Compartment Pressure Research Articles

Acute post sleeve surgery bleeding as rare cause of acute renal failure: a case report

BackgroundBariatric surgeries have been considered as one of the most important treatment procedures in recent years. Being aware of the side effects of this surgery will lead to better results after the surgery.Case presentationA 37-year-old Iranian male patient presented one day after sleeve surgery with symptoms of weakness, lethargy, and shortness of breath, which hospitalization and workup to were done to rule out pulmonary embolism. Because of the high creatinine and anuria, we couldn’t perform computed tomography angiography. A bedside ultrasound was done for the patient and showed a mild to moderate amount of fluid around the spleen and some blood clots. Due to the progressive clinical findings and suspected internal bleeding, the patient was a candidate for laparoscopic revision procedure. Gradually, after performing the surgery, removing the blood clot and reducing the compressive effect of that on the inferior verna cava which was the main reason of renal failure, the patient was able to urinate afterwards and was discharged in good general condition.ConclusionSurgeons should be aware of the management of rare surgical complications after bariatric surgeries. To be best of our knowledge, this was the first case report of a patient with acute renal failure after bariatric surgery and the rare cause of clot compression on inferior vena cava and raised abdominal compartment pressure.

Paper 23: Taking the Load Off: Effect of Varus Producing Distal Femoral Osteotomy and High Tibial Osteotomy on Compartment Pressures and Contact Area in Varying Stages of Knee Flexion

Objectives: Study Objective: Evaluate mean contact area, mean contact pressure, and peak contact pressure in the medial and lateral compartment of the knee following varus producing high tibial osteotomy and distal femoral osteotomy in varying states of knee flexion (0*, 30*, 60*, 90*). Background: Genu valgum causes mechanical pressure to be transferred to the lateral compartment. In patients with valgus alignment and a diseased lateral compartment, both lateral opening wedge distal femoral osteotomy (DFO) and high tibial closing wedge osteotomy (HTO) can be used to unload a diseased lateral compartment of the knee. To the best of our knowledge, there are no biomechanical studies investigating how a DFO and HTO affect lateral compartment contact pressure and area in varying states of flexion. Prior anatomic studies have shown that, in valgus knees, the tibial wear is posterior. Additional, biomechanical studies have indicated that DFO exerts the greatest effect in full extension but it’s effect is decreased as flexion angle rises. Hypothesis: Medial closing wedge high tibial osteotomy will significantly decrease contact area, mean contact pressure and peak contact pressure in the lateral knee compartment through knee flexion to a greater extent compared to lateral opening wedge distal femoral osteotomy. Methods: Lateral opening wedge DFO and medial closing wedge HTO was performed, correcting a mean of 8°, in 10 cadaveric knees using plate fixation. Tibio- femoral contact pressure of the medial and lateral compartment was measured in 0°, 30°, 60°, and 90° of knee flexion before and after osteotomy using thin electronic sensors (K-scan Model 4000, 1500 psi; Tekscan Inc, South Boston, MA) and load applied through an Instron device (Instron, Norwood, MA). Peak contact pressure (PCP), average contact pressure (ACP), and contact area (CA) were measured for each condition. Mixed-effects regression analyses were used to compare the change in variables before and after osteotomy and between flexion angles. Results: The lateral ACP was significantly decreased in the HTO state when compared to native in 30° (p=0.015), 60° (p=0.0199), and 90° (p<0.0001) of flexion. The lateral ACP was also significantly decreased in the HTO state when compared to the DFO state in 60° (p=0.0093) and 90° of flexion (p<0.0001). Following DFO, the lateral ACP returned to that of the native state in 60° (p=1.000) and 90° (p=1.000) of flexion. The medial ACP was significantly increased when compared to both the native and HTO state in 60° (p<0.001; p=0.015) and 90° (p<0.0001; p=0.0435) of flexion. Conclusions: With varus corrections of <10°, medial closing HTO is more effective at unloading the lateral compartment than lateral opening DFO. This effect is amplified as the knee flexion angle increases.

