Ventilatory drive

An adequate supply of O2 is essential for the maintenance of cellular activity. Systemic or local hypoxia can be experienced during decreased O2 availability or associated with diseases, or a combination of both. Exposure to hypoxia triggers adjustments in multiple physiological systems in the body to generate appropriate homeostatic responses. However, with significant reductions in the arterial partial pressure of O2 , hypoxia can be life-threatening and cause maladaptive changes or cell damage and death...

Application of positive end-expiratory pressure (PEEP) targeted towards improving oxygenation is one of the components of the ventilatory management of pediatric acute respiratory distress syndrome (PARDS). Low end-expiratory airway pressures cause repetitive opening and closure of unstable alveoli, leading to surfactant dysfunction and parenchymal shear injury. Consequently, there is less lung volume available for tidal ventilation when there are atelectatic lung regions. This will increase lung strain in aerated lung areas to which the tidal volume is preferentially distributed...

BACKGROUND: Venovenous extracorporeal membrane oxygenation (VV-ECMO) has been demonstrated to be effective in treating patients with virus-induced acute respiratory distress syndrome (ARDS). However, whether the management of ECMO is different in treating H1N1 influenza and coronavirus disease 2019 (COVID-19)-associated ARDS patients remains unknown. METHODS: This is a retrospective cohort study. We included 12 VV-ECMO-supported COVID-19 patients admitted to The First Affiliated Hospital of Guangzhou Medical University, Guangzhou Eighth People's Hospital, and Wuhan Union Hospital West Campus between January 23 and March 31, 2020...

INTRODUCTION: There are few scores for mortality prediction in acute respiratory distress syndrome (ARDS) incorporating comprehensive ventilatory, acute physiological, organ dysfunction, oxygenation, and nutritional parameters. This study aims to determine the risk factors of ARDS mortality from the above-mentioned parameters at 48 h of invasive mechanical ventilation (IMV), which are feasible across most intensive care unit settings. METHODS: Prospective, observational, single-center study with 150 patients with ARDS defined by Berlin definition, receiving IMV with lung protective strategy...

It is well-established that arterial pH decreases with increased temperature in amphibians and reptiles through an elevation of arterial PCO2, but the underlying regulation remains controversial. The alphastat-hypothesis ascribes the pH fall to a ventilatory regulation of protein ionization, but the pH reduction with temperature is lower than predicted by the pK change of the imidazole-group on histidine. We hypothesize that arterial pH decreases at high, but not at low, temperatures when toads (Rhinella marina) and snakes (Python molurus) are exposed to hyperoxia...

Mechanical ventilation has, since its introduction into clinical practice, undergone a major evolution from controlled ventilation to diverse modes of assisted ventilation. Conventional mechanical ventilators depend on flow sensors and pneumatic pressure and controllers to complete the respiratory cycle. Neurally adjusted ventilatory assist (NAVA) is a new form of assisted ventilation in recent years, which monitors the electrical activity of the diaphragm (EAdi) to provide an appropriately level of pressure support...

Mechanical ventilation serves as crucial life support for critically ill patients. Although it is life-saving prolonged ventilation carries risks and complications like barotrauma, Ventilator-associated pneumonia, sepsis, and many others. Optimizing patient-ventilator interactions and facilitating early weaning is necessary for improved intensive care unit (ICU) outcomes. Traditionally Pressure support ventilation (PSV) mode is widely used for weaning patients who are intubated and mechanically ventilated. Neurally adjusted ventilatory assist (NAVA) mode of the ventilator is an emerging ventilator mode that delivers pressure depending on the patient's respiratory drive, which in turn prevents over-inflation and improves the patient's ventilator interactions...

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BACKGROUND: Mortality rates in patients with COVID-19 undergoing mechanical ventilation in the intensive care unit are high. The causes of this mortality have been rigorously investigated. The aim of the present study is to establish mortality risk factors related to lung mechanics measured at days 1 and 5 in patients with covid-19 ARDS managed with invasive mechanical ventilation in the intensive care unit. METHODS: A retrospective observational multicenter study including consecutive patients with a confirmed diagnosis of COVID-19-induced ARDS, admitted to three institutions and seven intensive care units in the city of Bogota between May 20, 2020 and May 30, 2022 who required mechanical ventilation for at least five days...

OBJECTIVE: To describe lung mechanics in Pediatric Acute Respiratory Distress Syndrome (PARDS) associated with acute COVID-19 and MIS-C with respiratory failure. METHODS: A concurrent multicenter observational study was performed, analyzing clinical variables and pulmonary mechanics of PARDS associated with COVID-19 in 4 Pediatric intensive care units (PICU) in Peru. The subgroup analysis included PARDS associated with multisystem inflammatory syndrome in children (MIS-C), MIS-PARDS, and PARDS with COVID-19 primary respiratory infection, C-PARDS...

