A mathematical model describing the transport and distribution of fluid and plasma proteins between the circulation, the interstitium, and the lymphatics, is formulated for the human. The formulation parallels that adopted by Bert et al.[5] in their model of microvascular exchange in the rat. The human microvascular exchange system is subdivided into two distinct compartments: the circulation and the interstitium. Both compartments are treated as homogeneous and well-mixed. Two alternative descriptions of transcapillary exchange are investigated: a homoporous "Starling Model" and a heteroporous "Plasma Leak Model". Parameters which characterize fluid and protein transport within the two models are determined by a comparison (quantified statistically) of the model predictions with selected experimental data. These data consist of interstitial fluid volumes and colloid osmotic pressures measured as a function of plasma colloid osmotic pressure for subjects suffering from hypoproteinemia. The relationship between this fitting data and the model transport parameters is investigated using a visual "graphical optimization technique" and additionally, in the case of the Starling Model, by use of a non-linear optimization technique. Both the Starling Model and the Plasma Leak Model provide good representations of the fitting data for several alternative sets of parameter values. The ranges of parameter values obtained generally agree well with those available in literature. The fully determined model is used to simulate the transient behaviour of the system when subjected to an intravenous infusion of albumin. All alternative "best-fit" parameter sets determined for both models produce simulations which compare reasonably well with the experimental infusion data of Koomans et al.[42]. The predictions of both models compare favourably not only with the available experimental data but also with the known behavioural characteristics of the human microvascular exchange system. However, no conclusions may be drawn regarding which of the alternative transcapillary transport mechanisms investigated provides the better description of human microvascular exchange, although it appears likely that diffusion of proteins plays a significant role in both. Final model selection and choice of fitting parameters await the availability of more and better microvascular exchange data for humans. Analysis of both the Starling Model and Plasma Leak Model indicates that the microvascular system is capable of regulating the interstitial fluid volume over a fairly wide range of transport parameter values. The important model-predicted passive regulatory mechanisms are tissue "protein washout", which reduces its colloid osmotic pressure,and a low tissue compliance which increases the hydrostatic pressure of the interstitium as it becomes hydrated. It would therefore seem that the human microvascular system can be regarded as a fairly "robust" system when considering its ability to regulate interstitial fluid volume (i.e., small changes in the values of transport parameters, such as the capillary wall permeability, have little effect on the conditions and operation of the system). / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Chronic exertional compartment syndrome (CECS) of the lower leg, defined as a condition with exercise-induced pain due to increased intramuscular pressure (IMP), has previously mainly been described in running athletes, and etiologic factors are poorly described. CECS has not been reported to occur together with other diseases and information about consequences on muscles morphology after treatment with fasciotomy is largely unknown. We investigated etiologic and pathophysiologic aspects to CECS in a consecutive series of 63 patients with exercise-related leg pain and in 17 diabetic patients with symptoms of intermittent claudication but no circulatory insufficiency. Clinical examination, radiography, scintigraphy and IMP measurements at rest and after reproduction of symptoms were done. Patients with CECS were recommended treatment with fasciotomy. Biopsies were taken from the tibialis anterior muscle at time of fasciotomy and at follow-up 1 year later. For comparison muscle samples were taken from normal controls. Enzyme- and immunohistochemical and morphometric methods were used for analysis of muscle fiber morphology/pathology, fiber phenotype composition, mitochondrial oxidative capacity and capillary supply. Thirty-six of the 63 patients fulfilled the criteria for diagnosis of CECS in the anterior tibial compartment. The CECS patients could be divided into different etiologic groups: 18 healthy, 10 with history of trauma against the lower leg, 4 diabetic patients and 4 others. Only 5 of 36 CECS patients were athletes. The results after fasciotomy were good or excellent in 41 of 57 treated legs.  Sixteen of the 17 diabetic patients were diagnosed with CECS, 11 with diabetes type 1 and 5 with type 2. The diabetic patients differed from the other groups with longer symptom-duration, shorter pain-free walking distance, firm and tender lower leg muscles and higher IMP. The postoperative outcome was good or excellent in 15 of 18 treated legs. The muscle biopsies taken at fasciotomy showed frequent histopathological changes including small and large sized fibers, fiber atrophy, internal myonuclei, split fibers, fibrosis, disorganization of mitochondria in contrast to healthy CECS subjects having low muscle capillarization as the main finding. Muscular abnormalities were generally more complex, severe and widespread in diabetic patients. After 1 year, the majority of CECS patients could return to unrestricted physical activity and the histopathological muscle changes were clearly reduced. The muscle fiber size was larger and the muscles contained signs of regeneration and repair. Remaining muscle abnormalities were present mainly in diabetic patients. CECS is a new differential-diagnosis in diabetic patients with symptoms of claudication without signs of vascular disease. A low ability for physical activity, reflected by the signs of both myopathy and neuropathy, indicates that high IMP and circulatory impairment has deleterious effects for the involved muscles. Increased physical activity and normalization of muscle morphology 1 year after treatment shows the benefit of fasciotomy. The more severe clinical and morphological findings in diabetic compared to healthy subjects with CECS indicate differences in the pathogenesis. The unrestricted physical ability after treatment is very important for diabetic patients, since physical activity is an essential part of the therapy of the disease.

