Effect of PEEP on the rate of thoracic duct lymph flow and clearance of bacteria from the peritoneal cavity

Abstract

A nonvirulent strain of E. coli, type K 12F-, that was labelled with chromium-51 was injected intraperitoneally. The thoracic duct was cannulated in the left side of the neck. Dogs were randomly divided into two groups. In Group A, six dogs were ventilated with a mechanical ventilator for 1 hour. They were then ventilated with PEEP (expiratory limb of the nonrebreathing system 10 cm below water level) for 1 hour, and finally ventilated without PEEP for another 30 minutes. In Group B, five dogs were initially ventilated with PEEP in the same manner employed in Group A for 1 hour, then were ventilated without PEEP for 1 hour, and finally were again ventilated with 10 cm PEEP for 30 minutes. Thoracic duct lymph was collected in 10 minute aliquots throughout the experiment. In Group A, when PEEP was instituted after a period of mechanical ventilation, there was significant diminution in the rate of lymph flow, but no significant change in bacterial clearance. When PEEP was discontinued, both lymph flow rate and bacterial clearance increased significantly. In Group B, when PEEP was removed, both lymph flow rate and bacterial clearance increased significantly. When PEEP was reinstituted, the rate of lymph flow significantly decreased, but the change in bacterial clearance was not significant. PEEP may exert a deleterious effect on the clearance of bacteria and particulate debris from the peritoneal cavity through the thoracic lymphatic vessels and should be used with caution in patients with abdominal sepsis.