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Biomedical Engineering Online Jan 2023Every year, more than 2.5 million critically ill patients in the ICU are dependent on mechanical ventilation. The positive pressure in the lungs generated by the...
BACKGROUND
Every year, more than 2.5 million critically ill patients in the ICU are dependent on mechanical ventilation. The positive pressure in the lungs generated by the ventilator keeps the diaphragm passive, which can lead to a loss of myofibers within a short time. To prevent ventilator-induced diaphragmatic dysfunction (VIDD), phrenic nerve stimulation may be used.
OBJECTIVE
The goal of this study is to show the feasibility of transesophageal phrenic nerve stimulation (TEPNS). We hypothesize that selective phrenic nerve stimulation can efficiently activate the diaphragm with reduced co-stimulations.
METHODS
An in vitro study in saline solution combined with anatomical findings was performed to investigate relevant stimulation parameters such as inter-electrode spacing, range to target site, or omnidirectional vs. sectioned electrodes. Subsequently, dedicated esophageal electrodes were inserted into a pig and single stimulation pulses were delivered simultaneously with mechanical ventilation. Various stimulation sites and response parameters such as transdiaphragmatic pressure or airway flow were analyzed to establish an appropriate stimulation setting.
RESULTS
Phrenic nerve stimulation with esophageal electrodes has been demonstrated. With a current amplitude of 40 mA, similar response figures of the diaphragm activation as compared to conventional stimulation with needle electrodes at 10mA were observed. Directed electrodes best aligned with the phrenic nerve resulted in up to 16.9 % higher amplitude at the target site in vitro and up to 6 cmH20 higher transdiaphragmatic pressure in vivo as compared to omnidirectional electrodes. The activation efficiency was more sensitive to the stimulation level inside the esophagus than to the inter-electrode spacing. Most effective and selective stimulation was achieved at the level of rib 1 using sectioned electrodes 40 mm apart.
CONCLUSION
Directed transesophageal phrenic nerve stimulation with single stimuli enabled diaphragm activation. In the future, this method might keep the diaphragm active during, and even support, artificial ventilation. Meanwhile, dedicated sectioned electrodes could be integrated into gastric feeding tubes.
Topics: Animals; Swine; Phrenic Nerve; Feasibility Studies; Diaphragm; Respiration, Artificial; Electrodes; Electric Stimulation
PubMed: 36717872
DOI: 10.1186/s12938-023-01071-5 -
Journal of the American College of... Oct 2022In addition to the diaphragm's role as the primary respiratory muscle, it also plays an under-recognized role in cardiac function. It serves as a pump facilitating... (Review)
Review
In addition to the diaphragm's role as the primary respiratory muscle, it also plays an under-recognized role in cardiac function. It serves as a pump facilitating venous and lymph return, modulating left ventricular afterload hemodynamics and pericardial pressures, as well as regulating autonomic tone. Heart failure (HF) is associated with diaphragmatic changes (ie, muscle fiber atrophy and weakness, increased ratio of type I to type II muscle fibers, and altered muscle metaboreflex) that lead to diaphragmatic dysfunction with subsequent symptomatic manifestations of HF. Herein, it is proposed that targeting the diaphragm in patients with HF via inspiratory muscle training or device-based stimulation can provide a novel treatment pathway for HF. Reviewed are several potential mechanisms through which therapies targeting the diaphragm can be beneficial in HF (ie, improving preload reserve, atrial and ventricular synchrony, and metaboreflex activity; reducing pericardial restraint; and restoring diaphragm strength).
Topics: Humans; Diaphragm; Cardiovascular Diseases; Heart Failure; Hemodynamics
PubMed: 36265961
DOI: 10.1016/j.jacc.2022.08.760 -
Pain Research & Management 2022It is reported that impaired postural control in patients with non-specific chronic low back pain (NCLBP) was associated with "core" trunk muscle incoordination....
Ultrasonography Comparison of Diaphragm Morphological Structure and Function in Young and Middle-Aged Subjects with and without Non-Specific Chronic Low Back Pain: A Case-Control Study.
BACKGROUND
It is reported that impaired postural control in patients with non-specific chronic low back pain (NCLBP) was associated with "core" trunk muscle incoordination. However, as the diaphragm is an important component of the "core" deep trunk muscle group, we still know little about the potential relationship between diaphragm dysfunction and NCLBP.
