Angela T. Chang

Reduced inspiratory muscle endurance following successful weaning from prolonged mechanical ventilation.

STUDY OBJECTIVES Respiratory muscle weakness and decreased endurance have been demonstrated following mechanical ventilation. However, its relationship to the duration of mechanical ventilation is not known. The aim of this study was to assess respiratory muscle endurance and its relationship to the duration of mechanical ventilation. DESIGN Prospective study. SETTING Tertiary teaching hospital ICU. PATIENTS Twenty subjects were recruited for the study who had received mechanical ventilation for > or = 48 h and had been discharged from the ICU. MEASUREMENTS FEV1, FVC, and maximal inspiratory pressure (P(I(max)) at functional residual capacity were recorded. The P(I(max)) attained following resisted inspiration at 30% of the initial P(I(max)) for 2 min was recorded, and the fatigue resistance index (FRI) [P(I(max)) final/P(I(max))initial] was calculated. The duration of ICU length of stay (ICULOS), duration of mechanical ventilation (MVD), duration of weaning (WD), and Charlson comorbidities score (CCS) were also recorded. Relationships between fatigue and other parameters were analyzed using the Spearman correlations (rho). RESULTS Subjects were admitted to the ICU for a mean duration of 7.7 days (SD, 3.7 days) and required mechanical ventilation for a mean duration of 4.6 days (SD, 2.5 days). The mean FRI was 0.88 (SD, 0.13), indicating a 12% fall in P(I(max)), and was negatively correlated with MVD (r = -0.65; p = 0.007). No correlations were found between the FRI and FEV1, FVC, ICULOS, WD, or CCS. CONCLUSIONS Patients who had received mechanical ventilation for > 48 h have reduced inspiratory muscle endurance that worsens with the duration of mechanical ventilation and is present following successful weaning. These data suggest that patients needing prolonged mechanical ventilation are at risk of respiratory muscle fatigue and may benefit from respiratory muscle training.

Balance is impaired in people with chronic obstructive pulmonary disease

BACKGROUND It has recently been suggested that people with chronic obstructive pulmonary disease have an increased risk of falls. Although falls risk is multifactorial, impaired balance may contribute. The primary aim of this study was to compare balance between people with and without chronic obstructive pulmonary disease and the secondary aim was to determine if balance deteriorates when respiratory demand is increased by upper limb exercise. METHODS Twelve people with chronic obstructive pulmonary disease and 12 healthy control subjects participated in this study. Participants stood on a force plate to record centre of pressure displacement during a range of conditions that challenge balance. Lumbar spine and hip motion were measured with inclinometers. Balance trials were performed before and after participation in upper limb exercise that increased respiratory demand in those with chronic obstructive pulmonary disease. FINDINGS People with chronic obstructive pulmonary disease had increased mediolateral centre of pressure displacement and increased angular motion of the hip compared to healthy controls. Mediolateral centre of pressure displacement was further increased in people with chronic obstructive pulmonary disease following exercise, but unchanged in controls. Anteroposterior centre of pressure displacement did not differ between groups. INTERPRETATION People with chronic obstructive pulmonary disease have reduced control of balance in the mediolateral direction. This may contribute to an increased risk of falls in this population.

Standing with assistance of a tilt table in intensive care : A survey of Australian physiotherapy practice.

Although tilt tables are used by physiotherapists to reintroduce patients to the vertical position, no quantitative evidence is available regarding their use within intensive care units (ICUs) of Australian hospitals. The purpose of this study was to evaluate the use of tilt tables in physiotherapy management of patients in ICUs across Australia. Ninety-nine physiotherapists working in Australian public ICUs were contacted via mail and asked to complete a questionnaire regarding their use of tilt tables in practice. Reasons for the use of the tilt table, contraindications, commonly used adjuncts, monitoring, and outcome measures were also investigated. Eighty-six questionnaires were returned (87% response). The tilt table was used by 58 physiotherapists (67.4%). The most common reasons for inclusion of tilt table treatment were to: facilitate weight bearing (94.8% of those who tilt); prevent muscle contractures (86%); improve lower limb strength (81%); and increase arousal (70%). The tilt table was most frequently applied to patients with neurological conditions (63.8%) and during long-term ICU stay (43.1%). Techniques often combined with tilt table treatment included upper limb exercises (93.1%) and breathing exercises (86.2%). Standing with assistance of the tilt table is used by the majority of physiotherapists working in Australian ICUs. A moderate level of agreement is demonstrated by physiotherapists regarding indications to commence tilt table treatment and adjunct modalities combined with standing with assistance of the tilt table.

