Advanced waveform analysis of diaphragm surface EMG allows for continuous non-invasive assessment of respiratory effort in critically ill patients at different PEEP levels.

BACKGROUND: Respiratory effort should be closely monitored in mechanically ventilated ICU patients to avoid both overassistance and underassistance. Surface electromyography of the diaphragm (sEMGdi) offers a continuous and non-invasive modality to assess respiratory effort based on neuromuscular coupling (NMCdi). The sEMGdi derived electrical activity of the diaphragm (sEAdi) is prone to distortion by crosstalk from other muscles including the heart, hindering its widespread use in clinical practice. We developed an advanced analysis as well as quality criteria for sEAdi waveforms and investigated the effects of clinically relevant levels of PEEP on non-invasive NMCdi. METHODS: NMCdi was derived by dividing end-expiratory occlusion pressure (Pocc) by sEAdi, based on three consecutive Pocc manoeuvres at four incremental (+ 2 cmH2O/step) PEEP levels in stable ICU patients on pressure support ventilation. Pocc and sEAdi quality was assessed by applying a novel, automated advanced signal analysis, based on tolerant and strict cut-off criteria, and excluding inadequate waveforms. The coefficient of variations (CoV) of NMCdi after basic manual and automated advanced quality assessment were evaluated, as well as the effect of an incremental PEEP trial on NMCdi. RESULTS: 593 manoeuvres were obtained from 42 PEEP trials in 17 ICU patients. Waveform exclusion was primarily based on low sEAdi signal-to-noise ratio (Ntolerant = 155, 37%, Nstrict = 241, 51% waveforms excluded), irregular or abrupt cessation of Pocc (Ntolerant = 145, 35%, Nstrict = 145, 31%), and high sEAdi area under the baseline (Ntolerant = 94, 23%, Nstrict = 79, 17%). Strict automated assessment allowed to reduce CoV of NMCdi to 15% from 37% for basic quality assessment. As PEEP was increased, NMCdi decreased significantly by 4.9 percentage point per cmH2O. CONCLUSION: Advanced signal analysis of both Pocc and sEAdi greatly facilitates automated and well-defined identification of high-quality waveforms. In the critically ill, this approach allowed to demonstrate a dynamic NMCdi (Pocc/sEAdi) decrease upon PEEP increments, emphasising that sEAdi-based assessment of respiratory effort should be related to PEEP dependent diaphragm function. This novel, non-invasive methodology forms an important methodological foundation for more robust, continuous, and comprehensive assessment of respiratory effort at the bedside.

Magnetic twitch assessment of diaphragm and quadriceps weakness in critically ill mechanically ventilated patients.

Critically ill mechanically ventilated (MV) patients develop significant muscle weakness, which has major clinical consequences. There remains uncertainty, however, regarding the severity of leg weakness, the precise relationship between muscle strength and thickness, and the risk factors for weakness in MV patients. We therefore measured both diaphragm (PdiTw) and quadriceps (QuadTw) strength in MV patients using magnetic stimulation and compared strength to muscle thickness. Both PdiTw and QuadTw were profoundly reduced for MV patients, with PdiTw 19 % of normal and QuadTw 6% of normal values. There was a poor correlation between strength and thickness for both muscles, with thickness often remaining in the normal range when strength was severely reduced. Regression analysis revealed reductions in PdiTw correlated with presence of infection (p = 0.006) and age (p = 0.007). QuadTw best correlated with duration of MV (p = 0.036). Limb muscles are profoundly weak in critically ill patients, with a severity that mirrors the level of weakness observed in the diaphragm.

Assessment of magnetic flux density properties of electromagnetic noninvasive phrenic nerve stimulations for environmental safety in an ICU environment.

Diaphragm weakness affects up to 60% of ventilated patients leading to muscle atrophy, reduction of muscle fiber force via muscle fiber injuries and prolonged weaning from mechanical ventilation. Electromagnetic stimulation of the phrenic nerve can induce contractions of the diaphragm and potentially prevent and treat loss of muscular function. Recommended safety distance of electromagnetic coils is 1 m. The aim of this study was to investigate the magnetic flux density in a typical intensive care unit (ICU) setting. Simulation of magnetic flux density generated by a butterfly coil was performed in a Berlin ICU training center with testing of potential disturbance and heating of medical equipment. Approximate safety distances to surrounding medical ICU equipment were additionally measured in an ICU training center in Bern. Magnetic flux density declined exponentially with advancing distance from the stimulation coil. Above a coil distance of 300 mm with stimulation of 100% power the signal could not be distinguished from the surrounding magnetic background noise. Electromagnetic stimulation of the phrenic nerve for diaphragm contraction in an intensive care unit setting seems to be safe and feasible from a technical point of view with a distance above 300 mm to ICU equipment from the stimulation coil.

