Accessory Muscle Research Articles

Factors associated with the time to recover adequate nutrition in infants hospitalized for bronchiolitis, a French retrospective study.

Inadequate feeding is a frequent reason for hospital referring in infants with bronchiolitis and may leads to unnecessary prolonged hospitalization. Our objective was to identify the factors associated with the time to recover adequate feeding (TRAF) and the hospital length of stay (LOS) in infants hospitalized for bronchiolitis. We conducted a single-center retrospective study including infants less than 12 months hospitalized for bronchiolitis at Le Havre Hospital (France) between September 2018 and February 2021. A multivariate logistic regression model was computed to investigate the factors associated with (1) TRAF, and (2) LOS. 268 infants were included to assess the TRAF and 478 infants to assess the LOS. The median age was 3.2 months (1.6-5.4) and the sex ratio M/F was 11/20. The use of accessory muscles, nutritional support, and RR ≥70/min or <30/min or apnea are associated (OR=1.5), from virtually no association (OR=1.0) to a significant positive association (OR=2.6) with the TRAF. Intense use of accessory muscles (OR=3.9; 95% CI 1.6-10.4) and "severe" clinical condition (OR=2.8; 95% CI 1.7-4.8) at admission, O<inf>2</inf> supplementation (OR=2.0; 95% CI 1.3-3.1) were significantly related to prolonged LOS in the multivariate analysis. The clinical severity on admission may be related to the TRAF, ranging from none to significant. Other known factors such as oxygen therapy and the new clinical severity scale proposed by the latest French guidelines appeared to be related to the LOS in this work. Further studies are needed to highlight these factors.

A unique variation of a four-bellied digastric muscle named "real quadrigastric muscle": a case report and literature review.

From a topographical standpoint, the digastric muscle is key to the formation of several triangles of the neck, which are of the utmost clinical significance. Herein, we present a previously unrecognised variation of the digastric muscle: a quadrigastric muscle with two accessory bellies originating from the body and angle of the mandible and inserting to the intermediate tendon. Three new triangles are demarcated between the four bellies of the aberrant muscle. Detailed knowledge of variations of the digastric muscle, changing the borders and relationships of the topographic triangles, is paramount for radiologists and surgeons operating on the anterior region of the neck.

The association between PM2.5 concentration and the severity of acute asthmatic exacerbation in hospitalized children: A retrospective study in Chongqing, China.

Ambient PM2.5 is associated with asthma exacerbation. The association between the concentration of PM2.5 and the severity of asthma exacerbation has yet to be thoroughly clarified. The study aims to explore the association between the piror 30 days average concentration of PM2.5 and the severity of acute asthma exacerbation in hospitalized children. A total of 269 children with acute exacerbation of asthma were enrolled and divided into three groups according to the PM2.5 exposure concentrations: group 1 (PM2.5: <37.5 μg/m3 ), group 2 (PM2.5: 37.5-75 μg/m3 ), group 3 (PM2.5: ≥75 μg/m3 ), respectively. The ordered logistic regression modeling was conducted to explore the influence of daily PM2.5 concentration on the clinical severity of children's asthma exacerbation. Multiple linear regression was conducted to explore the association between the concentration of PM2.5 and the length of stay in the hospital (LOS). We also conducted a receiver operating characteristic (ROC) curve analysis to explore the cutoff value of PM2.5 to predict the children's asthma exacerbation. There was no statistical difference among the three groups of children in gender, age, body mass index, ethnicity, the first diagnosis of asthma, allergic history, passive smoke exposure, or family history of asthma. There was a statistically significant difference in many hospitalization characteristics (p < 0.05) among the three groups of children. Significant differences were found in terms of accessory muscles of respiration (p = 0.005), respiratory failure (p = 0.012), low respiratory tract infectious (p = 0.020), and the severity of asthma exacerbation (p < 0.001) among the three groups. PM2.5 concentration was primarily positively correlated to neutrophile inflammation. The ordered multivariate logistic regression model showed that higher PM2.5 concentrations were significantly associated with greater odds of more severe asthma exacerbation in one and two-pollutant models. The adjusted odds ratio of severe asthma exacerbation was 1.029 (1.009, 1.049) in the one-pollutant model. The most significant odds ratio of severe asthma exacerbation was 1.050 (1.027, 1.073) when controlling NO2 in the two-pollutant models. Multiple linear regression showed that PM2.5 concentration was significantly associated with longer LOS in both one-pollutant and two-pollutant models. By performing ROC analysis, the average daily concentration of 44.5 µg/m3 of PM2.5 (AUC = 0.622, p = 0.002) provided the best performance to predict severe asthma of children exacerbation with a sensitivity of 59.2% and a specificity of 63.8%. The increased prior 30 days average concentration of PM2.5 was associated with greater asthma exacerbation severity and longer length of stay in the hospital of children with asthma exacerbation.

