. The primary aim of this study was to investigate if APRV affects cardiac index in intubated intensive care patients without severe lung disease when compared to pressure support ventilation (PSV). The secondary aim comprised potential changes in other haemodynamic and ventilatory parameters. Twenty patients were enrolled in the intensive care unit (ICU) at Sahlgrenska University Hospital. Eligible patients met the inclusion criteria; 18 years of age or above, intubated and mechanically ventilated, triggering and stable on PSV mode, with indwelling haemodynamic monitoring via a pulse-induced continuous cardiac output (PiCCO) catheter. The study protocol started with a 30-min interval on PSV mode, followed by a 30-min interval on APRV mode, and finally a 30-min interval back on PSV mode. At the end of each interval, PiCCO outputs, ventilator outputs, arterial and venous blood gas analyses, heart rate and central venous pressure were recorded and compared between modes. There was no significant difference in cardiac index (3.42 vs. 3.39 L/min/m2) between PSV and APRV, but a significant increase in central venous pressure (+1.0 mmHg, p = .027). Furthermore, we found a significant reduction in peak airway pressure (-3.16 cmH2O, p < .01) and an increase in mean airway pressure (+2.1 cmH2O, p < .01). No statistically significant change was found in oxygenation index (partial pressure of O2 [pO2]/fraction of inspired oxygen) nor in other secondary outcomes when comparing PSV and APRV. There was no significant association between global end-diastolic volume index and cardiac index (R2 = 0.0089) or central venous pressure (R2 = 0.278). All parameters returned to baseline after switching the ventilator mode back to PSV. We could not detect any changes in cardiac index in ICU patients without severe lung disease during APRV compared to PSV mode, despite lower peak airwaypressure and increasedmean airway pressure.

Clinical, Functional, and Quality-of-Life Outcomes after Computer Assisted Vacuum Thrombectomy for Pulmonary Embolism: Interim Analysis of the STRIKE-PE Study

PurposeTo report the first interim analysis of the STRIKE-PE study, evaluating the safety and effectiveness of computer assisted vaccum thrombectomy (CAVT) for the treatment of acute pulmonary embolism (PE). Materials and MethodsThis prospective, international, multicenter study will enroll 600 adult patients with acute PE of ≤14 days and a right ventricle (RV)–to–left ventricle (LV) ratio of ≥0.9 who receive first-line endovascular treatment with CAVT using the Indigo Aspiration System (Penumbra, Alameda, California). Primary endpoints are change in RV/LV ratio and incidence of composite major adverse events (MAEs) within 48 hours. Secondary endpoints include functional and quality-of-life (QoL) assessments. ResultsThe first 150 consecutive patients were treated with 12F catheter CAVT. Mean age was 61.3 years, 54.7% were men, 94.7% presented with intermediate-risk PE, and 5.3% presented with high-risk PE. Median thrombectomy and procedure times were 33.5 minutes and 70.0 minutes, respectively, resulting in a mean reduction in systolic pulmonary artery pressure of 16.3% (P < .001). Mean RV/LV ratio decreased from 1.39 to 1.01 at 48 hours, a 25.7% reduction (P < .001). Four (2.7%) patients experienced a composite MAE within 48 hours. At 90-day follow-up, patients exhibited statistically significant improvements in the Borg dyspnea scale score and QoL measures, and the New York Heart Association class distribution returned to that reported before the index PE. ConclusionsInterim results from the STRIKE-PE study demonstrate a significant reduction in pulmonary artery pressure and RV/LV ratio, a median thrombectomy time of 33.5 minutes, a composite MAE rate of 2.7%, and significant improvements in 90-day functional and QoL outcomes.

