Global tidal variations, regional distribution of ventilation, and the regional onset of filling determined by electrical impedance tomography: reproducibility.

The reproducibility of the regional distribution of ventilation and the timing of onset of regional filling as measured by electrical impedance tomography lacks evidence. This study investigated whether electrical impedance tomography measurements in healthy males were reproducible when electrodes were replaced between measurements. Part 1: Recordings of five volunteers lying supine were made using electrical impedance tomography and a pneumotachometer. Measurements were repeated at least three hours later. Skin marking ensured accurate replacement of electrodes. No stabilisation period was allowed. Part 2: Electrical impedance tomography recordings of ten volunteers; a 15 minute stabilisation period, extra skin markings, and time-averaging were incorporated to improve the reproducibility. Reproducibility was determined using the Bland-Altman method. To judge the transferability of the limits of agreement, a Pearson correlation was used for electrical impedance tomography tidal variation and tidal volume. Tidal variation was judged to be reproducible due to the significant correlation between tidal variation and tidal volume (r2 = 0.93). The ventilation distribution was not reproducible. A stabilisation period, extra skin markings and time-averaging did not improve the outcome. The timing of regional onset of filling was reproducible and could prove clinically valuable. The reproducibility of the tidal variation indicates that non-reproducibility of the ventilation distribution was probably a biological difference and not measurement error. Other causes of variability such as electrode placement variability or lack of stabilisation when accounted for did not improve the reproducibility of the ventilation distribution.

Does objective measurement of tracheal tube cuff pressures minimise adverse effects and maintain accurate cuff pressures? A systematic review and meta-analysis.

Correct inflation pressures of the tracheal cuff are recommended to ensure adequate ventilation and prevent aspiration and adverse events. However there are conflicting views on which measurement to employ. The aim of this review was to examine whether adjustment of cuff pressure guided by objective measurement, compared with subjective measurement or observation of the pressure value alone, was able to prevent patient-related adverse effects and maintain accurate cuff pressures. A search of PubMed, Web of Science, Embase, CINAHL and ScienceDirect was conducted using keywords 'cuff pressure' and 'measure*' and related synonyms. Included studies were randomised or pseudo-randomised controlled trials investigating mechanically ventilated patients both in the intensive care unit and during surgery. Outcomes included adverse effects and the comparison of pressure measurements. Pooled analyses were performed to calculate risk ratios, effect sizes and 95% confidence intervals. Meta-analysis found preliminary evidence that adjustment of cuff pressure guided by objective measurement as compared with subjective measurement or observation of the pressure value alone, has benefit in preventing adverse effects. These included cough at two hours (odds ratio [OR] 0.42, confidence interval [CI] 0.23 to 0.79, P=0.007), hoarseness at 24 hours (OR 0.49, CI 0.31 to 0.76, P <0.002), sore throat (OR 0.73, CI 0.54 to 0.97, P <0.03), lesions of the trachea and incidences of silent aspiration (P=0.001), as well as maintaining accurate cuff pressures (Hedges' g 1.61, CI 2.69 to 0.53, P=0.003). Subjective measurement to guide adjustment or observation of the pressure value alone may lead to patient-related adverse effects and inaccuracies. It is recommended that an objective form of measurement be used.

The time taken for the regional distribution of ventilation to stabilise: an investigation using electrical impedance tomography.

Electrical impedance tomography is a novel technology capable of quantifying ventilation distribution in the lung in real time during various therapeutic manoeuvres. The technique requires changes to the patient's position to place the electrical impedance tomography electrodes circumferentially around the thorax. The impact of these position changes on the time taken to stabilise the regional distribution of ventilation determined by electrical impedance tomography is unknown. This study aimed to determine the time taken for the regional distribution of ventilation determined by electrical impedance tomography to stabilise after changing position. Eight healthy, male volunteers were connected to electrical impedance tomography and a pneumotachometer. After 30 minutes stabilisation supine, participants were moved into 60 degrees Fowler's position and then returned to supine. Thirty minutes was spent in each position. Concurrent readings of ventilation distribution and tidal volumes were taken every five minutes. A mixed regression model with a random intercept was used to compare the positions and changes over time. The anterior-posterior distribution stabilised after ten minutes in Fowler's position and ten minutes after returning to supine. Left-right stabilisation was achieved after 15 minutes in Fowler's position and supine. A minimum of 15 minutes of stabilisation should be allowed for spontaneously breathing individuals when assessing ventilation distribution. This time allows stabilisation to occur in the anterior-posterior direction as well as the left-right direction.

