Application Of Negative Pressure Research Articles

Closed incision Negative Pressure Therapy (ciNPT): does depression affect underlying tissues?

Closed incision Negative Pressure Therapy (ciNPT) has become a widespread practice in recent years. Described benefits concern the rate of wound infection, based on the assumption that negative pressure spreads inside the wound removing collections and edema. The study aims to clarify this technical point, on which experimental scientific evidence is lacking in literature. In the experimental animal (newly sacrificed pig), the pressure was measured for hours at the bottom of three surgical abdominal wounds sutured by planes and dressed in negative pressure therapy commercial sets. The depression applied to the surface of the sutured wounds (ciNPT) is not transmitted to the underlying tissues. The blue dye deposited in the deep layer of the wounds didn't surface as an effect of ciNPT. The possible benefits deriving from the application of negative pressure on sutured wounds must depend on a different mechanism from the diffusion of depression in the wound planes and in the underlying tissues.

A bioreactor for studying negative pressure wound therapy on skin grafts.

Negative pressure wound therapy (NPWT) has become the prevailing standard of care for treating complex soft tissue wounds and is now being considered for use in alternative applications including improving skin graft take. While it is generally agreed that negative pressure leads to improved wound healing, universal consensus on its optimal application is not supported in the literature. We describe the design and validation of a bioreactor to determine the prospective benefits of NPWT on skin grafts and engineered skin substitutes (ESS). Clinically relevant pressures were applied, and the native human skin was able to withstand greater negative pressures than the engineered substitutes. Both skin types were cultured under static, flow‐only, and −75 mm Hg conditions for 3 days. While it remained intact, there was damage to the epidermal‐dermal junction in the ESS after application of negative pressure. The normal skin remained viable under all culture conditions. The engineered skin underwent apoptosis in the flow‐only group; however, the application of negative pressure reduced apoptosis. Vascular endothelial growth factor levels were significantly higher in the normal flow‐only group, 152.0 ± 75.1 pg/mg protein, than the other culture conditions, 81.6 ± 35.5 pg/mg for the static and 103.6 ± pg/mg for the negative pressure conditions. The engineered skin had a similar trend but the differences were not significant. This bioreactor design can be used to evaluate the impacts of NPWT on the anatomy and physiology of skin to improve outcomes in wounds after grafting with normal or engineered skin.

Intraocular pressure and choroidal thickness respond differently to lower body negative pressure during spaceflight.

Spaceflight-associated neuro-ocular syndrome (SANS) develops during long-duration (>1 mo) spaceflight presumably because of chronic exposure to a headward fluid shift that occurs in weightlessness. We aimed to determine whether reversing this headward fluid shift with acute application of lower body negative pressure (LBNP) can influence outcome measures at the eye. Intraocular pressure (IOP) and subfoveal choroidal thickness were therefore evaluated by tonometry and optical coherence tomography (OCT), respectively, in 14 International Space Station crewmembers before flight in the seated, supine, and 15° head-down tilt (HDT) postures and during spaceflight, without and with application of 25 mmHg LBNP. IOP in the preflight seated posture was 14.4 mmHg (95% CI, 13.5-15.2 mmHg), and spaceflight elevated this value by 1.3 mmHg (95% CI, 0.7-1.8 mmHg, P < 0.001). Acute exposure to LBNP during spaceflight reduced IOP to 14.2 mmHg (95% CI, 13.4-15.0 mmHg), which was equivalent to that of the seated posture (P > 0.99), indicating that venous fluid redistribution by LBNP can influence ocular outcome variables during spaceflight. Choroidal thickness during spaceflight (374 µm, 95% CI, 325-423 µm) increased by 35 µm (95% CI, 25-45 µm, P < 0.001), compared with the preflight seated posture (339 µm, 95% CI, 289-388 µm). Acute use of LBNP during spaceflight did not affect choroidal thickness (381 µm, 95% CI, 331-430 µm, P = 0.99). The finding that transmission of reduced venous pressure by LBNP did not decrease choroidal thickness suggests that engorgement of this tissue during spaceflight may reflect changes that are secondary to the chronic cerebral venous congestion associated with spaceflight.NEW & NOTEWORTHY Spaceflight induces a chronic headward fluid shift that is believed to underlie ocular changes observed in astronauts. The present study demonstrates, for the first time, that reversing this headward fluid shift via application of lower body negative pressure (LBNP) during spaceflight may alter the ocular venous system, as evidenced by a decrease in intraocular pressure. This finding indicates that LBNP has the potential to be an effective countermeasure against the headward fluid shift during spaceflight, which may then be beneficial in preventing or reversing associated ocular changes.

