Very limited air elimination capability of the level 1 fluid warmer

To determine the volume of air in 1000-ml crystalloid bags before and after connection to an infusion set; and to determine the volume of air that is not eliminated by the air eliminator in the Level 1 fluid warming device (Level 1 Technologies, Inc., Rockland, MA) when air boluses of different volumes enter into the fluid warming set.

Prospective analysis and laboratory investigation.

Operating room (OR) and research laboratory of a university hospital.

Air was aspirated from 200 collapsible, 1000-ml crystalloid bags: 100 before being connected to an infusion set and 100 after being connected to a patient in the OR. A roller pump from a cardiopulmonary bypass machine was connected to a Level 1 D-300 fluid administration set to maintain a continuous flow of normal saline through its air eliminator at a flow that approximated gravity or two thirds maximal flow, which is the rate achieved when fluid is pressurized to 300 mmHg throughout the system. Different volumes of air were administered and the air that passed through the air eliminator was measured.

Nonspiked bags contained 56.2 +/- 4 ml (mean +/- SD) of air (range 43-66 ml), and spiked bags contained 61.2 +/- 13 ml of air (range 4-102 ml), a significant difference (p < 0.0001). The amount of air passing through the air eliminator differed significantly at gravity and at two thirds maximal flow with boluses of 5, 10, 20, and 30 ml of air (p < 0.0001), but not with the 60 ml bolus of air. The amount of air passing through the eliminator also differed significantly (p < 0.0001) between boluses of different sizes at each flow rate. At the higher flow rate, even small boluses of air were not reliably eliminated; up to 56% of a 5 ml air bolus passed through the eliminator.

Air must be rigorously eliminated from all fluid containers because of the limited air elimination capability of the Level 1 air eliminator.