Compartment Syndrome following Intramedullary Nail Fixation in Closed Tibial Shaft Fractures.

Compartment syndrome complicating intramedullary nailing of closed tibia fractures has been described as early as the 1980s, but currently remains less described in literature compared to compartment syndrome directly following trauma. This study aims to review this potentially disabling complication and highlight the importance of timely diagnosis and management of compartment syndrome following fracture fixation, not just after fracture itself, via a review of three cases. A retrospective study of a series of three cases was conducted. The type of fracture, wait time to fixation, surgery duration, reaming, size of nail implant used, tourniquet time, and surgical technique were recorded. Time to diagnosis of compartment syndrome, compartment pressure if available, extent of muscle necrosis, reconstructive procedures performed, and post-operative complications were analysed. The three cases following high-energy trauma from road traffic accidents presented from January to May 2010. Compartment syndrome was diagnosed clinically for all cases, between one to six days post-operatively and supported by elevated compartment pressure measurements in two of the three cases. This study advocates thorough clinical monitoring and maintaining strong clinical suspicion of compartment syndrome in patients even after intramedullary nail fixation of tibial shaft fractures to achieve timely limb-salvaging intervention. While intercompartmental pressure can be used to aid in diagnosis, we do not advise using it in isolation to diagnose compartment syndrome. Tendon transfer improves functional mobility and provides a good result in patients with severe muscle damage, while skin grafting sufficient in patients with minimal muscle damage.

Research on the calculation method of penetration resistance of bucket foundation for offshore wind turbines

The cost of foundations for offshore wind turbines constitutes approximately 35% of the total cost of an offshore wind farm. The bucket foundations show significant potential due to their superior transportation and installation efficiencies compared to pile foundations, leading to potential cost savings for the foundation of up to 30%. For a bucket foundation to be installed successfully, the penetration resistance must be predicted. However, there is currently a lack of clarity on how to select a suitable calculation method for penetration resistance based on known geological parameters to guide construction. In order to evaluate the current methods of calculation for bucket foundation penetration resistance, this study combines theoretical calculation methods with two sets of practical measurement data from the field. The calculation methods of penetration resistance for bucket foundation are first reviewed and categorized. The applicability range of each method and the parameters needed for calculation are given. Next, according to the measured data in the process of penetration of bucket foundation on site, the evolution of compartment pressure, tilt angle, resistance and required suction in the process of penetration are analyzed. Finally, the reviewed methods are compared to the results of two practical projects in order to analyze the differences between them and make recommendations for the calculation technique. The findings can be used as a guide for calculating the bucket foundation's penetration resistance in complex geological conditions.

Estimation of Physiologic Pressures: Invasive and Non-Invasive Techniques, AI Models, and Future Perspectives.

The measurement of physiologic pressure helps diagnose and prevent associated health complications. From typical conventional methods to more complicated modalities, such as the estimation of intracranial pressures, numerous invasive and noninvasive tools that provide us with insight into daily physiology and aid in understanding pathology are within our grasp. Currently, our standards for estimating vital pressures, including continuous BP measurements, pulmonary capillary wedge pressures, and hepatic portal gradients, involve the use of invasive modalities. As an emerging field in medical technology, artificial intelligence (AI) has been incorporated into analyzing and predicting patterns of physiologic pressures. AI has been used to construct models that have clinical applicability both in hospital settings and at-home settings for ease of use for patients. Studies applying AI to each of these compartmental pressures were searched and shortlisted for thorough assessment and review. There are several AI-based innovations in noninvasive blood pressure estimation based on imaging, auscultation, oscillometry and wearable technology employing biosignals. The purpose of this review is to provide an in-depth assessment of the involved physiologies, prevailing methodologies and emerging technologies incorporating AI in clinical practice for each type of compartmental pressure measurement. We also bring to the forefront AI-based noninvasive estimation techniques for physiologic pressure based on microwave systems that have promising potential for clinical practice.

