Diaphragmatic Pacing: Is There a Benefit?

The diaphragm is the primary muscle of respiration and its injury can cause diaphragm dysfunction and respiratory deficits. Respiratory compromise has historically been managed with mechanical ventilation, however, its use has also been shown to result in poor functional outcomes. Therefore, stimulation of the phrenic nerve, called diaphragm pacing, has been used to replace and/or delay the need for mechanical ventilation. This article will review the relevant literature on diaphragm pacing, discuss the physiology of diaphragm dysfunction in a variety of patient populations, and address whether diaphragm pacing is a valuable and effective option for treatment of respiratory failure.

Growth differentiation factor-15 as a biomarker of strength and recovery in survivors of acute respiratory failure

Muscle mitochondrial dysfunction is implicated in intensive care unit-acquired weakness, but there is no serum biomarker of muscle mitochondrial function for critical illness survivors. Higher serum growth differentiation factor-15 (GDF-15) is a biomarker of inherited mitochondrial myopathy disease and is associated with mortality in several age-related diseases. Among 142 older (age ≥ 65 years) survivors of acute respiratory failure, we found that higher serum GDF-15 measured during the week prior to hospital discharge was cross-sectionally associated with weaker diaphragm, limb and hand-grip strength, and longitudinally associated with lower rates of functional recovery over 6 months, independent of age, sex, pre-existing disability, comorbidity, frailty, Acute Physiology and Chronic Health Evaluation II scores and concurrent interleukin-6 levels.

[Ultrasound Assessment of Ventilator-induced Diaphragmatic Dysfunction in Paediatrics]

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.

Ethyl pyruvate attenuates ventilation-induced diaphragm dysfunction through high-mobility group box-1 in a murine endotoxaemia model

Mechanical ventilation (MV) can save the lives of patients with sepsis. However, MV in both animal and human studies has resulted in ventilator-induced diaphragm dysfunction (VIDD). Sepsis may promote skeletal muscle atrophy in critically ill patients. Elevated high-mobility group box-1 (HMGB1) levels are associated with patients requiring long-term MV. Ethyl pyruvate (EP) has been demonstrated to lengthen survival in patients with severe sepsis. We hypothesized that the administration of HMGB1 inhibitor EP or anti-HMGB1 antibody could attenuate sepsis-exacerbated VIDD by repressing HMGB1 signalling. Male C57BL/6 mice with or without endotoxaemia were exposed to MV (10 mL/kg) for 8 hours after administrating either 100 mg/kg of EP or 100 mg/kg of anti-HMGB1 antibody. Mice exposed to MV with endotoxaemia experienced augmented VIDD, as indicated by elevated proteolytic, apoptotic and autophagic parameters. Additionally, disarrayed myofibrils and disrupted mitochondrial ultrastructures, as well as increased HMGB1 mRNA and protein expression, and plasminogen activator inhibitor-1 protein, oxidative stress, autophagosomes and myonuclear apoptosis were also observed. However, MV suppressed mitochondrial cytochrome C and diaphragm contractility in mice with endotoxaemia (P < 0.05). These deleterious effects were alleviated by pharmacologic inhibition with EP or anti-HMGB1 antibody (P < 0.05). Our data suggest that EP attenuates endotoxin-enhanced VIDD by inhibiting HMGB1 signalling pathway.

Alterations in diaphragmatic function assessed by ultrasonography in mechanically ventilated patients with sepsis

PURPOSE

To assess alteration of diaphragmatic function by ultrasonography in a population of mechanically ventilated patients with or without sepsis.

METHODS

We performed a prospective, 6-month, single-center, observational cohort study. Mechanically ventilated septic and nonseptic patients were studied within 24 hours following intubation and before the moment of ventilator liberation. Diaphragm thickness and contractile activity (quantified by diaphragmatic thickening fraction, DTF) were measured by ultrasonography at the zone of apposition. Intraobserver and interobserver reproducibility were measured.

RESULTS

Fifty-two critically ill patients were included, 28 with sepsis and 24 without sepsis. Upon initiation of ventilation, DTF was lower in septic than that in nonseptic patients (P = 0.03). No difference was observed between septic and nonseptic patients for diaphragm thickness. Mean 188 ± 111 hours after the first measurement, both diaphragm thickness and DTF decreased significantly compared with first measurements in septic and nonseptic patients, all P < 0.001. Diaphragm thickness decreased by 9.1 ± 10.7% in nonseptic and by 16.0 ± 13.5% in septic patients, P = 0.049. DTF decreased by 15.2 ± 21.3% in nonseptic and by 30.7 ± 22.0% in septic patients, P = 0.013.

CONCLUSIONS

Mechanically ventilated patients with sepsis were associated with an earlier and more severe diaphragm dysfunction compared with patients without sepsis.

ULTRASOUND IN THE DIAGNOSIS AND MONITORING OF AMYOTROPHIC LATERAL SCLEROSIS: A REVIEW

Neuromuscular ultrasound is complementary to electrodiagnostic (EDx) testing and is useful in enhancing the diagnosis of mononeuropathies, peripheral nerve trauma, and demyelinating polyneuropathies. There is increasing interest in using ultrasound both to aid in the diagnosis of amyotrophic lateral sclerosis (ALS) and to monitor its progression. In this article we review the relevant literature on ultrasound in ALS. Ultrasound is more sensitive than EDx in identifying fasciculations in patients with ALS. It can detect decreased muscle thickness, increased muscle echointensity and echovariance, and reduced peripheral nerve size in these patients. Ultrasound is also a helpful tool in assessment of diaphragm function. Although additional studies are required to define the exact role of ultrasound in the evaluation and monitoring of ALS, it can improve the diagnostic yield in patients when ALS is suspected, but insufficiently supported, by clinical and EDx examinations. Muscle Nerve 60: 114-123, 2019.

Diaphragm sniff ultrasound: Normal values, relationship with sniff nasal pressure and accuracy for predicting respiratory involvement in patients with neuromuscular disorders

Background

In patients with neuromuscular disorders, assessment of respiratory function relies on forced vital capacity (FVC) measurements. Providing complementary respiratory outcomes may be useful for clinical trials. Diaphragm sniff ultrasound (US) is a noninvasive technique that can assess diaphragm function that may be affected in patients with neuromuscular disorders.

Purpose

We aimed to provide normal values of sniff diaphragm ultrasound, to assess the relationship between sniff diaphragm US, vital capacity (VC) and sniff nasal pressure. Additionally, we aimed to evaluate the diagnostic accuracy of sniff diaphragm US for predicting restrictive pulmonary insufficiency.

Materials and methods

We included patients with neuromuscular disorders that had been tested with a sniff diaphragm US and functional respiratory tests. Healthy subjects were also included to obtain normal diaphragm sniff ultrasound. We performed diaphragm tissue Doppler imaging (TDI) and time movement (TM) diaphragm echography combined with sniff maneuver.

Results

A total of 89 patients with neuromuscular diseases and 27 healthy subjects were included in our study. In patients, the median age was 32 years [25; 50] and the median FVC was 34% of predicted [18; 55]. Sniff diaphragm motion using TM ultrasound was significantly associated with sniff nasal pressure, both for the right hemidiaphragm (r = 0.6 p <0.0001) and the left hemidiaphragm (r = 0.63 p = 0.0008). Right sniff peak TDI velocity was also significantly associated with FVC (r = 0.72, p<0.0001) and with sniff nasal pressure (r = 0.66 p<0.0001). Sniff diaphragm ultrasound using either TM mode or TDI displayed significant accuracy for predicting FVC<60% with an area under curve (AUC) reaching 0.93 (p<0.0001) for the right sniff diaphragm ultrasound in TM mode and 0.86 (p<0.001) for right peak diaphragm TDI velocity.

Conclusion

Sniff diaphragm TM and TDI measures were significantly associated with sniff nasal pressure. Sniff diaphragm TM and TDI had a high level of accuracy to reveal respiratory involvement in patients with neuromuscular disorders. This technique is useful to assess and follow up diaphragm function in patients with neuromuscular disorders. It may be used as a respiratory outcome for clinical trials.

