Doctor of Philosophy

dissertationHospital-acquired pressure injuries (PI) are localized areas of damage to the skin, underlying tissue, or both, as a result of pressure. Critical-care patients represent a highly specialized patient population, and currently available risk-assessment scales, such as the Braden scale, tend to identify most critical-care patients as being "at risk" for pressure injuries, and therefore are of limited clinical utility. The purpose of this dissertation was to (a) conduct a systematic review of the literature to identify independent risk factors for pressure injuries, (b) use longitudinal analysis to identify the hazards of developing a pressure injury based on changing Braden Scale total and subscale scores, and (c) develop a PI prediction model. We conducted our systematic review based on standardized criteria and developed a tool for quality assessment based on a literature search and input from experts. Mobility/activity, age, and vasopressor infusion emerged as important risk factors, whereas results from other risk categories were mixed. For the Braden scale analysis and the predictive model we used electronic health record cases (N=6,376). We employed time-dependent Cox regression to determine the hazards of developing a pressure injuries based on the Braden scale subscale scores. With the exception of the friction and shear subscales, patients of all ages with midrange Braden scale scores were more likely to develop pressure injuries than their counterparts with higher risk scores. We developed a predictive model using random forest analysis. The model, an ensemble classifier, was composed of 500 decision trees, each using a random subset of 4 of 20 clinical features. The area under the receiver operating characteristic curve was 0.9 for the outcome >category 1 pressure injuries and 0.87 for the outcome >category 2 pressure injuries. The most important variables in our model in descending order based on the mean decrease in accuracy were longer surgical duration, lower hemoglobin, higher creatinine, older age, higher glucose, lower body mass index, lower albumin, and higher lactate. Due to our model's relatively strong performance, it may be useful for directing preventive interventions that are not feasible for every patient due to cost

Predictive validity of the INTEGRARE scale in identifying the risk of hospital-acquired pressure ulcers in acute care hospital settings

Background: Hospital-acquired pressure ulcers (HAPUs) are prevalent around the world and are an indicator of care quality. Numerous instruments are available to predict their appearance, but few evaluate predictive val idity. No instruments based on Nursing Outcomes Classification indicators have been found, despite these in dicators reflecting the patient’s condition. The aim of the study was to analyse the predictive validity of the INTEGRARE scale in preventing the risk of HAPUs. Methods: A multicentre prospective observational cohort study design was used. 1,004 patients from 11 public hospitals in Andalusia (Spain) were recruited between February 2015 and October 2017. Participants were aged over 18 and had been admitted to medical and surgical units, with a predicted stay exceeding 48 h. Predictive validity was checked using a multivariate logistic regression model and a receiver operating characteristic curve, with development of pressure ulcers during the hospital stay as the dependent variable. Results: The INTEGRARE scale obtained an area under the curve of 0.886 (95% CI = 0.85–0.923). Within the 30- point range, the optimal cut-off value is 23 points with a sensitivity of 80.8% and a specificity of 80%. The odds ratio was 16.86 (95% CI = 8.54–33.28). Among the patient variables, age was significant, while among the hospital variables, the type of unit and the Nurse Staffing Level (NSL) were significant. Conclusions: The INTEGRARE scale has robust predictive validity when patients are admitted to medical and surgical inpatient units. Patients with a higher risk of developing HAPUs are in surgical units, are elderly, and have an NSL exceeding 10.4

A three constituent mixture theory model of cutaneous and subcutaneous tissue in the context of neonatal pressure ulcer etiology and prevention

Localized ischemia, impaired interstitial fluid flow, and sustained mechanical loading of cells have all been hypothesized as mechanisms of pressure ulcer (PrU) etiology. Time-varying loading has experimentally been shown to increase fluid flow in human skin in vivo. Towards the design of prophylactic protocols and treatment modalities for PrU management there is a need for an analytical model to investigate the local fluid flow characteristics of skin tissue under time-varying loading. In this study, a triphasic mixture theory model with constituents of extracellular matrix, interstitial fluid, and blood was calibrated and validated and used to investigate stress and fluid velocity under quasi-static and time-varying loading conditions, respectively. Four input strain profiles were considered, including uniform, geometric circular segment, Gaussian, and Hertz-type strain profiles. Calibrated bulk and shear modulus (κ;=227.7kPa, µ=1.04kPa) were on the same order of magnitude as literature. Fluid velocities were investigated for apparent strain amplitudes of 100-700μϵ and frequencies of 10-80Hz. At the lowest amplitude and frequency, interstitial fluid velocities were on the same order of magnitude as literature values, 1 micrometers/s and 1 mm/s, respectively. Interstitial fluid and blood velocity both experienced significant increases with increasing amplitude and frequency. The study demonstrated the ability to analytically predict quasi-static stress profiles as well as predict fluid velocity increases in cyclically loaded soft tissues by employing quasi-static mechanics and mixture theory models. Consequently, this study builds a strong foundation for use in the development of vibrational support surfaces for use in prophylactic protocols and adjunctive treatment modalities for PrU managemen

