肺萎陷与气体交换的相关性——一项针对绵羊和猪正常肺脏发生肺不张的计算机断层扫描研究。
Correlation of lung collapse and gas exchange - a computer tomographic study in sheep and pigs with atelectasis in otherwise normal lungs.
作者信息
Wolf Samuel J, Reske Alexander P, Hammermüller Sören, Costa Eduardo L V, Spieth Peter M, Hepp Pierre, Carvalho Alysson R, Kraßler Jens, Wrigge Hermann, Amato Marcelo B P, Reske Andreas W
机构信息
Department of Anaesthesiology and Intensive Care Medicine, University Hospital Leipzig, Leipzig, Germany.
Anaesthesiology and Intensive Care Medicine, Fachkrankenhaus Coswig, Coswig/Meißen, Germany.
出版信息
PLoS One. 2015 Aug 10;10(8):e0135272. doi: 10.1371/journal.pone.0135272. eCollection 2015.
BACKGROUND
Atelectasis can provoke pulmonary and non-pulmonary complications after general anaesthesia. Unfortunately, there is no instrument to estimate atelectasis and prompt changes of mechanical ventilation during general anaesthesia. Although arterial partial pressure of oxygen (PaO2) and intrapulmonary shunt have both been suggested to correlate with atelectasis, studies yielded inconsistent results. Therefore, we investigated these correlations.
METHODS
Shunt, PaO2 and atelectasis were measured in 11 sheep and 23 pigs with otherwise normal lungs. In pigs, contrasting measurements were available 12 hours after induction of acute respiratory distress syndrome (ARDS). Atelectasis was calculated by computed tomography relative to total lung mass (Mtotal). We logarithmically transformed PaO2 (lnPaO2) to linearize its relationships with shunt and atelectasis. Data are given as median (interquartile range).
RESULTS
Mtotal was 768 (715-884) g in sheep and 543 (503-583) g in pigs. Atelectasis was 26 (16-47) % in sheep and 18 (13-23) % in pigs. PaO2 (FiO2 = 1.0) was 242 (106-414) mmHg in sheep and 480 (437-514) mmHg in pigs. Shunt was 39 (29-51) % in sheep and 15 (11-20) % in pigs. Atelectasis correlated closely with lnPaO2 (R2 = 0.78) and shunt (R2 = 0.79) in sheep (P-values<0.0001). The correlation of atelectasis with lnPaO2 (R2 = 0.63) and shunt (R2 = 0.34) was weaker in pigs, but R2 increased to 0.71 for lnPaO2 and 0.72 for shunt 12 hours after induction of ARDS. In both, sheep and pigs, changes in atelectasis correlated strongly with corresponding changes in lnPaO2 and shunt.
DISCUSSION AND CONCLUSION
In lung-healthy sheep, atelectasis correlates closely with lnPaO2 and shunt, when blood gases are measured during ventilation with pure oxygen. In lung-healthy pigs, these correlations were significantly weaker, likely because pigs have stronger hypoxic pulmonary vasoconstriction (HPV) than sheep and humans. Nevertheless, correlations improved also in pigs after blunting of HPV during ARDS. In humans, the observed relationships may aid in assessing anaesthesia-related atelectasis.
背景
肺不张可引发全身麻醉后的肺部及非肺部并发症。遗憾的是，目前尚无用于评估肺不张以及在全身麻醉期间及时改变机械通气的仪器。尽管动脉血氧分压（PaO2）和肺内分流均被认为与肺不张相关，但研究结果并不一致。因此，我们对这些相关性进行了研究。
方法
对11只绵羊和23头肺部正常的猪测量分流、PaO2和肺不张情况。对于猪，在诱导急性呼吸窘迫综合征（ARDS）12小时后进行对比测量。通过计算机断层扫描计算相对于总肺质量（Mtotal）的肺不张情况。我们对PaO2进行对数转换（lnPaO2）以使其与分流和肺不张的关系线性化。数据以中位数（四分位间距）表示。
结果
绵羊的Mtotal为768（715 - 884）g，猪的Mtotal为543（503 - 583）g。绵羊的肺不张为26（16 - 47）%，猪的肺不张为18（13 - 23）%。绵羊在吸入氧浓度（FiO2）= 1.0时的PaO2为242（106 - 414）mmHg，猪的为480（437 - 514）mmHg。绵羊的分流为39（29 - 51）%，猪的为15（11 - 20）%。在绵羊中，肺不张与lnPaO2（R2 = 0.78）和分流（R2 = 0.79）密切相关（P值<0.0001）。在猪中，肺不张与lnPaO2（R2 = 0.63）和分流（R2 = 0.34）的相关性较弱，但在诱导ARDS 12小时后，lnPaO2的R2增至0.71，分流的R2增至0.72。在绵羊和猪中，肺不张的变化与lnPaO2和分流的相应变化均密切相关。
讨论与结论
在肺部健康的绵羊中，当用纯氧通气时测量血气，肺不张与lnPaO2和分流密切相关。在肺部健康猪中，这些相关性明显较弱，可能是因为猪的低氧性肺血管收缩（HPV）比绵羊和人类更强。然而，在ARDS期间HPV减弱后，猪的相关性也有所改善。在人类中，观察到的这些关系可能有助于评估与麻醉相关的肺不张。
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