Blood trauma in veno-venous extracorporeal membrane oxygenation: low pump pressures and low circuit resistance matter.

BACKGROUND: Veno-venous extracorporeal membrane oxygenation (VV ECMO) has become standard of care in patients with the most severe forms of acute respiratory distress syndrome. However, hemolysis and bleeding are one of the most frequent side effects, affecting mortality. Despite the widespread use of VV ECMO, current protocols lack detailed, in-vivo data-based recommendations for safe ECMO pump operating conditions. This study aims to comprehensively analyze the impact of VV ECMO pump operating conditions on hemolysis by combining in-silico modeling and clinical data analysis. METHODS: We combined data from 580 patients treated with VV ECMO in conjunction with numerical predictions of hemolysis using computational fluid dynamics and reduced order modeling of the Rotaflow (Getinge) and DP3 (Xenios) pumps. Blood trauma parameters across 94,779 pump operating points were associated with numerical predictions of shear induced hemolysis. RESULTS: Minimal hemolysis was observed at low pump pressures and low circuit resistance across all flow rates, whereas high pump pressures and circuit resistance consistently precipitated substantial hemolysis, irrespective of flow rate. However, the lower the flow rate, the more pronounced the influence of circuit resistance on hemolysis became. Numerical models validated against clinical data demonstrated a strong association (Spearman's r = 0.8) between simulated and observed hemolysis, irrespective of the pump type. CONCLUSIONS: Integrating in-silico predictions with clinical data provided a novel approach in understanding and potentially reducing blood trauma in VV ECMO. This study further demonstrated that a key factor in lowering side effects of ECMO support is the maintenance of low circuit resistance, including oxygenators with the lowest possible resistance, the shortest feasible circuit tubing, and cannulae with an optimal diameter.

Pressure induces peritoneal fibrosis and inflammation through CD44 signaling.

Peritoneal dialysis (PD) is a widely used sustainable kidney replacement therapy. Prolonged use of PD fluids is associated with mesothelial-mesenchymal transition, peritoneal fibrosis, and eventual ultrafiltration (UF) failure. However, the impact of pressure on the peritoneum remains unclear. In the present study, we hypothesized increased pressure is a potential contributing factor to peritoneal fibrosis and investigated the possible mechanisms. In vitro experiments found that pressurization led to a mesenchymal phenotype, the expression of fibrotic markers and inflammatory factors in human mesothelial MeT-5A cells. Pressure also increased cell proliferation and augmented cell migration potential in MeT-5A cells. The mouse PD model and human peritoneum equilibrium test (PET) data both showed a positive association between higher pressure and increased small solute transport, along with decreased net UF. Mechanistically, we found that significant upregulation of CD44 in mesothelial cells upon pressurization. Notably, the treatment of CD44 neutralizing antibodies prevented pressure-induced phenotypic changes in mesothelial cells, while a CD44 inhibitor oligo-fucoidan ameliorated pressure-induced peritoneal thickening, fibrosis, and inflammation in PD mice. To conclude, intraperitoneal pressure results in peritoneal fibrosis in PD via CD44-mediated mesothelial changes and inflammation. CD44 blockage can be utilized as a novel preventive approach for PD-related peritoneal fibrosis and UF failure.

Prediction of tissue deformation based on mechanical and physiological factors in the prone position during surgery.

AIM: This study aimed to predict tissue deformation based on the pressure applied while lying in the prone position and physiological factors. METHODS: Healthy volunteers were instructed to lie on mattresses of four different hardness levels (50, 87.5, 175, and 262.5 N). The order in which the mattresses were used was randomized per participant. Pressure at the iliac crests was measured using a pressure mapping sensor sheet. Participants were placed in the prone position for 10 min, with pressure data used from the latter 5 min. For the tissue deformation at the iliac crests, our previous study data were used. Multiple regression analysis was used to identify predictive mechanical and physiological factors. RESULTS: The distance between the left and right greater trochanters, maximum interface pressure and age were significant predictors for compression of the skin and soft tissue. Significant predictors of internal soft tissue displacement were the distances between the left and right anterior superior iliac spines and greater trochanters. No factors predicted skin surface displacement. CONCLUSIONS: Our study provided predictive factors that may be measured easily in a clinical setting to reduce the risk of pressure ulcers during surgery in the prone position.

