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 awkward way people do when they have absolutely no idea what you’re talking about. I’ve learned to follow this up with “you know, the kind of a doctor who takes care of really small and really sick NICU babies.” Most people’s eyes then immediately brighten as they identify with a niece, cousin, or friend whose baby had to stay in the NICU for a couple of days. Then they invariably talk about how amazing the nurses were and how small the other NICU babies were in nearby isolettes.
Premature infants are small. Very small. They’re so small that our normal physical understanding of the world just doesn’t make sense. Calling them “small” is like describing a galaxy as “big” or the sun as “heavy.” Words simply cannot do the real thing justice.
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. I recommend that you put down this book, go to your kitchen, and get a gallon of milk, a soda can, a straw, a spoon, and a grape.
Start by picking up the milk. A full gallon of milk weighs plus or minus 8½ pounds, varying just a flicker whether you prefer slightly heavier whole milk or the slightly lighter skim variety. Close your eyes and really feel the weight, imagining a newborn crying in your arms while you gently rock her back and forth. An average newborn actually weighs just a little less than the gallon of milk (closer to 7 pounds), but two of my three kids weighed more than the gallon you’re holding, so it’s 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 sugary beverage, which (including the mass of the aluminum can itself) weighs about the same as the smallest NICU babies I’ve cared for as a doctor. An adult’s weight fluctuates more than 12 ounces—or just under 400 grams—over the course of just a few hours. Yet 400 grams is more than enough to contain the sum total of the smallest person I’ve ever met. You’ll get to meet her in Chapter 7.
Imagine the contrast as you walk down a hallway in the NICU, passing the soda-can-sized baby hunkered down in her isolette (also called an incubator), sandwiched between two giant infants of diabetic mothers, each over 12 times her size. To put this massive size discrepancy in perspective, if I was next to another human being 12 times as big as me, he would stand 72 feet tall or about the length of an average blue whale. He would also weigh nearly a ton and his palm could fit me, my wife, and my three kids all lying together in a line head-to-foot while still being able to close his fingers in a fist. It shouldn’t then be a surprise that caring for babies 12 times smaller than other newborns requires really, really tiny medicine.
Now put down the drinks and pick up the straw. Most grocery store drinking straws have an interior diameter of about 6 millimeters, or just a quarter of an inch. (Yes, I actually measured a sample of straws for the sole purpose of this comparison.) I want you to pick up the straw and look through its hole—hold it really close to your eye, and try to really appreciate how hard it would be to breathe through such a tiny passageway. Despite incredible advances in care over the past century, the smallest and most premature babies invariably need a breathing tube and specialized high-frequency ventilators for some period of time to support their immature lungs. The breathing tubes that doctors and other providers use in the NICU to intubate their windpipes have an interior diameter of only 2.5 millimeters. You could easily fit two of them inside the straw you’re looking through with room to spare.
Learning to intubate babies this small was one of the most harrowing experiences I’ve had as a doctor. For obvious reasons, only the most seasoned providers are called upon to place such a tiny breathing tube in such a tiny baby, usually only seconds after the infant is born and only moments after cutting the umbilical cord. I first learned how to intubate on larger babies during residency under very controlled circumstances and with exceptionally close supervision. It wasn’t until my NICU fellowship that I was given an opportunity to intubate a preemie.
Imagine holding a tube half the size of the straw in your right hand while using a glorified spoon with a flashlight on its tip to open a baby’s mouth and peer inside. You’re looking for a structure no bigger than the tube you’re holding—the vocal cords, which look like thin white strips of dental floss standing out against the back of the baby’s flesh-colored throat. To slide the tube through the cords you have to time it just right, catching the baby just as she’s breathing and not trying to cry, while doing your level best not to push too hard or accidently bounce off the vocal cords and dip into the esophagus (the food pipe) that lives right below the trachea (the windpipe).
Providers are downright religious about how they prepare breathing tubes and the stylets placed inside of them to give the flexible tubes a temporarily more rigid shape. Some believe that a perfectly straight breathing tube is best, while others curve the stylet to give the breathing tube a shape reminiscent of a crescent moon. Personally, I’ve always been a fan of the “hockey stick” bend, which looks exactly like it sounds with a gentle curve at the top followed by a sharp bend up toward the tip that looks like you could use it to whack a microscopic puck. Since most of the tiny babies’ vocal cords I’ve found are toward the front of their throats, using the hockey stick bend allowed me to gently rotate the tube into place along the side of a baby’s mouth while maintaining the ability to still see where it’s going in a space no bigger than a marble.
Should you succeed in passing the tube gently through the cords, you then have toƒ pinch the tube with your right hand, drop the laryngoscope blade from your left, very carefully pull out the stylet, and connect the tube to the respirator without moving it more than a millimeter. Should you inadvertently move it 2 millimeters, the tube might slip out of the windpipe and either drop into the esophagus or fall into the back of the baby’s throat, meaning you have to start the process all over again. Oh, and you have exactly 30 seconds to complete the entire process from start to finish or risk the baby dropping her heart rate or her oxygen saturation levels. It’s a high-wire act for even the most experienced intubators, especially on the tiniest of tiny babies.
Now put down the straw and pick up the spoon. Like straws, spoons vary greatly in size but a standard teaspoon can hold about 5 milliliters of liquid. Open your soda can and very carefully fill up the spoon. You may actually need to use the straw to very slowly drip it in.
