Negative Pressure Assisted Microenvironment Surgical Hood: A Novel Cost-Effective Device to Minimize Aerosol Contamination During Neurosurgical Procedures in Times of COVID-19

Objective

Present guidelines on reducing aerosol generation during neurosurgical procedures are futile. The aim of this article was to describe a novel device to contain aerosol within a small localized environment around the operative field—the negative pressure assisted microenvironment surgical hood (NEPA-MESH).

Methods

This device can be assembled using easily available materials—steel wires, image intensifier cover, surgical drape, and three-dimensional–printed self-locking copolyester double hoops. Large-bore pipes in continuity with a high-volume suction apparatus create a constant negative pressure microenvironment around the operative field. The CEM DT-9880 particle counter was used to estimate particle concentration inside the NEPA-MESH during various stages of a neurosurgical procedure as well as outside. The NEPA-MESH was tested in different craniotomies and endoscopic procedures.

Results

Mean particle concentration inside the NEPA-MESH and outside during drilling in various procedures was calculated and compared using unpaired t test. Significant reduction in particle concentrations was recorded for particles sized 0.3 μm (t = 17.55, P < 0.0001), 0.5 μm (t = 11.39, P < 0.0001), 1 μm (t = 6.36, P = 0.0002), 2.5 μm (t = 2.04, P = 0.074), 5.0 μm (t = 7.026, P = 0.0008), and 10 μm (t = 4.39, P = 0.0023).

Conclusions

As definitive evidence demonstrating the presence of coronavirus disease 2019 (COVID-19) in aerosol particles is awaited, we describe a cost-effective strategy to reduce aerosol contamination. Significant reduction in particle concentrations was seen outside the NEPA-MESH compared with inside it during various stages of neurosurgical procedures.

Negative pressure wound therapy: device design, indications, and the evidence supporting its use

Introduction: Negative pressure wound therapy (NPWT) has become a mainstay in the armamentarium for wound care. Since the initial commercial vacuum-assisted closure device became available in 1995, subsequent research has confirmed the positive physiological effects of negative pressure on wound healing. Traditionally, NPWT has been used to improve healing of open nonsurgical wounds by secondary intention. However, the clinical applications of NPWT have significantly broadened, and now also include use in open surgical wounds, closed surgical incisions, and skin graft surgery. In addition, devices have evolved and now include functionality and features such as instillation, antimicrobial sponges, and portability.Areas covered: This article reviews the history, background, and physiology underlying NPWT, as well as the most commonly used devices. In addition, an evidence-based discussion of the current clinical applications of NPWT is presented, with a focus on those with high levels of evidence.Expert opinion: Future directions for device development include modifications to increase ease of use by patients and to allow its use in a broader array of anatomic areas. Lastly, more research with high levels of evidence is needed to better define the outcomes associated with NPWT, including in relation to specific clinical applications and cost.

Investigating the cause of hemolysis in patients supported by a pulsatile ventricular assist device

A survey conducted by Abiomed, Inc. revealed that 10 of 60 patients who received ventricular assistance via the AB5000 ventricular assist device (VAD) experienced hemolysis. The present study was conducted to investigate which factors influence hemolysis under pulsatile-flow VADs such as the AB5000. We compared the specificity of the AB5000 and its driving console with those of the NIPRO-VAD and VCT50χ under severe heart failure conditions using a mock circulatory system with a glycerol water solution. We used the mock circuit with bovine blood to confirm which pump conditions were most likely to cause hemolysis. In addition, we measured the shear velocity using particle image velocimetry by analyzing the seeding particle motion for both the AB5000 and NIPRO-VAD under the same conditions as those indicated in the initial experiment. Finally, we analyzed the correlation between negative pressure, exposure time, and hemolysis by continuously exposing fixed vacuum pressures for fixed times in a sealed device injected with bovine blood. Applying higher vacuum pressure to the AB5000 pump yielded a larger minimum inlet pressure and a longer exposure time when the negative pressure was under - 10 mmHg. The plasma-free hemoglobin increased as more negative pressure was driven into the AB5000 pump. Moreover, the negative pressure interacted with the exposure time, inducing hemolysis. This study revealed that negative pressure and exposure time were both associated with hemolysis.