Associations between body mass index and interface pressure after 3 h loading in healthy adults.

AIM OF THE STUDY: The purpose of this study was to determine the associations between body mass index and interface pressure after 3 h loading in healthy adults and to establish a foundation for the development of interventions tailored to body mass index. MATERIAL AND METHODS: A secondary data analysis based on a clinical trial involving 75 adults was conducted. Data were analyzed using descriptive statistics, repeated measure ANOVA, and ANCOVA. The statistics program IBM SPSS Statistics 27.0 was used for data analysis. RESULTS: Loading caused a significant increase in average pressure in the obesity group compared to the underweight group. There was a significant increase in risk area ratio calculated based on 30 mmHg and 45 mmHg in both obesity and overweight groups compared to the underweight group. On both support surfaces, average pressure, peak pressure, and risk area ratio were higher in the obese group compared to the normal weight group. However, these differences were not statistically significant. CONCLUSION: Given the emphasized risk of pressure injuries, long-term observation of body mass index-specific changes in interface pressure can provide crucial evidence for pressure injury prevention nursing. The results of this study suggest the need to implement pressure injury prevention interventions that consider the pressure characteristics according to BMI.

Continuous cuff pressure control on middle-aged and elderly patients undergoing endoscopic submucosal dissection of the esophagus effect of airway injury.

OBJECTIVE: Assessment of the effect of continuous cuff pressure control on airway injury in middle-aged and elderly patients undergoing endoscopic submucosal dissection (ESD). METHOD: A total of 104 eligible middle-aged and elderly patients requiring esophageal ESD from July 2022-September 2023 at the First Affiliated Hospital of Nanchang University were selected and randomly divided into two groups: the group undergoing general anesthesia tracheal intubation with continuous control of cuff pressure after intubation (Group A, n = 51) and the group undergoing general anesthesia tracheal intubation with continuous monitoring without control of cuff pressure (Group B, n = 53). After endotracheal intubation in Group A, under the guidance of an automatic cuff pressure controller, the air was used to inflate the tracheal cuff until the cuff pressure was 25-30cmH2O. The cuff pressure after intubation was recorded, and then the cuff pressure parameters were directly adjusted in the range of 25-30cmH2O until tracheal extubation after the operation. After endotracheal intubation, patients in Group B inflated the tracheal cuff with clinical experience, then monitored and recorded the cuff pressure with a handheld cuff manometer and instructed the cuff not to be loosened after being connected to the handheld cuff manometer-continuous monitoring until the tracheal extubation, but without any cuff pressure regulation. The patients of the two groups performed esophageal ESD. The left recumbent position was taken before the operation, and the cuff's pressure was recorded. Then, insert the gastrointestinal endoscope to find the lesion site and perform appropriate CO2 inflation to display the diseased esophageal wall for surgical operation fully. After determining the location, the cuff pressure of the two groups was recorded when the cuff pressure was stable. After the operation, the upper gastrointestinal endoscope was removed and the cuff pressure of the two groups was recorded. Postoperative airway injury assessment was performed in both groups, and the incidence of sore throat, hoarseness, cough, and blood in sputum was recorded. The incidence of postoperative airway mucosal injury was also observed and recorded in both groups: typical, episodic congestion spots and patchy local congestion. RESULT: The incidence of normal airway mucosa in Group A was higher than that in Group B (P < 0.05). In comparison, the incidence of occasional hyperemia and local plaque congestion in Group A was lower than in Group B (P < 0.05). CONCLUSION: Continuous cuff pressure control during operation can reduce airway injury in patients with esophageal ESD and accelerate their early recovery after the operation.

Cardiopulmonary Resuscitation-associated Lung Edema (CRALE). A Translational Study.