Sacubitril/valsartan has an underestimated impact on the right ventricle in patients with sleep-disordered breathing, especially central sleep apnoea syndrome

BackgroundSacubitril/valsartan has been demonstrated to significantly improve left ventricular performance and remodelling in patients with heart failure. However, its effects on the right ventricle in patients with chronic heart failure and sleep-disordered breathing (SDB) have not been studied. AimTo investigate the impact of sacubitril/valsartan treatment on right ventricular function in patients with SDB. MethodsThis was a subanalysis of an observational prospective multicentre study involving 101 patients. At inclusion, patients were evaluated by echocardiography and nocturnal ventilatory polygraphy, which allowed patients to be divided into three groups: “central-SDB”; “obstructive-SDB”; and “no-SDB”. ResultsAfter 3 months of sacubitril/valsartan therapy, a positive impact on right ventricular function was observed. In the general population, tricuspid annular plane systolic excursion increased by +1.32±4.74mm (P=0.024) and systolic pulmonary artery pressure decreased by −3.1±10.91mmHg (P=0.048). The central-SDB group experienced the greatest echocardiographic improvement, with a significant increase in tricuspid annular plane systolic excursion of +2.1±4.9mm (P=0.045) and a significant reduction in systolic pulmonary artery pressure of −8.4±9.7mmHg (P=0.001). ConclusionsSacubitril/valsartan improved right ventricular function in patients with heart failure and SDB after only 3 months of treatment. The greatest improvement in right ventricular function was observed in the central-SDB group.

Cyclical hydraulic pressure pulses reduce breakdown pressure and initiate staged fracture growth in PMMA

Using unique experimental equipment on large bench-scale samples of Polymethylmethacrylate, used in the literature as an analogue for shale, we investigate the potential benefits of applying cyclical hydraulic pressure pulses to enhance the near-well connectivity through hydraulic fracturing treatment. Under unconfined and confined stresses, equivalent to a depth of up to 530 m, we use dynamic high-resolution strain measurements from fibre optic cables, complemented by optical recordings of fracture development, and investigate the impact of cyclical hydraulic pressure pulses on the number of cycles to failure in Polymethylmethacrylate at different temperatures. Our results indicate that a significant reduction in breakdown pressure can be achieved. This suggests that cyclic pressure pulses could require lower power consumption, as well as reduced fluid injection volumes and injection rates during stimulation, which could minimise the occurrence of the largest induced seismic events. Our results show that fractures develop in stages under repeated pressure cycles. This suggests that Cyclic Fluid Pressurization Systems could be effective in managing damage build-up and increasing permeability. This is achieved by forming numerous small fractures and reducing the size and occurrence of large fracturing events that produce large seismic events. Our results offer new insight into cyclical hydraulic fracturing treatments and provide a unique data set for benchmarking numerical models of fracture initiation and propagation.

Venous sinus stenting for idiopathic intracranial hypertension: An updated Meta-analysis

BackgroundIdiopathic intracranial hypertension (IIH) is characterized by elevated intracranial pressure and primarily affects obese women of reproductive age. Venous sinus stenting (VSS) is a surgical procedure used to treat IIH, but its safety and efficacy are still controversial. MethodsA systematic review and meta-analysis were conducted following PRISMA guidelines. Multiple databases were searched for studies evaluating the safety and efficacy of VSS in IIH patients and meta-analysis was performed to pool the data. ResultsA total of 36 studies involving 1066 patients who underwent VSS were included. After VSS, a significant reduction in trans-stenotic gradient pressure was observed. Patients also showed significantly lower cerebrospinal fluid (CSF) opening pressure. Clinical outcomes demonstrated improvement in tinnitus (95%), papilledema (89%), visual disturbances (88%), and headache (79%). However, 13.7% of patients experienced treatment failure or complications. The treatment failure rate was 8.35%, characterized by worsening symptoms and recurrence of IIH. The complications rate was 5.35%, including subdural hemorrhage, urinary tract infection, stent thrombus formation, and others. ConclusionVSS appears to be a safe and effective treatment option for IIH patients who are unresponsive to medical therapy or have significant visual symptoms. However, long-term outcomes and safety of the procedure require further investigation.

Efficacy and safety of Usights UC100 illuminated microcatheter in microcatheter-assisted trabeculotomy.

To evaluate the efficacy and safety of Usights UC100 illuminated microcatheter in microcatheter-assisted trabeculotomy (MAT). Totally 10 eyes of 10 patients with primary open angle glaucoma (POAG) who underwent MAT facilitated by Usights UC100 (5 eyes) or iTrack (5 eyes) were reviewed. The success of this surgery was defined as intraocular pressure (IOP) <22 mm Hg with >30% reduction, without oral glaucoma medications, or additional glaucoma surgery. The mean pre-operative IOP was 25.38±10.22 mm Hg in the Usights UC100 group and 19.98±3.87 mm Hg in the iTrack group. MAT was achieved in all eyes in both groups. The success rates for the Usights UC100 group and iTrack groups were in all and 4 eyes, respectively. Both microcatheters produced a statistically significant reduction in IOP, and eyes using Usights UC100 achieved a lower IOP than the iTrack group at 3mo follow-up (12.58±1.52 and 14.84±1.89 mm Hg, respectively), but no statistical significance was there. No severe side effects were observed in either group. MAT using Usights UC100 or iTrack both achieve significant pressure reduction in cases of POAG, and Usights UC100 is as safe as iTrack.