A Pilot Study of Negative Pressure Therapy with Autologous Skin Cell Suspensions in a Porcine Model

Negative pressure wound therapy (NPWT) is an option for securing meshed split thickness skin grafts (mSTSGs) after burn excision to optimize skin graft adherence. Recently, the use of autologous skin cell suspension (ASCS) has been approved for use in the treatment of burn injuries in conjunction with mSTSGs.To date, limited data exists regarding the impact of NPWT on healing outcomes when the cellular suspension is utilized. It was hypothesized that NPWT would not negatively impact wound healing of ASCS+mSTSG. A burn, excision, mSTSG, ASCS ± NPWT model was used. Two Duroc pigs were utilized in this experiment, each with 2 sets of paired burns. Four wounds received mSTSG+ASCS+NPWT through post-operative day 3, and 4 wounds received mSTSG+ACSC+ traditional ASCS dressings. Cellular viability was characterized prior to spraying. Percent re-epithelialization, graft-adherence, pigmentation, elasticity, and blood perfusion and blood vessel density were assessed at multiple time points through 2 weeks. All wounds healed within 14 days with minimal scar pathology and no significant differences in percent re-epithelialization between NPWT, and non-NPWT wounds were observed. Additionally, no differences were detected for pigmentation, perfusion, or blood vessel density. NPWT treated wounds had less graft loss and improved elasticity, with elasticity being statistically different. These data suggest the positive attributes of the cellular suspension delivered are retained following the application of negative pressure. Re-epithelialization, revascularization, and repigmentation are not adversely impacted. The use of NPWT may be considered as an option when using ASCS with mSTSGs for the treatment of full-thickness burns.

Novel imaging methods reveal positive impact of topical negative pressure application on tissue perfusion in an in vivo skin model.

The influence of topical negative pressure application (TNPA) on tissue perfusion still remains controversial. TNPA was applied for 30 minutes on intact skin of 21 healthy participants. Measurements of tissue oxygen saturation and tissue temperature as signs of tissue perfusion were performed before application of the TNPA, directly after removal of the TNPA and 5, 10, 15, 20, and 30 minutes after removal of the dressing using the near infrared imaging (NIRI) and a thermal imaging camera. Tissue oxygen saturation showed an increase from 67.7% before applying the TNPA to 76.1% directly after removal of TNPA, followed by a decrease of oxygen saturation 30 minutes after removal of TNPA. The measured temperature of the treated skin area increased from 32.1°C to 36.1°C after removal of TNPA with a consecutive decrease of the temperature 30 minutes after removal. TNPA resulted in both a higher tissue oxygen saturation and a higher skin temperature after 30 minutes compared to the beginning. TNPA increases both tissue oxygen saturation and skin temperature as sign of an increase of tissue perfusion. NIRI and thermal imaging proved to be useful for measuring changes in tissue perfusion.

A NEW SURGICAL TECHNIQUE FOR PREVENTION OF LEAKAGE AFTER DUODENAL REPAIRS

Background: Duodenal injuries, due to their retroperitoneal location, are a diagnostic challenge to the surgeon; for this reason, they are identified in a late stage, and thus associated with increased morbidity and mortality. The diagnosis of duodenal injury requires a high level of suspicion. Delayed diagnosis and management of these injuries results in increased morbidity and mortality rates. It must be remembered that the retroperitoneal location of the duodenum usually precludes early detection of injury by physical examination, which is characterised by minimal findings. Signs of defence, abdominal rigidity and absence of bowel sounds indicate intra-abdominal injury and lead to a surgical procedure. There are many different surgical procedures based on injury complexity, one of which is the tube duodenostomy technique. Despite the advances in surgical technique, duodenal lesions are still associated with high morbidity and mortality rates. Purpose: The purpose of this presentation is to describe a new surgical technique in the management of duodenal injuries. Surgical Technique: The technique was performed on a patient, presented with Crohn’s disease together with intestinal tuberculosis, in the management of duodenal injury secondary to duodenocolic fistula and abscess during the postoperative follow-up. The patient was operated on due to invagination, intra-abdominal abscess and general condition deterioration. The second operation was performed because of contrast extravasation from the duodenum. Especially the third part of the technique, application of negative pressure through a tube enterostomy in order to prevent the accumulation of secretions and pressure increase in the duodenum, minimized the intra-duodenal pressure and decreased the risk of anastomotic dehiscence and fistula formation (Figure 1). For this purpose, continuous negative aspiration was performed with an aspiration cannula extended through the enterostomy tube during the first 14 days. The patient was recovered without any complications. Conclusion: The authors concluded that this new technique of “pyloric exclusion, the repair of the mucosal layer of the primary wound in the duodenum with a stapler and of serosa with vicryl, minimizing intra-duodenal pressure by applying negative pressure with the enterostomy tube” can be considered to be an alternative solution for duodenal injuries.