Rationale: Cardiopulmonary resuscitation is the cornerstone of cardiac arrest (CA) treatment. However, lung injuries associated with it have been reported.Objectives: To assess 1) the presence and characteristics of lung abnormalities induced by cardiopulmonary resuscitation and 2) the role of mechanical and manual chest compression (CC) in its development.Methods: This translational study included 1) a porcine model of CA and cardiopulmonary resuscitation (n = 12) and 2) a multicenter cohort of patients with out-of-hospital CA undergoing mechanical or manual CC (n = 52). Lung computed tomography performed after resuscitation was assessed qualitatively and quantitatively along with respiratory mechanics and gas exchanges.Measurements and Main Results: The lung weight in the mechanical CC group was higher compared with the manual CC group in the experimental (431 ± 127 vs. 273 ± 66, P = 0.022) and clinical study (1,208 ± 630 vs. 837 ± 306, P = 0.006). The mechanical CC group showed significantly lower oxygenation (P = 0.043) and respiratory system compliance (P < 0.001) compared with the manual CC group in the experimental study. The variation of right atrial pressure was significantly higher in the mechanical compared with the manual CC group (54 ± 11 vs. 31 ± 6 mm Hg, P = 0.001) and significantly correlated with lung weight (r = 0.686, P = 0.026) and respiratory system compliance (r = -0.634, P = 0.027). Incidence of abnormal lung density was higher in patients treated with mechanical compared with manual CC (37% vs. 8%, P = 0.018).Conclusions: This study demonstrated the presence of cardiopulmonary resuscitation-associated lung edema in animals and in patients with out-of-hospital CA, which is more pronounced after mechanical as opposed to manual CC and correlates with higher swings of right atrial pressure during CC.

Mechanical Pressure Driving Proteoglycan Expression in Mammographic Density: a Self-perpetuating Cycle?

Regions of high mammographic density (MD) in the breast are characterised by a proteoglycan (PG)-rich fibrous stroma, where PGs mediate aligned collagen fibrils to control tissue stiffness and hence the response to mechanical forces. Literature is accumulating to support the notion that mechanical stiffness may drive PG synthesis in the breast contributing to MD. We review emerging patterns in MD and other biological settings, of a positive feedback cycle of force promoting PG synthesis, such as in articular cartilage, due to increased pressure on weight bearing joints. Furthermore, we present evidence to suggest a pro-tumorigenic effect of increased mechanical force on epithelial cells in contexts where PG-mediated, aligned collagen fibrous tissue abounds, with implications for breast cancer development attributable to high MD. Finally, we summarise means through which this positive feedback mechanism of PG synthesis may be intercepted to reduce mechanical force within tissues and thus reduce disease burden.

Identification of Risk Factors for Intraoperative Acquired Pressure Injury in Patients Undergoing Neurosurgery: A Retrospective Single-Center Study.

BACKGROUND Risk factors for intraoperative acquired pressure injury (IAPI) in patients undergoing various surgical procedures have been described in previous studies. However, whether risk factors for IAPI in patients undergoing neurosurgery differ remains unknown. The aim of the present study was to explore independent risk factors for IAPI in patients undergoing neurosurgery. MATERIAL AND METHODS Data from 465 patients who underwent neurosurgery between October 2017and December 2018 and who were at high risk of IAPIs were retrospectively analyzed. Independent risk factors for IAPI were evaluated using univariate and multivariate logistic regression models. RESULTS Sixty-nine IAPIs (14.8%) in 465 patients undergoing neurosurgery were assessed. Multivariate logistic regression analyses showed that being overweight (odds ratio [OR] 2.685; 95% confidence interval [CI] 1.206-5.975; P=0.016), prone position (OR 7.502, 95% CI 2.470-22.787. P<0.001), lateral position (OR 15.301, 95% CI 4.903-47.753, P<0.001), use of a head frame (OR 3.716, 95% CI 1.431-9.653, P=0.007), surgical times of 4 to 8 h (OR 7.276, 95% CI 2.249-23.542, P<0.001), and surgical times ≥8 h (OR 173.248, 95% CI 32.629-919.896, P<0.001) all were associated with an increased risk of IAPI in patients undergoing neurosurgery. The factors associated with reduced risk of IAPI were high serum albumin levels (OR 0.099, 95% CI 0.016-0.608, P=0.013) and use of memory sponge pads (OR 0.064, 95% CI 0.020-0.202, P<0.001). CONCLUSIONS The present study indicates that being overweight, prone and lateral positioning, use of a head frame, and longer surgical times are associated with an increased risk of IAPI in patients undergoing neurosurgery. Prospective studies should be conducted to verify these findings and consideration should be given to use of these factors in clinical practice to identify high-risk patients.