Expanding the repertoire of intermuscular coordination patterns and modulating intermuscular connectivity in stroke-affected upper extremity through electromyogram-guided training: a pilot study.

Abnormal intermuscular coordination is a major stroke-induced functional motor impairment in the upper extremity (UE). Previous studies have computationally identified the abnormalities in the intermuscular coordination in the stroke-affected UE and their negative impacts on motor outputs. Therefore, targeting the aberrant muscle synergies has the potential as an effective approach for stroke rehabilitation. Recently, we verified the modifiability of the naturally expressed muscle synergies of young able-bodied adults in UE through an electromyographic (EMG) signal-guided exercise protocol. This study tested if an EMG-guided exercise will induce new muscle synergies, alter the associated intermuscular connectivity, and improve UE motor outcome in stroke-affected UE with moderate-to-severe motor impairment. The study used the six-week isometric EMG signal-guided exercise protocol that focused on independently activating two specific muscles, the biceps and brachioradialis, to develop new muscle activation groups. The study found that both the stroke and age-matched, able-bodied groups were able to develop new muscle coordination patterns through the exercise while habitual muscle activation was still available, which led to improvements in the motor control of the trained arm. In addition, the results provided preliminary evidence of increased intermuscular connectivity between targeted muscles in the beta-band frequencies for stroke patients after training, suggesting a modulation of the common neural drive. These findings suggest that our isometric exercise protocol has the potential to improve stroke survivors' performance of UE in their activities in daily lives (ADLs) and, ultimately, their quality of life through expanding their repertoire of intermuscular coordination.Clinical Relevance- This study shows the feasibility of expanding the intermuscular coordination pattern in stroke-affected UE through an isometric EMG-guided exercise which positively affects task performance and intermuscular connectivity.

PENATALAKSANAAN FISIOTERAPI PADA KASUS SINDROM OBSTRUKSI PASCA TUBERKULOSIS PARU : STUDI KASUS

Introduction : Tuberculosis is a pathological condition caused by the bacterium Mycobacterium tuberculosis. Even though it has been treated, sometimes pulmonary TB cases still leave sequelae called TB sequelae. Improper management of TB sequelae can increase the risk of mortality. Thus, it is necessary to have a structured rehabilitation program in cases of TB sequelae.&#x0D; Purpose : to determine the effect of physical therapy exercise on the management of TB sequelae cases.&#x0D; Methods : Research method using a case report.&#x0D; Outcome measurement: measurement of sputum using auscultation, muscle spasm using palpation, examination of lung volume capacity using Voldyne and peak flow meter, examination of thoracic cage expansion using the midline.&#x0D; Results: after 5 times of therapy, there was decreasing sputum volume, decreasing spasm of the accessory muscles of breathing, improve thoracic expansion, and improve lung volume capacity.&#x0D; Conclusions: Administration of programmed exercise in cases of TB sequelae can increase lung volume and increase thoracic expansion.