Rotation-traction manipulation induced intradiskal pressure changes in cervical spine-an in vitro study.

Objective: Evaluate the effect of rotation-traction manipulation on intradiskal pressure in human cervical spine specimen with different force and duration parameters, and compare the intradiskal pressure changes between rotation-traction manipulation and traction. Methods: Seven human cervical spine specimens were included in this study. The intradiskal pressure was measured by miniature pressure sensor implanting in the nucleus pulposus. rotation-traction manipulation and cervical spine traction were simulated using the MTS biomechanical machine. Varied thrust forces (50N, 150N, and 250N) and durations (0.05s, 0.1s, and 0.15s) were applied during rotation-traction manipulation with Intradiscal pressure recorded in the neutral position, rotation-anteflexion position, preloading, and thrusting phases. Futuremore, we documented changes in intradiscal pressure during cervical spine traction with different loading forces (50N, 150N, and 250N). And a comparative analysis was performed to discern the impact on intradiscal pressure between manipulation and traction. Results: Manipulation application induced a significant reduction in intradiscal pressure during preloading and thrusting phases for each cervical intervertebral disc (p < 0.05). When adjusting thrust parameters, a discernible decrease in intradiscal pressure was observed with increasing thrust force, and the variations between different thrust forces were statistically significant (p < 0.05). Conversely, changes in duration did not yield a significant impact on intradiscal pressure (p > 0.05). Additionally, after traction with varying loading forces (50N, 150N, 250N), a noteworthy decrease in intradiscal pressure was observed (p < 0.05). And a comparative analysis revealed that rotation-traction manipulation more markedly reduced intradiscal pressure compared to traction alone (p < 0.05). Conclusion: Both rotation-traction manipulation and cervical spine traction can reduce intradiscal pressure, exhibiting a positive correlation with force. Notably, manipulation elicits more pronounced and immediate decompression effect, contributing a potential biomechanical rationale for its therapeutic efficacy.

Evaluating the Efficacy of Interatrial Shunt Devices in Heart Failure With Preserved Ejection Fraction: A Systematic Review and Meta-Analysis.

Heart failure with preserved ejection fraction (HFpEF) is a prevalent and challenging condition with limited therapeutic options. This meta-analysis aims to assess the feasibility and effectiveness of interatrial shunt devices (IASD) in the treatment of HFpEF, focusing on key hemodynamic parameters and clinical outcomes. Six clinical trials, encompassing 324 patients, were included in this analysis. The results showed a significant reduction in pulmonary capillary wedge pressure (PCWP) at rest after IASD implantation, with a mean difference of 1.55 mm Hg. PCWP during exercise also exhibited a decrease, indicating improved exercise tolerance. However, there was an increase in mean right atrial pressure following IASD implantation. These findings suggest that IASD implementation can effectively lower left atrial pressure, a critical target in HFpEF management. This results in substantial clinical improvements, including enhanced New York Heart Association class, quality of life, and 6-minute walk distance. Echocardiographic assessments revealed a reduction in left ventricular end-diastolic volume index and stable right ventricular changes. The meta-analysis underscores the potential benefits of IASD in ameliorating the symptoms and clinical outcomes of HFpEF patients. The increase in mean right atrial pressure warrants further investigation into its effects on right heart function. Additionally, this analysis emphasizes the need for larger, randomized clinical trials to validate these findings and determine optimal patient selection criteria. IASD implantation holds promise as a therapeutic option for HFpEF, offering the potential to improve the quality of life and functional status of affected patients. However, further research is imperative to confirm its efficacy relative to existing treatments and to address concerns regarding its impact on right heart function. This meta-analysis contributes to a deeper understanding of IASD's role in HFpEF management.

