TYK210
A 7-month old, 7 kg, male is undergoing definitive repair of tetralogy of Fallot. He has had previous palliative surgery to place a modified Blalock-Taussig shunt (MBTS). CPB has been initiated uneventfully, and the surgeon is preparing to isolate and clamp the BT shunt. You note that the cerebral NIRS value has drifted down, and also note that the MAP is 30. The following will improve these changes EXCEPT:
a) Increasing CPB flow rates
b) Transfusing packed red blood cells
c) Clamping the BT shunt
d) Giving a bolus of phentolamine into the CPB reservoir
e) Decreasing volatile agent on the CPB circuit
Answer
Answer d. Hypotension on CPB may be due to low flow rates, hemodilution, or collateral shunts. High concentrations of volatile agent administered into the CPB circuit may also contribute to the fall in MAP. A small incremental dose of vasoconstrictor, such as phenylephrine, can be given if improvement is not seen. A vasodilator such as phentolamine would be expected to decrease blood pressure for this patient.
Notes
- This question originally printed in the Pediatric Anesthesiology Review Topics kindle book series, and appears courtesy of Naerthwyn Press, LLC.