The pressure injury predictive model: A framework for hospital‐acquired pressure injuries

BackgroundDespite decades of research, pressure injuries continue to be a source of significant pain and delayed recovery for patients and substantial quality and cost issues for hospitals. Consideration of the current thinking around pressure injury risk must be evaluated to improve risk assessments and subsequent nursing interventions aimed at reducing hospital‐acquired pressure injuries.DesignThis is a discursive paper using Walker and Avant’s (2005) theory synthesis framework to examine the relevance of existing pressure injury models as they align with the current literature.MethodsPubMed and CINAHL indexes were searched, first for conceptual models and then for pressure injury research conducted on hospitalised patients for the years 2006–2016. A synthesis of the searches culminated into a new pressure injury risk model.ConclusionsGaps in previous models include lack of attention to the environment, contributing episode‐of‐care factors and the dynamic nature of injury risk for patients. Through theory synthesis, the need for a new model representing the full risk for pressure injury was identified. The Pressure Injury Predictive Model is a representation of the complex and dynamic nature of pressure injury risk that builds on previous models and addresses new patient, contextual and episode‐of‐care process influences. The Pressure Injury Predictive Model (PIPM) provides a more accurate picture of the complexity of contextual and process factors associated with pressure injury development.Relevance to Clinical PracticeUsing the PIPM to determine risk can result in improved risk identification. This information can be used to implement targeted, evidence‐based pressure injury prevention interventions specific to the patient risk profile, thus limiting unwarranted and unnecessary care.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154245/1/jocn15171.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154245/2/jocn15171_am.pd

Doctor of Philosophy

dissertationHospitals acquired pressure ulcers (HAPUs), a nationally recognized indicator of hospital and nursing quality, pose a notable risk to hospitalized patients for pain, debility and death. Oncology patients represent a large portion of hospitalized patients. Numerous common cancer symptoms and complications are known risk factors for HAPUs. HAPU prevalence in oncology units is unknown. Previous research has demonstrated that nurse education and practice environments are significantly related to patient outcomes. The relationship between these variables and HAPUs is unknown. The purpose of this research was to examine the risk for and prevalence of HAPUs on oncology units and evaluate the relationship between them and nursing variables by comparing oncology units to nononcology units. The sample included 145 oncology and 212 nononcology units. Mean unit HAPU prevalence rates for all stage ulcers was not significantly different between unit types (2.9% and 2.6%; p > .05). Total ulcer rates likewise failed to demonstrate significance (10.9% and 11.2%; p > .05). Unit mean Braden Scale scores measuring risk for HAPU on admission were different with the oncology unit mean significantly higher, demonstrating less patient risk for breakdown, than nononcology units (19.0 and 18.6; p > .05). This difference was lost over time, as the unit mean for nononcology units improved between admission and the last recorded to score to 18.9, while the oncology unit mean remained stable at 19.0. No difference was found in mean percent of nurses with a BSN by unit (55.3% and 54.1%). Nurse practice environment, measured with the Practice Environment Scale of the Nurse Work Index (PES-NWI), failed to demonstrated significant differences on any of the five subscales or the total score (p > .05) between unit types. A moderated mediation analysis, utilized to evaluate the relationship of the nurse variables to HAPUs, failed to reach significance on either unit type. The lack of difference by unit type for risk, prevalence, and nursing variables reduces the need to examine oncology units individually from other units. Continued efforts to understand the development of HAPUs needs to incorporate changing rates over time and evolve the relationship to nurse variables