Predictive factors of mortality in open abdomen for abdominal sepsis: a retrospective cohort study on 113 patients

Over the past few years, the open abdomen (OA) as a part of Damage Control Surgery (DCS) has been introduced as a surgical strategy with the intent to reduce the mortality of patients with severe abdominal sepsis. Aims of our study were to analyze the OA effects on patients with abdominal sepsis and identify predictive factors of mortality. Patients admitted to our institution with abdominal sepsis requiring OA from 2010 to 2019 were retrospectively analyzed. Primary outcomes were mortality, morbidity and definitive fascial closure (DFC). Comparison between groups was made via univariate and multivariate analyses. On 1474 patients operated for abdominal sepsis, 113 (7.6%) underwent OA. Male gender accounted for 52.2% of cases. Mean age was 68.1 ± 14.3 years. ASA score was > 2 in 87.9%. Mean BMI, APACHE II score and Mannheim Peritonitis Index were 26.4 ± 4.9, 15.3 ± 6.3, and 22.6 ± 7.3, respectively. A negative pressure wound system technique was used in 47% of the cases. Overall, mortality was 43.4%, morbidity 76.6%, and DFC rate was 97.8%. Entero-atmospheric fistula rate was 2.2%. At multivariate analysis, APACHE II score (OR 1.18; 95% CI 1.05–1.32; p = 0.005), Frailty Clinical Scale (OR 4.66; 95% CI 3.19–6.12; p < 0.0001) and ASA grade IV (OR 7.86; 95% CI 2.18–28.27; p = 0.002) were significantly associated with mortality. OA seems to be a safe and reliable treatment for critically ill patients with severe abdominal sepsis. Nonetheless, in these patients, co-morbidity and organ failure remain the major obstacles to a better prognosis.

Development of a valve type semi-closed extracorporeal circulation system

In Japan, perfusionists who work on other clinical tasks are involved in cardiopulmonary bypass. Moreover, the number of cases they can perform is limited. In view of this situation, valve type semi-closed extracorporeal circulation (VACC) was developed as a system that enables extracorporeal circulation (ECC) regardless of perfusionists’ experience. The VACC circuit is based on a conventional open-type ECC circuit. A safety valve is installed at the outlet of the reservoir. It is closed by lowering the reservoir pressure below the venous circuit pressure (Pv), thereby providing a closed-type ECC in which the reservoir is separated from the venous circuit (V-circuit). A closed-type ECC needs means to cope with negative pressure generated in the V-circuit and to remove air mixed in the V-circuit. Water experiments to verify the safety of the VACC were conducted. In experiments simulating low venous return, when the Pv dropped, the safety valve opened so that the V-circuit was connected to the reservoir, and the excessive negative pressure was relieved. In the VACC circuit, a bubble trap is installed in the V-circuit, and the air is degassed to the reservoir by a roller pump (D-pump). A water experiment was conducted to verify the principle of the constant degassing method using the D-pump. It verified that the blood storage volume could be maintained constant even if the D-pump is continuously driven. The VACC system provides handling of air mixed in the V-circuit and safety in the case of low venous return.

Negative pressure wound therapy in grade 1 and 2 diabetic foot ulcers: A randomized controlled study

BACKGROUND AND AIMS

Foot ulcers are one of the major causes of morbidity and mortality among diabetics in India. Early diagnosis and timely management is vital in preventing the progression of the disease which may require amputation. Conventional methods take a long time for healing. This study aims to compare negative pressure wound therapy (NPWT) and conventional saline dressings in diabetic foot ulcer (DFU) healing.

METHODS

This prospective randomized study was conducted in 45 patients with grade 1 and 2 DFUs. 22 patients in group A received NPWT and 23 patients in group B received saline dressings. The formation of granulation tissue, reduction in ulcer size, duration of hospital stay and time for complete healing of wounds were assessed.

