Module 7: Magdalena and Michael Flashcards
The more fetuses a woman carries at once, _______ ___ ____.
the greater her risk. As the number of fetuses increase (twins, triplets, quadruplets, etc.), the risk of premature birth increases and birth weight decreases.
Common complications of twin pregnancy include:
- Premature birth
- Low Birth Weight (LBW)
- Twin-Twin Transfusion syndrome (TTTS)
- Preeclampsia
- Gestational Diabetes
Premature Birth
- About 60 percent of twins, more than 90 percent of triplets, and virtually all quadruplets and higher-order multiples are born premature.
- The length of pregnancy decreases with each additional baby. On average, most singleton pregnancies last 39 weeks; for twins, 35 weeks; for triplets, 32 weeks; and for quadruplets, 29 weeks.
Low birth weight (LBW)
- More than half of twins and almost all higher-order multiples are born with low birth weight.
- LBW can result from premature birth and/or poor fetal growth. Both are common in multiple pregnancies.
Twin-twin transfusion syndrome (TTTS)
About 10 percent of identical twins who share a placenta develop this complication. TTTS occurs when a connection between the two babies’ blood vessels in the placenta causes one baby to get too much blood flow and the other too little. TTTS can be treated with laser surgery to seal off the connection between the babies’ blood vessels.
Preeclampsia
Women expecting twins are more than twice as likely as women with a singleton pregnancy to develop this complication characterized by high blood pressure, protein in the urine and generalized edema. Severe cases can be dangerous for mother and baby. In some cases, the baby must be delivered early to prevent serious complications.
Gestational diabetes
Women carrying multiples are at increased risk of this pregnancy-related form of diabetes. This condition can cause the baby to grow especially large, increasing the risk of injuries to mother and baby during vaginal birth. Babies born to women with gestational diabetes also may have breathing and other problems during the newborn period.
Fraternal (dizygotic)
Is when two separate eggs are fertilized by two separate sperm to form two separate embryos. Fraternal twins are more common because each baby develops from a separate egg and sperm. Since each has a different egg and a different sperm, it is like siblings being born at the same time.
Identical (monozygotic)
Is where one egg is fertilized and splits to form two embryos. The fetuses share the same placenta, but they also share the same genetic material.
Monochorionic twins
Fetuses share a single placenta.
Are always identical twins.
Higher risk for complications because two fetuses have to grow on a single placenta.
Placenta is not always equally divided between the fetuses.
Each fetus’s blood circulation is connected through blood vessels in the common placenta and blood may pass disproportionately from one baby to the other, leading to the twin -twin transfusion syndrome (TTTS).
Dichorionic twins
Fetuses each have their own placenta
Most of these twins are fraternal; only a minority of these twins will be identical
Patent Ductus Arteriosus
A patent ductus arteriosus is a vascular connection that during fetal life bypasses the pulmonary vascular bed and directs blood from the pulmonary artery to the aorta (bypassing the lungs). Functional closure of the ductus normally occurs soon after birth. If the ductus remains patent after birth the direction of blood flow in the ductus is reversed (left to right) by the higher pressure aorta
What is the direction of blood flow through Magdalena’s PDA?
The direction of blood flow through Magdalena’s PDA is left to right.
From which blood vessel to which blood vessel is this blood being shunted?
Blood is flowing from the aorta into the pulmonary artery.
Why is blood being shunted in this way?
Blood is being shunted in this way because of the pressure gradient between the pulmonary artery and the aorta. This pressure gradient is such that the pressure in the aorta is higher than the pressure in the pulmonary artery. Blood flows along the path of least resistance: away from areas of higher pressure toward areas of lower pressure.
Why is PDA called an acyanotic heart defect?
Because no cyanosis results. A sufficient amount of oxygenated blood is in the circulation.
Why does a PDA cause pulmonary hyperperfusion?
A PDA allows blood to re-enter the pulmonary circuit, thereby increasing pulmonary blood flow.
Name 6 signs and symptoms of PDA you would expect to see in Magdalena?
systolic murmur – due to blood shunting through the ductus arteriosus
widening pulse pressures (difference between systolic and diastolic pressures) – increased volume of blood flowing through left heart
hypotension – due to a drop in diastolic pressure
bounding peripheral pulses – high stroke volume
active precordium – due to increased volume of blood in left heart
tachycardia – too much blood in the pulmonary capillaries which impairs gas exchange
Congestive heart failure is often listed as a sign of PDA. This is certainly true; however, it is a later sign than the six signs listed above.
What is meant by the term “conservative management” for a patent ductus arteriosus?
fluid restriction
respiratory support
administration of indomethacin or ibuprofen (NSAIDS, inhibitors of prostaglandin synthesis)
How does conservative management compare to more invasive management?
Invasive management of a PDA refers to surgical ligation.
NICUs in general try to close the PDA conservatively before resorting to surgical ligation.
If the cardiologist had suggested a course of indomethacin, what assessment data would you need to gather before you gave the first dose?
Since indomethacin is highly nephrotoxic, overall renal function, BUN, and creatinine levels must be evaluated prior to administration. Therefore, assessing fluid balance, urine output, and serum electrolytes is essential.
Indomethacin also interferes with platelet function; therefore, its use is contraindicated when an infant has a low platelet count or bleeding disorder.
Other contraindications are necrotizing enterocolitis and IVH.
Intraventricular Hemorrhage
Intraventricular Hemorrhage is the most common type of intracranial hemorrhage seen in the neonatal period. As the gestational age decreases, the risk of developing an IVH increases. This type of brain injury is “almost exclusively seen in preterm infants, particularly those weighing less those 1500 grams”
The major risk factors for IVH in the neonate are:
Prematurity
-The periventricular area of the brain is growing rapidly and is richly supplied by blood vessels.
-These blood vessels are very thin.
-Pressure autoregulation is immature:
pressure autoregulation is a physiologic mechanism that functions to prevent increases in systemic blood pressure from creating increases in cerebral blood pressure
pressure autoregulation is immature in preterm infants, meaning that any increase in systemic blood pressure creates an increase in cerebral blood pressure
Hypoxia
Recall from Sarah, that hypoxia leads to redistribution of blood flow such that more blood is delivered to vital organs: heart and brain. In this way, hypoxia can lead to IVH by increasing cerebral blood flow through fragile blood vessels in the periventricular region of the brain.
Any perinatal or neonatal event that results in hypoxia or alters cerebral blood flow increases the risk of IVH.
Why are preterm infants at risk for developing IVH?
Preterm infants are at risk for developing IVH for the following reasons:
They have limited abilities to autoregulate cerebral blood pressure. Therefore, increases in systemic blood pressure result in higher cerebral blood pressures.
They are at risk for hypoxia. Hypoxia, initially, causes increased blood flow to the brain (and heart).
Their blood vessels are thin walled and fragile. They rupture easily if either pressure and/or volume increase.
The periventricular (subependymal) region of the brain is growing and developing at a rapid pace and is well supplied with blood vessels. This is, therefore, the most vulnerable area for hemorrhage.
They are frequently stressed by painful, invasive, or uncomfortable procedures. Stress can lead to both hypoxia and elevated blood pressure.
They frequently need hypertonic IV solutions and medications. These can rapidly expand the intravascular space, leading to increased intracranial blood volume and pressure.