Henderson-Smart D J, Bhuta T, Cools F, Offringa M
NSW Centre for Perinatal Health Services Research, Queen Elizabeth II Institute for Mothers and Infants, Building DO2, University of Sydney, Sydney, NSW, Australia, 2006.
Cochrane Database Syst Rev. 2003(4):CD000104. doi: 10.1002/14651858.CD000104.
Respiratory failure due to lung immaturity is a major cause of mortality in preterm infants. Although intermittent positive pressure ventilation (IPPV) saves lives, lung distortion during its use is associated with lung injury and chronic lung disease (CLD). Conventional IPPV is provided at 30-80 breaths per minute while a newer form of ventilation called high frequency oscillatory ventilation (HFOV) provides 'breaths' at 10-15 cycles per second. This has been shown to result in less lung injury in experimental studies.
The objective of this review is to determine whether the elective use of high frequency oscillatory ventilation as compared to conventional ventilation (CV) in preterm infants who are mechanically ventilated for the respiratory distress syndrome decreases the incidence of chronic lung disease, without adverse effects.
Searches were made of the Oxford Database of Perinatal Trials, MEDLINE, EMBASE, previous reviews including cross references, abstracts, conferences and symposia proceedings, expert informants, journal hand searching by the Cochrane Collaboration, mainly in the English language. The search was updated in May 2003.
Randomized controlled trials comparing HFOV and CV in preterm or low birth weight infants with pulmonary dysfunction, mainly due to RDS, who are to be given IPPV. Randomization and commencement of treatment should have been as soon as possible after the start of IPPV and usually in the first 12 hours of life.
The methodological quality of each trial was independently reviewed by the various authors. Each author extracted data separately; they were compared and differences were resolved. Treatment effects were expressed using relative risk (RR) and risk difference (RD). From 1/RD the number needed to treat (NNT) to produce one outcome were calculated. Ninety five percent confidence intervals were used for all measures of effect.
Eleven eligible studies on 3,275 infants were included. Meta-analysis comparing HFOV with CV revealed no evidence of effect on mortality at 28-30 days of age or at approximately term equivalent age. These results were consistent across studies. The effect of HFOV on CLD in survivors at term equivalent GA was inconsistent across studies and not significant overall. Pre-specified subgroup analyses according to use of a high volume strategy, or use of surfactant, did not identify subgroups in which there was evidence of effect on death, or in which the size of effect on CLD was substantially increased, or in which heterogeneity of treatment effect on CLD was removed. Short term neurological morbidity caused by HFOV was found in some studies, but this effect was not statistically significant overall. The subgroup of two trials not using a high volume strategy with HFOV found increased rates of Grade 3 or 4 IVH and of periventricular leukomalacia. An adverse effect of HFOV on longer term neurodevelopment was found in one large trial but not in two other small trials which reported this outcome.
REVIEWER'S CONCLUSIONS: There is no clear evidence from this systematic review that elective HFOV, as compared with CV, offers important advantages when used as the initial ventilation strategy to treat preterm babies with acute pulmonary dysfunction. There is no evidence of a reduction in death rate. There may be a small reduction in the rate of CLD with HFOV use but the evidence is weakened by the inconsistency of this effect across trials and is not significant overall. Adverse effects on short term neurological outcomes have been observed in some studies but these effects are not significant overall. Information about effects on long term outcome is not adequate overall. Any future trials on elective HFOV should target those infants who are at most risk of CLD (extremely preterm), compare different strategies for generating HFOV and CV, and report important long term pulmonary and neurodevelopmental outcomes. Economic analysis should also be incorporated.
肺发育不成熟导致的呼吸衰竭是早产儿死亡的主要原因。尽管间歇正压通气（IPPV）挽救了许多生命，但使用过程中的肺变形与肺损伤及慢性肺病（CLD）相关。传统IPPV的频率为每分钟30 - 80次呼吸，而一种名为高频振荡通气（HFOV）的新型通气方式每秒提供10 - 15次“呼吸”。实验研究表明，HFOV可减少肺损伤。
本综述的目的是确定在因呼吸窘迫综合征接受机械通气的早产儿中，与传统通气（CV）相比，选择性使用高频振荡通气是否能降低慢性肺病的发生率且无不良影响。
检索了牛津围产期试验数据库、MEDLINE、EMBASE，以及之前的综述（包括交叉参考文献、摘要、会议和研讨会记录）、专家信息提供者，Cochrane协作网进行的期刊手工检索，主要检索语言为英语。检索于2003年5月更新。
比较HFOV和CV在主要因呼吸窘迫综合征导致肺功能障碍的早产儿或低体重儿中的随机对照试验，这些患儿需接受IPPV。随机分组和治疗应在IPPV开始后尽快进行，通常在出生后的前12小时内。
各作者独立评估每个试验的方法学质量。每位作者分别提取数据；对数据进行比较并解决差异。治疗效果用相对危险度（RR）和危险度差值（RD）表示。根据1/RD计算产生一个结果所需的治疗人数（NNT）。所有效应量均采用95%置信区间。
纳入了11项针对3275名婴儿的符合条件的研究。比较HFOV和CV的荟萃分析显示，在28 - 30日龄或接近足月等效年龄时，未发现对死亡率有影响的证据。这些结果在各研究中一致。HFOV对足月等效胎龄存活者慢性肺病的影响在各研究中不一致，总体上不显著。根据高容量策略的使用或表面活性剂的使用进行的预先指定亚组分析，未发现对死亡有影响证据的亚组，也未发现对慢性肺病影响大小显著增加或消除慢性肺病治疗效果异质性的亚组。一些研究发现HFOV会导致短期神经功能障碍，但总体上这种影响无统计学意义。两项未采用HFOV高容量策略的试验亚组中，3级或4级脑室内出血及脑室周围白质软化的发生率增加。一项大型试验发现HFOV对长期神经发育有不良影响，但另外两项报告此结果的小型试验未发现。
本系统综述没有明确证据表明，与CV相比，选择性使用HFOV作为治疗急性肺功能障碍早产儿的初始通气策略具有重要优势。没有证据表明死亡率降低。使用HFOV可能会使慢性肺病发生率略有降低，但各试验结果不一致削弱了该证据，总体上不显著。一些研究观察到对短期神经功能结局有不良影响，但总体上这些影响不显著。关于对长期结局影响的信息总体上不充分。未来任何关于选择性HFOV的试验都应针对慢性肺病风险最高的婴儿（极早产儿），比较产生HFOV和CV的不同策略，并报告重要的长期肺部和神经发育结局。还应纳入经济分析。
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