Shear Wave Elastography, a New Tool for Diaphragmatic Qualitative Assessment: A Translational Study.

Rationale: Prolonged mechanical ventilation is often associated with either a decrease (known atrophy) or an increase (supposed injury) in diaphragmatic thickness. Shear wave elastography is a noninvasive technique that measures shear modulus, a surrogate of tissue stiffness and mechanical properties. Objectives: To describe changes in shear modulus (SM) during the ICU stay and the relationship with alterations in muscle thickness. To perform a comprehensive ultrasound-based characterization of histological and force production changes occurring in the diaphragm. Methods: Translational study using critically ill patients and mechanically ventilated piglets. Serial ultrasound examination of the diaphragm collecting thickness and SM was performed in both patients and piglets. Transdiaphragmatic pressure and diaphragmatic biopsies were collected in piglets. Measurements and Main Results: We enrolled 102 patients, 88 of whom were invasively mechanically ventilated. At baseline, SM was 14.3 ± 4.3 kPa and diaphragm end-expiratory thickness was 2.0 ± 0.5 mm. Decrease or increase by more than 10% from baseline was reported in 86% of the patients for thickness and in 92% of the patients for SM. An increase in diaphragmatic thickness during the stay was associated with a decrease in SM (ß = -9.34 ± 4.41; P = 0.03) after multivariable analysis. In the piglet sample, a decrease in SM over 3 days of mechanical ventilation was associated with loss of force production, slow and fast fiber atrophy, and increased lipid droplets accumulation. Conclusions: Increases in diaphragm thickness during critical illness is associated with decreased tissue stiffness as demonstrated by shear wave ultrasound elastography, consistent with the development of muscle injury and weakness. Clinical trial registered with www.clinicaltrials.gov (NCT03550222).

Comprehensive assessment of respiratory function, a step towards early weaning from the ventilator.

Methods for assessing diaphragmatic function can be useful in determining the functional status of the respiratory system and can contribute to determining an individual's prognosis, depending on their pathology. They can also be a useful tool for making objective decisions regarding mechanical ventilation weaning and extubation. Esophageal and transdiaphragmatic pressure measurement, diaphragm ultrasound, diaphragmatic excursion, surface electromyography (sEMG) and some serum biomarkers are of increasing interest and use in clinical and intensive care settings to offer a more objective process for withdrawing mechanical ventilation; especially in the situation that we are experiencing with the increased demand for mechanical ventilation to treat patients with Covid-19-associated viral pneumonia. In this literature review, we updated the clinical and physiological indicators with more evidence to improve ventilator withdrawal techniques. We concluded that, to ensure successful extubation in a way that is useful, cost-effective, practical for health personnel and non-invasive for the patient, further studies of novel techniques such as surface electromyography should be implemented.

Ultrasound and non-ultrasound imaging techniques in the assessment of diaphragmatic dysfunction.

Diaphragm muscle dysfunction is increasingly recognized as an important element of several diseases including neuromuscular disease, chronic obstructive pulmonary disease and diaphragm dysfunction in critically ill patients. Functional evaluation of the diaphragm is challenging. Use of volitional maneuvers to test the diaphragm can be limited by patient effort. Non-volitional tests such as those using neuromuscular stimulation are technically complex, since the muscle itself is relatively inaccessible. As such, there is a growing interest in using imaging techniques to characterize diaphragm muscle dysfunction. Selecting the appropriate imaging technique for a given clinical scenario is a critical step in the evaluation of patients suspected of having diaphragm dysfunction. In this review, we aim to present a detailed analysis of evidence for the use of ultrasound and non-ultrasound imaging techniques in the assessment of diaphragm dysfunction. We highlight the utility of the qualitative information gathered by ultrasound imaging as a means to assess integrity, excursion, thickness, and thickening of the diaphragm. In contrast, quantitative ultrasound analysis of the diaphragm is marred by inherent limitations of this technique, and we provide a detailed examination of these limitations. We evaluate non-ultrasound imaging modalities that apply static techniques (chest radiograph, computerized tomography and magnetic resonance imaging), used to assess muscle position, shape and dimension. We also evaluate non-ultrasound imaging modalities that apply dynamic imaging (fluoroscopy and dynamic magnetic resonance imaging) to assess diaphragm motion. Finally, we critically review the application of each of these techniques in the clinical setting when diaphragm dysfunction is suspected.

