Brief intermittent pressure off-loading on skin microclimate in healthy adults – A descriptive-correlational pilot study
Introduction
Pressure injuries (PIs) (also known as bedsores, pressure sores, or pressure ulcers) are injuries to the skin and the underlying soft tissue [1] caused by sustained mechanical loading and deformation of soft tissues between internal bony prominences and the external support surface [[2], [3], [4], [5]]. If the intensity and duration of deformation exceeds the capacity and resistance of the affected tissues, tissue ischemia will occur and necrotic regions may develop [6,7]. PIs are one of the most frequently-occurring yet potentially preventable adverse events in hospital [8]. On average, PI prevalence rates in hospitals range from 0.3% to 46% globally [9]. They are costly and challenging to heal, and result in poor patient outcomes [10]. In Australia, PIs are one of the top five most expensive adverse events [11], costing $1.8 billion per annum [12]. Epidemiological data indicate that PIs occur in all settings and age groups [6,13], however, they are a particularly common affliction in the bed-bound geriatric population [[14], [15], [16]]. In supine and semi-recumbent lying positions, the sacrum, elbows and heels are most susceptible to PI development [17,18] and are well known as PI predilection areas [2].
There are key risk factors that have been proposed in the conceptual schema of PI aetiology [19]. While interface pressure is generally considered to be the primary direct risk factor for PI development [[20], [21], [22], [23]], skin microclimate can be considered an indirect contributor [[24], [25], [26], [27]]. The concept of skin microclimate typically reflects the combination of temperature, moisture and/or humidity, and air movement at the skin support-surface interface [24] A review of the literature [[28], [29], [30], [31]] indicates that a suboptimal microclimate frequently precipitates early forms of PI onset. According to Gefen's mathematical model [32], altered microclimate conditions decrease cutaneous resistance which, in turn, leads to superficial skin changes at the affected area. Skin temperature, for instance, has been correlated with tissue injury in an animal study [33] and in a human study, it has been shown to increase by 1.2 °C in 24–96 h before PIs develop [34]. Specifically, a temperature increase in the microclimate causes a temperature increase of the stratum corneum and underlying cutaneous layers [35]. The water permeability of the stratum corneum is then raised [36], leading to an increase of transepidermal water loss [37,38] which aggravates possible moisture accumulation on the skin surface and in the stratum corneum. At the same time, the cohesive strength of the stratum corneum is reduced [39]. Studies [26,[40], [41], [42], [43], [44]] indicate that increased stratum corneum hydration results in changes in the mechanical properties of skin, influencing the resilience of the epidermal layer and thereby rendering the skin susceptible to damage due to shear and friction. The presence of prolonged moisture—in the form of perspiration, urine or wound exudate, for example—at the skin support-surface interface further weakens and softens the stratum corneum [26,43], making superficial damage through abrasion more likely (less friction is required to abrade the skin when it is damp) [43]. The establishment of an optimal microclimate of the skin is, therefore, a critical factor in deterring PI formation. Although suggestions about an optimal microclimate have been made [45,46], the exact range of an acceptable microclimate—including possible upper and lower thresholds— remains unknown.
Skin colour is determined, in part, by levels of haemoglobin; an oxygen-transporter contained within red blood cells [47], and melanin; a skin pigment produced by melanocytes [48]. The assessment of skin colour at pressure-prone areas can provide a direct reflection of several underlying physiological processes reflective of pressure-induced damage [49]. Specifically, erythema/skin redness signals imminent tissue damage. The presence of erythema is correlated with increased capillary and blood vessel dilation in the papillary and reticular dermis, and the subsequent increase in superficial plexus haemoglobin concentration. These protective mechanisms are designed to increase oxygenated blood delivery to the affected tissues [49,50]. If the pressure at the local tissue is not relieved, a domino effect is triggered, and extensive disruption to the local micro-circulation begins to occur. In this state, plasma has leaked from blood vessels into the interstitial tissues, and release of the iron pigment from haemoglobin leads to a persistent red staining of the skin [49].
In clinical practice, prevention of PI requires accurate assessment of skin status and monitoring of skin changes associated with PI development [2,51]. Skin moisture/wetness [52,53] and skin colour [49] are both critical and informative descriptors of skin status and, as such, are included as subscales in many standardised PI risk assessment scales [[53], [54], [55], [56], [57], [58]]. The assessment of these skin parameters, however, is heavily guided by the assessor's visual assessment and interpretation of skin status and—from a measurement perspective—may be unreliable. In general, empirical evidence supporting the validity of PI risk assessment scale scores is weak, with obtained scores containing varying amounts of measurement error [[59], [60], [61]]. For instance, the acquisition and communication of colour information visually is limited by descriptive language [62,63]. Although the human eye is capable of distinguishing between a vast range of similar colours [64], linguistic description is unable to satisfactorily convey distinct colour tones. Even though the clinician eye is capable of detecting the difference between skin colours, it cannot designate an absolute value for the detected colour difference. To illustrate, visual assessment is poor in precisely delineating the margins between distinct erythematous levels. Another point of critique regarding visual skin assessment is varying degrees of colour blindness which may exist undeclared among clinicians [65]. These limitations act as motivation for the application of biophysical techniques to assist accurate assessment of skin status. There are a range of non-invasive biophysical instruments—presently used within clinical dermatology for diagnostic and therapeutic purposes—which can numerically quantify stratum corneum hydration and skin colour [66]. The application of biophysical instruments in capturing these parameters in a PI context has the potential to enhance assessment accuracy by eliminating measurement subjectivity and, thus, addressing the aforementioned disadvantages of visual assessment.
