Diaphragmatic paralysis: the use of M mode ultrasound for diagnosis in adults

Evaluation and management of dyspnea as the dominant presenting feature in neuromuscular disorders

Dyspnea is a common symptom in neuromuscular disorders and, although multifactorial, it is usually due to respiratory muscle involvement, associated musculoskeletal changes such as scoliosis or, in certain neuromuscular conditions, cardiomyopathy. Clinical history can elicit symptoms such as orthopnea, trepopnea, sleep disruption, dysphagia, weak cough, and difficulty with secretion clearance. The examination is essential to assist with the diagnosis of an underlying neurologic disorder and determine whether dyspnea is from a cardiac or pulmonary origin. Specific attention should be given to possible muscle loss, use of accessory muscles of breathing, difficulty with neck flexion/extension, presence of thoraco-abdominal paradox, conversational dyspnea, cardiac examination, and should include a detailed neurological examination directed at the suspected differential diagnosis. Pulmonary function testing including sitting and supine spirometry, measures of inspiratory and expiratory muscle strength, cough peak flow, sniff nasal inspiratory pressure, pulse oximetry, transcutaneous CO2, and arterial blood gases will help determine the extent of the respiratory muscle involvement, assess for hypercapnic or hypoxemic respiratory failure, and qualify the patient for noninvasive ventilation when appropriate. Additional testing includes dynamic imaging with sniff fluoroscopy or diaphragm ultrasound, and diaphragm electromyography. Polysomnography is indicated for sleep related symptoms that are not otherwise explained. Noninvasive ventilation alleviates dyspnea and nocturnal symptoms, improves quality of life, and prolongs survival. Therapy targeted at neuromuscular disorders may help control the disease or favorably modify its course. For patients who have difficulty with secretion clearance, support of expiratory function with mechanical insufflation-exsufflation, oscillatory devices can reduce the aspiration risk.

Comparison between low-volume local anesthetic with intravenous dexamethasone and conventional volume without dexamethasone for superior trunk block after arthroscopic shoulder surgery: a randomized controlled non-inferiority trial

INTRODUCTION

This study aimed to investigate whether low-volume local anesthetic with intravenous dexamethasone can reduce the incidence of diaphragmatic paresis while maintaining the analgesic duration compared with conventional volume of local anesthetic without intravenous dexamethasone when performing ultrasound-guided superior trunk block in patients undergoing arthroscopic shoulder surgery.

METHODS

Eighty-four adult patients undergoing arthroscopic shoulder surgery under general anesthesia were randomly assigned to receive ultrasound-guided superior trunk block using 7 mL of 0.5% ropivacaine with 0.15 mg/kg of intravenous dexamethasone (treatment group), or 15 mL of 0.5% ropivacaine with intravenous normal saline (control group). The co-primary outcomes were (1) the duration of analgesia (time between block completion and onset of surgical pain with a Numeric Rating Scale pain score of 4 or higher), which was compared against a non-inferiority margin of 3 hours, and (2) the incidence of diaphragmatic paresis evaluated using M-mode ultrasonography in the post-anesthesia care unit.

RESULTS

The mean duration of analgesia was 12.4 (6.8) and 11.2 (4.6) hours in the treatment and control groups, respectively (mean difference: -1.2 hours; 95% CI -3.8 to 1.3]; p for non-inferiority<0.001), meeting the non-inferiority criteria. The incidence of diaphragmatic paresis was 45.2% and 85.4% in the treatment and control groups, respectively (relative risk: 0.53; 97.5% CI 0.35 to 0.80; p<0.001).

CONCLUSIONS

Superior trunk block using low-volume local anesthetic with intravenous dexamethasone can reduce the incidence of diaphragmatic paresis while providing non-inferior analgesic duration compared with the conventional volume of local anesthetic in patients undergoing arthroscopic shoulder surgery.

TRIAL REGISTRATION NUMBER

Clinical Research Information Service of Republic of Korea Registry (KCT0005998).

Diagnosis of hemidiaphragm paralysis: refine ultrasound criteria

Background

Ultrasound has demonstrated its interest in the analysis of diaphragm function in patients with respiratory failure. The criteria used to diagnose hemidiaphragm paralysis are not well defined.

Methods

The aim of this observational retrospective study was to describe the ultrasound findings in 103 patients with diaphragm paralysis, previously diagnosed by conventional methods after various circumstances such as trauma or surgery. The ultrasound study included the recording of excursions of both diaphragmatic domes and the measurement of inspiratory thickening.

Results

On paralyzed hemidiaphragm, thickening was less than 20% in all patients during deep inspiration. Thinning was recorded in 53% of cases. In some cases, the recording of the thickening could be difficult. The study of motion during voluntary sniffing reported a paradoxical excursion in all but one patient. During quiet breathing, an absence of movement or a paradoxical displacement was observed. During deep inspiration, a paradoxical motion at the beginning of inspiration followed by a reestablishment of movement in the cranio-caudal direction was seen in 82% of cases. In some patients, there was a lack of movement followed, after an average delay of 0.4 s, by a cranio-caudal excursion. Finally, in 4 patients no displacement was recorded. Evidence of hyperactivity (increased inspiratory thickening and excursion) of contralateral non-paralyzed hemidiaphragm was observed.

Conclusion

To accurately detect hemidiaphragm paralysis, it would be interesting to combine the ultrasound study of diaphragm excursion and thickening. The different profiles reported by our study must be known to avoid misinterpretation.

Point-of-Care Ultrasound to Assess Diaphragmatic Paralysis in Resource-Limited Setting: A Case Series

Diaphragmatic dysfunction can arise from various factors, and Guillain-Barre syndrome, characterized by acute inflammatory polyradiculoneuropathy, is one such cause that may result in respiratory failure due to diaphragmatic paralysis. Prompt recognition and timely intervention, including airway protection and addressing the underlying pathology, are crucial for achieving optimal patient outcomes. Point-of-care ultrasound, specifically utilizing the M-mode function, can be employed for individuals displaying symptoms of diaphragmatic paralysis. This diagnostic approach is uncomplicated an effective tool for serial follow-up. In this context, we present a case series involving three patients with diaphragmatic paralysis in a limited-resource setting.

