Kurth C D, O'Rourke M M, O'Hara I B
Department of Anesthesiology and Critical Care Medicine, Children's Hospital of Philadelphia, University of Pennsylvania School of Medicine 19104, USA.
Anesthesiology. 1998 Jul;89(1):110-8. doi: 10.1097/00000542-199807000-00018.
Deep hypothermic circulatory arrest is used in neonatal cardiac surgery. Recent work has suggested improved neurologic recovery after deep hypothermic arrest with pH-stat cardiopulmonary bypass (CPB) compared with alpha-stat CPB. This study examined cortical oxygen saturation (ScO2), cortical blood flow (CBF), and cortical physiologic recovery in relation to deep hypothermic arrest with alpha-stat or pH-stat CPB.
Sixteen piglets were cooled with pH-stat or alpha-stat CPB to 19 degrees C (cortex) and subjected to 60 min of circulatory arrest, followed by CPB reperfusion and rewarming and separation from CPB. Near infrared spectroscopy and laser Doppler flowmetry were used to monitor ScO2 and CBF. Cortical physiologic recovery was assessed 2 h after the piglets were separated from CPB by cortical adenosine triphosphate concentrations, cortical water content, CBF, and ScO2.
During CPB cooling, ScO2 increased more with pH-stat than with alpha-stat bypass (123 +/- 33% vs. 80 +/- 25%); superficial and deep CBF were also greater with pH-stat than with alpha-stat bypass (22 +/- 25% vs. -56 +/- 22%, 3 +/- 19% vs. -29 +/- 28%). During arrest, ScO2 half-life was greater with pH-stat than with alpha-stat bypass (10 +/- 2 min vs. 7 +/- 2 min), and cortical oxygen consumption lasted longer with pH-stat than with alpha-stat bypass (36 +/- 8 min vs. 25 +/- 8 min). During CPB reperfusion, superficial and deep CBF were less with alpha-stat than with pH-stat bypass (-40 +/- 22% vs. 10 +/- 39%, -38 +/- 28% vs. 5 +/- 28%). After CPB, deep cortical adenosine triphosphate and CBF were less with alpha-stat than with pH-stat bypass (11 +/- 6 pmole/mg vs. 17 +/- 8 pmole/mg, -24 +/- 16% vs. 16 +/- 32%); cortical water content was greater with alpha-stat than with pH-stat bypass (superficial: 82.4 +/- 0.3% vs. 81.8 +/- 1%, deep: 79.1 +/- 2% vs. 78 +/- 1.6%).
Cortical deoxygenation during hypothermic arrest was slower after pH-stat CPB. pH-stat bypass increased the prearrest ScO2 and arrest ScO2 half-life, to increase the cortical oxygen supply and slow cortical oxygen consumption. Improved cortical physiologic recovery after hypothermic arrest was suggested with pH-stat management.
深度低温循环停止用于新生儿心脏手术。近期研究表明，与α-stat体外循环（CPB）相比，pH-stat体外循环下深度低温停循环后神经功能恢复有所改善。本研究探讨了与α-stat或pH-stat体外循环下深度低温停循环相关的皮质氧饱和度（ScO2）、皮质血流量（CBF）及皮质生理恢复情况。
16只仔猪通过pH-stat或α-stat体外循环冷却至19℃（皮质），进行60分钟循环停止，随后进行体外循环再灌注、复温并脱离体外循环。采用近红外光谱和激光多普勒血流仪监测ScO2和CBF。仔猪脱离体外循环2小时后，通过皮质三磷酸腺苷浓度、皮质含水量、CBF和ScO2评估皮质生理恢复情况。
在体外循环降温期间，pH-stat体外循环时ScO2升高幅度大于α-stat体外循环（123±33%对80±25%）；pH-stat体外循环时浅部和深部CBF也高于α-stat体外循环（22±25%对-56±22%，3±19%对-29±28%）。在停循环期间，pH-stat体外循环时ScO2半衰期长于α-stat体外循环（10±2分钟对7±2分钟），且pH-stat体外循环时皮质氧消耗持续时间长于α-stat体外循环（36±8分钟对25±8分钟）。在体外循环再灌注期间，α-stat体外循环时浅部和深部CBF低于pH-stat体外循环（-40±22%对10±39%，-38±28%对5±28%）。体外循环后，α-stat体外循环时深部皮质三磷酸腺苷和CBF低于pH-stat体外循环（11±6皮摩尔/毫克对17±8皮摩尔/毫克，-24±16%对16±32%）；α-stat体外循环时皮质含水量高于pH-stat体外循环（浅部：82.4±0.3%对81.8±1%，深部：79.1±2%对78±1.6%）。
pH-stat体外循环后低温停循环期间皮质脱氧较慢。pH-stat体外循环增加了停循环前ScO2及停循环时ScO2半衰期，以增加皮质氧供应并减缓皮质氧消耗。提示pH-stat管理可改善低温停循环后皮质生理恢复。
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