Introduction — Hyperkalemia, defined as serum potassium >6.0mmol/L, affects ±6% of people with kidney disease and is a contraindication to surgery due to the perioperative risk of potentially fatal cardiac dysrhythmia (1,2,3). When emergency surgery cannot be avoided, hyperkalemia must be managed perioperatively using a variety of traditional practice patterns which vary in efficacy (3,4,5). We present a case report of successful rapid correction of hyperkalemia in a 67-year- old man with a history of chronic kidney disease who presented to the emergency department for acute compartment syndrome in need of emergent fasciotomy to prevent loss of limb. Methods — Since emergent treatment of hyperkalemia is often managed through a combination of medications with multiple mechanisms of action, we reviewed available related literature in PubMed in order to present this educational case report. Patient Presentation — At the time of presentation, our patient’s serum potassium was 7.7mmol/L, creatinine kinase was 33,160U/L, and an ECG revealed a first-degree AV node block with slight ST depression. Following intubation, as a team of surgeons started extensive fasciotomy of his arm, our anesthesia team gave several medications in tandem—calcium gluconate to stabilize cardiac myocytes and prevent ventricular arrythmia, coadministration of dextrose and insulin to induce an intracellular shift of potassium, sodium bicarbonate to induce cellular hydrogen/potassium exchange, and albuterol to increase cellular uptake of potassium via β2 adrenergic receptors (1,6). The patient’s hyperkalemia improved from 7.7 to 3.7 (normal 3.5 – 5.1mmol/L) over 4 hours. Discussion and Conclusion — Our review of available literature identified several methods of treatment of hyperkalemia, some with limitations to use which we believe support our team’s approach to treatment in this case report (6). Calcium salts are integral to the treatment of hyperkalemia by stabilizing cardiac myocytes, however they do not directly influence serum or total body potassium levels. Our report adds to a growing pool of existing case reports and small studies documenting safe, efficacious emergent treatment of hyperkalemia. It also describes the utility of the anesthesiologist in providing safe, effective perioperative medical care.

Diss. (sammanfattning) Umeå : Umeå universitet, 2010.

The tibialis anterior (TA) muscle plays a vital role in human movement such as walking and running. Overuse of TA during these movements leads to an increased susceptibility of injuries e.g. chronic exertional compartment syndrome. TA activation has been shown to be affected by increases in exercise, age, and the external environment (i.e. incline and footwear). Because activation parameters of TA change with condition, it leads to the interpretation that force changes occur too. However,activation is only an approximate indicator of force output of a muscle. Therefore, the overall aim of this thesis was to investigate the parameters affecting accurate measure of TA force, leading to development of a subject-specific EMG-driven model, which takes into consideration specific methodological issues. The first study investigated the reasons why the tendon excursion and geometric method differ so vastly in terms of estimation of TA moment arm. Tendon length changes during the tendon excursion method, and location of the TA line of action and irregularities between talus and foot rotations during the geometric method, were found to affect the accuracy of TA moment arm measurement. A novel, more valid, method was proposed. The second study investigated the errors associated with methods used to account for plantar flexor antagonist co-contraction. A new approach was presented and shown to be, at worse, equivalent to current methods, but allows for accounting throughout the complete range of motion. The final study utilised the outputs from studies one and two to directly measure TA force in vivo. This was used to develop, and validate, an EMG-driven TA force model. Less error was found in the accuracy of estimating TA force when the contractile component length changes were modelled using the ankle, as opposed to the muscle. Overall, these findings increase our understanding of not only the mechanics associated with TA and the ankle, but also improves our ability to accurately monitor these.

Compartment syndrome is a rare but a well-documented complication in patients with trauma-induced group A streptococcus infection. Here, we present a case of a male who developed compartment syndrome on the left lower extremity after an injury inoculated by group A streptococcus on the right lower extremity. The patient was resuscitated with antibiotics, urgent fasciotomy, and immunoglobulin. The patient was eventually transferred to a burn center for further care.