OBJECTIVES
This case-control study is intended to investigate the changes of diaphragm morphological structure and function in young and middle-aged subjects with and without NCLBP by ultrasound evaluation and its possible validity in predicating the occurrence of NCLBP.
METHODS
31 subjects with NCLBP (NCLBP group) and 32 matched healthy controls (HC group) were enrolled in this study. The diaphragm thickness at the end of inspiration ( ) or expiration ( ) during deep breathing was measured through B-mode ultrasound, and the diaphragm excursion ( ) was estimated at deep breathing through M-mode ultrasound. The diaphragm thickness change rate ( ) was calculated by the formula: =( - )/ × 100%.
RESULTS
Compared with the HC group, the NCLBP group had a significant smaller degree of T ( = -3.90, < 0.001), ( = -2.79, =0.005), and ( = -2.03, =0.047). However, there was no statistical difference in between the two groups ( = -1.42, =0.161). The binary logistic regression analysis indicated that (OR = 16.038, =0.014) and (OR = 7.714, =0.004) were potential risk factors for the occurrence of NCLBP.
CONCLUSIONS
The diaphragm morphological structure and function were changed in young and middle-aged subjects with NCLBP, while the diaphragm thickness change rate ( ) and diaphragm thickness at the end of expiration ( ) may be conductive to the occurrence of NCLBP. Furthermore, these findings may suggest that abnormal diaphragm reeducation is necessary for the rehabilitation of patients with NCLBP.
Topics: Middle Aged; Humans; Low Back Pain; Case-Control Studies; Diaphragm; Muscle, Skeletal; Ultrasonography
PubMed: 36569461
DOI: 10.1155/2022/7929982 -
PloS One 2022The diaphragm changes position and respiratory excursions during postural loading. However, it is unclear how it reacts to lifting a load while breath-holding or...
OBJECTIVES
The diaphragm changes position and respiratory excursions during postural loading. However, it is unclear how it reacts to lifting a load while breath-holding or breathing with simultaneous voluntary contraction of the abdominal muscles (VCAM). This study analyzed diaphragm motion in healthy individuals during various postural-respiratory situations.
METHODS
31 healthy participants underwent examination of the diaphragm using M-mode ultrasonography, spirometry, and abdominal wall tension (AWT) measurements. All recordings were performed simultaneously during three consecutive scenarios, i.e., 1. Lifting a load without breathing; 2. Lifting a load and breathing naturally; 3. Lifting a load and breathing with simultaneous VCAM.
RESULTS
Using paired-samples t-tests, lifting a load without breathing displaced the diaphragm's expiratory position more caudally (P < .001), with no change noted in the inspiratory position (P = .373). During lifting a load breathing naturally, caudal displacement of the diaphragm's inspiratory position was presented (P < .001), with no change noted in the expiratory position (P = 0.20) compared to tidal breathing. Total diaphragm excursion was greater when loaded (P = .002). Lifting a load and breathing with VCAM demonstrated no significant changes in diaphragm position for inspiration, expiration, or total excursion compared to natural loaded breathing. For all scenarios, AWT measures were greater when lifting a load (P < .001).
CONCLUSION
In healthy individuals, caudal displacement and greater excursions of the diaphragm occurred when lifting a load. The postural function of the diaphragm is independent of its respiratory activity and is not reduced by the increase in AWT.
Topics: Diaphragm; Exhalation; Humans; Muscle Contraction; Respiration; Ultrasonography
PubMed: 36215306
DOI: 10.1371/journal.pone.0275389 -
Respiratory Physiology & Neurobiology Oct 2011Phrenic motoneurons are located in the cervical spinal cord and innervate the diaphragm muscle, the main inspiratory muscle in mammals. Similar to other skeletal... (Comparative Study)
Comparative Study Review
Phrenic motoneurons are located in the cervical spinal cord and innervate the diaphragm muscle, the main inspiratory muscle in mammals. Similar to other skeletal muscles, phrenic motoneurons and diaphragm muscle fibers form motor units which are the final element of neuromotor control. In addition to their role in sustaining ventilation, phrenic motor units are active in other non-ventilatory behaviors important for airway clearance such as coughing or sneezing. Diaphragm muscle fibers comprise all fiber types and are commonly classified based on expression of contractile proteins including myosin heavy chain isoforms. Although there are differences in contractile and fatigue properties across motor units, there is a matching of properties for the motor neuron and muscle fibers within a motor unit. Motor units are generally recruited in order such that fatigue-resistant motor units are recruited earlier and more often than more fatigable motor units. Thus, in sustaining ventilation, fatigue-resistant motor units are likely required. Based on a series of studies in cats, hamsters and rats, an orderly model of motor unit recruitment was proposed that takes into consideration the maximum forces generated by single type-identified diaphragm muscle fibers as well as the proportion of the different motor unit types. Using this model, eupnea can be accomplished by activation of only slow-twitch diaphragm motor units and only a subset of fast-twitch, fatigue-resistant units. Activation of fast-twitch fatigable motor units only becomes necessary when accomplishing tasks that require greater force generation by the diaphragm muscle, e.g., sneezing and coughing.
