Comparison of negative pressure wound therapy against normal dressing after vascular surgeries for inguinal wounds: A systematic review and meta-analysis

Background

Negative Pressure Wound Therapy (NPWT) is a therapeutic technique of applying sub-atmospheric pressure to a wound to reduce inflammation, manage exudate, and promote the formation of granulation tissue. It aims to optimise the natural physiological processes of wound healing for more effective recovery, and NPWT has emerged as a promising alternative to traditional dressings.

Methods

The protocol followed in the study was prospectively registered. Appropriate search terms and Boolean operators were used to search electronic databases for relevant articles. Screening of articles was performed, and data extraction was done. The effect measure was chosen according to the nature of the variable, and the effect model was chosen as per heterogeneity. Forest plot was used to give visual feedback.

Results

This study included 11 randomized controlled trials (13 publications) with a total of 1310 patients (1497 inguinal wounds). The NPWT group had lesser odds of developing surgical site infection (OR: 0.40; 95 % CI: 0.29-0.54; n = 1491; I2 = 20 %; p-value ≤0.00001) and lesser odds of needing surgical wound revision (OR: 0.48; 95 % CI: 0.26-0.91; n = 856; I2 = 0 %; p-value = 0.02) as compared to the normal dressing group. No significant difference was observed in duration of hospital stay, cost of care, wound healing time, or other complications.

Conclusion

NPWT application in inguinal wounds significantly reduces the surgical site infection and the need for wound revision in patients who have undergone vascular surgery.

Pulsed negative pressure myofascial vacuum therapy and percutaneous electrolysis in the treatment of lateral epicondylalgia: A single-blind randomized controlled trial

BACKGROUND

Lateral Epicondylalgia (LE) represents one of the most common injuries of the upper limb. It is necessary to find effective treatments that reduce pain and increase functionality.

PURPOSE

To determine the effects of an integrated intervention of Pulsed Negative Pressure Myofascial Vacuum Therapy (VT), Percutaneous Electrolysis (PE) and eccentric exercise (EE) in the treatment of LE compared versus Manual Therapy soft tissue mobilization (MT) and Ultrasound therapy (US) and EE.

STUDY DESIGN

Single-blind randomized controlled trial.

METHODS

Forty participants, with unilateral LE, were randomly divided into two groups: VT + PE + EE group (n = 20) and MT + US + EE group (n = 20). The VT + PE + EE group received one weekly session for four weeks and a regimen of EE daily at-home, and the MT + US + EE group received 10 sessions over a period of two weeks and a regimen of EE daily at-home. Numerical pain rating scale (NPRS), range of motion (ROM) pressure pain threshold (PPT) and function (PRTEE questionnaire) were measured before treatment, at the end of treatment, and at one- and three-month follow-ups.

RESULTS

The statistically significant improvements were found post-treatment, favoring the VT + PE group in pain intensity (p < 0.001; ES = 0.408), PRTEE-S Pain (p = 0.001; ES = 0.377), PRTEE-S Specific function (p = 0.004; ES = 0.306) and PRTEE-S Total (p = 0.001; ES = 0.355). The VT + PE + EE treatment showed greater effectiveness than the MT + US + EE treatment at immediate post-treatment, as well as at the one-month and three-months follow-up.

CONCLUSIONS

VT and PE added to an EE program could be an effective treatment for pain, ROM, PPT, and function in patients with LE.

Comparison of the effectiveness of two adjustable negative pressure ureteral access sheaths combined with flex ureteroscopy for ≤ 2 cm renal stones

To compare the safety and effectiveness of the combination of intelligent intrarenal pressure control platforms (IPCP) and flexible ureteral access sheath (FUAS) combined with retrograde intrarenal surgery (RIRS) for the treatment of renal stones less than 2 cm. We retrospectively collected 383 patients with renal stones who underwent RIRS in our department from June 2022 to October 2023. Inclusion criteria: stone length or the sum of multiple stone lengths ≤ 2 cm. Finally, 99 cases were included and divided into an IPCP group (n = 40) and FUAS group (n = 59) based on surgical methods. The main endpoint was the stone-free rate (SFR) at third months after surgery, with no residual stones or stone fragments less than 2 mm defined as stone clearance. The secondary endpoints were surgical time and perioperative complications, including fever, sepsis, septic shock, and perirenal hematoma. There was no statistically significant difference in general information between the two groups, including age, gender, body mass index, comorbidities, stone side, stone location, stone length, urine bacterial culture, and hydronephrosis. The operation time for IPCP group and FUAS group was 56.83 ± 21.33 vs 55.47 ± 19.69 min (p = 0.747). The SFR of IPCP group and FUAS group on the first postoperative day was 75.00% vs 91.50% (p = 0.024). The SFR was 90.00% vs 94.90% in the third month (p = 0.349).In IPCP group, there were 11 cases with stones located in the lower renal calyces and 17 cases in FUAS group. The SFR of the two groups on the first day and third months after surgery were 45.50% vs 88.20% (p = 0.014) and 63.60% vs 94.10% (p = 0.040), respectively, with statistical differences. For kidney stones ≤ 2 cm, there was no difference in SFR and the incidence of infection-related complications between IPCP and FUAS combined with RIRS, both of which were superior to T-RIRS. For lower renal caliceal stones, FUAS has a higher SFR compared to IPCP.