Sudden cardiac death of a 16-year-old boy with Wolff-Parkinson-White syndrome and hypertrophic cardiomyopathy

AbstractIn Europe, 350,000 people die suddenly and unexpectedly every year. The majority of sudden deaths are caused by cardiac alterations and known as sudden cardiac death (SCD). The interpretation of medicolegal findings is especially difficult in those SCDs where there is no morphological correlate and no antemortem electrocardiograms or relevant medical history are available. The Wolff-Parkinson-White (WPW) syndrome, in which an accessory electrical conduction pathway exists between the atrium and the ventricle in addition to the physiological conduction system, is mostly a benign disease of the heart, which may lead to cardiac arrhythmia. A 16-year-old boy with a known history of WPW syndrome since the second year of life had consumed alcohol before death and was found sitting on the toilet fully dressed. The autopsy performed on the deceased 3 days postmortem showed a marked mass increase of the heart with left ventricular concentric hypertrophy and macroscopic signs of cardiomyopathy. In the microscopic examination, the right and left ventricles and the atria were found to have a regular structure with normal vessels. Hematoxylin-eosin (HE) and elastica-van-Gieson (EvG) staining disclosed a thin accessory muscle bridge connecting the left atrium with the left ventricle as a possible morphological correlate of a fatal cardiac arrhythmia.

Accessory Muscles Associated With the Levator Palpebrae Superioris Muscle in 100 Cadavers.

This study aimed to determine the variations of the levator palpebrae superioris muscle and to reveal its morphological features. This study conducted on 100 adult orbit cadavers in the Department of Anatomy, Istanbul University, used an exploratory, descriptive research design. The anatomical and morphological variations of the levator palpebrae superioris muscle and its relationship with the superior ophthalmic vein were evaluated. Variations of levator palpebrae superioris muscle were discovered in 11 of 100 orbits. Single (9%), double (1%), and triple (1%) accessory muscle slips were observed. The origin of accessory muscle slips showed variation as the accessory muscle slips originated either from the proximal or distal half of the levator palpebrae superioris muscle. Also, the insertions of accessory muscle slips were variable, as they were inserted into levator aponeurosis, trochlea, lacrimal gland, lateral orbital wall, or the fascia of the superior ophthalmic vein. Accessory muscles associated with levator aponeurosis were found in a significant proportion of cadavers. These muscles may cause confusion in orbital surgery and should be taken into account during surgical planning and orientation in the superior orbit.

Bronchiolitis and its Different Ways of Management in Raparin Teaching Hospital, Erbil-Iraq

Background: Despite the prevalence, global impact, financial burden, and mortality and morbidity related to bronchiolitis, clinical management still seems to be difficult.&#x0D; Objective: To describe the diversity medical treatment options used to manage bronchiolitis and conclude the safest and most effective way to treat it in order to help the development of an evidence based treatment protocol at Raparin teaching hospital.&#x0D; Patients and Methods: This current study design was randomized controlled trial, in which total of 125 children presented with bronchiolitis enrolled in our study, we divided them into five groups (A, B, C, D and E), each of 25 cases. All the groups received supportive treatment in the form of oxygen and intravenous (IV) fluid in addition to specific treatment except group A subjects who received supportive treatment only. The treatments were The study was conducted at the inpatient wards of Raparin teaching hospital in Erbil city-Iraq, from the period of 1st January to 1st August 2022. The infants and children’s age was ranging from 1 to 60 months with clinical diagnosis of bronchiolitis.&#x0D; Results: There was non-significant statistical association between treatment groups and presence of wheeze after treatment (p:0.538), while statistically significant association between various treatment modalities (groups) and cough after treatment (p:0.006) in the same way the association was significant with accessory muscle use after treatment (p:0.037). &#x0D; Conclusion: Generally patients in groups B (inhaled bronchodilator) and D (inhaled bronchodilator and intravenous steroids) had better response rates in terms of cough, accessory muscle use, respiratory rate (tachypnea), time to resolution of fever and coryza, duration of IV fluid therapy, oxygen therapy and hospital stay. Which conclude using of inhaled bronchodilator and IV steroid

