过度换气对犬肺循环及血栓素前列环素平衡的影响

Evaluation of Effect of Hyperventilation on Pulmonary Circulation and Balance between Thromboxane A_2 and Prostacyclin in Dogs

观察１５只正常犬在自主呼吸、正常机械通气、过度换气、纠正呼碱及注射消炎痛等五个阶段中肺循环改变及ＴＸＢ２、６－ｋｅｔｏ－ＰＧＦ（１α）改变情况，并探讨其相互间的关系。结果表明：过度换气可降低正常犬肺动脉压［２．７６５±０．７９１／２．５５１±０．６５０ｋＰａ（１ｋＰａ＝７．５ｍｍＨｇ），Ｐ＜０．００１］及心输出量（２．３２９±０．７８０／２．１３１±０．６３３Ｌ／ｍｉｎ，Ｐ＜０．０５），且二者间显著相关（ｒ＝０．６１９２，Ｐ＜０．０２）；呼吸频率改变引起过度换气时ＴＸＡ２水平无变化，而ＰＧＩ２由３３．４±１８．２ｐｇ／ｍｌ上升４７．８±１９．４ｐｇ／ｍｌ（Ｐ＜０．０５），ＴＸＡ２／ＰＧＩ２降低（４．４８±２．２０／２．６６±１．７１，Ｐ＜０．００５），但这些变化与正常肺过度换气时肺动脉压的下降无相关关系（ｒ＝０．２０２２，Ｐ＞０．０５）；呼吸性碱中毒对ＰＧＩ２合成和释放亦无影响。

Fifteen healthy dogs were subjected to hyperventilation (HV) studies.Data of blood-gas analyses, hemodynamics and blood contents of TXA2 and PGI2 were obtained respectively during the periods of spontaneous respiration,mchanical normal ventilation, mechanical HV,HV with normal PaCO2, and infusion of indomathacin. The results indicated that during HV, the pulmonary artery pressure(PAP)and cardiac output (CO)decreased significantly from 2. 765±0.791 to 2.551±0.650kPa (P<0.001)and 2.329±0.780 to 2.131±0.633L/min(P<0. 05)respectively.The reduction of PAP correlated with decrease in CO(r=0. 6192, P<0. 02). Suggest that the decreaes in CO was the main cause of reduction of PAP.EXB2(TXA2 hydrolysis product) level remined unchanged,while 6-keto-PGF1α(prostacyclin hydrolysis product)level increased significantly from 33.4±18 .2pg/ml to 47. 8±19.4(P<0.05) during HV.As a result,the ratio of TXB2 and 6-keto-PGF1α(T/6)decreased significantly from 4. 48±2.20 to 2. 66±1.71(P<0. 05 ).This result suggested that HV perse,did influence the generation and release of PGI2,but not the induced respiratory alkalosis.Change of PAP,however,had no correlation with the ratio of T/6(r=0.2022,P>0. 05).