Maximum inspiratory pressure, a surrogate parameter for the assessment of ICU-acquired weakness

<p>Abstract</p> <p>Background</p> <p>Physical examination has been advocated as a primary determinant of ICU-acquired weakness (ICU-AW). The purpose of the study is to investigate ICU-AW development by using Maximum Inspiratory Pressure (MIP) as a surrogate parameter of the standardized method to evaluate patients' peripheral muscle strength.</p> <p>Methods</p> <p>Seventy-four patients were recruited in the study and prospectively evaluated in a multidisciplinary university ICU towards the appearance of ICU-AW. APACHE II admission score was 16 ± 6 and ICU stay 26 ± 18 days. ICU-AW was diagnosed with the Medical Research Council (MRC) scale for the clinical evaluation of muscle strength. MIP was measured using the unidirectional valve method, independently of the patients' ability to cooperate.</p> <p>Results</p> <p>A significant correlation was found between MIP and MRC (r = 0.68, p < 0.001). Patients that developed ICU-AW (MRC<48) had a longer weaning period compared to non ICU-AW patients (12 ± 14 versus 2 ± 3 days, p < 0.01). A cut-off point of 36 cmH₂O for MIP was defined by ROC curve analysis for ICU-AW diagnosis (88% sensitivity,76% specificity). Patients with MIP below the cut-off point of 36 cmH₂O had a significant greater weaning period (10 ± 14 versus 3 ± 3 days, p = 0.004) also shown by Kaplan-Meier analysis (log-rank:8.2;p = 0.004).</p> <p>Conclusions</p> <p>MIP estimated using the unidirectional valve method may be a potential surrogate parameter for the assessment of muscle strength compromise, useful for the early detection of ICU-AW.</p

Exercise Training Enhances Angiogenesis-Related Gene Responses in Skeletal Muscle of Patients with Chronic Heart Failure

Peripheral myopathy consists of a hallmark of heart failure (HF). Exercise enhanced skeletal muscle angiogenesis, and thus, it can be further beneficial towards the HF-induced myopathy. However, there is limited evidence regarding the exercise type that elicits optimum angiogenic responses of skeletal muscle in HF patients. This study aimed to (a) compare the effects of a high-intensity-interval-training (HIIT) or combined HIIT with strength training (COM) exercise protocol on the expression of angiogenesis-related factors in skeletal muscle of HF patients, and (b) examine the potential associations between the expression of those genes and capillarization in the trained muscles. Thirteen male patients with chronic HF (age: 51 +/- 13 y; BMI: 27 +/- 4 kg/m(2)) were randomly assigned to a 3-month exercise program that consisted of either HIIT (N = 6) or COM training (N = 7). Vastus lateralis muscle biopsies were performed pre- and post-training. RT-PCR was used to quantify the fold changes in mRNA expression of vascular endothelial growth factor (VEGF), vascular endothelial growth factor receptor 2 (VEGFR-2), hypoxia-inducible factor 1 alpha (HIF-1 alpha), angiopoietin 1 (Ang-1), angiopoietin 2 (Ang-2), angiopoietin receptor (Tie2), and matrix metallopeptidase 9 (MMP-9), and immunohistochemistry to assess capillarization in skeletal muscle post-training. There was an overall increase in the expression levels of VEGF, VEGFR-2, HIF-1 alpha, Ang2, and MMP9 post-training, while these changes were not different among groups. Changes in capillary-to-fibre ratio were found to be strongly associated with Tie2 and HIF-1 alpha expression. This was the first study demonstrating that both HIIT and combined HIIT with strength training enhanced similarly the expression profile of angiogenic factors in skeletal muscle of HF patients, possibly driving the angiogenic program in the trained muscles, although those gene expression increases were found to be only partially related with muscle capillarization