Ultrasound assessment of diaphragmatic function in type 1 spinal muscular atrophy.

OBJECTIVE: To investigate ultrasound features of diaphragm motion and function in type 1 spinal muscular atrophy (SMA-1) patients. DESIGN: Prospective study. PATIENTS: The study cohort included SMA-1 children younger than 18-year-old. Control subjects included type 2 and type 3 SMA and other neuromuscular disorders younger than 18-year-old. METHODOLOGY: Diaphragm ultrasound evaluating diaphragmatic excursion, speed of diaphragmatic contraction, duration of the respiratory cycle, inspiratory/expiratory relationship, end-inspiratory and -expiratory thickness, thickening fraction, and pattern of contractility. The interrater reliability for each variable was established by calculation of Cohen's k coefficient. RESULTS: Twenty-three SMA-1 patients and 12 controls were evaluated. Diaphragm ultrasound values were within normal ranges in all study cohort patients and no difference was found with controls. There was a gradient of diaphragm function with SMA 1.9 subgroup having the best and SMA 1.1 having the worst parameters, particularly in end-inspiratory thickness and diaphragmatic excursion (P = .031 and P = .041, respectively). Seventy-four percent of SMA-1 patients had a dysmotility pattern of diaphragm contraction, mostly represented in SMA 1.9 subgroup (P = .001). This pattern was observed in 92.8% of children on noninvasive ventilation (NIV) for less than 16 hours/d of and in 20% patients with invasive ventilation or NIV for more than 16 hours/d (P = .027). The dysmotility pattern was never observed in the control group. The levels of interobserver agreement were high for "diaphragm irregularities," "inspiratory/expiratory relationship," and "diaphragm thickness," and good for the other variables. CONCLUSIONS: Ultrasound can be used to evaluate diaphragm function and contractility in SMA-1 children, providing additional information to the clinical examination and functional respiratory tests, describing a characteristic contractility pattern in these patients. Longitudinal studies are needed to understand the impact of diaphragm dysmotility and other parameters on long-term outcome in SMA-1 patients.

[Ultrasonographic assessment of diaphragm function in long-term mechanical ventilation patients].

Objective: To evaluate the condition of the diaphragm in patients with long-term mechanical ventilation using ultrasound technology and to analyze its relationship with ventilation time and muscle atrophy in order to clarify the reasons for diaphragm dysfunction in long-term mechanical ventilation patients. Methods: Patients admitted to the respiratory department at the Chinese PLA General Hospital between June 2018 and April 2019 with mechanical ventilation were included in this study. The enrolled patients were divided into a short-term mechanical ventilation group (7 days ≤ ventilation time<1 month) and a long-term mechanical ventilation group (mechanical ventilation time ≥ 1 month). The diaphragmatic excursion, inspiratory time, contraction rate, E-T index, diaphragm thickness, diaphragm thickness fraction (DTF), and tibialis anterior thickness were compared between the two groups. The correlation between ventilation time and diaphragm thickness was analyzed in all patients. Results: The mean diaphragm thickness and DTF were significantly lower in the long-term mechanical ventilation group than in the short-term mechanical ventilation group [(0.13±0.036) vs (0.17±0.05) cm and (0.22±0.045) vs (0.27±0.075)](all P<0.05). However, there was no significant difference in diaphragmatic excursion, inspiratory time, contraction rate, E-T index or tibialis anterior thickness between the two groups (all P>0.05). There was a significant linear correlation between ventilation time and diaphragm thickness (P<0.01). Tibialis anterior thickness was not significantly correlated with ventilation time (P>0.05). Conclusion: Diaphragm thickness and function were significantly reduced in patients with long-term mechanical ventilation, which was correlated with the duration of ventilation. Nutritional status was not the main factor affecting diaphragm thickness.

Assessment of Diaphragm Function and Pleural Pressures During Thoracentesis.

