Transdiaphragmatic pressure

Intense inspiratory muscle work can evoke a metabolite stimulated pressor reflex, commonly referred to as the respiratory muscle metaboreflex. When completing similar relative and absolute levels of inspiratory work, females have an attenuated blood pressure response. We sought to test the hypothesis that the lower blood pressure response to the respiratory muscle metaboreflex in females is associated with a reduced sympathetic response. Healthy young (26±4 y) males (n=9) and females (n=7) completed two experimental days...

We investigated the effect of exercise intensity and tolerable duration on the development of exercise-induced diaphragm and expiratory muscle fatigue. Ten healthy adults (25 ± 5 y; 2 females) cycled to intolerance on three separate occasions: 1) 5% below critical power (<CP; heavy intensity ); 2) ~25% of the difference (Δ) between CP and peak ramp-incremental power (Δ25; severe intensity 'longer' ); and 3) ~50% Δ (Δ50; severe intensity 'shorter' ). Diaphragm and expiratory muscle fatigue were quantified as a pre- to 5 min post-exercise reduction in magnetically evoked transdiaphragmatic (Pditw ) and gastric (Pgatw ) twitch pressures, respectively...

BACKGROUND: Pre-clinical studies suggest that dyssynchronous diaphragm contractions during mechanical ventilation may cause acute diaphragm dysfunction. We aimed to describe the variability in diaphragm contractile loading conditions during mechanical ventilation and to establish whether dyssynchronous diaphragm contractions are associated with the development of impaired diaphragm dysfunction. METHODS: In patients receiving invasive mechanical ventilation for pneumonia, septic shock, acute respiratory distress syndrome, or acute brain injury, airway flow and pressure and diaphragm electrical activity (Edi) were recorded hourly around the clock for up to 7 days...

Cervical spinal cord injury impacts ventilatory and non-ventilatory functions of the diaphragm muscle (DIAm) and contributes to clinical morbidity and mortality in the afflicted population. Periodically, integrated brainstem neural circuit activity drives the DIAm to generate a markedly augmented effort or sigh-which plays an important role in preventing atelectasis and thus maintaining lung function. Across species, the general pattern of DIAm efforts during a normal sigh is variable in amplitude and the extent of post-sigh "apnea" (i...

BACKGROUND: Several bedside assessments are used to evaluate respiratory muscle function and to predict weaning from mechanical ventilation in patients on the intensive care unit. It remains unclear which assessments perform best in predicting weaning success. The primary aim of this systematic review and meta-analysis was to summarize and compare the accuracy of the following assessments to predict weaning success: maximal inspiratory (PImax) and expiratory pressures, diaphragm thickening fraction and excursion (DTF and DE), end-expiratory (Tdiee ) and end-inspiratory (Tdiei ) diaphragm thickness, airway occlusion pressure (P0...

Following the global outbreak of COVID-19, many patients have suffered from multi-system complications and long-term sequelae caused by the virus. Diaphragm dysfunction is an obscure post-COVID-19 symptom. Although a few cases of diaphragm dysfunction caused by COVID-19 infection have been reported abroad, there are no relevant reports in China. Herein, we present two cases of patients with respiratory distress after COVID-19 infection. On admission, dynamic chest radiographs revealed diaphragm dysfunction in these patients...

PURPOSE: We aimed to assess diaphragmatic function in term and preterm infants with and without history of bronchopulmonary dysplasia (BPD), before and after the application of inspiratory flow resistive loading. METHODS: Forty infants of a median (range) gestational age of 34 (25-40) weeks were studied. BPD was defined as supplemental oxygen requirement for >28 days of life. Seventeen infants were term, 17 preterm without history of BPD, and six preterm with a history of BPD...

Introduction Advanced chronic obstructive pulmonary disease (COPD) is associated with chronic hypercapnic failure. The present work aimed to comprehensively investigate inspiratory muscle function as a potential key determinant of hypercapnic respiratory failure in patients with COPD. Methods Prospective patient recruitment encompassed 61 stable subjects with COPD across different stages of respiratory failure ranging from normocapnia to isolated nighttime hypercapnia and daytime hypercapnia. Arterialized blood gas analyses and overnight transcutaneous capnometry were used for patient stratification...

Post-burn hypermetabolism remains an important clinical problem. During this phase, there is a significant loss of diaphragmatic proteins. Better understanding of respiratory muscle dynamics and potential mechanisms affecting respiratory muscle function is necessary for the development of effective therapeutic approaches. Male wistar rats were subjected to 50% total body surface area (TBSA) burns and sham injuries, and respiratory muscle function was assessed with 0, 1, 4, 7, and 14 d post-injury, including Pulmonary function, blood gas analysis, transdiaphragmatic pressure, diaphragm ultrasonography, isolated diaphragm contractility, and fatigue index...