Time‐Frequency Analysis of Hemodynamics Oscillations during Presyncopal Lower Body Negative Pressure (LBNP)

Introduction Greater low frequency (LF) oscillations (~0.1 Hz) in mean arterial pressure (MAP) and cerebral blood flow (indexed by middle cerebral artery velocity; MCAv) have been associated with higher tolerance to central hypovolemia. As the fast Fourier transform approach was used in these prior studies, measuring exact timing of oscillatory amplitude was not possible. In the present study, the continuous wavelet transform was used for time localization and measurement of the magnitude of LF oscillations during application of lower body negative pressure (LBNP) to presyncope to reduce cerebral perfusion. We hypothesized that the magnitude of LF oscillations in MAP and MCAv would be higher in subjects with greater tolerance to this stress. We also hypothesized that the time of instantaneous maximum magnitude of LF oscillations would be further from baseline for high tolerant subjects. Methods 31 healthy human subjects (14 F: 17 M; 25.1 ± 3.0 y) underwent a stepwise LBNP protocol to presyncope. Subjects were classified as high tolerant (HT) if they completed the -60 mmHg stage of LBNP, and low tolerant (LT) if they did not. Continuous beat-to-beat MAP and mean MCAv were recorded. The continuous wavelet transform was used to extract magnitude of oscillations within the LF range (0.07-0.15 Hz) over time for both MAP and mean MCAv. The instantaneous maximum magnitude of LF oscillations was then extracted. Pearson's correlation was calculated for instantaneous LF magnitude of MAP and mean MCAv versus presyncopal time. A t-test was then used to compare magnitude and relative time of LF oscillations between HT and LT subjects. Results The maximum magnitude of MAP LF oscillations was positively correlated with presyncopal time (R = 0.39, P = 0.03). The maximum magnitude of MCAv LF oscillations, however, was not correlated with presyncopal time (R = -0.03, P = 0.86). When assessing HT and LT subjects, no differences were observed for maximum magnitude of LF oscillations in MAP (HT 4.3 ± 1.0, LT 3.7 ± 1.2, P=0.15) or MCAv (HT 3.1 ± 0.9, LT 3.1 ± 0.7, P=0.91). Time to maximum magnitude of LF oscillations was greater in high tolerant subjects for both MAP (HT 1384.5 ± 329.6 s, LT 798.6 ± 416.8 s, P<0.01) and MCAv (HT 1064.3 ± 431.6 s, LT 662.4 ± 380.1 s, P=0.01). When expressing the time of maximum amplitude as a percent of presyncopal time, the average time in all subjects for MAP was 73.6 ± 22.0 % and 59.6 ± 26.1 % for MCAv, and there were no differences between tolerance groups in either MAP (HT 79.5 ± 14.0 %, LT 67.4 ± 27.3 %, P=0.14) or MCAv (HT 61.8 ± 24.8 %, LT 57.3 ± 28.1 %, P=0.64). Conclusions Using wavelet analysis, only the maximum magnitude of MAP LF oscillations was modestly correlated to presyncopal time. Contrary to previous measures using fast Fourier transform, there was no difference in instantaneous maximum magnitude of oscillations in MAP and mean MCAv between high and low tolerant subjects indicating that both groups could mount similar responses. Interestingly, the relative timing of maximum magnitude of oscillations in MAP and MCAv was no different between tolerance groups.

Role of Closed Incision Negative Pressure Wound Therapy in Skin Grafting

Surgical site infection (SSI) results in substantial morbidity and costs. Various guidelines are there to reduce the incidence of SSI. Recently application of negative pressure to a surgically closed wound has also emerged as a way of preventing this complication. The commercially available devises for this are usually too costly and preclude its uses in developing countries. In this article we share our experience of using NPWT in cost effective manner in case of skin graft donor site.