The clinical role of glutamine supplementation in patients with multiple trauma: a narrative review.

Glutamine is considered an essential amino acid during stress and critical illness. Parenteral glutamine supplementation in critically ill patients has been shown to improve survival rate and minimise infectious complications, costs and hospital length-of-stay. However, glutamine supplementation in patients receiving enteral nutrition and the best method of administration are still controversial. The purpose of this article is to provide a narrative review of the current evidence and trials of enteral and parenteral glutamine supplementation in multiple trauma patients. A search in PubMed and EMBASE was conducted and relevant papers that investigated the effect of enteral or parenteral glutamine supplementation in patients with multiple trauma were reviewed. Although recent nutritional guidelines recommend that glutamine supplementation should be considered in these patients, further well-designed trials are required to provide a confirmed conclusion. Due to the inconclusive results of enteral glutamine supplementation trials in patients receiving enteral nutrition, future trials should focus on intravenous glutamine supplementation in patients requiring enteral nutrition and on major clinical outcome measures (e.g. mortality rate, infectious complications).

Respiratory dysfunction in ventilated patients: can inspiratory muscle training help?

Respiratory muscle dysfunction is associated with prolonged and difficult weaning from mechanical ventilation. This dysfunction in ventilator-dependent patients is multifactorial: there is evidence that inspiratory muscle weakness is partially explained by disuse atrophy secondary to ventilation, and positive end-expiratory pressure can further reduce muscle strength by negatively shifting the length-tension curve of the diaphragm. Polyneuropathy is also likely to contribute to apparent muscle weakness in critically ill patients, and nutritional and pharmaceutical effects may further compound muscle weakness. Moreover, psychological influences, including anxiety, may contribute to difficulty in weaning. There is recent evidence that inspiratory muscle training is safe and feasible in selected ventilator-dependent patients, and that this training can reduce the weaning period and improve overall weaning success rates. Extrapolating from evidence in sports medicine, as well as the known effects of inspiratory muscle training in chronic lung disease, a theoretical model is proposed to describe how inspiratory muscle training enhances weaning and recovery from mechanical ventilation. Possible mechanisms include increased protein synthesis (both Type 1 and Type 2 muscle fibres), enhanced limb perfusion via dampening of a sympathetically-mediated metaboreflex, reduced lactate levels and modulation of the perception of exertion, resulting in less dyspnoea and enhanced exercise capacity.

Fatigue, muscle strength and vitamin D status in women with systemic lupus erythematosus compared with healthy controls.

Recent studies have demonstrated an inverse relationship between vitamin D levels and fatigue in systemic lupus erythematosus (SLE). The aims of this study were to evaluate proximal muscle strength, fatigue and vitamin D levels in women with SLE compared with healthy controls and to investigate relationships between these factors in a cohort of women with SLE. Forty-five women (24 SLE, 21 healthy controls) participated. Primary outcome measures were the fatigue severity scale (FSS), isometric muscle strength of dominant limbs using hand held dynamometry, two functional tests--the 30-second chair stand test and the 1-kg arm lift test, with vitamin D status measured using 25(OH)D. Overall 25(OH)D levels were 68.4 (22.4) nmol/L with no difference between SLE and control groups. There was a statistically and clinically significant difference in fatigue, 1-kg arm lift, 30-second sit to stand, knee extension, hip flexion, hip abduction, shoulder flexion and grip strength in the SLE group compared with the control group (p < 0.05). In the SLE group FSS was moderately correlated with both functional measures (1-kg arm lift r = -0.42, 30-second chair stand r = -0.44, p < 0.05). However, no statistically significant correlation between dynamometry measures and fatigue was evident. There was no association between fatigue and 25(OH)D level (r = -0.12). In summary, women with SLE were weaker and demonstrated reduced physical function and higher fatigue levels than healthy controls. Fatigue was related to physical function but not vitamin D status or maximal isometric strength in vitamin D replete individuals with SLE.