A pilot study was undertaken to compare a series of skin parameter measurements taken during a period of sustained pressure-loading and intermittent pressure-relief of pressure-prone areas in healthy active adults lying supine and then semi-recumbent. To allow a comparison, repeated measures were taken across an uninterrupted method (immobilisation time 1 h) and an interrupted method (1 h of 10-min loading intervals, with a 20 s recovery in between). The objective of this study was to assess for skin parameter differences between methods (interrupted and uninterrupted) and timepoints (baseline and final) to capture their associations with skin parameters. This, in turn, would enable consideration if momentarily shifting pressure to enable measurements (a method being considered for other research initiatives) altered skin parameter readings.
Specifically, the following questions were raised:
- 1.
How do erythema, melanin, stratum corneum hydration, and skin temperature measures when assessed using biophysical techniques at the skin overlying bony prominences change over time?
- 2.
Is there agreement between uninterrupted and interrupted methods when assessing stratum corneum hydration, skin colour, and skin temperature over time? That is, are the results from skin parameter measurement altered or relatively unchanged during brief off-loading of bony prominences?
Section snippets
Ethics
This research was conducted in full concordance with the ethical principles of the 1975 Declaration of Helsinki, and within Australian laws and regulations for Higher Research (National Statement on Ethical Conduct in Human Research, 2018). Institutional review and approval for this study (Ref. #HEC20300) was received from the Human Research Ethics Committee of the affiliated university.
Design
A descriptive-correlational design pilot study was undertaken between February and July 2019.
Sample and recruitment
Convenience
Results
The sample (n = 41) comprised 28 females and 13 males with a mean age of 27.9 (SD = 10.6) years. Table 1 provides an overview of participant demographic data and clinical characteristics. A participant flow diagram illustrating participants’ involvement at baseline screening and inclusion in analyses is presented in Fig. 1
Discussion
A pilot study was undertaken to examine changes in skin microclimate and skin colour in response to continual pressure-loading (immobilisation time 1 h) and during intermittent pressure relief. A convenience sample of 41 healthy adults aged 18–60 years was recruited. The main objective of this research was to determine if intermittent off-loading at pressure-prone areas impacted skin parameter results. To enable a comparison of results following brief consecutive off-loading, repeated measures
Author contributions
CB, CM and BM designed the experiments. CB completed data collection. CB, CM and DV analysed the data. CB, CM, BM and DV interpreted the data. CB drafted the manuscript. All authors edited and approved the final version.
Ethics statement
This research was conducted in full concordance with the ethical principles of the 1975 Declaration of Helsinki, and within Australian laws and regulations for Higher Research (National Statement on Ethical Conduct in Human Research, 2018). Institutional review and approval for this study (Ref. #HEC20300) was received from the Human Research Ethics Committee of the affiliated university.
Disclosures
All other authors have no disclosures.
Declaration of competing interest
The authors have no financial or other sources of conflict of interest relating to the submission of this manuscript pertaining to the study: Brief intermittent pressure off-loading on skin microclimate in healthy adults – a descriptive-correlational pilot study.
References (95)
- et al.
Microclimate: a critical review in the context of pressure ulcer prevention
Clin Biomech
(2018) - et al.
Deformations, mechanical strains and stresses across the different hierarchical scales in weight-bearing soft tissues
J Tissue Viability
(2012) The epidemiology of skin conditions in the aged: a systematic review
J Tissue Viability
(2017)- et al.
Frequency of pressure ulcers in the paediatric population: a literature review and new empirical data
Int J Nurs Stud
(2010) - et al.
The epidemiology of skin conditions in the aged: a systematic review
J Tissue Viability
(2017) Does pressure cause pressure ulcers? An inquiry into the etiology of pressure ulcers
J Am Med Dir Assoc
(2010)How do microclimate factors affect the risk for superficial pressure ulcers: a mathematical modelling study
J Tissue Viability
(2011)- et al.
Elevated sacral skin temperature (T(s)): a risk factor for pressure ulcer development in hospitalized neurologically impaired Thai patients
Appl Nurs Res
(2005) - et al.
Mechanical properties of human stratum corneum: effects of temperature, hydration, and chemical treatment
Biomaterials
(2006) - et al.
Hydration disrupts human stratum corneum ultrastructure
J Invest Dermatol
(2003)