Noninvasive Assessment of Neuromechanical Coupling and Mechanical Efficiency of Parasternal Intercostal Muscle during Inspiratory Threshold Loading

This study aims to investigate noninvasive indices of neuromechanical coupling (NMC) and mechanical efficiency (MEff) of parasternal intercostal muscles. Gold standard assessment of diaphragm NMC requires using invasive techniques, limiting the utility of this procedure. Noninvasive NMC indices of parasternal intercostal muscles can be calculated using surface mechanomyography (sMMGpara) and electromyography (sEMGpara). However, the use of sMMGpara as an inspiratory muscle mechanical output measure, and the relationships between sMMGpara, sEMGpara, and simultaneous invasive and noninvasive pressure measurements have not previously been evaluated. sEMGpara, sMMGpara, and both invasive and noninvasive measurements of pressures were recorded in twelve healthy subjects during an inspiratory loading protocol. The ratios of sMMGpara to sEMGpara, which provided muscle-specific noninvasive NMC indices of parasternal intercostal muscles, showed nonsignificant changes with increasing load, since the relationships between sMMGpara and sEMGpara were linear (R2 = 0.85 (0.75–0.9)). The ratios of mouth pressure (Pmo) to sEMGpara and sMMGpara were also proposed as noninvasive indices of parasternal intercostal muscle NMC and MEff, respectively. These indices, similar to the analogous indices calculated using invasive transdiaphragmatic and esophageal pressures, showed nonsignificant changes during threshold loading, since the relationships between Pmo and both sEMGpara (R2 = 0.84 (0.77–0.93)) and sMMGpara (R2 = 0.89 (0.85–0.91)) were linear. The proposed noninvasive NMC and MEff indices of parasternal intercostal muscles may be of potential clinical value, particularly for the regular assessment of patients with disordered respiratory mechanics using noninvasive wearable and wireless devices.

Cholinesterase in different types of the muscle tissue during the early postmortem period for diagnosis of death coming

The purpose of the research: consisted in study of postmortem regularities in the content of cholinesterasein different types of muscle tissue (MT) for improving accuracy of determination of the prescriptionof death coming PDC. Materials and methods: The activity/level of cholinesterase was determinedin homogenates of the myocardial (MMH), oesophageal (OMH), diaphragm (DMH) and intercostalmuscles (IMH)within the early PMP (3-13 hours after the coming of death) on 30 human corpses. MTwas sampled in conditions of postmortem biopsy with use of special instruments; MT homogenateswere prepared following the standard technique with subsequent determination of cholinesterase content in MT homogenates. Results and discussion: The analysis of postmortem changes in the content ofcholinesterase in MT depending upon PDC revealed that after 3 hours from the moment of death comingits highest content was in muscles of the oesophagus, the least one being in MT of the intercostal muscles(respectively, (2,717.1±37.1) and (883.5±6.2) U/g, р<0.001). Levels of cholinesterase content in MT ofthe myocardium and diaphragm were rather close, though they differed (respectively, (1,213.8±8.8) and(1,512.8±11.5) U/g, р<0.05), and occupied an intermediate place between the corresponding values of MTof the intercostal muscles and oesophagus.A common pattern for the content of cholinesterase in differenttypes of MT was characterized by a decrease of this content with an increase in PDC terms; besides, thedynamic lines of its changes, that we obtained, became basic ones for substantiating quantitative timedependencies and construction of relevant nomograms for forensic diagnosis of PDC by cholinesterase content in MT. Conclusions: It was proved that the content of cholinesterase in all MT homogenates,which we studied, changed regularly (and nonlinearly), but the initial and final levels of cholinesterasecontent differed depending upon the type of MT. Besides, the dynamics in changes of the content ofcholinesterase within the time period of 3÷13 hours from the moment of death coming differed uponthe type of MT too. Advantages of the technique consist in theintegrity of biochemical examinationof different types of MT and simplicity in interpretation of findings. The application of the nomogramtechnique for assessing PDC by cholinesterase content in MT makes it possible to improve the accuracyof diagnosis for terms of the coming of death up to 60 minutes. Bangladesh Journal of Medical Science Vol.20(1) 2021 p.95-100

Ultrasonographic assessment of parasternal intercostal muscles during mechanical ventilation

Although mechanical ventilation is a lifesaving treatment, abundant evidence indicates that its prolonged use (1 week or more) promotes respiratory muscle weakness due to both contractile dysfunction and atrophy. Along with the diaphragm, the intercostal muscles are one of the most important groups of respiratory muscles. In recent years, muscular ultrasound has become a useful bedside tool for the clinician to identify patients with respiratory muscle dysfunction related to critical illness and/or invasive mechanical ventilation. Images obtained over the course of illness can document changes in muscle dimension and can be used to estimate changes in function. Recent evidence suggests the clinical usefulness of ultrasound imaging in the assessment of intercostal muscle function. In this narrative review, we summarize the current literature on ultrasound imaging of the parasternal intercostal muscles as used to assess the extent of muscle activation and muscle weakness and its potential impact during discontinuation of mechanical ventilation. In addition, we proposed a practical flowchart based on recent evidence and experience of our group that can be applied during the weaning phase. This approach integrates multiple predictive parameters of weaning success with respiratory muscle ultrasound.

Clinicoradiological diagnosis: Cough-induced transdiaphragmatic intercostal herniation

Transdiaphragmatic intercostal herniation can occur following blunt or penetrating trauma and is usually associated with rib fractures. It is uncommon and only sporadically reported in literature. We report a case of cough-induced intercostal herniation containing large bowel, on a background of sustaining a blunt chest trauma 25 years prior to presentation. The patient was treated by reducing the hernia followed by surgical repair of the diaphragm and intercostal muscles defect. He was discharged without further complications and remained well at follow-up.

DISTRIBUTION OF TRICHINELLA LARVAE IN DIFFERENT GROUPS OF MUSCLES IN SPONTANEOUSLY INFECTED RACCOON DOGS (NYCTEREUTES PROCYONOIDES)

The problem of distribution of Trichinella larvae in transversus stripe skeletal muscles of animals is quite relevant. Literature sources present a lot of contradictory information on this issue. According to a number of authors, carnivores’, including canines’, shoulder muscles and muscles of the forelimbs, pelvis and hind limbs are the most intensely affected. Other researchers provide evidence that the highest numbers of Trichinella larvae are recorded in the muscles of the truncus and head. Furthermore, information about intensely affected muscles is of great importance for the diagnosis of trichinosis. The results of our studies showed that the highest rates of infection intensity in spontaneously infected raccoon dogs were noted in the diaphragm. Less affected were the large masseter muscle, intercostal muscles and muscles of the tongue root. Trichinella larvae were practically not found in the shoulder muscles and muscles of the forelimbs, pelvis and hind limbs. Thus, the highest number of Trichinella larvae was recorded in the muscles of the truncus and head of the spontaneously infected raccoon dogs that we studied.

Airways and alveoli

The lung is the organ of gas exchange, providing the means of transferring oxygen (O2) from the air to the blood by passive diffusion for subsequent distribution to the tissues, and of similarly removing metabolically produced carbon dioxide (CO2) from the blood, which is then exhaled to the atmosphere. The lungs are enclosed within the thoracic cavity. Inspiration is driven by contraction of the intercostal muscles and the diaphragm, which expands the ribcage in both anteroposterior and lateral dimensions, such that the pressure inside the thoracic cavity but external to the lungs is reduced to below that of the air, which is thereby drawn in. Lung diseases of many types commonly affect each of the steps involved in gas exchange, and the clinical consequences can usually be readily understood if the structure–function relationships are known.