A HYBRID METHODOLOGY FOR MODELING RISK OF ADVERSE EVENTS IN COMPLEX HEALTHCARE SETTINGS

Despite efforts to provide safe, effective medical care, adverse events still occur with some regularity. While risk cannot be entirely eliminated from healthcare activities, an important goal is to develop effective and durable mitigation strategies to render the system `safer'. In order to do this, though, we must develop models that comprehensively and realistically characterize the risk. In the healthcare domain, this can be extremely challenging due to the wide variability in the way that healthcare processes and interventions are executed and also due to the dynamic nature of risk in this particular domain. In this study we have developed a generic methodology for evaluating dynamic changes in adverse event risk in acute care hospitals as a function of organizational and non-organizational factors, using a combination of modeling formalisms. First, a system dynamics (SD) framework is used to demonstrate how organizational level and policy level contributions to risk evolve over time, and how policies and decisions may affect the general system-level contribution to adverse event risk. It also captures the feedback of organizational factors and decisions over time and the non-linearities in these feedback effects. Second, Bayesian Belief Network (BBN) framework is used to represent patient-level factors and also physician level decisions and factors in the management of an individual patient, which contribute to the risk of hospital-acquired adverse event. The model is intended to support hospital decisions with regards to staffing, length of stay, and investment in safeties, which evolve dynamically over time. The methodology has been applied in modeling the two types of common adverse events; pressure ulcers and vascular catheter-associated infection, and has been validated with eight years of clinical data

PRESSURE ULCERS AND PREVENTION AMONG PEDIATRIC PATIENTS AND FACTORS ASSOCIATED WITH THEIR OOCCURENCE IN ACUTE CARE HOSPITALS

Abstract Introduction: Pressure ulcers are a health-care concern for all patient populations; however, younger patients, including infants, have different etiologies associated with pressure ulcer development. The influence of hospital, unit, and nursing factors on hospital-acquired pressure ulcers (HAPU) rates have not been evaluated in pediatric patients. Comparative data for pediatric patients is necessary for hospitals to improve the care related to prevention and treatment of pediatric pressure ulcers. Purpose: The purpose of this study was to describe (a) the pressure ulcer prevalence rate and the rate of HAPU in pediatric patients; (b) the frequency of patient pressure ulcer risk assessment and prevention interventions; and (c) patient pressure ulcer risk and prevention interventions, microsystem factors, and mesosystem factors associated with HAPU among pediatric patients in U.S. hospitals. Method: A descriptive correlational secondary analysis was performed on National Database for Nursing Quality Indicators® (NDNQI®) pressure ulcer data for 2012. Results: This study found a pressure ulcer prevalence of 1.4% and a 1.1% rate of HAPU among pediatric patients 1 day to 18 years of age. HAPU rates were highest among children ages 9 to18 years (1.6%) and ages 5 to 8 years (1.4%) and among patients in the pediatric critical care units (3.7%) and pediatric rehabilitation units (4.6%). Most of the HAPU were Stage I and Stage II pressure ulcers (65.6%); 14.3% were suspected Deep Tissue Injury and 10.1% were unstageable pressure ulcers. The odds for a HAPU were 9.42 times higher among patients who were determined to be at risk for pressure ulcers (OR = 9.42, 95% CI [7.28, 12.17], p <.001) compared to those patients not at risk for pressure ulcers. Patients from pediatric hospitals had 2.67 higher odds for a HAPU compared to patients from nonpediatric hospitals (OR = 2.67, 95% CI [1.5, 4.76, p = .001). Among the 11,203 pediatric patients at risk for pressure ulcers, 95.8% received one or more prevention interventions. There were no prevention interventions associated with lower HAPU. Conclusions: Acutely ill children develop pressure ulcers. Study findings provide baseline data on HAPU among hospitalized children and microsystem and mesosystem factors associated with their HAPU

Automatic Segmentation of Pressure Images Acquired in a Clinical Setting

One of the major obstacles to pressure ulcer research is the difficulty in accurately measuring mechanical loading of specific anatomical sites. A human motion analysis system capable of automatically segmenting a patient\u27s body into high-risk areas can greatly improve the ability of researchers and clinicians to understand how pressure ulcers develop in a hospital environment. This project has developed automated computational methods and algorithms to analyze pressure images acquired in a hospital setting. The algorithm achieved 99% overall accuracy for the classification of pressure images into three pose classes (left lateral, supine, and right lateral). An applied kinematic model estimated the overall pose of the patient. The algorithm accuracy depended on the body site, with the sacrum, left trochanter, and right trochanter achieving an accuracy of 87-93%. This project reliably segments pressure images into high-risk regions of interest

Risk Factors for Pressure Injuries Among Critical Care Patients: A Systematic Review