RESULTS

The formation of granulation tissue (91.14 vs 52.61%, p < 0.001) and reduction in ulcer size (40.78 vs 21.18%, p = 0.008) at 14 days was significantly more in group A. The duration of hospital stay (15.68 vs 29.00 days, p < 0.001) and time for 100% coverage of the wound with granulation tissue (14.82 ± 7.30 vs 44.57 ± 7.11 days, p < 0.001) was significantly less in group A. Complete healing of wounds at 3 months was observed in 20 patients (90.9%) in group A and 6 patients (26.1%) in group B (p = 0.006).

CONCLUSION

In our study NPWT led to early reduction in ulcer size, more granulation tissue formation, shorter hospital stay and complete wound healing. In lower and middle income countries like India with high prevalence of DFUs, early recovery is a boon to the patients to resume their daily activities.

The utility of a novel vacuum-assisted foreign body extraction technique from wounds

Retained soft tissue foreign bodies following injuries are frequently seen in the Emergency and Plastic Surgery practice. The patients with such presentations require a watchful and detailed clinical assessment to overcome the anticipant possibility of missing them. However, the diagnosis based on the clinical evaluation is usually challenging and needs to be supported by imaging modalities that are suboptimal and may fail in identifying some types of foreign bodies. Owing to that, serious complications such as chronic pain, infection, and delayed wound healing can be faced that necessitate a prompt intervention to halt those detrimental consequences. The classical method of removal is a surgical exploration which is not free of risks. It can cause injuries to vital structures such as nerves and tendons if the foreign body is close to them, also it can be affected by the surgeon's experience and the foreign body's characteristics.

In light of that, we conducted a single-center study to understand the utility of a novel vacuum-assisted technique for foreign body removal. The technique is noninvasive and facilitates a real-time foreign body extraction using readily available materials. Twenty patients with 23 Foreign Bodies of various kinds, shapes, and sizes were recruited in our study by using a nonprobability convenient sampling method. Results demonstrated the ability of the described technique to extract 22 of them with no noticeable side effects. This study may encourage further trials adopting similar principles to promote the management of retained foreign bodies with fewer complications, and a potential of time and cost-saving.

Modeling the mechanics of elevated vacuum systems in prosthetic sockets

Elevated vacuum (EV) is suggested to improve suspension and limb volume management for lower limb prosthesis users. However, few guidelines have been established to facilitate configuration of EV sockets to ensure their safe and proper function. A benchtop model of an EV socket was created to study how prosthetic liner tensile elasticity, socket fit, and socket vacuum pressure affect liner displacement and subsequent pressure on the residual limb. A domed carbon fiber layup was used to represent an EV socket. Inserts were used to simulate various air gaps between the socket and liner. Various prosthetic liner samples were placed under the carbon fiber layup. Liner displacement and the corresponding pressure change underneath the liner were measured as vacuum was applied between the liner sample and socket wall. Tissue vacuum pressure increased linearly with socket vacuum pressure until the liner contacted the socket wall. Predicted tissue vacuum pressure matched well with experimental results. Findings suggest that the effect of vacuum pressure on the residual limb is primarily determined by air gap distance. The developed model may be used to assess effects of EV on residual limb tissues based on an individual's socket fit, liner characteristics, and applied vacuum. Understanding the physiological effects of EV on the residual limb could help practitioners avoid blister formation and improve EV implementation.

Choice and management of negative pressure drainage in anterior cervical surgery

BACKGROUND

Postoperative unobstructed drainage is an important measure for avoiding hematoma formation and preventing complications from anterior cervical surgery.

AIM

To discuss the characteristics and key points of clinical management of two types of commonly used negative pressure drainage systems in clinical settings.

METHODS

Two types of commonly used silica gel negative pressure drainage balls and a type of gastrointestinal decompression apparatus were fully emptied and then injected with different amounts of water and air. Following this, the negative pressure values of the three devices were measured. Meanwhile, we undertook a retrospective analysis of the clinical data of 1328 patients who had been treated with different negative pressure drainage apparatuses during their anterior cervical surgery in our department between January 2007 and January 2018.