Regulation of throttling distribution and characteristic analysis for a microchannel Joule-Thomson (J-T) cooler

Miniature J-T coolers are applied extensively in electronic devices, cryosurgery and infrared detectors. The utilization of microchannels in miniature J-T coolers can induce a noticeable pressure drop through the recuperative structure, leading to modifications in the refrigeration mechanism. This study delves into the performance and coupling mechanism of throttling and heat exchange. Herein, a microchannel cooler with a noticeable throttling effect throughout the refrigeration process serves as a prototype. The mathematical model is proved with the experiments, thereby exposing limitations in the improvement of the throttling mechanism and the thermodynamic process. The analysis reveals that the backflow exhibits a significant pressure reduction (ΔPl); thus, the utilization ratio of the throttling effect is low. Additionally, further optimization of the thermodynamic process is possible by regulating throttling distribution. The performance and coupling mechanism of throttling and heat exchange with constant working conditions are investigated. The findings reveal that an optimal ratio of ΔPl (14.3 %) yields the lowest cold terminal temperature, which is reduced by up to 38.9 K. In this case, the J-T efficiency and the effectiveness of the recuperative process are observed to peak at 56.7 % and 83.8 %, respectively, indicating the optimal use of the throttling effect and interaction effects. The analysis also suggests that the thermodynamic process has been improved.

Testosterone Replacement Therapy: Effects on Blood Pressure in Hypogonadal Men.

While testosterone therapy can improve the various pathologies associated with adult-onset testosterone deficiency (TD), Summary of Product Characteristics (SPC) of five testosterone preparations caution that treatment may be associated with hypertension. This paper evaluates the impact of testosterone undecanoate (TU) on blood pressure (BP) in men with adult-onset TD. Of 737 men with adult-onset TD in an on-going, observational, prospective, cumulative registry, we studied changes in BP using non-parametric sign-rank tests at final assessment and fixed time points. We used multiple regression analysis to establish factors (baseline BP, age, change/baseline waist circumference [WC] and hematocrit [HCT] and follow-up) potentially associated with BP change in men on TU. TU was associated with significant reductions in systolic, diastolic BP and pulse pressure, regardless of antihypertensive therapy (at baseline or during follow-up), larger reductions were seen with concurrent antihypertensive therapy. In men never on antihypertensive agents, median changes (interquartile range [IQR]) in systolic BP, diastolic BP and pulse pressure were -12.5 (-19.0, -8.0), -8.0 (-14.0, -3.0), and -6.0 (-10.0, -1.0) mmHg, respectively at final assessment, with only baseline BP values inversely associated with these changes (HCT and WC were not significantly associated). In men not on TU, systolic BP, diastolic BP, and pulse pressure significantly increased. In the TU treated men only 1 of the 152 men (not on antihypertensive agents at baseline) were started on antihypertensives during follow-up. In contrast 33 of the 202 men on antihypertensives (at baseline or follow-up) had the antihypertensive agent discontinued by the end of the follow-up. TU was associated with lowering of BP during follow-up irrespective of antihypertensive therapy, with greater reductions in men with higher baseline BP. In the context of SPC warnings, our long-term data provide reassurance on the effect of TU on BP.

Comparison of nebulized ropivacaine (0.75%) with nebulized dexmedetomidine on the hemodynamic response on intubation in patients undergoing surgery under general anesthesia: A comparative randomized double-blind placebo-controlled study.

Laryngoscopy and tracheal intubation lead to sympathetic stimulation resulting in hemodynamic fluctuations. We compared local anesthetic ropivacaine 0.75% with alpha agonist dexmedetomidine through ultrasonic nebulization for direct local action of the drug in the airway. In our randomized study, 180 patients were prospectively assigned to three groups of 60 each: group R (0.75%), group D (1 microgram/kg), and group C (control). The primary objective was to determine whether nebulized ropivacaine or nebulized dexmedetomidine can cause a reduction in stress response to laryngoscopy and intubation. The secondary objectives were to compare the hemodynamic parameters at extubation, cough response at extubation, and postoperative sore throat. A total of 165 patients were analyzed. Demographically, all the groups were similar. Group R and group D were found to significantly attenuate the heart rate (HR) at intubation and extubation when compared to group C (P < 0.05). A significant reduction in mean arterial pressure (MAP) was seen (P < 0.05; group D: 90 ± 18.4 mmHg, group C: 99.5 ± 15.9 mmHg, group R: 92.4 ± 16.1 mmHg). There was a significant reduction in cough response in both groups in comparison with group C at 0 minutes (P value; group C vs group D: <.0001; group C vs group R:.01) and 5 minutes (P value; group C vs group D: <.0001; group C vs group R: <.0001). Preinduction topical use of ropivacaine or dexmedetomidine, through the nebulization route, effectively attenuated the pressor responses when compared to placebo.