RATIONALE: The physiological factors modulating the severity of snoring have not been adequately described. Airway collapse or obstruction is generally the leading determinant of snore sound generation; however, we suspect that ventilatory drive is of equal importance. OBJECTIVE: To determine the relationship between airway obstruction and ventilatory drive on snore loudness. METHODS: In 40 patients with suspected or diagnosed OSA (1-98 events/hour), airflow was recorded via pneumotach attached to an oronasal mask, ventilatory drive using calibrated intraesophageal diaphragm electromyography, and snore loudness using a calibrated microphone attached over the trachea...

Diaphragm inactivity during invasive mechanical ventilation leads to diaphragm atrophy and weakness, hemodynamic instability, and ventilatory heterogeneity. Absent respiratory drive and effort can, therefore, worsen injury to both lung and diaphragm and is a major cause of failure to wean. Phrenic nerve stimulation (PNS) can maintain controlled levels of diaphragm activity independent of intrinsic drive and as such may offer a promising approach to achieving lung and diaphragm protective ventilatory targets...

OBJECTIVES: The long-term cardiopulmonary outcomes following preterm birth during the surfactant era remain unclear. Respiratory symptoms, particularly exertional symptoms, are common in preterm children. Therefore, cardiopulmonary exercise testing may provide insights into the pathophysiology driving exertional respiratory symptoms in those born preterm. This review aims to outline the current knowledge of cardiopulmonary exercise testing in the assessment of children born preterm in the surfactant era...

PURPOSE: To describe the clinical course of ARDS during the first three days of mechanical ventilation, to compare ventilatory setting, respiratory mechanics and gas exchange variables collected during the first three days of mechanical ventilation between patients who survived and died during intensive care unit (ICU) stay and to investigate the variables associated with mortality at ICU admission and throughout the first three days of mechanical ventilation. MATERIALS AND METHODS: Prospective observational study...

BACKGROUND: Studies investigating the effect of trunk inclination on respiratory mechanics in mechanically ventilated ARDS patients have reported postural differences in partition respiratory mechanics. Compared with more upright positions, the supine-flat position provided lower lung and chest wall elastance, allowing reduced driving pressures and end-inspiratory transpulmonary pressure. However, the effect of trunk inclination on respiratory mechanics in obese patients with ARDS is uncertain...

Repeated obstruction and closure of the upper airway, sporadic hypoxic episodes, and sympathetic activity are symptoms of obstructive sleep apnea (OSA). Obstructive sleep apnoea is due to a combination of altered upper airway structure and muscular function, a low arousal threshold and increased loop gain. Although recurrent upper airway (UA) collapse during sleep is the most frequent clinical hallmark of OSA, the exact cause of this collapse is unknown. Furthermore, while continuous positive airway pressure aids in the management of OSA, many patients find it intolerable...

The central leptin signaling system has been found to facilitate breathing and is linked to obesity-related hypoventilation. Activation of leptin signaling in the nucleus tractus solitarii (NTS) and retrotrapezoid nucleus (RTN) enhances respiratory drive. In this study, we investigated how medullary leptin signaling contributes to hypoventilation and whether respective deletion of SOCS3 in the NTS and RTN could mitigate hypoventilation in diet-induced obesity (DIO) male mice. Our findings revealed a decrease in the number of CO2 -activated NTS neurons and downregulation of acid-sensing ion channels in DIO mice compared to lean control mice...

BACKGROUND: The carbonic anhydrase inhibitor sulthiame reduces OSA severity, increases overnight oxygenation, and improves sleep quality. Insights into how sulthiame modulates OSA pathophysiologic features (endotypic traits) adds to our understanding of the breathing disorder itself, as well as the effects of carbonic anhydrases in respiratory regulation. RESEARCH QUESTION: How does sulthiame treatment modify endotypic traits in OSA? STUDY DESIGN AND METHODS: Per-protocol tertiary analysis of a randomized controlled trial with the inclusion criteria as follow: BMI, ≥ 20 to ≤ 35 kg/m2 ; age, 18-75 years; apnea-hypopnea index (AHI) ≥ 15 events/h; Epworth sleepiness scale score, ≥ 6; as well as nonacceptance or nontolerance of positive airway pressure treatment...

BACKGROUND: Trunk inclination from semirecumbent head-upright to supine-flat positioning reduces driving pressure and increases respiratory system compliance in patients with acute respiratory distress syndrome (ARDS). These effects are associated with an improved ventilatory ratio and reduction in the partial pressure of carbon dioxide (PaCO2 ). However, these physiological effects have not been completely studied, and their mechanisms have not yet been elucidated. Therefore, this study aimed to evaluate the effects of a change in trunk inclination from semirecumbent (45°) to supine-flat (10°) on physiological dead space and ventilation distribution in different lung regions...

We have examined the importance of three long-standing questions concerning chemoreceptor influences on cardiorespiratory function which are currently experiencing a resurgence of study among physiologists and clinical investigators. Firstly, while carotid chemoreceptors (CB) are required for hypoxic stimulation of breathing, use of an isolated, extracorporeally perfused CB preparation in unanaesthetized animals with maintained tonic input from the CB, reveals that extra-CB hypoxaemia also provides dose-dependent ventilatory stimulation sufficient to account for 40-50% of the total ventilatory response to steady-state hypoxaemia...