RESULTS

As the amount of injected air or water increased, the negative pressure of the silica gel negative pressure drainage ball decreased rapidly, dropping to zero when 150 mL of water or air was injected. In contrast, the negative pressure of gastrointestinal decompression apparatus decreased slowly, maintaining an ideal value even when 300 mL of water or air was injected. And statistical analysis demonstrated that patients who had been treated with the gastrointestinal decompression apparatus were less likely to develop severe complications than those who had been treated with the silica gel negative pressure drainage ball (P < 0.05).

CONCLUSION

This study showed that the gastrointestinal decompression apparatus has the advantages of large suction capacity, long duration of continuous negative pressure, and good drainage effect, all of which are the favorable factors for the use of this apparatus for negative pressure drainage in anterior cervical surgery.

Infection Control in Dental Anesthesiology: A Time for Preliminary Reconsideration of Current Practices

Relegated to clinical afterthought, the topic of infection control has never taken center stage in our modern dental sedation and anesthesiology practices. Surgical and procedural masks, gloves, gowns, protective eyewear, and appropriate surgical attire have remained de rigueur in both fashion and custom for decades. However, the emergence of certain seminal events throughout health care history has driven mandated changes when practitioners, staff, patients, and the surrounding communities were exposed or put at risk of exposure to infectious disease. Hepatitis, human immunodeficiency virus, and now the global COVID-19 pandemic involving the novel coronavirus SARS-CoV-2, have forced us into rethinking our current practices. This review article will contextualize previous epidemics and their influence on infection control in dental settings, and it will explore the rapid evolution of current modifications to personal protective equipment and infection mitigation practices specific to sedation and anesthesia in dentistry.

Vacuum myofascial therapy device for non-specific neck pain. A single blind randomized clinical trial

OBJECTIVES

This study aimed to investigate the efficacy of a vacuum myofascial therapy device (VT) for improving pressure pain thresholds (PPTs), range of motion (ROM), neck pain-related disability, pain, and quality of life in patients with non-specific neck pain.

METHODS

A randomized controlled trial in which thirty-eight participants with non-specific neck pain (NP) were randomly assigned to either an experimental (VT) or a comparison physical therapy program (PTP) group. The VT group (n = 19) received five sessions of treatment with a vacuum myofascial therapy device while the PTP group (n = 19) received five sessions of massage, ultrasound therapy (US), and transcutaneous electric nerve stimulation (TENS) over two weeks. The outcome measures were the numerical pain rating scale (NPRS), range of motion, quality of life (SF-12), neck disability Index (NDI), and PPTs at the end of treatment and at one-month follow-up.

RESULTS

Although both groups experienced improvements in pain, neck disability, range of motion, and pressure pain, these only were statistically significant in the VT group. At one-month follow-up, the VT group still showed improvements in pain, neck disability, and range of motion.

DISCUSSION

Vacuum myofascial therapy applied with a device offers similar results to other vacuum-based techniques such as cupping therapy. Moreover, in this device the parameters are digitally controlled, which allows for the precise reproduction of treatment.

The challenges of urgent radical sigmoid colorectal cancer resection in a COVID-19 patient: A case report

INTRODUCTION

The COVID-19 pandemic presents a unique global health challenge further complicating surgical management of COVID-19 positive patients due to a lack of published literature.

CASE

Within we discuss a 48-year-old Chinese man, presenting with acute gastrointestinal obstruction due to sigmoid colonic mass. The patient was screened and tested positive for COVID 19 due to his employment in Wuhan, China at the COVID-19 pandemic epicenter. The patient was subsequently taken for open sigmoid colonic resection, however the case presented multiple challenges due to the patient's COVID-19 positive status.

DISCUSSION

The challenges of surgical management of COVID-19 positive patients exist are four-fold. First the unknown efficacy of pre-surgical risk stratification in COVID-19 positive patients, second the risk of aerosolized COVID-19 transmission during intubation for surgery, third the risk of fecal COVID-19 transmission to surgical staff during large bowel resection, and fourth the post-operative challenges of caring for COVID-19 positive patients.