Determining authorship in multicenter trials: a systematic review.

The practical and ethical issues in determining authorship in multicenter trials raise significant and unique challenges. This systematic review examines methods of assigning authorship in multicenter clinical trials. A literature search (October 2009) was conducted to identify articles with the terms 'authorship' and 'clinical trial,' 'multicenter' or 'multicentre.' Abstracts were reviewed for potential relevance and the complete manuscript was obtained where indicated. Additional articles were identified by a review of the reference list from sourced articles. Methods for determining authorship were reviewed in terms of practicality, fairness and the time course for decision-making. Eight methods for determining authorship were identified: four used a scoring system, two articles contained guidelines with reference to scoring systems and two articles outlined general guidelines. All methods attempted to provide a fair and practical approach and appeared to achieve this to varying degrees. No one method was applicable across all multicenter trials. The authors propose a guide for determining authorship based on the methods identified and the number of collaborators and anticipated publications. For smaller collaborative groups (e.g. <10 persons), byline inclusion of all authors based on relative contributions is recommended. For larger collaborations (e.g. ≥ 10 persons), authorship guidelines should be explicit from the outset of the trial with consideration of relevant scoring systems.

Test-retest reliability of hand-held dynamometry and functional tests in systemic lupus erythematosus.

The aim of this study was to evaluate the test-retest reliability and determine the degree of measurement error of tests of isometric muscle strength and upper and lower limb function in women with systemic lupus erythematosus (SLE). Twelve women with SLE (age 39.8 ± 10 years) were assessed on two occasions separated by a 7-10-day interval. Strength of six muscle groups was measured using a hand-held dynamometer; function was measured by the 30-s sit to stand test and the 30-s 1 kg arm lift. Relative reliability was estimated using the intraclass correlation coefficient (ICC), model 2,1 (ICC2,1). Absolute reliability was estimated using standard error measurement and the minimal detectable difference was calculated. All ICCs were greater than 0.87. Muscle strength would need to increase by between 18% and 39% in women with SLE to be 95% confident of detecting real changes. The functional tests demonstrated a systematic bias between trials. This study demonstrates that hand-held dynamometry in SLE can be performed with excellent reliability. Further work needs to be completed to determine the number of trials necessary for both the 30-s sit to stand and 30-s 1 kg arm lift to decrease the systematic bias.

Effect of vitamin D supplementation on muscle strength: a systematic review and meta-analysis.

UNLABELLED: This systematic review demonstrates that vitamin D supplementation does not have a significant effect on muscle strength in vitamin D replete adults. However, a limited number of studies demonstrate an increase in proximal muscle strength in adults with vitamin D deficiency. INTRODUCTION: The purpose of this study is to systematically review the evidence on the effect of vitamin D supplementation on muscle strength in adults. METHODS: A comprehensive systematic database search was performed. Inclusion criteria included randomised controlled trials (RCTs) involving adult human participants. All forms and doses of vitamin D supplementation with or without calcium supplementation were included compared with placebo or standard care. Outcome measures included evaluation of strength. Outcomes were compared by calculating standardised mean difference (SMD) and 95% confidence intervals. RESULTS: Of 52 identified studies, 17 RCTs involving 5,072 participants met the inclusion criteria. Meta-analysis showed no significant effect of vitamin D supplementation on grip strength (SMD -0.02, 95%CI -0.15,0.11) or proximal lower limb strength (SMD 0.1, 95%CI -0.01,0.22) in adults with 25(OH)D levels > 25 nmol/L. Pooled data from two studies in vitamin D deficient participants (25(OH)D <25 nmol/L) demonstrated a large effect of vitamin D supplementation on hip muscle strength (SMD 3.52, 95%CI 2.18, 4.85). CONCLUSION: Based on studies included in this systematic review, vitamin D supplementation does not have a significant effect on muscle strength in adults with baseline 25(OH)D >25 nmol/L. However, a limited number of studies demonstrate an increase in proximal muscle strength in adults with vitamin D deficiency.

