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The purpose of this pilot study was to explore the utility of the mammalian swine model under simulated intensive care unit (sICU) conditions and mechanical ventilation (MV) for assessment of the trajectory of circadian rhythms of sedation requirement, core body temperature (CBT), pulmonary mechanics (PM) and gas exchange (GE). Data were collected prospectively with an observational time-series design to describe and compare circadian rhythms of selected study variables in four swine mechanically ventilated for up to seven consecutive days. We derived the circadian (total variance explained by rhythms of τ between 20 and 28 h)/ultradian (total variance explained by rhythms of τ between 1 and <20 h) bandpower ratio to assess the robustness of circadian rhythms, and compare findings between the early (first 3 days) and late (subsequent days) sICU stay. All pigs exhibited statistically significant circadian rhythms (τ between 20 and 28 h) in CBT, respiratory rate and peripheral oxygen saturation, but circadian rhythms were detected less frequently for sedation requirement, spontaneous minute volume, arterial oxygen tension, arterial carbon dioxide tension and arterial pH. Sedation did not appear to mask the circadian rhythms of CBT, PM and GE. Individual subject observations were more informative than group data, and provided preliminary evidence that (a) circadian rhythms of multiple variables are lost or desynchronized in mechanically ventilated subjects, (b) robustness of circadian rhythm varies with subject morbidity and (c) healthier pigs develop more robust circadian rhythm profiles over time in the sICU. Comparison of biological rhythm profiles among sICU subjects with similar severity of illness is needed to determine if the results of this pilot study are reproducible. Identification of consistent patterns may provide insight into subject morbidity and timing of such therapeutic interventions as weaning from MV.

A valid and reliable scale for assessing level of sedation would facilitate appropriate sedation management in a porcine intensive care unit (ICU) model. The Richmond Agitation-Sedation Scale (RASS) is used often for human ICU patients. The purpose of this study was to estimate the content validity of the modified RASS for use in sedated, mechanically ventilated swine. The modified RASS includes descriptors specific for swine. A content validity assessment form was developed with 4 items and 5 response choices to assess the modified RASS for relevancy, sufficiency, clarity, and representativeness. The modified RASS and content validity assessment form were emailed to 23 veterinarians with experience in the care of swine or other large animals; participants judged the extent to which the modified RASS is valid for assessing sedation in mechanically ventilated critically ill swine. The criterion for acceptable validity evidence was a content validity index (CVI) of 0.80 or greater. Eight (67%) of 12 veterinarians who responded to the invitation to participate completed the assessment form. The item CVI varied from 0.50 to 0.88; scale CVI was 0.66. Because these values did not meet the a priori criterion, we concluded that the modified RASS does not have sufficient evidence of content validity for use with swine. The reliability of the modified RASS will be tested in the porcine ICU model, and experience with its use in swine will inform refinement of the scale descriptors for repeat assessment of content validity.

Mechanically ventilated patients in the intensive care unit (ICU) are typically turned manually by nursing staff to reduce the risk of developing ventilator associated pneumonia and other problems in the lungs. However, turning can induce changes in the heart rate and blood pressure that can at times have a destabilizing effect. We report here on the early stage of a study that has been undertaken to measure the cardiovascular impact of manual turning, and compare it to changes induced when patients lie on automated beds that turn continuously. Heart rate and blood pressure data were analyzed over ensembles of turns with autoregressive models for comparing baseline level to the dynamic response. Manual turning stimulated a response in the heart rate that lasted for a median of 20 minutes and was of magnitude 5 to 13 bpm. The corresponding response in mean arterial pressure was 11 to 19 mm Hg, lasting for 8 to 21 minutes. There was no discernible response of either variable to automated turns.

