Claire E. Baldwin

Expert consensus and recommendations on safety criteria for active mobilization of mechanically ventilated critically ill adults.

IntroductionThe aim of this study was to develop consensus recommendations on safety parameters for mobilizing adult, mechanically ventilated, intensive care unit (ICU) patients.MethodsA systematic literature review was followed by a meeting of 23 multidisciplinary ICU experts to seek consensus regarding the safe mobilization of mechanically ventilated patients.ResultsSafety considerations were summarized in four categories: respiratory, cardiovascular, neurological and other. Consensus was achieved on all criteria for safe mobilization, with the exception being levels of vasoactive agents. Intubation via an endotracheal tube was not a contraindication to early mobilization and a fraction of inspired oxygen less than 0.6 with a percutaneous oxygen saturation more than 90% and a respiratory rate less than 30 breaths/minute were considered safe criteria for in- and out-of-bed mobilization if there were no other contraindications. At an international meeting, 94 multidisciplinary ICU clinicians concurred with the proposed recommendations.ConclusionConsensus recommendations regarding safety criteria for mobilization of adult, mechanically ventilated patients in the ICU have the potential to guide ICU rehabilitation whilst minimizing the risk of adverse events.

Muscle strength assessment in critically ill patients with handheld dynamometry: An investigation of reliability, minimal detectable change, and time to peak force generation

PURPOSE Dynamometry is an objective tool for volitional strength evaluation that may overcome the limited sensitivity of the Medical Research Council scale for manual muscle tests, particularly at grades 4 and 5. The primary aims of this study were to investigate the reliability, minimal detectable change, and time to peak muscle force, measured with portable dynamometry, in critically ill patients. MATERIALS AND METHODS Isometric hand grip, elbow flexion, and knee extension were measured with portable dynamometry. RESULTS Interrater consistency (intraclass correlation coefficient [95% confidence interval]) (0.782 [0.321-0.930] to 0.946 [0.840-0.982]) and test-retest agreement (0.819 [0.390-0.943] to 0.918 [0.779-0.970]) were acceptable for all dynamometry forces, with the exception of left elbow flexion. Despite generally good reliability, a mean change (upper 95% confidence interval) of 2.8 (7.8) kg, 1.9 (5.2) kg, and 2.6 (7.1) kg may be required from a patients baseline force measurement of right grip, elbow flexion, and knee extension to reflect real force changes. There was also a delay in the time for critically ill patients to generate peak muscle forces, compared with healthy controls (P ≤ .001). CONCLUSIONS Dynamometry can provide reliable measurements in alert critically ill patients, but moderate changes in strength may be required to overcome measurement error, during the acute recovery period. Deficits in force timing may reflect impaired neuromuscular control.

Diaphragm and peripheral muscle thickness on ultrasound: Intra‐rater reliability and variability of a methodology using non‐standard recumbent positions

Background and objective:  Reliable measurement of diaphragm and peripheral muscle thickness, using diagnostic ultrasound, has only been validated in the erect posture. However, in many clinical populations, including critically ill patients, the erect posture presents logistic difficulties. This study aimed to validate ultrasound measurement of diaphragm and peripheral muscle thickness in the recumbent position.

Factors influencing physical activity and rehabilitation in survivors of critical illness: a systematic review of quantitative and qualitative studies

PurposeTo identify, evaluate and synthesise studies examining the barriers and enablers for survivors of critical illness to participate in physical activity in the ICU and post-ICU settings from the perspective of patients, caregivers and healthcare providers.MethodsSystematic review of articles using five electronic databases: MEDLINE, CINAHL, EMBASE, Cochrane Library, Scopus. Quantitative and qualitative studies that were published in English in a peer-reviewed journal and assessed barriers or enablers for survivors of critical illness to perform physical activity were included. Prospero ID: CRD42016035454.ResultsEighty-nine papers were included. Five major themes and 28 sub-themes were identified, encompassing: (1) patient physical and psychological capability to perform physical activity, including delirium, sedation, illness severity, comorbidities, weakness, anxiety, confidence and motivation; (2) safety influences, including physiological stability and concern for lines, e.g. risk of dislodgement; (3) culture and team influences, including leadership, interprofessional communication, administrative buy-in, clinician expertise and knowledge; (4) motivation and beliefs regarding the benefits/risks; and (5) environmental influences, including funding, access to rehabilitation programs, staffing and equipment.ConclusionsThe main barriers identified were patient physical and psychological capability to perform physical activity, safety concerns, lack of leadership and ICU culture of mobility, lack of interprofessional communication, expertise and knowledge, and lack of staffing/equipment and funding to provide rehabilitation programs. Barriers and enablers are multidimensional and span diverse factors. The majority of these barriers are modifiable and can be targeted in future clinical practice.

Body composition analysis in critically ill survivors: a comparison of bioelectrical impedance spectroscopy devices.

