TILIF #18: Uncontrolled

When I had cancer, I shaved my head. Hair was slowly falling out and it would have taken care of itself, but I bought into an idea that I learned from the lovely people at the local cancer center. That disease takes away many things - energy, appetite, future plans - but they all really boil down to a loss of control. You can't control when you go places, what you can eat, activities you're able to participate in, or whether the treatments will work. Taking back that little bit of control from the disease, even for something as superficial as choosing when my hair would go, felt freeing.

The other night, I was taking care of a very sick patient*. Even for the ICU, he was very, very sick and has been for quite some time. Pick an organ and chances are it's failing. There are all manner of tubes and wires coming from every part of his body. Part of what makes this so hard is that he was a totally normal child until a couple years ago, so "back to normal" is the unstated and possibly unreachable goal.

His family has done everything they could, even donating bone marrow for us to transplant. But everytime it feels like we're about to make progress, there's another setback, rare side effect or complication. This night, there were several things that went wrong; each could have been life threatening, but we were able to at least start addressing each of them by early morning.

Normally, this patient's mom is at the bedside, but when she needs to leave the hospital, grandma takes over. Grandma is fierce. She is a wonderful advocate for her grandchild, and doesn't stop pushing the team until she's satisfied. The issue that was most bothering the patient, and thus grandma, was his being itchy. Compared to failing lungs, kidneys, liver, immune system, etc., itchiness was admittedly not my highest priority, but it was grandma's. She was fixated on it, and after a while it admittedly became frustrating for everyone. This kid was old enough to understand that we needed him to stop itching, but he just wouldn't - to the point where he was bleeding. This only further upset grandma. Why couldn't we get something a simple as itching under control.

Grandma took a break and went to get food at around 3am. When she returned about an hour later, I sat down with her in the corner of the room and did my best to explain all the complicated interventions we were doing to stabilize the patient, also what we were trying to do about the itching. She listened politely and I braced for another lament about the persistent itchiness when she quietly asked, "Is he going to make it through this?"

I was blindsided. 21 hours into my shift, I stumbled through a non-committal answer to the effect of: "We're doing everything we can and we're going to take it one step at a time." We talked for a bit, but it was then that I realized that the itching was a symptom in more ways than one. It was one of the last things that the patient could still control and one of the few seemingly fixable things that grandma could fight for to help her grandson. 

TILIF: "Volcano penis" is the slightly more colloquial name for congenital megaprepuce, which is a fairly self-explanatory anatomical variation involving extensively redundant foreskin. 

Also, the oculocardiac reflex is yet another example of the unintelligent design of the human body. Basically, the nerves that innervate many parts of the eye send signals back to the brainstem through the ophthalmic division of the trigeminal nerve (cranial nerve V). The area in the brainstem that processes this information is really close to the processing area of the vagus nerve (cranial nerve X). The upshot of which is if you do surgery on the eye (or land a really unfortunate punch to the face), the signals can get crossed in the brain and your heart can suddenly slow down to the point that it can't support the body's needs, or worse, go into an arrhythmia and stop.

Finally, a quick way to see that a patient with an oxygen mask on is breathing is to look at the fogging pattern:

• No fogging: not exhaling humid air, thus not breathing
• Fogging but no defogging: exhaling humid air but not getting any dry oxygen to flush it out, so breathing but you should check the oxygen tubing/tank
• Fogging and defogging rhythmically: good to go!

*As usual, patient details have been changed to protect their privacy

TILIF #17: Forecasting an airway, ECMO hope, and lot's o' math

On an endotracheal tube (breathing tube for intubated patients) there is often an inflatable ring called a cuff that can be filled with air to help make a better seal in a patient's airway. Since you can't easily see the cuff to check how inflated it is, there is a little air-bladder at the other end of the tiny tube used to inflate it. Since the two soft bubbles of plastic are connected by the rigid little tube, they feel the same pressure. This means if you squeeze on the little balloon outside the body, you get instant intuitive feedback about the balloon inside the body. After intubating, you can also use this relationship to feel where the internal balloon is by placing your hand on the neck while squeezing the outer bubble and feeling the bounce of the inner balloon pressing out through the soft tissue of the neck. Nifty!

I never gave a second thought to what the little balloon would be called. Cuff pressure bladder, maybe? The anesthesiologist I worked with today scraped the bottom of the esoteric knowledge barrel by informing me that it is actually called a "pilot balloon." But that made me wonder: why?! What a weird term. The anesthesiologist hypothesized that it was like a pilot light for a furnace, because the little fire is indicative of the ability to start larger fires inside. I don't buy that.

