Diaphragmatic Paralysis Research Articles

Diagnosis of diaphragmatic paralysis by ultrasound after cardiac surgery

Diagnosis of diaphragmatic paralysis by ultrasound after cardiac surgery

Phrenic-to-intercostal reflex activity in response to high frequency spinal cord stimulation (HF-SCS)

ObjectiveHF-SCS is a novel technique of inspiratory muscle activation which results in coincident activation of the diaphragm and inspiratory intercostal muscles via spinal cord pathways and has the potential to provide respiratory support in ventilator dependent persons with spinal cord injury. The purpose of the present study was to examine the phrenic-to-intercostal reflex during HF-SCS. MethodsIn 5 anesthetized and C2 spinalized dogs, electrical stimulation was applied via a stimulating electrode located on the ventral surface of the upper thoracic spinal cord at the T2 level. Fine wire recording electrodes were used to assess single motor unit (SMU) activity of the left and right external intercostal muscles (EI) in the 3rd interspace before and after sequential left and right phrenicotomy. ResultsMean control peak firing frequency of the right EI and left EI was 11.4 ± 0.3 Hz and 10.6 ± 0.3 Hz respectively. Following unilateral right phrenic nerve section, mean SMU peak firing frequency of right EI (ipsilateral to the section) was significantly greater when compared to control (15.9 ± 0.5 Hz vs 11.4 ± 0.3 Hz; p = 0.01). Mean SMU peak firing frequency of the contralateral left EI remained unchanged (10.2 ± 0.3 Hz vs 10.6 ± 0.3 Hz, p = 0.40). Subsequent, section of the left phrenic nerve resulted in significantly higher mean SMU peak firing frequency of the left EI (16.2 ± 0.5 Hz vs 10.2 ± 0.3 Hz) when compared to before section p = 0.01). Contralateral, right EI peak firing frequency was not different if compared to before left phrenic nerve section (16.9 ± 0.4 Hz vs. 15.9 ± 0.5 Hz; p = 0.14). ConclusionThis study demonstrates that during HF-SCS: 1) unilateral diaphragmatic afferents reflexly inhibit motor activity to the ipsilateral EI muscles, 2) the neural circuitry mediating the phrenic-to-intercostal reflex is preserved at a spinal level and does not require supraspinal input and 3) unilateral compensatory increases were observed in EI muscle activation following ipsilateral diaphragm paralysis.

Long-term efficacy of diaphragm plication on the pulmonary function of adult patients with diaphragm paralysis: a retrospective cohort study.

BackgroundDiaphragm plication is an effective and safe procedure for patients with symptomatic, acquired diaphragm paralysis. Improvements in dyspnea scores, ventilation perfusions and exercise capacity has been reported. Unfortunately, no continuous measurements of lung functions at 3 to 5 years’ follow-up have been recorded. This study was designed to assess the long-term effects and potential mechanism of diaphragm plication for non-malignant diaphragmatic paralysis patients, especially in relation to patients’ subjective and objective improvement.MethodsThis study retrospectively reviewed the medical records of 36 adult patients with diaphragmatic paralysis treated with diaphragm plication by thoracotomy at the Tianjin Chest Hospital from 1992 to 2016. The adult patients were carefully selected based on etiology and a combination of clinical manifestation, pulmonary function testing, and chest imaging characteristics. Patients’ preoperative pulmonary functions, forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) in the supine and sitting positions were recorded. Survival information was obtained at follow-ups continuously conducted with 8 patients for 4 years after surgery.ResultsThe main symptoms were lifestyle-limiting dyspnea and orthopnea, and a few patients also had digestive symptoms. The mean body mass index of patients was 26.02±2.19. The etiology was trauma in 3 patients, and surgery in 5 patients. The operated diaphragm was found to be lower than the contralateral diaphragm in the first 3 months after surgery; however, from the 4th month, both sides of the diaphragm were basically at the same level. Additionally, 31 patients (86.11%) showed an improvement in subjective symptoms, especially digestive symptoms preoperatively. The averages of FVC and FEV1 increased by 26.8% and 24.3%, respectively, in patients 6 months after diaphragmatic plication, and from the 18th month, lung function declined gradually, returning to preoperative levels in the 4th year.ConclusionsDiaphragmatic plication can obviously improve the lung function and subjective symptoms of patients in the short term, but from the 18th month, lung function declined gradually to preoperative levels in the 4th year indicated that its long-term effect on lung function is poor. The major purpose of diaphragmatic plication is to balance the position of the heart and abdominal organs, and thus to improve patients’ symptoms to a certain extent.

