Non-invasive ventilation corrects alveolar hypoventilation during spinal anesthesia.

PURPOSE To document and explain the beneficial effects of non-invasive ventilation in correcting hypoxemia and hypoventilation in severe chronic obstructive pulmonary disease, during spinal anesthesia in the lithotomy position. CLINICAL FEATURES A morbidly obese patient with severe chronic obstructive pulmonary disease underwent prostate surgery in the lithotomy position under spinal anesthesia. Hypoxemia was encountered during surgery, and a profound decrease of forced vital capacity associated with alveolar hypoventilation and ventilation/perfusion mismatching were observed. In the operating room, an M-mode sonographic study of the right diaphragm was performed, which confirmed that after spinal anesthesia and assuming the lithotomy position, there was a large decrease (-30%) in diaphragmatic excursion. Hypoxemia and alveolar hypoventilation were successfully treated with non-invasive positive pressure ventilation. CONCLUSIONS Intraoperative application of non-invasive positive pressure ventilation improved diaphragmatic excursion and overall respiratory function, and reduced clinical discomfort in this patient.