If you Google "pilot balloon" you'll note that the first non-medical entry you find from meteorology. Pilot-balloon (or "pibal") observation is when you send a balloon up into the atmosphere to measure the direction of upper-level winds. This is shockingly close to a perfect metaphor for our little device - a balloon that measures the ability for air to move through a patient's upper airway. Coincidence?

I also recently learned the amazing story¹ of the first ECMO baby. Extracorporeal membrane oxygenation (ECMO) is basically medium-term heart-lung bypass. It is one of the most extreme, invasive and risky interventions that is done in all of medicine. It was first tried on adults in the '60s but the first study was a disaster with 90% of patients dying. The whole concept may have been scrapped where it not for a hail-mary intervention on the newborn baby of an illegal immigrant in Irvine, CA. The child's mother was told that the child was dying (which she almost certainly was) and, before fleeing the hospital due to immigration status concerns, she consented to allowing the doctors there to try a radical, unproven treatment.

The new technology that allowed this medical advancement was actually the development of silicone tubing, made from basically the same stuff used as a bathroom tile sealant. Unlike other plastics, this substance actually allows gases like oxygen to diffuse into blood flowing by without requiring the blood to be damaged with mixing devices. This baby's lungs were stuck in a high resistance fetal physiology and needed more time to mature. The surgeons placed catheters into the major veins and arteries to divert most of the baby's blood to this oxygenation device outside the body before allowing it back in to feed the tissues. It worked! The baby survived on the device for 6 days, enough time for the pulmonary pressures to lower and the lungs to oxygenate the blood on their own. One of the only complications was that a piece of the silicone tubing broke off while being disconnected, lodging in the little girl's lung.

The mother was never seen again. She had given her child birthright US citizenship and given the doctors permission to try for a miracle, but likely never knew the girl's fate. The baby was named Esperanza, Spanish for "hope," by the nurses and she was raised by loving foster parents. She later met the doctor that saved her life and has become a mild celebrity in the ECMO world.

Lastly, and this is basically just for me, I learned a bunch of hard-core physiology. And, to better understand the relationships between some variables, I did a long-form derivation. Nothing to see here!

  DO2 = oxygen delivery

         = CO x CaO2 x 10

         = (HR x SV) x (1.34 x [Hgb] x SaO2 + 0.003 x PaO2) x 10

         = (HR x SV) x (1.34 x [Hgb] x SaO2) x 10

  VO2 = oxygen consumption

         = CO x (CaO2 - CvO2)  x 10

         = CO x ((1.34 x [Hgb] x SaO2) - (1.34 x [Hgb] x SvO2))  x 10

         = CO x ((1.34 x [Hgb] x SaO2) - (1.34 x [Hgb] x SvO2))  x 13.4

VO2:DO2 =	10 x CO x (CaO2 - CvO2)
	10 x CO x CaO2

=	1.34 x [Hgb] (SaO2  -  SvO2)
	1.34 x [Hgb] SaO2

                    =  SaO2   -   SvO2
                        SaO2       SaO2

                    = 1 - SvO2
                            SaO2

  DO2:VO2 =          1         
                          1 - SvO2
                               SaO2

                 = typically 5:1, but stable down to 2:1

Comparable to mixed venous saturation: 5:1=80%, 2:1=50%, but only when FiO2 is 100%

ECMO is for getting back above 2:1 or limiting damaging interventions used to do so.

1. Bartlett, Robert H. Esperanza: The First Neonatal ECMO Patient, ASAIO Journal: November/December 2017 - Volume 63 - Issue 6 - p 832-843 doi: 10.1097/MAT.0000000000000697

TILIF #16: From behind the ether screen

A surgeon observing a case today asked if it would be okay if he peered over the blood brain barrier. This was a tongue in cheek reference to the cloth drape that separates the sterile surgical field ("blood") from the head ("brain") of the patient, behind which the anesthesiology provider monitors the airway. The double meaning, is that the surgeons our glorified mechanics that deal with blood and the anesthesiologists are "the brains," doing a lot of physics, physiology and pharmacology, to keep the patient alive despite the surgeons best efforts to the contrary.

TILIF that the original name for this dividing drape was the "ether screen." The first widely used anesthetic was ether, a clear volatile liquid that quickly turns to a gas when not in an enclosed bottle. This is also the substance that you see depicted on TV and film by splashing a bottle onto a rag before holding the rag to a unsuspecting victim's face before they promptly fall asleep*.

So, back before we had well-controlled anesthesia techniques and form-fitting plastic facial masks, the ABSOLUTELY BONKERS standard of care was called "open drop" ether anesthesia. The anesthesiologist would simple drip ether slowly from a bottle onto a rag that was placed on the patient's face. As the liquid evaporated, the patient would breath it in and lose feeling/consciousness. You titrated the dose by... dripping it from the bottle faster or slower. But recall that there aren't any masks or tubes involved, which means that this gas is free to spread anywhere, including to the surgeons who may be quite close to the patient's face. To limit the intoxicating effects on the people with the knives, anesthesiologists started putting up a barrier to keep this heavier than air gas from wafting down the body. Interestingly, the anesthesiologists did not have any such protections,

*This would actually be pretty dangerous, as an overdose would cause the patient not just to pass out, but to stop breathing, likely for long enough to cause serious hypoxic injury.

