The main issues from the baseline study were twofold. First, there were interface pressure (IP) risks on the X-ray table without mattress (hard surface) which could cause tissue damage and lead to Medical Device Related (MDR) pressure ulcers among patients undergoing prolonged radiography, radiotherapy planning and treatment procedures. Second, the specific health characteristics of patients who are likely to access these prolonged procedures makes the interface pressure risks more likely to predispose them to the formation of pressure ulcers. The baseline research in this thesis has demonstrated that mean IP for the whole body on the X-ray table with no mattress exceeds the threshold (32 mmHg) above which IP may induce occlusion of capillary blood flow, which may cause reduced tissue perfusion, ischemic injury, and therefore increase the risk of pressure ulcer development (Dharmarajan and Ugalino, 2002, Thomas, 1997). However, using mean IP for the whole body as a parameter to predict patient risk of developing pressure ulcers would be of little if any clinical significance. This is because mean IP for the whole body does not give a clear indication of the IP distribution across the entire skin surface of a patient’s body. That is, it fails to give a clear indication of the pressure brought to bear on specific anatomical areas.
To illustrate this point, consider volunteers three and fifteen who participated in the baseline study in this thesis. These volunteers, both males, had similar ages (26 and 28 years respectively); body mass indexes (25.4 and 23.2, respectively); and approximately the same mean IP for the whole body on the X-ray table without mattress (42.7 and 42.3 mmHg, respectively). However, when the pressure mapping data of volunteer three was analysed, the results showed large differences in the IP distribution across the jeopardy areas; mean IP for the head, sacrum, right and left heels were 138.0±2.5, 50.8±1.8, 43.2±2.1 and 24.9±1.2 mmHg, respectively. Compared to the IP distribution for the head, sacrum and heels of volunteer fifteen, the results showed a fairly homogenous IP distribution across the jeopardy areas ((head (53.6±1.3), sacrum (56.8±2.6), right heel (30.1±4.2) and left heel (21.0±2.1) mmHg). Therefore to conclude that volunteers three and fifteen have the same risk of developing pressure ulcers because they experienced the same mean IP for the whole body will not be accurate. This is because as demonstrated, the IP brought to
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bear on the jeopardy areas were different. The implication of the differences in IP distribution in these two volunteers is that, all other factors being equal, the risk of volunteer three developing a pressure ulcer at the head is significantly higher than that of volunteer fifteen. Using the mean IP for the whole body as a parameter to assess the risk of developing pressure ulcers would result in an over-prediction, or an under-prediction of pressure ulcer risk. This could lead to waste of hospital resources, because patients who may not be at risk of developing pressure ulcers may be placed on pressure ulcers preventive programmes, and those who are at risk may not be picked up to be placed on preventive measures.
The results of the baseline study in this thesis had demonstrated that mattress surface overlays help to redistribute interface pressure, thereby helping to reduce volunteers’ risk of developing Medical Device Related (MDR) pressure ulcers. This could have a significant clinical implication for radiography practice in Ghana and Portugal because they do not use mattresses on X-ray tables. If the findings of this thesis are applied into conventional radiography practice in these countries, practice could change for the better, in the sense that patients will be provided with mattresses. This will enhance patient care and improve patient management because the introduction of a mattress will reduce IP, thereby reducing the risk of developing MDR pressure ulcers from medical imaging and radiotherapy planning and treatment surfaces.
Although high interface pressure risks have been identified for the head on the X-ray table with no mattress (hard surface), it is unlikely to induce tissue ischaemia, which would lead to pressure ulcers in patients undergoing conventional radiography procedures. This is because most conventional imaging procedures take a very short time to complete, mostly less than ten minutes (Ball et al., 2008, Whitley et al., 2005). Additionally, most conventional radiography procedures require at least two projections, usually anterioposterior (AP) and lateral projections (Whitley et al., 2005). As different patient positions are required during imaging protocols the patient often has to move, thereby relieving pressure on jeopardy areas. This means that IP between the anatomical part being x-rayed and the imaging surface will not be sustained long enough to induce tissue ischaemia. Consequently, patient movement between projections will reduce the risk of developing pressure ulcers (Dharmarajan and Ugalino, 2002). Also, during conventional radiotherapy procedures, patients are
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provided with pillows when the head is not in the radiation field. This will provide some level of cushioning to the head, which will lower the IP between the head and the X-ray table thereby reducing the risk of developing pressure ulcers.