Objective: To identify risk factors independently predictive of pressure injury (also known as pressure ulcer) development among critical-care patients. Design: We undertook a systematic review of primary research based on standardized criteria set forth by the Institute of Medicine. Data sources: We searched the following databases: CINAHL (EBSCOhost), the Cochrane Library (Wilson), Dissertations & Theses Global (ProQuest), PubMed (National Library of Medicine), and Scopus. There was no language restriction. Method: A research librarian coordinated the search strategy. Articles that potentially met inclusion criteria were screened by two investigators. Among the articles that met selection criteria, one investigator extracted data and a second investigator reviewed the data for accuracy. Based on a literature search, we developed a tool for assessing study quality using a combination of currently available tools and expert input. We used the method developed by Coleman et al. in 2014 to generate evidence tables and a summary narrative synthesis by domain and subdomain. Results: Of 1753 abstracts reviewed, 158 were identified as potentially eligible and 18 fulfilled eligibility criteria. Five studies were classified as high quality, two were moderate quality, nine were low quality, and two were of very low quality. Age, mobility/activity, perfusion, and vasopressor infusion emerged as important risk factors for pressure injury development, whereas results for risk categories that are theoretically important, including nutrition, and skin/pressure injury status, were mixed. Methodological limitations across studies limited the generalizability of the results, and future research is needed, particularly to evaluate risk conferred by altered nutrition and skin/pressure injury status, and to further elucidate the effects of perfusion-related variables. Conclusions: Results underscore the importance of avoiding overinterpretation of a single study, and the importance of taking study quality into consideration when reviewing risk factors. Maximal pressure injury prevention efforts are particularly important among critical-care patients who are older, have altered mobility, experience poor perfusion, or who are receiving a vasopressor infusion

Exploring preventive interventions and risk factors of hospital-acquired pressure ulcers: A retrospective matched case-control design.

Previous literature showed weak and sometimes contradictory evidence regarding the best interventions to prevent pressure ulcers and the best factors that can serve as predictors for ulceration. The aim of this study was to explore effective interventions and associated risk factors in the area of pressure ulcer. A retrospective approach was used to explore such interventions and risk factors in a more natural clinical environment than found in a prospective study. While retrospective studies have their limitations, one problem of prospective studies, the Hawthorn effect, is not present. In order to meet the aims of the study, a matched case-controlled design was employed. A convenience sampling technique was used to select all patients who matched the study criteria. Two groups of patients were selected. The first group developed pressure ulcer during hospitalization, the other did not. In order to have a sound and robust comparison, each patient from the pressure ulcer groups was matched or at least nearly matched with another patient from the non-pressure ulcer group for a number Waterlow sub-scores. Further criteria for selection included a minimum of three days total length of stay in hospital and being initially free of any pressure ulcer on admission for both of the study groups. Electronic medical records for all patients were revised, and multidimensional data were extracted using a data extraction sheet. Data analyses were carried out using univariate analysis (t-test, Mann-Whitney, Chi-square and Fisher’s exact test) and multivariate analysis (binary logistic regression). In univariate analysis for preventive interventions, the following interventions were significantly associated with pressure ulcer prevention (P≤ 0.05): standard hospital bed, seating cushion, static pressure redistributing mattress, re-positioning every four hours and helping the patient to sit regularly in a chair. When the effect of all interventions was adjusted through the multivariate model, the following interventions were independently associated with prevention: draw sheet, re-positioning every four hours and helping patient to sit regularly in chair (odds ratio = 0.24, 0.06 and 0.13 respectively; P≤ 0.05). In univariate analysis for risk factors related to physical activity and mobility, the following factors were significantly associated with developing pressure ulcer (P≤ 0.05): moving in bed with help, the ability to take a bath only in bed, needing two helpers in performing activities of daily living and moving outside bed only by a hoist. When adjusting the effect of all variables related to physical activity and mobility through the multivariate model, only two factors were independently associated with developing pressure ulcer: moving in bed with help and the ability to take a bath only in bed (odds ratio = 7.69 and 3.67 respectively; P≤ 0.05). In univariate analysis for risk factors related to pressure ulcer intrinsic risk factors, the following factors were significantly associated with developing pressure ulcer (P≤ 0.05): presence of three underlying medical conditions, dehydration, depression, having a blood transfusion, serum albumin <32mg/dl, haemoglobin <130 g/l in males or <115 for females and systolic blood pressure <113 mmHg. When adjusting the effect of all variables related to intrinsic risk factors through the multivariate model, the following risk factors were independently associated with pressure ulcer: presence of two underlying medical conditions, presence of three underlying medical conditions, cognitive impairment, serum albumin <32mg/dl and haemoglobin <130 g/l in males or <115 for females (odds ratio = 13.3, 143, 4.3, 0.10 and 0.14 respectively; P≤ 0.05). Findings from this study suggest a number of interventions to be effective in PUs prevention, and a number of risk factors that can predict risk of PUs. Findings were based on statistical association between acquiring PUs and the independent variables (preventive interventions and risk factors). This cannot constitute a cause and effect relationship due to the retrospective nature of data analyzed; it only supports the association between a number of interventions and risk factors in preventing or predicting PUs. This can guide further research to investigate these interventions and risk factors by employing the same approach used, but in a prospective manner