BACKGROUND: This prospective observational study reports on diaphragm excursion, velocity of diaphragm contraction, and changes in pleural pressure that occur with thoracentesis. METHODS: Twenty-eight patients with pleural effusion underwent therapeutic thoracentesis. Diaphragm excursion and velocity of diaphragm contraction were measured with M-mode ultrasonography of the affected hemidiaphragm. Pleural pressure was measured at each aliquot of 250 mL of fluid removal. Fluid removal was continued until no more fluid could be withdrawn, unless there was evidence of nonexpandable lung defined as a pleural elastance greater > 14.5 cm H2O/L and/or ipsilateral anterior chest discomfort. RESULTS: Twenty-three patients had expandable lung, and five patients had nonexpandable lung. Velocity of diaphragm contraction (mean ± SD) increased from 1.5 ± 0.4 cm/s to 2.8 ± 0.4 cm/s pre-thoracentesis and post-thoracentesis, respectively (CI, 0.93-1.61; P < .001) in subjects with expandable lung. Velocity of diaphragm contraction (mean ± SD) increased from 2.0 ± 0.4 cm/s to 2.3 ± 0.4 cm/s pre-thoracentesis and post-thoracentesis (P = .45) in subjects with nonexpandable lung. Diaphragm excursion was significantly increased in subjects with expandable lung at the end of thoracentesis; diaphragm excursion did not increase to a significant extent in patients with nonexpandable lung. CONCLUSIONS: The velocity of diaphragm contraction and diaphragm excursion increased in association with fluid removal with thoracentesis in patients with expandable lung, whereas it did not significantly change in patients with nonexpandable lung. This may derive from improvement in loading conditions of the diaphragm in patients with expandable lung related to its preload and length-tension characteristics.

Ultrasound Assessment Of Diaphragmatic Function During Acute Exacerbation Of Chronic Obstructive Pulmonary Disease: A Pilot Study.

Purpose: Impairment of diaphragmatic function is one of the main pathophysiological mechanisms of chronic obstructive pulmonary disease (COPD) and is known to be related to acute exacerbation. Ultrasonography (US) allows for a simple, non-invasive assessment of diaphragm kinetics. The purpose of this study was to investigate the changes in diaphragmatic function during acute exacerbation of COPD, by US. Methods: This single-center, prospective study included patients with acute exacerbation of COPD symptoms. US measurements were performed within 72 hrs after exacerbation and after improvement of symptoms. Diaphragmatic excursion and its thickening fraction (TF) were measured as markers of diaphragmatic function. TF was calculated as (thickness at end inspiration - thickness at end expiration)/thickness at end expiration. Results: Ten patients were enrolled. All patients were male, and the mean age was 79.8 years. The TF of the right diaphragm showed a significant increase from the initial to the follow-up values (80.1 ± 104.9 mm vs. 159.5 ± 224.6 mm, p = 0.011); however, the diaphragmatic excursion did not vary significantly between the initial and follow-up values (22 ± 6 mm vs 23 ±12 mm). The change in excursion between the stable and exacerbation periods was positively correlated with time to the next exacerbation and negatively correlated with the time taken to recover from the exacerbation. Conclusion: These data support the possibility that a defect in diaphragm thickening is related to acute exacerbation of COPD.

Serial ultrasound assessment of diaphragmatic function and clinical outcome in patients with amyotrophic lateral sclerosis.

BACKGROUND: Diaphragmatic assessment by ultrasound (US) is a non-invasive and useful method in the clinical management of patients with Amyotrophic Lateral Sclerosis (ALS). The aim of our observational study was to evaluate the impact of serial assessment of the diaphragmatic function by US on long-term outcomes in a series of patients suffering from ALS and to correlate US indices of diaphragmatic function and respiratory function tests with these outcomes. METHODS: A cohort of 39 consecutive patients has been followed up to 24 months. Both lung volume (forced vital capacity, FVC) and diaphragmatic pressure generating capacity (by sniff inspiratory nasal pressure (SNIP) and by both US thickening fraction, ΔTdi, and the ratio of the thickening fraction between tidal volume and maximal lung capacity, ΔTmax) were recorded at baseline and every 3 months. Parameters were then correlated with outcomes (nocturnal hypoventilation, daily hypercapnia, start of ventilatory support (NIV), and death at 1 year) over time. RESULTS: The occurrence of ΔTmax > 0.75 increased the risk to start NIV (HR = 5.6, p = 0.001) and to die (HR = 3.7, p = 0.0001) compared with patients maintaining lower values. Moreover, compared with the occurrence of FVC < 50% of predicted, ΔTmax > 0.75 appeared slightly better correlated with NIV commencement within 6 months. CONCLUSIONS: Serial diaphragmatic assessment by ultrasound is a useful and accurate method to predict the initiation of NIV earlier in patients with ALS.

