Korean J Anesthesiol.  1999 Sep;37(3):496-502. 10.4097/kjae.1999.37.3.496.

The Effects of Cardiac Bypass Method on the Change of Hemodynamics and Gas Exchange in Fetal Lamb Model under Ketamine Anesthesia

• Ro YJ
• Kim CS
• Kim YJ
• Kim WG
• Lee JR
• Choi JY

• KMID: 2240054
• DOI: http://doi.org/10.4097/kjae.1999.37.3.496

Abstract

BACKGROUND: Intrauterine surgical intervention for certain cardiac anomalies may have a therapeutic advantage over postnatal repair or palliation. However, it is essential to establish methods for intrauterine extracorporeal circulation and myocardial preservations which can maintain the hemodynamics and gas exchange in fetal lamb perioperatively. This study was aimed to observe the changes in hemodynamics and gas exchange according to the methods of fetal cardiac bypass.
METHODS
Twelve fetal lambs (4.5 5.2 kg) at 120 to 150 days of gestation under ketamine anesthesia were subjected to cardiac bypass for 30 minutes. Six served as a group in which placenta was excluded from the extracorporeal circulation by clamping the umbilical cord during the bypass (the oxygenator group) and in the remaining six, the placenta worked as an in vivo oxygenator (the placenta group). The fetuses were observed every 10 minute during a 30-minute bypass and 30-minute post bypass period. The hemodynamic variables and fetal blood gases were measured at specific intervals.
RESULTS
In the oxygenator group, mean arterial pressure (MAP), PaO2, heart rate and bypass flow rate were 62 to 74 mmHg, 220 to 282 mmHg, 169 to 182 /min and 134 to 164 ml/kg/min, respectively during bypass. But rapid deterioration of fetal cardiac and placental gas exchange function was observed following cessation of bypass. In the placenta group, MAP decreased from 61 to 34 mmHg and PaCO2 progressively increased from 56 to 74 mmHg during bypass. Flow rate was suboptimal (74 to 115 ml/kg/min) during bypass. All hearts of the placenta group was fibrillated immediately after discontinuation of bypass.
CONCLUSION
The both methods of CPB, use of oxygenator and placenta as gas exchanger, under only ketamine anesthesia did not provide adequate hemodynamics and gas exchange without additional treatment for protection placental reaction. The methods of fetal cardiac bypass using either neonatal membrane oxygenator or placental as an in vivo oxygenator caused severe placental dysfunction and blood gas abnormalities.

Keyword

Anesthetics, intravenous, ketamine; Animal, lamb; Heart, cardiac bypass; Monitoring, gas exchange, hemodynamics; Surgery, fetal heart

MeSH Terms

Anesthesia*
Arterial Pressure
Constriction
Extracorporeal Circulation
Fetal Blood
Fetus
Gases
Heart
Heart Rate
Hemodynamics*
Ketamine*
Oxygen
Oxygenators
Oxygenators, Membrane
Placenta
Pregnancy
Umbilical Cord
Gases
Ketamine
Oxygen