AMPK-Nrf2 Signaling Pathway in Phrenic Motoneurons following Cervical Spinal Cord Injury

High spinal cord injuries (SCI) induce the deafferentation of phrenic motoneurons, leading to permanent diaphragm paralysis. This involves secondary injury associated with pathologic and inflammatory processes at the site of injury, and at the level of phrenic motoneurons. In the present study, we evaluated the antioxidant response in phrenic motoneurons involving the AMPK-Nrf2 signaling pathway following C2 spinal cord lateral hemi-section in rats. We showed that there is an abrupt reduction in the expression of phosphorylated AMPK and Nrf2 at one hour post-injury in phrenic motoneurons. A rebound is then observed at one day post-injury, reflecting a return to homeostasis condition. In the total spinal cord around phrenic motoneurons, the increase in phosphorylated AMPK and Nrf2 occurred at three days post-injury, showing the differential antioxidant response between phrenic motoneurons and other cell types. Taken together, our results display the implication of the AMPK-Nrf2 signaling pathway in phrenic motoneurons’ response to oxidative stress following high SCI. Harnessing this AMPK-Nrf2 signaling pathway could improve the antioxidant response and help in spinal rewiring to these deafferented phrenic motoneurons to improve diaphragm activity in patients suffering high SCI.

Neurological complications in pediatric liver transplant recipients.

There is paucity of data on neurological complications (NCs) and its predisposing factors, in pediatric liver transplant (PLT) recipients. Records of seventy-one children who underwent LT between October 2018 and November 2019 were reviewed. Patients were categorized into group A: with NC and group B: without NC in the post-LT period. Various risk factors contributing to NC were studied. In total, 15 (21.1%) had NC (group A) and 56 (78.9%) had no NC in the post-LT period. NC included cerebrovascular accident (n=1), seizures (n=5; 4 generalized, 1 focal), central pontine myelolysis (CPM) (n=1), diaphragmatic palsy (n=2), peripheral neuropathy (n=1), extrapyramidal movements (n=3), and encephalopathy beyond 96 h (n=2). The median onset of NC was at 8.5 days post-LT (1-58 days). Ten (66.7%) patients in group A had grades 2-4 hepatic encephalopathy (HE) prior to LT. Eight (14.3%) patients in group B also had pre-LT neurological issues including HE in six, epilepsy and spastic diplegia in one each. On univariate analysis, pre-existing HE, high PELD/MELD score, pre-LT ventilation, pre-LT infection, higher day 1 post-operative bilirubin (all p < .05), and higher tacrolimus were found to predict post-operative NC whereas on multivariate analysis, pre-LT HE was the only predictive factor. Median follow-up was 15.5 months. Four patients died in each group (survival log-rank p=.369). All the surviving patients in group A (n=11) fully recovered from the NC. Pre-transplant HE was the single most significant predisposing factor for post-LT neurological complications.

Ultrasound imaging of diaphragmatic motion.

The diaphragm is the key muscle of respiration, especially in infants. Diaphragmatic dysfunction and paralysis can have significant implications for medical management and treatment, and they can be challenging to diagnose by clinical parameters alone. Multiple imaging modalities are useful for assessing the diaphragm, but US - specifically M-mode US - offers several distinct advantages and few limitations compared to fluoroscopy, radiography, CT and MRI. The purpose of this manuscript is to discuss the pathophysiology of the diaphragm, review common indications for dynamic diaphragmatic US, describe optimal imaging technique, and discuss how to avoid imaging pitfalls.