Unplanned early readmission to the intensive care unit: a case-control study of patient, intensive care and ward-related factors.

The purpose of this study was to identify patient, intensive care and ward-based risk factors for early, unplanned readmission to the intensive care unit. A five-year retrospective case-control study at a tertiary referral teaching hospital of 205 cases readmitted within 72 hours of intensive care unit discharge and 205 controls matched for admission diagnosis and severity of illness was conducted. The rate of unplanned readmissions was 3.1% and cases had significantly higher overall mortality than control patients (odds ratio [OR] 4.7, 95% confidence interval [CI] 2.1 to 10.7). New onset respiratory compromise and sepsis were the most common cause of readmission. Independent risk factors for readmission were chronic respiratory disease (OR 3.7, 95% CI 1.2 to 12, P = 0.029), pre-existing anxiety/depression (OR 3.3, 95% CI 1.7 to 6.6, P < 0.001), international normalised ratio >1.3 (OR 2.3, 95% CI 1.1 to 4.9, P = 0.024), immobility (OR 2.3, 95% CI 1.4 to 3.6, P = 0.001), nasogastric nutrition (OR 2.0, 95% CI 1.0 to 4.0, P = 0.041), a white cell count > 15 x 10(9)/l (OR 2.0, 95% CI 1.2 to 3.4, P = 0.012) and non-weekend intensive care unit discharge (OR 1.9, 95% CI 1.1 to 3.5, P = 0.029). Physiological derangement on the ward (OR 26, 95% CI 8.0 to 81, P < 0.001) strongly predicted readmission, although only 20% of patients meeting medical emergency team criteria had a medical emergency team call made. Risk of readmission is associated with both patient and intensive care factors. Physiological derangement on the ward predicts intensive care unit readmission, however, clinical response to this appears suboptimal.

Abdominal binder use in people with spinal cord injuries: a systematic review and meta-analysis.

STUDY DESIGN: Systematic review and meta-analysis. OBJECTIVES: To review the evidence for the use of an abdominal binder on breathing, speech and cardiovascular function in people who have suffered a spinal cord injury (SCI). SETTING: Brisbane, Australia. METHODS: A search of multiple databases (Medline, Cinahl, Cochrane, Embase, PEDro) was undertaken accompanied by the reference list evaluation of each relevant publication identified. Methodological quality of studies identified was assessed using the PEDro scale. The size of effect of an abdominal binder on outcomes was also calculated where sufficient data were reported. Further descriptive analysis was performed. RESULTS: Eleven studies met the review inclusion criteria and employed either crossover or within subject designs. Comparison of studies involving elastic and non-elastic binders was performed. A PEDro mean score of 4.3 out of 8 (range: 3-6) was found. Meta-analysis indicated that the use of abdominal binders improved vital capacity (VC) by (weighted mean difference (95% confidence interval (CI)) 0.32 (0.09, 0.55) litres, decreased functional residual capacity (FRC) by 0.41 (0.14, 0.67) litres, but did not significantly influence total lung capacity (TLC). CONCLUSIONS: This review found some evidence that the use of an abdominal binder improves VC, but decreases FRC when assuming the sitting or tilted position in people who have suffered SCI. Overall, the quality of the studies was poor. Available evidence is not yet sufficient to either support or discourage the use of an abdominal binder in this patient population. Further studies utilizing more methodologically rigorous designs are required.

Qualitative outcomes of progressive resistance exercise for people with COPD.

