Liggins Institute, University of Auckland, Auckland, New Zealand.
Neonatology. 2009;96(4):259-64. doi: 10.1159/000220765. Epub 2009 May 27.
Despite increasing survival in the smallest preterm infants, the incidence of chronic lung disease has not decreased. Research into ventilatory strategies has concentrated on minimising barotrauma, volutrauma and atelectotrauma, but little attention has been paid to the role of bias gas flow rates and the potential for rheotrauma or shear stress injury. Ventilated preterm infants frequently receive relatively high gas flow rates.
We hypothesised that altering bias gas flow rates would change the efficiency of ventilation and thereby affect ventilatory parameters.
We tested this hypothesis using an artificial lung followed by ventilation of 8 term lambs.
Between flows of 2 and 15 l/min, inflation time (Ti) in the artificial lung was inversely related to the bias gas flow rate. In the ventilated lambs, Ti was inversely related to flow rates up to 10 l/min, with no statistically significant effect at flow rates >10 l/min. There were no adverse effects on gas exchange or cardiovascular parameters until a flow rate of 3 l/min was used, when inadequate gas exchange occurred.
Ti is inversely associated with the bias gas flow rate. Flow rates much lower than those used in many neonatal units seem to provide adequate ventilation. We suggest that the role of ventilator gas flow rates, which may potentially influence shear stress in ventilator-induced lung injury, merits further investigation.
尽管最小早产儿的存活率有所提高，但慢性肺病的发病率并未降低。通气策略的研究集中在尽量减少气压伤、容量伤和肺不张伤，但对偏置气流速率的作用以及潜在的流变伤或剪切力损伤关注较少。接受通气的早产儿通常接受相对较高的气流速率。
我们假设改变偏置气流速率会改变通气效率，从而影响通气参数。
我们使用人工肺对 8 只足月羔羊进行通气，对这一假设进行了测试。
在 2 至 15 l/min 的流量之间，人工肺中的充气时间（Ti）与偏置气体流量呈反比。在通气羔羊中，Ti 与流量呈反比，直至达到 10 l/min，超过 10 l/min 时无统计学意义。在使用 3 l/min 的流量之前，气体交换或心血管参数没有不良反应，当发生气体交换不足时，使用 3 l/min 的流量。
Ti 与偏置气体流量呈反比。比许多新生儿病房中使用的气流速率低得多的气流速率似乎可以提供足够的通气。我们建议，进一步研究可能影响呼吸机诱导性肺损伤剪切力的呼吸机气体流量的作用是值得的。