Short-term Evaluation of Negative Pressure Applied by the Multi-Pressure Dial System to Lower Nocturnal IOP: A Prospective, Controlled, Intra-subject Study.

IntroductionThe purpose of this study was to investigate the short-term safety and feasibility of negative pressure application by the Multi-Pressure Dial (MPD) System to lower nocturnal intraocular pressure (IOP) in subjects with open-angle glaucoma (OAG).MethodsA prospective, controlled, intra-subject study of 22 eyes from 11 subjects at a single site was performed. All subjects had a history of OAG and were currently using a topical prostaglandin. For each subject, the eye with the highest IOP in the supine position was selected as the treatment eye (TE) and the contralateral eye served as the control eye (CE). The negative pressure for the TE was set to 60% of the baseline IOP value with no negative pressure in the CE. IOP measurements were collected at three prespecified time points overnight in the supine position with active negative pressure. The primary outcome measure was mean IOP with the application of negative pressure.ResultsAt the three overnight time points, the mean (± standard deviation) baseline IOP prior to negative pressure application was 22.2 ± 2.5 mmHg in the TE and 21.8 ± 2.5 mmHg in the CE. With the application of 60% negative pressure to the TE and no active negative pressure to the CE, the mean IOP was 14.2 ± 2.2 and 19.5 ± 2.4 mmHg, respectively. The mean percentage IOP reduction in the TE was 35% (p < 0.001). There were two minor adverse events, both unrelated to device wear, and there were no IOP spikes ≥ 10 mmHg.ConclusionThe MPD can safely and effectively lower nocturnal IOP in the supine position. The MPD holds promise as a potential new, non-invasive treatment option for the control of nocturnal IOP.

Mechanical stimulation is a key component in the development of pericellular matrix around human chondrocytes

Purpose: Articular cartilage within the joint experience multi-directional mechanical stimulation. These stimuli are transferred to the chondrocytes through the pericellular matrix, a small shell surrounding the cells. The signal is then translated by the cell, which subsequently responds by releasing catabolic or anabolic markers. Our aim was to be able to determine if, depending on the mechanical stimulus applied onto the chondrocytes, there would be a variation in extracellular matrix production. To address this, we used our cartilage-on-chip and studied the effects of mechanical stimulation on human articular chondrocytes. The cartilage-on-chip system includes a 3D cell-hydrogel compartment, a perfusion channel to provide nutrients and a mechanical actuation unit. The mechanical actuation unit, which is separated from the rest of the system by a thin elastic polydimethylsiloxane membrane, comprises 3 individually addressable chambers were positive or negative pressure can be applied (Fig. 1). We report here how different mechanical stimuli: 1) affect IL-6 cytokine production; and 2) the chondrocyte’s phenotype compared to static conditions; 3) influence the directionality in extracellular matrix deposition; 4) stimulate pericellular matrix formation, and; 5) differentially affect overall protein expression. Methods: The cartilage-on-chip was fabricated using soft-lithography with polydimethylsiloxane. Application of positive and/or negative pressure resulted in different sets of stimulations onto the 3D hydrogel (compression or compression & shear strain). Low melting temperature agarose (2% w/v) was used to embed human primary chondrocytes (hCHs), which were cultured in the platform for one day with proliferation medium followed by chondrocyte differentiation medium. First, the cell-laden constructs were stimulated for 7 days (1 h a day at 1 Hz) with either compression, or compression and shear strain (wave form) or without mechanical stimuli. Medium was collected from the device at day 1, 2, 3, 5 and 7 and IL-6 concentration quantified using enhanced SPRi. qPCR was performed at day 7 for Collagen type I and type II. Next, cell-laden hydrogels were cultured for 7 days in static condition and subsequently stimulated for 7 days with the two aforementioned mechanical actuation patterns, or in static conditions for a total of 14 days. Samples were fixed and stained for aggrecan, collagen type II and collagen type VI. Results: The expression of COL2A1 mRNA was higher in the mechanically stimulated samples in particular when using a combination of compression and shear strain. Interestingly, COL1A1 mRNA expression was inversely correlated with the COL2A1 mRNA with highest expression in the static conditions. Consequently, these results suggest the involvement of mechanical stimulation on the transition of human chondrocytes towards a more hyaline like cartilage phenotype. IL-6 secretion decreased over time with no detectable signal at day 7 for the static conditions indicating chondrocyte adaptation to the 3D environment. Moreover, IL-6 was higher in the constructs exposed to mechanical stimuli, indicating a role of mechanical stimulation in IL-6 production. Aggrecan, collagen type II and collagen type VI immunostaining revealed higher pericellular matrix production in dynamic conditions. The pericellular matrix formed was mainly present in the direction of the mechanical stimulation suggesting cell adaptation to the applied stimuli (Fig. 3). Furthermore, the combination of compression and shear strain additionally enhanced both aggrecan and collagen production. Conclusions: Our cartilage-on-a-chip platform allows exposure of hydrogel embedded chondrocytes to multi-modal mechanical stimuli. Mechanical actuation supported the creation of a pericellular matrix surrounding the cells. Here, chondrocytes responded differently both at the gene and protein levels depending on the stimuli applied. Interestingly, chondrocytes produced their matrix in the direction of the stimuli suggesting a cell adaptation or “self-protection” mechanism. We are currently investigating if, by applying different biochemical stimuli, it is possible to influence the composition of the pericellular matrix.View Large Image Figure ViewerDownload Hi-res image Download (PPT)View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Pressure effect on band inversion in AECd2As2 (AE=Ca, Sr, Ba)