Postoperative swelling after elbow surgery: influence of a negative pressure application in comparison to manual lymphatic drainage-a randomized controlled trial

PURPOSE

Postoperative soft tissue swelling is a significant factor influencing outcomes after elbow surgery. It can crucially affect important parameters such as postoperative mobilization, pain, and subsequently the range of motion (ROM) of the affected limb. Furthermore, lymphedema is considered a significant risk factor for numerous postoperative complications. Manual lymphatic drainage is nowadays part of the standardized post-treatment concept, basing on the concept of activating the lymphatic tissue to absorb stagnated fluid from the tissue into the lymphatic system. This prospective study aims to investigate the influence of technical device-assisted negative pressure therapy (NP) on early functional outcomes after elbow surgery. NP was therefore compared to manual lymphatic drainage (MLD). Is a technical device-based NP suitable for treatment of lymphedema after elbow surgery?

METHODS

A total of 50 consecutive patients undergoing elbow surgery were enrolled. The patients were randomized into 2 groups. 25 participants per group were either treated by conventional MLD or NP. The primary outcome parameter was defined as the circumference of the affected limb in cm postoperative up to seven days postoperatively. The secondary outcome parameter was a subjective perception of pain (measured via visual analogue scale, VAS). All parameters were measured on each day of postoperative inpatient care.

RESULTS AND CONCLUSION

NP showed an overall equivalent influence compared to MLD in reducing upper limb swelling after surgery. Moreover, the application of NP showed a significant decrease in overall pain perception compared to manual lymphatic drainage on days 2, 4 and 5 after surgery (p <  0.05).

CONCLUSION

Our findings show that NP could be a useful supplementary device in clinical routine treating postoperative swelling after elbow surgery. Its application is easy, effective and comfortable for the patient. Especially due to the shortage of healthcare workers and physical therapists, there is a need for supportive measures which NP could be.

Histologic features of bone regenerated by means of negative pressure in the context of odontogenic keratocyst

PURPOSE

The objective of the present research is to describe the histologic features of the bone regenerated by means of negative pressure (sugosteogenesis) in a group of patients diagnosed with odontogenic keratocyst (OKC) who underwent active decompression and distraction sugosteogenesis (ADDS) at our institution.

MATERIALS AND METHODS

The authors designed a retrospective case series study. The population included patients with a histologic diagnosis of odontogenic keratocyst in whom active decompression and distraction sugosteogenesis followed by enucleation was performed. All patients were seen and followed from July 2019 to January 2021. The investigation was approved by the Institutional Review Board, and it observed the Declaration of Helsinki on medical protocol. Variables of this study included age, gender, anatomic location (mandible or maxilla), and histologic characteristics of the bone regenerated by means of negative pressure. Histologic features were defined as being consistent or inconsistent with viable mature bone.

RESULTS

Bone biopsies of 6 patients were considered. In total, 83.33% of patients were males and 16.66% females. One hundred percent of the bone samples subjected to negative pressure showed features of viable mature bone.

CONCLUSIONS

In this study, the histological features of the bone subjected to negative pressure demonstrated the normal characteristics of the mature, normal bone.

Endoscopic vacuum therapy as a first-line treatment option for gastric leaks after bariatric surgery: evidence from 10 years of experience

BACKGROUND

Gastric (anastomotic or staple-line) leaks after bariatric surgery are rare but potentially life-threatening complications. Endoscopic vacuum therapy (EVT) has evolved as the most promising treatment strategy for leaks associated with upper gastrointestinal surgery.

