Assessing Diaphragm Function in Chest Wall and Neuromuscular Diseases

Chest Dynamic MRI as Early Biomarker of Respiratory Impairment in Amyotrophic Lateral Sclerosis Patients: A Pilot Study

Background: Amyotrophic lateral sclerosis (ALS) is a neuromuscular progressive disorder characterized by limb and bulbar muscle wasting and weakness. A total of 30% of patients present a bulbar onset, while 70% have a spinal outbreak. Respiratory involvement represents one of the worst prognostic factors, and its early identification is fundamental for the early starting of non-invasive ventilation and for the stratification of patients. Due to the lack of biomarkers of early respiratory impairment, we aimed to evaluate the role of chest dynamic MRI in ALS patients. Methods: We enrolled 15 ALS patients and 11 healthy controls. We assessed the revised ALS functional rating scale, spirometry, and chest dynamic MRI. Data were analyzed by using the Mann-Whitney U test and Cox regression analysis. Results: We observed a statistically significant difference in both respiratory parameters and pulmonary measurements at MRI between ALS patients and healthy controls. Moreover, we found a close relationship between pulmonary measurements at MRI and respiratory parameters, which was statistically significant after multivariate analysis. A sub-group analysis including ALS patients without respiratory symptoms and with normal spirometry values revealed the superiority of chest dynamic MRI measurements in detecting signs of early respiratory impairment. Conclusions: Our data suggest the usefulness of chest dynamic MRI, a fast and economically affordable examination, in the evaluation of early respiratory impairment in ALS patients.

Diaphragm Ultrasonography: Reference Values and Influencing Factors for Thickness, Thickening Fraction, and Excursion in the Seated Position

INTRODUCTION

Measurements of diaphragm function by ultrasonography are affected by body position, but reference values in the seated position have not been established for an Asian population. This study aimed to determine reference values for diaphragm thickness, thickening fraction, and dome excursion by ultrasonography and to investigate the effects of sex, height, and body mass index.

METHODS

Diaphragm ultrasonography was performed on 109 seated Japanese volunteers with normal respiratory function who were enrolled between March 2022 and January 2023. Thickness, thickening fraction, and excursion were measured. Reference values and the measurement success rate were calculated. Multivariate analysis adjusted for sex, height, and body mass index was performed.

RESULTS

The measurement success rate was better for thickness than for excursion. The mean (lower limit of normal) values on the right/left sides were as follows. During quiet breathing, thickness at end expiration(mm) was 1.7 (0.9)/1.6 (0.80), thickening fraction(%) was 50 (0.0)/52 (0.0), and excursion(cm) was 1.7 (0.5)/1.9 (0.5). During deep breathing, the thickening fraction was 111 (24)/107 (22), and the excursion was 4.4 (1.7)/4.1 (2.0). In multivariate analysis, body mass index was positively associated with thickness but not with the thickening fraction.

CONCLUSION

The reference values in this study were smaller than those in previous reports from Europe. Considering that thickness is influenced by body mass index, using Western reference values in Asia, where the average body mass index is lower, might not be appropriate. The thickening fraction in deep breathing is unaffected by other items and can be used more universally.

Validation of Point-of-Care ultrasound in the diagnosis of a diaphragmatic hernia

Point-of-care ultrasound (POCUS) is a sensitive, specific tool for early diagnosis of diaphragm pathology in critically ill patients. We report the case of a patient with a history of iatrogenic diaphragmatic hernia who was admitted to the Resuscitation Unit after an emergency exploratory laparotomy. As the diagnosis of diaphragmatic hernia had already been confirmed, we determined the POCUS features that establish the diagnosis of diaphragmatic hernia: (1) normal bilateral diaphragmatic shortening fraction; (2) decreased diaphragmatic excursion; and (3) cephalic position of the diaphragmatic dome (4) greater in supine than in sitting position. We also outline a systematic ultrasound examination of the diaphragm and a POCUS-based differential classification of diaphragmatic dysfunction based on the functional integrity of the peripheral muscle and central diaphragmatic tendon in critically ill patients.

A Trend towards Diaphragmatic Muscle Waste after Invasive Mechanical Ventilation in Multiple Trauma Patients-What to Expect?