However, high interface pressure risk on X-ray tables with no mattress could induce tissue ischaemia which may lead to developing pressure ulcers in patients undergoing lengthy imaging procedures, for example interventional radiography procedures. This is because these procedures take a long time to complete, some taking several hours. In countries that do not use mattresses for imaging procedures, patients undergoing prolonged intervention radiography procedures such as cervical vertebroplasty would be required to lie on a hard imaging surface without any form of cushioning for long periods of time. Cervical vertebroplasty is a percutaneous minimally invasive interventional radiography procedure used to treat painful cervical vertebral compression fractures (VCFs) (Zhao et al., 2016a, Yang et al., 2016). Cervical VCFs can be defined as fractures involving the vertebral bodies of the cervical spine, and are common among patients of advancing age (Yan et al., 2016). Cervical vertebroplasty takes over an hour to complete, and sometimes longer if several cervical fractures are present (Wong and McGirt, 2013).
The treatment goals of cervical vertebroplasty are to relieve pain, restore mobility, restore vertebral body height, avoid new fractures, improve physical function, and enhance patient’s quality of life (Alexandru and So, 2012). The presence of cervical vertebral fractures can cause a radical change in the rectangular shape of the affected cervical vertebra, causing it to compress against each other and/or surrounding tissues and nerves (Noriega et al., 2016). This results in most patients experiencing long-lasting, high pain intensity, and disabling condition resulting in impaired physical function and reduced quality of life (Svensson et al., 2016, Suzuki et al., 2008). Osteoporosis, a systemic bone disease that results in a loss of normal bone density, mass, strength, and a degradation of vertebral skeletal microarchitecture, leading to a condition in which bones are increasingly weak, and porous, making them susceptible to fracturing easily, is the common cause of cervical VCF (Zhao et al., 2016a). However, primary and metastatic malignancies, trauma, hemangioma, and osteonecrosis are other aetiologies of cervical vertebrae fractures (Jay and Ahn, 2013).
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Most patients suffering from cervical VCF can be successfully managed with traditional treatments, including bed rest, analgesics, brace, and physical therapy (Sebaaly et al., 2016). However, older age is one of the risk factors for traditional treatments failure (Lee et al., 2012), and in some instances, these traditional treatments are associated with higher rates of pneumonia, venous thromboembolism, and even death in patients of advancing age (Yang et al., 2016). Cervical vertebroplasty has therefore become widely accepted as a treatment for cervical VCF especially among older patients (Yang et al., 2016).
During cervical vertebroplasty, fluoroscopic X-ray machines are used to provide image-guidance whilst orthopedic barium-opacified polymethylmethacrylate (PMMA) cement is injected into the fractured vertebrae (Nakamae et al., 2015). The orthopedic cement can easily been seen on the fluoroscopic image, and hardens soon after injection into the vertebrae (Saracen and Kotwica, 2014). The injected orthopaedic cement stabilises pathological micro fractures and reduces mechanical forces that affect nervous structures and causes pain (De la Garza-Ramos et al., 2016, Burton et al., 2005). Considering the fact that fluoroscopic X-ray machines in Ghana do not use mattresses, patients undergoing cervical vertebroplasty would be required to lie on hard rigid fluoroscopic X-ray surfaces throughout the duration of the procedure. It must be stated that patients’ head are not supported on pillows during cervical vertebroplasty due to the possibility that the pillow might elevate the head above the level of the cervical spine, thereby putting pressure on the already distressed cervical spine. This might increase the pain in the cervical spine, and also increase cement leaks within the vertebrae (De la Garza-Ramos et al., 2016). Additionally, the proximity of the cervical vertebrae to the head demands that the head is not supported on pillows because the use of pillows could produce artefacts, which might affect the diagnostic quality of the fluoroscopic image. It is a common practice in radiography that any anatomical area to be irradiated and its immediate surrounding are kept free of foreign materials (Whitley et al., 2005). The absence of pillow or any form of cushioning at the head could induce tissue damage at the head because the head will be in direct contact with the rigid fluoroscopic surface for prolonged period of time.
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