Background

To assess the relationship between the intrapulmonary shunt and PaO₂/FiO₂ in severe hypoxemic patients after acute type A aortic dissection (ATAAD) surgery and to evaluate the effect of inhaled nitric oxide (iNO) on intrapulmonary shunt.

Methods

Postoperative ATAAD patients with PaO₂/FiO₂ ≤ 150 mmHg were enrolled. Intrapulmonary shunt was calculated from oxygen content of different sites (artery [CaO₂], mixed venous [CvO₂], and alveolar capillary [CcO₂]) using the Fick equation, where intrapulmonary shunt = (CcO₂-CaO₂)/(CcO₂-CvO₂). Related variables were measured at baseline (positive end expiratory pressure [PEEP] 5 cm H₂O), 30 min after increasing PEEP (PEEP 10 cm H₂O), 30 min after 5 ppm iNO therapy (PEEP 10 cm H₂O + iNO), and 30 min after decreasing PEEP (PEEP 5 cm H₂O + iNO).

Results

A total of 20 patients were enrolled between April 2019 and December 2019. Intrapulmonary shunt and PaO₂/FiO₂ were correlated in severe hypoxemic, postoperative ATAAD patients (adjusted R² = 0.467, p < 0.001). A mixed model for repeated measures revealed that iNO, rather than increasing PEEP, significantly decreased the intrapulmonary shunt (by 15% at a PEEP of 5 cm H₂O and 16% at a PEEP of 10 cm H₂O, p < 0.001 each) and increased PaO₂/FiO₂ (by 63% at a PEEP of 5 cm H₂O and 65% at a PEEP of 10 cm H₂O, p < 0.001 each). After iNO therapy, the decrement of intrapulmonary shunt and the increment of PaO₂/FiO₂ were also correlated (adjusted R² = 0.375, p < 0.001).

Conclusions

This study showed that intrapulmonary shunt and PaO₂/FiO₂ were correlated in severe hypoxemic, postoperative ATAAD patients. Furthermore, iNO, rather than increasing PEEP, significantly decreased the intrapulmonary shunt to improve severe hypoxemic conditions.

中文翻译：

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吸入一氧化氮减少肺内分流以改善急性 A 型主动脉夹层手术后的严重低氧血症

背景

评估急性A型主动脉夹层（ATAAD）手术后严重低氧患者肺内分流与PaO ₂ /FiO ₂的关系，并评估吸入一氧化氮（iNO）对肺内分流的影响。

方法

PaO ₂ / FiO ₂  ≤ 150 mmHg的术后ATAAD患者入组。使用 Fick 方程根据不同部位（动脉 [CaO ₂ ]、混合静脉 [CvO ₂ ] 和肺泡毛细血管 [CcO ₂ ]）的氧含量计算肺内分流，其中肺内分流 = (CcO ₂ -CaO ₂ )/( CcO ₂ -CvO ₂ )。在基线（呼气末正压 [PEEP] 5 cm H ₂ O）、增加 PEEP 后 30 分钟（PEEP 10 cm H ₂ O）、5 ppm iNO 治疗后 30 分钟（PEEP 10 cm H ₂ O + ）测量相关变量iNO) 和降低 PEEP 后 30 分钟 (PEEP 5 cm H₂ O + iNO)。

结果

2019 年 4 月至 2019 年 12 月期间，共有 20 名患者入组。肺内分流和 PaO ₂ /FiO ₂与严重低氧、术后 ATAAD 患者相关（调整后的 R ²  = 0.467，p  < 0.001）。重复测量的混合模型表明iNO的，而不是增加PEEP，显著以5cm H A PEEP降低肺内分流（15％₂ O和16％以10cm H A PEEP ₂ O，p  <每个0.001 ），增加氧分压₂ /氧合指数₂（63％在5厘米h的PEEP ₂ O和65％以10cm H A PEEP ₂ O，p < 0.001 每个）。iNO治疗后，肺内分流的减少与PaO ₂ /FiO ₂的增加也相关（调整后的R ²  = 0.375，p  < 0.001）。

结论

该研究表明，肺内分流和 PaO ₂ /FiO ₂在严重低氧血症、术后 ATAAD 患者中存在相关性。此外，iNO 并没有增加 PEEP，而是显着减少了肺内分流以改善严重的低氧血症。