Bronchiolitis and its Different Ways of Management in Raparin Teaching Hospital, Erbil-Iraq

Background: Despite the prevalence, global impact, financial burden, and mortality and morbidity related to bronchiolitis, clinical management still seems to be difficult. Objective: To describe the diversity medical treatment options used to manage bronchiolitis and conclude the safest and most effective way to treat it in order to help the development of an evidence based treatment protocol at Raparin teaching hospital. Patients and Methods: This current study design was randomized controlled trial, in which total of 125 children presented with bronchiolitis enrolled in our study, we divided them into five groups (A, B, C, D and E), each of 25 cases. All the groups received supportive treatment in the form of oxygen and intravenous (IV) fluid in addition to specific treatment except group A subjects who received supportive treatment only. The treatments were The study was conducted at the inpatient wards of Raparin teaching hospital in Erbil city-Iraq, from the period of 1st January to 1st August 2022. The infants and children’s age was ranging from 1 to 60 months with clinical diagnosis of bronchiolitis. Results: There was non-significant statistical association between treatment groups and presence of wheeze after treatment (p:0.538), while statistically significant association between various treatment modalities (groups) and cough after treatment (p:0.006) in the same way the association was significant with accessory muscle use after treatment (p:0.037). Conclusion: Generally patients in groups B (inhaled bronchodilator) and D (inhaled bronchodilator and intravenous steroids) had better response rates in terms of cough, accessory muscle use, respiratory rate (tachypnea), time to resolution of fever and coryza, duration of IV fluid therapy, oxygen therapy and hospital stay. Which conclude using of inhaled bronchodilator and IV steroid Keywords: Bronchiolitis, Wheeze, Treatment, Randomized clinical trial, Iraq

복장목뿔근에 대한 수동신장운동이 폐 기능에 미치는 영향

Purpose: This study aimed to investigate the effects of passive stretching exercise for the sternohyoid muscle, widely known as the accessory respiratory muscle, on pulmonary function. Methods: A total of 24 female university students without neurological, musculoskeletal, or cardiopulmonary dysfunction were included in this study. The subjects were randomly assigned to experimental (n=14) and control groups (n=10). Pulmonary function was assessed before and after passive stretching exercises using a spirometer (Pony FX, COSMED Inc., Rome, Italy). The experimental group performed 10 sets of three repetitions of passive stretching exercises for the sternohyoid muscle. The control group did not perform any exercise. Results: No significant changes in forced vital capacity and forced expiratory volume in one second were observed in both groups. However, a significant improvement in tidal volume, inspiratory capacity, and vital capacity (VC) was observed in the experimental group after passive stretching exercises, whereas no change was observed in the control group. Additionally, a significant improvement in maximal voluntary ventilation (MVV) was observed in the experimental group, whereas no change was observed in the control group. The changes in VC and MVV were higher in the experimental group than in the control group. Conclusion: Passive stretching exercises for the sternohyoid muscle can improve pulmonary function. In particular, they are effective in improving VC and MVV.

The unilateral muscular slip of the two-bellied Serratus Posterior Inferior muscle: a case report and a review of literature.

The two-bellied serratus posterior inferior (SPI) muscle with a muscular slip is a rare variation of the back region, which can cause significant discomfort to patients. Patients typically present with symptoms of chronic pain syndrome, radiating back pain, myofascial pain, or lower back pain. This report describes a case of a female cadaver with a two-headed SPI muscle and a right muscular slip, along with a literature review. A case of an unusual back muscle was observed in a female cadaver during advanced cadaver dissection of the back region. The SPI muscle was found deep to the latissimus dorsi muscle and superficial to the erector spinae and thoracolumbar fascia. Its oblique arrangement and insertion onto the 8th-11th costae were consistent with its known anatomy, but the presence of two separate fibrotendinous heads and an uncommon variance between the erector spinae and latissimus dorsi muscles was observed. The SPI muscle fibers were found to be attached to the 8th costa on the right side and displayed two heads on both sides. In our study, the presence of muscular and tendinous digitations towards the twelfth rib was not detected, which aligns with the characteristics described for types D and E. However, we observed a separation between the digitations. Therefore, it is appropriate to classify our findings as type E according to the established categorization. Simultaneously, an anomalous muscular slip, which did not conform to any of the aforementioned classifications, was identified as extending towards the 8th rib. The underlying cause of unilateral oblique muscular fiber extension is thought to result from aberrant muscle migration during embryonic development or alterations in tendon attachment sites. Differential diagnosis of unidentified lower back pain should consider the various types and alterations of the SPI muscle.