Recent studies have predicted that magnetic EuCd2As2 can host several different topological states depending on its magnetic order, including a single pair of Weyl points. Here we report on the bulk properties and band inversion induced by pressure in the non-magnetic analogs AECd2As2 (AE = Ca, Sr, Ba) as studied with density functional theory calculations. Under ambient pressure we find these compounds are narrow band gap semiconductors, in agreement with experiment. The size of the band gap is dictated by both the increasing ionicity across the AE series which tends to increase the band gap, as well as the larger nearest neighbor Cd-As distance from increasing atomic size which can decrease the band gap because the conduction band edge is an anti-bonding state derived mostly from Cd 5s orbitals. The combination of these two competing effects results in a non-monotonic change of the band gap size across the AE series with SrCd2As2 having the smallest band gap among the three compounds. The application of negative pressure reduces this band gap and causes the band inversion between the Cd 5s and As 4p orbitals along the ${\Gamma}$-A direction to induce a pair of Dirac points. The topological nature of the Dirac points is then confirmed by finding the closed Fermi arcs on the (10-10) surface.

Application of negative tissue interstitial pressure improves functional capillary density after hemorrhagic shock in the absence of volume resuscitation.

Microvascular fluid exchange is primarily dependent on Starling forces and both the active and passive myogenic response of arterioles and post‐capillary venules. Arterioles are classically considered resistance vessels, while venules are considered capacitance vessels with high distensibility and low tonic sympathetic stimulation at rest. However, few studies have investigated the effects of modulating interstitial hydrostatic pressure, particularly in the context of hemorrhagic shock. The objective of this study was to investigate the mechanics of arterioles and functional capillary density (FCD) during application of negative tissue interstitial pressure after 40% total blood volume hemorrhagic shock. In this study, we characterized systemic and microcirculatory hemodynamic parameters, including FCD, in hamsters instrumented with a dorsal window chamber and a custom‐designed negative pressure application device via intravital microscopy. In large arterioles, application of negative pressure after hemorrhagic shock resulted in a 13 ± 11% decrease in flow compared with only a 7 ± 9% decrease in flow after hemorrhagic shock alone after 90 minutes. In post‐capillary venules, however, application of negative pressure after hemorrhagic shock resulted in a 31 ± 4% decrease in flow compared with only an 8 ± 5% decrease in flow after hemorrhagic shock alone after 90 minutes. Normalized FCD was observed to significantly improve after application of negative pressure after hemorrhagic shock (0.66 ± 0.02) compared to hemorrhagic shock without application of negative pressure (0.50 ± 0.04). Our study demonstrates that application of negative pressure acutely improves FCD during hemorrhagic shock, though it does not normalize FCD. These results suggest that by increasing the hydrostatic pressure gradient between the microvasculature and interstitium, microvascular perfusion can be transiently restored in the absence of volume resuscitation. This study has significant clinical implications, particularly in negative pressure wound therapy, and offers an alternative mechanism to improve microvascular perfusion during hypovolemic shock.

Exovent: a study of a new negative-pressure ventilatory support device in healthy adults.

