Fig. 30.1
Postoperative use of NIV in obese patients. (a) Prophylactic use of CPAP in an obese patient after laparoscopic sleeve gastrectomy through a CPAP mask with integral Venturi flow driver and adjustable PEEP valve (Ventumask; StarMed; Mirandola, Italy). (b) Therapeutic use of NPPV (PSV + PEEP) in an obese patient with respiratory failure after gastric bypass surgery delivered by a helmet for NIV (CaStar R; StarMed; Mirandola, Italy). Written informed consent was obtained from patients
30.2.6.2 Postoperative Curative Use of NIV in Obese Patients
No data are available in the literature regarding the role of NIV for postoperative treatment of ARF in obese patients.
In a study of 72 nonobese patients with ARF after abdominal surgery who were treated with NPPV (PSV + PEEP; Servo-Ventilator 300; Siemens; Elema, Sweden; or Evita 4; Dräger Medical; Lübeck, Germany) via face mask, Jaber et al. [14] found that 67 % of patients avoided intubation [14]. Within the first NPPV observation period, a significant benefit was observed only in the NPPV group, with increased PaO2/FiO2 (+36 ± 29), decreased respiratory rate (from 28.2 ± 3.4 to 23.1 ± 3.8 breaths/min), reduced length of ICU stay, and reduced mortality rate [14].
One meta-analysis showed that NIV reduced reintubation rates (odds ratio (OR) 0.24), incidence of pneumonia (OR 0.27), and ICU length of stay (0.44 days) when applied after major surgery [15]. There was insufficient evidence to suggest that NIV improves ICU survival, but an increased hospital survival was observed when NIV was used after surgery (OR 4.54) [15].
30.3 Conclusion
Obese patients present preoperative changes in respiratory function. Anesthesia and surgery can profoundly impair respiratory function, increasing the risk of postoperative respiratory complications and ARF. Evidence supports early administration of NIV as a prophylactic and as a therapeutic tool after surgery in obese patients for improving respiratory function and gas exchange. Selection of the correct interface (face or nasal mask vs helmet) and the type of NIV (CPAP vs NPPV) together with proper monitoring of the patient during NIV is fundamental for increasing the likelihood of success of NIV.
Key Major Recommendations
Obese patients have a restrictive pattern, which includes reduced lung volume and compromised respiratory system compliance. Obese patients may be hypoxemic with increased at-rest consumption of oxygen. Carbon dioxide is usually close to normal.
Anesthesia, surgery, and postoperative pain further reduce lung volumes, altering respiratory mechanics and gas exchange.
Early administration of NIV should be considered as a prophylactic and therapeutic tool in obese patients after surgery to improve respiratory function and gas exchange and to avoid respiratory failure.
CPAP essentially decreases upper airway obstruction and increases oxygenation by recruiting and stabilizing previously collapsed lung tissue, increasing lung volumes. NPPV unloads respiratory muscles, relieves dyspnea, and reduces the work required for breathing.
Conflict of Interest Disclosure
The authors have no interests to disclose.
References
1.
Adams JP, Murphy PG. Obesity in anaesthesia and intensive care. Br J Anaesth. 2000;85:91–108.PubMedCrossRef
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