Bilateral brachial plexus block and avoiding its complications : A case report

Literature on bilateral brachial plexus blocks is rare as it’s seldom performed due to its complications. We present a case of a patient with anticipated difficult airway who underwent bilateral upper limb surgery where brachial plexus blocks were used as the sole mode of anaesthesia. Blocks were performed with plain 0.5% bupivacaine below its maximum safe dose under ultrasound guidance. A good postoperative 24-hour patient satisfaction was noted with no opioid consumption. Potential complications of diaphragmatic paralysis, local anaesthesia systemic toxicity and pneumothorax were mitigated with ultrasound guidance, correct patient selection, while using the knowledge on different types of brachial plexus blocks and local anaesthetic pharmacokinetics.

Antidotal treatment of botulism in rats by continuous infusion with 3,4-diaminopyridine

Botulinum neurotoxins (BoNTs) are highly potent, select agent toxins that inhibit neurotransmitter release at motor nerve terminals, causing muscle paralysis and death by asphyxiation. Other than post-exposure prophylaxis with antitoxin, the only treatment option for symptomatic botulism is intubation and supportive care until recovery, which can require weeks or longer. In previous studies, we reported the FDA-approved drug 3,4-diaminopyridine (3,4-DAP) reverses early botulism symptoms and prolongs survival in lethally intoxicated mice. However, the symptomatic benefits of 3,4-DAP are limited by its rapid clearance. Here we investigated whether 3,4-DAP could sustain symptomatic benefits throughout the full course of respiratory paralysis in lethally intoxicated rats. First, we confirmed serial injections of 3,4-DAP stabilized toxic signs and prolonged survival in rats challenged with 2.5 LD50 BoNT/A. Rebound of toxic signs and death occurred within hours after the final 3,4-DAP treatment, consistent with the short half-life of 3,4-DAP in rats. Based on these data, we next investigated whether the therapeutic benefits of 3,4-DAP could be sustained throughout the course of botulism by continuous infusion. To ensure administration of 3,4-DAP at clinically relevant doses, three infusion dose rates (0.5, 1.0 and 1.5 mg/kg∙h) were identified that produced steady-state serum levels of 3,4-DAP consistent with clinical dosing. We then compared dose-dependent effects of 3,4-DAP on toxic signs and survival in rats intoxicated with 2.5 LD50 BoNT/A. In contrast to saline vehicle, which resulted in 100% mortality, infusion of 3,4-DAP at ≥ 1.0 mg/kg∙h from 1 to 14 d after intoxication produced 94.4% survival and full resolution of toxic signs, without rebound of toxic signs after infusion was stopped. In contrast, withdrawal of 3,4-DAP infusion at 5 d resulted in re-emergence of toxic sign and death within 12 h, confirming antidotal outcomes require sustained 3,4-DAP treatment for longer than 5 d after intoxication. We exploited this novel survival model of lethal botulism to explore neurophysiological parameters of diaphragm paralysis and recovery. While neurotransmission was nearly eliminated at 5 d, neurotransmission was significantly improved at 21 d in 3,4-DAP-infused survivors, although still depressed compared to naïve rats. 3,4-DAP is the first small molecule to reverse systemic paralysis and promote survival in animal models of botulism, thereby meeting a critical treatment need that is not addressed by post-exposure prophylaxis with conventional antitoxin. These data contribute to a growing body of evidence supporting the use of 3,4-DAP to treat clinical botulism.

RIGHT SIDED DIAPHRAGMATIC EVENTRATION: A RARE CASE REPORT

Introduction: Eventration of hemidiaphragm is dened as the permanent elevation of all or part of the diaphragm, without defects of continuity in which the involved muscles of the diaphragm are being replaced partly or in full by a bro membranous sheet. Incidence of congenital eventration is 1 in 10,000. Complete and partial eventration both can occur. Complete eventration of the right hemidiaphragm with asthma in an adult female, as presented in this patient, is rarely seen. Case Presentation: A middle aged female presented with complaints of dyspnea and dry cough. Chest examination revealed decreased movements and breath sounds on right side in inframammary, infraaxillary, and infrascapular areas along with bilateral wheeze. Plain Chest radiograph followed by CT thorax was done which revealed an elevated right hemidiaphragm. Possibility of diaphragmatic eventration and paralysis was made. Later on, uoroscopic sniff test was performed. Discussion: Patients are generally asymptomatic however obese patients are usually symptomatic. Conventional chest radiography has been found to be a useful modality for assessment of the functional status of an elevated diaphragm as the evaluation of the shape of an elevated diaphragm may preclude the need for uoroscopic sniff test. However, uoroscopy is necessary to conrm between diaphragmatic paralysis and eventration. Conclusion: It is difcult to distinguish diaphragmatic eventration from paralysis clinically. In our case, diagnosis was made based on radiological ndings and conrmed by nerve conduction study. Patients are managed conservatively but symptomatic patients require surgery.

