Infusion Pressure Research Articles

Hysteroscopic removal of intrauterine device in early pregnancy

BackgroundIntrauterine devices (IUDs) are commonly used as contraceptives worldwide. However, pregnancies in patients carrying this kind of device may occur. IUD removal when the woman wishes to continue their pregnancy may be very challenging. Only 9 manuscripts in literature reported such similar procedure.Case presentationWe report the case of an hysteroscopic removal of IUD in a young woman at 6 weeks of gestation.DiscussionThe case reported highlights safety and efficacy of operative hysteroscopy as a method of IUD removal in early pregnancy, although other different methods have been reported in literature. In our opinion, maintaining a low infusion pressure during the procedure may help avoiding potential gestational sac damage and IUD displacement for better grasping.

Backflow modeling in nanofluid infusion and analysis of its effects on heat induced damage during magnetic hyperthermia

• Simulate the backflow behavior for nanofluid infusion inside bio-tissue under a geometric nonlinear model. • Investigate the bio-tissue deformation and its effect on the change of material property during nanofluid infusion. • Investigate the interstitial pressure and the local stress distribution inside bio-tissue due to the nanofluid infusion. • Effect of backflow on treatment temperature distribution and heat induced damage for malignant tissue. Although targeted magnetic hyperthermia has been proven to be an effective tumor ablation technique, its use in clinical applications is still scarce particularly due to the difficulty in imposing a desired nanofluid distribution in the therapeutic area. In addition to the inherent difficulty of imposing a distribution with few injection shots, during the nanofluid infusion, the tissue deformation can cause the nanofluid deviation from the targeted injection area and the backflow along the needle can deliver the injected nanofluid to the outer surface of the tissue. Both phenomena can result in an irregular distribution for nanofluid inside bio-tissue. This study develops a poroelastic model considering geometrically nonlinear behavior in order to evaluate the effect of syringe needle size and infusion rate on the backflow. A 26 gauge needle for syringe is used as a typical example to further investigate the nanofluid transport and the change of solid matrix material properties under different infusion rates after comparing the infusion results for several sizes of needle. Finally, the resulting nanofluid concentration distribution obtained with the proposed model is used to simulate the temperature distribution and the cancerous cell damage. The results demonstrate that the infusion pressure and its resulting tissue deformation are the fundamental reasons for obtaining an irregular solution distribution. Tissue deformation induces the increase of porosity and permeability for biomaterials around the tip, and enhances the fluidity of nanofluids inside the tissue. The results also indicate that the increase in backflow length can improve the uniformity of the nanofluid distribution after diffusion and, consequently, the treatment effect. However, it also increases the risk of MNP leakage from the targeted area to the tumor surface, so it is important to keep the backflow rate limited during the injection process.

Zero Phaco: A new technique for dealing with soft cataracts.

Phacoemulsification in soft cataracts can be challenging due to the lack of rigid cleavage planes and the inability to crack. We describe a new phacoemulsification technique for dealing with soft cataracts using high vacuum and zero energy. Following capsulorhexis and hydrodissection, we introduced the phacoemulsification probe, keeping the torsional and longitudinal power at zero. A central groove was created in sculpting mode. We held the nucleus with adequate vacuum in chop mode and divided the nucleus. Then, we rotated and chopped the nucleus similarly into small pieces without using any power. For emulsification, we increased the vacuum to 600 mmHg and then shredded and stuffed the pieces into the phaco probe by the chopper. A newer generation phaco machine with active fluidic system and monitored pressurized infusion helps the surgeon control the intraocular pressure (IOP) and hold the nucleus with vacuum alone, allowing chopping and emulsifying of the pieces without any energy.

Tono-pen and Schiotz tonometer measurements in gas-filled eyes

This study aims to assess the difference between Tono-Pen and Schiotz tonometer measurements in gas-filled eyes and to create a nomogram and equation which can be used to estimate actual intraocular pressure in order to provide a safe IOP level at the end of the surgery. Twenty-two eyes that underwent pars plana vitrectomy were included in the study. Perioperative Tono-Pen and Schiotz tonometer measurements were performed when the eyes were filled with air in the setting of certain vitrectomy infusion pressure levels. Measurements were performed when the eyes were filled with fluid to test the accuracy of the systems. The mean value of the Tono-Pen and Schiotz readings in air-filled eyes corresponding to certain actual intraocular pressure levels were analyzed to create nomograms. Both Tono-Pen and Schiotz tonometers underestimated the actual intraocular pressure set on the screen of the vitrectomy system in the air-filled eyes. The Tono-Pen deviation was 4.5mmHg at a level of 15mmHg actual intraocular pressure, and 16.9mmHg at a level of 55mmHg actual intraocular pressure. The Schiotz tonometer deviation was 10mmHg at a level of 15mmHg actual intraocular pressure, and 8.9mmHg at a level of 55mmHg actual intraocular pressure. All the mean differences between tonometer readings and actual intraocular pressure were statistically significant. (P<0.001) CONCLUSION: To achieve an adequate and safe tamponade at an actual IOP range of 20 - 25mmHg, one should adjust the IOP with Schiotz readings to a level of 9-12mmHg, or Tono-Pen readings to 12-18mmHg.

