Today’s learning topic is Failure to Thrive in an infant. This is a baby that won’t put on weight, despite assurances that the baby is taking in adequate formula.
The most important thing to determ ine is whether the parents are mixing formula properly. A “Cost saving” measure (because formula is expensive) is parents will occasionally mix in more water with the formula. This leads to the infant taking in enough volume, but nowhere near the correct amount of calories. This leads to poor weight gain or weight loss, and can even cause severe low sodium and brain swelling. It can kill the child if unrecognized for long enough. The ratio is ALWAYS 1 scoop formula, 2 scoops water. Doesn’t matter what kind of formula you use.
So you’ve determined that the parents are mixing the formula properly, but the child is still losing weight…what now?
The most important two things to evaluate are whether or not the child has a heart function problem, or has a genetic disorder. The two most important genetic disorders are Cystic Fibrosis, and Prader-Willi syndrome.
With congenital heart failure, usually caused by a valvular malformation or defect in the wall of the heart (septal defect), the infant’s body will do what’s called “third-space” fluid. This will cause fluid from the blood vessels to weep out into surrounding tissues where gravity allows it to collect, or in areas where blood capillaries are particularly permeable. The area that usually gets hit the hardest in infants is the lungs. Since they’re new, they don’t have much water in their bodies, but they also are very sensitive to changes. They might not be gasping for air, turning blue around the mouth, or coughing up frothy fluid from their lungs, but they may look like they’re “pulling” for air, and their rib muscles will retract, and they won’t gain weight. Why?
They won’t gain weight because of increased metabolic demand; the body is putting so much effort and energy into trying to get enough oxygen, they are burning up all available calories and thensome. This is also true of babies with cystic fibrosis; their mucus is too thick to mobilize properly, and they have to work harder to breathe. They also may have issues with producing the proper enzymes for digestion, due to the pancreas also being affected by the disorder.
Now, Prader-Willi kids can trick you. The common idea of a prader-willi child is obese with compulsion to eat, developmentally delayed both mentally and physically. However, Prader-willi babies will usually be small and suffer from failure to thrive. This is due to hypotonia (muscle weakness) and poor coordination of the sucking reflex. If you’re studying for a medical board exam, especially pediatrics or family medicine, that is definitely a pearl to remember.
So what do you do to fix the patient?
In these cases, the most sensible thing to do is to increase the calories available, and treat the underlying cause. This is easier to do with congenital heart disease; you either fix the leak, repair/replace the valve, or replace the heart. In the meantime, you can use low, weight dosed medications such as diuretics, ACE inhibitors, and others to help medically treat the heart failure.
With Cystic fibrosis kids, the number one most important thing is to help break up the large amount of thick mucus in the lungs. Highly concentrated salt water that is nebulized for inhalation (hypertonic saline neb) is the goto treatment of choice for CF patients, along with chest physiotherapy. Evaluation by a pediatric dietician is a must. A dietician can help determine just how many calories a CF baby needs, and enzymes can be supplemented if needed.
Finally in those who suffer from Prader-Willi syndrome, speech and occupational therapy can be utilized to increase muscle coordination and strength to provide a better suckle, and nasogastric tubes can be utilized for feedings until that is accomplished. Again, evaluation by a pediatric dietitian will be helpful.
Keep in mind, there are many other causes of failure to thrive. This is just some of the highlights, and specific things that I learned today.
So, that’s what I learned today! I hope this helped you learn something too.