Negative-pressure ventilation may have several advantages compared with positive-pressure ventilation. Negative-pressure ventilation simulates natural lung movements, does not require tracheal intubation and may reduce the incidence of barotrauma and adverse cardiovascular events. A group of engineers, doctors and nurses designed and bench-tested the Exovent, a new, lightweight, torso-only, negative-pressure ventilatory support system. We aimed to test the comfort, nursing acceptability and ventilatory support capabilities of the Exovent in healthy adult volunteers. We measured the effect of continuous negative extra-thoracic pressure on functional reserve capacity and the efficacy of ventilation produced by a combination of negative-pressure ventilation and negative end-expiratory pressure. Six members of the development team volunteered to test the device. The application of continuous negative extra-thoracic pressure did not change tidal volumes from baseline levels; however, functional reserve capacity increased by a mean (SD) of 1.1 (0.05) ml.kg-1 .cmH2 O-1 (p=0.0002). The combination of negative-pressure ventilation and negative end-expiratory pressure produced effective ventilation, with the resting tidal volume being exceeded by the application of -4 cmH2 O of extra-thoracic negative pressure. All the volunteers found the experience comfortable and none had ventilator dysynchrony. The Exovent allowed good nursing and monitoring access and was comfortable in both the semi-recumbent and prone positions. The Exovent delivered effective continuous negative extra-thoracic pressure and negative-pressure ventilation plus negative end-expiratory pressure to healthy adults. Further trials are needed to investigate the clinical utility of the device.

负压封闭引流(VSD)联合间断快速冲洗技术在下肢开放性骨折合并软组织缺损中的应用研究

负压封闭引流(VSD)联合间断快速冲洗技术在下肢开放性骨折合并软组织缺损中的应用研究

The Role of Negative Pressure Wound Therapy with Instillation and Dwell Time in the Preparation of Wound Bed

Introduction Although the negative pressure wound therapy (NPWT) is a time tested method of wound preparation, the role of NPWT with instillation and dwell time (NPWTi-d) in decreasing the downtime of wound preparation needs to be evaluated. Objective The objective of this study is assess the role of NPWTi-d in wound bed preparation. Materials and Methods This study was conducted in a tertiary care center, after getting informed consent and ethical clearance. NPWTi-d was done on a 36-years-old female with no known co-morbidities admitted with infected raw area over the right below knee amputation stump and exposed bone who was not responding well to conventional wound dressing. NPWT was applied with the help of sterile polyurethane sponge and two tubes. The antimicrobial solution used was ionic silver solution, just enough to wet the sponge completely and up to the point when the transparent occlusive covering begins to lift. Negative pressure was applied at 125 mmHg. The wound was bathed with ionic silver solution and it was allowed to stay in the wound for 10-minutes, after every 2-hours of negative pressure application. This was continued for 1-week. The dressing was opened at the end of 1-week, wound irrigated with normal saline, exudate swabs for culture taken and debrided, following which fresh NPWTi-d was applied. This was repeated for the next 3-weeks. Result By the end of third week, the wound became clean, fully covered with healthy granulation and the wound bed was ready to undergo the definitive wound cover procedure.

Acute purulent widespread peritonitis: conceptual aspects of modern surgical tactics

