Ruth S. Burk

Backrest position in prevention of pressure ulcers and ventilator-associated pneumonia: Conflicting recommendations

Pressure ulcers and ventilator-associated pneumonia (VAP) are both common in acute and critical care settings and are considerable sources of morbidity, mortality, and health care costs. To prevent pressure ulcers, guidelines limit bed backrest elevation to less than 30 degrees, whereas recommendations to reduce VAP include use of backrest elevations of 30 degrees or more. Although a variety of risk factors beyond patient position have been identified for both pressure ulcers and VAP, this article will focus on summarizing the major evidence for each of these apparently conflicting positioning strategies and discuss implications for practice in managing mechanically ventilated patients with risk factors for both pressure ulcers and VAP.

Utility of high-frequency ultrasound: moving beyond the surface to detect changes in skin integrity.

Ultrasound imaging is a versatile modality frequently used in clinical medicine, most likely due to its low cost, low risk to patients, and the ability to provide images in real time. Ultrasound used typically in clinical settings has frequencies between 2 and 12 MHz. Lower frequencies produce greater resolution but are limited in depth penetration; higher frequencies produce greater resolution, but depth of penetration is limited. High-frequency ultrasound (HFUS) shows promise for detection of certain changes in the skin and this has implications for early detection of changes associated with pressure ulcer formation and wound healing. The purpose of this article was to provide an overview of where HFUS has been used with the skin and provide some discussion on its utility with detecting skin changes related to pressure.

Predictors of Agitation in Critically Ill Adults

BACKGROUND Agitation in critically ill adults is a frequent complication of hospitalization and results in multiple adverse outcomes. Potential causes of agitation are numerous; however, data on factors predictive of agitation are limited. OBJECTIVES To identify predictors of agitation by examining demographic and clinical characteristics of critically ill patients. METHODS A medical record review was performed. Documentation of agitation was indicated by scores on the Richmond Agitation-Sedation Scale or the use of an agitation keyword. Records of 200 patients from 1 medical and 1 surgical intensive care unit were used for the study. Risk factors were determined for 2 points in time: admission to the intensive care unit and within 24 hours before the first episode of agitation. Data on baseline demographics, preadmission risk factors, and clinical data were collected and were evaluated by using logistic multivariable regression to determine predictors of agitation. RESULTS Predictors of agitation on admission to intensive care were history of use of illicit substances, height, respiratory and central nervous system subscores on the Sequential Organ Failure Assessment, and use of restraints. Predictors of agitation within 24 hours before the onset of agitation were history of psychiatric diagnosis, height, score on the Sequential Organ Failure Assessment, ratio of Pao2 to fraction of inspired oxygen less than 200, serum pH, percentage of hours with restraints, percentage of hours of mechanical ventilation, pain, and presence of genitourinary catheters. CONCLUSIONS Predictors of agitation on admission and within 24 hours before the onset of agitation were primarily clinical variables.

Agitation Onset, Frequency, and Associated Temporal Factors in Critically Ill Adults

BACKGROUND Agitation is a frequent complication in critically ill adults, can result in life-threatening events for patients or care providers, and extends the hospital length of stay, thereby increasing hospital costs. OBJECTIVES To describe the incidence, onset, and temporal factors related to agitation in critically ill adults. METHODS Data were collected for the first 5 days of stay of all adult patients consecutively admitted to a medical respiratory intensive care unit and a surgical trauma intensive care unit during a 2-month period. Agitation was documented by using scores on the Richmond Agitation-Sedation Scale or notation of agitation in the medical record. The hour was used as the documentation epoch, and data were summarized by hour, 4-hour block, and day for each patient. RESULTS Data were collected on 200 patients, 100 from each unit. Among the sample, 118 (59%) were agitated at some time during the 5 days. The overall agitation rate was 7.8% of the total hourly time. Mean onset of agitation was 11.6 hours from time of admission to the unit. Of the 118 patients who were agitated at some time, 102 (86%) had agitation on day 1. Compared with patients in the surgical trauma unit, patients in the medical respiratory unit had significantly more hours of agitation the first day and first hour of admission and significantly earlier onset of agitation. CONCLUSIONS Agitation was present in more than one-half of the patients in the sample, typically developed on the first day, and involved consecutive days.

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.

Use of high frequency ultrasound to detect changes in skin integrity: An image evaluation validation procedure

OBJECTIVES High frequency ultrasound (HFUS) scanning may be used for prevention, detection and monitoring of pressure ulcers in patients at risk and is amenable for portable, bedside use by a variety of clinicians. Limited data are available about the criteria to determine an ideal image or measures of tissue changes representative of tissue injury. We developed and evaluated criteria for overall image quality and measures of tissue integrity. METHODS In 40 mechanically ventilated adults in 3 ICUs, 241 HFUS sacral images were evaluated for agreement using criteria for overall image quality and tissue changes (dermal, hypodermal layer thickness and layer density). RESULTS HFUS sacral images (N=241) were evaluated in three analyses and showed poor agreement in all three analyses using the specific criteria for global quality, however when criteria were collapsed agreement was good to substantial. Evaluator agreement for layer thickness and layer density was also good. CONCLUSIONS A global rating is adequate for identifying good images. Agreement for measurements of layer thickness and density were also good and may be useful to identify early changes in tissue integrity leading to tissue injury. Additional data are needed concerning the association of changes in layer thickness and layer density to eventual tissue injury.

