Measuring tissue perfusion during pressure relief maneuvers: insights into preventing pressure ulcers (original) (raw)
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Topics in Spinal Cord Injury Rehabilitation, 2011
Pressure ulcers (PUs) continue to be prevalent despite technologic advances in equipment development and repeated attempts to improve education and preventive efforts. Diligence and timeliness of adequate pressure relief are felt to be the cornerstone to PU prevention. The evidence supporting clinical recommendations for pressure relief is lacking, however, leading to inconsistencies in clinical guidelines. The purpose of this study is to contribute to the evidence base on PU pathophysiology and prevention in people with spinal cord injury (SCI) by delineating the microvascular mechanisms that occur during sitting and pressure relief maneuvers, including perfusion, oxygenation, and interface pressure. By understanding these key physiologic responses, health care professionals and consumers with SCI will be enabled to more effectively prevent the onset of PUs. The overriding goal of this project is to develop an algorithm that will assist clinicians in providing individualized recommendations specifying optimal pressure relief technique, duration, and frequency to reduce PU incidence in consumers with SCI.
SPIE Proc., 2013
Clinician’s recommendations on wheelchair pressure reliefs in the context of the high prevalence of pressure ulcers that occur in people with spinal cord injury is not supported by strong experimental evidence. Some data indicates that altered tissue perfusion and oxygenation occurring under pressure loads, such as during sitting, induce various pathophysiologic changes that may lead to pressure ulcers. Pressure causes a cascade of responses, including initial tissue hypoxia, which leads to ischemia, vascular leakage, tissue acidification, compensatory angiogenesis, thrombosis, and hyperemia, all of which may lead to tissue damage. We have developed an advanced skin sensor that allows measurement of oxygenation in addition to perfusion, and can be safely used during sitting. The sensor consists of a set of fiber optics probes, spectroscopic and Laser Doppler techniques that are used to obtain parameters of interest. The overriding goal of this project is to develop the evidence base for clinical recommendations on pressure reliefs. In this paper we will illustrate the experimental apparatus as well as some preliminary results of a small clinical trial conducted at the National Rehabilitation Hospital.
Dynamic changes in seating pressure gradient in wheelchair users with spinal cord injury
Assistive Technology, 2019
Pressure ulcer interventions are commonly assessed with measures of seating interface pressure, such as peak pressure gradients (PPGs). Decreases in PPG magnitudes may reduce pressure ulcer risk by decreasing tissue deformation and increasing tissue perfusion of at-risk weight-bearing tissues. Changes in PPG directions, which have previously been overlooked in the seating pressure literature, may provide a transient increase in blood flow to at-risk tissues, even if the PPG magnitude and location remain the same. The purpose of this study was to assess both PPG components in response to combinations of wheelchair tilt and recline angles. Thirteen power wheelchair users were recruited into the study. Six combinations of wheelchair tilt (15°, 25°, and 35°) and recline (10° and 30°) were tested in random order. Each combination was tested with 5min upright sitting, 5-min tilt and recline, and 5-min maximal pressure relief recovery. Changes in PPG magnitudes and PPG directions under the left ischial tuberosity were computed for the six angle combinations. The findings in this study suggested that when combining wheelchair tilt and recline, the recline function may be particularly useful in reducing PPG magnitudes, while the tilt function may be particularly useful in manipulating PPG directions.
Archives of Physical Medicine and Rehabilitation, 2010
Objective-To investigate the efficacy of wheelchair tilt-in-space and recline on enhancing skin perfusion over the ischial tuberosity in wheelchair users with spinal cord injury (SCI). Design-Repeated measures, intervention and outcomes measure design. Setting-A university research laboratory. Participants-11 wheelchair users with SCI (9 men, 2 women; mean age ± standard deviation, 37.7±14.2 years; body mass index 24.7±2.6 kg/m 2 ; and duration of injury 8.1±7.5 years). Interventions-6 protocols of various wheelchair tilt-in-space and recline angles were randomly assigned to the participants. Each protocol consisted of a 5-min sitting-induced ischemic period and a 5-min wheelchair tilt-in-space and recline pressure relieving period. A participant sat in a position without tilt or recline for 5 minutes and then sat in one of 6 wheelchair tiled and reclined positions, including (1) 15° tilt-in-space and 100° recline, (2) 25° tilt-in-space and 100° recline, (3) 35° tilt-in-space and 100° recline, (4) 15° tilt-in-space and 120° recline, (5) 25° tilt-in-space and 120° recline, and (6) 35° tilt-in-space and 120° recline. A 5-min washout period (at 35° tilt-inspace and 120° recline) was allowed between protocols. Main Outcome Measures-Laser Doppler flowmetry was used to measure skin perfusion over the ischial tuberosity in response to the changes of body positions caused by performing wheelchair tilt-in-space and recline. Skin perfusion response to wheelchair tilt-in-space and recline was normalized to skin perfusion of the upright seated position (no tilt/recline). Results-When combined with 100° recline, wheelchair tilt-in-space at 35° resulted in a significant increase in skin perfusion as compared with upright seated position (no tilt/recline)
Spinal Cord Injury and Pressure Ulcer Prevention: Using Functional Activity in Pressure Relief
Nursing Research and Practice, 2013
Background. People with spinal cord injury (SCI) are at increased risk of pressure ulcers due to prolonged periods of sitting. Concordance with pressure relieving movements is poor amongst this population, and one potential alternative to improve this would be to integrate pressure relieving movements into everyday functional activities.Objectives.To investigate both the current pressure relieving behaviours of SCI individuals during computer use and the application of an ergonomically adapted computer-based activity to reduce interface pressure.Design.Observational and repeated measures design.Setting.Regional Spinal Cord Injury Unit.Participants.Fourteen subjects diagnosed with SCI (12 male, 2 female).Intervention.Comparing normal sitting to seated movements and induced forward reaching positions.Main Outcome Measures.Interface pressure measurements: dispersion index (DI), peak pressure index (PPI), and total contact area (CA). The angle of trunk tilt was also measured.Results.The...