Effects of tubing degradation and pump position on extracorporeal circulation performance.

Extracorporeal circulation (ECC) is an integral part of cardiac surgery. Yet, the contact with artificial surfaces, mechanical stress, shear, and suction forces within the ECC pose a pronounced risk for damaging the corpuscular components of the blood. These suction forces may be reduced by a repositioning of the roller pumps employed below the reservoir. Furthermore, the repeated compression of the involved silicone tubing is likely to cause degradation. We present our observations regarding changes in the ECC performance following this degradation process. In vitro experiments were performed in a standard as well as a simplified ECC setup and included measurements of pressure, effective flow, and tubing restoring force over a time frame of 12 hours with two different pump positions utilizing transit time flow measurement. Suction forces within the tubing could be significantly reduced by shifting the pump position below the reservoir. Regardless of the setup, the tubing showed significant loss of restoring force as well as effective flow over time. A shift of the pump position within the ECC setup can be recommended to prevent blood damaging negative pressures. Further research is necessary to evaluate the exact cause of the reduction of restoring force overtime as well as its risks for the patients. Finally, our results underline the importance of transit time flow measurements to collect reliable flow data.

Compression asphyxia and other clinicopathological findings from the Hillsborough Stadium disaster.

Ninety-six people died following a crowd crush at the Hillsborough Football Stadium, Sheffield, UK in 1989. The cause of death in nearly all cases was compression asphyxia. The clinical and pathological features of deaths encountered in crowds are discussed with a particular focus on the Hillsborough disaster.

The effect of total compression time and rate (slope) of compression on the incidence of symptomatic Eustachian tube dysfunction and middle ear barotrauma: a Phase II prospective study.

Eustachian tube dysfunction (ETD) and middle ear barotrauma (MEB) are common reported complications during hyperbaric oxygen treatment. Our Phase I study data was the first to demonstrate a statistically significant decrease in the occurrence of symptomatic ETD and MEB. The Phase I Trial suggested the total time interval and rate (slope) of compression (ROC) may be a determining factor in ETD and MEB. This Phase II study investigates an optimal rate of compression to reduce ETD and MEB when considering each multiplace treatment (with multiple patients) as the unit of observation as a group, rather than for each individual patient. Data were collected prospectively on 1,244 group patient-treatment exposures, collectively including 5,072 individual patient-treatment/exposures. We randomly assigned patient-treatment group exposures to four different time interval and rate (slope) of compression. These compression rates and slopes were identical to those used in the Phase I trial. All patients experiencing symptoms of MEB requiring compression stops were evaluated post treatment for the presence of ETD and MEB using the O'Neill Grading System (OGS) for ETD. Data were analyzed using the IBM-SPSS statistical software program. A statistically significant decrease in the number of compression holds was observed in the 15-minute compression schedule, correlating to the results observed in the Phase I trial. The 15-minute linear compression profile continues to demonstrate the decreased need for patient symptomatic compression stops (as in the Phase I trial) using a USN TT9 during elective hyperbaric oxygen treatments in a Class A multiplace hyperbaric chamber. Trial Registration: ClinicalTrials.gov Identifier: NCT04776967.

Pressure-Measuring Devices for Compression Therapy in Venous Leg Ulcers: A Comprehensive Review.

