Ultrasound in the Assessment of Respiration

Paradoxical thinning of the diaphragm on ultrasound is a risk factor for requiring non-invasive ventilation in patients with neuromuscular diaphragmatic dysfunction

INTRODUCTION/AIMS

Point-of-care ultrasound of the diaphragm is highly sensitive and specific in the detection of neuromuscular diaphragmatic dysfunction. In some patients with neuromuscular diaphragmatic dysfunction, paradoxical thinning of the diaphragm during inspiration is observed on ultrasound; however, its frequency, electrodiagnostic associations, and prognostic significance remain uncertain.

METHODS

Medical records of patients presenting to two electrodiagnostic laboratories (Mayo Clinic, Rochester, Minnesota and University of Alberta, Edmonton, Alberta) from January 1, 2022 to December 31, 2022, for evaluation of suspected neuromuscular respiratory failure, were reviewed.

RESULTS

214 patients were referred and 19 patients excluded due to incomplete information. Of 195 patients (384 hemidiaphragms), 104 had phrenic neuropathy, 12 had myopathy, and 79 had no evidence of neuromuscular disease affecting the diaphragm. Paradoxical thinning occurred in 31 (27%) patients with neuromuscular diaphragmatic dysfunction and was unilateral in 30, the majority (83%) having normal contralateral ultrasound. Phrenic nerve conduction studies and diaphragm electromyography results did not distinguish patients with paradoxical thinning versus without. Most patients (71%) with paradoxical thinning required non-invasive ventilation (NIV), including 16 with unilateral paradoxical thinning. Paradoxical thinning and BMI ≥30 kg/m2 were risk factors for requiring NIV in multivariable logistic regression analysis, with odds ratios of 2.887 (95% CI:1.166, 7.151) and 2.561 (95% CI: 1.186, 5.532), respectively.

DISCUSSION

Paradoxical thinning of the diaphragm occurs in patients with prominent neuromuscular diaphragmatic dysfunction, most commonly from phrenic neuropathy, and is a significant risk factor for requiring NIV. Unilateral paradoxical thinning is sufficient for needing NIV. BMI ≥30 kg/m2 additionally increases risk of requiring NIV in patients with neuromuscular diaphragmatic dysfunction.

Changes in respiratory structure and function after traumatic cervical spinal cord injury: observations from spinal cord and brain

Respiratory difficulties and mortality following severe cervical spinal cord injury (CSCI) result primarily from malfunctions of respiratory pathways and the paralyzed diaphragm. Nonetheless, individuals with CSCI can experience partial recovery of respiratory function through respiratory neuroplasticity. For decades, researchers have revealed the potential mechanism of respiratory nerve plasticity after CSCI, and have made progress in tissue healing and functional recovery. While most existing studies on respiratory plasticity after spinal cord injuries have focused on the cervical spinal cord, there is a paucity of research on respiratory-related brain structures following such injuries. Given the interconnectedness of the spinal cord and the brain, traumatic changes to the former can also impact the latter. Consequently, are there other potential therapeutic targets to consider? This review introduces the anatomy and physiology of typical respiratory centers, explores alterations in respiratory function following spinal cord injuries, and delves into the structural foundations of modified respiratory function in patients with CSCI. Additionally, we propose that magnetic resonance neuroimaging holds promise in the study of respiratory function post-CSCI. By studying respiratory plasticity in the brain and spinal cord after CSCI, we hope to guide future clinical work.

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

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

Muscle ultrasound in hereditary muscle disease

In this review we summarise the key techniques of muscle ultrasound as they apply to hereditary muscle disease. We review the diagnostic utility of muscle ultrasound including its role in guiding electromyography and muscle biopsy sampling. We summarize the different patterns of sonographic muscle involvement in the major categories of genetic muscle disorders and discuss the limitations of the technique. We hope to encourage others to adopt ultrasound in their care for patients with hereditary muscle diseases.

MRI-assessed diaphragmatic function can predict frequent acute exacerbation of COPD: a prospective observational study based on telehealth-based monitoring system

BACKGROUND

Acute exacerbations of chronic obstructive pulmonary disease (AECOPD) have considerably high mortality and re-hospitalisation rate. Diaphragmatic dysfunction (DD) is common in COPD patients. However, whether diaphragmatic dysfunction is related to acute exacerbation is yet to be elucidated. This study aimed to evaluate the diaphragm function by magnetic resonance imaging (MRI) in COPD patients and assess whether the impact of DD may help predict AECOPD.