Imaging of the Diaphragm: A Primer

The diaphragm is a critical musculotendinous structure that contributes to respiratory function. Disorders of the diaphragm are rare and diagnostically challenging. Herein, the author reviews the radiologic options for the assessment of the diaphragm.

Bi-parametric MRI of the Diaphragm Using Dynamic and Static Images: The Initial Experience

BACKGROUND

With recent technological advances, magnetic resonance imaging (MRI) has offered new sequences that can evaluate the real-time motion of anatomic structures. This study aims to evaluate the interobserver agreement in the diagnosis of diaphragmatic dysfunctions using bi-parametric MRI, in which dynamic sequences for diaphragm movement and static sequences for soft tissue resolution are used together to provide a visualization of the diaphragm.

METHODOLOGY

Twenty-nine cases that underwent a bi-parametric magnetic resonance examination which includes coronal T2 single-shot turbo spin echo and the coronal SENSE single-shot balanced turbo field echo real-time sequences were retrospectively evaluated. The images of the patients were assessed by two independent observers. Cohen's kappa coefficient was calculated to evaluate the interobserver agreement.

RESULTS

The mean age of the patients was 44.86 ± 17.57, ranging from 18 to 80 years. The kappa value was calculated as 0.889, indicating a strong agreement between the interobservers.

CONCLUSIONS

Our experience suggests that bi-parametric MRI is a promising tool in the evaluation of diaphragmatic abnormalities.

Ultrasound-based measurement of central adiposity: Key considerations and guidelines

Central adiposity, which is visceral and subcutaneous adiposity in the abdominal region, is a known risk factor for developing chronic cardiometabolic diseases. Central adiposity can be measured relatively inexpensively using ultrasound. Ultrasound has been shown to be precise and reliable, with measurement accuracy comparable to computed tomography and magnetic resonance. Despite the advantages conferred by ultrasound, widespread adoption has been hindered by lack of reliable standard operating procedures. To consolidate the literature and bring clarity to the use of ultrasound-derived measures of central adiposity, this review outlines (i) the [patho]physiological importance of central adiposity to cardiometabolic disease risk; (ii) an overview of the history and main technical aspects of ultrasound methodology; (iii) key measurement considerations, including transducer selection, subject preparation, image acquisition, image analysis, and operator training; and (iv) guidelines for standardized ultrasound protocols for measuring central adiposity.

Interest of thoracic ultrasound after cardiac surgery or interventional cardiology

Thoracic ultrasound has attracted much interest in detecting pleural effusion or pulmonary consolidation after cardiac surgery. In 2016, Trovato reported, in the World Journal of Cardiology, the interest of using, in addition to echocardiography, thoracic ultrasound. In this editorial, we highlight the value of assessing diaphragm function after cardiac surgery and interventional cardiology procedures. Various factors are able to impair diaphragm function after such interventions. Diaphragm motion may be decreased by chest pain secondary to sternotomy, pleural effusion or impaired muscle function. Hemidiaphragmatic paralysis may be secondary to phrenic nerve damage complicating cardiac surgery or atrial fibrillation ablation. Diagnosis may be delayed. Indeed, respiratory troubles induced by diaphragm dysfunction are frequently attributed to pre-existing heart disease or pulmonary complications secondary to surgery. In addition, elevated hemidiaphragm secondary to diaphragm dysfunction is sometimes not observed on chest X-ray performed in supine position in the intensive care unit. Analysis of diaphragm function by ultrasound during the recovery period appears essential. Both hemidiaphragms can be studied by two complementary ultrasound methods. The mobility of each hemidiaphragms is measured by M-mode ultrasonography. In addition, recording the percentage of inspiratory thickening provides important information about the quality of muscle function. These two approaches make it possible to detect hemidiaphragm paralysis or dysfunction. Such a diagnosis is important because persistent diaphragm dysfunction after cardiac surgery has been shown to be associated with adverse respiratory outcome. Early respiratory physiotherapy is able to improve respiratory function through strengthening of the inspiratory muscles i.e. diaphragm and accessory inspiratory muscles.

Evaluation of computed tomography in the diagnosis of ultrasound-proven diaphragm dysfunction

INTRODUCTION

Computed tomography (CT) is routinely employed on the evaluation of dyspnea, yet limited data exist on its assessment of diaphragmatic muscle. This study aimed to determine the capability of CT in identifying structural changes in the diaphragm among patients with ultrasound-confirmed diaphragmatic dysfunction.

METHODS

Diaphragmatic ultrasounds conducted between 2018 and 2021 at our center in Marseille, France, were retrospectively collected. Diaphragmatic pillars were measured on CT scans at the L1 level and the celiac artery. Additionally, the difference in height between the two diaphragmatic domes in both diaphragmatic dysfunction cases and controls was measured and compared.

RESULTS

A total of 65 patients were included, comprising 24 with diaphragmatic paralysis, 13 with diaphragmatic weakness, and 28 controls. In the case group (paralysis and weakness) with left dysfunctions (n = 24), the CT thickness of the pillars at the level of L1 and the celiac artery was significantly thinner compared with controls (2.0 mm vs. 7.4 mm and 1.8 mm vs. 3.1 mm, p < 0.001 respectively). Significantly different values were observed for paralysis (but not weakness) in the right dysfunction subgroup (n = 15) (2.6 mm vs. 7.4 mm and 2.2 mm vs. 3.8 mm, p < 0.001 respectively, for paralysis vs. controls). Regardless of the side of dysfunction, a significant difference in diaphragmatic height was observed between cases and controls (7.70 cm vs. 1.16 cm and 5.51 cm vs. 1.16 cm, p < 0.001 for right and left dysfunctions, respectively). Threshold values determined through ROC curve analyses for height differences between the two diaphragmatic domes, indicative of paralysis or weakness in the right dysfunctions, were 4.44 cm and 3.51 cm, respectively. Similarly for left dysfunctions, the thresholds were 2.70 cm and 2.48 cm, respectively, demonstrating good performance (aera under the curve of 1.00, 1.00, 0.98, and 0.79, respectively).

CONCLUSION

In cases of left diaphragmatic dysfunction, as well as in paralysis associated with right diaphragmatic dysfunction, CT revealed thinner pillars. Additionally, a notable increase in the difference in diaphragmatic height demonstrated a strong potential to identify diaphragmatic dysfunction, with specific threshold values.

