Slutsky A S, Menon A S
J Appl Physiol (1985). 1987 Feb;62(2):513-9. doi: 10.1152/jappl.1987.62.2.513.
We studied the effect of catheter position and flow rate on gas exchange during constant-flow ventilation (CFV) in eight anesthetized, paralyzed dogs. The distal tips of the insufflation catheters were positioned 0.5, 2.0, 3.5, and 5.0 cm from the tracheal carina. Flow rates were varied between 10 and 55 l/min and steady-state arterial blood gases were measured. At a given flow rate, arterial CO2 pressure (PaCO2) decreased as CFV was administered further into the lung up to a distance of 3.5 cm from the carina; there were no significant differences in PaCO2 at 3.5 and 5.0 cm. For a given catheter position, PaCO2 decreased with increasing flow rate up to a flow rate of 40 l/min. Further increases in flow rate had no significant effect on PaCO2. Arterial O2 pressure (PaO2) was relatively constant at all flow rates and catheter positions. We conclude that, up to a point, CO2 elimination can be improved by positioning the catheters further into the lung; advancing the catheters further than 3.5 cm from the carina may cause over-ventilation of specific lung regions resulting in a relative plateau in CO2 elimination and relatively constant PaO2's. Positioning the catheters further into the lung permits the use of lower flow rates, thus potentially minimizing the risk of barotrauma.
我们研究了在八只麻醉、麻痹的犬只进行恒流通气（CFV）期间，导管位置和流速对气体交换的影响。吹入导管的远端尖端距离气管隆突0.5、2.0、3.5和5.0厘米。流速在10至55升/分钟之间变化，并测量稳态动脉血气。在给定流速下，随着CFV在距隆突3.5厘米的范围内进一步深入肺部，动脉二氧化碳分压（PaCO2）降低；在3.5和5.0厘米处，PaCO2无显著差异。对于给定的导管位置，PaCO2随着流速增加至40升/分钟而降低。流速进一步增加对PaCO2无显著影响。在所有流速和导管位置，动脉氧分压（PaO2）相对恒定。我们得出结论，在一定程度上，将导管进一步置于肺部可改善二氧化碳清除；将导管从隆突推进超过3.5厘米可能导致特定肺区域过度通气，从而导致二氧化碳清除相对平稳且PaO2相对恒定。将导管进一步置于肺部可使用较低流速，从而潜在地将气压伤风险降至最低。
