The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts


Susan Lagambina1, Paul F. Nuccio1, Maria Digiorgio1, Gerald L. Weinhouse2

Introduction: Ventilating patients with air leaks can be challenging. Most approaches focus on maintaining a normal acid-base balance with a protective lung strategy. We present a patient who had a right pleurectomy; developed a right sided pneumothorax, subcutaneous air and a pneumomediastinum. Initial ABG showed a slight respiratory acidosis. 60 minutes post-op the patient had a worsening air leak, and became severely alkalotic. The ventilator began continuously alarming patient disconnect. We developed a plan to reverse alkalosis while maintaining line suction and mechanical ventilation without continuous alarming.

Case Summary: A 67-year-old male with right malignant pleural mesothelioma, in the ICU, mechanically ventilated, had 3 chest tubes on suction at -20 cmH20. He had no spontaneous respirations due to sedation. A CXR on suction showed improvement in the pneumothorax and subcutaneous air. ABG showed a respiratory alkalosis with pH 7.57 and PaCO2 25. On line suction the patient's ventilator began continuously alarming patient disconnect. Changed his ventilator settings to improve alkalosis but the vent alarms didn't resolve. The chest tubes were put on water seal, the leak decreased, VT's increased to 380mL and the ventilator stopped alarming. A follow-up CXR showed increased subcutaneous air and worsening pneumothorax. Lowered suction to -10 cmH20, the ventilator continued alarming patient disconnect. Sedation was reduced to allow for spontaneously breathing while maintaining pain control. With a 400cc+ chest tube leak, he was placed on CPAP 10 while the chest tubes were on water seal and VT's were about 450mL with a RR of 12. The chest tubes were put back to -20 cmH20, the vent began alarming patient disconnect. A low-flow nebulizer was added at 2lpm from external flow to augment the exhaled volumes on the PB840. The ventilator stopped alarming and follow up ABG was normal. The CXR was improved. The patient maintained normal ABG for the next 48 hours with a resolved pneumomediastinum, pneumothorax and minimal subcutaneous emphysema.

Discussion: Numerous cases have been reported that the gas exiting a chest tube has participated in gas exchange. Therapists should remember despite a mechanical ventilator registering extremely low exhaled VT's that the patient's overall assessment needs to be taken into account before increasing settings to improve the ventilator.

Bishop, et al (Chest 1987;91:400-02)
Gribetz. (Crit Care Med 1987;92;577)