Backrest Elevation and Tissue Interface Pressure by Anatomical Location During Mechanical Ventilation

The theory and practice of pressure ulcer/injury risk assessment: a critical discussion

Pressure ulcer/injury (PU) risk assessment is widely considered an essential component in clinical practice. It is a complex and broad concept that includes different approaches, such as clinical judgement, using standardised risk assessment instruments, skin assessments, or using devices to measure skin or tissue properties. A distinction between PU risk assessment and early detection is important. PU risk measures the individual's susceptibility to developing a PU under a specific exposure (primary prevention), and early detection includes the assessment of early (sub)clinical signs and symptoms to prevent progression and to support healing (secondary prevention). PU risk is measured using prognostic/risk factors or prognostic models. Every risk estimate is a probability statement containing varying degrees of uncertainty. It therefore follows that every clinical decision based on risk estimates also contains uncertainty. PU risk assessment and prevention is a complex intervention, where delivery contains several interacting components. There is a huge body of evidence indicating that risk assessment and its outcomes, the selection of preventive interventions and PU incidence are not well connected. Methods for prognostic model development and testing in PU risk research must be improved and follow state-of-the-art methodological standards. Despite these challenges, we do have substantial knowledge about PU risk factors that helps us to make better clinical decisions. An important next step in the development of PU risk prediction might be the combination of clinical and other predictors for more individualised care. Any prognostic test or procedure must lead to better prevention at an acceptable cost.

Pressure ulcer incidence in critically ill patients: Role of body mass index, nutrition therapy, and other non-nutritional factors

OBJECTIVE

To assess the clinical and nutritional risk factors related to the occurrence of pressure ulcers (PUs) in patients admitted to an Intensive Care Unit (ICU).

METHODS

This is a cohort retrospective study, carried out by analyzing the medical records of patients admitted to the ICU of a hospital, containing information on sociodemographic, clinical, dietary, and anthropometric data, presence of mechanical ventilation, sedation, and use of noradrenaline. To verify the clinical and nutritional risk factors, multivariate Poisson's regression with robust variance was used to estimate the relative risk (RR) according to the explanatory variables.

RESULTS

A total of 130 patients were evaluated from January 1 to December 31, 2019. The incidence of PUs in the study population was 29.2%. In univariate analysis, male sex, suspended or enteral diet, use of mechanical ventilation, and sedatives had a significant association with the PUs (p < 0.05). However, when adjusted for potential confounders, only suspended diet remained associated with the PUs. Furthermore, in an analysis stratified by hospitalization time, it was observed that for each 1 kg/m² increase in body mass index, there is a 10% increased risk of PUs occurrence (RR: 1.10; 95%CI: 1.01-1.23).

CONCLUSION

Patients with suspended diet, diabetics, with longer-time hospitalization, and overweight have a higher risk of presenting pressure ulcers.

Implementation of Pressure Injury Prevention Strategies in Acute Care: Results From the 2018-2019 International Pressure Injury Prevalence Survey

PURPOSE

The purpose of this study was to evaluate the implementation of pressure injury (PI) prevention strategies in adult acute care settings in the United States using the data from the 2018/2019 International Pressure Ulcer Prevalence (IPUP) Survey.

DESIGN

Observational, cohort study with cross-sectional data collection and retrospective data analysis.

SUBJECTS AND SETTING

The sample comprised 296,014 patients hospitalized in 1801 acute care facilities in the United States that participated in the 2018 and/or 2019 IPUP Survey. Slightly less than half (49.4%, n = 146,231) were male, 50% (n = 148,997) were female, 0.6% (n = 17,760) were unknown. Their mean age was 64.29 (SD 17.2) years.