Microbes, metabolites and muscle: Is the gut-muscle axis a plausible therapeutic target in Duchenne muscular dystrophy?

What is the topic of this review? The contribution of gut microbial signalling to skeletal muscle maintenance and development and identification of potential therapeutic targets in progressive muscledegenerative diseases such as Duchenne muscular dystrophy. What advances does it highlight? Gut microbe-derived metabolites are multifaceted signalling molecules key to muscle function, modifying pathways contributing to skeletal muscle wasting, making them a plausible target for adjunctive therapy in muscular dystrophy. Skeletal muscle is the largest metabolic organ making up ∼50% of body mass. Because skeletal muscle has both metabolic and endocrine properties, it can manipulate the microbial populations within the gut. In return, microbes exert considerable influence on skeletal muscle via numerous signalling pathways. Gut bacteria produce metabolites (i.e., short chain fatty acids, secondary bile acids and neurotransmitter substrates) that act as fuel sources and modulators of inflammation, influencing host muscle development, growth and maintenance. The reciprocal interactions between microbes, metabolites and muscle establish a bidirectional gut-muscle axis. The muscular dystrophies constitute a broad range of disorders with varying disabilities. In the profoundly debilitating monogenic disorder Duchenne muscular dystrophy (DMD), skeletal muscle undergoes a reduction in muscle regenerative capacity leading to progressive muscle wasting, resulting in fibrotic remodelling and adipose infiltration. The loss of respiratory muscle in DMD culminates in respiratory insufficiency and eventually premature death. The pathways contributing to aberrant muscle remodelling are potentially modulated by gut microbial metabolites, thus making them plausible targets for pre- and probiotic supplementation. Prednisone, the gold standard therapy for DMD, drives gut dysbiosis, inducing a pro-inflammatory phenotype and leaky gut barrier contributing to several of the well-known side effects associated with chronic glucocorticoid treatment. Several studies have observed that gut microbial supplementation or transplantation exerts positive effects on muscle, including mitigating the side effects of prednisone. There is growing evidence in support of the potential for an adjunctive microbiota-directed regimen designed to optimise gut-muscle axis signalling, which could alleviate muscle wasting in DMD.

Accessory Subscapularis muscle compressing posterior division of upper trunk: A rare presentation

Presence of additional or accessory muscles near the axilla can lead to compression of vital structures of the axilla. Opposite conventional thoughts, it seems that the subscapularis muscle (SM) is the most variable muscle of the rotator cuff group. Accessory Subscapularis muscle is one of the rare variants of the Subscapularis muscle. Presence of this variant (ASsm) can cause abnormal clinical presentation. During routine dissection of the axilla in a female cadaver in the Department of Anatomy, Muzaffarnagar Medical College, we found an additional slip or accessory subscapularis muscle, arising from the anterolateral part of the Subscapularis and running upward and medially, finally attached to the coracoid process (palpated tip). During its course, it passed through the Brachial plexus and caused compression of the posterior division of the Upper trunk. This type of accessory slip or accessory subscapular muscle can cause compression neuropathy, or this accessory slip can be used during the repair of a ruptured Subscapularis or any other adjacent muscle. Keywords: Accessory Subscapularis Muscle, Rotator Cuff Variants, Brachial Plexus Compression

Primary and Accessory Respiratory Muscles and Description about Thoracic Lid, Diaphragm, Surfactant, Compliance and Stiffness of Lungs

Primary and Accessory Respiratory Muscles and Description about Thoracic Lid, Diaphragm, Surfactant, Compliance and Stiffness of Lungs

Efficacy of apraclonidine eye drops in treating ptosis secondary to myasthenia gravis: A pilot clinical trial.

