470 likes | 1.33k Views
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”.
E N D
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.