METHODS

Data from the 2018/2019 IPUP database were analyzed to evaluate the implementation of prevention strategies including repositioning, support surface use, head-of-bed (HOB) elevation, heel elevation, moisture management, minimizing linen layers, and nutritional support. Practices were analyzed for differences between patients without pressure injuries, and patients with Stage 1 and 2 hospital-acquired pressure injury (HAPI), and those with severe HAPIs (Stage 3, Stage 4, unstageable, and deep tissue pressure injury). Acute care unit types included critical or intensive care units, medical-surgical inpatient care units, and step-down units.

RESULTS

Compliance rates to PI prevention strategies varied among patients at risk for HAPIs (Braden Scale for Pressure Sore Risk score ≤18). Daily skin assessment was performed for 86% of patients with no HAPIs and 96.8% of patients with severe HAPIs. Pressure redistribution was used in 74.6% of all patients and in over 90% of patients with severe HAPIs; however, compliance to routine repositioning was reported at lower levels between 67% and 84%, respectively. Heel elevation was reported for over 60% of the patients with severe HAPIs while 31.9% did not receive heel elevation, though only 6% were reported as not needing elevation. The majority of patients had HOB greater than the 30° at the time of the data collection; compliance with minimizing linen layers (≤3) was reported in 76% or more. Moisture management strategies were reportedly used in more than 71% of all patients and 89% for patients with severe HAPIs. Nutrition support was used for 55% to 82% of the patients and only documented as contraindicated in fewer than 2% of all groups.

CONCLUSION

Study findings revealed substantial compliance rates to PI prevention strategies. Nevertheless, there is potential for improvement in the implementation of some of the most basic prevention strategies including repositioning, heel elevation, nutritional support, and moisture management.

Backrest elevation in the semi-lateral position: Case of a sacral pressure ulcer with undermining formation

Backrest elevation for a patient with a sacral-coccygeal pressure ulcer is necessary in certain situations, particularly to enable the patient to take meals. Deep pressure ulcers with undermining formations affect patients and create challenges for caregivers. The procedure of backrest elevation potentially worsens the pre-existing sacral-coccygeal pressure ulcers with undermining formations. Here, we report a Case of the clinical care of a patient using a simple approach for backrest elevation that minimizes additional injury to the existing sacral pressure ulcer covered with granulation tissue. In this case, we performed the backrest elevation in the semi-lateral position. After the backrest elevation, the patient was repositioned to the supine position to take a meal. The supine position was allowed at any time except during backrest elevation. The pressure ulcer of the patient improved rapidly using the combined treatment of our positioning approach and appropriate topical ointments. This practical approach may be effective for some patients as it potentially decreases the effect of shear force. The rationale for this approach can be explained by the mechanism of the undermining formation outlined in our experimental study using a pressure ulcer model mounted to a phantom. Although we used this position for patients with sacral-coccygeal pressure ulcers, this simple approach may also be considered for other patients based on our proposed pathogenesis of undermining formations.

Friction characteristics of preventative wound dressings under clinically-relevant conditions

Wound dressings can be used prophylactically or during actual treatment. Preventative dressings have become a standard of care to prevent pressure ulcers in patients while in bed. While the mechanism of the preventative benefit has not been completely explained, the friction between the dressing and linen is hypothesized as being a key performance factor. The objective of this project was to quantify the static and kinetic coefficients of friction (COF) of various brands of prophylactic dressings under the stresses experienced in situ, while the dressings are in contact with bed linen materials. The COF of six commercial dressings were calculated using tribometer measurements. The ranges of static COF were 0.333-0.542 and kinetic COF were 0.333-0.513. Four dressings exhibited COF that were consistent with skin-linen values reported in the literature and all dressing COF appear to be lower than the COF of moist skin against linen.

