Kirshbom P M, Skaryak L R, DiBernardo L R, Kern F H, Greeley W J, Gaynor J W, Ungerleider R M
Department of Surgery, Duke University Medical Center, Durham, N.C. 27710, USA.
J Thorac Cardiovasc Surg. 1996 Jan;111(1):147-55; discussion 156-7. doi: 10.1016/S0022-5223(96)70411-7.
Cardiopulmonary bypass with deep hypothermic circulatory arrest increases the risk of neurologic injury in patients with aortopulmonary collaterals. Experimental studies have demonstrated that such collaterals decrease the rate of cerebral cooling before arrest and cerebral metabolic recovery after circulatory arrest. Use of pH-stat blood gas management has been shown to increase cerebral blood flow during cooling. The current study was designed to test whether cooling with pH-stat blood gas management can decrease the cerebral metabolic impact of aortopulmonary collaterals. Twenty 4- to 6-week-old piglets underwent placement of a shunt between the left subclavian artery and main pulmonary artery. In control animals (n = 10) the shunts were immediately ligated, whereas in the shunt animals (n = 10) the shunts were left patent. All animals were supported with cardiopulmonary bypass, cooled to 18 degrees C by means of either alpha-stat (five control and five shunt animals) or pH-stat (five control and five shunt animals) blood gas management, subjected to circulatory arrest for 90 minutes, and rewarmed to 37 degrees C. The cerebral metabolic rate of oxygen consumption (a marker for neurologic function) was significantly lower after circulatory arrest in the shunt animals cooled with alpha-stat blood gas management than in the control animals subjected to alpha-stat management (1.2 +/- 0.2 vs 2.3 +/- 0.2 ml oxygen per 100 gm/min, p < 0.05). By contrast, there was no difference between the pH-stat shunt animals and either control group (2.1 +/- 0.2 vs 2.3 +/- 0.2 [alpha-stat] and 2.0 +/- 0.3 [pH-stat] ml oxygen per 100 gm/min, p = not significant). pH-Stat cooling protected the brain from shunt-related injury. When circulatory arrest is used in the presence of aortopulmonary collaterals, the use of pH-stat blood gas management during cooling results in better cerebral protection than alpha-stat blood gas management.
伴有深低温停循环的体外循环会增加存在主肺动脉侧支循环患者发生神经损伤的风险。实验研究表明，此类侧支循环会降低停循环前的脑冷却速率以及循环停滞后的脑代谢恢复速率。已证实采用pH稳态血气管理可在降温期间增加脑血流量。本研究旨在测试采用pH稳态血气管理进行降温是否可降低主肺动脉侧支循环对脑代谢的影响。20只4至6周龄的仔猪接受了左锁骨下动脉与主肺动脉之间分流装置的植入。在对照动物（n = 10）中，分流装置立即结扎，而在分流动物（n = 10）中，分流装置保持开放。所有动物均接受体外循环支持，通过α稳态（五只对照动物和五只分流动物）或pH稳态（五只对照动物和五只分流动物）血气管理冷却至18℃，进行90分钟的循环停搏，然后复温至37℃。在采用α稳态血气管理进行冷却的分流动物中，循环停滞后的脑氧耗代谢率（神经功能的一个指标）显著低于采用α稳态管理的对照动物（每100克/分钟1.2±0.2毫升氧气与2.3±0.2毫升氧气，p < 0.05）。相比之下，pH稳态分流动物与任一对照组之间均无差异（每100克/分钟2.1±0.2毫升氧气与2.3±0.2 [α稳态]和2.0±0.3 [pH稳态]毫升氧气，p = 无显著性差异）。pH稳态冷却可保护大脑免受分流相关损伤。当在存在主肺动脉侧支循环的情况下使用循环停搏时，降温期间采用pH稳态血气管理比α稳态血气管理能提供更好的脑保护。
