ABSTRACT

Background and objective: Evaluation of diaphragm function in Amyotrophic Lateral Sclerosis (ALS) is critical in determining when to commence non-invasive mechanical ventilation (NIV). Currently, forced vital capacity (FVC) and sniff nasal inspiratory pressure (SNIP) are volitional measures for this evaluation, but require collaboration and are poorly specific. The primary aim of this study was to assess whether diaphragmatic thickness measured by ultrasound (US) correlates with lung function impairment in ALS patients. The secondary aim was then to compare US diaphragm thickness index (ΔTdi) with a new parameter (ΔTmax index). Methods: 41 patients with ALS and 30 healthy subjects were enrolled in the study. All subjects underwent spirometry, SNIP and diaphragm US evaluation, while arterial blood gases were measured in some patients only. US assessed diaphragm thickness (Tdi) at tidal volume (Vt) or total lung capacity (TLC), and their ratio (ΔTmax) were recorded. Changes (Δ) in Tdi indices during tidal volume (ΔTdiVt) and maximal inspiration (ΔTdiTLC) were also assessed. Results: ΔTdiTLC (p <0.001) and ΔTmax (p = 0.007), but not ΔTdiVt, differed between patients and controls. Significant correlation (p < 0.05) was found between ΔTdiTLC, ΔTmax and FVC. The ROC curve analysis for comparison of individual testing showed better accuracy with Δtmax than with ΔtdiTLC for FVC (AUC 0.76 and 0.27) and SNIP (AUC 0.71 and 0.25). Conclusion: Diaphragm thickness assessed by ultrasound significantly correlates with global respiratory alterations in patients with ALS. ΔTmax represents a new US index of early diaphragmatic dysfunction, better related with the routinely performed lung function tests.

These preliminary data suggest that temporary positive expiratory pressure improves lung volumes and speeds up the improvement of bronchial encumbrance in patients with lung diseases and hypersecretion.

BACKGROUND: Oxygen desaturation during walking can have important consequence on prognosis of COPD patients. However, a standard 6-min walk test (6MWT), useful in detecting desaturation in COPD patients, can be difficult to execute in some settings of COPD management, as in the community healthcare service. We evaluated a new scoring system for the risk of oxygen desaturation during walking in COPD patients: the walking desaturation score. METHODS: We collected data from symptomatic COPD in-patients admitted for rehabilitation (derivation cohort) and out-patients referred to the local community health service (validation cohort). S pO 2 was monitored during 6MWT, and the subjects were classified as walking desaturators or non-desaturators. By a regression analysis model we assigned a weighted score proportional to the measured percentage of explained variance for each variable. Risk estimates were computed as odds ratios. A receiver operating characteristic curve analysis and a Hosmer-Lemeshow goodness-of-fit test were then performed to measure discrimination and calibration of walking desaturation score. RESULTS: Baseline characteristics in the derivation cohort (n ‫؍‬ 435, 74% of whom were walking desaturators) and the validation cohort (n ‫؍‬ 238, 37% of whom were walking desaturators) were different. Resting arterial oxygen saturation measured from an arterial blood sample, P aO 2 , and percent-of-predicted FEV 1 were the variables that predicted walking desaturation. The proportion of walking desaturators (and odds ratio estimate) gradually increased according to walking desaturation score (range 0 -6) and associated categories of desaturation risk (total walking desaturation score: low 0 or 1, high 2-3, very high 4 -6) (chi-square P < .001). There was considerable predictive discrimination (area under the curve 0.90, 95% CI 0.86 -0.93, P < .001), and calibration (Hosmer-Lemeshow chi-square 1.31, P ‫؍‬ .86) values have been shown. CONCLUSIONS: Walking desaturation score accurately predicts and classifies the risk of walking desaturation in COPD patients. ClinicalTrials.gov Number NCT01303913.