A novel approach to sclerotomy closure in pars plana vitrectomy: a pilot study

BackgroundMethods of sclerotomy closure following a vitrectomy, including the use of sutures, have been associated with complications such as inflammation, foreign body sensation, and infection. Here, we test an innovative approach to scleral wound closure following pars plana vitrectomy that involves plugging the wound. We investigated several materials with the intent of using products that were either already approved by the FDA for other types of procedures or were biocompatible patient-derived materials.MethodsWe examined whether scleral wounds could be sealed by a clot or internal “plug” rather than a suture or an external adhesive. We tested patient-derived materials (platelet-rich plasma (PRP) and whole blood) as well as polyethylene glycol (PEG) sealant. Whole blood and PRP were prevented from clotting prematurely using sodium citrate, and were clotted for the study with thrombin. Polyethylene glycol (PEG) sealant was prepared according to manufacturer’s recommendations. We used fresh-frozen cadaveric porcine eyes. We tested several methods to form plugs using the above materials, as well as various methods to deliver the plugs into the sclerotomy incisions. We used a novel technique of manual vitrectomy. Successfully generated and implanted clots were tested for efficacy with the Seidel test.ResultsPolyethylene glycol (PEG) sealant fractured during our attempts at molding and inserting the plug. In contrast, both whole blood and PRP yielded successful plugs for insertion. We molded a whole blood clot plug by allowing it to clot inside a 20-gauge angiocath catheter and we successfully delivered it through a 23G trocar. At baseline, no wound leakage was apparent. However, the whole blood clot dislodged during the Seidel test. We successfully molded and delivered a PRP clot plug using a tapered 2-20 μl pipette tip, using MAXGrip Forceps to push it through into the wound. No scleral wound leakage was noted at our baseline physiologic infusion pressure. Furthermore, the PRP clot plug prevented scleral wound leakage up to a pressure of 60 mmHg and was confirmed with the Seidel test.ConclusionOur findings suggest that insertion of a clot plug made from either whole blood or PRP may be an effective strategy for scleral wound closure following pars plana vitrectomy. Further testing in preclinical models is warranted to further refine the materials and methods, since this appears to have the potential to improve the closure of the scleral wounds after pars plana vitrectomy.

33691 Prospective pilot evaluation in Fitzpatrick skin phototypes III to VI of a crystal-free brush-tip exfoliation device with variable vacuum pressure and skin infusion for hyperpigmentation

Unmet needs in skin of color include satisfactory long-term treatments for hyperpigmentation, whether primary or a sequela of various dermatoses. Surveys report that pigmentary disorders are the second most common dermatoses among African American patients consulting dermatologists, and that hyperpigmentation significantly impairs quality of life. This single-center, open-label pilot evaluation prospectively assessed safety, efficacy and tolerability in patients with Fitzpatrick skin phototypes III to VI of an FDA 510(k)-cleared crystal-free brush-tip exfoliation device with adjustable vacuum pressure and skin infusion containing 1% each of alpha-arbutin, glutathione, kojic acid plus azelaic acid; lactic acid; and salix alba bark extract. 23 female patients aged 26 to 71 with mild, moderate or severe facial hyperpigmentation received 3 to 6 treatments at 2 to 4 weekly intervals. Patients applied broad spectrum sunscreen daily. Three weeks after the third treatment, blinded assessment of standardized digital images found that all patients had improvements in skin tone, texture and brightness/radiance (≥2 points on 10-point scales), and 15 (65%) had ≥1 point improvement in pigmentation. Physician and patient GAIS scoring ranged from Improved to Very Much Improved. DQLI improved for 12 (52%). The procedure was well tolerated, with no significant adverse effects. Post-procedural erythema lasted 15 minutes to under 24 hours. All patients reported satisfaction with treatment and increased These pilot data show safety, efficacy and tolerability in skin of color. The ability to patient-tailor all procedural steps, including exfoliation depth, magnitude of vacuum pressure and infusion type, may confer benefits over conventional aluminum oxide crystal microdermabrasion.