The diagnostic utility of inspiratory-expiratory radiography for the assessment of phrenic nerve palsy associated with brachial plexus injury

BACKGROUND

The phrenic nerve is commonly injured with trauma to the brachial plexus. Hemi-diaphragmatic paralysis may be well-compensated in healthy individuals at rest but can be associated with persistent exercise intolerance in some patients. This study aims to determine the diagnostic value of inspiratory-expiratory chest radiography compared to intraoperative stimulation of the phrenic nerve for assessing phrenic nerve injury associated with brachial plexus injury.

METHODS

Over a 21-year period, the diagnostic utility of three-view inspiratory-expiratory chest radiography for identification of phrenic nerve injury was determined by comparison to intraoperative phrenic nerve stimulation. Multivariate regression analysis was used to identify independent predictors of phrenic nerve injury and having an incorrect radiographic diagnosis.

RESULTS

A total of 237 patients with inspiratory-expiratory chest radiography underwent intraoperative testing of phrenic nerve function. Phrenic nerve injury was present in approximately one-fourth of cases. Preoperative chest radiography had a sensitivity of 56%, specificity of 93%, positive predictive negative of 75%, and negative predictive value of 86% for identification of a phrenic nerve palsy. Only C5 avulsion was found to be a predictor of having an incorrect diagnosis of phrenic nerve injury on radiography.

CONCLUSION

While inspiratory-expiratory chest radiography has good specificity for detecting phrenic nerve injuries, a high number of false negatives suggest that it should not be relied upon for routine screening of dysfunction after traumatic brachial plexus injury. This is likely multifactorial and relates to variation in diaphragm shape and position, as well as limitations regarding static image interpretation of a dynamic process.

An optimized optical-flow-based method for quantitative tracking of ultrasound-guided right diaphragm deformation

OBJECTIVES

To develop a quantitative analysis method for right diaphragm deformation. This method is based on optical flow and applied to diaphragm ultrasound imaging.

METHODS

This study enrolls six healthy subjects and eight patients under mechanical ventilation. Dynamic images with 3-5 breathing cycles were acquired from three directions of right diaphragm by a portable ultrasound system. Filtering and density clustering algorithms are used for denoising Digital Imaging and Communications in Medicine (DICOM) data. An optical flow based method is applied to track movements of the right diaphragm. An improved drift correction algorithm is used to optimize the results. The method can automatically analyze the respiratory cycle, inter-frame/cumulative vertical and horizontal displacements, and strain of the input right diaphragm ultrasound image.

RESULTS

The optical-flow-based diaphragm ultrasound image motion tracking algorithm can accurately track the right diaphragm during respiratory motion. There are significant differences in horizontal and vertical displacements in each section (p-values < 0.05 for all). Significant differences are found between healthy subjects and mechanical ventilation patients for both horizontal and vertical displacements in Section III (p-values < 0.05 for both). There is no significant difference in global strain in each section between healthy subjects and mechanical ventilation patients (p-values > 0.05 for all).

CONCLUSIONS

The developed method can quantitatively evaluate the inter-frame/cumulative displacement of the diaphragm in both horizontal and vertical directions, as well as the global strain in three different imaging planes. The above indicators can be used to evaluate diaphragmatic dynamics.

Single port thoracoscopic diaphragm plication: A novel treatment approach to bilateral phrenic nerve palsy and diaphragm paralysis

INTRODUCTION AND IMPORTANCE

The diaphragm is the primary muscle of respiration. Bilateral paralysis of the diaphragm due to phrenic nerve palsy causes severe dyspnoea and is life threatening. Diaphragmatic Plication has shown great promise in treating diaphragm paralysis and has evolved as operative treatment from an open thoracotomy to multiport and robotic video assisted thoracoscopic surgery.

CASE PRESENTATION

Here we present a case of idiopathic bilateral diaphragm paralysis resulting significant deterioration in lung function tests, supplemental oxygen, and ventilator dependence. The patient was treated with a 2-stage operative plication of each hemidiaphragm through a 2.5 cm single incision thoracoscopic technique, which resulted in normalization of lung function tests, elimination of oxygen dependence and negligible analgesia requirements.

CASE DISCUSSION

This is the first case reported in the literature of a single port VATS plication of the diaphragm for the treatment of bilateral phrenic nerve palsy. Surgery, specifically diaphragm plication, is indicated for patients with significant symptoms and persistent paralysis. Video-assisted thoracoscopic surgery (VATS) has evolved from open operations to smaller incisions, offering improved lung function, postoperative pain, hospital stay, morbidity, and mortality.

CONCLUSION

Single port diaphragmatic plication is a novel approach to the treatment of bilateral phrenic nerve palsy. We make the case for indication of the technique for treatment of diaphragmatic paralysis.

Ultrasound assessment of the respiratory system using diaphragm motion-volume indices

Background

Although previous studies have determined limit values of normality for diaphragm excursion and thickening, it would be beneficial to determine the normal diaphragm motion-to-inspired volume ratio that integrates the activity of the diaphragm and the quality of the respiratory system.

Methods

To determine the normal values of selected ultrasound diaphragm motion-volume indices, subjects with normal pulmonary function testing were recruited. Ultrasound examination recorded diaphragm excursion on both sides during quiet breathing and deep inspiration. Diaphragm thickness was also measured. The inspired volumes of the corresponding cycles were systematically recorded using a spirometer. The indices were calculated using the ratio excursion, or percentage of thickening, divided by the corresponding breathing volume. From this corhort, normal values and limit values for normality were determined. These measurements were compared to those performed on the healthy side in patients with hemidiaphragm paralysis because an increase in hemidiaphragm activity has been previously demonstated in such circumstances.

Results

A total of 122 subjects (51 women, 71 men) with normal pulmonary function were included in the study. Statistical analysis revealed that the ratio of excursion, or percentage of thickening, to inspired volume ratio significantly differed between males and females. When the above-mentioned indices using excursion were normalized by body weight, no gender differences were found. The indices differed between normal respiratory function subjects and patients with hemidiaphragm paralysis (27 women, 41 men). On the paralyzed side, the average ratio of the excursion divided by the inspired volume was zero. On the healthy side, the indices using the excursion and the percentage of thickening during quiet breathing or deep inspiration were significantly increased comparedto patients with normal lung function. According to the logistic regression analysis, the most relevant indice appeared to be the ratio of the excursion measured during quiet breathing to the inspired volume.