Effects of Lateral Opening-Wedge Distal Femoral Osteotomy on Meniscal Allograft Transplantation: A Biomechanical Evaluation

Background: Lateral meniscal deficiency with valgus malalignment increases the rate of lateral compartment osteoarthritis. Lateral meniscal allograft transplantation (LMAT) with a concomitant varus-producing opening-wedge distal femoral osteotomy (DFO) is an option yet to be evaluated biomechanically. Purpose/Hypothesis: The purpose of this study was to clarify the biomechanical effects of the realignment procedure in the setting of LMAT. We hypothesized that (1) given the dependence of the lateral compartment on the lateral meniscus, a DFO and increasing degrees of varus would be insufficient to restore lateral compartment pressures to normal from a lateral meniscus-deficient state, and that (2) LMAT would restore lateral compartment pressures to the intact state while DFO would decrease lateral compartment pressures for any given state of the meniscus. Study Design: Controlled laboratory study. Methods: Ten cadaveric knees underwent opening-wedge varus-producing DFO secured by an external fixator. Anatomic alignment was standardized to 6° of mechanical valgus, and each joint was tested in full extension. Submeniscal placement of thin film pressure sensors allowed for the recording of contact pressure, peak contact pressure, and contact area. The specimens were loaded on a biaxial dynamic testing machine with loading angles between 9° valgus and 6° varus of mechanical alignment. Conditions tested included intact meniscus, meniscal deficiency, and meniscal transplantation. Results: Isolated varus-producing DFO to 6° in the meniscus-deficient state failed to restore joint pressures and contact areas to the intact state, with significant changes in mean contact pressure (175%), mean peak contact pressure (135%), and contact area (–41%) (all P < .05 vs intact), while LMAT restored all outcome measures (all P > .05 compared with intact). After LMAT, every additional 1° of DFO correction contributed to a decrease in the mean contact pressure, peak pressure, and contact area of 5.6% (–0.0479 N/mm2), 5.9% (–0.154 N/mm2), and 1.4% (–6.99 mm2) for the lateral compartment and 7.3% (+0.034 N/mm2), 12.6% (+0.160 N/mm2), and 4.3% (+20.53 mm2) for the medial compartment, respectively. Conclusion: Isolated DFO was inadequate to restore load distribution in meniscus-deficient knees, while concomitant LMAT restored near normal forces and improved the lateral compartment biomechanical profile. Clinical Relevance Our findings support the concomitant use of LMAT and varus-producing DFO in the setting of lateral meniscal deficiency with valgus malalignment. This study provides tools for the orthopaedic surgeon to individualize the correction for each patient.

The Pressure Is Rising: Evaluation and Treatment of Chronic Exertional Compartment Syndrome.

Chronic exertional compartment syndrome is a condition that typically affects athletic/active individuals. Chronic exertional compartment syndrome predominantly affects the lower leg; however, there are cases involving the hand, forearm, foot, and thigh. The signs and symptoms of chronic exertional compartment syndrome are severe pain, tightness, cramping, muscle weakness, and paresthesias during participation in exercise. Dynamic intramuscular compartmental pressure (preexertion and postexertion) is the standard diagnostic test. Although other imaging modalities, such as radiography, ultrasound, and magnetic resonance imaging are typically incorporated to rule out other pathologies. In addition, these modalities are being utilized to limit invasiveness of the diagnostic experience. Initial care commonly involves conservative treatment, such as physical therapy, modifications of patient's exercise technique, foot orthoses, and various procedures over a period of 3 to 6 months. Recalcitrant cases may be referred for surgical intervention (fasciotomy), which has inconclusive head-to-head data with conservative management with regard to return to prior sport and specific activity level.