Response Guided Slow Infusion of Albumin, Vasoconstrictors and Furosemide Improves Ascites Mobilization and Survival in Acute on Chronic Liver Failure: A Proof-of-Concept Study.

Background and AimsAcute-on-chronic liver failure (ACLF) with increasing organ failure is associated with poor outcomes. Severely deranged systemic hemodynamics and decreased effective arterial blood volume contribute to tissue damage and organ failure. Response-guided therapy with albumin, vasoconstrictors, and furosemide may help overcome effective hypovolemia, improve diuresis and impact survival.MethodsIn the observation cohort, 230 patients with ACLF (CANONIC criteria) with ascites (≥Grade II) and ACLF ≥Grade I were enrolled. A total of 136 patients (GROUP I) received response-guided (urine sodium >80mmol/day) slow albumin-furosemide infusion ± terlipressin (SAFI ± T), while 94 patients (GROUP II) received standard medical therapy. Twenty-eight-day survival, ascites mobilization (nil or grade 1), and adverse events were noted. In another mechanistic cohort (n = 40), laboratory evidences for improvement in various pathophysiological alterations; gut permeability, endotoxemia, cytokine storm, neutrophil dysfunction, and hemodynamic alterations following SAFI ± T/Noradrenaline (NAdr) were evaluated.ResultsAge, gender, CLIF-C-ACLF, SOFA and MELD scores, ACLF grades and urine sodium were not different between the two groups in the observation cohort. Ascites was mobilized in 102/136 in GROUP I (SAFI ± T) and 23/94 in GROUP II (p < 0.05). Twenty-eight-day survival was significantly higher in GROUP I = 103/136 (75.7%) vs GROUP II = 50/94 (53.2%), (P = <0.001). All those who were unable to reach urine sodium >80 mmol/day died. Four patients in GROUP I developed scrotal gangrene. In the mechanistic cohort, 72% of patients survived with significant improvement in gut permeability, endotoxemia, serum cytokines, neutrophil dysfunction, and hemodynamic alterations.ConclusionAscitic fluid mobilization by response-guided SAFI ± T/NAdr therapy improves survival by improving splanchnic and systemic hemodynamics, decreasing gut congestion, gut permeability, and endotoxemia, improving neutrophil functions, and reducing pro-inflammatory cytokines in circulation.

Convection-enhanced delivery with controlled catheter movement: A parametric finite element analysis.

Convection-enhanced delivery (CED) is an investigational method for delivering therapeutics directly to the brain for the treatment of glioblastoma. However, it has not become a common clinical therapy due to an inability of CED treatments to deliver therapeutics in a large enough tissue volume to fully saturate the target region. We have recently shown that the combination of controlled catheter movement and constant pressure infusions can be used to significantly increase volume dispersed (Vd ) in an agarose gel brain tissue phantom. In the present study, we develop a computational model to predict Vd achieved by various retraction rates with both constant pressure and constant flow rate infusions. An increase in Vd is achieved with any movement rate, but increase in Vd between successive movement rates drops off at rates above 0.3-0.35 mm/min. Finally, we found that infusions with retraction result in a more even distribution in concentration level compared to the stationary catheter, suggesting a potential increased ability for moving catheters to have a therapeutic impact regardless of the required therapeutic concentration level.

Novel Technique of 23G Pars Planar Vitrectomy (TPPV) with Alcon Centurion Silver System Gravity -FMS (ACenSS) and ACenSS Vitrectomy Probe (23G) with an External Light Source in Teaching Hospital Rathnapura Sri Lanka