CONCLUSION

Further research is needed into these topics, as well as the medical management of COVID-19 surgical patients.

Brown Adipocyte and Splenocyte Co-Culture Maintains Regulatory T Cell Subset in Intermittent Hypobaric Conditions

Background

Brown adipocytes have thermogenic characteristics in neonates and elicit anti-inflammatory responses. We postulated that thermogenic brown adipocytes produce distinctive intercellular effects in a hypobaric state. The purpose of this study is to analyze the correlation between brown adipocyte and regulatory T cell (T_reg) expression under intermittent hypobaric conditions.

Methods

Brown and white adipocytes were harvested from the interscapular and flank areas of C57BL6 mice, respectively. Adipocytes were cultured with syngeneic splenocytes after isolation and differentiation. Intermittent hypobaric conditions were generated using cyclic negative pressure application for 48 h in both groups of adipocytes. Expression levels of T_regs (CD4 + CD25 + Foxp3 + T cells), cytokines [tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10), and the programmed death-ligand 1 (PD-L1)] co-inhibitory ligand were examined.

Results

Splenocytes, cultured with brown and white adipocytes, exhibited comparable T_reg expression in a normobaric state. Under hypobaric conditions, brown adipocytes maintained a subset of T_regs. However, a decrease in T_regs was found in the white adipocyte group. TNF-α levels increased in both groups under hypobaric conditions. In the brown adipocyte group, anti-inflammatory IL-10 expression increased significantly; meanwhile, IL-10 expression decreased in the white adipocyte group. PD-L1 levels increased more significantly in brown adipocytes than in white adipocytes under hypobaric conditions.

Conclusion

Both brown and white adipocytes support T_reg expression when they are cultured with splenocytes. Of note, brown adipocytes maintained T_reg expression in intermittent hypobaric conditions. Anti-inflammatory cytokines and co-inhibitory ligands mediate the immunomodulatory effects of brown adipocytes under altered atmospheric conditions. Brown adipocytes showed the feasibility as a source of adjustment in physical stresses.

Is constant negative pressure for external drainage of the main pancreatic duct useful in preventing pancreatic fistula following pancreatoduodenectomy?

BACKGROUND

This study sought to investigate the utility of constant negative pressure for external drainage of the main pancreatic duct in preventing postoperative pancreatic fistula (POPF) after pancreatoduodenectomy.

METHODS

Only patients with soft pancreas were included. In the former period (July 2013 to May 2015), gravity dependent drainage was applied (gravity dependent drainage group), and in the latter period (June 2015 to November 2016), constant negative pressure drainage (negative pressure drainage group) was applied to the main pancreatic duct stent.

RESULTS

There were 37 patients in the gravity dependent drainage group and 39 patients in the negative pressure drainage group. Clinically relevant POPF occurred in 21 patients (56.8%) in the gravity dependent drainage group and 13 patients (33.3%) in the negative pressure drainage group (p = 0.040). The incidence rate of major complications (Clavien-Dindo grade > III) was significantly lower in the negative pressure drainage group (13.2%) compared to the gravity dependent drainage group (48.7%) (p = 0.001). In-hospital stay was also significantly shorter in the negative pressure drainage group compared to the gravity dependent drainage group (median 25 vs. 33 days, p = 0.024). Multivariate analysis demonstrated that the gravity dependent drainage was one of the independent risk factors for the incidence of POPF (odds ratio, 3.33; p = 0.032).

CONCLUSIONS

In patients with soft pancreas, the incidence rate of clinically relevant POPF may be reduced by applying constant negative pressure to the pancreatic duct stent. It also has a potential to reduce overall incidence of major complications and shorten in-hospital stay after pancreatoduodenectomy.