Chronic compartment-syndrome of the lower limb: modern strategies for diagnosis and treatment

A review of the literature is presented, including data on the incidence, pathophysiology, and clinical picture of patients with chronic compartment syndrome (CCS) of the lower extremities. Chronic exercise compartment syndrome (CECS) is characterized by pain with repetitive exertion and increased intracompartmental pressure affecting the lower extremities in physically active patients. In severe chronic venous insufficiency of the lower extremities, chronic venous compartment syndrome (CVCS) develops, which is fundamentally different from previously known clinical pictures. Progressive dermatolipofasciosclerosis and cicatricial destruction of the fascia of the leg in patients with C4b-C6 clinical classes according to CEAP affect the pressure in the muscle-fascial compartments at each step. In severe cases, this leads to significant changes in the muscles, accompanied by chronic ischemia associated with necrosis and glycogen deficiency. The analysis of various diagnostic methods, conservative treatment and methods for performing surgical decompression of the CCS was carried out. The lack of a clear pathophysiology for CECS and CVCS complicates the diagnosis and treatment of this condition. Diagnosis of calf CCS is still based on pressure testing in the musculofascial compartments of the calf using the Pedowitz criteria, however standard procedures for this, including patient position, static or dynamic movements, muscles and equipment tested, are not agreed upon. In patients with CCS, if conservative treatment is ineffective, fasciotomy of the affected parts of the lower leg is the method of choice. Various techniques for fasciotomy of the lower leg include the traditional open fasciotomy, the semi-closed technique with one or more incisions, the minimally invasive technique using endoscopic compartment release, and the use of ultrasound guidance. Fasciectomy of the lower leg to correct CVCS is performed mainly for recurrence of trophic ulcers after shave therapy, severe calcification of the lower leg tissues and for the treatment of deep transfascial necrosis. Randomized, blinded, controlled trials are needed to further expand our knowledge of the diagnosis and treatment of CCS.

Lateral Compartment Syndrome From Inversion Injury.

A 17-year-old male presented for the evaluation of right calf pain after an inversion ankle sprain sustained while playing soccer 24hours prior. On exam, he exhibited swelling and tenderness to palpation over his right calf, mild first web space numbness, and compartment pressures <30mmHg. Magnetic resonance imaging was significant for findings of lateral compartment syndrome (CS). Upon admission, his exam worsened, prompting an anterior and lateral compartment fasciotomy. Intraoperative findings were significant for lateral CS, with findings of avulsed, nonviable muscle with associated hematoma. Postoperatively the patient had mild foot drop, which improved with physical therapy. Lateral CS rarely develops from an inversion ankle sprain. This presentation of CS is unique due to its mechanism, delayed clinical presentation, and limited signs of CS. Providers should maintain a high index of suspicion for CS in patients with this injury complex and continued pain beyond 24hours without signs of ligamentous injury.

The Use of an 18-Gauge Needle to Measure Compartment Pressures: a Case Report

The Use of an 18-Gauge Needle to Measure Compartment Pressures: a Case Report

Medial Varus Proximal Tibial Resection is Superior to Pie-Crusting of the Medial Collateral Ligament During Primary Total Knee Arthroplasty