Background. The priority areas of the problem of acute widespread peritonitis (AWP) include the standardization of terminology and classification, assessment of the severity of the process, control of the infection source and correction of pathological intra-abdominal syndromes.&#x0D; Objective. To outline the conceptual aspects of AWP surgical treatment based on consensus guidelines and own research.&#x0D; Materials and methods. The study involved 371 patients with AWP. Patients underwent the necessary clinical, laboratory, biochemical, bacteriological, radiological, instrumental and pathomorphological studies.&#x0D; Results and discussion. To assess the severity of the disease one should assess the general clinical condition of the patient, the source and the site of infection, the presence or absence of organ or multiorgan dysfunction, the characteristics of the pathogen. The assessment of the clinical condition takes into account the patient’s age, physiological status and comorbid diseases, the general scales ASA, SOFA, APACHE, Marshall and peritonitis-specific scales (Mannheim Peritonitis Index, Peritonitis Index Altona). When determining the infection source, it is advisable to determine whether the process is provoked by damage to the upper or lower segment of the gastrointestinal tract. The most common causes of AWP in the own study were acute appendicitis (23 %), perforated gastric ulcer (21 %), acute pancreatitis and pancreatic necrosis (18 %). Acute cholecystitis, intestinal perforation, and anastomosis failure were somewhat less common. Suboperative measures during AWP surgery include detection and assessment of the source of the pathological process, elimination of the detected changes, lavage and adequate drainage of the abdominal cavity, correction of intra-abdominal pathological syndromes, clarification of the feasibility of programmed relaparotomy. Dekasan (“Yuria-Pharm”) is used for lavage. It is a local antiseptic, effective against gram-positive and gram-negative bacteria, viruses, and fungi. Dekasan is a surfactant that removes fibrin, pus, colonies of microorganisms and blood clots. According to V.V. Boiko et al. (2012), abdominal lavage with the help of Dekasan reduces postoperative mortality by almost 9 %, and the frequency of secondary purulent complications – by 16.5 %. Pathological intra-abdominal syndromes that need correction include abdominal compartment syndrome (ACS), intestinal insufficiency, and the excessive colonization of the proximal small intestine by pathological microflora. Prolonged tubal decompression of the small intestine, hyperbaric oxygenation, VAC-therapy, and application of negative pressure are used to decrease intra-abdominal hypertension in ACS. Tube techniques used in AWP include enteral lavage, enterosorption, selective pharmacological decontamination, and intraluminal transtubal electrophoresis. It is advisable to introduce enteral nutrition early. For additional detoxification and correction of water-electrolyte balance, low-volume infusion therapy with hyperosmolar solutions (Reosorbilact, “Yuria-Pharm”) is used. Reosorbilact contains sorbitol, sodium lactate and the necessary ions.&#x0D; Conclusions. 1. Modern approaches to solving the problem of AWP should be based on modern terminological and classification principles and provide an understanding of the content of surgery and the validity of antibiotic therapy. 2. Control of the source of peritonitis includes its complete elimination, lavage and drainage of the abdominal cavity, ensuring the decompression of the digestive tract with the implementation of a tubal program of measures. 3. Antibiotic therapy and infusion therapy are the important components of treatment. 4. The implementation of these statements will increase the effectiveness of AWP treatment.

Fabrication of Glass Micropipette Device Using Reflow Processes and Its Integration With Microfluidic Channels for Patch Clamp Recording of Cell

This paper presents a borosilicate glass micropipette device that has a high-aspect-ratio pore for patch clamp recording applications. The device was fabricated by carrying out glass reflow processes on a silicon substrate. The shape of the micropipette was determined by the width and thickness of the reflowed glass structure, which matches well with the rounded tip of a conventional glass pipette. The diameter of the micropipette pore was first defined by deep reactive ion etching (DRIE) of a silicon pillar, which was positioned at the center of the glass structure. Then, the silicon pillar was removed, and the pore diameter was additionally reduced to the submicron scale by depositing a parylene-C film. The fabricated device was integrated with microfluidic channels for patch clamp recording experiments: microfluidic PDMS layers were assembled on the top and bottom surfaces of the micropipette chip for the medium exchange and the application of negative pressure, respectively. The quality of seal between a cerebral cortex cell of a rat and the glass micropipette was characterized by the amplitude of the current produced by an applied voltage pulse. A negative pressure applied through the bottom microfluidic channel pulled down the cell and increased the seal resistance from 9.82 $\text{M}\Omega $ to 2.06 $\text{G}\Omega $ . This indicates that the gigaseal was successfully formed around the micropipette pore. In addition, the action potentials of the patched cortical neuron were recorded using the fabricated device.

Evaluation of the IOP-Lowering Effect of a Multi-Pressure Dial at Different Negative Pressure Settings.

PurposeTo evaluate the intraocular pressure (IOP)-lowering effect of a multi-pressure dial (MPD) at targeted negative pressure settings.MethodsProspective, intrasubject controlled study of 65 healthy subjects randomized to receive no negative pressure for 60 minutes or negative pressure application at designated levels of 25%, 50%, and 75% of baseline IOP for 20 minutes each. The main outcome measure was mean IOP with application of negative pressure.ResultsIn the study eye group, from a baseline IOP of 15.8 ± 3.6 mm Hg, the mean IOP was 13.5 ± 3.4, 11.5 ± 3.1, and 10.2 ± 2.7 mm Hg with negative pressure settings of 25%, 50% and 75%, respectively. In the control eye group, from a baseline IOP of 15.5 ± 3.0 mm Hg, the mean IOP values at the same time points, without negative pressure, were 15.6 ± 3.0, 15.5 ± 2.5 and 15.3 ± 2.4 mm Hg. The difference between the mean IOPs of the two groups was significantly different at all negative pressure settings (P < 0.001) in comparison with baseline. There was one minor adverse event, a corneal abrasion, that was unrelated to device wear.ConclusionsNegative pressure application to the periocular space with a multi-pressure dial can produce titratable IOP reduction while the device is worn with active negative pressure. To our knowledge, this technology represents the first nonpharmacologic, nonlaser, nonsurgical method for IOP reduction.Translational RelevanceThis represents the first study demonstrating the IOP-lowering ability of the multi-pressure dial, a device that uses a novel IOP-lowering strategy by delivering negative pressure to the periocular region.

