Table 1.

Main studies assessing oxygen and NIV ventilation (prophylactic and curative) on studies focused in patients with obesity

Study first author, journal, year of publication	Design of the study	Inclusion criteria	Comparators (number of patients per group)	Main result	Other results
El-Solh AA. Eur Respir J 2006	Prospective study with historical matching	Extubation of patients with BMI ≥ 35 kg/m2 in ICU Prophylactic NIV	124 patients 62 consecutive patients were assigned to NIV via nasal mask immediately post-extubation 62 historically matched controls treated with conventional oxygen therapy	16% (95% confidence interval 2.9–29.3%) absolute risk reduction in the rate of respiratory failure in the first 48 h post-extubation	Post hoc analysis of the 47 patients who had hypercapnia during a trial of spontaneous breathing: reduced hospital mortality
Duarte AG. Critical Care Medicine 2007	Retrospective study	Patients with morbid obesity with ARF requiring ventilatory assistance Curative NIV	50 patients 33 patients treated with NIV, 17 with IMV	21 avoided intubation (NIV success) and 12 required intubation (NIV failure)	Significant improvements in pH and Paco2 were noted for the IMV and NIV success groups Hospital mortality for the IMV and NIV failure groups was increased
Neligan PJ. Anesthesiology 2009	Randomized controlled trial	Patients with morbid obesity and known obstructive sleep apnea undergoing laparoscopic bariatric surgery Prophylactic NIV	40 patients 20 in the continuous positive airway pressure via the Boussignac system immediately after extubation (Boussignac group) 20 in the supplemental oxygen (standard care group)	Less reduction in forced vital capacity from baseline to 24 h after extubation in the Boussignac group	Less reduction in forced expiratory volume in 1 s and peak expiratory flow rate in the Boussignac group
Zoremba M. BMC anesthesiology 2011	Prospective observational study	Patients with BMI 30–45 kg/m2 undergoing minor peripheral surgery Prophylactic NIV	60 patients 30 were randomly assigned to receive short-term NIV 30 received routine treatment (supplemental oxygen via Venturi mask)	During the PACU stay, inspiratory and expiratory lung function in the NIV group was significantly better than in the controls (p < 0.0001)	Blood gases and the alveolar to arterial oxygen partial pressure difference were also better in the NIV group
Lemyze M. Plos One 2014	Prospective observational study	Patients with BMI > 40 kg/m2 prospectively included diagnosed with OHS and treated by NIV for ARF Curative NIV	76 patients under NIV	NIV failed to reverse ARF in 13 patients	The patients failing NIV experienced poor outcome despite early resort to endotracheal intubation (in-hospital mortality, 92.3% vs 17.5%; p < 0.001)
Corley A. Intensive Care Med 2015	Randomized controlled trial	Patients with extubation post-cardiac surgery with a BMI ≥ 30 kg/m2 Prophylactic HFNC	155 patients 74 in the control group (conventional oxygen therapy) 81 in the HFNC group	No difference was seen between groups in atelectasis scores on Day 1 or 5	In the 24-h post-extubation, there was no difference in mean PaO2/FiO2 ratio or respiratory rate
Stephan F. Respir Care 2017	Post hoc analysis of a randomized controlled trial	Patients with obesity Extubation after cardiothoracic surgery Prophylactic and curative NIV	231 patients 136 in the NIV group, 135 in the HFNC group	Treatment failure (defined as re-intubation, switch to the other treatment, or premature discontinuation) did not significantly differ between groups	No significant differences were found for dyspnea and comfort scores. Skin breakdown was significantly more common with NIV after 24 h

NIV noninvasive ventilation, ARF acute respiratory failure, BMI body mass index, HFNC high-flow nasal cannula oxygen, OHS obesity hypoventilation syndrome, IMV invasive mechanical ventilation