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This curriculum focuses on postoperative care in congenital heart disease patients in the PICU, emphasizing the importance of maximizing oxygen delivery for patient homeostasis. The comprehensive program covers general principles, cardiovascular guidelines, respiratory management approaches, pain control, metabolic considerations, and infection prevention. It highlights the interconnection of various parameters and the impact of surgical interventions, guiding residents on specific strategies to optimize patient outcomes.
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UTHSCSA Pediatric Resident Curriculum for the PICU Postoperative Care in the Patient With Congenital Heart Disease
General Principles • Patient homeostasis • Early – declining trends do not correct themselves • Late – time can be important diagnostic tool “The enemy of good is better”
Specific Approaches • Cardiovascular principles • Approach to respiratory management • Pain control/sedation • Metabolic/electrolytes • Infection • Effects of surgical interventions on these parameters NO PARAMETER EXISTS IN ISOLATION
Cardiovascular Principles • Maximize O2 delivery/ O2consumption ratio • Oxygen delivery: • Cardiac Output • Ventilation/Oxygenation • Hemoglobin
Maximizing Oxygen Delivery Metabolic acidosis is the hallmark of poor oxygen delivery
OXYGEN DELIVERY CARDIAC OUTPUT OXYGEN CONTENT X = Maximizing Oxygen Delivery
Maximizing Oxygen DeliveryCardiac Output O2 Content = Saturation(O2 Capacity)+(PaO2)0.003 • Oxygen Capacity = Hgb (10) (1.34) • So . . • Hemoglobin and saturations are determinants of O2 delivery
Maximizing Oxygen DeliveryCardiac Output Gidding SS et al 1988 y=-0.26(x)+38 R=0.77 S.E.E.=1.6
Stroke Volume Contractility Diastolic Filling Afterload Heart rate Physiologic Response Non-physiologic Response Sinus vs. junctional vs. paced ventricular rhythm Cardiac Output Heart Rate Stroke Volume X = Maximizing Oxygen DeliveryCardiac Output
Maximizing Oxygen • Oxygen consumption • Decreasing metabolic demands • Sedation/ paralysis • Thermoregulation
Ventilator Strategies • Respiratory acidosis/hypercarbia • Oxygenation • Physiology of single ventricle/shunt lesions • Oxygen delivery! • Atelectasis – 15-20 cc/kg tidal volumes. • PEEP, inspiratory times
Ventilator Strategies:Pulmonary Hypertension • Sedation/neuromuscular blockade • High FiO2 – no less than 60% FiO2 • Mild respiratory alkalosis • pH 7.50-7.60 • pCO2 – 30-35 mm Hg • Nitric Oxide
Ventilator Strategies: Pulmonary Hypertension Precipitating Event -Cold stress -Suctioning -Acidosis The viscious cycle of PHTN Metabolic Acidosis Hypercapnia Increased PVR Decreased Pulmonary Blood Flow Decreased LV preload RV dysfunction Central Venous Hypertension Hypoxemia Low output Ischemia
Pain Control/Sedation • Stress response attenuation • Limited myocardial reserve – decreasing metabolic demands • Labile pulmonary hypertension • Analgesia/anxiolysis
Pain Control/Sedation Opioids • MSO4 – Gold standard: better sedative effects than synthetic opioids • Cardioactive – histamine release and limits endogenous catecholamines • Fentanyl/sufentanyl • Less histamine release • More lipid soluble – better CNS penetration
Pain Control/Sedation Sedatives • Chloral hydrate • Can be myocardial depressant • Metabolites include trichloroethanol and trichloroacetic acid • Benzodiazepines • Valium/Versed/Ativan
Pain Control/Sedation Muscle relaxants • Depolarizing – Succinylcholine • Bradycardia ( ACH) • Non-depolarizing • Pancuronium – tachycardia • Vecuronium – shorter duration • Atracurium • “spontaneously” metabolized • Histamine release
Pain Control/Sedation Others: • Barbiturates – vasodilation, cardiac depression • Propofol – myocardial depression, metabolic acidosis • Ketamine – increases SVR • Etomidate – No cardiovascular effects
Fluid and Electrolytes • Effects of underlying cardiac disease • Effects of treatment of that disease
Cardiopulmonary Bypass • “Controlled shock” • Loss of pulsatile blood flow • Capillary leak • Vasoconstriction • Renovascular effects • Renin/angiotensin • Cytokine release • Endothelial damage and “sheer injury”
Lung Fluid Filtration = [( )-( )] Microvascular Hydrostatic Pressure Microvascular Oncotic Pressure Cardiopulmonary Bypass Stress Response Microembolic Events SIRS Renal Insufficiency Fluid Administration Hemorrhage Capillary Leak Syndrome Feltes, 1998
Circulatory Arrest • Hypothermic protection of brain and other tissues • Access to surgical repair not accessible by CPB alone • Further activation of SIRS/ worsened capillary leak.