OBJECTIVE: To investigate the evolution of pressure-measuring devices used in compression treatment for venous leg ulcers and assess the most practical and effective devices to determine optimal pressure in compression therapy. DATA SOURCES: Relevant information was retrieved from databases including Google Scholar, PubMed, Wiley Online, and ScienceDirect without publication date restrictions. The keywords included venous leg ulcer, compression therapy, pressure measuring device, pressure sensor, and wireless system. STUDY SELECTION: Studies included in the review had to be published in English and discuss or compare pressure-measuring devices/sensors for compression therapy, the development of alternative sensors, and the applications of wireless technologies. Veterinary studies, conference proceedings, and unpublished articles were excluded. Applicable studies and articles were critically evaluated and synthesized. DATA EXTRACTION: After abstract review, 39 studies were identified. During full-text review, study details were collected using a data extraction form and organized into tables. Device attributes, accuracy, price, and limitations were categorized and analyzed. DATA SYNTHESIS: Studies disagree on the effectiveness and user-friendliness of existing pressure-measuring devices. These devices often impact user comfort and convenience, which are crucial factors in the adoption and use of wearable devices. Potential solutions for pressure-measuring devices with promising technologies were proposed: four feasible alternative sensors are described that could improve comfort and facilitate prolonged use under bandages. Advanced communication technologies may provide more convenience for users and practitioners. CONCLUSIONS: Conventional pressure-measuring devices used in compression therapy are not designed for the user's comfort and convenience. The use of flexible and stretchy pressure sensors (e-skin) provides good biocompatibility, conformability, and comfort and when integrated with near-field communication technology could address the drawbacks of current pressure-measuring devices.

In Vitro Characterization of Pressure Redistribution Among Commercially Available Wound Dressings.

OBJECTIVE: Recent clinical evidence has suggested that certain wound dressings may play a significant role in protocols to prevent or reduce pressure injury (PI) in patients at risk by modifying the pressure, friction, and shear forces that can contribute to PI. The aim of this study was to investigate the pressure reduction properties of commercially available wound dressings in vitro. METHODS: Using a standardized protocol (1.7 kg, 7.5-cm sphere), testing was performed in a controlled environment by the same clinician using a pressure mapping device (XSENSOR LX205; XSENSOR Technology Corporation, Calgary, Alberta, Canada) to measure and compare the pressure mitigation properties in a variety of wound dressings. RESULTS: A total of 13 different commercially available dressings were tested in triplicate for changes in pressure redistribution as compared with the control. One dressing demonstrated the greatest reduction of pressure forces (OxyBand PR; 50.33 ± 1.45 mm Hg) compared with the control (302.7 ± 0.33 mm Hg) and the greatest surface area of all the study dressings tested. There was a negative correlation (R2 = 0.73) between the average pressure distribution of a wound dressing and its contact area. Further, the peak pressure for OxyBand PR (P ≤ .05) was significantly different from all other tested dressings. CONCLUSIONS: One dressing (OxyBand PR) provided superior pressure redistribution and significantly reduced peak pressure in this study when compared with currently available standard foam and silicone dressings that are marketed for the purpose of PI prevention.

Risk Factors of Endotracheal Intubation-Related Pressure Injury among Patients Admitted to the ICU.

OBJECTIVE: To investigate the characteristics and risk factors of endotracheal intubation-related pressure injury (EIRPI) in patients admitted to the ICU and provide a basis for EIRPI prevention and treatment. METHODS: A total of 156 patients with endotracheal intubation who were admitted to ICU at a first-class hospital from January to December 2018 were enrolled in this study. Investigators collected and analyzed data and outcomes such as patient characteristics (demographic and clinical), endotracheal catheter-related factors, and the assessment and features of pressure injuries. RESULTS: The incidence of EIRPI was 23.7%. The most commonly affected site was the lip (76.7%). The incidence was affected by endotracheal intubation types, endotracheal catheter indwelling time, subglottic suction, catheter fixation, and fixator types (P < .05). In addition, the moisture, mobility, and friction/shear Braden subscale scores were also correlated with the incidence of pressure injury (P < .05). Long endotracheal catheter indwelling time, the use of catheters with subglottic suction, high Braden moisture subscale score, low Braden mobility subscale score, and low Braden friction and shear subscale scores were predictive factors for EIRPI (P < .05). CONCLUSIONS: Patients in the ICU are at higher risk of developing EIRPI. Early identification of risk factors and timely intervention are the keys to preventing EIRPI.