BackgroundMedial varus proximal tibial (MPT) resection or soft tissue releases (STRs) of the medial collateral ligament (MCL) in the form of pie-crusting can be performed to achieve a balanced knee in a varus deformity. Studies comparing the 2 modalities have not been addressed within the literature. Therefore, the aims of this study were to assess the following: (1) compartmental changes between the 2 methods and (2) changes in patient-reported outcome measurements. MethodsUsing our institution’s total joint arthroplasty registry, patients who underwent primary total knee arthroplasty from January 1, 2017, to December 31, 2019, were identified. The MPT resection and STR patients were 1:1 matched with baseline parameters yielding 196 patients. Outcomes of interest included: changes in compartmental pressures at 10, 45, and 90° degrees and change to the Short-Form 12, Western Ontario and McMaster Universities Osteoarthritis Index, and Forgotten Joint Scores (FJSs) at the 2-year follow-up period. A P value less than .05 was used as our threshold for statistical difference. ResultsThe MPT resection led to significant reductions in compartmental pressures at 10° [43 versus 19 pounds (lbs.), P < .0001], 45° (43 versus 27 lbs., P < .0001), and 90° degrees (27 versus 16 lbs., P < .0001) compared to STR. MPT resection also had significantly improved Short-Form 12 (47 versus 38, P < .0001), Western Ontario and McMaster Universities Osteoarthritis Index (9 versus 21, P < .0001), and Forgotten Joint Score (79 versus 68, P = .005). ConclusionBone modification was superior to pie-crusting of the MCL in achieving consistent pressure balancing and improved outcomes. The investigation can guide surgeons on the preferred method to achieve a well-balanced knee.

Collateral Ligament Tension and Balance Alone Does Not Ensure Improved Outcome After Total Knee Arthroplasty

BackgroundIt is hypothesized that suboptimal soft tissue and collateral ligament balance is a cause of patient dissatisfaction following total knee arthroplasty (TKA). This analysis examined the association between compartment pressures during TKA and patient-reported outcome measurements (PROMs). MethodsThis single-institution, retrospective cohort study of prospectively collected compartment pressure data measured during TKA comprised 145 patients who underwent surgery between 2015 and 2021 and completed 1-year follow-up PROMs. The primary outcome included pressures, in pounds (lbs), of the medial and lateral compartments in extension (5°), mid-flexion (45°), and flexion (90°), and associated PROMs. The difference been the 1-year and preoperative PROMs was used to separate the top 25% from the bottom 75% performers. Pressures were compared using Student's T-tests and multivariate linear regressions, while controlling for preoperative deformity. A subgroup analysis of the most popular implant was performed. ResultsHigher medial compartment pressures were seen in our total cohort (Knee Society Score (KSS) mid-flexion 24 versus 18 lbs, P = .03, flexion 24 versus 17 lbs P = .01) and within our subgroup analysis (Short form- Mental (SF-M) extension 32 versus 21 lbs P = .01, KSS mid-flexion 27 versus 16 lbs P = .005, extension 31 versus 20 lbs P = .003). This trend persisted in the subgroup analysis when controlling for preoperative deformity (KSS extension +16.22 lbs P ≤ .001, mid-flexion +17.6 lbs. P = .001, and flexion +9.2 lbs, P = .005). ConclusionSeveral groups demonstrated higher medial versus lateral pressures. However, this pattern was not consistent across PROMs, suggesting that compartment pressures at the time of TKA are an important factor but not the sole predictor of patient satisfaction.

Paresthesia Is Predictive of Symptom Recurrence After Fasciotomy for Exertional Compartment Syndrome of the Leg.

Exertional compartment syndrome (ECS) is an underdiagnosed cause of lower extremity pain among athletes. The condition can be managed operatively by fasciotomy to relieve excess compartment pressure. However, symptom recurrence rates after fasciotomy are considerable, ranging from 3% to 17%. Leg paresthesia and its distribution during ECS episodes would be a significant predictor of outcomes after fasciotomy. Retrospective cohort study. Level 4. We conducted a retrospective chart review of patients who underwent fasciotomy for ECS at our center from 2010 to 2020 (institutional review board no. 21-00107). We measured postoperative outcomes including pain frequency and severity, Tegner activity level, and return to sport. Significant predictors of outcomes were identified using multivariable linear and logistic regression. P values <0.05 were considered significant. A total of 78 legs (from 42 male and 36 female participants) were included in the study with average follow-up of 52 months (range, 3-126 months); 33 participants (42.3%) presented with paresthesia. Paresthesia was an independent predictor of worse outcomes, including more severe pain at rest (P = 0.05) and with daily activity (P = 0.04), reduced postoperative improvement in Tegner scores (P = 0.04), and lower odds of return to sport (P = 0.05). Those with paresthesia symptoms in the tibial nerve distribution had worse outcomes than those without paresthesia in terms of preoperative-to-present improvement in pain frequency (P < 0.01), pain severity at rest (P < 0.01) and with daily activity (P = 0.04), and return to sport (P = 0.04). ECS patients who present with paresthesia have worse pain and activity outcomes after first-time fasciotomy, but prognosis is worst among those with tibial nerve paresthesia. Paresthesia among ECS patients is broadly predictive of more severe recurrent leg pain, reduced activity level, and decreased odds of return to sport after fasciotomy.