OBJECTIVE

The aim of this study was to evaluate the efficiency of our gastric leak management protocol in all bariatric patients over a 10-year period. Special emphasis was placed on EVT treatment and its outcome as a primary treatment or as a secondary treatment when other approaches failed.

SETTING

This study was performed at a tertiary clinic and certified center of reference for bariatric surgery.

METHODS

In this retrospective single-center cohort study, clinical outcomes of all consecutive patients after bariatric surgery from 2012 to 2021 are reported, with special emphasis placed on gastric leak treatment. The primary endpoint was successful leak closure. Secondary endpoints were overall complications (Clavien-Dindo classification) and length of stay.

RESULTS

A total of 1046 patients underwent primary or revisional bariatric surgery, of whom 10 (1.0%) developed a postoperative gastric leak. Additionally, 7 patients were transferred for leak management after external bariatric surgery. Of these, 9 patients underwent primary and 8 patients underwent secondary EVT after futile surgical or endoscopic leak management. The efficacy of EVT was 100%, and there were no deaths. Complications did not differ between primary EVT and secondary treatment of leaks. Length of treatment was 17 days for primary EVT versus 61 days for secondary EVT (P = .015).

CONCLUSIONS

EVT for gastric leaks after bariatric surgery led to rapid source control with a 100% success rate both as primary and secondary treatment. Early detection and primary EVT shortened treatment time and length of stay. This study underlines the potential of EVT as a first-line treatment strategy for gastric leaks after bariatric surgery.

Negative pressure induces dedifferentiation of hepatocytes via RhoA/ROCK pathway

Biomechanical forces are known to regulate the biological behaviors of cells. Although negative pressure has been used for wound healing, it is still unknown about its role in regulating cell plasticity. We investigated whether negative pressure could induce the dedifferentiation of hepatocytes. Using a commercial device, we found that the exposure of primary human hepatocytes to -50 mmHg quickly induced the formation of stress fibers and obviously changed cell morphology in 72 h. Moreover, the exposure of hepatocytes to -50 mmHg significantly upregulated RhoA, ROCK1, and ROCK2 in 1-6 h, and dramatically enhanced the expression of marker molecules on "stemness", such as OCT4, SOX2, KLF4, MYC, NANOG, and CD133 in 6-72 h. However, all these changes in hepatocytes induced by -50 mmHg stimulation were almost abrogated by ROCK inhibitor Y27623. Our data suggest that an appropriate force of negative pressure stimulation can effectively induce the dedifferentiation of hepatocytes via RhoA/ROCK pathway activation.

Liquid-gas phase transition enables microbial electrolysis and H2-based membrane biofilm hybrid system to degrade organic pollution and achieve effective hydrogenotrophic denitrification of groundwater

Electron-donor Lacking was the limiting factor for the denitrification of oligotrophic groundwater and hydrogenotrophic denitrification provided an efficient approach without secondary pollution. In this study, a hybrid system with microbial electrolysis cell (MEC) assisted hydrogen-based membrane biofilm reactor (MBfR) was established for advanced groundwater denitrification. The liquid-gas phase transition prevented the potential pollution from organic wastes in MEC to groundwater, while the bubble-free diffusion of MBfR promoted hydrogen utilization efficiency. The negative-pressure extraction from MEC and the positive pressure for gas supply into MBfR increased the hydrogen proportion and current density of MEC, and improved the kinetic constant K of the denitrification reaction in MBfR. With actual groundwater, the MEC-MBfR hybrid system achieved a nitrate reduction of 97.8% with an effluent NO₃^--N of 2.2 ± 1.0 mg L^-1. The hydrogenotrophic denitrifiers of Thauera, Pannonibacter, and Azonexus, dominated the denitrification biofilm on the membrane and elastic filler in MBfR.

Establishment of Agrobacterium-mediated transformation system to Juglans sigillata Dode 'Qianhe-7'

An efficient genetic transformation system is of great significance for verifying gene function and improving plant breeding efficiency by gene engineering. In this study, a stable Agrobacterium mediated genetic transformation system of Juglans sigillata Dode 'Qianhe-7' was investigated using callus and negative pressure-assisted and ultrasonic-assisted transformation selection. The results showed that the axillary shoot leaves were suitable to induce callus and the callus proliferation rate could reach 516.27% when induction calli were cultured on DKW medium containing 0.5 mg L^-1 indole-3-butyric acid, 1.2 mg L^-1 2,4-dichlorophenoxyacetic acid and 0.5 mg L^-1 kinetin for 18 d. In addition, negative pressure infection was the optimal infection method with the lowest browning rate (0.00%), high GFP conversion rate (16.67%), and better growth status. To further prove the feasibility of this genetic transformation system, the flavonol synthetase (JsFLS₅) gene was successfully transformed into the into leaf-derived callus of 'Qianhe-7'. JsFLS₅ expression and the content of total flavonoids in transformed callus were improved significantly compared with the untransformed callus, which proved that we had an efficient and reliable genetic transformation system using leaf-derived callus of Juglans sigillata.