A porcine adult ICU model would be useful for several avenues of investigation relevant to the care of critically ill patients. The purpose of the experiments reported here was to test the feasibility of such a model, using healthy swine. Swine (n = 4; body weight, 76 +/- 5 kg) were instrumented with endotracheal, bladder, and central arterial and venous catheters, and were admitted to the intensive care unit (ICU) while undergoing mechanical ventilation under the continuous care of nurses. Cardiopulmonary parameters were monitored continuously, and serum biochemical parameters were measured intermittently. Survival was seven days in subject 1 and five and a half days in subject 2. Subjects 3 and 4 survived an abbreviated protocol (44 and 41 h, respectively). Care of the subjects was complicated by iatrogenic hemorrhage (n = 3), pneumonia (n = 2), and acute respiratory distress syndrome (n = 1). One subject was free of complications. Critically ill swine > or = 70 kg can survive mechanical ventilation in the ICU for up to seven days. When iatrogenic injury occurs, swine respond well to clinical care protocols. Further testing is needed to develop a reproducible model and determine whether healthy swine can survive the ICU environment for longer than 41 h.

Background: Critical care nurses who care for postoperative cardiac surgery patients need such specialty knowledge as atrial electrograms (AEGs). An inadequate audit trail exists for psychometric performance of instruments to measure knowledge of AEGs. Objectives: The aim of this study was to revise a previously tested instrument and assess evidence for content validity (content validity index), internal consistency (Cronbach α), and stability (correlation coefficient, r) reliability against the a priori criterion of 0.80. Methods: The multiple-choice response, self-administered, paper-and-pencil instrument was revised to 20 items and named the Drake Atrial Electrogram Assessment Survey (DAEGAS). A panel of 6 AEG experts reviewed the DAEGAS for content validity evidence. The instrument was further revised to 19 items (13 knowledge and 6 AEG interpretation) and tested with 76 critical care nurses from the greater Houston metropolitan area. Results: The content validity index was 0.93. Cronbach α was.51, and test-retest r was 0.74. Cronbach α increased to.60 and r was 0.73 with removal of 3 items: 2 items with a negative item-total correlation and 1 item that was transitioned to a sample question. Discussion: Content validity evidence exceeded the a priori criterion. Internal consistency and stability reliability estimates did not meet the criterion, albeit the latter met the criterion recommended by psychometricians for a new instrument. Recommendations include further development of the DAEGAS to improve internal consistency estimates and testing for evidence of other forms of validity. Reliable and valid assessment of critical care nurse knowledge of AEGs will require improved psychometric performance of the DAEGAS. [ABSTRACT FROM AUTHOR]

Purpose To estimate effect sizes for a trial to compare preventable pulmonary complications (PPCs), turning-related adverse events, mechanical ventilation duration, intensive care unit (ICU) length of stay, and ICU mortality between patients randomized to 2-hourly manual or continuous automated lateral rotation. Methods Randomized controlled trial pilot study with 15 patients selected randomly from eligible medical-surgical ICU patients from 2 tertiary hospitals and assigned randomly to the manual-turn or automated-turn protocol for up to 7 consecutive days. A radiologist blinded to group and site assessed serial chest radiographs for PPCs. Repeated-measures analysis with linear mixed models was used to estimate change in PPC score, and Wilcoxon rank sum or Fisher exact test was used to compare group differences in the secondary outcomes. Results Of 16 patients enrolled, 12 (75%) completed the study. Data from 15 patients, 7 manual turn and 8 automated turn, were analyzed. Between-group differences in PPC incidence (67% overall), change in PPC score (β = 0.15, manual turn and β = -0.44, automated turn), and secondary outcomes were not significant (P > .05). Standardized effect sizes were small to moderate for the outcome variables. A sample size of 54 patients would be needed to detect statistically significant between-group differences in PPC over time. Conclusions The incidence of PPCs in adult patients receiving mechanical ventilation in a medical-surgical ICU was high. Automated turning decreased PPCs with time but had little effect on secondary outcomes. Safety outcomes were not substantially different between groups. A modest efficacy effect supported reduced PPCs with automated turning to the lateral position. [ABSTRACT FROM AUTHOR]