METHODS

20 healthy adult volunteers and 80 COPD patients were enrolled. The diaphragms function parameters were accessed by MRI. Patients were guided to start self-management by the Telehealth-based monitoring system following the enrolment. Events of acute exacerbation of COPD were recorded by the system and confirmed by healthcare providers. Binary univariate and multivariate logistic regression analyses were performed to investigate the factors associated with the frequency of AECOPD. Receiver operating characteristic (ROC) curves were further used to assess the value of prediction indexes.

RESULTS

Fifty-nine COPD patients completed a one-year follow-up based on the Telehealth-based monitoring system. The clinical outcomes showed that the diaphragm function parameters at the end of maximal breathing were lower in the COPD group than in the healthy control group (P < 0.05). ANOVA showed significant differences among Global Initiative for Chronic Obstructive Lung Disease (GOLD) stages for diaphragm function parameters, including chest wall motion, lung area, upper-lower diameter, and the diaphragm thickening fraction at the end of maximal breathing (P < 0.05). Moreover, significant differences in diaphragm function parameters were observed between patients with infrequent AECOPD (n = 28) and frequent AECOPD (n = 31) based on the frequency of AECOPD (P < 0.05). The diaphragm thickening fraction and the chest wall motion were associated with AECOPD after adjusting for age, sex, BMI, and lung functions, and the combination of predictions showed better accuracy in predicting the frequency of AECOPD.

CONCLUSIONS

In COPD patients, diaphragm function parameters correlate with the severity of airflow limitation. The diaphragm thickening fraction and the chest wall motion were associated with the frequency of AECOPD and can predict it.

A randomised controlled trial in patients undergoing arthroscopic shoulder surgery comparing interscalene block with either 10 ml or 20 ml levobupivacaine 0.25

The interscalene brachial plexus block is recommended for analgesia after shoulder surgery but it may cause hemidiaphragmatic dysfunction. We tested whether ipsilateral hemidiaphragmatic contraction was better after a smaller dose of local anaesthetic without impairing analgesic effect. We randomly allocated 48 adults to 10 ml or 20 ml levobupivacaine 0.25% before arthroscopic shoulder surgery. The primary outcome was hemidiaphragmatic paralysis, defined as inspiratory thickness < 1.2 times expiratory thickness, measured by ultrasound 4 h after block. Hemidiaphragmatic paralysis was recorded for 6/24 vs. 23/24 supine participants after 10 ml vs. 20 ml levobupivacaine 0.25%, respectively, and for 4/24 vs. 23/24 sitting participants, respectively, p < 0.001 for both. Pain scores after 10 ml injectate were not worse than after 20 ml injectate. Median (IQR [range]) morphine doses in the first 24 postoperative hours after 10 ml and 20 ml levobupivacaine 0.25% were 2 (0-6 [0-23]) mg vs. 1 (0-2 [0-11]) mg, respectively, p = 0.12. No participant had a complication after 10 ml interscalene levobupivacaine, whereas seven had complications after 20 ml levobupivacaine, p = 0.009. Hemidiaphragmatic function was better after 10 ml vs. 20 ml interscalene levobupivacaine 0.25% without impairing analgesia for 24 postoperative hours.

Assessments and Targeted Rehabilitation Therapies for Diaphragmatic Dysfunction in Patients with Chronic Obstructive Pulmonary Disease: A Narrative Review

Purpose

This review summarizes the characteristics, assessment methods, and targeted rehabilitation therapies of diaphragm dysfunction in patients with chronic obstructive pulmonary disease (COPD).

Methods

Extensive literature was searched in PubMed, the Cochrane Library, Web of Science, Chinese National Knowledge Infrastructure Database, Wanfang, and SinoMed.

Results

Under the influence of oxidative stress, inflammation, and other factors, the diaphragm function of patients with COPD changes in mobility, muscle strength, thickness, and thickening. In patients with COPD, diaphragm mobility can be assessed using ultrasound, X-ray fluoroscopy, and magnetic resonance imaging. Diaphragmatic strength can be measured by transdiaphragmatic pressure and maximal inspiratory pressure. Diaphragmatic thickness and thickening can be assessed using ultrasound. Rehabilitation therapies targeting the diaphragm include diaphragmatic breathing, diaphragm-related manual therapy, and phrenic nerve electrical stimulation. Diaphragmatic breathing is safe, simple, and not limited by places. Diaphragmatic manual therapies, which require patient cooperation and one-on-one operation by a professional therapist, are effective. Phrenic nerve electrical stimulation is suitable for patients with severe conditions. These therapies improve the diaphragmatic function, lung function, dyspnea, and exercise capacity of patients with COPD.