Considering the prioritization of life-threatening injuries in trauma care, secondary dysfunctions such as ventilator-induced diaphragmatic dysfunction (VIDD) are often overlooked. VIDD is an entity induced by muscle inactivity during invasive mechanical ventilation, associated with a profound loss of diaphragm muscle mass. In order to assess the incidence of VIDD in polytrauma patients, we performed an observational, retrospective, longitudinal study that included 24 polytraumatized patients. All included patients were mechanically ventilated for at least 48 h and underwent two chest CT scans during their ICU stay. Diaphragmatic thickness was measured by two independent radiologists on coronal and axial images at the level of celiac plexus. The thickness of the diaphragm was significantly decreased on both the left and right sides (left side: -0.82 mm axial p = 0.034; -0.79 mm coronal p = 0.05; right side: -0.94 mm axial p = 0.016; -0.91 coronal p = 0.013). In addition, we obtained a positive correlation between the number of days of mechanical ventilation and the difference between the two measurements of the diaphragm thickness on both sides (r =0.5; p = 0.02). There was no statistically significant correlation between the body mass indexes on admission, the use of vitamin C or N-acetyl cysteine, and the differences in diaphragmatic thickness.

Clinical values of diaphragmatic movement in patients with chronic obstructive pulmonary disease

BACKGROUND

The limitation of activity due to dyspnea in chronic obstructive pulmonary disease (COPD) patients is affected by diaphragmatic dysfunction and reduced lung function. This study aimed to analyze the association between diaphragm function variables and forced expiratory volume in the first second (FEV1) and to estimate the clinical significance of diaphragm function in the correlation between COPD severity and lung function.

METHODS

This prospective, single-center, cross-sectional observational study enrolled 60 COPD patients in a respiratory outpatient clinic. Data for baseline characteristics and the dyspnea scale were collected. Participants underwent a pulmonary function test (PFT), a 6-minute walk test (6MWT), and diaphragm function by ultrasonography.

RESULTS

The right excursion at forced breathing showed the most significant correlation with FEV1 (r = 0.370, p = 0.004). The cutoff value was 6.7 cm of the right diaphragmatic excursion at forced breathing to identify the FEV1 above 50% group. In the group with a right diaphragmatic excursion at forced breathing < 6.7 cm, modified Medical Research Council (mMRC), St. George's Respiratory Questionnaire and the total distance of 6MWT showed no difference between groups with FEV1 under and above 50% (p > 0.05). In the group with ≥ 6.7 cm, mMRC and the total distance of 6MWT showed a significant difference between FEV1 under and above 50% (p = 0.014, 456.7 ± 69.7 m vs. 513.9 ± 60.3 m, p = 0.018, respectively).

CONCLUSION

The right diaphragmatic forced excursion was closely related to FEV1, and analysis according to the right diaphragmatic forced excursion-based cut-off value showed a significant difference between both groups. When the diaphragm function was maintained, there was a lot of difference in the 6MWT's factors according to the FEV1 value. Our data suggest that diaphragmatic function should be performed when interpreting PFT.

Changes in Diaphragmatic Function Induced by an Increased Inspiratory Load Experienced by Military Divers: An Ultrasound Study

Background: Inspiratory loading is experienced by military divers when they use rebreather device. Our objective was to assess the changes in diaphragm function induced by an increase in inspiratory load at values similar to those experienced by divers in real life.

Methods: We recorded the excursion and the thickness of the right hemidiaphragm in 22 healthy male volunteers under inspiratory load conditions, using ultrasound in B- and M-mode. The measurements were performed at tidal volume and during breathing at 50% of inspiratory capacity. The breathing rate was regulated and similar in the various sessions with and without load.

Results: The rebreather device used by French military divers leads to an increase in inspiratory load of close to 30 cmH₂O. Consequently, the session under load was performed using a device set to this threshold. Significant increases in the excursion and the thickening fraction of the diaphragm were observed between the sessions at tidal volume and at high volume. With addition of the inspiratory load, the excursion of the right hemidiaphragm increased significantly from 2.3 to 3.4cm at tidal volume and from 3.9 to 4.7cm at high volume. The thickening fraction increased significantly from 30.4 to 76.6% at tidal volume and from 70 to 123% at high volume. The statistical analysis demonstrated that assessment of the changes of the thickening fraction during breathing at tidal volume was the most relevant marker to assess the impact of the inspiratory load on the diaphragm.

Conclusion: Diaphragm ultrasound can be used to assess the changes in the diaphragm contraction pattern secondary to an increase in the respiratory load that can be generated by use a diving apparatus. The recording of the changes of the motion, and more importantly of the thickness of the diaphragm, during the breathing cycle is able to provide relevant information regarding the inspiratory load.