Measurement of the gluteal compartment pressures: A cadaveric study describing safety and reproducibility of two methods

IntroductionGluteal compartment syndrome is an uncommon entity and physicians may use intracompartmental pressure measurements for confirmation of the clinical diagnosis, or in cases where the physical exam is indeterminate. However, there is a paucity of literature describing a safe and reproducible technique to measure gluteal intracompartmental pressures during the diagnosis of gluteal compartment syndrome. The purpose of this cadaveric study is to evaluate the sole previous technique described in the literature to measure gluteal intracompartmental pressures and provide a modified technique which can be safely and reliably utilized clinically. MethodsA cadaveric study with three phases was performed in 16 gluteal regions in 8 cadavers. In the first phase, the previously described technique was assessed. In the second phase, a modified set of techniques was created and evaluated. In the third phase, inter-user reliability of the modified set of techniques was assessed and calculated using Cohen's ĸ coefficient. In all three phases, methylene blue was injected through pressure monitoring needles into the gluteus maximus (GMax), gluteus medius/minimus (GMM), and the tensor fascia lata (TFL) compartments. Following dissection, rate of successful penetration into each targeted compartment and distance from the neurovascular structures was recorded. ResultsThe previously described set of techniques was found to be variable. The modified set of techniques was effective, successfully reaching the GMax, GMM, and TFL compartments in 100%, 100%, and 81% of attempts, respectively. Inter-user reliability was excellent (ĸ = 1) for the techniques to reach both the GMax and GMM compartments, and moderate (ĸ = 0.54) for the technique to reach the TFL compartment. Within the GMax, the pressure monitoring needle was at a mean of 5.4±0.6 cm, 4.1±0.7 cm, 6.4±0.5 cm from the sciatic nerve (SN), superior gluteal nerve (SGN), and inferior gluteal nerve (IGN), respectively. Within the GMM, the pressure monitoring needle was at a mean of 9.7±1.4 cm, 7.4±1.3 cm, 11.1±1.7 cm from the SN, SGN, and IGN, respectively. ConclusionThe modified set of techniques presented allows the three gluteal compartments to be safely and reproducibly reached to measure intracompartmental pressures during the diagnosis of gluteal compartment syndrome.

Shin Splint: A Review.

Medial tibial stress syndrome (MTSS), usually referred to as "shin splints," is a common overuse injury of the lower extremities affecting a large percentage of athletes. A variety of factors can lead to shin splints, including overtraining, poor footwear, muscular imbalances at the ankle, overtight or weak triceps surae muscles, imbalances at the thoracolumbar complex, and a body mass index (BMI) above 30. Injuries present with diffuse palpable pain that is often described as a dull ache following exercise. The pain is often alleviated by resting. Often, athletes complain of tenderness along the posteromedial edge of the tibia and pain along the middle to distal third of the posteromedial border of the tibia following an exercise session. The pain caused by a shin splint should be categorized according to its location and cause, such as lower medial tibial pain caused by periostitis or upper lateral tibial pain caused by raised compartment pressure. In order to prevent MTSS or shin splints, it is important to avoid excessive stress. The main objectives of shin splint treatment are to relieve pain and to enable the patient to return to normal activities without pain. To prevent shin splints, repetitive stress should be avoided. In this paper, we review what is known about the pathophysiology of shin splintsyndrome, present evidence regarding risk factors associated with shin splints, assess the effectiveness of prevention strategies, and make recommendations for prevention. The purpose of this study is to assess the effectiveness of interventions to prevent shin splints.