Conclusion

The diaphragmatic function is commonly assessed in terms of mobility, strength, thickness, and thickening. Diaphragmatic targeted rehabilitation therapies have proven to be efficient, which are recommended to be included in the pulmonary rehabilitation strategy for patients with COPD.

Ultrasonographic evaluation of diaphragm thickness and excursion in patients with cervical spinal cord injury

Objective: To evaluate the diaphragm thickness and excursion in patients with cervical spinal cord injury and reliability of diaphragmatic ultrasonography.Design: A Pilot Case-Control Study.Setting: China Rehabilitation Research Center (CRRC) /Beijing BO AI Hospital.Participants: Sixty participants with cervical spinal cord injury and sixty control participants were eligible for inclusion in this study.Interventions: Ultrasonographic evaluation of the diaphragm.Outcome Measures: All demographic data were evaluated. Diaphragm thickness, thickening ratio, and diaphragm excursions were assessed at the end of quiet tidal breathing and maximal inspiration. The reliability of inter- and intra-ultrasonography operators were evaluated.Results: Diaphragm thickness was significantly higher in patients with cervical spinal cord injury than the control group (P < 0.001). Diaphragmatic excursion of the right hemidiaphragm was significantly greater in patients with cervical spinal cord injury than the control group (P < 0.001) at the end of quiet tidal breathing. No difference was found in diaphragmatic excursion between two groups (P = 0.32) at the end of maximal inspiration. No significant difference was shown between two groups in thickening ratio. Intraclass correlation coefficients of inter-and intra-ultrasonography operators for the thickness and excursions of the diaphragm were greater than 0.93.Conclusion: Compared with the control group the diaphragm in patients with cervical spinal cord injury is hypertrophied and the diaphragm excursion is greater. Ultrasound is a highly reliable tool for the evaluation of diaphragm thickness and excursion in patients with cervical spinal cord injury.Trial Registration: This trail was registered in Chinese Clinical Trial Registry (NO. ChiCTR-ROC-17010973).

Rehabilitation Effects of Acupuncture on the Diaphragm Dysfunction in Chronic Obstructive Pulmonary Disease: A Systematic Review

Introduction

Diaphragm dysfunction is a significant extrapulmonary effect in chronic obstructive pulmonary disease (COPD), which is manifested by changes in diaphragm structure and reduced diaphragm strength. Acupuncture is a traditional rehabilitation technique in China, which has been used in rehabilitation for COPD. But whether acupuncture can improve the diaphragm function of COPD patients remains to be verified.

Objective

The objective of this study was to evaluate the rehabilitation effects of acupuncture on diaphragm dysfunction in patients with COPD.

Methods

The authors retrieved in CNKI, VIP, SinoMed, PubMed, Ebsco, Web of Science, from inception to November 2020, for relevant randomized control trials. Two researchers independently screened the articles and extracted the data. The quality of the included studies was evaluated by Physiotherapy Evidence Database scale. The primary outcome measures were maximal inspiratory pressure and the scale for accessory respiratory muscle mobilization, the secondary outcome measures were pulmonary function-related indicators and arterial blood gas indicators.

Results

Nine articles were finally obtained. Seven studies added acupuncture to standard treatment for patients with diaphragm dysfunction in COPD and found statistically significant changes in the maximum inspiratory pressure and the scale for accessory respiratory muscle mobilization. Two studies have proved that use acupuncture combined with other Traditional Chinese Medicine methods in the rehabilitation for COPD can effectively improve the diaphragm strength and diaphragmatic motor performance. Seven studies showed that acupuncture has obvious improvement in pulmonary ventilation function. Seven studies reported significant differences in arterial blood gas pre- to post-intervention.

Conclusion

This systematic review found that acupuncture can effectively enhance the diaphragm strength, relieve respiratory muscle fatigue, it can also play a promoting role in improving lung function, hypoxia, and carbon dioxide retention, as well as preventing and alleviating respiratory failure. The generalizability of these results is limited by the design of the included studies.

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

BACKGROUND

Arthroscopic shoulder surgery causes severe postoperative pain. An interscalene brachial plexus block provides adequate analgesia, but unintended spread of the local anesthetic administered may result in a phrenic nerve block, usually associated with a nonnegligible incidence of acute hemidiaphragmatic paralysis. The main purpose of this trial will be to analyze the incidence of hemidiaphragmatic paralysis ensuing after interscalene brachial plexus block in patients undergoing arthroscopic shoulder surgery administered a standard volume (20 ml) vs. a low volume (10 ml) of levobupivacaine 0.25%.