Extubation Failure in Infants with Modified Blalock-Taussig Shunt: The Incidence, Predictors, and Outcomes

Infants with congenital heart diseases often require mechanical ventilation and a prolonged intensive care unit (ICU) stay due to complex cardiopulmonary complications. The primary objective of the study was to determine the incidence and predictors of tracheal extubation failure in infants undergoing modified Blalock-Taussig shunt (MBTS). The secondary objective was to evaluate if extubation failure was associated with increased mortality and longer ICU and hospital stays. Single-center, retrospective, cohort study. Tertiary center pediatric cardiac ICU. Infants who underwent MBTS between January 2010 and December 2019. None. The demographic data and details related to the preoperative, intraoperative, and pretracheal extubation clinical conditions in the ICU were compared between the 2 study arms. Statistically significant predictors were analyzed using multivariate analysis. The p value was based on the Student's -t test for continuous variables and the chi-square test for categorical variables. A total of 146 infants were recruited for the study. Extubation failure occurred in 27 infants (18.5%), resulting in longer ICU and hospital stays. Extubation failure was deemed to be positively associated with preoperative mechanical ventilation duration, the need for escalation of the inotropic score, diaphragmatic paralysis, and systolic blood pressure ≤50th percentile at the time of extubation. The incidence rate of extubation failure after placement of MBTS was 18.5%. Preoperative mechanical ventilation, diaphragmatic paralysis, the need for escalation of the inotropic score, and systolic blood pressure ≤50th percentile could be considered predictors of extubation failure in these infants.

0378 Daytime PAP Accommodation: A Breath of Fresh Air

Abstract Introduction Rising healthcare costs and resource utilization represents a growing problem in the United States, especially for individuals with progressive neuromuscular disorders. Diagnosis and treatment of obstructive sleep apnea has been demonstrated to decrease healthcare resources in the general population; however, there is no well-defined approach to diagnosis and management of sleep-disordered breathing (SDB) in patients with neuromuscular disease (NMD). Many providers believe it best to diagnose and introduce positive airway pressure (PAP) support during a single overnight in-laboratory sleep study. Patients with NMD require a team with understanding of sleep physiology, complex pulmonary pathophysiology, disease process and progression, and advanced PAP therapy modes and indications. Optimal treatment requires patient and caregiver education, frequent monitoring of PAP data, ongoing evaluation of oxygenation and ventilation parameters, as well as assistance with device issues. We hypothesized a focused, personalized approach to managing patients with NMD will improve patient adherence to PAP therapy, nocturnal oxygenation, and ventilation, as well as limit hospital admissions. Methods 10 patients diagnosed with NMD (including muscular dystrophy, diaphragm paralysis, and scoliosis) presented to UPMC Montefiore sleep lab for daytime accommodation study with a pulmonary-sleep physician and dual-trained respiratory therapist-sleep technician. The visit included mask fitting, patient education, and initiation of PAP therapy with titration of bilevel pressure settings. Data collected included: pre- and 3-month-post nocturnal oxygen saturation and serum bicarbonate level; data download at 3 months including device usage, leak, average PAP pressures; and number of hospital admissions. Results All 10 patients demonstrated initiation of PAP therapy with usage on 100% of days for minimum of 6 hours per night. There was improvement in average nocturnal oxygen saturation and serum bicarbonate level after visit compared to prior. 3 patients were hospitalized in 6-12 months following, none for respiratory related reasons. Conclusion In this pilot study, an innovative daytime PAP accommodation study for patients with sleep-disordered breathing due to NMD results in excellent initiation and adherence to PAP therapy, as well as improvement in oxygenation and ventilation and minimal hospitalizations. Future studies are necessary including a larger randomized trial to demonstrate the safety and efficacy of home based NIV initiation. Support (If Any) NIH T32 HL082610-15, American Thoracic Society ASPIRE fellowship