PLOS ONE
Pressure ulcers, by definition, are caused by external forces on the tissues, often in the regions of bony prominences. Wheelchair users are at risk to develop sitting-acquired pressure ulcers, which occur in the regions of the ischial tuberosities, sacrum/coccyx or greater trochanters. As a means to prevent pressure ulcers, instruction on performing pressure reliefs or weight shifts are a part of the rehabilitation process. The objective of this study was to monitor the weight shift activity of full-time wheelchair users with acute spinal cord injury over multiple epochs of time in order to determine consistency or routine within and across epochs. A second objective was to evaluate the accuracy of self-reported pressure relief frequency within each measurement epoch. A wheelchair in-seat activity monitor was used to measure weight shifts and other in-seat movement. The data was classified into multiple inseat activity metrics using machine learning. Seventeen full-time wheelchair users with spinal cord injury were measured within multiple epochs, each lasting more than 1 week. Across all in-seat activity metrics, no consistent pattern of activity changes emerged. None of the in-seat activity metric changed in any one direction across a majority of subjects. Subjects tended to overestimate their frequency of performing pressure reliefs. Self-reported pressure relief behaviors are not reliable, and therefore, cannot be used to evaluate preventative behaviors either clinically or within research. This study had the capability of fully investigating in-seat movements of wheelchair users. The results indicated that in-seat movement does not reflect a routine, either in pressure reliefs, weight shifts or other functional in-seat movements. This study has illustrated the complexity of assigning causation of pressure ulcer occurrence to seated behaviors of wheelchair users and identifies the need for improved clinical techniques designed to develop routine behaviors to prevent pressure ulcers.
Spinal Cord, 2011
This study was a repeated measures study. The objective was to systematically measure the relative reduction in interface pressure (IP) at the ischial tuberosities (IT) and sacrum through 10° increments of tilt in a manual wheelchair among individuals with motor complete spinal cord injury (SCI). This study was carried out in Manitoba, Canada. A total of 18 adults with ASIA A or B level of injury were recruited through an out-patient SCI clinic. Using a standardized protocol, participants were tilted in 10° increments between 0° and 50°, and IP readings were obtained at the IT and sacrum using pressure mapping technology. Relative pressure reduction from baseline was calculated and compared between tilt angles. Tilt angle had a highly significant effect on pressure reduction at the IT (P=0.000) and the cosine relationship between these variables was expressed as quadratic. Reduction in sacral pressure did not occur until 30° tilt, with increased loading at smaller tilt angles. Pressure reduction at the IT and sacrum was not significantly different for tetraplegic and paraplegic participants. Small tilt angles are more suitable for postural control than pressure management. A minimum tilt of 30° is required to initiate unloading the sacrum and to achieve a clinically important reduction in pressure at the IT. Larger tilt angles resulted in more substantial pressure reduction than previously reported. Tilt-in-space appears to have similar benefits for individuals with paraplegia and tetraplegia.
Pressure sore prevention for the wheelchair-bound spinal injury patient
Paraplegia
The concept of a wheelchair cushion fitting clinic for the prevention of pressure sores is reviewed in the light of recent estimates of the cost of pressure sores in the U.K. A method for measuring the pressure beneath the ischial tuberosities is discussed and techniques for measuring a patient's habitual exercise frequency and seated posture are described. Results from the records of 600 spinal injury patients including Rancho Los Amigos Hospital are reported and used to demonstrate the importance of low pressure beneath the ischial tuberosities as an indicator of wheelchair cushion suitability.
A comparative sudy of two pressure relieving techniques on three different wheelchair cushions
South African Journal of Physiotherapy
Introduction: Pressure relief done by a spinal cordinjured patient is of utmost importance in order to prevent pressuresore formation. Some pressure-relieving techniques are describedin previous literature, but their effectivity has not yet been deter-mined on different wheelchair cushions.Null Hypothesis (H0): The null hypothesis (H0) stated for thistudy is that there is no difference in the effectivity of forwardleaning and forward leaning towards the left as pressure relievingtechniques for quadriplegic wheelchair users over the differenwheelchair cushions.Design: An analytical experimental study design using a convenient sample group of ten complete lesion quadriplegics (C6 to T1) was performed at the Physiotherapy Department,University of Pretoria.Method: Interface pressure (in mmHg) over the ischial tuberosities and upper thigh areas was measured using theTalley Oxford Pressure Monitor MKII with a 12-way matrix cell system.Results and Conclusion: The Friedman test for associat...