Conclusion

The normal values of the diaphragm motion-volume indices could be useful to estimate the performance of the respiratory system. Proposed indices appear suitable in a context of hyperactivity.

Training Ultrasound Image Classification Deep-Learning Algorithms for Pneumothorax Detection Using a Synthetic Tissue Phantom Apparatus

Ultrasound (US) imaging is a critical tool in emergency and military medicine because of its portability and immediate nature. However, proper image interpretation requires skill, limiting its utility in remote applications for conditions such as pneumothorax (PTX) which requires rapid intervention. Artificial intelligence has the potential to automate ultrasound image analysis for various pathophysiological conditions. Training models require large data sets and a means of troubleshooting in real-time for ultrasound integration deployment, and they also require large animal models or clinical testing. Here, we detail the development of a dynamic synthetic tissue phantom model for PTX and its use in training image classification algorithms. The model comprises a synthetic gelatin phantom cast in a custom 3D-printed rib mold and a lung mimicking phantom. When compared to PTX images acquired in swine, images from the phantom were similar in both PTX negative and positive mimicking scenarios. We then used a deep learning image classification algorithm, which we previously developed for shrapnel detection, to accurately predict the presence of PTX in swine images by only training on phantom image sets, highlighting the utility for a tissue phantom for AI applications.

Weakness in the intensive care unit

When asked to assess patients in an intensive care unit (ICU) who have respiratory muscle weakness, oropharyngeal weakness and a vulnerable airway, our immediate thought may be of Guillain-Barré syndrome or myasthenia gravis, but there are many other possible causes. For example, previously unrecognised chronic neurological conditions may decompensate and require ICU admission. Clinicians can use various clinical clues to help recognise them and need to understand how patterns of weakness reflect differing causes of reduced consciousness on ICU. Additionally, patients admitted to ICU for any reason may develop weakness during their stay, the most likely cause being ICU-acquired weakness. Assessing patients in ICU is challenging, hampered by physical barriers (machines, tubes), medication barriers (sedatives) and cognitive barriers (delirium, difficulty communicating). Nonetheless, we need to reach a clinical diagnosis, organise appropriate tests and communicate clearly with both patients and ICU colleagues.

Type 2 respiratory failure secondary to left hemidiaphragmatic paralysis

A 73-year-old man presented to the emergency department with worsening orthopnoea and exertional dyspnoea. He denied any other cardiorespiratory symptoms. The patient had a body mass index (BMI) of 23.3 kg·m⁻² (height 163 cm, weight 62 kg). Lung function tests 3 months before admission showed a ratio of forced expiratory volume in 1 s (FEV₁) to forced vital capacity (FVC) of 88%. He had a past medical history of hypothyroidism, for which he was on levothyroxine 50 μg daily, and type 2 diabetes mellitus, for which he was on metformin 500 mg twice daily. Past surgical history included a gastrectomy 3 years prior to admission performed for gastric cancer, which was subsequently complicated by a subphrenic abscess, pancreatitis and residual pancreatic insufficiency. The patient was a lifelong non-smoker, worked in construction, reared birds as a hobby, and lived in an urban area. He was not on any other medication.

This case describes an uncommon presentation of type 2 respiratory failure secondary to left hemidiaphragmatic paralysis. Emphasis is on the multitude of possible causes of hemidiaphragmatic paralysis and how to manage such a presentation.https://bit.ly/3Mcd2XI

Quantitative analysis of diaphragm motion during fluoroscopic sniff test to assist in diagnosis of hemidiaphragm paralysis

The current imaging gold standard for detecting paradoxical diaphragm motion and diagnosing hemidiaphragm paralysis is to perform the fluoroscopic sniff test. The images are visually examined by an experienced radiologist, and if one hemidiaphragm ascends while the other descends, then it is described as paradoxical motion, which is highly suggestive of hemidiaphragm paralysis. However, diagnosis can be challenging because diaphragm motion during sniffing is fast, paradoxical motion can be subtle, and the analysis is based on a 2-dimensional projection of a 3-dimensional surface. This paper presents a case of chronic left hemidiaphragm elevation that was initially reported as mild paradoxical motion on fluoroscopy. After measuring the elevations of the diaphragms and modeling their temporal correlation using Gaussian process regression, the systematic trend of the hemidiaphragmatic motion along with its stochastic properties was determined. When analyzing the trajectories of the hemidiaphragms, no statistically significant paradoxical motion was detected. This could potentially change the prognosis if the patient was to consider diaphragm plication as treatment. The presented method provides a more objective analysis of hemidiaphragm motions and can potentially improve diagnostic accuracy.

Efficacy of superficial cervical plexus block versus cervical retrolaminar block both combined with auriculotemporal nerve block in parotid surgeries

Background

Regional techniques in parotid surgeries include superficial cervical plexus block (SCPB) and auriculotemporal nerve (ATN) block, which can be used as an anesthetic technique for awake parotidectomy. This study aimed to evaluate the efficacy of cervical retrolaminar block (RLB) as an alternative to SCPB both, used in combination with auriculotemporal nerve (ATN) block, in parotid surgery.

Material and methods

A total of 40 patients undergoing parotid surgery were prospectively randomized into either the SCPB group (n = 20) or the cervical RLB group (n = 20) using 20 ml of 0.25% bupivacaine plus 5 mcg\mL epinephrine. Both were combined with ATN block using 5 ml of 0.25% bupivacaine plus 5 mcg\mL epinephrine.

Results

The time to first request for analgesia was longer in the RLB group than the SCPB group. Total intra operative fentanyl consumption and post-operative pethidine consumption in the first 24h were lower in group RLB. All patients (n = 20) in the SCPB group required rescue analgesia using pethidine, while only 40% of patients required pethidine in the RLB group. Visual analog scale was lower in the RLB group from 2 to 24-h post-operatively, but it was associated with hypotension and longer block technique time occurred with RLB than SCPB. There was no significant difference in side effects except for 20% Horner's syndrome in the SCPB group.

Conclusion

Cervical RLB is more effective analgesic technique than SCPB, as the cervical RLB showed longer time to first analgesic request, lower intraoperative anesthetic consumption, lower total post-operative pethidine consumption and lower VAS.