Dual pneumatic 23G vitrectomy cutters of both Alcon Constellation Vision System (AConsVS) and ACenSS have cut rates of 5000 cpm. Aims: To report a novel technique of using ACenSS 23G Vitrectomy cutter for trocar surgery with an external light source in Teaching hospital Rathnapura Sri Lanka from 01/03/2022 to 30/09/2022. Methods: 23G Alcon light probes were used with Retikare (ICON Medicare Tamil Nadu India) external light source for endoillumination. Infusion pressure was set at 65cmH2O (47.81 mmHg) and infusion line connected to eye through a 3 ways tap. ACenSS-GFMS aspiration line connected to aspiration line of vitrectomy probe. Cryopexy used to seal retinal tears as no endolaser facility. Volk surgical corneal lenses with Zeiss Lumera I microscope provided the viewing. ACenSS foot pedal was programmed to 3 modes of vitrectomy with navigation, cutter on/ off function and on/pause of continuous irrigation. A gravity driven another infusion line is used to keep the infusion when endo diathermy is used. Results: When working on maximum cut rate of the ACenSS GFMS (5000 cpm) for long duration machine automatically stops and a restart with reprime needed. Therefore, cut rates were set at a lower rate to work without interruption (core vitrectomy2000 cpm, peripheral trim- 3000cpm and for epinucleus removal 4000 cpm). No retinal traction or ridging of retina was observed at peripheral trim. Total of 210 TPPVs were performed with this technique. Conclusions: 23G TPPV with ACenSS using an external light source is a simple, safe and a cost-effective technique with equal outcome to AConsVS.

Does low infusion pressure microincision cataract surgery (LIPMICS) reduce frequency of post-occlusion breaks?

Objective: To compare the number of surge events and efficacy of phacoemulsification using a near-physiological intraocular pressure (IOP) setting and a standard IOP setting. Materials and methods: The surgical data of patients who underwent phacoemulsification with IOL implantation using the CENTURION Vision System’s Active Fluidics setting and Active Sentry Handpiece (Alcon Laboratories, USA) were analyzed. Results: The study included 181 patients (204 eyes). In Group 1, the IOP was set at 20 mmHg (n=102, 50%), and in Group 2, the IOP was set at 60 mmHg (n=102, 50%). Total case time was significantly lower (p=.036) in Group 1 (0:03:17.20 ± 0:00:34.55 vs. 0:03:28.71 ± 0:00:43.03). There was no statistically significant difference between the mean cumulative dissipated energy (CDE) (7.06 ± 3.20 vs. 7.59 ± 3.26) and mean ultrasound (UJS) time (0:00:36 ± 0:00:12 vs. 0:00:38 ± 0:00:13) between the two groups (p=0.24 and p=0.31, respectively). Active sentry (AS) engaged less often (p<0.001) in Group 1. There was no statistically significant correlation between the CDE and AS activation in Group 1 (p=0.96). A strong statistically significant correlation between the CDE and AS activation (p<0.0001, r=0.61, CI (0.47 to 0.72)) was observed in group 2. Conclusion: During phacoemulsification, surge events are more likely to occur when operating at high IOP settings.Abbreviations: LIPMICS = low infusion pressure microincision cataract surgery, IOP = intraocular pressure, CDE = cumulative dissipated energy, UJS = mean ultrasound time, AS = Active sentry, LOCS = Lens Opacities Classification System, NO = nuclear opalescence, AFR = aspiration flow rate

A witnessed intra-operative blood transfusion-related air embolism under epidural anaesthesia for vesicovaginal fistula repair

The transfusion is a normal life-saving procedure conducted commonly by the nurses at the prescription of the attending physician or the emergency physicians. It is generally a safe procedure if guidelines for processing and administering are carefully followed. Blood transfusion is an independent risk factor for morbidity and mortality and major complications arising from transfusion are generally rare. We present a case of a mild case of iatrogenic air embolism exacerbated by pressure infusion for a patient who had undergone an exploratory laparotomy for an iatrogenic fistula repair under epidural anesthesia.

On the microstructurally driven heterogeneous response of brain white matter to drug infusion pressure

Delivering therapeutic agents into the brain via convection-enhanced delivery (CED), a mechanically controlled infusion method, provides an efficient approach to bypass the blood–brain barrier and deliver drugs directly to the targeted focus in the brain. Mathematical methods based on Darcy’s law have been widely adopted to predict drug distribution in the brain to improve the accuracy and reduce the side effects of this technique. However, most of the current studies assume that the hydraulic permeability and porosity of brain tissue are homogeneous and constant during the infusion process, which is less accurate due to the deformability of the axonal structures and the extracellular matrix in brain white matter. To solve this problem, a multiscale model was established in this study, which takes into account the pressure-driven deformation of brain microstructure to quantify the change of local permeability and porosity. The simulation results were corroborated using experiments measuring hydraulic permeability in ovine brain samples. Results show that both hydraulic pressure and drug concentration in the brain would be significantly underestimated by classical Darcy’s law, thus highlighting the great importance of the present multiscale model in providing a better understanding of how drugs transport inside the brain and how brain tissue responds to the infusion pressure. This new method can assist the development of both new drugs for brain diseases and preoperative evaluation techniques for CED surgery, thus helping to improve the efficiency and precision of treatments for brain diseases.