Additional left atrial posterior wall ablation using pulsed field ablation as a safe and feasible treatment option for persistent atrial fibrillation patients

Abstract Funding Acknowledgements Type of funding sources: Public hospital(s). Main funding source(s): University Hospital Center Split Background Catheter ablation in persistent (PeAF), and especially long-standing persistent AF (ls-PeAF) patients often requires ablation beyond pulmonary vein isolation (PVI) (1). Adjunctive ablation of the left atrial posterior wall (LAPW) may improve outcomes of PeAF patients but has been limited by the difficulty of achieving lesion durability and concerns of thermal damage of nearby structures. Pulsed field ablation (PFA) is a new, nonthermal ablative modality, with proven myocardial ablative efficacy, quick energy delivery, and a favorable safety profile, which makes PFA suitable for the LAPW ablation (2). Purpose We aimed to report the safety profile, intraprocedural parameters, and acute success rate of LAPW ablation in a regular clinical setting with the CE-marked PFA platform. Methods This was a prospective observational study on the safety and feasibility aspects of LAPW ablation with the PFA in PeAF and ls-PeAF patients. The safety endpoints included the percentage of clinically relevant complications, including stroke/TIA, atrioesophageal fistula, cardiac tamponade, myocardial infarction, diaphragmatic paralysis, and death in the first 30-days post-procedure. Acute ablation success was confirmed with electroanatomical mapping (EAM). Ablation was performed using 2.0 kV biphasic waveforms, 2 deliveries for each application site. The lesion set depended on the patient’s AF ablation history, LA size, and anatomy. After LA mapping and PVI or PVI touch-up (index or re-do procedure), 2 anchor lesions per vein extending to the LAPW were deployed. A lesion set was then performed between the anchor lesions on the LAPW (upper and lower row) with the catheter in a flower configuration and the intention of 75% overlap for the neighbouring application sites at 3D EAM. Results Twenty-three patients (87% men) received PFA LAPW ablation. The age median was 64 (Q1-Q3: 56.5-71) years. 52% had ls-PeAF and 65% had previous ablation. The median LA diameter was 47 mm (Q1-Q3: 46-52 mm). The safety endpoints did not occur in any of the patients. The LA ablation catheter dwell time median for the index and re-do procedure was 39.5 (Q1-Q3: 31-42.25) and 18 (Q1-Q3: 16-21) minutes. The median time for LAPW ablation was 10 (Q1-Q3: 8-12) minutes. The median number of application sites on the upper and lower posterior wall was 6 (Q1-Q3: 5-7) and 6 (Q1-Q3: 5-7), respectively. Acute ablation success was 100% in terms of completed box lesion, and LAPW electrical activity loss. In a single case, first-pass ablation was not achieved, but additional delivery under intracardiac echocardiography guidance resulted in the electrical silence of the targeted segment. Conclusion LAPW ablation with PFA is safe, quick and results in excellent acute isolation rates in PeAF patients. Posterior wall ablation with PFA is not a time-consuming procedure which is an important aspect for real-world PeAF and ls-PeAF patients who are often fragile.

Minimally Invasive Diaphragm Plication for Acquired Unilateral Diaphragm Paralysis: A Systematic Review.

Objective: Diaphragm paralysis is a relatively uncommon entity that can be both congenital and acquired in nature. While commonly asymptomatic, it can also cause a significant decrease in pulmonary function and reserve, particularly in patients with underlying pulmonary diseases. Our aim was to summarize the current literature regarding the minimally invasive techniques used in the surgical correction of acquired diaphragm paralysis via traditional and robotic minimally invasive approaches. Methods: We conducted a systematic review of available literature using the Cochrane methodology and reported findings according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) standards. Results: A total of 6,561 citations were identified through initial database and reference searches, of which 90 articles met the inclusion criteria for review. After further assessment, 33 appropriate full-text studies were selected for the review. Of the selected publications, the majority represented case reports and single-center retrospective studies with level of evidence 4. Only 1 level 2b study (individual cohort study) was identified, comparing minimally invasive and open approaches. Conclusions: Each of the minimally invasive approaches has its unique benefits and disadvantages, which are summarized and delineated in this article. Ultimately, no preferred method of diaphragm plication for diaphragm paralysis can be recommended at this time based on clinical data. The choice of procedure and surgical approach continues to be selected based on the surgeon's experience and preference.