Most patients with myasthenia gravis (MG) develop ocular manifestations during their illness and up to 22% may have isolated ocular myasthenia gravis (OMG). Apraclonidine elevates the eyelid by activating alpha-2 receptors on Muller's muscle, an accessory eyelid elevator muscle. In this study we evaluate the effect of apraclonidine in alleviating ptosis secondary to MG. This clinical trial (NCT05045248) was done at the American University of Beirut Medical Center. Patients with ptosis secondary to MG were administered two drops of apraclonidine 0.5% solution to the most affected eye. We measured palpebral fissure height (PF), marginal reflex distance-1 (MRD1), marginal reflex distance-2 (MRD2), and levator function (LF) before drug administration and at 1, 5, 30, and 60 minutes after administration. Ten participants were enrolled in the study. Improvement in all eyelid measurements was noted in all participants as early as 1 minute after apraclonidine administration. From baseline to 60 minutes after administration, average PF increased from 8.8 ± 1.9 mm to 14.2 ± 2.6 mm, MRD-1 from 1.7 ± 1.4 mm to 5.4 ± 2.9 mm, MRD-2 from 7.1 ± 1.3 mm to 8.8 ± 1.7 mm, and LF from 13.4 ± 2.9 mm to 17.5 ± 2.4 mm. All increases were statistically significant. Apraclonidine may alleviate ptosis secondary to MG and may be an effective alternative treatment for this group of patients.

Genomic and Epigenetic Changes Drive Aberrant Skeletal Muscle Differentiation in Rhabdomyosarcoma

Rhabdomyosarcoma (RMS), the most common soft-tissue sarcoma in children and adolescents, represents an aberrant form of skeletal muscle differentiation. Both skeletal muscle development, as well as regeneration of adult skeletal muscle are governed by members of the myogenic family of regulatory transcription factors (MRFs), which are deployed in a highly controlled, multi-step, bidirectional process. Many aspects of this complex process are deregulated in RMS and contribute to tumorigenesis. Interconnected loops of super-enhancers, called core regulatory circuitries (CRCs), define aberrant muscle differentiation in RMS cells. The transcriptional regulation of MRF expression/activity takes a central role in the CRCs active in skeletal muscle and RMS. In PAX3::FOXO1 fusion-positive (PF+) RMS, CRCs maintain expression of the disease-driving fusion oncogene. Recent single-cell studies have revealed hierarchically organized subsets of cells within the RMS cell pool, which recapitulate developmental myogenesis and appear to drive malignancy. There is a large interest in exploiting the causes of aberrant muscle development in RMS to allow for terminal differentiation as a therapeutic strategy, for example, by interrupting MEK/ERK signaling or by interfering with the epigenetic machinery controlling CRCs. In this review, we provide an overview of the genetic and epigenetic framework of abnormal muscle differentiation in RMS, as it provides insights into fundamental mechanisms of RMS malignancy, its remarkable phenotypic diversity and, ultimately, opportunities for therapeutic intervention.

Effects of high-intensity inspiratory muscle warm-up on inspiratory muscle strength and accessory inspiratory muscle activity

This study aimed to determine the effects of work-matched moderate-intensity and high-intensity inspiratory muscle warm-up (IMW) on inspiratory muscle strength and accessory inspiratory muscle activity. Eleven healthy men performed three IMWs at different intensities, namely, placebo, moderate-intensity, and high-intensity, set, respectively, at 15 %, 40 %, and 80 % of maximal inspiratory mouth pressure (MIP). MIP was measured before and after IMW. Electromyography (EMG) was recorded for the sternocleidomastoid muscle (SCM) and intercostal muscles (IC) during IMW. MIP increased significantly in the moderate-intensity condition (104.2 ± 5.1 %, p < 0.05) and high-intensity condition (106.5 ± 6.2 %, p < 0.01) after IMW. The EMG amplitudes of the SCM and IC during IMW were significantly higher in the order of high-intensity, moderate-intensity, and placebo conditions. There was a significant correlation between changes in MIP and EMG amplitude of the SCM (r = 0.60, p < 0.01) and IC (r = 0.47, p < 0.01) during IMW. These findings suggest that high-intensity IMW increases neuromuscular activity in the accessory inspiratory muscles, which may improve inspiratory muscle strength.