Tempol treatment shows phenotype improvement in mdx mice

Considering potential Tempol effects on mdx muscle fibers, in this study we evaluated its effects on relevant dystrophic phenotypic characteristics, such as muscle degeneration, inflammatory process and angiogenesis, which as yet have not been investigated. Mdx mice were randomly assigned into three groups: mdxS, the control group receiving intraperitoneal (i.p.) injections of saline solution (100μL); mdxP, positive control group receiving prednisolone (1mg/kg) by oral gavage; and mdxT, treated group receiving i.p. injections of tempol (100 mg/kg). C57BL/10 mice were also used as controls. Tempol treatment promoted gain in muscle strength and reduced myonecrosis and inflammatory response in the dystrophic diaphragm (DIA) and biceps brachii (BB) muscles. No evidence of Tempol's beneficial performance on angiogenesis in DIA and BB mdx muscles was found. The findings presented here show that Tempol treatment improves dystrophic phenotype, supporting its use as a potential therapeutic strategy in DMD.

[Anatomical features and biomechanical properties of the diaphragm in pathogenesis of hiatal hernia]

OBJECTIVE

To study changes of diaphragm and esophageal-diaphragmatic junction depending on age and constitutional features.

MATERIAL AND METHODS

We studied changes of diaphragm and esophageal-diaphragmatic junction depending on age and constitutional features by using of 40 cadaveric specimens (people aged 19-75 years).

RESULTS

Esophageal-aortic ligament is observed rarer with age. This ligament is poorly developed in brachiomorphic body type while diaphragmatic-cardiac ligament is generally absent as a rule. This is a predisposing factor for weakening this area. It was revealed that reduced strength and elasticity (especially esophageal-aortic and esophageal-diaphragmatic ligaments) is one of the key factors in the development of hiatal hernia. It is especially relevant for brachiomorphic body type, the 2^nd mature and elderly age. The 2^nd mature period is associated with reduced diameter and kinking of great arteries, that leads to 1.5-2 times decrease of arterial capacity of the diaphragm. Therefore, hiatal hernia repair using own tissues may be insufficient and accompanied by recurrence in persons with brachiomorphic body type in the 2^nd mature period.

CONCLUSION

Analysis of biomechanical data and anatomical features of the diaphragm may be useful to predict recurrent hiatal hernia.

Breathing Hydrogen-Oxygen Mixture Decreases Inspiratory Effort in Patients with Tracheal Stenosis

BACKGROUND

Hydrogen-oxygen mixture (H2-O2) may reduce airway resistance in patients with acute severe tracheal stenosis, yet data supporting the clinical use of H2-O2 are insufficient.

OBJECTIVES

To evaluate the efficacy and safety of breathing H2-O2 in acute severe tracheal stenosis.

METHODS

Thirty-five consecutive patients with severe acute tracheal stenosis were recruited in this prospective self-control study. Air, H2-O2 and O2 inhalation was given in 4 consecutive breathing steps: air for 15 min, H2-O2 (6 L per min, H2:O2 = 2: 1) for 15 min, oxygen (3 L per min) for 15 min, and H2-O2 for 120 min. The primary endpoint was inspiratory effort as assessed by diaphragm electromyography (EMGdi); the secondary endpoints were transdiaphragmatic pressure (Pdi), Borg score, vital signs, and impulse oscillometry (IOS). The concentration of H2 in the ambient environment was obtained with 12 monitors. Adverse reactions during the inhalation were recorded.

RESULTS

The mean reduction in the EMGdi under H2-O2 was 10.53 ± 6.83%. The EMGdi significantly decreased during 2 H2-O2 inhalation steps (Steps 2 and 4) compared with air (Step 1) and O2 (Step 3) (52.95 ± 15.00 vs. 42.46 ± 13.90 vs. 53.20 ± 14.74 vs. 42.50 ± 14.12% for Steps 1 through 4, p < 0.05). The mean reduction in the Pdi under H2-O2 was 4.77 ± 3.51 cmH2O. Breathing H2-O2 significantly improved the Borg score and resistance parameters of IOS but not vital signs. No adverse reactions occurred. H2 was undetectable in the environment throughout the procedure.

CONCLUSIONS

Breathing H2-O2 may reduce the inspiratory effort in patients with acute severe tracheal stenosis and can be used for this purpose safely.

Respiratory electrophysiologic studies in chronic obstructive pulmonary disease

Respiratory failure is common during acute exacerbation of chronic obstructive pulmonary disease (AE-COPD). Phrenic nerve conduction (PNC), transcranial magnetic stimulation (TMS), and cervical magnetic stimulation (CMS) are of great value in identifying the feature and site of AE-COPD.PNC, TMS, and CMS were performed in 20 AE-COPD patients with respiratory failure, and re-examined after weaning. Latencies and amplitudes of the diaphragmatic compound muscle action potential (dCMAP), motor evoked potential of the diaphragm (dMEP) evoked by TMS and CMS, and central motor conduction time (CMCT) were measured. Blood gas analysis and serum electrolyte levels were also evaluated. The results were compared with those from 20 healthy subjects.AE-COPD patients showed prolonged CMCT and latencies of dCMAP and dMEP, decreased amplitudes of dCMAP and dMEP evoked by CMS, while CMCT and the latency of dMEP evoked by TMS were shortened after weaning. Significant correlation was identified between arterial blood gas analysis, serum electrolyte levels, disease duration, the duration of mechanical ventilation and the electrophysiological findings in AE-COPD patients prior to weaning.The central and peripheral respiratory pathway is involved in AE-COPD. Central respiratory pathway function is improved after weaning in AE-COPD patients with respiratory failure.

Impact of diaphragm function parameters on balance maintenance

The diaphragm is well known for its role as the principal muscle of respiration. However, according to previous studies, its role is multifactorial, from breathing through pain perception, regulation of emotional sphere, collaborating in gastroesophageal functions, facilitating the venous and lymphatic return, to an essential role in the maintenance of lumbar spine stability. The purpose of the study was to examine whether diaphragm function parameters (thickness and range of motion) are associated with static balance maintenance. A total of 142 participants were examined and divided into three groups: G1-patients qualified for lung resection due to cancer; G2 -patients after lobe resection; G3 -healthy subjects. Diaphragm thickness and excursion was measured using ultrasonography. Stabilometric parameters of balance were assessed by Zebris FDM-S platform. Greater diaphragm thickening during active breathing and diaphragm thickness fraction were associated with better static balance parameters. Limitation of diaphragm motion during quiet breathing and deep breathing was linked to balance disorders. There was no correlation between diaphragm muscle excursion during sniff maneuvers and balance parameters. Deterioration of diaphragm function observed after thoracic surgery was closely related with deterioration of balance maintenance. Impairment of diaphragm function manifested by decrease of muscle thickness and movement restriction is strongly associated with balance disorders in a clinical sample and among healthy subjects.

Recovery of respiratory function in mdx mice co-treated with neutralizing interleukin-6 receptor antibodies and urocortin-2

KEY POINTS

Impaired ventilatory capacity and diaphragm muscle weakness are prominent features of Duchenne muscular dystrophy, with strong evidence of attendant systemic and muscle inflammation. We performed a 2-week intervention in young wild-type and mdx mice, consisting of either injection of saline or co-administration of a neutralizing interleukin-6 receptor antibody (xIL-6R) and urocortin-2 (Ucn2), a corticotrophin releasing factor receptor 2 agonist. We examined breathing and diaphragm muscle form and function. Breathing and diaphragm muscle functional deficits are improved following xIL-6R and Ucn2 co-treatment in mdx mice. The functional improvements were associated with a preservation of mdx diaphragm muscle myosin heavy chain IIx fibre complement. The concentration of the pro-inflammatory cytokine interleukin-1β was reduced and the concentration of the anti-inflammatory cytokine interleukin-10 was increased in mdx diaphragm following drug co-treatment. Our novel findings may have implications for the development of pharmacotherapies for the dystrophinopathies with relevance for respiratory muscle performance and breathing.