Prolonged diaphragm activation using closed loop optogenetic stimulation

Diaphragm dysfunction in individuals with late stage neuromuscular disease and cervical spinal cord injury is a substantial problem, often resulting in respiratory insufficiencies and ultimately respiratory failure. Therefore, there is a need to develop new methods that can improve diaphragm function in these clinical populations. Here we used an optogenetic method of activating diaphragm myofibers to assess the feasibility of prolonged photostimulation of the diaphragm. Our hypothesis was that closed loop photostimulation can pace the diaphragm over a prolonged period (1 hour) without a decrease in evoked response magnitude. Wild type mice (C57/bl6, n= 5) received an injection of AAV9‐CAG‐ChR2‐mVenus (34 µl, titer: 1.8x1013 vg/ml) to the intrapleural space between the lung and chest wall to target the diaphragm. After an 8‐18 week incubation period, diaphragm EMG and respiratory airflow were measured under isoflurane anesthesia. A light stimulus was delivered to the inferior diaphragm surface using a high‐power, 472 nm, micro‐LED. Photostimulation was delivered in a closed loop fashion using the onset of the inspiratory EMG burst recorded in intact hemi‐diaphragm to trigger the stimulus. The photostimulation paradigm consisted of a 250 ms, ramping/decrementing train of light pulses (pulse duration = 0.1 ms, interpulse interval = 0.1 ms). After a 10‐minute baseline recording, a unilateral right phrenicotomy was performed to paralyze the right diaphragm. The photostimulation paradigm immediately restored EMG activity to the paralyzed hemi‐diaphragm. Further, the magnitude of the evoked diaphragm EMG bursts stayed consistent over the sixty‐minute period of closed loop photostimulation, and there was no evidence of a decrement in EMG activation. Post‐mortem histology confirmed mVenus expression in diaphragm myofibers. We conclude that stimulation of the diaphragm using optogenetics is effective for up to one hour. This is a first demonstration of prolonged photostimulation of the diaphragm and provides evidence to support the feasibility of this method for the treatment of chronic diaphragm paralysis.

Effects of double vs triple injection on block dynamics for ultrasound-guided intertruncal approach to the supraclavicular brachial plexus block in patients undergoing upper limb arteriovenous access surgery: study protocol for a double-blinded, randomized controlled trial

BackgroundUltrasound-guided intertruncal approach (IA) has been proposed to be an alternative and promising approach to the supraclavicular block (SCB), in which double injection (DI) of local anesthetics (LA) is sequentially administered between intertruncal planes. We would like to apply a refined injection technique, named triple injection (TI) technique, based on the 3 separate compartments visualized by ultrasound. The aim of this study is to compare the percentage of patients with complete sensory blockade at 20 min of DI vs TI technique, when they are applied in patients undergoing upper limb arteriovenous access surgery.MethodsThis study is a prospective parallel-group randomized controlled trial. A total of 86 end-stage renal disease patients will be randomly allocated to receive IA-SCB using either DI or TI technique with identical LA (0.5% ropivacaine 24 mL). The primary outcome is the percentage of patients with complete sensory blockade of all 4 terminal nerves (median, ulnar, radial, and musculocutaneous nerves) of the brachial plexus measured at 20 min after injection. The secondary outcomes will consist of the sensory or motor blockade of all individual nerves, onset times, performance time, diaphragmatic paralysis, surgical anesthesia, and adverse events.DiscussionIt is expected that ultrasound-guided IA-SCB with the TI technique results in better block dynamic in patients undergoing upper limb arteriovenous access surgery.Trial registrationChinese Clinical Trial Registry ChiCTR2100045075.

Diaphragmatic fracture vs. phrenic paralysis after debulking surgery.