Introduktion: Omvårdnad är operationssjuksköterskans huvudområde. Operationssjuksköterskan ska förebygga skador och komplikationer som kan uppstå vid en operation. En sådan komplikation kan vara kompartmentsyndrom. Kompartmentsyndrom är en ovanlig komplikation men kan leda till allvarliga skador. Det är därför viktigt att operationssjuksköterskan beaktar det i sitt arbete. Syfte: Detta arbete syftar till att belysa operationssjuksköterskans erfarenheter av att arbeta med att förebygga kompartmentsyndrom i den perioperativa omvårdnaden. Metod: En kvalitativ ansats tillämpades och data samlades in via intervjuer. Insamlade data analyserades genom kvalitativ innehållsanalys. I arbetet deltog 11 operationssjuksköterskor, tio kvinnor och en man, som arbetade på fyra olika operationsavdelningar vid två olika sjukhus. Resultat: I den kvalitativa innehållsanalysen av texten framkom två kategorier, Att arbeta förebyggande samt Att handla på osäker grund. I den förstnämnda kategorin beskrevs hur operationssjuksköterskorna genomförde en individuell riskbedömning, var noggranna i positioneringen och utförde lägesändring samt massage av patientens ben för att förebygga kompartmentsyndrom. I den andra kategorin, Att handla på osäker grund, beskrevs en osäkerhet i den perioperativa omvårdnaden kring kompartmentsyndrom. Det belystes en osäkerhet runt ämnet, omvårdnadsinterventionerna ifrågasattes och en brist på vetenskaplig evidens framkom. Konklusion: Det fanns brister i riktlinjer och rutiner gällande omvårdnad kring kompartmentsyndrom. Det fanns även en brist i att implementera ny kunskap i operationssjuksköterskans omvårdnad för att kunna arbeta evidensbaserat. / Introduction: Nursing is the main area for the operating room (OR) nurse. The OR nurse will prevent injuries and complications that can occur during surgery. One such complication can be compartment syndrome. Compartment syndrome is a rare complication but can lead to serious injuries. It is therefore important that the OR nurse take this in consideration in their work. Aim: This essay aims to highlight the OR nurse's experiences of working with the prevention of compartment syndrome in the perioperative nursing. Method: A qualitative approach was applied and the data were collected through interviews. Collected data were analyzed by qualitative content analysis. The essay enrolled 11 OR nurses, ten women and one man, who worked in four different surgical wards at two different hospitals. Result: After a qualitative content analysis of the data were conducted two categories emerged, Preventive work and To act on uncertain foundations. The first category described how the OR nurse undertook an individual risk assessment, was accurate in positioning and performed a change in position and massage of the patient’s leg to prevent compartment syndrome. The second category, To act on uncertain foundations, described an uncertainty in the perioperative care regarding compartment syndrome. It highlighted an uncertainty around the topic, nursing interventions were questioned and a lack of scientific evidence emerged. Conclusion: There were a lack of guidelines and recommendations regarding care about compartment syndrome. There was also a lack of implementing new knowledge in nursing to provide an evidence-based practice.

Thesis (D.Phil.(Biokinetics, Sport and Leisure Sciences))--University of Pretoria, 2008. / Summary in English and Afrikaans. Includes bibliographical references.