METHODS

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

DISCUSSION

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

TRIAL REGISTRATION

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

Investigating the correlation between pulmonary function tests and ultrasonographic diaphragm measurements and the effects of respiratory exercises on these parameters in hemiplegic patients

Objective: To investigate the correlation of DUS and pulmonary function tests (PFTs), and investigate the effects of respiratory exercises on the above parameters.Methods: For the treatment group (n=20), neurological rehabilitation and respiratory exercise program, and for the control group (n=21), only a neurological rehabilitation program was implemented for 30 sessions. Forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), end-inspiration diaphragm thickness (IDT), end-expiratory diaphragm thickness (EDT), and diaphragm thickening ratio (DTR) were measured pre- and post-treatment.Results: IDTs and EDTs as well as DTRs of affected side (p < .001, .001, and .03, respectively) and intact side (p < .001, .001, and .02, respectively) were found to improve post-treatment than before treatment in the treatment group. Similarly, FVC, FEV1, and FEV1/FVC, were better post-treatment than before treatment in the treatment group. Moreover, the affected side IDT was positively correlated with FVC and FEV1 before treatment (r = .38, p = .03 and r = .35, p = .02) and post-treatment (r = .46, p = .02 and r = .39, p = .03). The affected side DTR was positively correlated with FVC and FEV1 before treatment (r = .44, p = .01 and r = .40, p = .02) and post-treatment (r = .32, p = .03 and r = .40, p = .04).Conclusion: DUS can be used for the evaluation of respiratory problems in stroke patients. Moreover, breathing exercises improve these parameters in stroke patients, and they can be followed up by DUS.

Current and future applications of ultrasound imaging in peripheral nerve disorders

Neuromuscular ultrasound (NMUS) is a rapidly evolving technique used in neuromuscular medicine to provide complimentary information to standard electrodiagnostic studies. NMUS provides a dynamic, real time assessment of anatomy which can alter both diagnostic and management pathways in peripheral nerve disorders. This review describes the current and future techniques used in NMUS and details the applications and developments in the diagnosis and monitoring of compressive, hereditary, immune-mediated and axonal peripheral nerve disorders, and motor neuron diseases. Technological advances have allowed the increased utilisation of ultrasound for management of peripheral nerve disorders; however, several practical considerations need to be taken into account to facilitate the widespread uptake of this technique.

Does it make difference to measure diaphragm function with M mode (MM) or B mode (BM)?

Diaphragm dysfunction occurs in mechanically ventilated subjects. Recent literature suggests that diaphragm thickening fraction (DTF) measured by ultrasound can be useful to predict weaning outcome. However, there is no standardized approach in the measurement of diaphragm thickness (DT) and limited data exists comparing different measurement techniques of diaphragm thickness (M mode-MM or B mode-BM). The goal of this study was to compare MM with BM in the measurements of DT and excursion in the ICU subjects. DT measurements were obtained from the right diaphragm during tidal and maximal inspiratory breathing. Three measurements of the DT were taken both in MM and BM and their mean values were calculated. DT was measured during inspiration and expiration and DTF was calculated. Excursion of diaphragm was also measured with MM and BM during tidal and maximal inspiratory breathing. Bias and agreement between the two measurement methods were evaluated with Bland and Altman test. Sixty-two subjects were enrolled in the study. While 25 (40%) subjects were receiving invasive mechanical ventilation, 14 (23%) subjects ventilated noninvasively. There were no significant difference between the measurement results of MM and BM. BM and MM tidal diaphragm measurements during the inspiratory (0.3 ± 0.08 and 0.31 ± 0.08 cm; P = 0.022), expiratory (0.24 ± 0.07 and 0.24 ± 0.07 cm; P = 0.315) phases and tidal DTF were (27 ± 16 and 31 ± 14%, P = 0.089) respectively. Results of our study suggests that except tidal inspiratory diaphragm thickness, all thickness and excursion measurements with MM and BM are very compatible with each other. Further studies are necessarry to confirm our results and to standardize the measurements of diaphragm.