ABSTRACT

The mdx mouse model of Duchenne muscular dystrophy shows evidence of hypoventilation and pronounced diaphragm dysfunction. Six-week-old male mdx (n = 32) and wild-type (WT; n = 32) mice received either saline (0.9% w/v) or a co-administration of neutralizing interleukin-6 receptor antibodies (xIL-6R; 0.2 mg kg-1 ) and corticotrophin-releasing factor receptor 2 agonist (urocortin-2; 30 μg kg-1 ) subcutaneously over 2 weeks. Breathing and diaphragm muscle contractile function (ex vivo) were examined. Diaphragm structure was assessed using histology and immunofluorescence. Muscle cytokine concentration was determined using a multiplex assay. Minute ventilation and diaphragm muscle peak force at 100 Hz were significantly depressed in mdx compared with WT. Drug treatment completely restored ventilation in mdx mice during normoxia and significantly increased mdx diaphragm force- and power-generating capacity. The number of centrally nucleated muscle fibres and the areal density of infiltrates and collagen content were significantly increased in mdx diaphragm; all indices were unaffected by drug co-treatment. The abundance of myosin heavy chain (MyHC) type IIx fibres was significantly decreased in mdx diaphragm; drug co-treatment preserved MyHC type IIx complement in mdx muscle. Drug co-treatment increased the cross-sectional area of MyHC type I and IIx fibres in mdx diaphragm. The cytokines IL-1β, IL-6, KC/GRO and TNF-α were significantly increased in mdx diaphragm compared with WT. Drug co-treatment significantly decreased IL-1β and increased IL-10 in mdx diaphragm. Drug co-treatment had no significant effect on WT diaphragm muscle structure, cytokine concentrations or function. Recovery of breathing and diaphragm force in mdx mice was impressive in our studies, with implication for human dystrophinopathies.

Role of GABAA Receptors of Parafacial Respiratory Group in Control of Respiration in Rats

The role of GABAergic inhibition in the regulation of activity of the parafacial respiratory group was studied on narcotized mature rats. Microinjections of GABA_A agonist muscimol into the parafacial respiratory group inhibited external respiration and bioelectrical activity of the diaphragmatic muscle resulting in diminished tidal volume and decreased respiration rate accompanied by prolonged inspiration, expiration, and intervals between the inspiratory bursts in the phrenic electromyogram. In contrast, microinjections of GABA_A antagonist bicuculline into this group stimulated respiration and markedly increased its volumetric parameters. In addition, blockade of GABA_A receptors affected the expiratory phase and interburst intervals in the phrenic electromyogram, but produced no effect on respiration rate. These findings attested to contribution of GABA_A-mediated inhibition into the performance of parafacial respiratory group. The study revealed different roles of GABA_A receptors in modulation of the mechanisms of respiration rate control in mature rats and formation of inspiratory motor outputs originating from the parafacial respiratory group.

Degrees of Diaphragma Sellae Descent during Transsphenoidal Pituitary Adenoma Resection: Predictive Factors and Effect on Outcome

This study is aimed to classify degrees of diaphragma sellae (DS) descent into sella turcica according to the surgical field block caused by the descent and to construct predictive imaging criteria for the degree of descent, and in addition, to determine whether there is any correlation between the degree of DS descent and the operative outcome (in the form of cerebrospinal fluid leak and/or presence of residual tumor). Totally, 72 patients were enrolled in our study. Their clinical and radiological data as well as the high definition videos of operations were retrospectively reviewed. The degree of DS descent during the operation was classified into five degrees according to surgical field block caused by the descent. We investigated the correlation between these five degrees and the clinical findings, radiological findings as well as the surgical outcomes. We found that the most important determining factors of DS descent degree were the volume and the height of the tumor portion above diaphragma opening. On the other hand, the total tumor volume, the maximum tumor height and the morphological pattern according to Wilson's system (modified from Hardy) had no statistically significant correlation with DS degree of descent. Presence of residual tumor on postoperative magnetic resonance images was significantly correlated with Wilson's classification and with supradiaphragmatic tumor height. On the other hand, cerebrospinal fluid leak showed no statistically significant difference between variable degrees of DS descent. Volumetric data of the tumor portion above the diaphragma opening are more important than morphological data for prediction of surgical field block caused by descended DS. While DS prolapse significantly increases the difficulty of the operative procedure, residual tumor presence is mainly dependent on morphological classification, especially cavernous sinus invasion.

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.

In patients with unilateral pleural effusion, restricted lung inflation is the principal predictor of increased dyspnoea

BACKGROUND AND OBJECTIVE

The mechanism of dyspnoea associated with pleural effusion is uncertain. A cohort of patients requiring thoracoscopy for unilateral exudative effusion were investigated for associations between dyspnoea and suggested predictors: impaired ipsilateral diaphragm movement, effusion volume and restricted lung inflation.

METHODS

Baseline Dyspnoea Index, respiratory function, and ultrasound assessment of ipsilateral diaphragm movement were assessed prior to thoracoscopy, when effusion volume was measured. Transitional Dyspnoea Index (change from baseline) was assessed 4 and 8 weeks after thoracoscopy. Pearson product moment assessed bivariate correlations and a general linear model examined how well total lung capacity (measuring restricted lung inflation), effusion volume and impaired diaphragm movement predicted Baseline Dyspnoea Index. Un-paired t tests compared the groups with normal and impaired diaphragm movement.

RESULTS

19 patients were studied (14 malignant etiology). Total lung capacity was associated with Baseline Dyspnoea Index (r = 0.68, P = 0.003). Effusion volume (r = -0.138, P = 0.60) and diaphragm movement (P = 0.09) were not associated with Baseline Dyspnoea Index. Effusion volume was larger with impaired diaphragm movement compared to normal diaphragm movement (2.16 ±SD 0.95 vs.1.16 ±0.92 L, P = 0.009). Total lung capacity was lower with impaired diaphragm movement compared to normal diaphragm movement (65.4 ±10.3 vs 78.2 ±8.6% predicted, P = 0.011). The optimal general linear model to predict Baseline Dyspnoea Index used total lung capacity alone (adjusted R2 = 0.42, P = 0.003). In nine participants with controlled effusion, baseline effusion volume (r = 0.775, P = 0.014) and total lung capacity (r = -0.690, P = 0.040) were associated with Transitional Dyspnoea Index.

CONCLUSIONS

Restricted lung inflation was the principal predictor of increased dyspnoea prior to thoracoscopic drainage of effusion, with no independent additional association with either effusion volume or impaired ipsilateral diaphragm movement. Restricted lung inflation may be an important determinant of the dyspnoea associated with pleural effusion.

A 63-Year-Old Man Presents With Slowly Progressive Dyspnea on Exertion and Lower Extremity Muscle Weakness

CASE PRESENTATION

A 63-year-old man was referred for slowly progressive dyspnea on exertion that had developed over 7 years. Dyspnea was initially only present during high-intensity physical activity, but was now present while walking rapidly on a flat surface. Symptoms were accentuated while supine and when bending forward. He reported respiratory difficulties when submerged in water and a recent onset of slight symmetric lower limb weakness that was only apparent during strenuous physical activity. He also had OSA, which was adequately controlled with continuous positive airway pressure therapy. Neurologic and rheumatologic histories were otherwise unremarkable. He denied any impact accidents or trauma to the cervical spine and prior neck or thoracic surgeries.

Anterior and posterior diaphragm kinesio taping for intractable hiccups after ischemic stroke: A case report

RATIONALE

Pathophysiologic mechanisms of the central nervous system, such as stroke, can be associated with intractable hiccups. Intractable hiccups can be associated with potentially fatal consequences, thus requiring safe management in an inpatient rehabilitation facility (IRF) setting with a multidisciplinary team approach to optimize mobility and feeding.

PATIENT CONCERNS

A 49-year-old male presented to the emergency department with complaints of vomiting and dizziness.

DIAGNOSES

Head computed tomography revealed moderate acute inferior cerebellar infarct in the territory of the posterior inferior cerebellar artery. He required a percutaneous endoscopic gastrostomy tube for feeding and developed severe intractable hiccups which he rated 7/10 on the hiccup assessment instrument (HAI) on IRF admission. Functional independence measure (FIM) score for transfers was 2 (maximum assist), walking was 1 (total assist), stairs were not attempted on IRF admit due to safety concerns, and feeding (eating) was 1 (total assist).

INTERVENTIONS

Anterior and posterior diaphragm kinesio taping was applied on day 6 of IRF physical therapy in an attempt to inhibit diaphragm spasm and intractable hiccups given that pharmacologic interventions had not been effective up to that point (Table 3).