Removal of collagen three-dimensional scaffold bubbles utilizing a vacuum suction technique

The process of generating type I/II collagen scaffolds is fraught with bubble formation, which can interfere with the three-dimensional structure of the scaffold. Herein, we applied low-temperature vacuum freeze-drying to remove mixed air bubbles under negative pressure. Type I and II rubber sponges were acid-solubilized via acid lysis and enzymolysis. Thereafter, vacuum negative pressure was applied to remove bubbles, and the cover glass press method was applied to shape the type I/II original scaffold. Vacuum negative pressure was applied for a second time to remove any residual bubbles. Subsequent application of carbamide/N-hydroxysuccinimide cross-linked the scaffold. The traditional method was used as the control group. The structure and number of residual bubbles and pore sizes of the two scaffolds were compared. Based on the relationship between the pressure and the number of residual bubbles, a curve was created, and the time of ice formation was calculated. The bubble content of the experimental group was significantly lower than that of the control group (P < 0.05). The pore diameter of the type I/II collagen scaffold was higher in the experimental group than in the control group. The time of icing effect of type I and II collagen solution was 136.54 ± 5.26 and 144.40 ± 6.45 s, respectively. The experimental scaffold had a more regular structure with actively proliferating chondrocytes that possessed adherent pseudopodia. The findings indicated that the vacuum negative pressure method did not affect the physical or chemical properties of collagen, and these scaffolds exhibited good biocompatibility with chondrocytes.

Reducing donor-site complications in DIEP flap breast reconstruction with closed incisional negative pressure therapy: A cost-benefit analysis

INTRODUCTION

Deep inferior epigastric perforator (DIEP) flaps are considered the gold standard for autologous breast reconstruction but create large abdominal incisions that risk donor-site morbidity during harvest. Closed incision negative pressure therapy (ciNPT) is emerging as an effective alternative to standard postoperative dressings, but there is a paucity of data in DIEP flap donor sites.

METHODS

We conducted a retrospective case-control study investigating the use of ciNPT in DIEP flap donor sites at a single institution between March 2017 and September 2021. Patients who underwent microsurgical autologous breast reconstruction with DIEP flaps were included. Patients were divided into those with donor incision sites managed with ciNPT (n = 24) and those with conventional postoperative wound dressings (n = 20). We compared patient demographics, wound drainage volumes and postoperative outcomes between the two groups. A cost-benefit analysis was employed to compare the overall costs associated with each complication and differences in length of stay between the two groups.

RESULTS

There was no statistically significant difference in age, body mass index (BMI), comorbidity burden or smoking status between the two groups. Both groups had similar lengths of stay and wound drainage volumes with no readmissions or reoperations in either group. There was a statistically significant reduction in donor-site complications (p = 0.018), surgical site infections (p = 0.014) and seroma formation (p = 0.016) in those with ciNPT. Upon cost-benefit analysis, the ciNPT group had a mean reduction in cost-per-patient associated with postoperative complications of £420.77 (p = 0.031) and £446.47 (p = 0.049) when also accounting for postoperative length of stay CONCLUSION: ciNPT appears to be an effective alternative incision management system with the potential to improve complication rates and postoperative morbidity in DIEP flap donor sites. Our analysis demonstrates improved cost-benefit outweighing the increase in costs associated with ciNPT. We recommend a multicentre prospective trial with formal cost-utility analysis to strengthen these findings.

Cost Savings Associated with Vacuum-Assisted Closure in Trauma Patients Undergoing Posterior Spinal Fusion

OBJECTIVE

To investigate the implications of vacuum-assisted closure (VAC) versus standard wound dressings on postoperative posterior spinal fusion (PSF) wounds with respect to potential cost savings associated with reduced incidence of surgical site infections.

METHODS

This was a retrospective review of trauma patients who underwent open PSF under the care of a single surgeon at a Level I trauma center. Patients were postoperatively monitored for 90 days. Statistical analysis was performed with χ² testing with the calculation of number needed to treat values.