Ultrasonography of Diaphragm Can Predict Pulmonary Function in Spinal Cord Injury Patients: A Pilot Case-Control Study

BACKGROUND Ultrasonography of the diaphragm is an under-utilized instrument in cervical spinal cord injury patients. We conducted a pilot study to first compare the difference of diaphragm thickness and the excursion between patients with cervical spinal cord injury and healthy volunteers, and second to correlate diaphragmic ultrasonography and pulmonary function in cervical spinal cord injury patients. MATERIAL AND METHODS Thirty patients with C4-C5 cervical spinal cord injury of more than 1 year and thirty healthy volunteers were included in this study. All demographic data were evaluated. All participants underwent diaphragmic ultrasonography evaluation and pulmonary function test. Diaphragm thickness of both sides and diaphragm excursions of the right hemi-diaphragm were obtained at the end of quiet tidal breathing and maximal inspiration. We compared diaphragmatic thickness and excursions, and we analyzed the relationship between diaphragmatic ultrasonography and pulmonary function. RESULTS All spinal cord injury patients had restrictive pulmonary dysfunction compared to the control group of healthy volunteers. Diaphragm thickness on both sides was significantly increased in spinal cord injury patients. Diaphragmatic excursion in spinal cord injury patients was increased on the right hemi-diaphragm during tidal breathing. However, the right hemi-diaphragmatic excursion was no difference in both groups during maximal inspiration. Right hemi-diaphragmatic excursion during deep breathing correlated positively with expiratory volume in 1 second (P<0.01) and forced vital capacity (P<0.01). Right hemi-diaphragm thickness at end of maximum inspiration correlated positively with expiratory volume in 1 second (P<0.01) and forced vital capacity (P<0.01). Left hemi-diaphragm thickness at end of maximum inspiration correlated positively with expiratory volume in 1 second (P<0.01) and forced vital capacity (P<0.01). CONCLUSIONS Diaphragm thickness and motion of the cervical spinal cord injury patients were different from controls. Pulmonary function was impaired in spinal cord injury patients. Ultrasonography of the diaphragm as a non-invasive method that is correlated with pulmonary function.

Neuromuscular Ultrasound: Clinical Applications and Diagnostic Values

Advances in high-resolution ultrasound have provided clinicians with unique opportunities to study diseases of the peripheral nervous system. Ultrasound complements the clinical and electrophysiology exam by showing the degree of abnormalities in myopathies, as well as spontaneous muscle activities in motor neuron diseases and other disorders. In experienced hands, ultrasound is more sensitive than MRI in detecting peripheral nerve pathologies. It can also guide needle placement for electromyography exam, therapeutic injections, and muscle biopsy. Ultrasound enhances the ability to detect carpal tunnel syndrome and other focal nerve entrapment, as well as pathological nerve enlargements in genetic and acquired neuropathies. Furthermore, ultrasound can potentially be used as a biomarker for muscular dystrophy and spinal muscular atrophy. The combination of electromyography and ultrasound can increase the diagnostic certainty of amyotrophic lateral sclerosis, aid in the localization of brachial plexus or peripheral nerve trauma and allow for surveillance of nerve tumor progression in neurofibromatosis. Potential limitations of ultrasound include an inability to image deeper structures, with lower sensitivities in detecting neuromuscular diseases in young children and those with mitochondrial myopathies, due to subtle changes or early phase of the disease. As well, its utility in detecting critical illness neuromyopathy remains unclear. This review will focus on the clinical applications of neuromuscular ultrasound. The diagnostic values of ultrasound for screening of myopathies, neuropathies, and motor neuron diseases will be presented.

Neuromuscular ultrasound in clinical practice: A review

Neuromuscular ultrasound (NMUS) is becoming a standard element in the evaluation of peripheral nerve and muscle disease. When obtained simultaneously to electrodiagnostic studies, it provides dynamic, structural information that can refine a diagnosis or identify a structural etiology. NMUS can improve patient care for those with mononeuropathies, polyneuropathy, motor neuron disease and muscle disorders. In this article, we present a practical guide to the basics of NMUS and its clinical application. Basic ultrasound physics, scanning techniques and clinical applications are reviewed, along with current challenges.

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.

Reduced Hemidiaphragmatic Paresis With a "Corner Pocket" Technique for Supraclavicular Brachial Plexus Block: Single-Center, Observer-Blinded, Randomized Controlled Trial

BACKGROUND AND OBJECTIVE

Hemidiaphragmatic paresis is common after supraclavicular brachial plexus block (SCBPB). In this randomized trial, we compared the incidence of hemidiaphragmatic paresis in patients who had local anesthetic injected primarily in the corner pocket (defined as the intersection of the first rib and subclavian artery) during SCBPB with that of patients who underwent injection primarily inside the neural cluster.

