Margareta Lindgren

Blood flow measurements at different depths using photoplethysmography and laser Doppler techniques

Background/purpose: This study has evaluated a multi‐parametric system combining laser Doppler flowmetry and photoplethysmography in a single probe for the simultaneous measurement of blood flow at different depths in the tissue. This system will be used to facilitate the understanding of pressure ulcer formation and in the evaluation of pressure ulcer mattresses.

Predictive validity of 4 risk assessment scales for prediction of pressure ulcer development in a hospital setting

OBJECTIVES: The aims of this study were to examine and compare the predictive validity of 4 risk assessment scales used for the prediction of pressure ulcer (PrU) development and to identify risk factors. DESIGN: Cross-sectional descriptive study. SETTING: A general hospital in Sweden. PARTICIPANTS: Patients (all aged ≥18 years) admitted to medical, surgical, orthopedic, oncology, and rehabilitation wards. Of 412 patients available, a total of 346 patients participated in the study. METHOD: Data were collected using the Swedish version of the European Pressure Ulcer Advisory Panel minimum data set as well as the Norton, Modified Norton, Braden, and Risk Assessment Pressure Sore (Ulcer) (RAPS) scales. The predictive validity was estimated by measuring sensitivity, specificity, positive predictive value, and negative predictive value. Multiple logistic regression analysis was used to determine risk factors associated with PrUs. RESULTS: The RAPS scale reached best balance between sensitivity and specificity at the recommended cutoff level of ⩽29, followed by the Braden scale and the Norton scale at recommended cutoff levels ⩽18 versus ⩽16, respectively. The modified Norton scale also reached an acceptable balance between sensitivity and specificity but at the cutoff level of ⩽23, which is a higher cutoff level than recommended. General physical condition, physical activity, moisture, friction, and shear emerged as significant risk factors. CONCLUSIONS: The results support that the recommended cutoff levels of the RAPS, Norton, and Braden scales are valid in a general hospital setting. However, the recommended cutoff level of the modified Norton scale (⩽20) has to be increased when used in this care context.

Dressing the split-thickness skin graft donor site: a randomized clinical trial

OBJECTIVE:The primary objective of this study was to compare Aquacel (ConvaTec, Skillman, New Jersey), Allevyn (Smith & Nephew, St Petersburg, Florida), and Mediskin I (Mölnlycke, Health Care AB, Gothenburg, Sweden) in the treatment of split-thickness skin graft donor sites. DESIGN:This study was performed as a prospective randomized, 3-arm, clinical study. SETTING:A clinical study performed at a hand and plastic surgery department with burn unit. PARTICIPANTS:The study included 67 adults with a total of 73 donor sites, which were on the thigh, not reharvested, and ranged between 30- and 400-cm2 area. INTERVENTIONS:Subjects were randomly assigned to treatment with Aquacel, Allevyn, or Mediskin I. MAIN OUTCOME MEASURES:The donor site was assessed on postoperative days 3, 14, and 21 for healing, infection, pain, impact on everyday life, ease of use, and cost. MAIN RESULTS:The obtained results demonstrate significantly faster re-epithelialization for patients treated with Aquacel or Mediskin I compared with Allevyn. Regarding infections, there were no significant differences between the groups. Patients wearing Aquacel experienced significantly less pain changing the dressing and less impact on everyday life than the patients wearing Allevyn. Aquacel was shown to be significantly easier for the caregiver to use than Allevyn and Mediskin I. There is a significant difference in cost of treatment between the dressings, whereas Mediskin I is the most expensive. CONCLUSION:The authors’ results support the use of Aquacel in the treatment of split-thickness skin graft donor sites. Aquacel has a low cost per unit, is user friendly, gives short healing time, and minimizes patient discomfort.

Existence of Tissue Blood Flow in Response to External Pressure in the Sacral Region of Elderly Individuals - Using an Optical Probe Prototype

Microcirculation (2010) 17, 311–319. doi: 10.1111/j.1549‐8719.2010.00027.x

Altered skin blood perfusion in areas with non blanchable erythema: an explorative study

Non blanchable erythema, i.e. stage I pressure ulcer, is common in patients in acute and geriatric care and in nursing homes. Research has shown that this type of lesions is prone to develop into more severe pressure ulcers. The peripheral skin blood perfusion is of major importance for the development of pressure ulcers. The aim of this study was to explore the peripheral skin blood perfusion over time, in areas with non blanchable erythema and in corresponding undamaged areas on the opposite side of the body. A total of 19 measurements were performed, over time, using a laser Doppler perfusion imager. The blood flow distribution profiles over areas with non blanchable erythema and undamaged skin were found to be different. As the area of the non blanchable erythema decreased, the blood perfusion distribution profiles gradually became more heterogeneous; an area of high blood perfusion in the centre of the lesions was seen and the perfusion successively decreased closer to the edge. These results indicate that there are differences in blood perfusion between skin areas of non blanchable erythema and undamaged skin. The results also indicate that the visible redness in areas with non blanchable erythema is related to altered blood perfusion. The skin blood perfusion also seems to increase in relation to the size of the non blanchable erythema.

