Background: Reference values derived from existing diaphragm ultrasound protocols are inconsistent, and the association between sonographic measures of diaphragm function and volitional tests of respiratory muscle strength is still ambiguous. Objective: To propose a standardized and comprehensive protocol for diaphragm ultrasound in order to determine lower limits of normal (LLN) for both diaphragm excursion and thickness in healthy subjects and to explore the association between volitional tests of respiratory muscle strength and diaphragm ultrasound parameters. Methods: Seventy healthy adult subjects (25 men, 45 women; age 34 ± 13 years) underwent spirometric lung function testing, determination of maximal inspiratory and expiratory pressure along with ultrasound evaluation of diaphragm excursion and thickness during tidal breathing, deep breathing, and maximum voluntary sniff. Excursion data were collected for amplitude and velocity of diaphragm displacement. Diaphragm thickness was measured in the zone of apposition at total lung capacity (TLC) and functional residual capacity (FRC). All participants underwent invasive measurement of transdiaphragmatic pressure (Pdi) during different voluntary breathing maneuvers. Results: Ultrasound data were successfully obtained in all participants (procedure duration 12 ± 3 min). LLNs (defined as the 5th percentile) for diaphragm excursion were as follows: (a) during tidal breathing: 1.2 cm (males; M) and 1.2 cm (females; F) for amplitude, and 0.8 cm/s (M) and 0.8 cm/s (F) for velocity, (b) during maximum voluntary sniff: 2.0 cm (M) and 1.5 cm (F) for amplitude, and 6.7 (M) cm/s and 5.2 cm/s (F) for velocity, and (c) at TLC: 7.9 cm (M) and 6.4 cm (F) for amplitude. LLN for diaphragm thickness was 0.17 cm (M) and 0.15 cm (F) at FRC, and 0.46 Spiesshoefer et al. cm (M) and 0.35 cm (F) at TLC. Values for males were consistently higher than for females, independent of age. LLN for diaphragmatic thickening ratio was 2.2 with no difference between genders. LLN for invasively measured Pdi during different breathing maneuvers are presented. Voluntary Pdi showed only weak correlation with both diaphragm excursion velocity and amplitude during forced inspiration. Conclusions: Diaphragm ultrasound is an easy-to-perform and reproducible diagnostic tool for noninvasive assessment of diaphragm excursion and thickness. It supplements but does not replace respiratory muscle strength testing.

No abstract

No abstract

Introduction The purpose of this study was to comprehensively evaluate respiratory muscle function in adults with facioscapulohumeral muscular dystrophy (FSHD). Methods Fourteen patients with FSHD (9 men, 53 ± 16 years of age) and 14 matched controls underwent spirometry, diaphragm ultrasound, and measurement of twitch gastric and transdiaphragmatic pressures (twPgas and twPdi; n = 10) after magnetic stimulation of the lower thoracic nerve roots and the phrenic nerves. The latter was combined with recording of diaphragm compound muscle action potentials (CMAPs; n = 14). Results The following parameters were significantly lower in patients vs controls: forced vital capacity (FVC); maximum inspiratory and expiratory pressure; peak cough flow; diaphragm excursion amplitude; and thickening ratio on ultrasound, twPdi (11 ± 5 vs 20 ± 6 cmH2O) and twPgas (7 ± 3 vs 25 ± 20 cmH2O). Diaphragm CMAP showed no group differences. FVC correlated inversely with the clinical severity scale score (r = −0.63, P = .02). Discussion In FSHD, respiratory muscle weakness involves both the diaphragm and the expiratory abdominal muscles.

The clinical course of COVID-19 is very heterogeneous: Most infected individuals can be managed in an outpatient setting, but a substantial proportion of patients requires intensive care, resulting in a high rate of fatalities. Recently, an association between contact to small children and mild course of COVID-19 was reported. We performed an observational study to assess the impact of previous infections with seasonal coronaviruses on COVID-19 severity. 60 patients with confirmed COVID-19 infections were included (age 30 - 82 years; 52 males, 8 females): 19 inpatients with critical disease, 16 inpatients with severe or moderate disease and 25 outpatients (age and gender matched to inpatients). Patients with critical disease had significantly lower levels of HCoV OC43- (p=0.016) and HCoV HKU1-specific (p=0.023) antibodies at the first encounter compared to other COVID-19 patients. Our results indicate that previous infections with seasonal coronaviruses might protect against a severe course of disease. This finding should be validated in other settings and could contribute to identify persons at risk before an infection.

The clinical course of COVID-19 is very heterogeneous: Most infected individuals can be managed in an outpatient setting, but a substantial proportion of patients requires intensive care, resulting in a high rate of fatalities. We performed a biomarker study to assess the impact of prior infections with seasonal coronaviruses on COVID-19 severity. 60 patients with confirmed COVID-19 infections were included (age 30 - 82 years; 52 males, 8 females): 19 inpatients with critical disease, 16 inpatients with severe or moderate disease and 25 outpatients. Patients with critical disease had significantly lower levels of anti-HCoV OC43-NP (p = 0.016) and HCoV HKU1-NP (p = 0.023) antibodies at the first encounter compared to other COVID-19 patients. Our results indicate that prior infections with seasonal coronaviruses might protect against a severe course of disease.

Diaphragm weakness in Charcot‐Marie‐Tooth disease 1A (CMT1A) is usually associated with severe disease manifestation. This study comprehensively investigated phrenic nerve conductivity, inspiratory and expiratory muscle function in ambulatory CMT1A patients. Nineteen adults with CMT1A (13 females, 47 ± 12 years) underwent spiromanometry, diaphragm ultrasound, and magnetic stimulation of the phrenic nerves and the lower thoracic nerve roots, with recording of diaphragm compound muscle action potentials (dCMAP, n = 15), transdiaphragmatic and gastric pressures (twPdi and twPgas, n = 12). Diaphragm motor evoked potentials (dMEP, n = 15) were recorded following cortical magnetic stimulation. Patients had not been selected for respiratory complaints. Disease severity was assessed using the CMT Neuropathy Scale version 2 (CMT‐NSv2). Healthy control subjects were matched for age, sex, and body mass index. The following parameters were significantly lower in CMT1A patients than in controls (all P < .05): forced vital capacity (91 ± 16 vs 110 ± 15% predicted), maximum inspiratory pressure (68 ± 22 vs 88 ± 29 cmH2O), maximum expiratory pressure (91 ± 23 vs 123 ± 24 cmH2O), and peak cough flow (377 ± 135 vs 492 ± 130 L/min). In CMT1A patients, dMEP and dCMAP were delayed. Patients vs controls showed lower diaphragm excursion (5 ± 2 vs 8 ± 2 cm), diaphragm thickening ratio (DTR, 1.9 [1.6‐2.2] vs 2.5 [2.1‐3.1]), and twPdi (8 ± 6 vs 19 ± 7 cmH2O; all P < .05). DTR inversely correlated with the CMT‐NSv2 score (r = −.59, P = .02). There was no group difference in twPgas following abdominal muscle stimulation. Ambulatory CMT1A patients may show phrenic nerve involvement and reduced respiratory muscle strength. Respiratory muscle weakness can be attributed to diaphragm dysfunction alone. It relates to neurological impairment and likely reflects a disease continuum.

No abstract