[Negative pressure pulmonary edema: report of case series and review of the literature]

BACKGROUND AND OBJECTIVES

Negative pressure pulmonary edema occurs by increased intrathoracic negative pressure following inspiration against obstructed upper airway. The pressure generated is transmitted to the pulmonary capillaries and exceeds the pressure of hydrostatic equilibrium, causing fluid extravasation into the pulmonary parenchyma and alveoli. In anesthesiology, common situations such as laryngospasm and upper airway obstruction can trigger this complication, which presents considerable morbidity and requires immediate diagnosis and propaedeutics. Upper airway patency, noninvasive ventilation with positive pressure, supplemental oxygen and, if necessary, reintubation with mechanical ventilation are the basis of therapy.

CASE REPORT

Case 1: Male, 52 years old, undergoing appendectomy under general anesthesia with orotracheal intubation, non-depolarizing neuromuscular blocker, reversed with anticholinesterase, presented with laryngospasm after extubation, followed by pulmonary edema. Case 2: Female, 23 years old, undergoing breast reduction under general anesthesia with orotracheal intubation, non-depolarizing neuromuscular blocker, reversed with anticholinesterase, presented with inspiration against closed glottis after extubation, was treated with non-invasive ventilation with positive pressure; after 1 hour, she had pulmonary edema. Case 3: Male, 44 years old, undergoing ureterolithotripsy under general anesthesia, without neuromuscular blocker, presented with laryngospasm after laryngeal mask removal evolving with pulmonary edema. Case 4: Male, 7 years old, undergoing crude fracture reduction under general anesthesia with orotracheal intubation, non-depolarizing neuromuscular blocker, presented with laryngospasm reversed with non-invasive ventilation with positive pressure after extubation, followed by pulmonary edema.

CONCLUSIONS

The anesthesiologists should prevent the patient from perform a forced inspiration against closed glottis, in addition to being able to recognize and treat cases of negative pressure pulmonary edema.

Devising negative pressure within intercuff space reduces microaspiration

Background

Microaspiration past the tracheal tube cuffs causes ventilator-associated pneumonia. The objective of the current study was to evaluate whether creating negative pressure between the tracheal double cuffs could block the fluid passage past the tracheal tube cuffs.

Methods

A new negative pressure system was devised between the double cuffs through a suction hole in the intercuff space. Blue-dyed water was instilled above the cuff at negative suction pressures of − 54, − 68, − 82, − 95, − 109, − 122, and − 136 cmH₂O, and the volume leaked was measured in an underlying water trap after 10 min. Leakage tests were also performed during positive pressure ventilation, and using higher-viscosity materials. The actual negative pressures delivered at the hole of double cuffs were obtained by placing microcatheter tip between the intercuff space and the artificial trachea.

Results

No leakage occurred past the double cuff at − 136 cmH₂O suction pressure at all tracheal tube cuff pressures. The volume leaked decreased significantly as suction pressure increased. When connected to a mechanical ventilator, no leakage was found at − 54 cmH₂suction pressure. Volume of the higher-viscosity materials (dynamic viscosity of 63–108 cP <cP> and 370–430 cP) leaked was small compared to that of normal saline (0.9–1.1 cP). The pressures measured in the intercuff space corresponded to 3.8–5.9% of those applied.

Conclusions

A new prototype double cuff with negative pressure in the intercuff space completely prevented water leakage. The negative pressure transmitted to the tracheal inner wall was a small percentage of that applied.

Effectiveness of irrigation strategies on the removal of the smear layer from root canal dentin

The aim of this study was to evaluate the removal of the smear layer by some commonly used (needle-and-syringe irrigation, sonic activation, ultrasonically activated irrigation) and new root canal irrigation strategies (negative pressure irrigation and polymer rotary file) using a novel approach by comparing pre- and post-experimental images. Prepared root canals (n = 50) were subjected to a split tooth model and divided into 5 groups (n = 10): (1) needle-and-syringe irrigation (control); (2) sonic activation (SA); (3) negative pressure irrigation with continuous warm activated irrigation and evacuation (CWA); (4) polymer finishing file (FF); (5) ultrasonically activated irrigation (UAI). Smear layer scores and percentage of open dentinal tubules (%ODT) were evaluated by 2 examiners before and after irrigation procedures, from the middle and apical thirds of the root canal, on scanning electron microscopic images. Data were analysed using Kruskal-Wallis and post hoc tests at P = 0.05. Needle-and-syringe irrigation (control) showed no significant difference (both smear score and %ODT) compared to the pre-experimental value (P > 0.05). All other groups showed lower smear scores and higher %ODT, compared to the control (P < 0.05). The lowest smear score and highest %ODT were observed in the CWA group, which was significantly different from all other groups (P < 0.05). SA group showed significantly higher smear scores and lower %ODT than FF or UAI (P < 0.05). CWA showed superior removal of smear layer in the middle and apical thirds of the root canal compared to the other irrigation strategies.