Different lying positions and their effects on tissue blood flow and skin temperature in older adult patients

AIM To report a study to compare the effects of different lying positions on tissue blood flow and skin temperature in older adult patients. This article reports the evaluation of study design and procedures. BACKGROUND To reduce risk of pressure ulcers, repositioning of immobile patients is a standard nursing practice; however, research into how different lying positions effect tissue microcirculation is limited. DESIGN Descriptive comparative design. METHODS From March-October 2010, 20 inpatients, aged 65 years or older, were included in the study. Tissue blood flow and skin temperature were measured over bony prominences and in gluteus muscle in four supine and two lateral positions. RESULTS The blood flow over the bony prominence areas was most influenced in the superficial skin and especially in the 30° lateral position, where the blood flow decreased significantly in comparison with the supine positions. There were significant individual differences in blood flow responses, but no common trend was identified among the patients considered at risk for pressure ulcer development. The study procedure worked well and was feasible to perform in an inpatient population. CONCLUSION The lying positions seem to influence the tissue blood flow over the bony prominences in different ways in older adult inpatients, but further study is needed to confirm the results and to make recommendations to clinical practice. The study procedure worked well, although some minor adjustments with regard to heat accumulation will be made in future studies.

Laboratory measurement of the interface pressures applied by active therapy support surfaces : A consensus document

A key element in pressure ulcer prevention and management is the selection of appropriate pressure redistributing (PR) patient support surfaces for use while seated and in bed. However little explicit guidance exists allowing standardised quantitative comparison of different PR surfaces based upon their ability to redistribute pressure from anatomical landmarks such as the heels and sacrum. In 2008 a working group was established in Europe through the US National Pressure Ulcer Advisory Panel (NPUAP) support surface standardisation initiative (S3I) and under the aegis of the European Pressure Ulcer Advisory Panel with the specific remit of developing test methods for the evaluation of active therapy support surfaces (alternating pressure air mattresses). This report describes a consensus development process to agree test methods appropriate to compare active therapy surfaces based upon their ability to redistribute pressure from the sacrum and the heels.

Volatile Emissions from Compressed Tissue

Since almost every fifth patient treated in hospital care develops pressure ulcers, early identification of risk is important. A non-invasive method for the elucidation of endogenous biomarkers related to pressure ulcers could be an excellent tool for this purpose. We therefore found it of interest to determine if there is a difference in the emissions of volatiles from compressed and uncompressed tissue. The ultimate goal is to find a non-invasive method to obtain an early warning for the risk of developing pressure ulcers for bed-ridden persons. Chemical analysis of the emissions, collected in compresses, was made with gas-chromatography – mass spectrometry and with a chemical sensor array, the so called electronic nose. It was found that the emissions from healthy and hospitalized persons differed significantly irrespective of the site. Within each group there was a clear difference between the compressed and uncompressed site. Peaks that could be certainly deemed as markers of the compression were, however, not identified. Nonetheless, different compounds connected to the application of local mechanical pressure were found. The results obtained with GC-MS reveal the complexity of VOC composition, thus an array of non-selective chemical sensors seems to be a suitable choice for the analysis of skin emission from compressed tissues; it may represent a practical instrument for bed side diagnostics. Results show that the adopted electronic noses are likely sensitive to the total amount of the emission rather than to its composition. The development of a gas sensor-based device requires then the design of sensor receptors adequate to detect the VOCs bouquet typical of pressure. This preliminary experiment evidences the necessity of studies where each given person is followed for a long time in a ward in order to detect the insurgence of specific VOCs pattern changes signalling the occurrence of ulcers.

The Effects of Different Lying Positions on Interface Pressure, Skin Temperature, and Tissue Blood Flow in Nursing Home Residents

Background: Although repositioning is considered an important intervention to prevent pressure ulcers, tissue response during loading in different lying positions has not been adequately explored. Aim: To compare the effects of different lying positions on interface pressure, skin temperature, and tissue blood flow in nursing home residents. Method: From May 2011 to August 2012, interface pressure, skin temperature, and blood flow at three tissue depths were measured for 1 hr over the sacrum in 30° supine tilt and 0° supine positions and over the trochanter major in 30° lateral and 90° lateral positions in 25 residents aged 65 years or older. Measurement of interface pressure was accomplished using a pneumatic pressure transmitter connected to a digital manometer, skin temperature using a temperature sensor, and blood flow using photoplethysmography and laser Doppler flowmetry. Results: Interface pressure was significantly higher in the 0° supine and 90° lateral positions than in 30° supine tilt and 30° lateral positions. The mean skin temperature increased from baseline in all positions. Blood flow was significantly higher in the 30° supine tilt position compared to the other positions. A hyperemic response in the post pressure period was seen at almost all tissue depths and positions. Conclusion: The 30° supine tilt position generated less interface pressure and allowed greater tissue perfusion, suggesting that this position is the most beneficial.

The Karen instruments for measuring quality of nursing care: construct validity and internal consistency

BACKGROUND Valid and reliable instruments for measuring the quality of care are needed for evaluation and improvement of nursing care. Previously developed and evaluated instruments, the Karen-patient and the Karen-personnel based on Donabedians Structure-Process-Outcome triad (S-P-O triad) had promising content validity, discriminative power and internal consistency. OBJECTIVE The objective of this study was to further develop the instruments with regard to construct validity and internal consistency. DESIGN AND SETTING This prospective study was carried out in medical and surgical wards at a hospital in Sweden. A total of 95 patients and 120 personnel were included. METHODS The instruments were tested for construct validity by performing factor analyses in two steps and for internal consistency using Cronbachs alpha coefficient. RESULTS The first confirmatory factor analyses, with a pre-determined three-factor solution did not load well according to the S-P-O triad, but the second exploratory factor analysis with a six-factor solution appeared to be more coherent and the distribution of variables seemed to be logical. The reliability, i.e. internal consistency, was good in both factor analyses. CONCLUSIONS The Karen-patient and the Karen-personnel instruments have achieved acceptable levels of construct validity. The internal consistency of the instruments is good. This indicates that the instruments may be suitable to use in clinical practice for measuring the quality of nursing care.