OR Time and Sacral Pressure Injuries in Critically Ill Surgical Patients

Critically ill patients are at risk for developing pressure injuries during operative and other invasive procedures. The purpose of this secondary analysis was to explore the relationship of OR time to sacral pressure injuries in critically ill patients using high frequency ultrasound as a method of assessment. The 41 participants examined in this study had both time in the OR and up to eight days of pressure injury data. The multivariable model containing OR bed time, body mass index, and Braden Scale score produced the best prediction of pressure injury (area under the curve = 0.859). A higher body mass index (P = .09), shorter OR bed time (P = .01), and lower Braden Scale score (P = .05) were associated with a greater chance of pressure injury. These results suggest that use of high frequency ultrasound may identify tissue changes before observable skin changes, leading to earlier pressure injury prevention strategies.

The mechanism of persistent undermining of a sacral pressure ulcer: Experimental analyses using a deformable model and examination of skin mobility over different anatomical locations

Undermining is an important issue in the treatment and care of deep pressure ulcers. The frequency of the undermining over different bony prominences varies. In particular, deep pressure ulcers over the sacrum exhibit undermining more frequently than those occurring over the heel. Although shear force has been suggested as a critical factor in undermining, the exact mechanism remains unclear due to ethical and technical reasons in clinical practice. To clarify this issue, a deformable model was constructed to recreate the physical and morphological properties of a pressure ulcer with persistent undermining. The model was constructed using urethane to recreate the physical properties of a pressure ulcer. To examine the clinical relevance of the model, mechanical properties of the skin and the model were measured using a durometer. The model was further mounted onto a phantom that was laid on a bed. Backrest elevation of the bed induced deformities in the urethane model, suggesting a mechanism of persistent undermining of the sacral pressure ulcer. Moreover, a simple palpation examination in elderly volunteers revealed that the skin over the sacrum was more mobile than the skin over the heel. Therefore, persistent undermining is likely caused by specific external forces and the characteristic skin mobility of the sacral region. These two different factors explain the frequent undermining that occurs in sacral pressure ulcers.

Visualizing Tissue Strain Under the Sacrum and Coccyx in Different Supine Postures: A Case Series

OBJECTIVE

To visually assess and report the influence of supine positioning and sacrum and coccyx anatomy on tissue deformation.

METHODS

A convenience sample of three participants was scanned using MRI. All participants were scanned in a supine position with a rig oriented in a flat or horizontal position and with the torso portion of the rig elevated to 30° to simulate head-of-bed elevation. Representative images were identified to visualize and depict (1) the differences in tissue thickness and deformation in response to changes in supine positioning (0° and 30°), (2) the relative displacement of the skeleton relative to the skin during 30° incline, and (3) differences in sacrococcygeal morphology.

RESULTS

The tissue thickness under the sacrum stayed the same or increased when torsos were elevated. Skeletons were displaced relative to the skin when the rig was elevated regardless of the pelvis location. Further, in the elevated position, coccyges flexed when pelvises were placed on the elevated segment but did not flex when pelvises were placed on the horizontal segment.

CONCLUSIONS

This case series is useful in defining new areas of research that can (1) identify the deformation induced by normal and frictional forces resulting from different positions of the bed chassis, (2) assess the impact of positioning the pelvis on elevated versus horizontal segments of the bed chassis, and (3) define the association between sacral and coccyx morphology and pressure ulcer occurrence in hospitalized patients.

High-Frequency Ultrasound: Obtaining Optimal Images and the Effect of Image Artifacts on Image Quality

