Respiratory Management of Perioperative Obese Patients

Abstract

SummaryWith a rising incidence of obesity in the United States, anesthesiologists are faced with a larger volume of obese patients coming to the operating room as well as obese patients with ever-larger body mass indices (BMIs). While there are many cardiovascular and endocrine issues that clinicians must take into account when caring for the obese patient, one of the most prominent concerns of the anesthesiologist in the perioperative setting should be the status of the lung. Because the pathophysiology of reduced lung volumes in the obese patient differs from that of the ARDS patient, the best approach to keeping the obese patient's lung open and adequately ventilated during mechanical ventilation is unique. Although strong evidence and research are lacking regarding how to best ventilate the obese surgical patient, we aim with this review to provide an assessment of the small amount of research that has been conducted and the pathophysiology we believe influences the apparent results. We will provide a basic overview of the anatomy and pathophysiology of the obese respiratory system and review studies concerning pre-, intra-, and postoperative respiratory care. Our focus in this review centers on the best approach to keeping the lung recruited through the prevention of compression atelectasis and the maintaining of physiological lung volumes. We recommend the use of PEEP via noninvasive ventilation (NIV) before induction and endotracheal intubation, the use of both PEEP and periodic recruitment maneuvers during mechanical ventilation, and the use of PEEP via NIV after extubation. It is our hope that by studying the underlying mechanisms that make ventilating obese patients so difficult, future research can be better tailored to address this increasingly important challenge to the field of anesthesia.

High-Flow Nasal Cannula Therapy Versus Intermittent Noninvasive Ventilation in Obese Subjects After Cardiothoracic Surgery

“…25 A recent metaanalysis confirmed that the use of NIV after cardiothoracic surgery improved subjects's oxygenation and decreased the need for endotracheal intubation. 26 NIV is one of the recommended treatments to improve pulmonary function and gas exchange in obese patients [5][6][7][8][9]11,27 and has been studied extensively in the postoperative period of abdominal surgery. 28,29 Interestingly, NIV can unload the inspiratory muscles of obese patients 27 and was superior to continuous positive airway pressure regarding the improvement of atelectasis 30 after cardiac surgery.…”

“…2 Hence, obesity is a risk factor for postoperative hypoxemia after cardiac 3 or thoracic 4 surgery. Prophylactic use of noninvasive ventilation (NIV) is recommended in this specific population in the postoperative period [5][6][7][8] or after extubation. 9 However, the success rate of NIV to treat acute respiratory failure in obese patients is currently unknown.…”

Characteristics of pneumonia with negative chest radiography in cases confirmed by computed tomography

“…As for body composition, a study by Upchurch et al reported obesity as significantly more common in patients with CT-only pneumonia than in those with pneumonia also appearing on chest radiography [12]. Obese patients are well known to frequently experience atelectasis, mainly in the lung bases [13]. CT-only pneumonia appeared more common among obese patients, perhaps due to lower attenuation from adipose tissue in obese patients.…”

Prevalence of sleep disorders in obese before bariatric surgery.

“…The authors suggest that NIV should be routinely used before the intubation procedure, aiming to increase the lumen in the airway, increasing permeability and facilitating the procedure of passage of the orotracheal tube (28) . And also as a strategy during weaning of mechanical ventilation, providing improvement of ventilatory mechanics and increasing the success of extubation without intercurrences (28,30) .…”

“…And also as a strategy during weaning of mechanical ventilation, providing improvement of ventilatory mechanics and increasing the success of extubation without intercurrences (28,30) . Prescription and titration of the pressure used must be individualized, requiring adequate medical and physiotherapeutic evaluation.…”