Novel cavitation fluid jet polishing process based on negative pressure effects

Traditional abrasive fluid jet polishing (FJP) is limited by its high-pressure equipment, unstable material removal rate, and applicability to ultra-smooth surfaces because of the evident air turbulence, fluid expansion, and a large polishing spot in high-pressure FJP. This paper presents a novel cavitation fluid jet polishing (CFJP) method and process based on FJP technology. It can implement high-efficiency polishing on small-scale surfaces in a low-pressure environment. CFJP uses the purposely designed polishing equipment with a sealed chamber, which can generate a cavitation effect in negative pressure environment. Moreover, the collapse of cavitation bubbles can spray out a high-energy microjet and shock wave to enhance the material removal. Its feasibility is verified through researching the flow behavior and the cavitation results of the negative pressure cavitation machining of pure water in reversing suction flow. The mechanism is analyzed through a computational fluid dynamics simulation. Thus, its cavitation and surface removal mechanisms in the vertical CFJP and inclined CFJP are studied. A series of polishing experiments on different materials and polishing parameters are conducted to validate its polishing performance compared with FJP. The maximum removal depth increases, and surface roughness gradually decreases with increasing negative outlet pressures. The surface becomes smooth with the increase of polishing time. The experimental results confirm that the CFJP process can realize a high material removal rate and smooth surface with low energy consumption in the low-pressure environment, together with compatible surface roughness to FJP.

Recent Advances on the Application of Negative Pressure External Volume Expansion in Breast Plastic Surgery

BACKGROUND

External volume expansion (EVE) has been effectively applied as an assistance to fat transplantation on breast plastic surgery. Many indicators and refinements have been made in clinical practice; meanwhile, the related mechanism and more optimized preclinical model also have been explored in experimental studies.

METHODS

A literature search was conducted using PubMed with the keywords: EVE, negative pressure, breast enlargement, breast augmentation, breast reconstruction, breast plastic surgery and breast aesthetic surgery. Studies dealing with the clinical and preclinical aspects of the subject and also in vitro experiments related to a certain period of negative pressure and adipose-derived cells were selected, and those only focused on negative pressure were excluded.

RESULTS

The indications, contraindications, complications and treatments of EVE in clinical practice were summarized. The experimental studies were mainly classified into two groups (mechanical and translational) according to their contents. Mechanical studies were further divided into inference experimental validation phase studies. For the experimental validation phase, EVE was verified to promote angiogenesis, while it still remained controversial whether it would enhance adipogenesis and cell proliferation.

CONCLUSION

Clinically, our experience is on the stage of exploration, and there is a lack of standardized guidelines on its clinical application. Experimentally, the previous studies showed some subtly different views on the functional mechanisms. However, it is not enough to regulate the clinical practice yet. Therefore, related basic studies and long-term clinical follow-up are needed.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

[Effect of intermittent negative pressure on matrix metalloproteinase 9 and transforming growth factor β of tendon-bone interface and joint fluid after reconstruction of anterior cruciate ligament in rabbits]