RESULTS

Inclusion criteria were met by 208 patients who underwent open PSF. The χ² test revealed a significant increase in incidence of surgical site infections (20% vs. 8%; P = 0.021) in the non-VAC group (n = 112) compared with the VAC group (n = 96). Cost-benefit analysis revealed that use of VAC in patients undergoing open PSF could enable a mean cost savings of $163,492 per 100 patients.

CONCLUSIONS

Use of VAC in patients undergoing open PSF was associated with a 2-fold decrease in incidence of surgical site infections and an infection-related cost savings of $163,492 per 100 patients. Further investigation is needed to ascertain additional benefits of VAC usage in patients undergoing open PSF.

Optimized mechanism for fast removal of infectious pathogen-laden aerosols in the negative-pressure unit

It has been frequently emphasized that highly contagious respiratory disease pathogens (such as SARS-CoV-2) are transmitted to the other hosts in the form of micro-sized aerosols (< 5 μm) in the air without physical contacts. Hospital environments such as negative-pressure unit are considered being consistently exposed to pathogens, so it is essential to quickly discharge them through the effective ventilation system. To achieve that, in the present study, we propose the optimized ventilation mechanism and design for the fastest removal of pathogen-laden aerosol using numerical simulations. We quantitatively evaluated the aerosol removal performance of various ventilation configurations (combinations of air exhaust and supply ducts), and found that the key mechanism is to form the coherent (preferentially upward) airflow structure to surround the respiratory flow containing the aerosol cluster. We believe that the present findings will play a critical role in developing the high-efficiency negative-pressure facility irrespective of its size and environments.

Novel strategy for rapid start-up and stable operation of anammox: Negative pressure coupled with the direct-current electric field

An application challenge of anaerobic ammonia oxidation (anammox) is the slow proliferation rate of anaerobic ammonium oxidation bacteria (AnAOB). This study adopted negative pressure coupled with the direct-current electric field (NP-DCEF) to evaluate system nitrogen removal performance. Results showed that the total nitrogen removal rate (TNRR) of the NP-DCEF system was stable at 88.6% after seven days. Compared with that of the ordinary operating system (45.4%), the relative abundance of Candidatus-kuenenia considerably increased from 51.9% to 57.6%. Under transient and long-term influent fluctuation, the NP-DCEF system showed high nitrogen removal performance. The specific activity of AnAOB (SAA) reached 11.0 mg N∙g Vss^-1 h^-1 under load fluctuation, and it was 8.7 mg N∙g Vss^-1 h^-1 under ordinary operational conditions. In addition, the specific activities of hydrazine dehydrogenase (HDH) and hydrazine synthetase (HZS) reached 32.66 and 92.95 U∙L^-1, which are considerably higher than those under the ordinary operating conditions (18.41 and 63.20 U∙L^-1). These results indicated that the novel operation strategy has specific feasibility and potential for the start-up and long-term operation of anammox.

Non-contact optical characterization of negative pressure in hydrogel voids and microchannels

Negative pressure in water under tension, as a thermodynamic non-equilibrium state, has facilitated the emergence of innovative technologies on microfluidics, desalination, and thermal management. However, the lack of a simple and accurate method to measure negative pressure hinders further in-depth understanding of the properties of water in such a state. In this work, we propose a non-contact optical method to quantify the negative pressure in micron-sized water voids of a hydrogel film based on the microscale mechanical deformation of the hydrogel itself. We tested three groups of hydrogel samples with different negative pressure inside, and the obtained results fit well with the theoretical prediction. Furthermore, we demonstrated that this method can characterize the distribution of negative pressure, and can thus provide the possibility of investigation of the flow behavior of water in negative pressure. These results prove this technique to be a promising approach to characterization of water under tension and for investigation of its properties under negative pressure.

[A mobile care unit dedicated to airbone infections]

A mobile care unit has been designed for infectious patients care in a humanitarian setting. Six individual compartments are grouped together in the main tent of 54 m² under negative air pressure. The principle of walking from clean to dirty is respected. The main indications are bacterial or viral infections with airborne transmission and an epidemic potential. The operating situations of this prototype, which has not yet been tested in the field, and its constraints in an underdeveloped country are presented.