Determinant of Dynamics and Interfacial Forces in Ultraprecision Machining of Optical Freeform Surface through Simulation-Based Analysis.

This study delves into the intricacies of ultraprecision machining, particularly in the context of machining optical freeform surfaces using Diamond Turning Machines (DTMs). It underscores the dynamic relationship between toolpath generation, hydrostatic bearing in DTMs, and the machining process. Central to this research is the innovative introduction of Metal Matrix Composites (MMCs) to replace the traditional materials used in designing linear bearings. This strategic substitution aims to dynamically enhance both the accuracy and the quality of the machined optical freeform surfaces. The study employs simulation-based analysis using ADAMS to investigate the interfacial cutting forces at the tooltip and workpiece surface and their impacts on the machining process. Through simulations of STS mode ultraprecision machining, the interfacial cutting forces and their relationship with changes in surface curvatures are examined. The results demonstrate that the use of MMC material leads to a significant reduction in toolpath pressure, highlighting the potential benefits of employing lightweight materials in improving the dynamic performance of the system. Additionally, the analysis of slideway joints reveals the direct influence of interfacial cutting forces on the linear slideways, emphasising the importance of understanding and controlling these forces for achieving higher-precision positioning and motion control. The comparative analysis between steel and MMC materials provides valuable insights into the effects of material properties on the system's dynamic performance. These findings contribute to the existing body of knowledge and suggest a potential shift towards more advanced precision forms, possibly extending to pico-engineering in future systems. Ultimately, this research establishes a new standard in the field, emphasising the importance of system dynamics and interfacial forces in the evolution of precision manufacturing technologies.

Abstract 17687: Left Ventricular Unloading in Pulmonary Hypertension With Impella 5.5 as a Bridge to Heart Transplantation

A 59 year-old male with a history of triple-vessel coronary artery bypass graft surgery, ischemic cardiomyopathy with an implantable cardioverter defibrillator, pre- and post-capillary pulmonary hypertension, severe mitral regurgitation, paroxysmal atrial fibrillation, diabetes mellitus, hypertension was referred for transplant evaluation in the setting of cardiogenic shock despite inotropic support. His initial right heart catheterization showed RAP 21 mmHg, RVP 91/9 mmHg, PAP 88/31 mmHg with a mean of 50 mmHg, PCWP 22 mmHg, PVR 6.6 Wood units, SVR 857 dynes, and CO 4.85 l/min/CI 2.59 l/min/m 2 by thermodilution. His hospital course was complicated by acute renal failure requiring continuous renal replacement therapy. Inotropic support could not be weaned on multiple attempts, and pulmonary and wedge pressures remained significantly elevated despite a trial of inhaled nitric oxide. The patient underwent Impella 5.5 placement to assess the hemodynamic response of unloading the left ventricle. A repeat right heart catheterization showed a RAP 1 mmHg, RVP 42/1 mmHg, PAP 48/13 mmHg with a mean of 26 mmHg, PVR 2.3 Wood units, SVR 829 dynes, and CO 6.75 l/min/CI 3.74 l/min/m 2 by thermodilution. Measurements were obtained with Impella 5.5 at P-8 level, milrinone 0.2 mcg/kg/min, treprostinil 4 ng/kg/min, epoprostenol 1 mg every 6 hours, and sildenafil 10 mg in morning and afternoon and 15 mg in evening. The patient underwent successful heart and kidney transplantation. Post-transplantation right heart catheterization showed persistent pre-capillary pulmonary hypertension with normal filling pressures and CI. His pulmonary hypertension was managed with sildenafil 40 mg three times daily and ambrisentan 10 mg daily. This case demonstrates favorable hemodynamic effects of left ventricular unloading using Impella support with significant reduction in pulmonary vascular pressure to reach candidacy for heart transplantation.