Pathophysiology and Management of Acute Respiratory Distress Syndrome in Obese Patients

Abstract

A rising prevalence of obesity is reported over time and throughout the world. At the same time, the acute respiratory distress syndrome (ARDS) remains an important public health problem, accounting for approximately 10% of intensive care unit admissions and leading to significant hospital mortality. Even in the absence of acute illnesses, obesity affects respiratory mechanics and gas exchange in the setting of a restrictive disease. In the presence of ARDS, obesity adds various challenges to a safe and effective management of respiratory support. Difficult airway management, altered lung and chest wall physiology, and positional gas trapping are routinely encountered. The management of such difficult cases is generally empiric, as it is based on small-sized, physiologic studies or on suggestions from the general anesthesia literature. The present review focuses on those cases in which ARDS is coincident with obesity, with the aim of presenting treatment options based on the current evidence. The first part summarizes the epidemiology of obesity and ARDS. Then the diagnostic challenges due to obesity-related artifacts of the different imaging techniques will be presented. A subsequent, detailed description of the altered respiratory anatomy and physiology of obesity will provide help in selecting an optimal, individually tailored strategy of support. Furthermore, we will discuss how esophageal manometry should be used to adjust the settings of positive end-expiratory pressure and tidal volume; the challenges of prone positioning and extracorporeal support; and the optimal strategies for weaning from mechanical ventilation, including when and how to perform a tracheostomy.

High Respiratory Drive and Excessive Respiratory Efforts Predict Relapse of Respiratory Failure in Critically Ill Patients with COVID-19

“…The main endpoint of the study was a relapse of respiratory failure during the weaning process of invasive mechanical ventilation in the 24-hour period following measurements defined by the presence of at least one of the following criteria: decrease of Pa O 2 /F i O 2 ratio ≥20%, or severe hypoxemia (oxygen saturation as measured by pulse oximetry [Sp O 2 ] <88% under F i O 2 ≥60% for >15 min), new onset of respiratory acidosis (pH <7.35), or increase of Pa CO 2 ≥10 mm Hg in patients with preceding respiratory acidosis. Ventilator settings were optimized in case of respiratory worsening as follows: 2 cm H 2 O stepwise increase of pressure support (PS) until 14 cm H 2 O when respiratory rate was >35/min or V t was <6 ml/kg of predicted body weight (PBW), decrease of PS until 0 cm H 2 O or increase of sedation (without loss of spontaneous breathing) in case of V t >8 ml/kg of PBW, and 2 cm H 2 O stepwise increase of PEEP until 16 cm H 2 O when Sp O 2 /F i O 2 was <150 ( 10 ). If temporary deoxygenations were observed (e.g., following an accidental ventilator disconnection, airway suctioning, transport to computed tomographic scan) and were not followed by any medical intervention (i.e., change of ventilator settings, increase in sedations), they were not considered a relapse of respiratory failure.…”

COVID-19 and obesity in childhood and adolescence: a clinical review

“…In fact, hematosis is impaired in obesity, which becomes even more relevant when the exchange areas are reduced due to coronavirus action. 65 The pressure exerted by abdominal adiposity on the lungs, through the diaphragm, also acts to limit the movement of respiratory muscles, with less oxygen saturation 66 and worsening clinical presentation due to the lower lung volume of obese patients. 67 In addition, some comorbidities linked to obesity may contribute to a higher risk of pulmonary infections, such as the presence of asthma, which is highly prevalent among obese children, 68 and obstructive sleep apnea.…”

The Association Between the Mechanical Ventilator Pressures and Outcomes in a Cohort of Patients with Acute Respiratory Failure

“…These effects depend on the degree of obesity and the distribution of fatty tissue. 2,9 Obese patients in the supine position often have cephalad movement of the diaphragm and have reduced lung volumes. In addition, they have increased intrapleural pressures and atelectasis in dependent lung zones of the lung.…”

“…In addition, obesity has potential effects on both the lung parenchyma and the chest wall. 2 Monitoring intrathoracic pressures provides an overall parameter, which is affected by ongoing acute and chronic medical problems in any particular patient. In addition, pressures, such as a plateau pressure and the driving pressure, warrant attention because elevations in these pressures indicate the need for patient reassessment and possibly adjustments in the ventilation.…”