Genesis of "negative pressure" during hanging drop; the answer is positive pressure

A drop of saline placed within the hub of an epidural needle is sucked in when the needle is advanced and penetrates through a polyurethane foam cube. This phenomenon might be explained by the release of compressed air inside of the needle into the air. The positive pressure inside of the needle may be generated by advancing of the needle. To prove this hypothesis, the pressure inside of the needle was measured during needle advancement, and it increased gradually and then dropped to zero suddenly when the needle fully penetrated the polyurethane foam block. We can speculate that the same phenomenon occurs during hanging-drop method of epidural anesthesia, and this may occur regardless of whether epidural subatmospheric pressure exists or not.

A new technique to detect communication sites for pleuroperitoneal communication

Pleuroperitoneal communication is one of the complications for continuous ambulatory peritoneal dialysis. Communication sites, such as defects or bleb-like lesions, are found in the diaphragm, but it is sometimes difficult to detect these sites. We combined the infrared thoracoscopy and negative pressure technique to detect communication sites. We think our new technique will become an alternative option for difficult and complex cases.

Evolution of endoscopic vacuum therapy for upper gastrointestinal leakage over a 10-year period: a quality improvement study

BACKGROUND

Endoscopic vacuum therapy (EVT) is an effective treatment option for leakage of the upper gastrointestinal (UGI) tract. The aim of this study was to evaluate the clinical impact of quality improvements in EVT management on patients' outcome.

METHODS

All patients treated by EVT at our center during 2012-2021 were divided into two consecutive and equal-sized cohorts (period 1 vs. period 2). Over time several quality improvement strategies were implemented including the earlier diagnosis and EVT treatment and technical optimization of endoscopy. The primary endpoint was defined as the composite score MTL30 (mortality, transfer, length-of-stay > 30 days). Secondary endpoints included EVT efficacy, complications, in-hospital mortality, length-of-stay (LOS) and nutrition status at discharge.

RESULTS

A total of 156 patients were analyzed. During the latter period the primary endpoint MTL30 decreased from 60.8 to 39.0% (P = .006). EVT efficacy increased from 80 to 91% (P = .049). Further, the need for additional procedures for leakage management decreased from 49.9 to 29.9% (P = .013) and reoperations became less frequent (38.0% vs.15.6%; P = .001). The duration of leakage therapy and LOS were shortened from 25 to 14 days (P = .003) and 38 days to 25 days (P = .006), respectively. Morbidity (as determined by the comprehensive complication index) decreased from 54.6 to 46.5 (P = .034). More patients could be discharged on oral nutrition (70.9% vs. 84.4%, P = .043).

CONCLUSIONS

Our experience confirms the efficacy of EVT for the successful management of UGI leakage. Our quality improvement analysis demonstrates significant changes in EVT management resulting in accelerated recovery, fewer complications and improved functional outcome.

The Influence of Low- and High-Negative-Pressure Liposuction and Different Harvesting Sites on the Viability and Yield of Adipocytes and Other Nucleated Cells

BACKGROUND

The volume effect of fat grafting is highly dependent on the presence of viable adipocytes and other nucleated cells within the lipoaspirate. We suspected that one of the crucial factors influencing cell viability is the negative pressure applied during the fat graft harvesting and the suitability of various harvest sites when compared to others. Despite much discussion, there is no consensus on the optimal negative pressure or the best site for harvesting so we designed an experiment to test this.

METHODS

Fat graft taken under low negative pressure (- 200 mmHg) or high negative pressure (- 700 mmHg) from the thigh or abdominal regions from 21 healthy human donors was evaluated. The principal variables studied were: a) total number and viability of nucleated cells, b) liposuction duration and c) blood admixture. Other variables studied were body mass index, the impact of age and enzymatic digestion.

RESULTS

The absolute number and viability of nucleated cells and the blood admixture did not differ significantly between lipoaspirates obtained under different vacuum conditions or from different regions. The time taken to acquire the same volume of lipoaspirate was significantly increased using low negative pressure. The time taken to collect cells in the thigh region significantly increased with increasing BMI but this correlation was not found when harvesting in the abdominal region. The BMI and age did not impact the results in any of the measured variables. The enzymatic digestion rate was independent of the negative pressure used to harvest.

CONCLUSION

Our results indicate that neither the negative pressure used nor the area chosen has any significant influence on the viability and yield of harvested cells. The time taken to obtain lipoaspirate using low pressure is significantly longer than when using high pressure. No significant difference was found in the value of blood admixture using different vacuum pressures, and no correlation exists between the body mass index and the cell viability or age of the patients and the time of liposuction.