Angiosomal Vascular Occlusions, Deep-Tissue Pressure Injuries, and Competing Theories: A Case Report.

ABSTRACT: Compression of the soft tissue between a support surface and a bony prominence has long been the accepted primary mechanism of pressure injury (PrI) formation, with the belief that said compression leads to capillary occlusion, ischemia, and tissue necrosis. This explanation presupposes an "outside-in" pathophysiologic process of tissue damage originating at the local capillary level. Despite advances in prevention protocols, there remains a stubbornly consistent incidence of severe PrIs including deep-tissue injuries, the latter usually evolving into stage 4 PrIs with exposed bone or tendon. This article presents just such a perioperative case with the aim of providing further evidence that these more severe PrIs may result from ischemic insults of a named vessel within specific vascular territories (labeled as angiosomes). Pressure is indeed a factor in the formation of severe PrIs, but these authors postulate that the occlusion occurred at the level of a named artery proximal to the lesion. This vascular event was likely attributable to low mean arterial pressure. The authors suggest that the terminology proposed three decades ago to call both deep-tissue injuries and stage 4 PrIs "vascular occlusion pressure injuries" should be the topic of further research and expert consensus.

Brief intermittent pressure off-loading on skin microclimate in healthy adults - A descriptive-correlational pilot study.

AIM: This study examined microclimate changes to the skin as a result of pressure over a 1 h period. The results were compared to skin parameter results following brief consecutive off-loading of pressure-prone areas. DESIGN: A descriptive-correlational pilot study was undertaken. METHOD: A convenience sample of 41 healthy adults aged 18-60 years was recruited. Participants engaged in four 1 h data collection sessions. The sessions were conducted in both semi-recumbent and supine positions. Measures of erythema, melanin, stratum corneum hydration, and skin temperature were taken at pressure-prone areas at baseline and after 1 h in an uninterrupted method (continuous pressure-loading) and every 10 min in an interrupted method (brief off-loading). The Corneometer and Mexameter (Courage + Khazaka Electronics GMbH, 2013) and Exergen DermaTemp DT-1001 RS Infrared Thermographic Scanner (Exergen Corporation, 2008) provided a digital appraisal of skin parameters. Intraclass correlation coefficients (ICC) were calculated to indicate test-retest reliability and absolute agreement of results between the two methods. RESULTS: Strong agreement between the interrupted and uninterrupted method was observed with ICCs ranging from 0.72 to 0.99 (supine) and 0.62-0.99 (semi-recumbent). Endpoint measures tended to be higher compared to baseline measures for all skin parameters. Differences in skin parameters results by anatomical location were evident particularly for erythema and stratum corneum hydration; the elbows and heels yielded lower scores compared to the sacrum. Erythema had the most variation across methods. The supine and semi-recumbent positions had negligible effect on measured skin parameters. CONCLUSIONS: Minimal variation between skin parameter results indicates that brief off-loading in the interrupted method did not significantly change the outcomes; minor shifts in positioning do not alter changes to the skin from pressure. Skin parameters varied by anatomical location and changed over a 1 h period of pressure-loading. RELEVANCE TO CLINICAL PRACTICE: Biophysical techniques may be able to assist accurate assessment of skin microclimate and skin colour. As brief off-loading (interruptions) to enable skin parameter measurement does not alter skin readings, researchers can proceed with some confidence regarding the use of this protocol in future studies assessing skin parameters. This study data provides a library of cutaneous changes at pressure-prone areas of healthy adults and is expected to inform innovative approaches to pressure injury risk assessment.

Characterisation of an ischemia reperfusion model for the formation of a stage I pressure ulcer in mouse skin.

