Aim

In permissive hypercapnia high levels of carbon dioxide (CO₂) are tolerated in ventilated preterm infants to minimise lung injury, but hypercapnia could directly impair oxygenation. We aimed to quantify the association of elevated CO₂ with oxygenation impairment in preterm infants by measuring the right-to-left shunt and the ventilation/perfusion (V_A/Q) ratio.

Methods

Pre-existing datasets from preterm infants during the acute phase of respiratory distress syndrome or with evolving or established bronchopulmonary dysplasia were analysed. Non-invasive paired measurements of the fraction of inspired oxygen (F_IO₂) and transcutaneous oxygen saturation (SpO₂) were used to calculate the degree of right-to-left shunt, right shift of the F_IO₂ versus SpO₂ curve and the V_A/Q.

Results

A total of 75 infants (43 male) with a median (IQR) gestational age of 26.4 (24.7–27.7) weeks were studied at 7 (2–31) days. Thirty-six infants (48 %) had an arterial partial pressure of CO₂ (PaCO₂) above 6 kPa. The PaCO₂ was independently associated with the right shift of the curve [adjusted p < 0.001, unstandardised coefficient; 2.26, 95 % CI: 1.51–2.95] and the right-to-left shunt [adjusted p = 0.016, unstandardised coefficient; 1.86, 95 % CI: 0.36–3.36] after adjusting for confounders. An increase of the PaCO₂ from 5 to 8 kPa, corresponded to a right shift of the curve of 20.2 kPa or a decrease in the V_A/Q from 0.66 to 0.24.

Conclusions

Increased carbon dioxide levels were significantly associated with impaired oxygenation in preterm infants with respiratory distress syndrome or bronchopulmonary dysplasia.

中文翻译：

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早产儿通气的允许性高碳酸血症和氧合损伤

目的

在允许性高碳酸血症中，通气早产儿可以耐受高水平的二氧化碳 (CO _{2 )，以尽量减少肺损伤，但高碳酸血症可能会直接损害氧合。}我们的目的是通过测量右向左分流和通气/灌注 (V _A /Q) 比率来量化早产儿中 CO ₂升高与氧合损伤的关联。

方法

对呼吸窘迫综合征急性期或正在发展或已确定的支气管肺发育不良的早产儿的现有数据集进行了分析。采用非侵入性配对测量吸入氧分数 (F _I O ₂ ) 和经皮氧饱和度 (SpO ₂ ) 来计算右向左分流程度、F _I O ₂相对于 SpO ₂的右移曲线和 V _A /Q。

结果

共有 75 名婴儿（43 名男性）在 7（2-31）天时进行了研究，中位孕龄（IQR）为 26.4（24.7-27.7）周。36 名婴儿 (48%) 的动脉 CO ₂分压(PaCO ₂ ) 高于 6 kPa。PaCO ₂与曲线右移独立相关[调整后的 p < 0.001，非标准化系数；2.26，95% CI：1.51–2.95]和从右向左分流[调整后的p = 0.016，非标准化系数；1.86, 95% CI: 0.36–3.36] 调整混杂因素后。PaCO ₂从5 kPa增加到8 kPa，对应于曲线右移20.2 kPa或V _A /Q从0.66减少到0.24。

结论

二氧化碳水平升高与患有呼吸窘迫综合征或支气管肺发育不良的早产儿氧合受损显着相关。