LEVEL OF EVIDENCE III

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 Table of Contents or online Instructions to Authors www.springer.com/00266 .

Implementation and acceptance rates of a specially designed vacuometer for the vacuum bell treatment of pectus excavatum

BACKGROUND / PURPOSE

To report the implementation of a specially designed vacuometer for the ambulatory measurement of the exact negative pressure self-applied by the patient when using the vacuum bell for the treatment of pectus excavatum and to analyze patient satisfaction with the device, by conducting a survey.

METHODS

Between October 2018 and June 2020, all patients with pectus excavatum who received a vacuum bell at our Pectus Clinic were provided with a specially designed pectus vacuometer for their personal use. We described the vacuometer, the fundamentals of its development, and the utilization protocol. A survey was conducted evaluating comfort, clarity of instructions, usefulness, simplicity of connection, and likeability. The level of satisfaction was assessed using a Likert scale ranging from 1 (very negative experience) to 5 (very positive experience). The occurrence of skin lesions provoked by the application of the vacuum bell was registered.

RESULTS

From 72 submitted surveys, 54 patients answered. Patient demographics comprised 44 (81.5%) males and a mean age of 12.6 ± 6.0 years. The mean initial external pectus depth was 2.0 ± 0.7 cm and the mean duration of treatment was 13.2 ± 8.6 months. No skin lesions were detected while using the vacuum bell and the vacuometer. The mean general satisfaction score was 4.4 ± 0.7 and 83.3% of the respondents did not have any inconvenience with the vacuometer. A patient who considered himself cured was the only dropout during the study.

CONCLUSIONS

In this study, we described the feasibility and fundamentals of the application of a specifically designed vacuometer for ambulatory use as an adjunct to the treatment of pectus excavatum with a vacuum bell, and demonstrated a high satisfaction level with the device. In addition, the vacuometer might help avoid skin lesions secondary to the vacuum bell and foster adhesion to treatment.

TYPE OF STUDY

Treatment study.

LEVEL OF EVIDENCE

IV.

The Influence of High and Low Negative Pressure Liposuction and Various Harvesting Techniques on the Viability and Function of Harvested Cells-a Systematic Review of Animal and Human Studies

BACKGROUND

An understanding of fat grafting methodology, techniques and patient-related factors is crucial when considering fat grafting. Multiple factors can influence the success of a fat graft and consequently the outcome of the procedure. The aim of this systematic review is to elucidate the influence of negative pressure and various techniques of fat harvesting on the viability and function of cells, particularly adipocytes and adipose-derived stem cells.

METHODS

We conducted a literature search from 1975 to 2020 using the PubMed bibliography, ScienceDirect, SCOPUS and the Google Scholar databases which produced 168,628 articles on the first pass. After applying all the exclusion criteria by two independent reviewers, we were left with 21 articles (level IV of Oxford Centre for Evidence-Based Studies and Grade C of Grade Practice Recommendation from the American Society of Plastic Surgeons) on which this review is based.

RESULTS

From 11 studies focused on different negative pressures, no one found using high negative pressure advantageous. Summarising 13 studies focused on various harvesting techniques (excision, syringe, and pump-machine), most often equal results were reported, followed by excision being better than either syringe or liposuction.

CONCLUSION

From our systematic review, we can conclude that the low negative pressure seems to yield better results and that the excision seems to be the most sparing method for fat graft harvesting. However, we have to point out that this conclusion is based on a very limited number of statistically challengeable articles and we recommend well-conducted further research.

LEVEL OF EVIDENCE III

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 .

Management of post lobectomy subcutaneous emphysema; a case report with literature review

Introduction

Subcutaneous emphysema is an extremely rare complication after lobectomy. The current study aims to report a case of lung cancer developing extensive subcutaneous emphysema after lobectomy.

Case presentation

A 73-year-old man presented with dyspnea and cough for one month duration associated with wheeze and sputum. He was a chronic heavy smoker (100 pack/year). Work up revealed squamous cell carcinoma. Although he had poor pulmonary function tests, he underwent left upper lobectomy. On the fifth postoperative day, he was discharged from the hospital as there was no air leak and the lung remained expanded 15 hours after clamping of the thoracostomy tube. Two days later, the patient developed generalized subcutaneous emphysema. The patient was re-admitted to the hospital and a thoracostomy tube was inserted. The lung expanded upon insertion while the subcutaneous emphysema remained the same and even slightly increased over night. A 3 cm incision was made at the left infra-clavicular area and a negative pressure applied to it. The subcutaneous emphysema completely subsided a few hours after this intervention.