Prophylactic Single-use Negative Pressure Dressing in Closed Surgical Wounds After Incisional Hernia Repair: A Randomized, Controlled Trial.

A randomized controlled trial (RCT) was undertaken to evaluate whether the prophylactic application of a specific single-use negative pressure (sNPWT) dressing on closed surgical incisions after incisional hernia (IH) repair decreases the risk of surgical site occurrences (SSOs) and the length of stay. The sNPWT dressings have been associated to several advantages like cost savings and prevention of SSOs like seroma, hematoma, dehiscence, or wound infection (SSI) in closed surgical incisions. But this beneficious effect has not been previously studied in cases of close wounds after abdominal wall hernia repairs. An RCT was undertaken between May 2017 and January 2020 (ClinicalTrials.gov registration number NCT03576222). Participating patients, with IH type W2 or W3 according to European Hernia Society classification, were randomly assigned to receive intraoperatively either the sNPWT (PICO)(72 patients) or a conventional dressing at the end of the hernia repair (74 patients). The primary endpoint was the development of SSOs during the first 30 days after hernia repair. The secondary endpoint included length of hospital stay. Statistical analysis was performed using IBM SPSS Statistics Version 23.0. At 30 days postoperatively, there was significatively higher incidence of SSOs in the control group compared to the treatment group (29.8% vs 16.6%, P < 0.042). There was no SSI in the treatment group and 6 cases in the control group (0% vs 8%, P < 0.002). No significant differences regarding seroma, hematoma, wound dehiscence, and length of stay were observed between the groups. The use of prophylactic sNPWT PICO dressing for closed surgical incisions following IH repair reduces significatively the overall incidence of SSOs and the SSI at 30 days postoperatively.

Coagulation Changes during Central Hypovolemia across Seasons.

Lower body negative pressure (LBNP) application simulates hemorrhage. We investigated how seasons affect coagulation values at rest and during LBNP. Healthy participants were tested in cold (November–April) and warm (May–October) months. Following a 30-min supine period, LBNP was started at −10 mmHg and increased by −10 mmHg every five minutes until a maximum of −40 mmHg. Recovery was for 10 min. Blood was collected at baseline, end of LBNP, and end of recovery. Hemostatic profiling included standard coagulation tests, calibrated automated thrombogram, thrombelastometry, impedance aggregometry, and thrombin formation markers. Seven men (25.0 ± 3.6 years, 79.7 ± 7.8 kg weight, 182.4 ± 3.3 cm height, and 23.8 ± 2.3 kg/m2 BMI) and six women (25.0 ± 2.4 years, 61.0 ± 8.4 kg weight, 167 ± 4.7 cm height, and 21.8 ± 2.4 kg/m2 BMI) participated. Baseline levels of prothrombin (FII), tissue factor (TF) and markers for thrombin generation F1+2 and the thrombin/antithrombin complex (TAT) were higher during summer. Factor VIII, prothrombin fragment 1+2 (F1+2), TAT and the coagulation time showed significant increases during LBNP in both seasons. Some calibrated automated thrombography variables (Calibrated automated thrombography (CAT): lag, time to peak (ttPeak), peak) shifted in a procoagulant direction during LBNP in summer. Red blood cell counts (RBC), hemoglobin and white blood cell counts (WBC) decreased during LBNP. LBNP application reduced prothrombin time in winter and activated partial thromboplastin time in summer. Greater levels of FII, TF, F1+2, and TAT—a more pronounced LBNP-induced procoagulative effect, especially in CAT parameters (lag time (LT), Peak, ttPeak, Velindex)—were seen in summer. These results could have substantial medical implications.