Diaphragmatic Ultrasound Assessment in Subjects With Acute Hypercapnic Respiratory Failure Admitted to the Emergency Department.

BACKGROUND: Early identification of noninvasive ventilation (NIV) outcome predictors in patients with COPD who are experiencing acute hypercapnic respiratory failure consequent to exacerbation or pneumonia is a critical issue. The primary aim of this study was to investigate the feasibility of performing diaphragmatic ultrasound for excursion, thickness, and thickening fraction in highly dyspneic subjects with COPD admitted to the emergency department for exacerbation or pneumonia, before starting NIV (T0) and after the first (T1) and second hour (T2) of treatment. Secondarily, we determined whether these variables predicted early NIV failure. METHODS: Adult subjects with COPD admitted to the emergency department for exacerbation or pneumonia requiring NIV were eligible. Right-sided diaphragmatic excursion, bilateral thickness, thickening fraction, and arterial blood gas analyses were performed at T0, T1, and T2. Feasibility was estimated by considering the number of subjects whose diaphragmatic function could be evaluated at each time point. At T2, subjects were classified in 2 subgroups according to early NIV failure, which was defined as the inability to achieve a pH ≥ 7.35; the ability to achieve pH ≥ 7.35 indicated NIV success. RESULTS: Of the 22 subjects enrolled, 21 underwent complete diaphragm ultrasound evaluation (ie, right excursion and bilateral thickness at T0, T1, and T2) for a total of 63 excursion and 126 thickness assessments. At T2, 12 NIV successes and 9 NIV failures were recorded. Diaphragmatic excursion was greater in NIV successes than in NIV failures at T0 (1.92 [1.22-2.54] cm versus 1.00 [0.60-1.41] cm, P = .02), at T1 (2.14 [1.76-2.77] cm versus 0.93 [0.82-1.27] cm, P = .007), and at T2 (1.99 [1.63-2.54] cm versus 1.20 [0.79-1.41] cm, P = .008), respectively. Diaphragmatic thickness and thickening fraction were similar in both groups. CONCLUSIONS: In our emergency department setting, diaphragm ultrasound was a feasible and reliable tool to monitor highly dyspneic acute hypercapnic respiratory failure subjects with COPD undergoing NIV. (ClinicalTrials.gov registration NCT03314883.).

[Ultrasound Assessment of Ventilator-induced Diaphragmatic Dysfunction in Paediatrics]. / Avaliação Ecográfica da Disfunção Diafragmática Induzida pelo Ventilador em Idade Pediátrica.

INTRODUCTION: Invasive mechanical ventilation contributes to ventilator-induced diaphragmatic dysfunction, delaying extubation and increasing mortality in adults. Despite the possibility of having a higher impact in paediatrics, this dysfunction is not routinely monitored. Diaphragm ultrasound has been proposed as a safe and non-invasive technique for this purpose. The aim of this study was to describe the evolution of diaphragmatic morphology and functional measurements by ultrasound in ventilated children. MATERIAL AND METHODS: Prospective exploratory study. Children admitted to Paediatric Intensive Care Unit requiring mechanical ventilation > 48 hours were included. The diaphragmatic thickness, excursion and the thickening fraction were assessed by ultrasound. RESULTS: Seventeen cases were included, with a median age of 42 months. Ten were male, seven had comorbidities and three in seventeen had malnutrition at admission. The median time under mechanical ventilation was seven days. The median of the initial and minimum diaphragmatic thickness was 2.3 mm and 1.9 mm, respectively, with a median decrease in thickness of 13% under pressure-regulated volume control. Diaphragmatic atrophy was observed in 14/17 cases. Differences in the median thickness variation were found between patients with sepsis and without (0.70 vs 0.25 mm; p = 0.019). During pressure support ventilation there was a tendency to increase diaphragmatic thickness and excursion. Extubation failure occurred for diaphragmatic thickening fraction ≤ 35%. DISCUSSION: Under pressure-regulated volume control there was a tendency for a decrease in diaphragmatic thickness. In the pre-extubation stage under pressure support, there was a tendency for it to increase. These results suggest that, by titrating ventilation using physiological levels of inspiratory effort, we can reduce the diaphragmatic morphological changes associated with ventilation. CONCLUSION: The early recognition of diaphragmatic changes may encourage a targeted approach, namely titration of ventilation, in order to reduce ventilator-induced diaphragmatic dysfunction and its clinical repercussions.