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A study on 40 patient undergoing elective parotid surgery of 2 groups; Cervical retrolaminar block or SCPB.

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Cervical retrolaminar block more effective than SCBP.

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Cervical retrolaminar block is alternative Technique to paravertebral block.

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No significant difference between the two study groups according to complications.

Diaphragmatic excursion by ultrasound: reference values for the normal population; a cross-sectional study in Egypt

Background

Measurement of diaphragmatic motion by ultrasound is being utilized in different aspects of clinical practice. Defining reference values of the diaphragmatic excursion is important to identify those with diaphragmatic motion abnormalities. This study aimed to define the normal range of diaphragmatic motion (reference values) by Mmode ultrasound for the normal population.

Methods

Healthy volunteers were included in this study. Those with comorbidities, skeletal deformity, acute or chronic respiratory illness were excluded. Diaphragmatic ultrasound in the supine position was performed using a lowfrequency probe. The B-mode was applied for diaphragmatic identification, and the M-mode was employed for the recording of the amplitude of diaphragm contraction during quiet breathing, deep breathing and sniffing.

Results

The study included 757 healthy subjects [478 men (63.14%) and 279 women (36.86%)] with normal spirometry and negative history of previous or current respiratory illness. Their mean age and BMI were 45.17 ±14.84 years and 29.36±19.68 (kg/m²). The mean right hemidiaphragmatic excursion was 2.32±0.54, 5.54±1.26 and 2.90±0.63 for quiet breathing, deep breathing and sniffing, respectively, while the left hemidiaphragmatic excursion was 2.35±0.54, 5.30±1.21 and 2.97±0.56 cm for quiet breathing, deep breathing and sniffing, respectively. There was a statistically significant difference between right and left diaphragmatic excursion among all studied subjects. The ratio of right to left diaphragmatic excursion during quiet breathing was (1.009±0.19); maximum 181% and minimum 28%. Only 19 cases showed a right to left ratio of less than 50% (5 men and 14 women). The diaphragmatic excursion was higher in males than females. There was a significant difference in diaphragmatic excursion among age groups. Age, sex and BMI significantly affected the diaphragmatic motion.

Conclusions

Diaphragmatic excursion values presented in this study can be used as reference values to detect diaphragmatic dysfunction in clinical practice. Diaphragmatic motion is affected by several factors including age, sex and body mass index.

The Feasibility of Ultrasonographic Diaphragmatic Excursion in Healthy Dogs: Effect of Positioning, Diaphragmatic Location, and Body Weight of Dogs

Diaphragmatic excursion (DE) has been utilized for detecting respiratory related problems in humans. However, several factors should be considered such as the ultrasound technique and factors intrinsic to patients. Nevertheless, knowledge of the effect of these factors on DE in dogs is still lacking. The aim of this study was to evaluate the proper ultrasound technique by varying postures and diaphragmatic locations for DE measurement and to explore intrinsic factors such as diaphragmatic sides, sex, and body weight of dogs on DE. The prospective, analytic, cross-sectional study included 44 healthy dogs; 12 beagles and 32 dogs of other breeds. The experiment was divided into (i) an exploration of the proper ultrasound technique by varying postures (supine, standing, and recumbent in each of the right and left lateral positions), diaphragmatic locations (middle crus and proximal to the last rib), and diaphragmatic sublocations (xiphoid, mid, and proximal rib) for detection of DE and (ii) the evaluation of canine intrinsic factors affecting DE. The results show that the mid-diaphragmatic sublocation in the middle crus area in almost all positions revealed the highest percentage DE detection. However, DEs were revealed to be more accessible in the supine position. There was no significant difference in DE between the right and the left diaphragms or between the sexes of beagle dogs. However, body weight was significantly correlated with the DE among dogs of various sizes. In conclusion, the posture of the dogs and the diaphragmatic location can affect DE evaluation. Neither sex nor diaphragmatic side had an influence, but body weight was revealed as a major factor in DE in dogs.

Evaluation of diaphragm thickening by diaphragm ultrasonography: a reproducibility and a repeatability study

PURPOSE

We have focused on the two-dimensional (B-mode) and the time-motion (M-mode) analysis of the zone of apposition to determine the reliability of diaphragm ultrasonography in the clinical environment.

METHODS

Ten healthy volunteers were enrolled and studied by three operators with different skills in ultrasonography. For every volunteer, each operator acquired three images of the diaphragm for each side, both in B-mode and in M-mode. Then a fourth operator calculated the thickening fraction (TF), by means of the formula TF = (TEI - TEE)/TEE (TEI is the thickness at end inspiration and TEE the thickness at end expiration). Afterwards, intraclass correlation coefficients (ICCs) were computed on TF to establish reproducibility and repeatability both in the B- and M-modes. A Coefficient of Repeatability or repeatability (CR) ≤ 0.3 was considered acceptable.

RESULTS

Both B-mode (CRs 0.16-0.26) and M-mode (CRs 0.10-0.15) were sufficiently repeatable to assess TF, except for the less experienced operator (CRs B-Mode 0.20-0.32). Reproducibility was moderate to good between operators with CRs much narrower for the M-Mode (0.13-0.14).

CONCLUSIONS

The results of our study have shown that diaphragm ultrasound is repeatable and reproducible when carried out by a radiologist or an intensivist with a basic curriculum in ultrasonography. The method is more accurate when using the M-mode for less experienced operators, and in this case, repeatability and reproducibility are not sufficient to make clinical decisions. No TF value lower than 36% was obtained using both techniques. This suggests the existence of a cut-off value that could be used as an initial tool to discriminate healthy subjects from those affected by diaphragmatic dysfunction.

CLINICAL TRIAL REGISTRATION

EUDRACT 2015-004635-12.

A 65-Year-Old Woman With Dyspnea After Atrial Fibrillation Ablation

CASE PRESENTATION

A 65-year-old woman with a history of chronic persistent atrial fibrillation, tobacco use, and COPD was admitted to the hospital 2 months after catheter ablation for persistent atrial fibrillation and dyspnea. Her dyspnea was present at rest and worsened by exertion with limitation to ambulating less than two blocks. She also endorsed a 1-month history of cough with minimally productive whitish sputum with frequent nocturnal exacerbations and orthopnea. She denied any fevers, chest pain, or hemoptysis.