BACKGROUND: During control mechanical ventilation (CMV), the driving pressure of the respiratory system (ΔPrs ) serves as a surrogate of transpulmonary driving pressure (ΔPlung ). Expiratory muscle activity that decreases end-expiratory lung volume may impair the validity of ΔPrs to reflect ΔPlung . This prospective observational study in patients with acute respiratory distress syndrome (ARDS) ventilated with proportional assist ventilation (PAV+), aimed to investigate: (1) the prevalence of elevated ΔPlung , (2) the ΔPrs -ΔPlung relationship, and (3) whether dynamic transpulmonary pressure (Plungsw ) and effort indices (transdiaphragmatic and respiratory muscle pressure swings) remain within safe limits...

Gastroesophageal reflux disease (GERD) is a complex entity and one of the most frequents in general population. Association of GERD with obesity is clearly defined from an epidemiological point of view, where up to 40% of patients with overweight and obesity present reflux. Most of the risk factors associated to GERD are shared and especially frequent in patients with obesity. The pathophysiology that explain this correlation is complex and multifactorial, and includes both aspects related to physiology of motility, and anatomic changes...

BACKGROUND: Gastroesophageal reflux (GER) is known to be associated with chronic lung diseases. The driving force of GER is the transdiaphragmatic pressure (Pdi) generated mainly by costal and crural diaphragm contraction. The latter also enhances the esophagogastric junction (EGJ) pressure to guard against GER. METHODS: The relationship between Pdi and EGJ pressure was determined using high resolution esophageal manometry in patients with interstitial lung disease (ILD, n = 26), obstructive lung disease (OLD, n- = 24), and healthy subjects (n = 20)...

BACKGROUND: Prophylactic high-flow nasal cannula (HFNC) oxygen therapy can decrease the risk of extubation failure. It is frequently used in the postextubation phase alone or in combination with noninvasive ventilation. However, its physiological effects in this setting have not been thoroughly investigated. The aim of this study was to determine comprehensively the effects of HFNC applied after extubation on respiratory effort, diaphragm activity, gas exchange, ventilation distribution, and cardiovascular biomarkers...

We aimed to assess the determinants of diaphragmatic function in term and preterm infants. 149 infants (56 term; 93 preterm, of whom 14 were diagnosed with bronchopulmonary dysplasia-BPD) were studied before discharge. Diaphragmatic function was assessed by measurement of the maximum transdiaphragmatic pressure (Pdimax)-a measure of diaphragmatic strength, and the pressure-time index of the diaphragm (PTIdi)-a measure of the load-to-capacity ratio of the diaphragm. The Pdimax was higher in term than preterm infants without BPD (90...

Aging results in increased neuromuscular transmission failure and denervation of the diaphragm muscle, as well as decreased force generation across a range of motor behaviors. Increased risk for respiratory complications in old age is a major health problem. Aging impairs autophagy, a tightly regulated multistep process responsible for clearing misfolded or aggregated proteins and damaged organelles. In motor neurons, aging-related autophagy impairment may contribute to deficits in neurotransmission, subsequent muscle atrophy and loss of muscle force...

The respiratory muscle pressure generation and inspiratory and expiratory neuromuscular recruitment patterns in younger and older men were compared during exercise, alongside descriptors of dyspnea. Healthy younger (n = 8, 28 ± 5 years) and older (n = 8, 68 ± 4 years) men completed a maximal incremental cycling test. Esophageal, gastric (Pga ) and transdiaphragmatic pressures, and electromyography (EMG) of the crural diaphragm were measured using a micro-transducer and EMG catheter...

INTRODUCTION AND IMPORTANCE: Subcutaneous emphysema, pneumomediastinum and pneumoperitoneum simultaneously are a rare complication of endoscopic retrograde cholangiopancreatography (ERCP) that usually indicates free perforation to the peritoneal cavity or the retroperitoneal space. CASE PRESENTATION: We report an unusual case of a subcutaneous emphysema, pneumomediastinum and pneumoperitoneum following an ERCP for removal of a common bile duct stone. There was no radiological evidence of peritoneal or retroperitoneal perforation...

INTRODUCTION: The clinical features of COVID-19 are highly variable. It has been speculated that the progression across COVID-19 may be triggered by excessive inspiratory drive activation. The aim of the present study was to assess whether the tidal swing in central venous pressure (ΔCVP) is a reliable estimate of inspiratory effort. METHODS: Thirty critically ill patients with COVID-19 ARDS underwent a PEEP trial (0-5-10 cmH2 O) during helmet CPAP. Esophageal (ΔPes) and transdiaphragmatic (ΔPdi) pressure swings were measured as indices of inspiratory effort...

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INTRODUCTION: Although the effects on hemodynamics of gasping during cardiac arrest (CA) have received a lot of attention, less is known about the respiratory mechanics and physiology of respiration in gasping. To investigate the respiratory mechanics and neural respiratory drive of gasping during cardiac arrest in a porcine model. METHOD: Pigs weighing 34.9 ± 5.7 kg were anesthetized intravenously. Ventricular fibrillation (VF) was electrically induced and untreated for 10 min...