METHODS

Thirty-six patients scheduled for right elbow, forearm, wrist, or hand surgery under SCBPB (using 12.5 mL of 0.75% ropivacaine and 12.5 mL of 2% lidocaine with 1:200,000 epinephrine) were randomly assigned to 1 of 2 groups. In group CP, local anesthetic was injected primarily in the corner pocket (20 mL) and secondarily inside the neural cluster (5 mL). In group NC, local anesthetic was deposited primarily inside the neural cluster (20 mL) and secondarily in the corner pocket (5 mL). The primary outcome was the incidence of hemidiaphragmatic paresis, as measured by M-mode ultrasonography 30 minutes after SCBPB.

RESULTS

The incidence of hemidiaphragmatic paresis was significantly lower in group CP than in group NC (27.8% vs 66.7%, P = 0.019). The median decreases in forced expiratory volume at 1 second (7.5% [interquartile range, 3.3%-17.1%] vs 24.4% [interquartile range, 10.2%-31.2%]; P = 0.010) and forced vital capacity (6.4% [interquartile range, 3.3%-11.1%] vs 19.3% [interquartile range, 13.7%-33.2%]; P = 0.001) were also lower in group CP than in group NC.

CONCLUSIONS

The incidence of hemidiaphragmatic paresis was effectively reduced when local anesthetic was injected primarily in the corner pocket during right-sided SCBPB. However, the 28% incidence of hemidiaphragmatic paresis associated with the corner pocket technique may still represent a prohibitive risk for patients with preexisting pulmonary compromise.

CLINICAL TRIAL REGISTRATION

This study was registered at Clinical Trial Registry of Korea, identifier KCT0001769.

Body Position Affects Ultrasonographic Measurement of Diaphragm Contractility

PURPOSE

(1) Determine whether ultrasonography can detect differences in diaphragm contractility between body positions. (2) Perform reliability analysis of diaphragm thickness measurements in each test condition.

METHODS

We used a repeated-measures experimental design with 45 healthy adults where 3 B-mode ultrasound images were collected at peak-inspiration and end-expiration in supine, sitting, and standing. Mean diaphragm thickening fractions were calculated for each test position. Statistical significance was tested using 1-way repeated-measures analysis of variance with planned comparisons. For reliability analysis, the intraclass correlation coefficient (3, 3) was calculated.

RESULTS

Mean diaphragm thickening fraction increased from 60.2% (95% confidence interval [CI] 53.0%, 67.9%) in supine, to 96.5% (95% CI 83.2%, 109.9%) while seated and to 173.8% (95% CI 150.5%, 197.1%) while standing. Body position was a significant factor overall (P < .001), as were comparisons between each individual position (P < .001). Intraobserver reliability was excellent (>0.93) for all body positions tested.

CONCLUSIONS

Ultrasound imaging detected positional differences in diaphragm contractility. The effect of gravitational loading on diaphragm length-tension, and body position-mediated changes in intra-abdominal pressure may explain the differences found. Future research should address methodological concerns and apply this method to patients participating in early mobilization programs in the intensive care unit.

Ultrasound Identification of Diaphragm by Novices Using ABCDE Technique

BACKGROUND AND OBJECTIVES

In this study, we examined the consistency, rapidity, and reproducibility of the ABCDE technique for diaphragm identification. Operators using this method place the probe at the Anterior axillary line, watch for Breathing (lung sliding), and then move the probe Caudally to identify the Diaphragm for Examination.

METHODS

A convenience sample of 100 patients was recruited from the preadmission clinic. Two novice operators each scanned the diaphragm using a linear ultrasound transducer in B-mode. Both operators completed the examination on all participants using the ABCDE technique, their times were averaged, and clinical success was defined as identification of the diaphragm in less than 2 minutes.

RESULTS

An average of 33.7 seconds was taken to scan and identify the right hemidiaphragm (RD) (median, 25 seconds; 95% confidence interval, 28.8-38.5 seconds) with a 98% clinical success ratio, and an average of 46.9 seconds was taken to identify the left hemidiaphragm (LD) (median, 39.5 seconds; 95% confidence interval, 40.2-53.6 seconds) with a 97% clinical success ratio. In patients with a body mass index (BMI) of less than 30 kg/m, a 100% success ratio was seen when scanning the RD and 97% when scanning the LD. For those with a BMI of 30 kg/m or greater, a 94% success rate was seen when scanning the RD and 97% when scanning the LD. No clinically significant differences were found between the times required for scanning either side of the diaphragm, regardless of the BMI.

CONCLUSIONS

The ABCDE technique demonstrates a fast, reliable, and simple method in which ultrasound can be used to visualize the diaphragm.