The outcomes of quantitative investigations examining the effectiveness of exercise interventions for people with COPD are limited by the small number of measurement tools that can be included. In contrast, qualitative inquiry allows broader exploration of the perceived outcomes of an intervention. The purpose of this investigation is to explore the qualitative outcomes of a progressive resistance exercise (PRE) program for people with COPD. People with COPD, enrolled in a randomized controlled trial of PRE, were invited to participate in two semi-structured interviews conducted at the end (12 weeks) and 12 weeks after the training intervention (24 weeks). Interviews were audiotaped, transcribed and then coded independently by two researchers. Themes relating to training outcomes were then developed and described. Twenty-two participants were interviewed at 12 weeks, and 19 participants at 24 weeks. After PRE, participants reported a range of physical gains, particularly with regard to improved strength and reduced breathlessness during daily activities. Improved control and confidence during activities of daily living were important psychological benefits perceived by people with COPD, as was the social support experienced during group training sessions. At 24 weeks, confidence persisted despite a perceived plateau or dissipation of physical gains. People with COPD reported physical, psychological and social benefits after PRE, which had a positive effect on activity performance. Although the perceived physical benefits of training were not prominent at 24 weeks, feelings of increased confidence and control persisted.

Is there evidence to support the use of lateral positioning in intensive care? A systematic review.

A systematic review of randomised clinical trials was conducted to investigate the efficacy and safety of use of the lateral position in the management of ventilated intensive care patients. One review article and 11 empiric studies, which were mostly of low methodological quality, met the eligibility criteria. Large individual variations in PaO2 response to lateral positioning were demonstrated. Greatest improvement in PaO2 occurred in patients with unilateralpulmonary infiltrates positioned with the bad lung up versus bad lung down (average difference = 33.6 mmHg (range 0-58), effect size 1.13 (95% CI: 0.44, 1.19, P = 0.001)) or supine (average difference=27 mmHg (range 5-42), effect size 0.58 (95% CI: 0.11, 1.06, P = 0.017)). This effect appeared to be most prominent in patients with widespread, unilateral infiltrates. Lung compliance was not affected by lateral positioning. Haemodynamic compromise was evident with lateral positioning of greater than 60 degrees to the right side in patients requiring vasopressors and/or with right ventricular dysfunction; or with lateral positioning in postoperative coronary artery bypass graft patients. No studies were found that had investigated the effect of routine applications of the lateral positioning to improve, prevent or treat pneumonia, decrease mortality or influence other long-term outcomes. The results of this review demonstrate the limited evidence available to support the use of lateral positioning in the intensive care environment. More data reporting the long-term effects of lateral position on long-term outcomes would aid clinical decision making and may improve the application of patient positioning in critical care environments.

Hemodynamic and ventilatory effects of manual respiratory physiotherapy techniques of chest clapping, vibration, and shaking in an animal model.

Chest clapping, vibration, and shaking were studied in 10 physiotherapists who applied these techniques on an anesthetized animal model. Hemodynamic variables (such as heart rate, blood pressure, pulmonary artery pressure, and right atrial pressure) were measured during the application of these techniques to verify claims of adverse events. In addition, expired tidal volume and peak expiratory flow rate were measured to ascertain effects of these techniques. Physiotherapists in this study applied chest clapping at a rate of 6.2 +/- 0.9 Hz, vibration at 10.5 +/- 2.3 Hz, and shaking at 6.2 +/- 2.3 Hz. With the use of these rates, esophageal pressure swings of 8.8 +/- 5.0, 0.7 +/- 0.3, and 1.4 +/- 0.7 mmHg resulted from clapping, vibration, and shaking respectively. Variability in rates and "forces" generated by these techniques was <20% in average coefficients of variation. In addition, clinical experience accounted for 76% of the variance in vibration rate (P = 0.001). Cardiopulmonary physiotherapy experience and layers of towel used explained approximately 79% of the variance in clapping force (P = 0.004), whereas age and clinical experience explained >80% of variance in shaking force (P = 0.003). Application of these techniques by physiotherapists was found to have no significant effects on hemodynamic and most ventilatory variables in this study. From this study, we conclude that chest clapping, vibration, and shaking 1). can be consistently performed by physiotherapists; 2). are significantly related to physiotherapists' characteristics, particularly clinical experience; and 3). caused no significant hemodynamic effects.