Fentanyl induced disruption of the coordinated reciprocal activity of inspiratory and expiratory respiratory muscles

Opioid induced respiratory depression (OIRD) occurs when respiratory pump and/or airway muscle activity are reduced ostensibly due to reduced output from the brainstem respiratory control system, resulting in central (CA) and/or obstructive apnea (OA) and reduced breathing frequency. Although less commonly reported in the literature, ORID may also result from an inappropriate activation of accessory muscles leading to the “Wooden Chest Syndrome” (WCS) -when airflow is limited due to simultaneous activation of inspiratory and expiratory pump and/or airway respiratory muscles to decrease chest wall compliance and inappropriately increase airway resistance. This phenomenon is difficult to directly study in humans, but here we present data from our large animal model (adult female goats). We tested the hypothesis that IV fentanyl would lead to transient dysfunction in respiratory accessory muscles indicative of WCS. We surgically instrumented goats (n=7) with electromyographic (EMG) wires in inspiratory (diaphragm; DIA) and expiratory (Transversus Abdominus; TA) pump muscles, as well as airway dilator (Thyropharyngeus; Thy) and constrictor (Genioglossus; GG) muscles. After &gt;2 weeks of surgical recovery, responses to saline or various doses of fentanyl citrate (25-125 mcg/kg; IV) were tested for 30 min before and up to 90 min after injection. As described in an adjacent poster, particularly over the first several minutes after fentanyl injection, CA and OA were observed in some goats. However, disruption of airflow was primarily associated with increased simultaneous activation of pump and airway inspiratory and expiratory muscles resembling WCS. For most muscles, the rate of rise in muscle activity (an index of firing intensity) increased within 2 minutes following fentanyl injection and remained significantly (P&lt;0.05) elevated up to 90 minutes. During WCS periods, airflow was oscillatory or interrupted suggesting transient closure of the airway. In addition, there were time- and dose-dependent effects on frequency, duration, and total activity of the pump and airway muscles. By 60 minutes post-injection, there were periods of transient return of muscle activity and airflow to at or below baseline values. There was no significant effect of saline on muscle activity. Overall, these data suggest that following fentanyl injection in awake goats, there was an increase in firing of pump and airway muscles which ultimately disrupts the coordinated reciprocal activity of inspiratory and expiratory muscles and contributes to OIRD. Supported by NIH DA050571 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Obligatory and accessory respiratory muscle physiology in advanced dystrophic disease