Primary Acute Neuromuscular Respiratory Failure

Neurologists are often called to evaluate patients with both defined and undiagnosed neuromuscular disorders when respiratory failure develops to determine if there is a neuromuscular cause. Being able to confidently diagnose neuromuscular respiratory failure and intervene appropriately is imperative, as early intervention and determination of the cause have survival implications. Outcomes are poor when the cause of neuromuscular weakness and resultant respiratory failure cannot be identified. This review discusses the clinical recognition of primary neuromuscular respiratory failure, its pathophysiology, diagnostic evaluation, and management, focusing on management of respiratory failure in the setting of Guillain-Barré syndrome and myasthenic crisis.

Intensive Care Unit-Acquired Weakness

Intensive care unit-acquired weakness (ICUAW) is a substantial contributor to long-term disability in survivors of critical illness. Critical illness polyneuropathy, critical illness myopathy, and muscle atrophy from disuse contribute in various proportions to ICUAW. ICUAW is a clinical diagnosis supported by electrophysiology and newer diagnostic tests, such as muscle ultrasound. Risk factor reduction, including the aggressive treatment of sepsis and early mobilization, improves outcome. Although some patients with ICUAW experience a full recovery, for others improvement is slow and incomplete and quality of life is adversely affected. This article examines aspects of ICUAW and identifies potential areas of further study.

Diagnostic Approach and Investigation in Sleep Medicine

PURPOSE OF REVIEW

This article provides a clinical approach to the appropriate investigation and diagnosis of sleep disorders commonly seen by neurologists.

RECENT FINDINGS

Home sleep apnea testing in appropriate situations can replace laboratory polysomnography in many cases of uncomplicated sleep apnea. Multiple sleep latency tests must be performed meticulously and interpreted in the clinical setting to avoid overdiagnoses of narcolepsy. Human leukocyte antigen testing has limited utility in establishing a diagnosis of narcolepsy because a positive test has low specificity. Rapid eye movement (REM) sleep behavior disorder is frequently the first manifestation of an evolving synucleinopathy, and a careful history and neurologic examination are needed to determine other early features of these disorders.

SUMMARY

A meticulous history from the patient, supplemented by collateral history from an observer, is essential to establishing the diagnosis of sleep disorders. Judicious supplementary use of investigations, such as laboratory polysomnography, home sleep apnea testing, wrist actigraphy, and multiple sleep latency tests, can confirm the correct diagnosis. This article describes an approach to the sleepy patient, the patient with neuromuscular disease and possible sleep-disordered breathing, the patient with restless legs syndrome, and young and older patients with abnormal movements during sleep.

Respiratory failure because of neuromuscular disease

PURPOSE OF REVIEW

Understanding the mechanisms and abnormalities of respiratory function in neuromuscular disease is critical to supporting the patient and maintaining ventilation in the face of acute or chronic progressive impairment.

RECENT FINDINGS

Retrospective clinical studies reviewing the care of patients with Guillain-Barré syndrome and myasthenia have shown a disturbingly high mortality following step-down from intensive care. This implies high dependency and rehabilitation management is failing despite evidence that delayed improvement can occur with long-term care. A variety of mechanisms of phrenic nerve impairment have been recognized with newer investigation techniques, including EMG and ultrasound. Specific treatment for progressive neuromuscular and muscle disease has been increasingly possible particularly for the treatment of myasthenia, metabolic myopathies, and Duchenne muscular dystrophy. For those conditions without specific treatment, it has been increasingly possible to support ventilation in the domiciliary setting with newer techniques of noninvasive ventilation and better airway clearance. There remained several areas of vigorous debates, including the role for tracheostomy care and the place of respiratory muscle training and phrenic nerve/diaphragm pacing.

SUMMARY

Recent studies and systematic reviews have defined criteria for anticipating, recognizing, and managing ventilatory failure because of acute neuromuscular disease. The care of patients requiring long-term noninvasive ventilatory support for chronic disorders has also evolved. This has resulted in significantly improved survival for patients requiring domiciliary ventilatory support.

Respiratory manifestations in late-onset Pompe disease: a case series conducted in Brazil

Objective:

To describe respiratory function in a series of patients with late-onset Pompe disease after the definitive diagnosis and before enzyme replacement therapy.

Methods:

This was a cross-sectional study involving patients with a definitive molecular diagnosis of late-onset Pompe disease. The data analyzed included age at symptom onset; age at definitive diagnosis; type of initial symptoms; time from symptom onset to diagnosis; FVC in the sitting and supine positions; six-minute walk distance; and locomotor ability. Analyses were carried out using frequencies, medians, minimum values, and maximum values.