Toward Redox-Free Reverse Electrodialysis with Carbon-Based Slurry Electrodes.

Clean and renewable salinity gradient energy can be harvested using reverse electrodialysis (RED). The electrode system is an essential part to convert ionic current into electrical current. In this study, a typical 0.10 × 0.10 m2 RED stack with a cross-flow configuration was used to test carbon-based slurry electrodes (CSEs) to replace the usual redox solutions, like hexacyanoferrate, to enhance the RED process' sustainability, stability, and economic value. Six different slurry compositions comprising activated carbon, carbon black, and graphite powder were tested. The CSE characteristics were systematically studied by measuring viscosity, electrode compartment pressure drop, maximum current density, stability, and performance of power density and energy efficiency. Using a single membrane configuration, the CSE ran continuously for 17 days with a stable output. The application of CSEs for RED, with artificial seawater and river water, using mixing activated carbon and carbon black at a total concentration of 20 wt %, resulted in the best performance with a net power density of 0.7 W·m-2. Moreover, higher current densities up to 350 A·m-2 were tested for ED and shown to be feasible until 150 A·m-2. CSEs show promising versatility for different application modes.

Mechanisms of reduced cerebral blood flow in cerebral edema and elevated intracranial pressure.

A mechanism of elevated intracranial pressure (ICP) in cerebral edema and its effects on cerebral blood flow (CBF) are presented in this paper. To study and demonstrate these effects, a mathematical model of intracranial hydrodynamics was developed. The model simulates the intracranial hydrodynamics and the changes that occur when cerebral edema predominates. To account for an edema pathology, the model includes resistances to cerebrospinal fluid (CSF) and interstitial fluid (ISF) flows within the parenchyma. The resistances change as the intercellular space becomes smaller due to swelling of brain cells. The model demonstrates the effect of changes in these resistances on ICP and venous resistance to blood flow by accounting for the key interactions between pressure, volume, and flow in the intracranial compartments in pathophysiological conditions. The model represents normal intracranial physiology as well as pathological conditions. Simulating cerebral edema with increased resistance to cerebral ISF flow resulted in elevated ICP, increased brain volume, markedly reduced ventricular volume, and decreased CBF as observed in the neurointensive care patients. The model indicates that in high ICP values, alternation of the arterial-arteriolar resistance to flow minimally affects CBF, whereas at low ICP they have a much greater effect on CBF. The model demonstrates and elucidates intracranial mechanisms related to elevated ICP.NEW & NOTEWORTHY Study goal was to elucidate the role of "bulk flow" of ISF through brain parenchyma. A model was developed to simulate fluid shifts in brain edema, ICP elevation, and their effect on CBF. Bulk flow resistance affected by edema elevates ICP and reduces CBF. Bulk flow affects transmural pressure and volume distribution in brain compartments. Changes in bulk flow resistance result in increase of venous resistance to flow and decrease in CBF.

Early assessment of extremity compartment syndrome by biochemical markers in a rat model.