Objective: High-frequency ultrasound (HFUS) images are being researched for use in the prevention, detection, and monitoring of pressure injuries in patients at risk. This seminal longitudinal study in mechanically ventilated adults describes image quality, the incidence of image artifacts, and their effect on image quality in critically ill subjects. Approach: Mechanically ventilated subjects from three adult intensive care units were enrolled, and multiple sacral images from each subject were obtained daily. Using a subset of best image per patient per day, artifacts were grouped, and their effect on image quality was statistically evaluated. Results: Of a total of 1761 images collected from 137 subjects, 8% were rated as poor. In the subset, 70% had good quality ratings. Four groups of artifacts were identified as follows: "bubbles," "texture problems," "layer nondifferentiation," and "reduced area for evaluation." Artifacts from at least one group were found in 83% of images. Bubbles were most frequently seen, but artifacts with adverse effect on image quality were "layer nondifferentiation," "texture problems," and "reduced area for evaluation." Innovation: HFUS image evaluation is still in the development phase with respect to tissue injury use. Artifacts are generally omnipresent. Quickly recognizing artifacts that most significantly affect image quality during scanning will result in higher quality images for research and clinical applications. Conclusion: Good quality images were achievable in study units; although frequent artifacts were present in images, in general, they did not interfere with evaluation. Artifacts related to "layer nondifferentiation" was the greatest predictor of poor image quality, prompting operators to immediately rescan the area.

High frequency ultrasound sacral images in the critically ill: Tissue characteristics versus visual evaluation

PURPOSE

High frequency ultrasound (HFUS) systems may identify tissue injury. We compared HFUS tissue characteristics (dermal thickness and dermal density) with visual image examination.

METHODS

Longitudinal study in critically ill mechanically ventilated adults, from three ICUs (Surgical Trauma, Medical Respiratory, Neuroscience) enrolled within 24hours of airway intubation. Sacral HFUS images were obtained daily for up to seven days. Expert evaluation of the best image per day was completed and compared to HFUS generated tissue characteristics (dermal thickness and dermal density).

RESULTS

Of the113 subjects with 1614 comparisons analysed, 73.2% to 84% were normal, and 6.3% to 11.8% of the comparisons had injury present but no change was noted in the injury observed. There were no significant differences in one-day comparisons among type of injury and mean dermal thickness (p=0.6645) or dermal median intensity (adjusted p=0.06-0.17). All other day-to-day comparisons were similarly non-significant.

CONCLUSIONS

We found no association among dermal density, dermal thickness and visual examination of changes in sacral HFUS images for any day-to-day comparison. The use of sacral HFUS as a screening tool for the development of tissue injury is in its infancy. Additional comparative studies should be conducted to identify its future clinical usefulness.

Tissue interface pressure and skin integrity in critically ill, mechanically ventilated patients

OBJECTIVE

To describe tissue interface pressure, time spent above critical pressure levels and the effect on skin integrity at seven anatomical locations.

DESIGN, SETTING, PATIENTS

Descriptive, longitudinal study in critically ill mechanically ventilated adults, from Surgical Trauma ICU-STICU; Medical Respiratory ICU-MRICU; Neuroscience ICU-NSICU in a Mid-Atlantic urban university medical centre. Subjects were enroled in the study within 24hours of intubation.

MEASUREMENTS

Tissue interface pressure was measured continuously using the XSENSOR pressure mapping system (XSENSOR Technology Corporation, Calgary, Canada). Skin integrity was observed at all sites, twice daily, using the National Pressure Ulcer Advisory Panel staging system, for the first seven ICU days and at day 10 and 14.

RESULTS

Of the 132 subjects, 90.9% had no observed changes in skin integrity. Maximum interface pressure was above 32mmHg virtually 100% of the time for the sacrum, left and right trochanter. At the 45mmHg level, the left and right trochanter had the greatest amount of time above this level (greater than 95% of the time), followed by the sacrum, left and right scapula, and the left and right heels. Similarly, at levels above 60mmHg, the same site order applied. For those six subjects with sacral skin integrity changes, maximum pressures were greater than 32mmHg 100% of the time. Four of the six sacral changes were associated with greater amounts of time above both 45mmHg and 60mmHg than the entire sample.

CONCLUSIONS

Maximum tissue interface pressure was above critical levels for the majority of the documented periods, especially in the sacrum, although few changes in skin integrity were documented. Time spent above critical levels for mean pressures were considerably less compared to maximum pressures. Maximum pressures may have reflected pressure spikes, but the large amount of time above the critical pressure levels remains substantial.