Changes in sitting posture induce multiplanar changes in chest wall shape and motion with breathing

This study examined the effect of sitting posture on regional chest wall shape in three dimensions, chest wall motion (measured with electromagnetic motion analysis system), and relative contributions of the ribcage and abdomen to tidal volume (%RC/V(t)) (measured with inductance plethysmography) in 7 healthy volunteers. In seven seated postures, increased dead space breathing automatically increased V(t) (to 1.5 V(t)) to match volume between conditions and study the effects of posture independent of volume changes. %RC/V(t) (p<0.05), chest wall shape (p<0.05) and motion during breathing differed between postures. Compared to a reference posture, movement at the 9th rib lateral diameter increased in the thoracolumbar extension posture (p<0.008). In slumped posture movement at the AP diameters at T1 and axilla increased (p<0.00001). Rotation postures decreased movement in the lateral diameter at the axilla (p<0.0007). The data show that single plane changes in sitting posture alter three-dimensional ribcage configuration and chest wall kinematics during breathing, while maintaining constant respiratory function.

Predictive Utility of the 6-Minute Walk Distance on Survival in Patients Awaiting Lung Transplantation

BACKGROUND The 6-minute walk distance (6MWD) is a widely used clinical indicator of exercise capacity. Although used as part of the assessment process in determining a candidates suitability for lung transplantation (LT), the literature describing the impact of the 6MWD in predicting survival on LT waiting lists is limited. This study aimed to determine the hazard function associated with the 6MWD, and its utility relative to other prognostic variables. METHODS A retrospective chart review was conducted on 163 patients who were listed for single or double LT, and either survived to transplant or died while on the waiting list. A Cox regression for survival analysis, stratified by diagnostic group, was conducted utilizing the 6MWD, demographic variables and measures of cardiopulmonary function. RESULTS The 6MWD proved to be the only significant covariate in the Cox regression for survival analysis (p < 0.001), with all other variables eliminated as non-significant. Furthermore, there was a protective effect for each unit increase in the 6MWD [Exp (B) = 0.994, 95% confidence interval 0.990 to 0.997]. CONCLUSIONS This research demonstrates that the 6MWD is useful for stratifying patients on the LT waiting list by identifying those patients with a significantly higher risk of mortality.

Static balance is affected following an exercise task in chronic obstructive pulmonary disease.

PURPOSE To investigate balance following a submaximal exercise task (6-minute walk test [6MWT]) in patients with chronic obstructive pulmonary disease (COPD). METHODS A consecutive sample of 19 patients with COPD from an institutional pulmonary rehabilitation program served as participants. The following measures were recorded before and following a 6MWT: (1) timed-up and go (TUG) test, (2) step-up test, and (3) quiet standing for 30 seconds with eyes open and closed in a narrow and semi-tandem stance. Displacement of the body at the level of the waist was recorded using a swaymeter. Data were analyzed using a linear mixed model. RESULTS In the semi-tandem stance with eyes closed post-6MWT, increases in total sway (165.9 mm vs 240.0 mm, P = .043) and mediolateral sway (45.8 mm vs 66.6 mm, P = .011) were found in comparison with pre-6MWT measures. The exercise task did not affect the TUG test performance (8.3 seconds vs 9.0 seconds, P = .213), number of steps completed during the step-up test (10 vs 10, P = .233), or sway during the semi-tandem stance with eyes open; narrow base, eyes open or closed (P > .05). Conclusions A submaximal exercise task in patients with COPD affects balance during static standing tasks in the absence of visual input. This may have implications for functional performance following exercise in patients with chronic respiratory disease.

Ventilatory changes following head-up tilt and standing in healthy subjects

Passive tilting increases ventilation in healthy subjects; however, controversy surrounds the proposed mechanism. This study is aimed to evaluate the possible mechanism for changes to ventilation following passive head-up tilt (HUT) and active standing by comparison of a range of ventilatory, metabolic and mechanical parameters. Ventilatory parameters (VT, VE, VE/VO2, VE/VCO2, f and PetCO2), functional residual capacity (FRC), respiratory mechanics with impulse oscillometry; oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured in 20 healthy male subjects whilst supine, following HUT to 70° and unsupported standing. Data were analysed using a linear mixed model. HUT to 70° from supine increased minute ventilation (VE) (P<0.001), tidal volume (VT) (P=0.001), ventilatory equivalent for O2 (VE/VO2) (P=0.020) and the ventilatory equivalent for CO2 (VE/VCO2) (P<0.001) with no change in f (P=0.488). HUT also increased FRC (P<0.001) and respiratory system reactance (X5Hz) (P<0.001) with reduced respiratory system resistance (R5Hz) (P=0.004) and end-tidal carbon dioxide (PetCO2) (P<0.001) compared to supine. Standing increased VE (P<0.001), VT (P<0.001) and VE/VCO2 (P=0.020) with no change in respiratory rate (f) (P=0.065), VE/VO2 (P=0.543). Similar changes in FRC (P<0.001), R5Hz (P=0.013), X5Hz (P<0.001) and PetCO2 (P<0.001) compared to HUT were found. In contrast to HUT, standing increased VO2 (P=0.002) and VCO2 (P=0.048). The greater increase in VE in standing compared to HUT appears to be related to increased VO2 and VCO2 associated with increased muscle activity in the unsupported standing position. This has implications for exercise prescription and rehabilitation of critically ill patients who have reduced cardiovascular and respiratory reserve.

