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Background: Noninvasive ventilation with nose- or face-masks has been increasingly used in the past. The objective of mechanical ventilation is in addition to improve gas exchange to reduce breathing work. While improvement on breathing work has been shown mainly on normal-weight patients with different respiratory diseases, there is no existing data about the effect of noninvasive ventilation on the breathing work of patients with massive obesity., Patients and Methods: Assisted mask-ventilation with bilevel positive airway pressure (BiPAP) was carried out on 5 overweight control subjects (overweight controls), 7 overweight patients with obstructive sleep apnea (OSA), 6 patients with obesitas-hypoventilation syndrome (OHS), and 7 overweight patients with chronic obstructive lung disease (COLD). Inspiratory pressure assist (IPAP) was set to 12 or 16 cm H2O, exspiratory pressure (EPAP) was set to 5 cm H2O. All, subjects were massive overweight (body mass index [BMI] 42.2 +/- 5.8; range 31.8 to 55.4 kg/m2). Respiratory muscle activity was measured as esophageal pressure change (delta Pes) and transdiaphragmatic pressure change (delta Pdi) and calculated as pressure time integral., Results: With noninvasive ventilation respiratory muscle activity was significantly (p < 0.05) reduced in all groups at least 40% compared to baseline values during spontaneous respiration., Conclusions: Noninvasive ventilation via face masks can efficiently reduce work of breathing in subjects with massive obesity.

Background: The aim of the present study was to evaluate if Proportional Assist Ventilation (PAV), when applied noninvasively via face mask, can reduce ventilatory effort in patients with respiratory failure. We present preliminary results of an ongoing study., Patients and Methods: In 5 patients with respiratory failure due to different underlying disorders (pulmonary fibrosis, bilateral diaphragm paralysis, COPD) we compared the transdiaphragmal pressure-time integral. PTdi (integral off Pdi dt) after 15 minutes of noninvasive PAV to the baseline values without ventilatory support., Results and Conclusion: Four patients showed reduction of PTdi to various extend. One patient who presented low diaphragmal activity at baseline due to diaphragmal paralysis showed a slight increase in PTdi during ventilation. Mean PTdi decreased by 26.7%. PaCO2 in the 5 patients showed no significant change after 15 minutes of ventilation, thus indicating that with noninvasive PAV patients can maintain constant ventilation with reduced effort.