This experimental study aimed to define a biochemical marker that will enable early diagnosis of acute compartment syndrome (ACS) of extremities, a mortal condition that occurs due to trauma. A total of 15 Wistar rats were included in the study in which saline infusion technique, a clinically compatible ACS model, was applied. After the rats were anesthetized with ketamine-xylazine, the in-compartment pressure of the hind limb was slowly increased with saline delivered through the angiocatheter, and after reaching the target compartment pressure, the pressure level was kept with a rubber tourniquet. The in-compartment pressure level was continuously monitored with a pressure transducer. The rats were divided into three groups. No intervention was applied to the control group (CG) (n = 3). In study group 1 (SG1) (n = 6), ACS was created using the saline infusion technique, keeping the in-compartment pressure between 30 and 40 mmHg for 45 min. In study group 2 (SG2) (n = 6), ACS was created using the saline infusion technique, keeping the in-compartment pressure between 30 and 40 mmHg for 90 min. Fasciotomy was performed on all rats. Tissue samples were obtained for histopathological examination and blood samples for biochemical analysis. Total oxidant status (TOS) (p = 0.004), ischemia-modified albumin (IMA) (p = 0.030), aspartate transferase (AST) (p = 0.003) and neopterin (p = 0.012) levels differed significantly between groups in the early period of muscle ischemia. In fact, TOS levels differed significantly between the groups even in the cellular phase where signs of ischemia were not observed (p = 0.048, p = 0.024). According to histopathological evaluation, there was no significant difference between the groups. TOS can be detected in the early reversible stage of ischemia, when the histopathological findings of ACS do not occur.

Study protocol for a multicenter randomized controlled pilot study on decompressive laparotomy vs. decompressive craniectomy for intractable intracranial pressure after traumatic brain injury: The SCALPEL study

IntroductionDecompressive craniectomy (DC) is the ultimate intervention to lower intracranial pressure (ICP) following severe traumatic brain injury (TBI). However, this intervention is associated with considerable adverse events and a higher proportion of survivors with poor functional outcomes. Research questionIn a multicompartment system ICP is associated with intraabdominal pressure (IAP) due to cerebral venous outflow from the brain. This is the rationale for decompressive laparotomy (DL) to control ICP after TBI as reported by experimental and retrospective clinical data. The safety profile of DL is superior to DC. This study aims to randomly assign patients with intractable high ICP after severe TBI to DL or DC. Material and methodsAmong other inclusion criteria, ICP must be above 20 mmHg (1–12 h) despite sedation and all other measures according to current guidelines. The primary outcome is the Extended Glasgow Outcome Scale assessed after twelve months. Further secondary outcome measures are compartmental pressure values, complications, etc. After 20 initial patients, results will be reviewed by the ethics committees and safety monitoring board to decide on the enrolment of 80 additional patients. ResultsThe study is designed to provide not only high-quality prospective data for the first time on this treatment approach, its two-stage design (20 + 80 pts) also provides maximum patient safety. This protocol conforms with the SPIRIT 2013 Statement. Ethics approval was granted by our but also 5 other university ethics committees (registration 473/18S). ConclusionRegistration was performed prior to study initiation in November 2021 (registration number NCT 05115929).

Tibial component rotation alters soft tissue balance in a cruciate retaining total knee arthroplasty

Our aim was to understand whether using different landmarks for tibial component rotation influenced articular contact pressures in a balanced total knee arthroplasty (TKA). Twelve patients underwent TKA (Triathlon CR, Stryker Inc., Mahwah, NJ) and contact pressures were assessed using a wireless sensor. Robotic arm assisted TKA using a functional alignment technique was performed, with balanced gaps between medial and lateral compartments. Compartment pressures were measured with the trial tibial component rotated to Akagi's line and to Insall's axis respectively. Rotating the tibial component to Akagi's line resulted in a significantly greater proportion of knees being balanced and lower contact pressures than when the tibial component was rotated to Insall's axis at 10°, 45° and 90° of flexion (p < 0.05). Medial compartment pressures were significantly increased in 10° of flexion, as were lateral compartment pressures in all positions when the tibial component was aligned to Insall's axis (p < 0.05). The mean difference in rotation observed with the two landmarks was 6.9° (range 4.1–9.1°). Rotational alignment of the tibial component using Akagi's line reduced contact pressures, improved balance and reduced the need for soft tissue release when compared with Insall's axis in robotic arm assisted TKA.