Department of Medical Sciences, Clinical Physiology, University of Uppsala, Uppsala, Sweden.
Acta Anaesthesiol Scand. 2011 Aug;55(7):887-96. doi: 10.1111/j.1399-6576.2011.02464.x. Epub 2011 Jun 20.
CO(2) -pneumoperitoneum (PP) is performed at varying abdominal pressures. We studied in an animal preparation the effect of increasing abdominal pressures on gas exchange during PP.
Eighteen anaesthetized pigs were studied. Three abdominal pressures (8, 12 and 16 mmHg) were randomly selected in each animal. In six pigs, single-photon emission computed tomography (SPECT) was used for the analysis of V/Q distributions; in another six pigs, multiple inert gas elimination technique (MIGET) was used for assessing V/Q matching. In further six pigs, computed tomography (CT) was performed for the analysis of regional aeration. MIGET, CT and central haemodynamics and pulmonary gas exchange were recorded during anaesthesia and after 60 min on each of the three abdominal pressures. SPECT was performed three times, corresponding to each PP level.
Atelectasis, as assessed by CT, increased during PP and in proportion to abdominal pressure [from 9 ± 2% (mean ± standard deviation) at 8 mmHg to 15 ± 2% at 16 mmHg, P<0.05]. SPECT during increasing abdominal CO(2) pressures showed a shift of blood flow towards better ventilated areas. V/Q analysis by MIGET showed no change in shunt during 8 mmHg PP (9 ± 1.9% compared with baseline 9 ± 1.2%) but a decrease during 12 mmHg PP (7 ± 0.9%, P<0.05) and 16 mmHg PP (5 ± 1%, P<0.01). PaO(2) increased from 39 ± 10 to 52 ± 9 kPa (baseline to 16 mmHg PP, P<0.01). Arterial carbon dioxide (PCO(2) ) increased during PP and increased further with increasing abdominal pressures.
With increasing abdominal pressure during PP perfusion was redistributed more than ventilation away from dorsal, collapsed lung regions. This resulted in a better V/Q match. A possible mechanism is enhanced hypoxic pulmonary vasoconstriction mediated by increasing PCO(2) .
CO2 气腹（PP）在不同的腹部压力下进行。我们在动物模型中研究了增加腹部压力对 PP 期间气体交换的影响。
研究了 18 头麻醉猪。在每个动物中随机选择三个腹部压力（8、12 和 16mmHg）。在 6 头猪中，使用单光子发射计算机断层扫描（SPECT）分析 V/Q 分布；在另外 6 头猪中，使用多惰性气体消除技术（MIGET）评估 V/Q 匹配。在另外 6 头猪中，进行计算机断层扫描（CT）分析区域性通气。在麻醉期间和每个 PP 水平 60 分钟后记录 MIGET、CT 和中心血液动力学以及肺气体交换。SPECT 进行了三次，分别对应于每个 PP 水平。
CT 评估的肺不张在 PP 期间增加，并与腹部压力成正比[从 8mmHg 时的 9±2%（平均值±标准差）增加到 16mmHg 时的 15±2%，P<0.05]。随着腹部 CO2 压力的增加，SPECT 显示血流向通气较好的区域转移。MIGET 的 V/Q 分析显示，在 8mmHg 的 PP 期间，分流没有变化（9±1.9%与基线时的 9±1.2%相比），但在 12mmHg 的 PP 期间和 16mmHg 的 PP 期间，分流减少（7±0.9%，P<0.05 和 5±1%，P<0.01）。PaO2 从 39±10 增加到 52±9kPa（基础值到 16mmHg 的 PP，P<0.01）。动脉血二氧化碳（PCO2）在 PP 期间增加，随着腹部压力的增加进一步增加。
在 PP 期间，随着腹部压力的增加，灌注的分布比通气更远离背部、塌陷的肺区域。这导致了更好的 V/Q 匹配。一种可能的机制是由 PCO2 增加介导的缺氧性肺血管收缩增强。