OUTCOMES

The HAI decreased from 7/10 on day 6 of IRF physical therapy to 0/10 on day 8. The taping was reapplied every 3 to 5 days. On IRF day 9, his diet was advanced to a regular consistency with extra moisture and thin liquids. On day 21, hiccup severity remained 0/10 on the HAI, while FIM score for transfers was 4 (minimal assist), walking was 4 (minimal assist), stairs was 4 (minimal assist), and feeding (eating) was 7 (independent).

LESSONS

Diaphragm kinesio taping is a very effective treatment at reducing hiccup severity in a patient after ischemic stroke, while at the same time reducing burden of care for caregivers per FIM score improvement and improving diet to that of regular consistency with extra moisture and thin liquids.

Prolonged mechanical ventilation worsens sepsis-induced diaphragmatic dysfunction in the rat

Background

Short-term mechanical ventilation (MV) protects against sepsis-induced diaphragmatic dysfunction. Prolonged MV induces diaphragmatic dysfunction in non-septic animals, but few reports describe the effects of prolonged MV in sepsis. We hypothesized that prolonged MV is not protective but worsens the diaphragmatic dysfunction induced by a mild sepsis, because MV and sepsis share key signaling mechanisms, such as cytokine upregulation.

Method

We studied the impact of prolonged MV (12 h) in four groups (n = 8) of male Wistar rats: 1) endotoxemia induced by intraperitoneal injection of Escherichia coli lipopolysaccharide, 2) MV without endotoxemia, 3) combination of endotoxemia and MV and 4) sham control. Diaphragm mechanical performance, pro-inflammatory cytokine concentrations (Tumor Necrosis Factor-α, Interleukin-1β, Interleukin-6) in plasma were measured.

Results

Prolonged MV and sepsis independtly reduced maximum diaphragm force (-27%, P = 0.003; -37%, P<0.001; respectively). MV and sepsis acted additively to further decrease diaphragm force (-62%, P<0.001). Similar results were observed for diaphragm kinetics (maximum lengthening velocity -47%, P<0.001). Sepsis and MV reduced diaphragm cross sectional area of type I and IIx fibers, which was further increased by the combination of sepsis and MV (all P<0.05). Sepsis and MV were individually associated with the presence of a robust perimysial inflammatory infiltrate, which was more marked when sepsis and MV were both present (all P<0.05). Sepsis and, to a lesser extent, MV increased proinflammatory cytokine production in plasma and diaphragm (all P<0.05); proinflammatory cytokine expression in plasma was increased further by the combination of sepsis and MV (all P<0.05). Maximum diaphragm force correlated negatively with plasma and diaphragmatic cytokine production (all p<0.05).

Conclusions

Prolonged (12 h) MV exacerbated sepsis-induced decrease in diaphragm performance. Systemic and diaphragmatic overproduction of pro-inflammatory cytokines may contribute to diaphragm weakness.

Glottic patency during noninvasive ventilation in patients with chronic obstructive pulmonary disease

BACKGROUND

Non-invasive ventilation (NIV) provides ventilatory support for patients with respiratory failure. However, the glottis can act as a closing valve, limiting effectiveness of NIV. This study investigates the patency of the glottis during NIV in patients with acute exacerbation of Chronic Obstructive Pulmonary Disease (COPD).

METHODS

Electrical activity of the diaphragm, flow, pressure and videolaryngoscopy were acquired. NIV was randomly applied in pressure support (PSV) and neurally adjusted ventilatory assist (NAVA) mode with two levels of support. The angle formed by the vocal cords represented glottis patency.

RESULTS

Eight COPD patients with acute exacerbation requiring NIV were included. No differences were found in median glottis angle during inspiration or peak inspiratory effort between PSV and NAVA at low and high support levels.

CONCLUSIONS

The present study showed that glottis patency during inspiration in patients with an acute exacerbation of COPD is not affected by mode (PSV or NAVA) or level of assist (5 or 15 cm H₂O) during NIV.

Ultrasound-assessed diaphragmatic impairment is a predictor of outcomes in patients with acute exacerbation of chronic obstructive pulmonary disease undergoing noninvasive ventilation

BACKGROUND

Ultrasound (US) evaluation of diaphragmatic dysfunction (DD) has proved to be a reliable technique in critical care. In this single-center prospective study, we investigated the impact of US-assessed DD on noninvasive ventilation (NIV) failure in patients with acute exacerbations of chronic obstructive pulmonary disease (AECOPD) and its correlation with the transdiaphragmatic pressure assessed using the invasive sniff maneuver (Pdi sniff).

METHODS

A population of 75 consecutive patients with AECOPD with hypercapnic acidosis admitted to our respiratory intensive care unit (RICU) were enrolled. Change in diaphragm thickness (ΔTdi) < 20% during tidal volume was the predefined cutoff for identifying DD+/- status. Correlations between ΔTdi < 20% NIV failure and other clinical outcomes were investigated. Correlation between ΔTdi and Pdi sniff values was analyzed in a subset of ten patients.

RESULTS

DD+ patients had a higher risk for NIV failure than DD- patients (risk ratio, 4.4; p <  0.001), and this finding was significantly associated with higher RICU, in-hospital, and 90-day mortality rates; longer mechanical ventilation duration; higher tracheostomy rate; and longer RICU stay. Huge increases in NIV failure (HR, 6.2; p < 0.0001) and 90-day mortality (HR, 4.7; p = 0.008) in DD+ patients were found by Kaplan-Meier analysis. ΔTdi highly correlated with Pdi sniff (Pearson's r = 0.81; p = 0.004). ΔTdi < 20% showed better accuracy in predicting NIV failure than baseline pH value and early change in both arterial blood pH and partial pressure of carbon dioxide following NIV start (AUCs 0.84 to DTdi < 20%, 0.51 to pH value at baseline, 0.56 to early change in arterial blood pH following NIV start, and 0.54 to early change in partical pressure of carbon dioxide following NIV start, respectively; p < 0.0001).

CONCLUSIONS

Early and noninvasive US assessment of DD during severe AECOPD is reliable and accurate in identifying patients at major risk for NIV failure and worse prognosis.

Comparison of clinical utility between diaphragm excursion and thickening change using ultrasonography to predict extubation success

BACKGROUND/AIMS

Both diaphragmatic excursion and change in muscle thickening are measured using ultrasonography (US) to assess diaphragm function and mechanical ventilation weaning outcomes. However, which parameter can better predict successful extubation remains to be determined. The aim of this study was to compare the clinical utility of these two diaphragmatic parameters to predict extubation success.

METHODS

This study included patients subjected to extubation trial in the medical or surgical intensive care unit of a university-affiliated hospital from May 2015 through February 2016. Diaphragm excursion and percent of thickening change (Δtdi%) were measured using US within 24 hours before extubation.

RESULTS

Sixty patients were included, and 78.3% (47/60) of these patients were successfully extubated, whereas 21.7% (13/60) were not. The median degree of excursion was greater in patients with extubation success than in those with extubation failure (1.65 cm vs. 0.8 cm, p < 0.001). Patients with extubation success had a greater Δtdi% than those with extubation failure (42.1% vs. 22.5%, p = 0.03). The areas under the receiver operating curve for excursion and Δtdi% were 0.836 (95% confidence interval [CI], 0.717 to 0.919) and 0.698 (95% CI, 0.566 to 0.810), respectively (p = 0.017).

CONCLUSIONS

Diaphragm excursion seems more accurate than a change in the diaphragm thickness to predict extubation success.

Impact of chronic exposure to the pesticide chlorpyrifos on respiratory parameters and sleep apnea in juvenile and adult rats

The widely used organophosphorus pesticide chlorpyrifos (CPF) is often detected in food. CPF inhibits acetylcholinesterase and can modify muscle contractility and respiratory patterns. We studied the effects of chronic exposure to CPF on respiratory parameters and diaphragm contractility in 21- and 60-days old rats. Pregnant rats were exposed to oral CPF (1 or 5 mg/ kg /day: CPF-1 or CPF-5 groups vs vehicle: controls) from gestation onset up to weaning of the pups that were individually gavaged (CPF or vehicle) thereafter. Two developmental time points were studied: weaning (day 21) and adulthood (day 60). Whole-body plethysmography was used to score breathing patterns and apnea index during sleep. Then, diaphragm strips were dissected for the assessment of contractility and acetylcholinesterase activity. Results showed that the sleep apnea index was higher in CPF-exposed rats than in controls. In adult rats, the expiratory time and tidal volume were higher in CPF-exposed animals than in controls. At both ages, the diaphragm’s amplitude of contraction and fatigability index were higher in the CPF-5 group, due to lower acetylcholinesterase activity. We conclude that chronic exposure to CPF is associated with higher sleep apnea index and diaphragm contractility, and modifies respiratory patterns in sleeping juvenile and adult rats.

