November 27, 2017

Tiny Medicine – Caring for Our Tiniest Patients in the NICU

By Chris DeRienzo, MD

“Don’t give up! I believe in you all. A person’s a person, no matter how small!” – Horton, from Horton Hears a Who by Dr. Seuss

When I tell people I’m a neonatologist, they usually nod and smile in the way people do when they have absolutely no idea what you’re talking about.  I’ve learned to follow this up with “you know, a doctor who works in the NICU and takes care of really small and really sick newborn babies.” And while most people then identify with a niece, cousin or friend whose baby was born a few weeks early and spent a couple days in the NICU, they truly have no concept of just how small NICU babies can be.

If you really want to grasp “NICU small” – and you’re not up for volunteering in your local NICU as a cuddler – you’re going to need some props. So put down your laptop, phone or iPad, go to the kitchen, and get a gallon of milk, a soda can, a straw, a spoon and a grape.

Start by picking up the gallon of milk.

A full gallon of milk weighs around 8½ pounds, varying just a shade whether you prefer slightly heavier whole milk or slightly lighter skim. Close your eyes and really feel the weight, imagining a baby born right at her due date crying in your arms. While an average newborn weighs a little less than the milk (closer to seven pounds or so), two of my three kids weighed more than the gallon you’re holding, so this is a close enough approximation for our purposes.

Now transfer the gallon of milk to one hand and pick up the soda can with the other.

In America, most soda cans contain 12 ounces of your favorite carbonated beverage, which (including the mass of the aluminum can itself) weighs about the same as the smallest babies I’ve cared for in the NICU. Twelve ounces – or a little under 400 grams – is less than an adult’s weight fluctuates over the course of a few hours, yet was enough to contain the entirety of the smallest people I’ve ever met.

Imagine the contrast as you walk down a hallway in the NICU, passing the soda-can-sized baby sandwiched between two giants, each over 12 times her size. Caring for babies like her requires really, really, really tiny medicine.

Now put down the drinks and pick up the straw.

While straws vary somewhat in size depending on the manufacturer, most grocery store drinking straws have an interior diameter of about 6 millimeters. I want you to pick up the straw and look through its hole – hold it close (but not too close) to your eye, and really try to appreciate how hard it would be to breathe through such a tiny passageway.

The smallest and most premature babies almost invariably need a breathing tube and specialized high-frequency ventilators to help support their immature lungs. The breathing tubes we use to intubate their windpipes have an interior diameter of only 2.5 millimeters. You could easily fit one inside the hole you’re looking through right now… with room to spare.

Now put down the straw and pick up the spoon.

Like straws, spoons also vary in size but a standard teaspoon can hold about 1/6 of an ounce or 5 milliliters of liquid. When the smallest NICU babies need a blood transfusion, we give them about 10 milliliters of packed red blood cells per kilogram of body weight.

Open your soda can and very carefully fill up the spoon. You may need to drip it in.

That liquid you’re now holding inside the teaspoon is more than the amount of blood a 400 gram baby receives in each transfusion. And because we transfuse blood extremely slowly in extremely premature infants, that teaspoon takes nearly four hours to complete its trip into the baby’s bloodstream.

Presuming you’re an average sized adult human, you probably have around a thousand teaspoons of blood flowing through your bloodstream right now.

A 400 gram baby has less than seven.

Finally, put down the spoon (don’t spill the soda!), place your right hand on your heart, pick up the grape with your left hand and carefully make a fist, closing the grape within your left palm.

An adult human heart is about the size of its owner’s fist and beats an average of 70 times per minute. Look at your fist and imagine your own heart beating, feeling its rhythmic thump against your right hand.

Now open your left hand.

The heart of a 400 gram baby is smaller than most grapes and beats on average well over 160 times per minute.

This is why it takes so many adult hearts to care for just one NICU baby.

And these extraordinarily small humans touch nearly every grown-up heart in the NICU during their many, many, many months-long stays.

So the next time you’re in the kitchen fixing yourself a sandwich, some grapes and a soda with a straw in the can, think about the 15 million premature infants born worldwide each year. Think about how impossibly small they really are and the impossibly long odds so many of them face to survive. Think about their families, spending hour after hour next to their isolettes, celebrating each day and worrying each night. And think about the doctors, nurses, nurse practitioners, respiratory therapists, pharmacists, aides, clerks and countless other team members who spend their entire professional lives in service of these tiny children and their parents.

I promise you will never look at your lunch the same way again.

Chris DeRienzo, MD, is board certified in general pediatrics and neonatology. He currently serves as Chief Quality Officer for Mission Health.

To learn more about the services at Mission Children’s Hospital, visit