Constant Pressure Convection-Enhanced Delivery Increases Volume Dispersed With Catheter Movement in Agarose.

Convection-enhanced delivery (CED) has been extensively studied for drug delivery to the brain due to its inherent ability to bypass the blood-brain barrier. Unfortunately, CED has also been shown to inadequately distribute therapeutic agents over a large enough targeted tissue volume to be clinically beneficial. In this study, we explore the use of constant pressure infusions in addition to controlled catheter movement as a means to increase volume dispersed (Vd) in an agarose gel brain tissue phantom. Constant flow rate and constant pressure infusions were conducted with a stationary catheter, a catheter retracting at a rate of 0.25 mm/min, and a catheter retracting at a rate of 0.5 mm/min. The 0.25 mm/min and 0.5 mm/min retracting constant pressure catheters resulted in significantly larger Vd compared to any other group, with a 105% increase and a 155% increase compared to the stationary constant flow rate catheter, respectively. These same constant pressure retracting infusions resulted in a 42% and 45% increase in Vd compared to their constant flow rate counterparts. Using constant pressure infusions coupled with controlled catheter movement appears to have a beneficial effect on Vd in agarose gel. Furthermore, constant pressure infusions reveal the fundamental limitation of flow-driven infusions in both controlled catheter movement protocols as well as in stationary protocols where maximum infusion volume can never be reliably obtained.

Effect Evaluation on Pressure Infusion Joint Combined with Cluster Nursing Intervention in Invasive Blood Pressure Monitoring of Critically Ill Patients

Effect Evaluation on Pressure Infusion Joint Combined with Cluster Nursing Intervention in Invasive Blood Pressure Monitoring of Critically Ill Patients

Intraosseus administration of an ultrasound contrast agent in a case of pediatric blunt abdominal trauma

Adding an ultrasound contrast agent to the Focused Assessment with Sonography in Trauma (FAST) exam can substantially improve the diagnostic accuracy of identifying solid organ injuries and rapidly identify significant organ lacerations and active intraperitoneal hemorrhage. The standard recommendations are to use a 20g peripheral IV for administration to prevent microbubble breakage associated with high infusion pressures. In time-critical trauma resuscitations however, rapid vascular access often necessitates the use of intraosseous catheters (IO). We describe the first use of IO access to successfully administer an ultrasound contrast agent in a critically injured 16 month-old toddler. The cFAST exam identified a liver laceration and provided superior diagnostic information compared the non-contrast abdominal CT obtained at an outside facility. • Adding an ultrasound contrast agent to the FAST exam can help to rapidly diagnose significant solid abdominal organ injuries. • Ultrasound contrast arrival times and organ opacification appear to be similar to the intravenous route. • A contrast-enhanced FAST exam (cFAST) can provide superior diagnostic information compared to an unenhanced abdominal CT.

Abstract No. 539 Retrospective review of pancreatic venous anatomy

To map the pancreatic venous anatomy as seen on triple-phase CT of the abdomen in preparation for Pancreatic Retrograde Venous Infusion (PRVI) Pressure Enabled Drug Delivery (PEDD) trials for locally advanced pancreatic ductal adenocarcinoma

Dynamic Pressure Measurements During Vitrectomy in a Model of the Eye.

PurposeTo accurately evaluate pressure changes during vitrectomy in a rigid model of the vitreous chamber and to test the efficiency of the EVA phacovitrectomy system (Dutch Ophthalmic Research Center) in terms of compensation of intraocular pressure variations.MethodsWe tested 23-, 25-, and 27-gauge double-blade vitreous cutters in both vented global pressure control and automatic infusion compensation (AIC) modes in a vitreous chamber model, mimicking the real surgical procedure. Balanced salt solution and artificial vitreous, similar to the real vitreous body, were used. We tested both standard-flow (SF) and high-flow (HF) infusion systems, varying the infusion pressure between 20 and 40 mm Hg. In each experiment, flow rate was also measured.ResultsPressure drop was rapidly and efficiently compensated when 23- and 25-gauge cutters were used in AIC mode, with infusion pressures ranging between 30 and 55 mm Hg. The 27-gauge cutter was less efficient in compensating pressure variations. Pressure fluctuations related to the high-frequency motion of the cutter blade were small compared to the overall pressure variations. The use of the HF infusion system resulted in larger flow rates and lower pressure changes compared to the SF infusion system.ConclusionsDespite the rigid material of the model, the present pressure measurements are in line with previous studies performed on porcine eye. The use of AIC mode compensates intraoperative pressure drops efficiently, with both 23- and 25-gauge cutters. The HF infusion system is more efficient than the SF infusion system.Translational RelevanceThe AIC infusion mode efficiently compensates intraoperative pressure drops, in both 23- and 25-gauge experimental vitrectomy. The HF infusion system resulted in larger flow rate and lower pressure changes.