Diaphragm Excursion-Time Index: A New Parameter Using Ultrasonography to Predict Extubation Outcome

BACKGROUND

The diaphragmatic response to increased mechanical load following withdrawal of mechanical ventilation is critical in determining the outcome of extubation. Using ultrasonography, we aimed to evaluate the performance of the excursion-time (E-T) index-a product of diaphragm excursion and inspiratory time, to predict the outcome of extubation.

METHODS

Right hemidiaphragm excursion, inspiratory time, and E-T index were measured by ultrasonography during mechanical ventilation: (1) on assist-control (A/C) mode during consistent patient-triggered ventilation, (2) following 30 min during a spontaneous breathing trial (SBT), and (3) between 4 and 24 h following extubation. These measurements were correlated with the outcome of extubation. Patients in the "failure" group required reintubation or noninvasive ventilation within 48 h of extubation.

RESULTS

Of the 73 patients studied, 20 patients failed extubation. During SBT, diaphragm excursion was 1.65 ± 0.82 and 2.1 ± 0.9 cm (P = .06), inspiratory time was 0.89 ± 0.30 and 1.11 ± 0.39 s (P = .03), and the E-T index was 1.64 ± 1.19 and 2.42 ± 1.55 cm-s (P < .03) in the "failure" and "success" groups, respectively. The mean change in E-T index between A/C and SBT was -3.9 ± 57.8% in the failure group and 59.4 ± 74.6% in the success group (P < .01). A decrease in diaphragmatic E-T index less than 3.8% between A/C and SBT had a sensitivity of 79.2% and a specificity of 75%, to predict successful extubation.

CONCLUSIONS

Diaphragm E-T index measured during SBT may help predict the outcome of extubation. Maintenance or increase in diaphragm E-T index between A/C and SBT increases the likelihood of successful extubation.

A Latent Propriospinal Network Can Restore Diaphragm Function after High Cervical Spinal Cord Injury

Spinal cord injury (SCI) above cervical level 4 disrupts descending axons from the medulla that innervate phrenic motor neurons, causing permanent paralysis of the diaphragm. Using an ex vivo preparation in neonatal mice, we have identified an excitatory spinal network that can direct phrenic motor bursting in the absence of medullary input. After complete cervical SCI, blockade of fast inhibitory synaptic transmission caused spontaneous, bilaterally coordinated phrenic bursting. Here, spinal cord glutamatergic neurons were both sufficient and necessary for the induction of phrenic bursts. Direct stimulation of phrenic motor neurons was insufficient to evoke burst activity. Transection and pharmacological manipulations showed that this spinal network acts independently of medullary circuits that normally generate inspiration, suggesting a distinct non-respiratory function. We further show that this "latent" network can be harnessed to restore diaphragm function after high cervical SCI in adult mice and rats.

Evaluation of diaphragmatic function in mechanically ventilated children: An ultrasound study

Background

The recovery of diaphragmatic function is vital for successful extubation from mechanical ventilation. Recent studies have detected diaphragm atrophy in ventilated adults by using ultrasound, but no similar report has been conducted in children. In the current study, we hypothesized that mechanically ventilated children may also develop diaphragm atrophy and diaphragmatic dysfunction.

Materials and methods

Children who were admitted to the pediatric intensive care unit and were newly intubated for mechanical ventilation were enrolled into this prospective case–control study. Diaphragm ultrasound assessments were performed daily to evaluate diaphragmatic function in the enrolled children until their discharge from the pediatric intensive care unit. Diaphragm thickness and the diaphragmatic thickening fraction (DTF) were measured through these assessments.

Results

A total of 31 patients were enrolled, and overall, 1389 ultrasound assessments were performed. Immediately after intubation, the initial diaphragm thickness and DTF were measured to be 1.94 ± 0.44 mm and 25.85% ± 3.29%, respectively. In the first 24 hours of mechanical ventilation, diaphragm thickness and the DTF decreased substantially and decreased gradually thereafter. After extubation, the DTF was significantly different between the successful and failed extubation groups (P < 0.001), and a DTF value of <17% was associated with extubation failure.

Conclusions

Diaphragm ultrasound is a noninvasive method for measuring diaphragmatic function in mechanically ventilated children. In this study, significant diaphragm atrophy and a decreased DTF were observed within 24 hours of mechanical ventilation. The recovery of diaphragm thickness and the DTF may be a potential predictor of successful extubation from mechanical ventilation.

The predictive value of serial changes in diaphragm function during the spontaneous breathing trial for weaning outcome: a study protocol

INTRODUCTION

There is a variety of tools being used in clinical practice for the prediction of weaning success from mechanical ventilation. However, their diagnostic performances are less than satisfactory. The purpose of this study is to investigate the value of serial changes in diaphragm function measured by ultrasound during the spontaneous breathing trial (SBT) as a weaning predictor.

METHODS AND ANALYSIS

This is a prospective observational study conducted in a 10-bed medical emergency intensive care unit (EICU) in a university-affiliated hospital. The study will be performed from November 2016 to December 2017. All patients in the EICU who are expected to have mechanical ventilation for more than 48 hours through endotracheal tube are potentially eligible for this study. Patients will be included if they fulfil the criteria for SBT. All enrolled patients will be ventilated with an Evita-4 by using volume assist control mode prior to SBT. Positive end-expiratory pressure (PEEP) will be set to 5 cmH₂O and fractional inspired oxygen (FiO₂) will be set to a value below 0.5 that guarantees oxygen saturation by pulse oximetry (SpO₂) greater than 90%. Enrolled patients will undergo SBT for 2 hours in semirecumbent position. During the SBT, the patients will breathe through the ventilator circuit by using flow triggering (2 L/min) with automatic tube compensation of 100% and 5 cmH₂O PEEP. The FiO₂ will be set to the same value as used before SBT. If the patients fail to tolerate the SBT, the trial will be discontinued immediately and the ventilation mode will be switched to that used before the trial. Patients who pass the 2-hour SBT will be extubated. Right diaphragm excursion and bilateral diaphragm thickening fraction will be measured by ultrasonography during spontaneous breathing. Images will be obtained immediately prior to the SBT, and at 5, 30, 60, 90 and 120 min after the initiation of SBT. Rapid shallow breathing index will be simultaneously calculated at the bedside by a respiratory nurse.

ETHICS AND DISSEMINATION

The study protocol is approved by the ethics committee of Sir Run Run Shaw Hospital, an affiliate of Zhejiang University, Medical College. The results will be published in a peer-reviewed journal and shared with the worldwide medical community.

TRIAL REGISTRATION NUMBER

ISRCTN42917473; Pre-results.

Monitoring the electric activity of the diaphragm during noninvasive positive pressure ventilation: a case report

BACKGROUND

In patients with post-extubation respiratory distress, delayed reintubation may worsen clinical outcomes. Objective measures of extubation failure at the bedside are lacking, therefore clinical parameters are currently used to guide the need of reintubation. Electrical activity of the diaphragm (EAdi) provides clinicians with valuable, objective information about respiratory drive and could be used to monitor respiratory effort.

CASE PRESENTATION

We describe the case of a patient with Chronic Obstructive Pulmonary Disease (COPD), from whom we recorded EAdi during four different ventilatory conditions: 1) invasive mechanical ventilation, 2) spontaneous breathing trial (SBT), 3) unassisted spontaneous breathing, and 4) Noninvasive Positive Pressure Ventilation (NPPV). The patient had been intubated due to an exacerbation of COPD, and after four days of mechanical ventilation, she passed the SBT and was extubated. Clinical signs of respiratory distress were present immediately after extubation, and EAdi increased compared to values obtained during mechanical ventilation. As we started NPPV, EAdi decreased substantially, indicating muscle unloading promoted by NPPV, and we used the EAdi signal to monitor respiratory effort during NPPV. Over the next three days, she was on NPPV for most of the time, with short periods of spontaneous breathing. EAdi remained considerably lower during NPPV than during spontaneous breathing, until the third day, when the difference was no longer clinically significant. She was then weaned from NPPV and discharged from the ICU a few days later.

