Wednesday, July 12, 2006

Wednesday July 12, 2006

Case: 47 year old morbidly obese female with baseline history of COPD, successfully extubated post-op and admitted to ICU for overnight observation after gastric bypass surgery. Patient appears more lethargic in late evening and ABG was drawn which showed PH of 7.20, PO2 of 59 and PCO2 of 98 (pt's baseline PCO2 is around 55). You ordered nebulizer treatments and applied full face mask's noninvasive positive pressure ventilation (BiPAP) with setting of 10/5 (IPAP of 10 cm H2O and EPAP of 5 cm H20) and ordered ABG after one hour. Followup ABG is PH of 7.24, PO2 of 72 and PCO2 of 86. Patient is still lethargic.Your next step would be:

A) Increase IPAP with followup ABG in 1-2 hours

B) Change to nasal mask with followup ABG in 1-2 hours

C) Intubate patient

D) Continue present settings with followup ABGin 1-2 hours

Answer: C

Noninvasive positive pressure ventilation (BiPAP) should be use with caution in fresh gastric bypass patients and there should be a low threshold to intubate if situation arise. BiPAP pumps air into the small gastric pouch and can lead to complications like breakdown of suture lines, bowel perforation and gastric distension. Though one small study of 27 patients didn't show either any complication or advantage of BiPAP in the first 24 postoperative hours of severely obese patients with comorbid illnesses who have undergone elective gastric bypass 1 but there are case reports in literature showing potential complication and geniune concern for use of of bi-level positive airway pressure after gastric bypass surgery 2.

Reference: click to get abstract/article
The effect of bi-level positive airway pressure on postoperative pulmonary function following gastric surgery for obesity - Respiratory Medicine Volume 96, Issue 9, September 2002, Pages 672-676
A potential complication of bi-level positive airway pressure after gastric bypass surgery - Obes Surg. 2004 Feb;14(2):282-4.