Diaphragmatic fracture vs. phrenic paralysis after debulking surgery.

The Amplitude of Diaphragm Compound Muscle Action Potential Correlates With Diaphragmatic Excursion on Ultrasound and Pulmonary Function After Supraclavicular Brachial Plexus Block.

ObjectiveThis prospective, double-blind, randomized study assessed (1) the associations between diaphragm compound muscle action potential (CMAP), hemidiaphragmatic excursion, and pulmonary function after supraclavicular brachial plexus block (SCBPB) and (2) diagnostic efficacy of pulmonary function for hemidiaphragmatic paralysis evidenced by diaphragm CMAP as an assessment of diaphragm strength was evaluated.MethodsEighty-six patients were scheduled for the removal of hardware after healing of a right upper limb fracture distal to the shoulder who were randomly assigned in a 1:1 ratio to two groups: Group A (diaphragmatic excursion), or Group B (pulmonary function). Phrenic nerve conduction studies (PNCSs), M-mode ultrasonography of the diaphragm, and pulmonary function tests (PFTs) were performed before and 30 min after SCBPB. PNCSs were used to determine the latency and amplitude of diaphragm CMAP. Ultrasonography of the diaphragm was performed with patients in a supine position using a low-frequency probe over the subcostal space at the midclavicular line. The diaphragmatic excursion was measured during quiet breathing and deep breathing. Pulmonary function, i.e., forced vital capacity (FVC), predicted value of FVC, and forced expiratory flow in the first second (FEV1), was measured with spirometry. Receiver Operating Characteristic (ROC) curve analysis was used to assess the diagnostic efficacy of pulmonary function for hemidiaphragmatic paralysis evidenced by diaphragm CMAP as an assessment of diaphragm strength.ResultsThere were significant associations between the reduction in amplitude of diaphragm CMAP and reductions in diaphragmatic excursion during quiet breathing (r = 0.70, p < 0.01) and deep breathing (r = 0.63, p < 0.01) when expressed as a percentage of baseline values. There were significant associations between the reduction in amplitude of diaphragm CMAP and reductions in FVC (r = 0.67, p < 0.01), FVC% (r = 0.67, p < 0.01), and FEV1 (r = 0.62, p < 0.01), when expressed as percentage of baseline values. The area under the ROC curve for FVC was 0.86. A decrease of >8.4% in FVC compared to pre-block predicted hemidiaphragmatic paralysis (determined by diaphragm CMAP) with sensitivity and specificity of 79.2 and 100%, respectively.ConclusionsThe relative reduction in diaphragm CMAP amplitude after SCBPB was correlated with relative reductions in diaphragmatic excursion and pulmonary function. FVC has potential as a useful diagnostic indicator of hemidiaphragmatic paralysis, evidenced by diaphragm CMAP, after SCBPB. These data establish diaphragm CMAP as a direct and objective index of diaphragmatic paralysis after SCBPB.

Effects of Chronic High-Frequency rTMS Protocol on Respiratory Neuroplasticity Following C2 Spinal Cord Hemisection in Rats.