CONCLUSION

EAdi monitoring during NPPV provides an objective parameter of respiratory drive and respiratory muscle unloading and may be a useful tool to guide post-extubation ventilatory support. Clinical studies with continuous EAdi monitoring are necessary to clarify the meaning of its absolute values and changes over time.

The advantage of early plication in children diagnosed with diaphragm paresis

BACKGROUND

In this single-center study, we sought to determine the frequency of phrenic nerve injury leading to diaphragm paresis (DP) in children following open cardiac surgery over the last 10 years, and to identify possible variables that predict the need for plication and associated clinical outcomes.

METHODS

Patients diagnosed with DP were identified from departmental databases and a review of clinical diaphragm ultrasound images. A cohort was analyzed for predictors of diaphragm plication and associations with clinical outcomes. Cumulative proportion graphs modeled the association between plication and length of stay.

RESULTS

DP was diagnosed in 161 of 6448 patients (2.5%) seen between January 2002 and December 2012. All diagnoses but 1 were confirmed by ultrasound. Plication of the diaphragm was performed in 30 patients (19%); compared with patients who did not undergo plication, these patients were younger (median age, 10 days vs 138 days; P < .001), more likely to have undergone deep hypothermic circulatory arrest (47% vs 18%; P = .005), had a longer duration of positive pressure ventilation (median, 15 days vs 7 days; P < .001), and had longer lengths of stay in both the intensive care unit (median, 23 days vs 8 days; P < .0001) and the hospital (median, 37 days vs 15 days; P < .0001). Early plication was associated with reduction in all intervals of care.

CONCLUSIONS

Early plication should be considered for patients with diaphragm paresis requiring prolonged respiratory support after cardiac bypass surgery. Longer follow-up evaluation is required to better define the long-term implications of plication.

Diaphragmatic dysfunction in SEPN1-related myopathy

SEPN1-related myopathy (SEPN1-RM) is characterized by predominant axial muscle weakness, early scoliosis, rigid spine and severe respiratory insufficiency. The aim of the study was to characterize the mechanisms of respiratory dysfunction in SEPN1-RM patients. Breathing pattern and respiratory muscle strength were measured by means of esophageal (Pes) and gastric (Pgas) pressures. Seven patients aged 7-55 years (1 adult) at first respiratory muscle test were studied. Five patients were treated by nocturnal noninvasive ventilation (NIV)  ≥ 4 months. Mean ΔPes was within normality during tidal breathing, but the ΔPgas/ΔPes index indicated an increased contribution of the rib cage and expiratory muscles, as compared to the diaphragm, in the pediatric patients and bilateral diaphragmatic paralysis in the adult patient. Forced vital capacity (FVC) was reduced in all patients (52 ± 19%pr) with mean FVC seated-supine drop of 24 ± 7%. Global inspiratory muscle and diaphragmatic strengths were moderately reduced in 2 patients, highly reduced in 4 patients and severely reduced in the adult patient. Expiratory muscle strength was moderately reduced in 6 patients and severely reduced in the adult patient. FVC and respiratory muscle strength remained stable in 2 patients treated by nocturnal NIV within a 3-year follow-up. This study confirms that diaphragmatic dysfunction is a characteristic feature of SEPN1-RM and NIV may stabilize the decline in respiratory muscle strength.

Drainage of pleural effusion improves diaphragmatic function in mechanically ventilated patients

BACKGROUND

Pleural effusion adversely affects the pressuregenerating capacity of the diaphragm. It uncouples the lung and chest wall, which may result in diaphragmatic dysfunction. Information on the effects of effusion drainage on diaphragmatic function is limited, but several studies report relief of dyspnoea after drainage, which was attributed to improved diaphragmatic mechanics, even if this issue was never formally addressed.

OBJECTIVE

To investigate the effect of drainage of unilateral pleural effusion on diaphragmatic function.

DESIGN, SETTING AND PATIENTS

In a prospective twostep protocol (at baseline and after drainage of effusion), we conducted a spontaneous breathing trial in fourteen critically ill, mechanically ventilated patients undergoing pressure support ventilation.

MAIN OUTCOME MEASURES

We used ultrasonography of the ipsilateral hemidiaphragm to evaluate and record respiratory displacement and thickening during tidal and maximal breathing efforts. We recorded and analysed airway pressures, respiratory system compliance, vital capacity, indices of respiratory effort and arterial blood gases.

RESULTS

After drainage of the effusion, the respiratory rate decreased and tidal volume increased, but haemodynamic parameters were unaffected and oxygenation levels showed a non-significant increase. Drainage was associated with significant decreases in indices of respiratory drive and the maximal pressure generated by the respiratory muscles, as well as an increased compliance of the respiratory system. Diaphragmatic displacement and thickening significantly increased after drainage. We found there was a significant correlation between the volume of the effusion drained and the increase in tidal diaphragmatic thickening.

CONCLUSIONS

Drainage of a unilateral pleural effusion during weaning from mechanical ventilation improves diaphragmatic contractile activity and respiratory system performance.

Superoxide dismutase/catalase mimetic EUK-134 prevents diaphragm muscle weakness in monocrotalin-induced pulmonary hypertension

Patients with pulmonary hypertension (PH) suffer from inspiratory insufficiency, which has been associated with intrinsic contractile dysfunction in diaphragm muscle. Here, we examined the role of redox stress in PH-induced diaphragm weakness by using the novel antioxidant, EUK-134. Male Wistar rats were randomly divided into control (CNT), CNT + EUK-134 (CNT + EUK), monocrotaline-induced PH (PH), and PH + EUK groups. PH was induced by a single intraperitoneal injection of monocrotaline (60 mg/kg body weight). EUK-134 (3 mg/kg body weight/day), a cell permeable mimetic of superoxide dismutase (SOD) and catalase, was daily intraperitoneally administered starting one day after induction of PH. After four weeks, diaphragm muscles were excised for mechanical and biochemical analyses. There was a decrease in specific tetanic force in diaphragm bundles from the PH group, which was accompanied by increases in: protein expression of NADPH oxidase 2/gp91phox, SOD2, and catalase; 3-nitrotyrosine content and aggregation of actin; glutathione oxidation. Treatment with EUK-134 prevented the force decrease and the actin modifications in PH diaphragm bundles. These data show that redox stress plays a pivotal role in PH-induced diaphragm weakness. Thus, antioxidant treatment can be a promising strategy for PH patients with inspiratory failure.

Diaphragmatic breathing during virtual reality exposure therapy for aviophobia: functional coping strategy or avoidance behavior? a pilot study

BACKGROUND

Although there is solid evidence for the efficacy of in vivo and virtual reality (VR) exposure therapy for a specific phobia, there is a significant debate over whether techniques promoting distraction or relaxation have impairing or enhancing effects on treatment outcome. In the present pilot study, we investigated the effect of diaphragmatic breathing (DB) as a relaxation technique during VR exposure treatment.

METHOD

Twenty-nine patients with aviophobia were randomly assigned to VR exposure treatment either with or without diaphragmatic breathing (six cycles per minute). Subjective fear ratings, heart rate and skin conductance were assessed as indicators of fear during both the exposure and the test session one week later.

RESULTS

The group that experienced VR exposure combined with diaphragmatic breathing showed a higher tendency to effectively overcome the fear of flying. Psychophysiological measures of fear decreased and self-efficacy increased in both groups with no significant difference between the groups.

CONCLUSIONS

Our findings indicate that diaphragmatic breathing during VR exposure does not interfere with the treatment outcome and may even enhance treatment effects of VR exposure therapy for aviophobic patients.

TRIAL REGISTRATION

Retrospectively registered. ClinicalTrials.gov NCT02990208 . Registered 07 December 2016.

