2024 FSA Podium and Poster Abstracts

P035: OH NO, DON'T GIVE THAT BABY OXYGEN!
Alexandra L Carroll, MD; Sonia Mehta, MD; University of Florida Gainesville

Introduction/Background:  Tetralogy of Fallot is a congenital heart defect that is comprised of four anomalies of the heart. A large ventricular septal defect, a stenotic outflow tract of the pulmonary artery and/or pulmonary valve, overriding aorta, and right ventricular hypertrophy. Due to mixing of oxygenated blood via the ventricular septal defect, affected patients typically have a lower baseline SpO2. During periods of agitation, a patient may have a decrease in systemic vascular resistance or increase in pulmonary vascular resistance creating a worsening right-to-left shunt. This means that less blood will be oxygenated via the pulmonary circulation and may result in extreme cyanosis. This is otherwise known as a Tet Spell and is a true emergency. We are presenting a case where an infant with uncorrected Tetralogy of Fallot was administer supplemental oxygen and continued to have oxygen desaturation.

Methods: This is a case report of a young patient who was found to be desaturating in the OR prior to induction. The patient was very upset and appeared to be suffering from a Tet Spell as they were noted to be cyanotic. The anesthesia provider started supplemental oxygen via nasal cannula when SpO2 saturation was noted to be in the 80s. The patient’s history of unrepaired Tetralogy of Fallot was shared with the physician and decision was made to take off supplemental oxygen.

Results: Patient was noted to be very agitated prior to induction and during this time they became increasing cyanotic. Supplemental oxygen was given via nasal canula; however, not only did the SpO2 not improve but rather became worse. The patient became more agitated from the nasal canula and was difficult to console. Following removal of supplemental oxygen and calming the patient down, oxygen saturation levels improved.

Discussion/Conclusion: This patient’s history of Tetralogy of Fallot is crucial for anesthetic decision making. It is important to understand that this patient’s baseline SpO2 is likely below 90% due to mixing of oxygenated and deoxygenated blood via the ventricular septal defect. Furthermore, supplemental oxygen will likely not make a significant improvement in SpO2 because of this mixing. Only after surgical repair will this patient have a more normal SpO2. Additionally, supplemental oxygen will cause a decrease in pulmonary vascular resistance leading to mixed blood being shunted into the pulmonary circulation and away from the systemic circulation further worsening delivery of oxygenated blood to the rest of the body. It is also critical to try and alleviate the patient’s agitation when undergoing a Tet Spell so that they may return to their baseline cardiac function and oxygen saturation as happened with this patient when the nasal cannula was removed and they were consoled. This case demonstrates the importance of understanding a patient’s cardiac history and pathophysiology to provide a safe anesthetic and maintain hemodynamic stability.