Simple SummaryHigh spinal cord injuries (SCIs) are known to lead to permanent diaphragmatic paralysis, and to induce deleterious post-traumatic inflammatory processes following cervical spinal cord injury. We used a noninvasive therapeutic tool (repetitive transcranial magnetic stimulation (rTMS)), to harness plasticity in spared descending respiratory circuit and reduce the inflammatory processes. Briefly, the results obtained in this present study suggest that chronic high-frequency rTMS can ameliorate respiratory dysfunction and elicit neuronal plasticity with a reduction in deleterious post-traumatic inflammatory processes in the cervical spinal cord post-SCI. Thus, this therapeutic tool could be adopted and/or combined with other therapeutic interventions in order to further enhance beneficial outcomes.High spinal cord injuries (SCIs) lead to permanent diaphragmatic paralysis. The search for therapeutics to induce functional motor recovery is essential. One promising noninvasive therapeutic tool that could harness plasticity in a spared descending respiratory circuit is repetitive transcranial magnetic stimulation (rTMS). Here, we tested the effect of chronic high-frequency (10 Hz) rTMS above the cortical areas in C2 hemisected rats when applied for 7 days, 1 month, or 2 months. An increase in intact hemidiaphragm electromyogram (EMG) activity and excitability (diaphragm motor evoked potentials) was observed after 1 month of rTMS application. Interestingly, despite no real functional effects of rTMS treatment on the injured hemidiaphragm activity during eupnea, 2 months of rTMS treatment strengthened the existing crossed phrenic pathways, allowing the injured hemidiaphragm to increase its activity during the respiratory challenge (i.e., asphyxia). This effect could be explained by a strengthening of respiratory descending fibers in the ventrolateral funiculi (an increase in GAP-43 positive fibers), sustained by a reduction in inflammation in the C1–C3 spinal cord (reduction in CD68 and Iba1 labeling), and acceleration of intracellular plasticity processes in phrenic motoneurons after chronic rTMS treatment. These results suggest that chronic high-frequency rTMS can ameliorate respiratory dysfunction and elicit neuronal plasticity with a reduction in deleterious post-traumatic inflammatory processes in the cervical spinal cord post-SCI. Thus, this therapeutic tool could be adopted and/or combined with other therapeutic interventions in order to further enhance beneficial outcomes.

Abstract No. : ABS1071: Comparison of three different volumes of local anaesthetics in incidence of hemi-diaphragmatic paresis in ultrasound-guided interscalane brachial plexus block -A randomised controlled trial

Background and Aims:The incidence of diaphragmatic palsy following Interscalene brachial plexus block(IBPB) is almost 100% where the drug volume plays an indispensable role. This study compared the incidence of hemi-diaphragmatic paresis and success rate following IBPB using three different volumes of local anaesthetics(LA).Methods:Ninety patients undergoing shoulder and arm surgeries under IBPB using ultrasound were randomly allocated into three groups based on volume of LA: Group A(10ml), group B(15ml), and group C(20ml). The drug administered was 0.75% ropivacaine with 50 µg dexmedetomidine under ultrasound guidance. Diaphragm excursion was measured before and 30 minutes after the block on the side of surgery. The incidence of diaphragmatic palsy and its degree were noted. The success rate following block, the onset of sensory blockade, duration of postoperative analgesia and, adverse effects were observed in all three groups.Results:The demographic data, duration of surgery and success rate following block were statistically insignificant. Hemi-diaphragmatic paresis (<25%,25-75%,>75%) in group A(29,1,0), group B(17,13,0), and group C(15,8,7) was statistically significant (P-value<0.001)(figure 1). The difference in onset of sensory blockade in group A(7.06±0.73min), group B(6.23±0.72min) and group C(4.61±0.63min) was statistically significant with a P-value<0.001. The duration of postoperative analgesia in group A(440±48.42min) group B(429±44.48min), and group C(411±51.37min), was comparable (Pvalue-0.0719). Five patients in group C developed hoarseness of voice postoperatively which was managed conservatively.Figure 1Comparison of diaphragmatic paresis in the three groupsConclusion:Lower LA volumes in ultrasound guided interscalene block is associated with lower incidence of hemi-diaphragmatic paresis with a similar success rate and duration of postoperative analgesia. Higher volume of drug yields faster onset of the sensory blockade.

Atypical Presentation of Mixed Connective Tissue Disorder Involving Bilateral Diaphragm

Pulmonary manifestations can be present in 20-80% of patients having mixed connective tissue disorder (MCTD) and are usually subacute. MCTD when associated with polymyositis can rarely involve the diaphragm, causing respiratory failure.We present herein the case of a 49-year-old female having MCTD with a component of polymyositis who presented with bilateral diaphragmatic paralysis followed by heart failure requiring respiratory support with non-invasive mechanical ventilation. We are aware of only one prior instance of MCTD associated with unilateral diaphragmatic weakness causing mild respiratory dysfunction. To the best of our knowledge, this is the second reported case of diaphragmatic involvement in the MCTD population, with bilateral diaphragmatic paralysis causing severe respiratory failure. This is also the first reported case of such an unusual initial presentation in this patient group. Pulmonary involvement has a poor prognosis. Early diagnosis with the initiation of therapy can improve mortality outcomes in this patient population.