Senior physiotherapy students as standardised patients for junior students enhances self-efficacy and satisfaction in both junior and senior students

BackgroundStandardised patients are used in medical education to expose students to clinical contexts and facilitate transition to clinical practice, and this approach is gaining momentum in physiotherapy programs. Expense and availability of trained standardised patients are factors limiting widespread adoption, and accessing clinical visits with real patients can be challenging. This study addressed these issues by engaging senior students as standardised patients for junior students. It evaluated how this approach impacted self-reported constructs of both the junior and senior students.MethodsLearning activities for undergraduate physiotherapy students were developed in five courses (Neurology, Cardiorespiratory and three Musculoskeletal courses) so that junior students (Year 2 and 3) could develop skills and confidence in patient interview, physical examination and patient management through their interaction with standardised patients played by senior students (Year 4). Surveys were administered before and after the interactions to record junior students’ self-reported confidence, communication, preparedness for clinic, and insight into their abilities; and senior students’ confidence and insight into what it is like to be a patient. Satisfaction regarding this learning approach was surveyed in both the junior and senior students.ResultsA total of 253 students completed the surveys (mean 92.5% response rate). Across all courses, junior students reported a significant (all P < 0.037) improvement following the standardised patient interaction in their: preparedness for clinic, communication with clients, confidence with practical skills, and understanding of their strengths and weaknesses in relation to the learning activities. Senior students demonstrated a significant improvement in their confidence in providing feedback and insight into their own learning (P < 0.001). All students reported high satisfaction with this learning experience (mean score 8.5/10).ConclusionThis new approach to peer-assisted learning using senior students as standardised patients resulted in positive experiences for both junior and senior students across a variety of physiotherapy areas, activities, and stages within a physiotherapy program. These findings support the engagement of senior students as standardised patients to enhance learning within physiotherapy programs, and may have application across other disciplines to address challenges associated with accessing real patients via clinical visits or utilising actors as standardised patients.

Metabolic disease and participant age are independent predictors of response to pulmonary rehabilitation.

PURPOSE: The study aims were (1) to determine whether baseline measures—including the Body Mass Index, Airflow Obstruction, Dyspnea, and Exercise Capacity (BODE) index; Age, Dyspnea, and Airflow Obstruction (ADO) index; physical activity; comorbidities (cardiac, metabolic, or musculoskeletal disease); and the number of hospitalizations over the previous 12 months—can predict responders in 6-minute walk distance (6MWD) following pulmonary rehabilitation (PR) and (2) to determine whether different methods in defining improvement in 6MWD affected identifying responders to PR. METHODS: All participants with chronic obstructive pulmonary disease who attended PR at our institution between 2004 and 2009 were evaluated. A participant was classified as a responder with improvement in 6MWD (≥25 m or ≥2 SD of this dataset coefficient of repeatability). RESULTS: A total of 203 participants (mean age, 68.2 ± 8.7 years; mean predicted forced expiratory volume in 1 second, 52.5 ± 22.4%) were analyzed. One hundred twenty participants (59.1%) had a comorbidity categorized as cardiac, metabolic, or musculoskeletal disease. The binary logistic regression models showed that younger participants (P ⩽ .015) and, when using the coefficient of repeatability method (≥60.9 m), participants with metabolic disease (P = .040) were the only independent predictors of response. No other measure, including participant BODE or ADO index scores, contributed to either model. CONCLUSION: Identifying responders in exercise capacity following PR remains difficult, with only age and participants with metabolic disease identified as independent predictors.

Ventilatory effects of neurophysiological facilitation and passive movement in patients with neurological injury.

Thirteen intubated, high dependency patients with neurological injuries were studied in order to investigate the short term respiratory effects of neurophysiological facilitation and passive movement on tidal volume (VT), minute ventilation (VE), respiratory rate (VR) and oxygen saturation (SpO2). The subjects were studied under four conditions: no intervention (control) and during periods of neurophysiological facilitation, passive movement and sensory stimulation. All periods were standardised to three minutes duration and all parameters were recorded before and after each intervention. Neurophysiological facilitation produced significant increases (p < 0.01) in VE and SpO2 (p < 0.05) when compared with control values, with an overall mean increase in VE of 14.6%. Similarly, passive movement increased VE (p < 0.01) by an average of 9.8% and also increased SpO2 (p < 0.01). In contrast, sensory stimulation produced significant increases (p < 0.01) in SpO2 with control levels, with no significant change in VT or VE. There was no significant difference in VR with all treatments. This study provides preliminary evidence of improved short term ventilatory function following neurophysiological facilitation, independent of generalised sensory stimulation, which has not been previously examined in the literature, supporting its use in the management of high dependency neurological patients.