BACKGROUND Body composition is commonly altered in response to critical illness and can be estimated at the bedside with bioelectrical impedance spectroscopy (BIS). Different electrode configurations may be used to mitigate assumptions of the technique, but the reliability of tetra-polar and octo-polar arrangements has yet to be established. This study aimed to compare both configurations, in a prospective observational study of 17 critically ill survivors and 12 healthy controls. METHODS Weight, supine body length, and BIS on both tetra-polar and octo-polar configured devices were recorded, then repeated 2 days later. Bioelectrical impedance vector analysis was subsequently performed using data from the tetra-polar device at a frequency of 50 kHz. RESULTS Test-retest agreement was acceptable for the tetra-polar device (intraclass correlation coefficient range, patients: 0.876-0.988 vs controls: 0.983-0.998, P ≤ 0.001). However, lower and wider ranging test-retest intraclass correlation coefficients were obtained with the octo-polar instrument in both groups. Furthermore, there was a difference in the mass/volume of body compartments measured on each device in both patients (P ≤ .017) and controls (P ≤ .045). A change in the composition profile of critically ill males was evident between measurement occasions, which was reflected by a reduction in body weight of 1.6 (1.5) kg (P ≤ 0.001) across the sample over the same period. CONCLUSIONS BIS devices should not be used interchangeably in the clinical setting. The reliability of the tetra-polar instrument was good, but daily fluctuations in body weight may have affected the results.

Tracheostomy Tube Type and Inner Cannula Selection Impact Pressure and Resistance to Air Flow

BACKGROUND: Advancements in tracheostomy tube design now provide clinicians with a range of options to facilitate communication for individuals receiving ventilator assistance through a cuffed tube. Little is known about the impact of these modern design features on resistance to air flow. METHODS: We undertook a bench model test to measure pressure-flow characteristics and resistance of a range of tubes of similar outer diameter, including those enabling subglottic suction and speech. A constant inspiratory ± expiratory air flow was generated at increasing flows up to 150 L/min through each tube (with or without optional, mandatory, or interchangeable inner cannula). Driving pressures were measured, and resistance was calculated (cm H2O/L/s). RESULTS: Pressures changed with increasing flow (P < .001) and tube type (P < .001), with differing patterns of pressure change according to the type of tube (P < .001) and direction of air flow. The single-lumen reference tube encountered the lowest inspiratory and expiratory pressures compared with all double-lumen tubes (P < .001); placement of an optional inner cannula increased bidirectional tube resistance by a factor of 3. For a tube with interchangeable inner cannulas, the type of cannula altered pressure and resistance differently (P < .001); the speech cannula in particular amplified pressure-flow changes and increased tube resistance by more than a factor of 4. CONCLUSIONS: Tracheostomy tube type and inner cannula selection imposed differing pressures and resistance to air flow during inspiration and expiration. These differences may be important when selecting airway equipment or when setting parameters for monitoring, particularly for patients receiving supported ventilation or during the weaning process.

Physical Activity of ICU Survivors during Acute Admission: Agreement of the activPAL with Observation

Purpose: We estimated the agreement of a thigh-worn accelerometer, the activPAL, used to measure activity and sedentary parameters, with observed mobility assessments of intensive care unit (ICU) survivors. Method: We prospectively compared activPAL measurements with direct observation during assessments at discharge from the ICU or acute hospital in eight participants with a median age of 56 (1st-3rd quartile 48-65) years and an Acute Physiology and Chronic Health Evaluation II score of 23 (1st-3rd quartile 17-24). Frequency of sit-to-stand transitions; time spent standing, stepping, upright (standing and stepping), and sedentary (lying/sitting); and total steps were described; analysis was performed using Bland-Altman plots and calculating the absolute percent error. Results: All sit-to-stand transitions were accurately detected. The mean difference on the Bland-Altman plots suggested an overestimation of standing time with the activPAL of 31 (95% CI: -9, 71) seconds and underestimation of stepping time by 25 (95% CI: -47, -3) seconds. The largest median absolute percent errors were for standing time (21.9%) and stepping time (18.7%); time spent upright (1.7%) or sedentary (0.3%) was more accurately estimated. The activPAL underestimated total steps per session, achieving the largest percent error (70.8%). Conclusion: Because it underestimated step count, the activPAL likely incorrectly recorded stepping time as standing time, so that time spent upright was the measure of activity with the smallest error. Sedentary behaviour, including frequency of transitions, was validly assessed.

Myopathic characteristics in septic mechanically ventilated patients.

Purpose of reviewSurvivors of a critical illness may experience poor physical function and quality of life as a result of reduced skeletal muscle mass and strength during their acute illness. Patients diagnosed with sepsis are particularly at risk, and mechanical ventilation may result in diaphragm dysfunction. Interest in the interaction of these conditions is both growing and important to understand for individualized patient care. Recent findingsThis review describes developments in the presentation of both diaphragm and limb myopathy in critical illness, as measured from muscle biopsy and at the bedside with various imaging and strength-testing modalities. The influence of unloading of the diaphragm with mechanical ventilation and peripheral muscles with immobilization in septic patients has been recently questioned. Systemic inflammation appears to primarily accelerate and accentuate dysfunction, which may be remedied by early mobilization and augmented with developing muscle and/or nerve stimulation techniques. SummaryMany acute muscle changes in septic patients are likely to stem from pre-existing impairments, which should provide context for clinical evaluations of strength. During illness, sarcolemmal injury promotes a cascade of intra-cellular abnormalities. As unique characteristics of ICU-acquired weakness and differential effects on muscle groups are understood, early diagnosis and management should be facilitated.