Introdução: A ventilação mecânica invasiva condiciona disfunção diafragmática, atrasando a extubação e aumentando a mortalidade em adultos. Em pediatria, apesar de eventualmente mais relevante, essa disfunção não é sistematicamente avaliada. A ecografia diafragmática tem sido proposta como uma técnica não invasiva e segura para esse fim. O objetivo deste estudo foi descrever a evolução dos índices ecográficos de morfologia e função diafragmáticas em crianças ventiladas. Material e Métodos: Estudo exploratório, prospetivo. Foram incluídas crianças admitidas num Serviço de Cuidados Intensivos Pediátricos sob ventilação mecânica invasiva > 48 horas e realizadas medições ecográficas de espessura, excursão e fração de espessamento diafragmáticas. Resultados: Foram incluídos 17 casos. Mediana de idades: 42 meses. Eram do género masculino 10/17, tinham comorbilidades 7/17 e manifestavam desnutrição na admissão 3/17 casos. Mediana do tempo sob ventilação invasiva: sete dias. Medianas das espessuras diafragmáticas inicial e mínima: 2,3 e 1,9 mm, respetivamente, tendo-se observado uma diminuição mediana da espessura de 13% sob volume controlado regulado por pressão. Observou-se atrofia diafragmática em 14/17 casos. Verificaram-se diferenças na mediana da variação da espessura entre os grupos com e sem sépsis (0,70 vs 0,25 mm; p = 0,019). Durante a ventilação em pressão de suporte, observou-se uma tendência para aumento da espessura e excursão diafragmáticas. Ocorreu falência de extubação parafração de espessamento ≤ 35%. Discussão: Sob volume controlado regulado por pressão verificou-se tendência para diminuição da espessura diafragmática. Sob pressão de suporte, verificou-se uma tendência para o seu aumento. Estes resultados sugerem que, titulando a ventilação, podemos reduzir as alterações morfológicas diafragmáticas associadas à ventilação. Conclusão: O reconhecimento precoce de alterações diafragmáticas poderá fomentar uma abordagem dirigida, de forma a limitar a disfunção diafragmática induzida pelo ventilador e suas repercussões.

Ultrasound Assessment of Respiratory Workload With High-Flow Nasal Oxygen Versus Other Noninvasive Methods After Chest Surgery.

OBJECTIVE: To compare the respiratory workload using the diaphragm thickening fraction (DTf) determined by sonography during high-flow nasal oxygen (HFNO), standard oxygen therapy (SOT), and noninvasive bilevel positive airway pressure support (BIPAP) in patients with acute respiratory failure (ARF) after cardiothoracic surgery. DESIGN: Prospective controlled clinical trial. SETTING: A French 23-bed cardiothoracic surgical intensive care unit. PARTICIPANTS: Nonintubated patients with ARF after cardiothoracic surgery or while awaiting lung transplantation. INTERVENTIONS: HFNO (50 L/min), SOT via a standard facemask, and BIPAP (pressure support, 4 cmH2O; positive end-expiratory pressure [PEEP], 4 cmH2O), with FIO2 kept constant were successively applied and compared. With BIPAP, pressure support or PEEP increments up to 8 cmH2O were compared with baseline settings. Each measurement was made after stable breathing for 5 minutes. MEASUREMENTS AND MAIN RESULTS: Fifty patients aged 60.0 ± 12.2 years were enrolled, including 14 (28%) with obesity. Mean PaO2/FIO2 was 153 ± 55 mmHg. DTf was lower with HFNO and BIPAP than with SOT (respectively 21.2% ± 15.1% v 30.9% ± 21.1% and 17.8% ± 19.1% v 30.9% ± 21.1%, p < 0.001) and was not different with HFNO versus BIPAP (p = 0.22). With BIPAP, increasing pressure support to 8 cmH2O decreased DTf (21.0% ± 14.3% v 28.8% ± 19.8%, p = 0.009), whereas increasing PEEP to 8 cmH2O did not (25.2% ± 17.2% v 28.8% ± 19.8%, p = 0.79). Tidal volume increased to 10.6 ± 3.4 mL/kg with 8 cmH2O pressure support v 8.8 ± 2.7 mL/kg with 4 cmH2O pressure support (p < 0.001). CONCLUSION: HFNO provides a comparable respiratory workload decrease compared with BIPAP at lower levels of pressure support and PEEP compared with SOT. Increasing BIPAP pressure support may provide higher levels of assistance but carries a risk of overdistension.