Discussion

Because of the benign course, the majority of cases of subcutaneous emphysema (mild to moderate) only need nonoperative management alongside treatment of the predisposing factors. These patients may need nothing other than bed rest, good analgesia, supplemental oxygen, and reassurance.

Conclusion

Subcutaneous emphysema after lobectomy prolongs hospital stay. It mainly occurs in cases with poor pulmonary function tests, steroid use, and those with extensive adhesion.

•

Subcutaneous emphysema is one of the complications following thoracic surgery.

•

Subcutaneous emphysema might be a benign and self-limiting condition.

•

It might be a serious condition that ends with respiratory failure and death.

•

In this report, a case of lung cancer developing subcutaneous emphysema after lobectomy discussed.

A Novel Negative Pressure, Face-Mounted Antechamber to Minimize Aerosolization of Particles During Endoscopic Skull Base Surgery

BACKGROUND

The COVID-19 pandemic has revealed deficiencies in the adequacy of personal protective equipment (PPE) for healthcare workers. Endoscopic endonasal skull base surgery is thought to be among the highest-risk aerosol-generating procedures for surgeons and operating room personnel.

OBJECTIVE

To validate the efficacy and clinical feasibility of a novel surgical device.

METHODS

A low-cost, modifiable, and easily producible negative pressure, face-mounted antechamber was developed utilizing 3D printing and silicone molding. Efficacy was evaluated using an optical particle sizer to quantify aerosols generated during both cadaver and intraoperative human use with high-speed drilling.

RESULTS

Particle counts in the cadaver showed that drilling led to a 2.49-fold increase in particles 0.3 to 5 μm (P = .001) and that the chamber was effective at reducing particles to levels not significantly different than baseline. In humans, drilling led to a 37-fold increase in particles 0.3 to 5 μm (P < .001), and the chamber was effective at reducing particles to a level not significantly different than baseline. Use of the antechamber in 6 complex cases did not interfere with the ability to perform surgery. Patients did not report any facial discomfort after surgery related to antechamber use.

CONCLUSION

The use of a negative pressure facial antechamber can effectively reduce aerosolization from endoscopic drilling without disturbing the flow of the operation. The antechamber, in conjunction with appropriate PPE, will be useful during the COVID-19 pandemic, as well as during flu season and any future viral outbreaks.

[Study on the Application of A New Type of Anhydrous Thoracic Negative Pressure Drainage Device in Patients after Thoracic Surgery]

BACKGROUND

After general thoracic surgery, a chest tube is usually placed for closed drainage to expel gas accumulation in the thoracic cavity and fluid accumulation to promote lung re-expansion. It can also be observed whether there is active bleeding after the operation and whether there is a pulmonary leak. The conventional drainage of the chest cavity is connected with a water-sealed drainage bottle, and the patient condition is judged by observing the drainage situation and the fluctuation of the water column, which is a very classic method. However, the water-sealed bottle has the disadvantages of being easy to overturn and inconvenient to carry, which is not conducive to the early activities of patients. Under the concept of accelerated rehabilitation, our center applied a new type of anhydrous thorax negative pressure drainage device and achieved good results. The purpose of this study was to observe the effect of a new type of anhydrous thoracic negative pressure drainage device in patients after thoracic surgery.

METHODS

Retrospective analysis of patients who underwent lung surgery in the First Affiliated Hospital of Zhejiang University Medical College from January 2018 to December 2019, patients were divided into two groups. One group of patients used a traditional closed-chest drainage water-sealed bottle as a control group, and the other group used a new type of anhydrous negative-pressure drainage bottle as an experimental group. Patients' gender, age, hypertension, diabetes, smoking history, surgical incisions and surgical methods, and the length of hospital stay and postoperative hospital stay were calculated.

RESULTS

There were no statistical differences in age, gender, comorbidities (hypertension, diabetes, smoking history), scope of surgery, and duration of surgery between the two groups of patients, but there were statistical differences in surgical incisions between the two groups of patients (P=0.01). We found that patients using the new waterless negative pressure drainage device were shorter than patients with water negative pressure drainage device in terms of postoperative hospital stay and total hospitalization time, and the difference was statistically significant (P=0.02, P=0.04).

CONCLUSIONS

The new type of anhydrous thoracic negative pressure drainage device has a good effect on the rapid recovery and advancement after thoracic surgery.

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.