Efficiency of a gas diffuser and influence of suction in carbon dioxide deairing of a cardiothoracic wound cavity model.

OBJECTIVE

In cardiac surgery, insufflation of carbon dioxide is used for deairing of the heart and great vessels. The aim of this study was to assess a new insufflation device for efficient deairing and to study the influence of suction.

METHODS

We measured the content of remaining air at two positions in the cardiothoracic wound model. A new insufflation device, a gas diffuser, was compared with a conventional 0.25-inch tube. Carbon dioxide flow (5 and 10 L/min) and suction (0, 1.5, 10, and 25 L/min) were varied. Suction was studied in combination with the gas diffuser.

RESULTS

With the tube the median air content in the wound model was 19.5% to 51.7% at the studied carbon dioxide flows, whereas with the gas diffuser the median air content was no greater than 1.2% at 5 L/min and no greater than 0.31% at 10 L/min (P <.001). When suction of 1.5 L/min was applied, the median air content in the model remained low (<or =1.0%) at both carbon dioxide flows. With suction of 10 L/min the median air content was still low (<or =0.50%) at a simultaneous carbon dioxide flow of 10 L/min. Conversely, suction of 25 L/min caused a marked increase in air content at carbon dioxide flows of both 5 and 10 L/min (P <.001).

CONCLUSIONS

This study demonstrated that the most efficient deairing (<or =1% remaining air) in a cardiothoracic wound model was provided by a gas diffuser at a carbon dioxide flow of 10 L/min. A conventional 0.25-inch tube failed to do so (19.5%-51.7% remaining air). Additional suction deteriorated air displacement with the gas diffuser when suction exceeded carbon dioxide inflow.