Chronic TrkB agonist treatment in old age does not mitigate diaphragm neuromuscular dysfunction

Previously, we found that brain-derived neurotrophic factor (BDNF) signaling through the high-affinity tropomyosin-related kinase receptor subtype B (TrkB) enhances neuromuscular transmission in the diaphragm muscle. However, there is an age-related loss of this effect of BDNF/TrkB signaling that may contribute to diaphragm muscle sarcopenia (atrophy and force loss). We hypothesized that chronic treatment with 7,8-dihydroxyflavone (7,8-DHF), a small molecule BDNF analog and TrkB agonist, will mitigate age-related diaphragm neuromuscular transmission failure and sarcopenia in old mice. Adult male TrkBF616A mice (n = 32) were randomized to the following 6-month treatment groups: vehicle-control, 7,8-DHF, and 7,8-DHF and 1NMPP1 (an inhibitor of TrkB kinase activity in TrkBF616A mice) cotreatment, beginning at 18 months of age. At 24 months of age, diaphragm neuromuscular transmission failure, muscle-specific force, and fiber cross-sectional areas were compared across treatment groups. The results did not support our hypothesis in that chronic 7,8-DHF treatment did not improve diaphragm neuromuscular transmission or mitigate diaphragm muscle sarcopenia. Taken together, these results do not exclude a role for BDNF/TrkB signaling in aging-related changes in the diaphragm muscle, but they do not support the use of 7,8-DHF as a therapeutic agent to mitigate age-related neuromuscular dysfunction.

Esophagogastric Junction Morphology and Distal Esophageal Acid Exposure

BACKGROUND

The Chicago classification has recently added a morphological subclassification for the esophagogastric junction (EGJ). Our aim was to assess the distal esophageal acid exposure in patients with this new Chicago EGJ-type IIIa and IIIb classification.

STUDY DESIGN

From a prospectively collected high-resolution manometry (HRM) database, we identified patients who underwent 24-h pH study between October 2011 and June 2015 and were diagnosed with EGJ-type III based on HRM. Chicago EGJ-type III is defined as the inter-peak nadir pressure ≤gastric pressure and a lower esophageal sphincter (LES)-crural diaphragm (CD) separation >2 cm [IIIa-pressure inversion point (PIP) remains at CD level and IIIb-PIP remains at LES level]. We classified the patients into reflux group [DeMeester score >14.72 or Fraction time pH (<4) > 4.2 %] and non-reflux group based on 24-h pH study.

RESULTS

Fifty patients were identified that satisfied the study criteria, of which 37 patients (74 %) were EGJ-type IIIa. In those with EGJ-type IIIb, abdominal LES length (AL) in reflux group was significantly shorter than the non-reflux group (0.8 vs. 1.8, p < 0.05). EGJ-type IIIa patients showed significantly higher value for DeMeester score and Fraction time pH and more often had a positive pH study than EGJ-type IIIb patients (DeMeester score: 26.7 vs. 11.7, p < 0.05; Fraction time pH: 7.9 vs. 2.6, p < 0.05; positive pH study: 81.1 vs. 30.8 %, p < 0.001). Reflux was more common in LES-CD ≥ 3 cm than that in LES-CD < 3 cm (85 vs. 56.7 %, p < 0.05).

CONCLUSION

A subset of patients with >2-cm LES-CD separation (type IIIb) maintain a physiological intra-abdominal location of the EGJ and are less likely to have reflux. A LES-CD ≥ 3 cm seems to discern a hiatus hernia of clinical significance.

Electrically induced mechanomyograms reflect inspiratory muscle strength in young or elderly subjects

BACKGROUND

Respiratory muscle strength has been used as a tool for evaluating respiratory rehabilitation in chronic obstructive pulmonary disease. However, mouth pressure measurement evaluated by maximum expiratory mouth pressure (PEmax) or inspiratory mouth pressure (PImax) offers an indirect method for measuring respiratory muscle strength. We demonstrated the evaluation of diaphragm contractility using a mechanomyogram (MMG), which is the mechanical signal generated by the motion of the diaphragm induced by the electric stimulation of the phrenic nerve.

METHODS

Study participants were 21 young and 20 elderly subjects with no symptoms of respiratory disease. The elderly subjects were divided into non-smoker or smoker groups. The smoker group was defined as subjects having a Brinkman Index of greater than 300. We measured basic spirometric parameters, mouth pressure (PEmax, PImax), and diaphragmatic MMG.

RESULTS

Diaphragmatic MMG showed more clear contrast between young subjects and elderly non-smoker or smoker subjects than the conventional method for respiratory muscle contraction (PEmax, PImax). In addition, the diaphragmatic MMG strongly correlated with inspiratory muscle strength.

CONCLUSIONS

Diaphragmatic MMG may reflect diaphragmatic contractility more directly and sensitively than the conventional method.

BGP-15 Improves Aspects of the Dystrophic Pathology in mdx and dko Mice with Differing Efficacies in Heart and Skeletal Muscle

Duchenne muscular dystrophy is a severe and progressive striated muscle wasting disorder that leads to premature death from respiratory and/or cardiac failure. We have previously shown that treatment of young dystrophic mdx and dystrophin/utrophin null (dko) mice with BGP-15, a coinducer of heat shock protein 72, ameliorated the dystrophic pathology. We therefore tested the hypothesis that later-stage BGP-15 treatment would similarly benefit older mdx and dko mice when the dystrophic pathology was already well established. Later stage treatment of mdx or dko mice with BGP-15 did not improve maximal force of tibialis anterior (TA) muscles (in situ) or diaphragm muscle strips (in vitro). However, collagen deposition (fibrosis) was reduced in TA muscles of BGP-15-treated dko mice but unchanged in TA muscles of treated mdx mice and diaphragm of treated mdx and dko mice. We also examined whether BGP-15 treatment could ameliorate aspects of the cardiac pathology, and in young dko mice it reduced collagen deposition and improved both membrane integrity and systolic function. These results confirm BGP-15's ability to improve aspects of the dystrophic pathology but with differing efficacies in heart and skeletal muscles at different stages of the disease progression. These findings support a role for BGP-15 among a suite of pharmacological therapies for Duchenne muscular dystrophy and related disorders.

[Relation between ultrasound-measured diaphragm movement and partial pressure of carbon dioxide in blood from patients with acute hypercapnic respiratory failure after the start of noninvasive ventilation in an emergency department]

OBJECTIVES

To evaluate the correlation between variations in ultrasound-measured diaphragm movement and changes in the arterial partial pressure of carbon dioxide (PCO2) after the start of noninvasive ventilation (NIV).

MATERIAL AND METHODS

RDescriptive study of a prospective case series comprised of nonconsecutive patients aged 18 years or older with hypercapnic respiratory failure who were placed on NIV in an emergency department. We recorded clinical data, blood gas measurements, and ultrasound measurements of diaphragm movement.

RESULTS

Twenty-one patients with a mean (SD) age of 83 (13) years were studied; 11 (52.4%) were women. The mean (SD) range of diaphragm movement and PCO2 values at 4 moments were as follows: 1) at baseline: diaphragm movement, 13.90 (7.7) mm and PCO2, 71.75 (11.4) mm Hg; 2) after 15 minutes on NIV: diaphragm movement, 17.10 (9.1) mm; 3) at 1 hour: diaphragm movement, 22.40 (10.4) mm and PCO2, 63.45 (16.0) mm Hg; and 4) at 3 hours: diaphragm movement, 26.60 (19.5) mm and PCO2, 61.85 (13.0) mm Hg. We detected a statistically significant correlation between the difference in range of diaphragm movement at baseline and at 15 minutes and the decrease in PCO2 after 1 hour of NIV (r=-0.489, P=.035).

CONCLUSION

In patients with hypercapnic respiratory failure, the increase in range of diaphragm movement 15 minutes after starting NIV is associated with a decrease in PCO2 after 1 hour.

A Case of Spontaneous Rupture of the Diaphragm in a Young Pregnant Female Presenting with Hydropneumothorax

We present a case of spontaneous rupture of the diaphragm in a young pregnant female mimicking hydropneumothorax. She had a chest tube placed on admission without any improvement in her symptoms, which led to further imaging. Chest and abdomen CT after a barium swallow confirmed the clinical diagnosis. She had definitive surgical repair followed by an uneventful clinical recovery.

[Diaphragm disorders in adults]

Diaphragm disorders in adults. Diaphragm diseases, functional particularly, are little known and often underestimated by clinicians. Whether a fortuitous discovery on a chest x-ray showing an elevation of the hemidiaphragm or revealed by dyspnea, these abnormalities of the diaphragm require further investigations. The objective is to confirm the diagnosis, understanding the mechanism, to clarify the functional consequences and to consider treatment. Some dysfunctions may be temporary, contraindicating any emergency treatment apart from acute ruptures. Only symptomatic cases require a surgical treatment. The type of surgery depends on the cause and can range from simple repair of a diaphragmatic defect, diaphragm plication to restore tensioning and even phrenic pacing in very rare cases.