Pairs of magnets were applied to the loose skin on the backs of mice in order to cause ischemia for periods of 1.5, 2, 2.5 and 3 h followed by reperfusion. We found 1.5 h of ischemia resulted in the most reliable outcome of blanched skin but no redness or skin breakdown. Histological analysis at 4 h of reperfusion showed, in the centre of the insult, condensed nuclei in the epidermis and sebaceous glands with a build up of neutrophils in the blood vessels, and a reduction in the number of fibroblasts. At 24 h, spongiosis was seen in the epidermis and pockets of neutrophils began to accumulate under it, as well as being scatted through the dermis. In the centre of the insult there was a loss of sebaceous gland nuclei and fibroblasts. Four days after the insult, spongiosis was reduced in the epidermis at the edge of the insult but enhanced in the centre and in hair follicles. Leukocytes were seen throughout the central dermis. At 8 days, spongiosis and epidermal thickness had reduced and fibroblasts were reappearing. However, blood vessels still had leukocytes lining the lumen. The gap junction protein connexin 43 was significantly elevated in the epidermis at 4 h and 24 h reperfusion. Ischemia of 1.5 h generates a sterile inflammatory reaction causing the loss of some cell types but leaving the epidermis intact reminiscent of a stage I pressure ulcer.

Backrest elevation in the semi-lateral position: Case of a sacral pressure ulcer with undermining formation.

Backrest elevation for a patient with a sacral-coccygeal pressure ulcer is necessary in certain situations, particularly to enable the patient to take meals. Deep pressure ulcers with undermining formations affect patients and create challenges for caregivers. The procedure of backrest elevation potentially worsens the pre-existing sacral-coccygeal pressure ulcers with undermining formations. Here, we report a Case of the clinical care of a patient using a simple approach for backrest elevation that minimizes additional injury to the existing sacral pressure ulcer covered with granulation tissue. In this case, we performed the backrest elevation in the semi-lateral position. After the backrest elevation, the patient was repositioned to the supine position to take a meal. The supine position was allowed at any time except during backrest elevation. The pressure ulcer of the patient improved rapidly using the combined treatment of our positioning approach and appropriate topical ointments. This practical approach may be effective for some patients as it potentially decreases the effect of shear force. The rationale for this approach can be explained by the mechanism of the undermining formation outlined in our experimental study using a pressure ulcer model mounted to a phantom. Although we used this position for patients with sacral-coccygeal pressure ulcers, this simple approach may also be considered for other patients based on our proposed pathogenesis of undermining formations.

Evaluation of interface pressure and temperature management in five wheelchair seat cushions and their effects on user satisfaction.

BACKGROUND: Factors such as the manufacturing materials, shape or even the mechanical and thermal response of sitting Pressure Redistribution Support Surfaces (PRSS) can be potential contributors to pressure ulcers. However, few studies have compared a number of characteristics of the most frequently used devices. OBJECTIVE: To compare three potential contributors to pressure ulcers in five commercial PRSS: pressure redistribution, temperature and perceived comfort. METHOD: Study with a cross-over randomized design in healthy volunteer participants. Data was collected in a temperature and relative humidity controlled environment. To assess thermal response, the temperature (Flir-E60) of the region of interest was captured before and after use of each PRSS for further analysis. The region of interest was the gluteal zone. To assess the pressure redistribution a pressure mat (XSensor®) was used between the 5 cushion and each study participant using a standardized method. Finally, a subjective perception questionnaire recorded comfort, adaptability and thermal sensation parameters. Data analysis levels of significance were set at 0.05. RESULTS: A total of 22 participants completed the assessments. There were no statistically significant differences in baseline temperatures between PRSS (>0.05). Pressure redistribution analysis showed significant differences between all PRSS in all variables evaluated except in the maximum and peak pressure index al sacrum. The subjective assessment suggested no major user-perceived differences between PRSS. CONCLUSION: Seat cushions made of open cell polyurethane foam blocks of variable hardness and the horseshoe cushion (also open cell polyurethane foam) seem to provide a more effective pressure relief characteristic than those injected with polyurethane foam and gel in most of the studied pressure variables. However, the cushions provide similar thermal response and perceived comfort.