Peri-operative diaphragm ultrasound as a new method of recognizing post-operative residual curarization

Background

This study sought to evaluate the diagnostic accuracy of peri-operative diaphragm ultrasound in assessing post-operative residual curarization (PORC).

Methods

Patients undergoing non-thoracic and non-abdominal surgery under general anaesthesia were enrolled from July 2019 to October 2019 at Peking Union Medical College Hospital. A train-of-four ratio (TOFr) lower than 0.9 was considered as the gold standard for PORC. Diaphragm ultrasound parameters included diaphragmatic excursion (DE) and diaphragm thickening fraction (DTF) during quiet breathing (QB) and deep breathing (DB). The diaphragm excursion fraction (DEF) was calculated as the DE-QB divided by the DE-DB. The diaphragm excursion difference (DED) was defined as DE-DB minus DE-QB. Receiver operating characteristic curve analysis was used to determine the cut-off values of ultrasound parameters for the prediction of PORC.

Results

In total, 75 patients were included, with a PORC incidence of 54.6%. The DE-DB and DED were positively correlated with the TOFr, while the DEF was negatively correlated with the TOFr. The DE-DB cut-off value for predicting PORC was 3.88 cm, with a sensitivity of 85.4% (95% confidence interval [CI]: 70.1–93.9%), specificity of 64.7% (95% CI: 46.4–79.7%), positive likelihood ratio of 2.42 (95% CI 1.5–3.9), and negative likelihood ratio of 0.23 (95% CI: 0.1–0.5). The DED cut-off value was 1.5 cm, with a specificity of 94.2% (95% CI: 80.3–99.3%), sensitivity of 63.4% (95% CI: 46.9–77.9%), positive likelihood ratio of 10.78 (95% CI: 2.8–42.2), and negative likelihood ratio of 0.39 (95% CI: 0.3–0.6).

Conclusions

Peri-operative diaphragm ultrasound may be an additional method aiding the recognition of PORC, with DED having high specificity.

Diaphragmatic paralysis, respiratory function, and postoperative pain after interscalene brachial plexus block with a reduced dose of 10 ml levobupivacaine 0.25% versus a 20 ml dose in patients undergoing arthroscopic shoulder surgery: study protocol for the randomized controlled double-blind REDOLEV study

Background

Arthroscopic shoulder surgery causes severe postoperative pain. An interscalene brachial plexus block provides adequate analgesia, but unintended spread of the local anesthetic administered may result in a phrenic nerve block, usually associated with a nonnegligible incidence of acute hemidiaphragmatic paralysis.

The main purpose of this trial will be to analyze the incidence of hemidiaphragmatic paralysis ensuing after interscalene brachial plexus block in patients undergoing arthroscopic shoulder surgery administered a standard volume (20 ml) vs. a low volume (10 ml) of levobupivacaine 0.25%.

Methods

This will be a prospective double-blind randomized controlled single-center two-arm comparative trial. Forty-eight patients will be included. The primary goal will be to ultrasonographically determine the incidence of hemidiaphragmatic paralysis by calculating the diaphragmatic thickness ratio in each group. The secondary goals will be to compare the two arms in terms of (1) decrease in forced vital capacity and (2) in forced expiratory volume at 1 s by spirometry; (3) decrease in diaphragmatic excursion by ultrasound; (4) 24-h total intravenous morphine consumption; (5) time to first opioid request of a patient-controlled analgesia pump; and (6) postoperative complications.

Discussion

This trial will demonstrate that a low-volume interscalene brachial plexus block decreases hemidiaphragmatic paralysis following arthroscopic shoulder surgery according to spirometry and ultrasound measurements and does not provide inferior postoperative analgesia to the standard volume, as measured by opioid requirements.

Trial registration

EudraCT and Spanish Trial Register (REec) registration number: 2019-003855-12 (registered on 7 January 2020). ClinicalTrials.gov identification number: NCT04385966 (retrospectively registered on 8 May 2020). Ethics Committee approval: EC19/093 (18 December 2019).

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05216-6.

Diaphragmatic motion recorded by M-mode ultrasonography: limits of normality

Chest ultrasonography has proven to be useful in the diagnosis of diaphragm dysfunction. The aim of the present study was to determine the normal values of the motion of both hemidiaphragms recorded by M-mode ultrasonography.

Healthy volunteers were studied while in a seated position. Diaphragmatic excursions and diaphragm profiles were measured during quiet breathing, voluntary sniffing and deep breathing. Diaphragmatic excursions were assessed by M-mode ultrasonography, using an approach perpendicular to the posterior part of the diaphragm. Anatomical M-mode was used for the recording of the complete excursion during deep breathing.