Is polysomnographic examination necessary for subjects with diaphragm pathologies?

OBJECTIVES

While respiratory distress is accepted as the only indication for diaphragmatic plication surgery, sleep disorders have been underestimated. In this study, we aimed to detect the sleep disorders that accompany diaphragm pathologies. Specifically, the association of obstructive sleep apnea syndrome with diaphragm eventration and diaphragm paralysis was evaluated.

METHODS

This study was performed in Süreyyapasa Chest Diseases and Thoracic Surgery Training and Research Hospital between 2014-2016. All patients had symptoms of obstructive sleep apnea (snoring and/or cessation of breath during sleep and/or daytime sleepiness) and underwent diaphragmatic plication via video-assisted mini-thoracotomy. Additionally, all patients underwent pre- and postoperative full-night polysomnography. Pre- and postoperative clinical findings, polysomnography results, Epworth sleepiness scale scores and pulmonary function test results were compared.

RESULTS

Twelve patients (7 males) with a mean age of 48 (range, 27-60) years and a mean body mass index of 25 (range, 20-30) kg/m2 were included in the study. Preoperative polysomnography showed obstructive sleep apnea syndrome in 9 of the 12 patients (75%), while 3 of the patients (25%) were regarded as normal. Postoperatively, patient complaints, apnea hypopnea indices, Epworth sleepiness scale scores and pulmonary function test results all demonstrated remarkable improvement.

CONCLUSION

All patients suffering from diaphragm pathologies with symptoms should undergo polysomnography, and patients diagnosed with obstructive sleep apnea syndrome should be operated on. In this way, long-term comorbidities of sleep disorders may be prevented.

Quantification of Diaphragm Mechanics in Pompe Disease Using Dynamic 3D MRI

BACKGROUND

Diaphragm weakness is the main reason for respiratory dysfunction in patients with Pompe disease, a progressive metabolic myopathy affecting respiratory and limb-girdle muscles. Since respiratory failure is the major cause of death among adult patients, early identification of respiratory muscle involvement is necessary to initiate treatment in time and possibly prevent irreversible damage. In this paper we investigate the suitability of dynamic MR imaging in combination with state-of-the-art image analysis methods to assess respiratory muscle weakness.

METHODS

The proposed methodology relies on image registration and lung surface extraction to quantify lung kinematics during breathing. This allows for the extraction of geometry and motion features of the lung that characterize the independent contribution of the diaphragm and the thoracic muscles to the respiratory cycle.

RESULTS

Results in 16 3D+t MRI scans (10 Pompe patients and 6 controls) of a slow expiratory maneuver show that kinematic analysis from dynamic 3D images reveals important additional information about diaphragm mechanics and respiratory muscle involvement when compared to conventional pulmonary function tests. Pompe patients with severely reduced pulmonary function showed severe diaphragm weakness presented by minimal motion of the diaphragm. In patients with moderately reduced pulmonary function, cranial displacement of posterior diaphragm parts was reduced and the diaphragm dome was oriented more horizontally at full inspiration compared to healthy controls.

CONCLUSION

Dynamic 3D MRI provides data for analyzing the contribution of both diaphragm and thoracic muscles independently. The proposed image analysis method has the potential to detect less severe diaphragm weakness and could thus be used to determine the optimal start of treatment in adult patients with Pompe disease in prospect of increased treatment response.

Inhibition of Src and forkhead box O1 signaling by induced pluripotent stem-cell therapy attenuates hyperoxia-augmented ventilator-induced diaphragm dysfunction

Mechanical ventilation (MV) with hyperoxia is required for providing life support to patients with acute lung injury (ALI). However, MV may cause diaphragm weakness through muscle injury and atrophy, an effect termed ventilator-induced diaphragm dysfunction (VIDD). Src protein tyrosine kinase and class O of forkhead box 1 (FoxO1) mediate acute inflammatory responses and muscle protein degradation induced by oxidative stress. Induced pluripotent stem cells (iPSCs) have been reported to improve hyperoxia-augmented ALI; however, the mechanisms regulating the interactions among VIDD, hyperoxia, and iPSCs are unclear. In this study, we hypothesized that iPSC therapy can ameliorate hyperoxia-augmented VIDD by suppressing the Src-FoxO1 pathway. Male C57BL/6 mice, either wild-type or Src-deficient, aged between 6 and 8 weeks were exposed to MV (6 or 10 mL/kg) with or without hyperoxia for 2-8 h after the administration of 5 × 10(7) cells/kg Oct4/Sox2/Parp1 mouse iPSCs or iPSC-derived conditioned medium (iPSC-CM). Nonventilated mice were used as controls. MV during hyperoxia aggravated VIDD, as demonstrated by the increases in Src activation, FoxO1 dephosphorylation, malondialdehyde, caspase-3, atrogin-1 and muscle ring finger-1 production, microtubule-associated protein light chain 3-II, disorganized myofibrils, disrupted mitochondria, autophagy, and myonuclear apoptosis; however, MV with hyperoxia reduced mitochondrial cytochrome C, diaphragm muscle fiber size, and contractility (P < 0.05). Hyperoxia-exacerbated VIDD was attenuated in Src-deficient mice and by iPSCs and iPSC-CM (P < 0.05). Our data indicate that iPSC therapy attenuates MV-induced diaphragmatic injury that occurs during hyperoxia-augmented VIDD by inhibiting the Src-FoxO1 signaling pathway.

[APPLICATION OF RECONSTRUCTIVE SURGICAL TECHNIQUES FOR THE PERIPHERAL NERVE TO INJURED PHRENIC NERVE TO RESTORE THE PARALYZED DIAPHRAGM]

Phrenic nerve injury often causes diaphragmatic dysfunction. Damage to the phrenic nerve may be caused by iatrogenic injury such as transection or crush during thoracic or neck surgery to treat bronchogenic, mediastinal, or neck tumors. Plication of the diaphragm is a procedure in which the flaccid hemidiaphragm is tautened by oversuturing it. Although it has been offered to patients with unilateral diaphragmatic paralysis who have severe dyspnea and other symptoms, the essential treatment should be restoration of the function to the paralyzed diaphragm. Established reconstructive techniques for peripheral nerves are indicated to treat some phrenic nerve injury cases. Muscle contraction and diaphragmatic function following nerve reconduction is recovered in many clinical cases, and favorable experimental results were seen in animal models. Reconstructive nerve procedures such as repair, graft, or transfer may be indicated in more cases of phrenic nerve injury to improve prognostic outcomes of surgery to treat locally advanced malignancies.

Diaphragmatic fatigue during inspiratory muscle loading in normoxia and hypoxia

INTRODUCTION

Diaphragmatic fatigue (DF) occurs during strenuous loading of respiratory muscles (e.g., heavy-intensity whole-body exercise, normocapnic hyperpnea, inspiratory resistive breathing). DF develops early on during normoxia, without further decline toward task failure; however, its progression during inspiratory muscle loading in during hypoxia remains unclear. Therefore, the present study used volume-corrected transdiaphragmatic pressures during supramaximal magnetic phrenic nerve stimulation (Pdi,twc) to investigate the effect of hypoxia on the progression of diaphragmatic fatigue during inspiratory muscle loading.

METHODS

Seventeen subjects completed two standardized rounds of inspiratory muscle loading (blinded, randomized) under the following conditions: (i) normoxia, and (ii) normobaric hypoxia (SpO2 80%), with Pdi,twc assessment every 45 s.

RESULTS

In fatiguers (i.e., Pdi,twc reduction >10%, n=10), biometric approximation during normoxia is best represented by Pdi,twc=4.06+0.83 exp(-0.19 × x), in contrast to Pdi,twc=4.38-(0.05 × x) during hypoxia.

CONCLUSION

Progression of diaphragmatic fatigue during inspiratory muscle loading assessed by Pdi,tw differs between normoxia and normobaric hypoxia: in the former, Pdi,tw follows an exponential decay, whereas during hypoxia, Pdi,tw follows a linear decline.