When the smallest NICU babies need a blood transfusion, we give them about 10 milliliters (or 2 teaspoons) of packed red blood cells for every kilogram of their body weight. That tiny sip of soda you’re holding in the teaspoon—barely enough of a taste to hazard a guess on the brand of carbonated sweetness that’s in the can—is more than the amount of blood a 400-gram baby receives in each blood transfusion. And because we transfuse blood extremely slowly to protect extremely premature infants from a host of potential problems that could come from transfusing it too fast, that single teaspoon takes nearly four hours to complete its trip into the baby’s bloodstream. At a speed of give or take 1 milliliter an hour, the blood is at such a high risk of clotting during the transfusion that we routinely need to place an extra intravenous line somewhere in a preemie’s body to avoid losing her main intravenous lifeline for medications, hydration, and nutrition.
Presuming you’re an average-sized human adult, you probably have around a thousand teaspoons of blood flowing through your heart, lungs, and bloodstream right now. A 400-gram baby has approximately 7, meaning the now minimally emptier soda can you’re holding still has enough liquid to replace the baby’s entire blood volume 10 times over with almost an ounce to spare. Preemies this small often need many transfusions over the course of their NICU stay, both to make up for the blood we have to draw to test their labs and to support their bone marrow, which doesn’t pick up its own pace of red blood cell production for several weeks after birth. Each time you donate blood, the single unit you give (once fully processed) yields about 300 milliliters of packed red blood cells, enough to fully replace more than eight 400-gram babies’ entire blood volumes or give 75 of them one transfusion.
Finally, put down the spoon and place your right hand on your heart. With your left hand, pick up the grape and carefully make a fist, closing the grape gently within your left palm. An average adult human’s heart is about the size of its owner’s fist and beats 70 times per minute. Look down at your left hand and imagine your own heart beating, feeling its rhythmic thump inside your chest against your right hand.
Now open your left hand. The heart of a 400-gram baby is smaller than your grape, yet contains exactly the same atria, ventricles, valves, and vessels and works in almost exactly the same way as the heart you feel now pounding against your right hand. What’s more, despite its incomprehensibly small size, a preemie’s heart 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 month-long stays.
Even with a good set of props, NICU small is something you truly cannot appreciate until you see it, feel it, and live it in person. I truly had absolutely no appreciation for what NICU small meant before I went to medical school. I thought I did—my younger brother was born around four weeks premature, and at under 5 pounds he seemed tiny when my parents finally brought him home from the hospital a few days after my mom was discharged. He had some yellowing of his skin, known as jaundice, and we kept his bassinet by the picture window in the front of our suburban New York home. For years I was afraid that even the slightest bump would break him into pieces.
That changed when I went to medical school. As a second-year medical student, I remember briefly setting foot in the NICU while on my pediatric surgery rotation. Everything about the place seemed intimidating. First of all, unlike other hospital units, every doctor was stopped at the front door by someone who forced you to remove your white coat, put on a hospital gown, and wash your hands up to your elbows for a full minute. Even the Chairman of the Pediatrics Department didn’t get a pass—anyone who didn’t spend 100% of their time in the NICU wasn’t considered “clean” enough to get past the formidable head unit clerk without a thorough decontamination.
On this particular occasion, after our mandatory disinfection, my team of other medical students and surgical residents throttled through the NICU in typical surgeon fashion. We passed row upon row of isolettes, seeking the relatively large baby in whom we’d placed a gastrostomy tube—a specialized feeding tube that allows the team to pump nutrition directly into a baby’s stomach—the day before. We finally found the baby, the most senior surgical resident examined his new G-tube, and upon finding everything to be healing satisfactorily we hightailed it out of there as fast as possible.
The NICU is simultaneously an intentionally intimidating place to outsiders and an incredibly welcoming place for those who enter its folds as family. I’d experienced the former—born out of an overwhelmingly parental need to protect the smallest, sickest, most vulnerable patients in the hospital—as a medical student. I’d learn the power of the latter soon enough.
My wife was pregnant with our first child when I started residency. I worked an enormous number of hours over the first six months of residency, covering different inpatient services, outpatient clinics, oncology, the general pediatrics wards, and cardiology. But thankfully I didn’t reach the NICU until well after my wife gave birth in late December. I don’t know how we would have made it through her first pregnancy knowing just enough about preemies to be dangerous but not enough to really understand prematurity after being exposed to how terribly things could go wrong during pregnancy without any warning. While that reality made it easy for me to practice medicine with a seemingly endless well of compassion for both mothers and babies, it would fundamentally change my appreciation for how lucky we were that everything went well for us. Fortunately, Reese was born healthy, on time, and didn’t have to visit the NICU, and we had a month of an easy elective rotation to get to know our first baby.
Somewhat ironically, my first real rotation back on service the month after Reese was born was the well-baby nursery. I spent four weeks partnered with another intern and a general pediatrician seeing 25-30 healthy newborns a day, churning through reams of paperwork, and learning very little. Sometimes we’d need to bring babies who were breathing fast or having a hard time feeding into the nursery to monitor them, and a few times I had to call the NICU fellow to come take a look at a baby who wasn’t turning the corner. I was incredibly intrigued with what happened once a NICU fellow decided the baby needed to go across the hallway, through the double doors and into the NICU’s all-encompassing embrace. As luck would have it, my next rotation would finally bring me into the NICU on service, so I was about to find out…
Dr. Chris DeRienzo is a physician leader from North Carolina and author of the book Tiny Medicine – One Doctor’s Biggest Lessons from His Smallest Patients. All views expressed here are his alone and are not attributable to any entity with which he may be affiliated. Follow him on Twitter at @ChrisDeRienzoMD and on LinkedIn.