The study included 270 men and 140 women. The diaphragmatic motions during quiet breathing and voluntary sniffing were successfully recorded in all of the participants. The use of anatomical M-mode was particularly suitable for measurement of the entire diaphragmatic excursion during deep breathing. The statistical analysis showed that the diaphragmatic excursions were larger in men compared to women, supporting the determination of normal values based on sex. The lower and upper limits of normal excursion were determined for men and women for both hemidiaphragms during the three manoeuvres that were investigated. The lower limits of normal diaphragmatic excursions during deep breathing should be used to detect diaphragmatic hypokinesia, i.e. 3.3 and 3.2 cm in women and 4.1 and 4.2 cm in men for the right and the left sides, respectively.

The normal values of the diaphragmatic motion and the lower and upper limits of normal excursion can be used by clinicians to detect diaphragmatic dysfunction.

These normal values of diaphragmatic motion, and the lower and upper limits of normal excursion, can be used by physicians to detect diaphragm hypokinesia and hyperkinesia, and thus diagnose diaphragmatic dysfunctionhttps://bit.ly/35R9OFk

Diaphragmatic muscle thickness and diaphragmatic function are reduced in patients with systemic lupus erythematosus compared to those with primary Sjögren's syndrome

INTRODUCTION

Systemic lupus erythematosus (SLE) is associated with an increased risk of pulmonary infections, as well as a rare condition known as shrinking lung syndrome (SLS). The diaphragm has an important role to play in lung physiology and might also play a role in these adverse events. Here, we aimed to investigate whether SLE patients have impairment in their diaphragmatic muscle thickness and function with respect to another connective-tissue disease: primary Sjögren's syndrome (pSS).

METHOD

Patients diagnosed with SLE who were in remission or who had minimal disease activity and had at least one year of follow-up were included in this study. Patients with known lung pathology and smokers were excluded. Patients with pSS constituted the second experimental group. Ultrasonographic evaluation of the diaphragmatic muscle was conducted by an experienced independent sonographer at three time points, diaphragmatic thickness during deep and quiet inspiration and maximum expiration being measured. Diaphragmatic muscle function was evaluated with maximum expiratory pressure (MEP) and maximum inspiratory pressure (MIP).

RESULTS

A total of 115 patients were studied (n = 39 SLE; n = 76 pSS). The mean ±  standard deviation (SD) thickness of the diaphragmatic muscles during quiet inspiration was significantly reduced in patients with SLE compared to patients with pSS (2.32 mm vs. 2.81 mm; p < 0.05). Similarly, the thickness during deep inspiration and at maximum deep expiration were significantly lower in SLE patients (2.88 mm vs. 3.29 mm and 1.92 mm vs. 2.33 mm, respectively; p < 0.01). MIPs and MEPs, defined as the percentages of expected values, were significantly lower in patients with SLE compared to those with pSS (80% vs. 92% and 76% vs. 120%, respectively; p < 0.05). Diaphragmatic muscle thickness during deep inspiration demonstrated a moderate correlation with MIP (r = 0.434; p = 0.001).

CONCLUSION

SLE patients had reduced diaphragmatic muscle thickness compared to those with pSS, which was associated with impaired functional tests. Further prospective studies are needed to investigate whether structural and functional impairments in diaphragmatic muscle play a role in an increased risk of pulmonary infections and SLS in patients with SLE.

Positional impairment of gas exchange during diaphragm pacing alleviated by increasing amplitude settings in congenital central hypoventilation syndrome

None

Diaphragm pacing (DP) by phrenic nerve stimulation is a modality of chronic ventilatory support in individuals with congenital central hypoventilation syndrome (CCHS). We report a 9-year-old girl with CCHS who uses DP without tracheostomy during sleep. Her parents report hypoxemia and hypercapnia related to positional changes of the body during sleep requiring frequent adjustment of pacer settings. Overnight polysomnography was performed to titrate DP settings that showed adequate gas exchange in the supine position, but intermittent hypoxemia and hypercapnia were noted in the left decubitus position without obstructive sleep apnea occurring. Subsequently, the DP amplitude settings were increased during polysomnography, thereby identifying and treating positional hypoxemia and hypercapnia in various body positions. Our case emphasizes the importance of polysomnography in children with CCHS using DP to monitor for sleep-disordered breathing and titration of DP settings to achieve optimal oxygenation and ventilation with different body positions during sleep.