Topics: Animals; Diaphragm; Humans; Phrenic Nerve; Pulmonary Ventilation; Recruitment, Neurophysiological
PubMed: 21763470
DOI: 10.1016/j.resp.2011.06.028 -
American Family Physician Feb 2004Almost one half of pregnancies in the United States are unintended. Primary reasons for the high rate of unplanned pregnancy include dissatisfaction with or underuse of... (Review)
Review
Almost one half of pregnancies in the United States are unintended. Primary reasons for the high rate of unplanned pregnancy include dissatisfaction with or underuse of effective contraceptive methods and poor compliance with contraceptive methods that require daily adherence. Several effective forms of contraception have become available in the United States within the past four years. The combined hormonal vaginal ring is inserted into the vagina for three weeks and then removed; after one ring-free week, a new ring is inserted. The contraceptive patch works in much the same way as oral contraceptive pills but requires only once-weekly application by the patient. A new intrauterine system that releases levonorgestrel provides the same contraception as traditional intrauterine devices but is associated with less menorrhagia and dysmenorrhea. The intrauterine system is highly effective and carries minimal risk of pelvic inflammatory disease. In providing counseling about contraception, the physician should consider the woman's preference and determine the likelihood of adherence to the regimen. In case of contraceptive failure, emergency contraception is effective.
Topics: Contraception; Contraceptive Devices, Female; Contraceptives, Oral, Hormonal; Female; Humans
PubMed: 14989572
DOI: No ID Found -
Revue Medicale de Liege Sep 2022Intrauterine devices (IUD) are the oldest of the modern contraceptives. There are currently two types of IUDs: copper IUD (Cu-IUD) and levonorgestrel IUD (LNG-IUD). Both...
Intrauterine devices (IUD) are the oldest of the modern contraceptives. There are currently two types of IUDs: copper IUD (Cu-IUD) and levonorgestrel IUD (LNG-IUD). Both offer high contraceptive effectiveness. Although they have been used for decades, the literature still brings its share of new information on IUDs: impact on oncological risk, non-contraceptive benefits, rare adverse effects, and impact on women's well-being. In addition, Cu-DIU is recognized as the most effective emergency contraceptive and can be inserted up to 5-7 days after the at-risk sexual intercourse. Research is now looking at the effectiveness of LNG-IUD in emergency contraception. Finally, new IUD concepts are also being evaluated: they should allow a reduction in the rate of expulsion, intermenstrual and heavy menstrual bleeding, an increase in comfort and in IUDs duration of use. This article makes an update on the latest developments in terms of intrauterine contraceptives.
Topics: Contraception; Female; Humans; Intrauterine Devices, Copper; Intrauterine Devices, Medicated; Levonorgestrel
PubMed: 36082599
DOI: No ID Found -
Journal of Applied Physiology... Nov 2020Obesity is associated with bioenergetic dysfunction of peripheral muscles; however, little is known regarding the impact of obesity on the diaphragm. We hypothesized...