Multi-objective optimization of diesel engine performance, vibration and emission parameters employing blends of biodiesel, hydrogen and cerium oxide nanoparticles with the aid of response surface methodology approach

Recent surges in crude oil prices have motivated researchers to find an alternative sustainable fuel called biodiesel from various inedible oils with lower carbo impact on the environment. The research is performed in diesel engine fuelled with blends of biodiesel coupled with cerium oxide nanoparticles and hydrogen content so as to optimize various factors which are responsible for performance, vibration and emission characteristics. Multi-objective optimization is achieved by employing RSM which also examines prime input parameters (engine load, nanoparticle concentration, compression ratio, hydrogen blend percentage and ignition pressure) responsible in varying engine characteristics. Henceforth, blends of Water Hyacinth can be successfully applied in diesel engine with lower environmental impact and enhanced cost effectiveness. Experimentation is performed on the central composite rotating design (CCRD) matrix with 5-level factor. Engine load was applied between 0 and 100%, NPC varied between 0 and 80 ppm, CR ranges between 17 and 19, hydrogen blend percentage varies between 0 and 40% and at a maximum injection pressure of 240 bar. Pareto-optimal conditions achieved for input conditions of 28.68% biofuel blend, 87.88 engine load, 80 ppm NPC, compression ratio of 19 and 194.54 bar infusion pressure were BTE, BSEC, NOx, UBHC and vibration reduction are 33.57%, 0.2550, 461.3002 ppm vol., and 28.08 ppm vol. And 22.21%, respectively.

Postmortem Retrograde Contrasted Infusion in Thoracic Duct Outflow: Imaging Effectiveness Analysis.

BackgroundThoracic duct (TD) anomaly can be quite variable and dangerous in surgical interventions in the neck region as there are numerous variations in its formation and topography. This highlights the importance of full knowledge about the TD and its anatomical variations. Thus, it is important to emphasize that the lack of anatomical-clinical knowledge or surgical skill during an intervention can significantly hamper successful results. The present study aimed to perform radiopaque contrast infusion into the TD of intact cadavers, either formalinized or refrigerated, to evaluate possible lymphatic architecture patterns via reverse lymphography.MethodologyTD dissection was performed on 13 cadaveric specimens. After isolating the lymphatic vessel, it was cannulated with an nº 4 urethral probe fixed with cordonnet cotton. Then, a 10 mL syringe was attached to the urethral probe and the radiopaque iodinated contrast was injected into the TD under constant and gradual manual pressure.ResultsTD outflow was detected on the posterior surface of the junction between the internal jugular and the left subclavian veins, either as direct outflow (in 10 cases) or as an arc (in three cases). Reverse contrast progression was impossible in each of the attempts, probably due to valvular resistance and lumen obliteration, which completely prevented pressure infusion into the thoracic and abdominal parts of the TD.ConclusionsWe emphasize the impracticality of obtaining postmortem radiopaque images via retrograde contrast injection into the TD in formalinized or refrigerated bodies.

Simultaneous characterization of preform expansion and permeability in vacuum assisted resin infusion

AbstractVacuum assisted resin infusion (VARI) is a composite manufacturing process, in which a fibrous reinforcement is laid out in a mold, and then sealed under a vacuum bag. The preform is compressed under vacuum and a liquid polymer resin is infused into the mold cavity. A characterization of compressibility and permeability is required to get accurate predictions of infusion times and thickness of final parts. A new experimental methodology is developed to simultaneously characterize the preform expansion and permeability of fibrous reinforcements during infusion. It is implemented in a one‐dimensional rectangular workbench by impregnating the preform with silicone oil. Pressure sensors measure the liquid pressure, and the reinforcement thickness is acquired by linear variable displacement transducers (LVDTs). The flow rate is also recorded with a scale. The expansion of the wetted reinforcement and permeability can be modeled by power laws as a function of pressure and fiber volume content, respectively. For isotropic preforms, a single experiment provides all the information needed to simulate the flow and predict the infusion time, the thickness and pressure. To validate this new characterization approach, the results of two infusions are successfully compared with numerical simulations.