Results:

Six patients were included in the study. The median age at symptom onset was 15 years (range, 13-50 years), and the median age at diagnosis was 39.5 years (range, 10-64 years). The median time from symptom onset to diagnosis was 8 years (range, 0-45 years). In all cases, the initial manifestation of the disease had been motor weakness. The median FVC in percentage of the predicted value (FVC%) in the sitting and supine positions was 71.0% (range, 22.9-104.6%) and 58.0% (range, 10.9-106.9%), respectively. The median ΔFVC% was 24.5% (range, −4.59 to 52.40%).The median six-minute walk distance was 391.7 m (range, 97-702 m) .

Conclusions:

In this case series, the time from symptom onset to diagnosis was long. Although respiratory signs or symptoms were not the initial manifestations of the disease, 66.7% of the patients showed reduced FVC% in the sitting and supine positions at diagnosis.

The neurology of acutely failing respiratory mechanics

Forces involved in breathing-which effectively pull in air-are the diaphragmatic, intercostal, spine, and neck muscles. Equally important is the bulbar musculature maintaining the architecture of a patent airway conduit and abdominal wall and internal intercostal muscles providing cough. Acute injury along a neural trajectory from brainstem to muscle will impair the coordinated interaction between these muscle groups. Acutely failing respiratory mechanics can be caused by central and peripheral lesions. In central lesions, the key lesion is in the nucleus ambiguus innervating the dilator muscles of the soft palate, pharynx, and larynx, but abnormal respiratory mechanics rarely coincide with abnormalities of the respiratory pattern generator. In peripheral lesions, diaphragmatic weakness is a main element, but in many neuromuscular disorders mechanical upper airway obstruction from oropharyngeal weakness contributes equally to an increased respiratory load. The neurology of breathing involves changes in respiratory drive, rhythm, mechanics, and dynamics. This review focuses on the fundamentals of abnormal respiratory mechanics in acute neurologic conditions, bedside judgment, interpretation of additional laboratory tests, and initial stabilization, with practical solutions provided. Many of these respiratory signs are relevant to neurologists, who in acute situations may see these patients first. Ann Neurol 2017;81:485-494.

Utility Of diaphragm ultrasound in myopathy

INTRODUCTION

Ultrasound (US) evaluation of diaphragm thickness and contractility is an effective tool in neurogenic diaphragm dysfunction. There are limited data about the value of this technique in patients with myopathy.

METHODS

We performed a retrospective chart review of cases with electromyography (EMG) -confirmed myopathy and real-time US evaluation of the diaphragm. Diaphragm thickness and thickening ratio (maximal inspiration/expiration) were measured. Demographic, imaging, pathology, and genetic data were reviewed, and the clinical diagnosis was recorded.

RESULTS

There were 19 eligible cases, of which 14 (73.7%) had abnormal US findings. Mean diaphragm thickness was 0.12 cm (SD 0.10), and the mean thickening ratio was 1.29 (SD 0.35). In all cases with abnormal US evaluation, the thickening ratio was abnormal. There were no cases with abnormal thickness alone.

CONCLUSIONS

US examination can detect diaphragm dysfunction in myopathy. It is important to measure both the baseline thickness and thickening ratio to maximize sensitivity. Muscle Nerve 55: 427-429, 2017.

Practical Recommendations for Diagnosis and Management of Respiratory Muscle Weakness in Late-Onset Pompe Disease

Pompe disease is an autosomal-recessive lysosomal storage disorder characterized by progressive myopathy with proximal muscle weakness, respiratory muscle dysfunction, and cardiomyopathy (in infants only). In patients with juvenile or adult disease onset, respiratory muscle weakness may decline more rapidly than overall neurological disability. Sleep-disordered breathing, daytime hypercapnia, and the need for nocturnal ventilation eventually evolve in most patients. Additionally, respiratory muscle weakness leads to decreased cough and impaired airway clearance, increasing the risk of acute respiratory illness. Progressive respiratory muscle weakness is a major cause of morbidity and mortality in late-onset Pompe disease even if enzyme replacement therapy has been established. Practical knowledge of how to detect, monitor and manage respiratory muscle involvement is crucial for optimal patient care. A multidisciplinary approach combining the expertise of neurologists, pulmonologists, and intensive care specialists is needed. Based on the authors' own experience in over 200 patients, this article conveys expert recommendations for the diagnosis and management of respiratory muscle weakness and its sequelae in late-onset Pompe disease.