Shrinking lung syndrome in pediatric systemic lupus erythematosus

OBJECTIVE

To describe clinical, radiological and treatment characteristics in pediatric patients with SLS.

MATERIAL AND METHODS

This is a descriptive and retrospective study in patients under 16 years old with the diagnosis of SLE complicated by SLS at the General Hospital. National Medical Center La Raza. Clinical, radiological and treatment variables were analyzed. Results are shown in frequencies and percentages.

RESULTS

Data from 11 patients, 9 females and 2 males were collected. Mean age at diagnosis of SLS was 12.2 years. Age at diagnosis of SLE was 11.1 years. SLEDAI 17.3. Renal desease 72%, hematological 91%, lymphopenia 63%, mucocutaneous 72%, neurological 9%, arthritis 54%, serositis 91%, fever 81%, secondary antiphospholipid syndrome, low C3 72%, low C4 81%, positive ANA 91%, positive anti-DNA 91%. Regarding clinical manifestations of SLE: cough 81%, dyspnea 91%, hipoxemia 81%, pleuritic pain 71%, average oxygen saturation 83%. Chest X-rays findings: right hemidiaphragm affection 18%, left 63%, bilateral 18%. Elevated hemidiaphragm 91%, atelectasis 18%, pleural effusion 91%, over one third of the cardiac silhouette under the diphragm 36%, bulging diaphragm 45%, 5th. anterior rib that crosses over the diaphragm 91%. M-mode ultrasound: diaphragmatic hypomotility 100%, pleural effusion 63%. Pulmonary function tests: restrictive pattern in 45% of the cases. Treatment was with supplementary oxygen 100%, intubation 18%, antibiotics 100%, steroids 100%, intravenous immunoglobulin 54%, plasmapheresis 18%, cyclophosphamide 54% and rituximab 18%. The clinical course was favorable in 81%.

CONCLUSIONS

SLS should be suspected in patients with SLE and active disease who present hipoxemia, pleuritic pain, cough, dyspnea, pleural effusion and signs of restriction on chest X-rays. Therefore, a diaphragmatic M-mode ultrasound should be performed in order to establish the diagnosis.

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

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

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

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

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

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

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

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

Diaphragmatic excursion: Quantitative measure to assess adequacy of expiratory phase CT chest images

OBJECTIVE

To evaluate diaphragmatic excursion as a quantitative metric for change in lung volume between inspiratory and expiratory chest computed tomography (CT) images.

METHODS

A 12-month retrospective review identified 226 chest CT exams with inspiratory and expiratory phase imaging, 63 in individuals referred with diagnosis of asthma by ICD9/10 code. Exams acquired in the supine position at 1.25 mm slice thickness in each phase were included (n = 30, mean age = 62, M = 15, F = 15). Diaphragmatic excursion was calculated as the difference between axial slices through the lungs on inspiration and expiration, using the lung apex as the cranial bound, and the hemidiaphragm caudally. Inspiratory and expiratory lung and tracheal volumes were calculated through volumetric segmentation. Tracheal morphology was assessed at 1 cm above the level of the aortic arch, and 1 cm above the carina.

RESULTS

Inspiratory and expiratory lung volumes were higher in men (mean I = 5 + 1.6 L, E = 3.1 + 1.2 L) than women (mean I = 3.6 + 0.8 L, E = 2.4 + 0.7 L), p = .005 and p = .047, respectively. Average inspiratory and expiratory tracheal volumes were higher in men (I = 61 + 17 mL, E = 43 + 14) than women (I = 44 + 14, E = 30 + 8), p = .006 and p = .005. Average change in lung and tracheal volume between inspiratory and expiratory scans did not significantly differ between men and women. Average diaphragmatic excursion was 2.5 cm between inspiratory and expiratory scans (2.7 cm in men, 2.3 cm in women; p = .5). There was a strong positive correlation between diaphragmatic excursion and change in lung (r = .84) and tracheal volume (r = .79). A moderate correlation was also found between change in tracheal volume and change in lung volume (r = 0.67). Change in tracheal morphology between inspiratory and expiratory imaging was associated with change in tracheal volume at both 1 cm above the aortic arch (p = .04) and 1 cm above the carina (p = .008); there was no association with diaphragmatic excursion or lung volume.

CONCLUSIONS

Diaphragmatic excursion is a quantitative measure of expiratory effort as validated by both lung and tracheal volumes in asthma patients, and may be more accurate than qualitative assessment based on tracheal morphology.

Diaphragmatic ultrasound: a review of its methodological aspects and clinical uses

The diaphragm is the main muscle of respiration, acting continuously and uninterruptedly to sustain the task of breathing. Diaphragmatic dysfunction can occur secondary to numerous pathological conditions and is usually underdiagnosed in clinical practice because of its nonspecific presentation. Although several techniques have been used in evaluating diaphragmatic function, the diagnosis of diaphragmatic dysfunction is still problematic. Diaphragmatic ultrasound has gained importance because of its many advantages, including the fact that it is noninvasive, does not expose patients to radiation, is widely available, provides immediate results, is highly accurate, and is repeatable at the bedside. Various authors have described ultrasound techniques to assess diaphragmatic excursion and diaphragm thickening in the zone of apposition. Recent studies have proposed standardization of the methods. This article reviews the usefulness of ultrasound for the evaluation of diaphragmatic function, addressing the details of the technique, the main findings, and the clinical applications.

Paradoxical Motion on Sniff Test Predicts Greater Improvement Following Diaphragm Plication

BACKGROUND

Diaphragm plication (DP) improves pulmonary function and quality of life for those with diaphragm paralysis or dysfunction. It is unknown whether differing degrees of diaphragm dysfunction as measured by sniff testing affect results after plication.

METHODS

Patients who underwent minimally invasive DP from 2008 to 2019 were dichotomized based on sniff test results: paradoxical motion (PM) versus no paradoxical motion (NPM); the latter included normal, decreased, and no motion. Preoperative and postoperative pulmonary function testing (PFT) after DP was compared between groups. The impact of the diaphragm height index, a measure of diaphragm elevation, was also assessed.

