Memory Master Test 2 Flashcards
What hemodynamic alteration may worsen (increase flow through) a left-to-right intracardiac shunt?
Increase in SVR such as ASD
What is patent ductus arteriosus? When does the ductus arteriosus normally close?
Patent ductus arteriosus is an abnormal persistence in the newborn of blood flow through the ductus arteriosus.
Normally the ductus closes within a few hours to a few days after birth due to changes in pressures of the pulmonary vasculature
Name the physiologic factor most responsible for closure of the ductus arteriosus after birth.
Normal closure occurs in response to increased arterial oxygen tension PaO2 as well as reduction in circulating prostaglandins.
Is patent ductus arteriosus a right to left or a left to right?
Left to Right
With patent ductus arteriosus what cardiovascular changes occur?
a PDA allows blood to flow from aorta into pulmonary artery.
Additional blood is reoxygenated in the lungs and returned to the LA and LV and this causes increased workload on the left side of the heart and LV hypertrophy and increased pulmonary vascular congestion and resistance
Most patients are asymptomatic
What is the probable problem if the pediatric patient has a systolic and diastolic murmur?
Patent ductus arteriosus
A continuous systolic and diastolic murmur is often the only manifestation of PDA
Where are pulse oximeters placed on the neonate to monitor preductal and postductal oxygenation?
Preductal - Right hand or finger
Postductal - Left foot or left toe
What is the purpose of the preductal oximeter in the neonatal patient undergoing cardiac surgery?
Measurements of arterial oxygen saturation taken at a preductal location are a better index of neonatal cerebral oxygenation than are those taken at a postductal location. R to L shunt at the ductus arteriosus persists some time after birth PREDUCTAL PLACEMENT of the pulse oximeter is preferred
A POSTDUCTAL pulse oximeter can be used to quantify the degree of R to L shunt
Where should arterial blood pressure be measured in patient undergoing repair of PDA?
Peripheral artery such as femoral (POSTDUCTAL)
Does blood shunt R to L or L to R through the VSD in Tetrology of Fallot (cyanotic heart disease)?
Blood shunts R to L permitting unoxygenated blood to mix with oxygenated blood, resulting in cyanosis.
What pharmacologic agent decreases a R to L shunt?
Phenylephrine increases SVR and decreases R to L shunt.
The pediatric patient is scheduled for a radiofrequency ablation of an aberrant conduction pathway (eg WPW). What is a general anesthetic typically required for this scenario?
Anesthetic agents and technique should be chosen to maintain circulating catecholamines and avoid suppression of arrhythmogenesis.
Four defects of Tetrology of Fallot
VSD
Right Ventricular Outflow Tract obstruction
RV Hypertrophy
Overriding Aorta- dextroposition of the aorta with overriding of the VSD
Goals of anesthetic management for the patient who has TOF
Avoid PVR increases.
Maintain intravascular volume and SVR.
An infant has TOF. Which of the following arterial blood gas parameters will not typically be changed PaCO2? pH? PaO2?
pH and PaCO2 are likely to be in the normal range
PaO2 is usually markedly decreased <50mmHg
During the case, oxygen saturation decreases, apparently because of the increased shunting. The patient has TOF. What agents might be selected to decrease shunt and increase oxygen saturation?
IV fluid admin because acute hypovolemia increase the magnitude of R to L intracardiac shunt.
Alpha-agonist drug phenylephrine must be available to treat an undesired decrease in systemic blood pressure caused by a decrease in SVR.
List 3 conditions that increase R to L shunt TOF.
Acidosis
Hypercarbia
Hypotension
To what do preductal or postductal coarctation of the aorta refer?
Coarctation of the aorta refers to a discrete narrowing of aorta immediately distal to the origin of the left subclavian artery.
Preductal occurs proximal to the opening of ductus arteriosus
Postductal present in adulthood long after closure of the ductus arteriosus
Should upper extremity blood pressure be monitored in the neonate with preductal coarctation of the aorta on the right or left arm?
PREDUCTAL = RIGHT RADIAL ARTERY
Best site to get ABG from neonate?
Right radial artery
Site will also preductal oxygen saturation which better reflects cerebral oxygenation
What is the anesthetic concern for a patient undergoing repair of VSD with pulmonary HTN?
Patient often is already R to L shunting through VSD. If VSD closed before 1 year often normal ventricular function and ejection fraction.
Changes may increase PVR can cause rapid deterioration including hypoxia, hypercarbia, acidosis, hypothermia, atelectasis, sympathetic stimulation, and polycythemia.
R to L intracardiac shunt is present in a patient with VSD with Eisenmenger’s syndrome. What hemodynamic alterations may worsen (increase shunt flow) the R to L shunt of VSD with Eisenmenger’s syndrome?
An abrupt increase in PVR or decrease in SVR is poorly tolerated in VSD patients.
Avoid interventions that may increase PVR or decrease SVR in the patient with R to L intracardiac shunt.
Will a R to L shunt theoretically slow or accelerate inhalation induction? Is this clinically significant?
Slow inhalation inductions but is rarely problematic.
R to L shunt will slow or accelerate intravenous induction?
Accelerate
L to R will slow or accelerate inhalation induction
Accelerate
L to R will slow or accelerate intravenous induction
Slow