Ultrasonographic assessment of organs other than the heart in patients with heart failure.

The number of patients with heart failure has been dramatically increasing in Japan in association with aging of the society. This phenomenon is referred to as a heart failure pandemic. The fundamental origin of heart failure is cardiac dysfunction. Echocardiography is widely used to assess cardiac function, as well as to diagnose heart diseases that cause cardiac dysfunction. However, the severity of heart failure is not necessarily correlated with that of cardiac dysfunction. This is partly explained by the fact that heart failure induces dysfunction of organs other than the heart through hemodynamic deterioration and neurohumoral changes. In addition, one of the characteristics of patients with heart failure, particularly elderly patients, is the presence of numerous comorbidities. Symptoms of heart failure are not specific, and assessment of cardiac function, particularly left ventricular diastolic function, has not been established. Thus, ultrasonographic assessment of organs other than the heart helps the diagnosis of heart failure, assessment of the severity of heart failure, and development of our understanding of the pathophysiology in each patient. This review summarizes current knowledge about the usefulness of ultrasonographic assessment of organs other than the heart in heart failure.

Echographic Assessment of Diaphragmatic Function in Duchenne Muscular Dystrophy from Childhood to Adulthood.

BACKGROUND: Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic muscle disorder. Respiratory muscle function is classically affected in this disease. Ultrasound recently emerged as a non-invasive tool to assess diaphragm function. However, there are only a few studies using diaphragm ultrasound (US) in DMD. PURPOSE: We aimed to assess diaphragm ultrasound patterns in DMD, their relationship with age and their association with home mechanical ventilation (HMV). METHODS: We included DMD patients followed at Raymond Poincaré Hospital who benefited from diaphragm ultrasound and pulmonary function tests. RESULTS: There were 110 DMD patients and 17 male sex-matched healthy subjects included. In all, 94% of patients were permanent wheelchair users. Median body mass index (BMI) was 18 kg/m2. DMD patients disclosed a reduced forced vital capacity (VC) (12% of predicted value), and 78% of patients were on HMV. In patients, right and left diaphragmatic motions on deep inspiration were reduced and end expiratory diaphragm thickness was borderline normal. In patients, right and left diaphragmatic thickening fractions (TF) were reduced 12.7% and 15.5%, respectively. Age and end expiratory thickness were significantly inversely associated (p = 0.005 for the right diaphragm, p = 0.018 for the left diaphragm). Diaphragm TF was significantly inversely associated with age (p = 0.001 for the right side, p < 0.0001 for the left side). Right and left inspiratory diaphragm motions were significantly inversely associated with age (p < 0.0001). CONCLUSION: This study describes the severity of diaphragm dysfunction in patients with DMD. Diaphragm US may be a non-invasive outcome measure for DMD.

Ultrasound assessment of diaphragmatic dysfunction as a predictor of weaning outcome from mechanical ventilation: a systematic review and meta-analysis.

OBJECTIVE: The aim of this systematic review was to assess the diaphragmatic dysfunction (DD) as a predictor of weaning outcome. BACKGROUND: Successful weaning depends on several factors: muscle strength, cardiac, respiratory and metabolic. Acquired weakness in mechanical ventilation is a growing important cause of weaning failure. With the development of ultrasonography, DD can be evaluated with ultrasound in weakness patients to predict weaning outcomes. METHODS: The Cochrane Library, PubMed, Embase, Ovid Medline, WanFang Data and CNKI were systematically searched from the inception to September 2017. Ultrasound assessment of DD in adult mechanical ventilation patients was included. Two independent investigators assessed study quality in accordance with the Quality Assessment of Diagnostic Accuracy Studies-2 tool. The primary outcome was diaphragmatic thickness and excursion in the weaning success and failure group. The secondary outcome was the influence of DD on weaning outcome. RESULTS: Eleven studies involving a total of 436 patients were included. There were eight studies comparing diaphragmatic excursion (DE), five comparing the diaphragmatic thickening fraction (DTF) and two comparing DD between groups with and without successful weaning. Overall, the DE or DTF had a pooled sensitivity of 0.85 (95% CI 0.77 to 0.91) and a pooled specificity of 0.74 (95% CI 0.66 to 0.80) for predicting weaning success. There was high heterogeneity among the included studies (I2=80%; p=0.0006). The rate of weaning failure was significantly increased in patients with DD (OR 8.82; 95% CI 3.51 to 22.13; p<0.00001). CONCLUSIONS: Both DE and DTF showed good diagnostic performance to predict weaning outcomes in spite of limitations included high heterogeneity among the studies. DD was found to be a predictor of weaning failure in critically ill patients.