RESULTS

A total of 26 patients underwent preoperative sniff testing, DP, and postoperative PFT. Including all patients, DP resulted in a 17.8% ± 5.5% improvement in forced expiratory volume in 1 second (P < .001), a 14.4% ± 5.3% improvement in forced vital capacity (P < .001), and a 4.7% ± 4.6% improvement in the diffusing capacity of carbon monoxide (P = .539). There were greater improvements in the PM group (n = 16) compared with the NPM group (n = 10) for forced expiratory volume in 1 second (27.2% ± 6.0% versus 3.9% ± 6.2%; P = .017) and forced vital capacity (28.1% ± 5.3% versus -0.5% ± 3.3%; P = .001). There was no difference in the change in the diffusing capacity of carbon monoxide between groups. There were no differences between patients with PM and NPM in the postoperative course or complications. No value for diaphragm height index predicted improvement in PFT after DP.

CONCLUSIONS

Patients with PM on sniff test have dramatically greater objective improvements in pulmonary function after plication compared with those without PM. Most patients without PM do not demonstrate improvement in standard PFT. Improvements in dyspnea require additional study.

Assessment of diaphragmatic function by ultrasonography: Current approach and perspectives

This article reports the various methods used to assess diaphragmatic function by ultrasonography. The excursions of the two hemidiaphragms can be measured using two-dimensional or M-mode ultrasonography, during respiratory maneuvers such as quiet breathing, voluntary sniffing and deep inspiration. On the zone of apposition to the rib cage for both hemidiaphragms, it is possible to measure the thickness on expiration and during deep breathing to assess the percentage of thickening during inspiration. These two approaches make it possible to assess the quality of the diaphragmatic function and the diagnosis of diaphragmatic paralysis or dysfunction. These methods are particularly useful in circumstances where there is a high risk of phrenic nerve injury or in diseases affecting the contractility or the motion of the diaphragm such as neuro-muscular diseases. Recent methods such as speckle tracking imaging and ultrasound shear wave elastography should provide more detailed information for better assessment of diaphragmatic function.

Disorders of the Diaphragm

Pathologic processes that involve the central nervous system, phrenic nerve, neuromuscular junction, and skeletal muscle can impair diaphragm function. When these processes are of sufficient severity to cause diaphragm dysfunction, respiratory failure may be a consequence. This article reviews basic diaphragm anatomy and physiology and then discusses diagnostic and therapeutic approaches to disorders that result in unilateral or bilateral diaphragm dysfunction. This discussion provides a context in which disorders of the diaphragm and their implications on respiratory function can be better appreciated.

Assessing Diaphragm Function in Chest Wall and Neuromuscular Diseases

Diaphragm dysfunction is defined as the partial or complete loss of diaphragm muscle contractility. However, because the diaphragm is one of only a few skeletal muscles that is not amenable to direct examination, the tools available for the clinician to assess diaphragm function have been limited. Traditionally, measures of lung volume, inspiratory muscle strength, and radiographic techniques such as fluoroscopy have provided the major method to assess diaphragm function. Measurement of transdiaphragmatic pressure provides the most direct means of evaluating the diaphragm, but this technique is not readily available to clinicians. Diaprhragm ultrasonography is new method that allows for direct examination of the diaphragm.

Randomized comparison between interscalene and costoclavicular blocks for arthroscopic shoulder surgery

BACKGROUND

This randomized trial compared ultrasound-guided interscalene block (ISB) and costoclavicular brachial plexus block (CCB) for arthroscopic shoulder surgery. We hypothesized that CCB would provide equivalent analgesia to ISB 30 min after surgery without the risk of hemidiaphragmatic paralysis.

METHODS

All 44 patients received an ultrasound-guided block of the intermediate cervical plexus. Subsequently, they were randomized to ISB or CCB. The local anesthetic agent (20 mL of levobupivacaine 0.5% and epinephrine 5 µg/mL) and pharmacological block adjunct (4 mg of intravenous dexamethasone) were identical for all study participants. After the block performance, a blinded investigator assessed ISBs and CCBs every 5 min until 30 min using a composite scale that encompassed the sensory function of the supraclavicular nerves, the sensorimotor function of the axillary nerve and the motor function of the suprascapular nerve. A complete block was defined as one displaying a minimal score of six points (out of a maximum of eight points) at 30 min. Onset time was defined as the time required to reach the six-point minimal composite score. The blinded investigator also assessed the presence of hemidiaphragmatic paralysis at 30 min with ultrasonography.Subsequently, all patients underwent general anesthesia. Postoperatively, a blinded investigator recorded pain scores at rest at 0.5, 1, 2, 3, 6, 12, and 24 hours. Patient satisfaction at 24 hours, consumption of intraoperative and postoperative narcotics, and opioid-related side effects (eg, nausea/vomiting, pruritus) were also tabulated.

RESULTS

Both groups displayed equivalent postoperative pain scores at 0.5, 1, 2, 3, 6, 12, and 24 hours. ISB resulted in a higher incidence of hemidiaphragmatic paralysis (100% vs 0%; P < 0.001) as well as a shorter onset time (14.0 (5.0) vs 21.6 (6.4) minutes; p<0.001). However, no intergroup differences were found in terms of proportion of patients with minimal composite scores of 6 points at 30 min, intraoperative/postoperative opioid consumption, side effects, and patient satisfaction at 24 hours.

CONCLUSION

Compared to ISB, CCB results in equivalent postoperative analgesia while circumventing the risk of hemidiaphragmatic paralysis. Further confirmatory trials are required. Future studies should also investigate if CCB can provide surgical anesthesia for arthroscopic shoulder surgery.

CLINICAL TRIALS REGISTRATION

NCT03411343.

Assessment of diaphragm motion using ultrasonography in a patient with facio-scapulo-humeral dystrophy: A case report

RATIONALE

Diaphragm is the main inspiratory respiratory muscle and little is known about diaphragm ultrasound in facio-scapula-humeral muscular dystrophy, a neuromuscular disease characterized by an asymmetric skeletal muscle involvement.

PATIENT CONCERNS

Diaphragm function evaluation DIAGNOSIS:: Diaphragm muscle weakness attested by the drop of vital capacity (VC) value from sitting position (74%) to supine position (46%).

INTERVENTIONS

A diaphragm ultrasound was performed in supine position, from the anterior subcostal window OUTCOMES:: We found an opposite side to side hemi diaphragm displacement, either during sniff maneuver or during deep inspiration maneuver, showing a cranial abnormal reduced motion of the right hemi diaphragm whereas the left hemi diaphragm moved caudally.