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

BACKGROUND Backrest elevations less than 30° are recommended to reduce pressure ulcers, but positions greater than 30° are recommended during mechanical ventilation to reduce risk for ventilator-associated pneumonia. Interface pressure may vary with level of backrest elevation and anatomical location (eg, sacrum, heels). OBJECTIVE To describe backrest elevation and anatomical location and intensity of skin pressure across the body in patients receiving mechanical ventilation. METHODS In a longitudinal study, patients from 3 adult intensive care units in a single institution receiving mechanical ventilation were enrolled within 24 hours of intubation from February 2010 through May 2012. Backrest elevation (by inclinometer) and pressure (by a pressure-mapping system) were measured continuously for 72 hours. Mean tissue interface pressure was determined for 7 anatomical areas: left and right scapula, left and right trochanter, sacrum, and left and right heel. RESULTS Data on 133 patients were analyzed. For each 1° increase in backrest elevation, mean interface pressure decreased 0.09 to 0.42 mm Hg. For each unit increase in body mass index, mean trochanter pressure increased 0.22 to 0.24 mm Hg. Knee angle (lower extremity bent at the knee) and mobility were time-varying covariates in models of the relationship between backrest elevation and tissue interface pressure. CONCLUSIONS Individual factors such as patient movement and body mass index may be important elements related to risk for pressure ulcers and ventilator-associated pneumonia, and a more nuanced approach in which positioning decisions are tailored to optimize outcomes for individual patients appears warranted.

Effects of position and operator on high-frequency ultrasound scan quality ☆

OBJECTIVES High-frequency ultrasound may evaluate those at risk for pressure ulcers. Images may be obtained by clinicians with limited training. The prone position is recommended for obtaining sacral scans but may not be feasible in the critically ill. This study investigated image quality using multiple operators and a variety of patient positions. RESEARCH METHODOLOGY Sacral scans were performed in three randomised positions in 50 volunteers by three different investigators using a 20 MHz ultrasound system. General linear models and ANOVA random effects models were used to examine the effects of operator and position on image quality rating, and measures of dermal thickness and dermal density. RESULTS The best scan for each position and operator was used for analysis (n=447 images). Image rating varied by operator (p=0.0004), although mean ratings were 3.5 or above for all operators. Dermal thickness was less for the prone position than in 90° or 60° side-lying positions (p=0.0137, p=0.0003). Dermal density was lower for the prone position than for the 90° or 60° positions (p<0.0001 for both). CONCLUSIONS These data show that overall scan quality was acceptable in all positions with all operators. However, differences were found between side-lying positions and the prone for dermal thickness and dermal density measures.

High-Frequency Ultrasound: Description of Sacral Tissue Characteristics in Healthy Adults

OBJECTIVES: The purpose of this study was to describe selected sacral tissue characteristics in a convenience sample of healthy volunteer subjects. DESIGN: Descriptive. SAMPLE AND SETTING: Fifty healthy volunteers in a clinical learning center in a school of nursing. METHODS: Sacral scans were obtained using a 20-MHz ultrasound scanning system in 3 positions: prone and 60° and 90° side-lying from the back. The images were analyzed by software in the ultrasound program using quantitative parameters of dermal thickness and density (dermal median intensity and derived number of low-echogenic pixels to total pixels [LEP:TP] ratio). RESULTS: In general, average values were as follows: dermal thickness between 2.32 and 2.65 mm; median pixel intensity between 102 and 112; and the LEP:TP ratio between 0.39 and 0.56. There were significant differences in sacral tissue characteristics between measures of thickness and dermal density (median intensity and LEP:TP ratio) by subject side-lying position (60° and 90°) versus prone position, with all P values less than .0001. CONCLUSIONS: Overall, the ranges were consistent across measures of thickness and dermal density except for systematic differences between side-lying and prone positions. When comparing thickness, median intensity, or LEP:TP ratio, it is important to report subject position. To best recognize tissue inflammation indicative of pressure injuries before surface changes are seen, it is useful to understand healthy high-frequency ultrasound sacral tissue characteristics. It is anticipated that quantitative assessment of dermal thickness, density, and LEP:TP ratio could help identify individuals with incipient pressure injury.

Stimulation of Critically Ill Patients: Relationship to Sedation

OBJECTIVES To describe the number and type of stimulation events and the relationship of stimulation to sedation level in patients receiving mechanical ventilation. METHODS A 4-hour direct observation was conducted in 103 patients receiving mechanical ventilation. Stimulation events and sedation level before and after the stimulation were documented. Eight categories of stimulation events were developed in a previous pilot study of 36 patients receiving mechanical ventilation. Sedation was measured continuously by using a processed electroencephalographic score (patient state index [PSI]) and intermittently by using the Richmond Agitation-Sedation Scale. RESULTS Patients were mostly alert/mildly sedated (54.4%) at study enrollment. During the 349 hours of observation, 58.8% of the time included stimulation events. General auditory types of stimulation were most common (41.2% of observed time), followed by respiratory management and tactile family stimulation. For all events, auditory-talking, tactile-general, tactile-noxious, and tactile-highly noxious stimuli were associated with higher PSIs (all P < .001) after stimulation; other stimuli were not. Level of consciousness influenced response to stimuli, with almost all types of stimuli increasing PSI for patients more deeply sedated (PSI < 60) just before the stimuli. However, the effect of stimulation on PSI for more alert patients (PSI > 60) was small and variable. DISCUSSION Critically ill patients receiving mechanical ventilation are subjected to various forms of auditory and tactile stimulation frequently throughout the day. All types of stimuli increased arousal in patients who were more deeply sedated. The effect of stimulation in patients who were not deeply sedated was minimal and inconsistent.