Obesity is associated with bioenergetic dysfunction of peripheral muscles; however, little is known regarding the impact of obesity on the diaphragm. We hypothesized that obesity would be associated with diaphragm dysfunction attributable to mitochondrial oxygen consumption and structural and ultrastructural changes. Wistar rat litters were culled to 3 pups to induce early postnatal overfeeding and consequent obesity. Control animals were obtained from unculled litters. From , diaphragm ultrasound, computed tomography, high-resolution respirometry, immunohistochemical, biomolecular, and ultrastructural histological analyses were performed. The diaphragms of obese animals, compared with those of controls, presented changes in morphology as increased thickening fraction, diaphragm excursion, and diaphragm dome height, as well as increased mitochondrial respiratory capacity coupled to ATP synthesis and maximal respiratory capacity. Fatty acid synthase gene expression was also higher in obese animals, suggesting a source of energy for the respiratory chain. Myosin heavy chain-IIA was increased, indicating shift from glycolytic toward oxidative muscle fiber profile. Diaphragm tissue also exhibited ultrastructural changes, such as compact, round, and swollen mitochondria with fainter cristae and more lysosomal bodies. Dynamin-1 expression in the diaphragm was reduced in obese rats, suggesting decreased mitochondrial fission. Furthermore, gene expressions of peroxisome γ proliferator-activated receptor coactivator-1α and superoxide dismutase-2 were lower in obese animals than in controls, which may indicate a predisposition to oxidative injury. In conclusion, in the obesity model used herein, muscle fiber phenotype was altered in a manner likely associated with increased mitochondrial respiratory capability, suggesting respiratory adaptation to increased metabolic demand. Obesity has been associated with peripheral muscle dysfunction; however, little is known about its impact on the diaphragm. In the current study, we found high oxygen consumption in diaphragm tissue and changes in muscle fiber phenotypes toward a more oxidative profile in experimental obesity.
Topics: Animals; Diaphragm; Energy Metabolism; Muscle Fibers, Skeletal; Muscle, Skeletal; Obesity; Rats; Rats, Wistar
PubMed: 32909923
DOI: 10.1152/japplphysiol.00262.2020 -
Pediatric Research Mar 2022Our aim was to summarise the current evidence and methods used to assess respiratory muscle function in the newborn, focusing on current and future potential clinical... (Review)
Review
Our aim was to summarise the current evidence and methods used to assess respiratory muscle function in the newborn, focusing on current and future potential clinical applications. The respiratory muscles undertake the work of breathing and consist mainly of the diaphragm, which in the newborn is prone to dysfunction due to lower muscle mass, flattened shape and decreased content of fatigue-resistant muscle fibres. Premature infants are prone to diaphragmatic dysfunction due to limited reserves and limited capacity to generate force and avoid fatigue. Methods to assess the respiratory muscles in the newborn include electromyography, maximal respiratory pressures, assessment for thoraco-abdominal asynchrony and composite indices, such as the pressure-time product and the tension time index. Recently, there has been significant interest and a growing body of research in assessing respiratory muscle function using bedside ultrasonography. Neurally adjusted ventilator assist is a novel ventilation mode, where the level of the respiratory support is determined by the diaphragmatic electrical activity. Prolonged mechanical ventilation, hypercapnia and hypoxia, congenital anomalies and systemic or respiratory infection can negatively impact respiratory muscle function in the newborn, while caffeine and synchronised or volume-targeted ventilation have a positive effect on respiratory muscle function compared to conventional, non-triggered or pressure-limited ventilation, respectively. IMPACT: Respiratory muscle function is impaired in prematurely born neonates and infants with congenital anomalies, such as congenital diaphragmatic hernia. Respiratory muscle function is negatively affected by prolonged ventilation and infection and positively affected by caffeine and synchronised compared to non-synchronised ventilation modes. Point-of-care diaphragmatic ultrasound and neurally adjusted ventilator assist are recent diagnostic and therapeutic technological developments with significant clinical applicability.
Topics: Caffeine; Diaphragm; Fatigue; Humans; Infant, Newborn; Respiration, Artificial; Respiratory Muscles
PubMed: 33875805
DOI: 10.1038/s41390-021-01529-z -
Reproduction, Nutrition, Development 1998Diet-induced undernutrition causes deleterious changes in the structure and function of the diaphragm muscle. Diseases associated with somatic washing cause atrophy of... (Review)
Review
Diet-induced undernutrition causes deleterious changes in the structure and function of the diaphragm muscle. Diseases associated with somatic washing cause atrophy of the respiratory muscles. In cachectic subjects, the diaphragm muscle mass and thickness are reduced in proportion to the reduction in body weight. In addition, respiratory muscle strength and endurance are reduced more dramatically than the weight loss. This finding suggests that malnutrition induces a reduction in muscular mass which is associated with a decrease in contractility. Diaphragmatic weakness may increase the risk of respiratory failure in patients with chronic obstructive pulmonary disease (COPD). The primary goal of a successful nutritional programme is to improve the diaphragm strength by correcting the mineral, electrolyte and energetic disturbances at the muscular level, the latter being responsible for the decreased contractability associated with malnutrition.
Topics: Animals; Diaphragm; Humans; Nutrition Disorders; Nutritional Status; Physical Endurance
PubMed: 9638791
DOI: 10.1051/rnd:19980204