Norwood Part 1: Pre-Operative Physiology & Management with Dr. Greg Yurasek
May 29, 2023
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Dr. Greg Yurasek, a pediatric cardiology fellowship graduate, discusses topics such as single ventricle physiology, timing of procedures, assessing blood flow in pediatric patients, and pre-operative feeding challenges for single-ventricle patients.
Administering prostaglandin before the Norwood procedure in single ventricle patients is crucial to maintain systemic oxygen delivery by keeping the ductus arteriosus open.
When evaluating preoperative single ventricle patients, clinicians should assess the patient's overall appearance, pulses, capillary refill, and respiratory status to determine if adequate systemic and pulmonary blood flow is achieved.
Deep dives
Preoperative considerations for single ventricle patients
Prior to the Norwood procedure, single ventricle patients, such as those with hypoplastic left heart syndrome, require specific preoperative care. One essential step is to administer prostaglandin to keep the ductus arteriosus open, allowing for sufficient systemic oxygen delivery. Diagnostic workup, including brain imaging and genetic assessments, is performed while waiting for the pulmonary vascular resistance to decrease. Close monitoring of the patient's overall appearance, including capillary refill, feeding tolerance, and respiratory status, is crucial. Oral feeding is often initiated, although tube feeding is generally avoided. Diuretics may be used to manage pulmonary edema and optimize respiratory function. The goal is to ensure the stable transition of the patient and establish a baseline before proceeding with the Norwood procedure.
Assessing systemic and pulmonary blood flow in preoperative patients
When evaluating a preoperative single ventricle patient, the focus is on determining if systemic and pulmonary blood flow is adequate. Saturation levels alone do not provide a complete picture of oxygen delivery, so clinicians assess the patient's overall clinical appearance, pulses, capillary refill, and respiratory status. An over-circulated state, characterized by excessive pulmonary blood flow, is to be expected in these patients. The key question is whether adequate systemic oxygen delivery is being achieved. Lactate levels can also be monitored, but they are not the sole indicator of oxygen delivery. The use of medication, such as neuromuscular blockade and sub-atmospheric gas, can assist in optimizing oxygen delivery and managing excessive pulmonary blood flow when needed. Clinicians must communicate closely with surgeons to determine the appropriate timing for surgery.
Ventilation strategies for optimizing oxygen delivery
In preoperative single ventricle patients, intubation and mechanical ventilation can help optimize oxygen delivery by reducing the patient's oxygen demand. Intubation allows for muscle relaxation and decreases the energy expenditure associated with breathing. By ventilating at or slightly above functional residual capacity, clinicians can improve oxygen delivery. Adjusting ventilation settings, such as lowering the respiratory rate and maintaining normal tidal volumes, can reduce oxygen demand and improve stability. Exploring approaches such as using sub-atmospheric gas or hypoxic gas (FIO2 less than 21%) can be effective in regulating pulmonary vascular resistance and enhancing systemic oxygen delivery. These strategies should be implemented with caution and are considered temporary measures until the patient can undergo surgical intervention.
Feeding considerations and concerns
Feeding practices in preoperative single ventricle patients vary among institutions, but evidence supports the safety of limited oral feeding. Oral feeding is generally encouraged, allowing the child to determine their feeding capacity and tolerance. However, tube feeding can present risks due to uncertain organ perfusion and compromised splanchnic blood flow. Neonatal concerns regarding tube feeding should be considered, even though their specific findings may not directly apply to the cardiac intensive care unit. Caution should be exercised when deciding feeding routes in these patients, and a collaborative approach between neonatal and cardiac teams is essential.
Dr. Yurasek is a graduate of the Columbia University College of Physicians and Surgeons. He completed his pediatric residency at Children’s Hospital of Boston followed by a pediatric cardiology fellowship also at Boston Children’s and a PICU fellowship at Massachusetts General Hospital. He is now a CICU attending and the director of critical care simulation at Children’s National Hospital in Washington, DC.
Objectives for this series: 1. Understand the physiologic considerations that influence preoperative care in the cardiac intensive care unit (CICU). 2. Recall the goals and general steps of operative repair. 3. Recognize the key information provided in post-op handoff that will affect management. 4. Recognize important postoperative complications and develop an approach to their management. 5. Develop a mental framework of the expected postoperative CICU course with a focus on barriers to ICU discharge.
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Thank you for listening to this episode of PedsCrit. Please remember that all content during this episode is intended for educational and entertainment purposes only. It should not be used as medical advice. The views expressed during this episode by hosts and our guests are their own and do not reflect the official position of their institutions. If you have any comments, suggestions, or feedback-you can email us at pedscritpodcast@gmail.com. Check out http://www.pedscrit.comfor detailed show notes. And visit @critpeds on twitter and @pedscrit on instagram for real time show updates.
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