Chronic exertional compartment syndrome (CECS) is a common problem within both military and athletic populations that can be difficult to diagnose. Furthermore, it is unclear what causes the development of CECS, particularly in the military population, as personnel undertake a variety of activities that can cause pain with CECS such as fast walking, marching and running. Chronic exertional compartment syndrome has been hypothesised to develop due to excessive muscle activity, foot pronation and abnormal biomechanics predominantly at the ankle. Treatment of CECS through running re-education to correct these abnormalities has been reported to improve symptoms. However no primary research has been carried out to investigate the biomechanical, muscle activation and clinical characteristics of military patients with CECS. The purpose of this thesis was to provide an original contribution to the knowledge through the exploration of these characteristics; and the development of insights into the development of CECS, with implications for prevention and treatment. Study one investigated the clinical characteristics of 93 service personnel with CECS. Plantar pressure variables, related to foot type and anterior compartment muscle activity, and ankle joint mobility were compared during walking between 70 cases and 70 controls in study two. Study three compared three-dimensional whole body kinematics, kinetics and lower limb muscle activity during walking and marching between 20 cases and 20 controls. Study four compared kinematics and lower limb muscle activity during running in a separate case-control cohort (n=40). Differences in electromyography (EMG) intensity during the gait cycle were compared in the frequency and time domain using wavelet analysis. All studies investigated subject anthropometry. Cases typically presented with bilateral, ‘tight’ or ‘burning’ pain in the anterior and lateral compartments of the lower leg that occurred within 10 minutes of exercise. This pain stopped all cases from exercising during marching and/or running. As such subsequent studies investigated the biomechanics of both ambulatory and running gaits. Cases in all case-control studies were 2-10 cm shorter; and were typically overweight resulting in a higher body mass index (BMI) than controls. There was strong evidence from study 3 that cases had greater relative stride lengths than controls during marching gait. This was achieved through an increase in ankle plantarflexion during late stance and a concomitant increase in the gastrocnemius medialis contraction intensity within the medium-high frequency wavelets. Given the differences in height observed, this may reflect ingrained alterations in gait resulting from military training; whereby all personnel are required to move at an even cadence and speed. These differences in stride length were also observed in walking and running gaits although to a lesser extent. There was no evidence from the EMG data that cases had greater tibialis anterior activation than controls during any activity tested, at any point in the gait cycle or in any frequency band. In agreement, there was also no evidence of differences between groups in plantar pressure derived measures of foot type, which modulate TA activity. Toe extensor - related plantar pressure variables also did not differ between groups. In summary, contrary to earlier theories, increased muscle activity of the anterior compartment musculature does not appear to be associated with CECS. The kinematic differences observed during running only partially matched the clinical observations previously described in the literature. Cases displayed less anterior trunk lean and less anterior pelvic tilt throughout the whole gait cycle and a more upright shank inclination angle during late swing (peak mean difference 3.5°, 4.1° and 7.3° respectively). However, no consistent differences were found at the ankle joint suggesting that running is unlikely to be the cause of CECS in the military; and that the reported success of biomechanical interventions may be due to reasons other than modifying pathological aspects of gait. In summary, the data presented in the thesis suggest that CECS is more likely to develop in subjects of shorter stature and that this is associated with marching at a constant speed and cadence. Biomechanical interventions for CECS, such as a change in foot strike or the use of foot orthotics, are unlikely to be efficacious for the military as personnel will continue to be required to march at prescribed speeds to satisfy occupational requirements. Preventative strategies that allow marching with a natural gait and/or at slower speeds may help reduce the incidence of CECS. The lack of association with foot type or muscle activity suggests that foot orthoses would not be a useful prevention strategy or treatment option for this condition.

Severe Acute Pancreatitis (SAP) is the rapid onset of inflammation within the pancreatic organ. Unlike the milder form of this illness, SAP is associated with a high mortality and morbidity. No significant reduction in the outcomes of this disease has been made since the implementation of organ supportive management over two decades ago. This is due to difficulties in distinguishing between the milder form of the disease in the early period of the onset of symptoms when clinical intervention is most likely to prevent complications and death. Clinical equipoise exists in the management of one of these complications, namely Abdominal Compartment Syndrome (ACS) as the conventional management of surgery runs contrary to published evidence showing early abdominal surgery deteriorates clinical outcomes. Aims: Validation of the potential use of the Early Warning Score (EWS) as a predictor of SAP. Evaluation of the evidence for recombinant human protein C (Xigris™) in the early treatment of SAP. Determination of the safety profile of Xigris™ when given early in SAP. To determine if surgical management of ACS in SAP is of significant benefit compared to conventional management alone. Methods: Four studies were performed: A prospective observational study assessing the median EWS of patients admitted with acute pancreatitis; a systematic review of published evidence reporting the use of Xigris™ in SAP; a prospective cohort study using a 24 hour infusion of Xigris™ early in patients diagnosed with SAP and a pilot randomized controlled trial of targeted decompression in patients with ACS complicating SAP. Results: The highest EWS values for 130 patients with acute pancreatitis within the first 3 days of admission were not shown to have significant sensitivity and specificity in predicting an unfavourable outcome. A review of the published literature between from January 1985 to January 2011 supported the further investigation of Xigris™ as a treatment for SAP. No significant adverse events or differences in outcomes were evident in 19 patients who received a 24-hour infusion of Xigris™ early in SAP compared to matched historical controls. 22 patients were screened for the development of ACS. No patient developed ACS and consequently no randomization to either treatment arm was possible. Conclusion: With the recent advent of an updated classification system for the severity of acute pancreatitis, further prospective evaluation of the use of EWS in clinical practice is warranted. The results of the Phase 1 clinical trial of Xigris™ didnot reveal significant safety issues that might preclude the further investigation of Xigris™ as a specific therapy early in the onset of SAP. The absence of ACS inpatients with SAP lends support to a theory that ACS may be an epiphenomenon in the course of SAP.