Korean J Thorac Cardiovasc Surg.  1999 Jun;32(6):495-503.

Experimental Fetal Cardiopulmonary Bypass in the Fetal Lamb Model

• Lee JR
• Lim HG
• Kim WG
• Kim JS
• Chui JY
• Kim YJ

Abstract

BACKGROUND: We tested the technical feasibility of fetal cardiac bypass and collected baseline data on the fetal hemodynamics and placental functions related to the cardiopulmonary bypass in the fetal lamb model. MATERIAL AND METHOD: Eleven fetuses at 120 to 150 days of gestation were subjected to bypass via trans-sternal approach with a 12 G pulmonary arterial cannula and 14 to 18 F venous cannula for 30 minutes. All ewes received general anesthesia with ketamine. In all the fetuses, no anesthetic agents were used except muscle relaxant. Eight 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 three, the placenta worked as the only source of oxygen supply(the placenta group). Observations were made every 10 minute during a 30-minute bypass and 30-minute post bypass period. No prostaglandin inhibitors were used both in ewes and in fetuses. RESULT: Weights of the fetuses ranged from 1.9 to 5.2 kg. In the oxygenator group, means of arterial pressure, PaO2, atrial pressure, heart rate, and bypass flow rate ranged 69.8 to 82.6 mmHg, 201.7 to 220.9 mmHg, 4.1 to 4.3 mmHg, 169 to 182/min, and 140.3 to 164.0 ml/kg/min, respectively during bypass, but rapid deterioration of the fetal cardiac functions and the placental gas exchange was observed after the cessation of bypass. In the placenta group, means of arterial pressure decreased from 44.7 to 14.4 mmHg and means of PaCO2 increased from 61.9 to 129.6 mmHg during bypass. Flow rate was suboptimal(74.3 to 97.0 ml/kg/min) during bypass. All hearts fibrillated immediately after the discontinuation of bypass.
CONCLUSION
In this study, the technical feasibility of fetal cardiopulmonary bypass was confirmed in the fetal lamb model. However, further studies with modifications of the bypass including an addition of prostaglandin inhibitor, an application of the total spinal anesthesia on the fetus, a creation of more concise bypass circuit, and a use of active pump are mandatory to improve the outcome.

Keyword

Fetus; Cardiopulmonary bypass; Model, experimental

MeSH Terms

Anesthesia, General
Anesthesia, Spinal
Anesthetics
Arterial Pressure
Atrial Pressure
Cardiopulmonary Bypass*
Catheters
Constriction
Extracorporeal Circulation
Fetus
Heart
Heart Rate
Hemodynamics
Ketamine
Models, Theoretical
Oxygen
Oxygenators
Placenta
Pregnancy
Prostaglandin Antagonists
Umbilical Cord
Weights and Measures
Anesthetics
Ketamine
Oxygen
Prostaglandin Antagonists