Utility of ultrasound assessment of diaphragmatic function before and after pulmonary rehabilitation in COPD patients.

BACKGROUND: Pulmonary rehabilitation (PR) may improve respiratory symptoms and skeletal muscle strength in patients with COPD. We aimed to evaluate changes in ultrasound (US) measurements of diaphragmatic mobility and thickness after PR in COPD patients and to test its correlation with PR outcomes. METHODS: Twenty-five COPD patients were enrolled and underwent a diaphragm US assessment before and after a 12-week PR program. RESULTS: We found a correlation between the intraindividual percentage of change in the diaphragmatic length of zone of apposition at functional residual capacity (ΔLzapp%) and the change in 6-minute walking distance (6MWD) after PR (rho=0.49, P=0.02). ΔLzapp% was significantly higher in patients with improved 6MWD and COPD Assessment Test (CAT) score (mean rank=12.03±2.57 vs 6.88±4.37; P=0.02). A ΔLzapp% of ≥10% was able to discriminate among patients with improved 6MWD, with a sensitivity of 83% and a specificity of 74%. The area under the receiver operating characteristic curve for ΔLzapp% was 0.83. A cutoff value of ≥9% of ΔLzapp% had a positive predictive value in discriminating a reduction in ≥2 points of CAT score after PR, with a sensitivity and a specificity of 80% and 62%, respectively. CONCLUSION: Diaphragm US assessment represents a useful prognostic marker of PR outcomes in COPD patients.

Critical Assessment of the mdx Mouse with Ex Vivo Eccentric Contraction of the Diaphragm Muscle.

Muscle function and health progressively deteriorate during the progression of muscle dystrophies. The ability to objectively characterize muscle function and muscle damage is useful not only when comparing variants of dystrophy models, but also for characterizing the effects of interventions aiming to improve or halt the progressive decline of muscle function and muscle health. The protocols in this chapter describe the use of ex vivo eccentric contraction of the diaphragm muscle as a measure of muscle susceptibility to damage. Because muscle has a robust regenerative capacity, unhealthy muscle may be functionally close to normal; therefore, protocols for ex vivo characterization of muscle are often essential for assessing the effects of interventions. Additional methods that can be applied for assessment of dystrophic muscle are also highlighted. © 2018 by John Wiley & Sons, Inc.

Assessment of diaphragmatic thickness by ultrasonography in Duchenne muscular dystrophy (DMD) patients.

INTRODUCTION: In Duchenne muscular dystrophy (DMD) the assessment of diaphragmatic function is crucial because respiratory muscle weakness can cause respiratory failure. We aimed to noninvasively assess diaphragmatic function in DMD by measuring diaphragmatic thickness by ultrasonography, under the hypothesis that the progressive decrease of lung function is related to alterations of diaphragmatic thickness. METHODS: Forty-four DMD patients and thirteen healthy controls were enrolled and subdivided into three age groups. Diaphragmatic thickness was measured during quiet breathing, inspiratory capacity, maximal inspiratory pressure and expiratory pressure maneuvers. RESULTS: In DMD, absolute values of diaphragmatic thickness were significantly lower than in controls in the majority of the manoeuvers and diaphragmatic thickness significantly decreased with age at end-expiration, remaining constant at end-inspiration and during maximal inspiratory pressure maneuvers. Comparing to controls, absolute values of diaphragmatic thickness and diaphragmatic thickness variations were significantly lower (p<0.001), with the exception of quiet breathing and maximal expiratory pressure maneuvers in the youngest DMD. During maximal inspiratory pressure maneuver, variation of diaphragmatic thickness was not significantly different in the all groups, nevertheless maximal inspiratory pressure decreases with age. CONCLUSIONS: The diaphragm is prone to pseudo-hypertrophy in the youngest DMD, and to progressive atrophy in middle-age and oldest DMD. Diaphragm impairment could be expressed as a dissociation between muscle drive and muscle developed force. Ultrasonography could be used as a noninvasive method to assess progressive diaphragmatic weakness.