LESSONS

Diaphragm weakness may be present with an asymmetric pattern and an opposite motion during inspiration or sniff manoeuver in facio-scapula-humeral muscular dystrophy. A future study with a systematic evaluation of a greater number of FSHD1 patients will be necessary to characterize this population.

Diaphragmatic parameters by ultrasonography for predicting weaning outcomes

Background

Diaphragmatic dysfunction remains the main cause of weaning difficulty or failure. Ultrasonographic measurement of diaphragmatic function can be used to predict the outcomes of weaning from mechanical ventilation. Our primary objective was to investigate the performance of various sonographic parameters of diaphragmatic function for predicting the success of weaning from mechanical ventilation.

Methods

We prospectively enrolled 68 adult patients requiring mechanical ventilation who were admitted to the intensive care unit from June 2013 to November 2013. The diaphragmatic inspiratory excursion, time to peak inspiratory amplitude of the diaphragm (TPIA_dia), diaphragmatic thickness (DT), DT difference (DTD), and diaphragm thickening fraction (TFdi) were determined by bedside ultrasonography performed at the end of a spontaneous breathing trial. A receiver operating characteristic curve was used for analysis.

Results

In total, 62 patients were analyzed. The mean TPIA_dia was significantly higher in the weaning success group (right, 1.27 ± 0.38 s; left, 1.14 ± 0.37 s) than in the weaning failure group (right, 0.97 ± 0.43 s; left, 0.85 ± 0.39 s) (P <  0.05). The sensitivity, specificity, positive predictive value, and negative predictive value of a TPIA_dia of > 0.8 s in predicting weaning success were 92, 46, 89, and 56%, respectively. The diaphragmatic inspiratory excursion, DTD, and TFdi were associated with reintubation within 48 h. The P values were 0.047, 0.021, and 0.028, and the areas under the receiver operating characteristic curve were 0.716, 0.805, and 0.784, respectively.

Conclusion

Among diaphragmatic parameters, TPIA_dia exhibits good performance in predicting the success of weaning from mechanical ventilation. This study demonstrated a trend toward successful use of TPIA_dia rather than diaphragmatic inspiratory excursion as a predictor of weaning from mechanical ventilation.

Electronic supplementary material

The online version of this article (10.1186/s12890-018-0739-9) contains supplementary material, which is available to authorized users.

Characteristics of the paralysed diaphragm studied by M-mode ultrasonography

BACKGROUND

M-mode ultrasonography might be useful for detecting hemidiaphragm paralysis. The objective of the present study was to describe the motion recorded by M-mode ultrasonography of both diaphragmatic leaves in patients with a pre-established diagnosis of hemidiaphragm paralysis.

METHODS

A study was conducted in 26 patients (18 men, 8 women) with unilateral diaphragmatic paralysis. They were referred to two different rehabilitation centres after thoracic surgery in 23 cases and cardiac interventional procedures in three cases. The pulmonary function tests and the study of the diaphragmatic motion using M-mode ultrasonography were recorded.

RESULTS

The pulmonary function tests showed a restrictive pattern. The M-mode ultrasonography reported either the absence of motion or a weak paradoxical (cranial) displacement (less than 0·5 cm) of the paralysed hemidiaphragm during quiet breathing. A paradoxical motion was recorded in all patients during voluntary sniffing, reaching around -1 cm. During deep breathing, a paradoxical motion at the beginning of the inspiration was observed. Thereafter, a re-establishment of the motion in the craniocaudal direction was recorded. The excursions measured on the healthy side, during quiet breathing and voluntary sniffing, were increased in patients suffering from contralateral hemidiaphragm paralysis, when compared with 170 healthy volunteers.

CONCLUSIONS

To detect diaphragmatic dysfunction in patients at risk, it would be useful to study diaphragmatic motion by M-mode ultrasonography during quiet breathing, voluntary sniffing and deep breathing.

Management of phrenic nerve palsy following cardiac surgery

Phrenic nerve palsy (PNP) is a potential complication of cardiac surgery. It may prolong ventilation and hospitalization and result in significant morbidity and mortality. The diagnosis and management of PNP following cardiac surgery is reviewed.

Diaphragmatic paralysis in obese patients in arthroscopic shoulder surgery: consequences and causes

PURPOSE

Ambulatory process in arthroscopic shoulder surgery has boomed over past decades. Some anesthetic techniques such as interscalene block (ISB) and its surrogates are associated with diaphragmatic paralysis and might compromise outpatient procedure.

HYPOTHESIS

This study aims to assess consequences of diaphragmatic paralysis in obese patients.

METHODS

This prospective observational study screened patients with body mass index (BMI) ≥ 30 kg/m² undergoing acromioplasty or supraspinatus tendon repair. Surgery was performed using brachial plexus block, and the method of brachial plexus block was left at the discretion of attending anesthesiologists. Post-operative hemidiaphragmatic paralysis was evaluated using M-mode ultrasonography and its consequences on patient ventilation were assessed: occurrence of hypoxic episode defined as oxygen saturation less than 90% (by pulse oximeter) in room air, dyspnea and failure of ambulatory procedure. Causes of diaphragmatic paralysis were also analyzed.

RESULTS

Ninety-one patients were screened, 82 patients were included in this study and 37 patients (45%) presented diaphragmatic paralysis. Compared to patients without diaphragmatic paralysis, diaphragmatic paralysis was associated with dyspnea [10 (27%) versus 1 (2%); p = 0.0019], occurrence of patients presenting at least one hypoxic episode [6 (16%) versus 1 (2%); p = 0.02] and failure of ambulatory process [10 (27%) versus 1 (2%); p = 0.009]. The combination of axillary and suprascapular nerve blocks, but also low volume ISB, was found to be protective against diaphragmatic paralysis when compared to high volume ISB [Odds ratios 0.0019 (0.001-0.026) and 0.0482 (0.008-0.27), respectively; p < 0.001].

CONCLUSION

In patients with BMI ≥ 30 kg/m² undergoing arthroscopic shoulder surgery, diaphragmatic paralysis is associated with dyspnea, occurrence of hypoxic episodes and failure of ambulatory procedure. High volume ISB and also, to a lesser extent, low volume ISB were found to be responsible for diaphragmatic paralysis.

TRIAL REGISTRY NUMBER

Registration n° 2014-202.