Objective: To study the effect of intermittent negative pressure on matrix metalloproteinase 9 (MMP)-9 and transforming growth factor β of tendon-bone interface and joint fluid after reconstruction of anterior cruciate ligament in rabbits. Methods: A total of twenty-four New Zealand white rabbits were randomly selected hind leg of negative group, contralateral hind leg as control.Reconstruction of the anterior cruciate ligament was done by autogenous semitendinosus of rabbit.Joint of the negative pressure side placed drainage tube connecting the micro-negative pressure aspirator, and maintained an intermittent, low-intensity negative pressure.Control side placed ordinary drainage tube.Drainage tube of both sides was pulled out at the same time after 5 days.After 6 weeks, joint fluid and femur-ligament-tibia complex were obtained for study of expression of MMP-9 and TGF-β in joint fluid and tendon-bone interface. Result: Twenty-three rabbits were included in the study because of one rabbit joint infections.Detection of joint fluid showed that MMP-9 content is significantly lower in negative group than that in the control group, and the difference is statistically significant [(8.9±1.3) pg/L vs (12.3±1.8) pg/L (P=0.002)]. TGF-β content is significantly higher in negative group in joint fluid than that in the control group, and the difference is statistically significant [(19.0±2.2) pg/L vs (15.2±1.4) pg/L (P=0.000)]. Study of immunohistochemistry in tendon-bone interface found that expression of MMP-9 is lower in negative pressure group than that in the control group, and the difference is statistically significant (P=0.000). TGF-β expression is significantly higher in negative group in tendon-bone interface than that in the control group, and the difference is statistically significant (P=0.000). Conclusion: Intermittent negative pressure may reduce content of MMP-9 in joint fluid and expression of MMP-9 in tendon-bone interface, increase content of TGF-β in joint fluid and expression of TGF-β in tendon-bone interface after reconstruction of anterior cruciate ligament in rabbits.

Vacuum assisted closure technique: a short review

The management of difficult to heal wounds has always been a cause of concern for the treating clinicians. There has been a tremendous increase in the number patients presenting with difficult to heal wounds. The conventional techniques have been in use since the long time for the management of these wounds, yet desired results are not achieved always. Thus a newer novel technique which might be useful in the difficult to heal wounds and delivering at par or better results as compared to the conventional techniques is the need of the hour.

Evaluation of YAP signaling in a rat tympanic membrane under a continuous negative pressure load and in human middle ear cholesteatoma

OBJECTIVES

Mechanotransduction plays an important role in cell-proliferative activities. Negative pressure in the middle ear is thought to be an important factor related to the etiology of acquired middle ear cholesteatoma. However, the correlation between negative pressure in the middle ear and the mechanism of middle ear cholesteatoma formation remains unclear. In this study, we investigated the expression of key molecules for mechanotransduction immunohistochemically.

METHODS

An immunohistochemical analysis was performed using anti-Wnt5a (a marker of alternative Wnt signaling), -Yes-associated protein (YAP) (a marker of mechanosensing) and -pYAP (phosphorylated YAP at Ser 127: inactivated YAP) antibody in the tympanic membrane (TM) under a negative pressure load and in human middle ear cholesteatoma tissues.

RESULTS

The number of Wnt5a-positive cells had increased and YAP nuclear translocation was observed in epithelial and mesenchymal cells in the pars flaccida (PF) of the TM under a negative-pressure load and in human middle ear cholesteatoma tissues.

CONCLUSIONS

We demonstrated that negative pressure in the middle ear might possibly induce cell proliferation PF of TM in response to mechanical force (mechanotransduction) through YAP nuclear translocation mediated by alternative Wnt signaling, thus affecting human middle ear cholesteatoma formation.

[Negative pressure pulmonary edema following a cholecystectomy - A case report]

Negative pressure pulmonary edema (NPPE) or post-obstructive pulmonary edema (POPE) is a rare but a life threatening respiratory situation. The most frequent cause of NPPE is a post anesthetic laryngospasm. Edema is developed after relief of upper airway obstruction. Its incidence is 0.1 % of general anesthesia with tracheal intubation. We report this clinical case of a 28-year-old woman, who developed dyspnea followed by acute respiratory distress with unilateral pulmonary edema after extubation following general anesthesia for cholecystectomy under celioscopy. After elimination of any other cause, context, clinical and radiological characteristics, and the favorable evolution under oxygen and furosemide made it possible for us to link this acute respiratory distress to a NPPE whose pathophysiological causes and mechanisms are discussed.