Fluid and Electrolyte Principles • Crystalloid • Total body fluid overload • Maintenance fluid = 1500-1700 cc/m2/day • Fluid advancement: • POD 0 : 50-75% of maintenance • POD 1 : 75% of maintenance • Increase by 10% each day thereafter
Fluid and Electrolyte Principles Flushes and Cardiotonic Drips • Remember: Flushes and Antibiotics = Volume UTHSCSA protocol to minimize crystalloid: Standard Drip Concentration Mix in dextrose or saline containing fluid to optimize serum glucose & electrolytes Sedation: (Used currently as carrier for drips) MSO4 2cc/hr = 0.1 mg/kg/hr Fentanyl 2 cc/hr = 3 mcg(micrograms)/kg/hr Cardiotonic medications: Dopamine/Dobutamine 50 mg/50 cc Epi/Norepinephrine 0.5 mg/50 cc Milrinone 5 mg/50 cc Nipride (Nitroprusside) 0.5 mg/50 cc Nitroglycerin 50 mg/50 cc PGEI 500 mcg/50 cc
Fluid and Electrolyte Principles • Intravascular volume expansion/ Fluid challenges • Colloid – osmotically active • FFP • 5% albumin/25% albumin • PRBC’s • HCT adequate: 5% albumin (HR, LAP, CVP) • HCT inadequate: 5-10 cc/kg PRBC • Coagulopathic: FFP/ Cryoprecipitate • Ongoing losses: CT and Peritoneal frequently = 5% albumin
Metabolic Effects • Glucose • Neonates vs. children/adults • Hyperglycemia in the early post-op period
Metabolic Effects • Calcium • Myocardial requirements • Rhythm • Contractility • Vascular resistance NEVER UNDERESTIMATE THE POWER OF CALCIUM!
Alpha 1 DAG Phosphodiesterase Adenylate Cyclase Beta 1 IP3 cAMP cAMP Sarcoplasmic Reticulum Regulatory G Protein Na cAMP Ca cAMP-Dependent PK Ca K Ca SR Na Ca Ca Myofibril Calcium/inotropes
Metabolic Effects • Potassium • Metabolic acidosis • Rhythm disturbances
Thermal Regulation As a sign to watch, and an item to manipulate… • Perfusion • Junctional ectopic tachycardia • Metabolic demands • Oxygen consumption • Infection
Infection • Routine anti-staphylococcal treatment
Effects of Surgical Interventions • Cardiopulmonary Bypass vs. Non-Bypass • Fluids and electrolytes • Modified ultrafiltration • Types of anatomic defects • Overcirculated – increased blood volumes preoperatively • Undercirculated – reperfusion of area previously experiencing much reduced flow volumes.
Summary • Optimize oxygen delivery by manipulation of cardiac output and hemoglobin • Sedation and pain control can aid in the recovery • Appreciate effects of cardiopulmonary bypass and circulatory arrest on fluid and electrolyte management • Tight control of all parameters within the first 12 hours; after that time, patients may be better able to declare trends that can guide your interventions.