Weisberger S A, Carlo W A, Chatburn R L, Fouke J M, Martin R J
J Pediatr. 1986 Apr;108(4):596-600. doi: 10.1016/s0022-3476(86)80846-0.
Although high-frequency jet ventilation may reduce barotrauma, the optimal ventilator settings at which complications are minimized have not been determined. To develop ventilator strategies applicable to the human infant, we studied six New Zealand rabbits before and after saline lung lavage. Changes in functional residual capacity (delta FRC) and airway pressure gradient (peak inspiratory pressure minus positive end-expiratory pressure) were measured while inspiratory time (TI) and expiratory time (TE) were varied. Frequencies of 120, 240, and 480 cycles per minute and inspiratory to expiratory ratios of 1:1, 1:3, 1:5, and 1:9 resulted in TI that varied from 12 to 250 msec, and TE from 62 to 450 msec. Analysis of variance demonstrated that as TI was shortened, a significantly higher airway pressure gradient was necessary to maintain a constant tidal volume. As TE was shortened, air trapping, as determined from both inadvertent positive end-expiratory pressure and delta FRC, significantly increased. Lung lavage increased the airway pressure gradient at each TI, but decreased air trapping at each TE. At no time did entrainment contribute to the delivered tidal volume. We conclude that a relatively narrow range of TI and TE may be necessary for optimal use of high-frequency jet ventilation to reduce airway pressures and minimize the risk of air trapping.
尽管高频喷射通气可能会减少气压伤，但尚未确定能将并发症降至最低的最佳通气机设置。为了制定适用于人类婴儿的通气策略，我们对六只新西兰兔在盐水肺灌洗前后进行了研究。在改变吸气时间（TI）和呼气时间（TE）的同时，测量功能残气量（ΔFRC）和气道压力梯度（吸气峰压减去呼气末正压）的变化。每分钟120、240和480次循环的频率以及1:1、1:3、1:5和1:9的吸呼比导致TI从12到250毫秒不等，TE从62到450毫秒不等。方差分析表明，随着TI缩短，维持恒定潮气量需要显著更高的气道压力梯度。随着TE缩短，根据不经意的呼气末正压和ΔFRC确定的气体潴留显著增加。肺灌洗增加了每个TI时的气道压力梯度，但减少了每个TE时的气体潴留。在任何时候，夹带都不会对输送的潮气量产生影响。我们得出结论，为了最佳地使用高频喷射通气以降低气道压力并将气体潴留风险降至最低，可能需要相对较窄范围的TI和TE。