Duchenne muscular dystrophy (DMD) is a genetic neuromuscular disorder, characterized by severe and progressive skeletal muscle weakness, which extends to the respiratory muscles. We have determined that ventilatory capacity and peak inspiratory pressure-generating capacity are preserved in early dystrophic disease in the mdx mouse model of muscular dystrophy, despite profound diaphragm muscle weakness and reduced peak diaphragm electromyogram (EMG) activitya, thus revealing a capacity for compensation afforded by extra-diaphragmatic muscles of breathing. We hypothesise that peak inspiratory pressure-generating capacity is impaired in advanced dystrophic disease in mdx mice, due to loss of compensation afforded by accessory respiratory muscles.Inspiratory pressure-generating capacity and obligatory and accessory respiratory muscle structure were examined in male wild-type and mdx mice in early (4 month old) and advanced (16 month old) dystrophic disease. Inspiratory pressure was recorded in urethane (1.7g/kg i.p.) anaesthetised, spontaneously breathing mice during baseline and sustained tracheal occlusion (maximal muscle activation). Histology and immunofluorescence were used to assess the form of obligatory (diaphragm and parasternal) and accessory (sternomastoid and cleidomastoid) respiratory muscles.Our study revealed preserved peak inspiratory pressure generating capacity in early dystrophic disease. Peak inspiratory pressure generating capacity is impaired in advanced dystrophic disease. We reason that this is due to the loss of compensation afforded by accessory respiratory muscles. The relative area of collagen deposition (fibrosis) is significantly increased in mdx obligatory and accessory respiratory muscles in early dystrophic disease. The relative area of collagen deposition in mdx obligatory and accessory respiratory muscles increased with disease progression, but interestingly the increase was most pronounced in the diaphragm muscle. Myofibre remodelling is evident in mdx diaphragm muscle, but not extra-diaphragmatic muscles in early dystrophic disease. Mean minimal Feret’s diameter is reduced (relative atrophy) in all muscles in advanced dystrophic disease.Following characterisation of respiratory system performance and obligatory and accessory muscle physiology in early dystrophic disease, studies are now being extended to assess ventilatory capacity and obligatory and accessory respiratory muscle contractile function and EMG activities in advanced dystrophic disease. Characterisation of the fundamental control of breathing in mdx mice should provide a comprehensive vista of the disease, potentially revealing novel therapeutic targets. References a Burns DP, Murphy KH, Lucking EF, O'Halloran KD. Inspiratory pressure-generating capacity is preserved during ventilatory and non-ventilatory behaviours in young dystrophic mdx mice despite profound diaphragm muscle weakness. J. Physiol. 2019;597(3):831-848. Eli Lilly &amp; Science Foundation Ireland (19/FFP/6628). This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Neuromuscular coupling of obligatory respiratory muscles to inspiratory pressure is reduced in dystrophic (mdx) mice

Neuromuscular coupling (NMC) is a recognised clinical index of inspiratory muscle function which reflects the efficiency of conversion of neural activation to inspiratory pressure. Duchenne muscular dystrophy (DMD) is characterised by respiratory insufficiency culminating in respiratory failure. We investigated inspiratory pressure generating capacity and electrical activation of obligatory inspiratory muscles in X-linked muscular dystrophy ( mdx) mice, to evaluate NMC of diaphragm, external intercostal and parasternal intercostal to inspiratory pressure across a range of behaviours in early established to late progressive disease.In urethane anaesthetised mice (1.7 g/kg i.p.), inspiratory pressure was recorded via a pressure transducer positioned in the thoracic oesophagus. Diaphragm EMG activity was recorded using needle electrodes. Studies were performed in male wildtype (WT) and mdx mice at 4, 8, 12 and 16 months old. Recordings were made at baseline and during sustained tracheal occlusion to task failure, defined as an inability to sustain peak pressure. Peak pressure was determined from the average of five successive peak efforts at the maximum response. The corresponding peak inspiratory EMG activities were determined. Two factor (age x genotype) analysis of variance was performed.Obligatory muscle EMG activities were significantly lower in mdx mice from 4 months of age. Peak inspiratory pressure was significantly greater in mdx at 4 months of age. At 8 months, peak inspiratory pressure was equivalent between WT and mdx followed by a significant decrease in peak inspiratory pressure in 12- and 16-month-old mdx. NMC was lower in mdx mice across the ventilatory and non-ventilatory range, emerging early in dystrophic disease.Reduced NMC of obligatory muscles to inspiratory pressure in mdx mice reveals a greater reliance on accessory muscles to support respiratory performance in dystrophic disease. Remarkably, this burden is adequately accommodated in early disease with a preserved capacity to generate peak inspiratory pressure. We reason that the loss of compensation afforded by accessory muscles to peak inspiratory pressure generation underpins the emergence of respiratory compromise in advanced disease. Our results may have implications for the understanding and treatment of DMD. Funded by Science Foundation Ireland SFI/19/6628 INSPIRE DMD. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.