TILIF #15: Testing 1... 2... 3...

Test #1: I'm (hopefully) done with my pediatric boards! As mentioned in my previous post, I took this 9-hour exam in mid-October and will hear back about if I passed at some point in the next several weeks. It was grueling but so was every other major exam I've taken up to this point, so here's hoping I survived. Next up, Pediatric Critical Care Medicine boards in 2024!

Apologies for the absence of blog posts in the past two months. I had planned to take some dedicated time off to study but then some serious family health issues came up that stopped me earlier than expected. I hope all three of my dedicated readers can forgive me.

Test #2: TILIF, towards the end of the major work of a spinal fusion surgery, the patient is briefly allowed to wake up to make sure they can still move all their limbs. This is crazy.

A spinal fusion is typically the last resort for kids with terrible scoliosis, where the spine weaves side to side like a big 'S'. The procedure it truly the goriest surgery I've ever seen.

{WARNING: Gross details ahead}

from Spinal News International at https://spinalnewsinternational.com
/depuy-synthes-receives-us-fda-clearance-for-cement-
augmented-pedicle-screw-systems/

The surgeons place the patient face down and then splay open the back, spreading apart the muscles to expose the spine. They then clip away the ligaments and extra pieces of bone to make space for their hardware. Next, bolts with slots in the heads are drilled into each side of the affected vertebrae. Then comes the hard part; you have to you have to weave the misaligned vertebrae onto the straight steel bar. This take A LOT of force - specifically the amount of force of two grown men putting all their weight onto some wrenches attached to a child's spine.

Right as they are starting on placing the second bar, the anesthesiologist turns off all sedation, with the hope of timing it such that when all the hardware (and bones) are in their final place, that the patient will briefly wake up just long enough to wiggle their finger/toes before being quickly re-sedated and then sewn back up. It is wild that we woke up a child with her spine fully exposed, just to ask her to wiggle her toes.

{End of gross details}

Test #3: The other test to monitor for nerve damage during spinal surgery is the aptly named intraoperative neurophysiological monitoring system whereby you place dozens of electrodes all over the body and monitor for electrical signals being transmitted by both sensory and motor neurons. It's finicky and prone to equipment problems, which is why the crude-but-effective method described above is also performed. The sensory nerves can be monitored continuously but the motor ones can only be tested by making the patient move. So once every 10 minutes or so, the technician asks the surgeons to hold off on cutting/hammering/cranking/etc for a few seconds to send a twitch pulse to all the electrodes and see the response as the patient briefly convulses.

Whenever a patient is brought to the PICU post-operatively, there is a verbal hand-off from the surgery and anesthesia teams to the PICU team. More than once I had received hand-off after one of these big spinal cases and been told what seemed like gibberish about them having "lost SEPs on part of the left leg, but had good movement during the wake-up test." Thanks to sitting in on this case today, I not only got another intubation attempt (which was successful, BTW) but also learned how orthopaedic and neurosurgery folks monitor for nerve damage in surgeries that often land patients in the ICU for a few days.

TILIF #14: Boardom

One of the many strange things about medical education is the seemingly random interval between the various standardized competency exams that you take along the way to becoming a fully licensed, board-certified physician. For example, your medical licensing exams happen in four parts: the first after two years of medical school, the next two after the third year of medical school, and the final test is taken up to a year after you've completed medical school. From there, the next big hurdle is becoming board certified by whichever medical board oversees your residency. Completing this signifies being able to practice independently in your chosen field. But some specialties have a multi-step board exam just like for medical licensing while others just require that you take your boards at some point following completion of your residency training.

The American Board of Pediatrics, for which I have recently become board eligible, gives us seven years post-graduation to take our board exam which is held on every year in mid-October. Generally, everyone aims to take the exam as soon as possible (so three months after graduating from residency), to allow the least time for forgetting the sorts of minute details that are ingrained into you during residency for this exam but that will rarely if ever come up during your day-to-day practicing of either general or specialty pediatrics. For most people, this means dedicating as much as possible of the three months after graduation to studying. If you're going into private practice, you might ask for a delayed start time or a extended vacation to properly prepare. If you're going into fellowship, most programs will allow for a lighter schedule during this time so that you can get this test out of the way and concentrate the remainder of your fellowship time on mastering the more specialized knowledge of that field.

Unfortunately, I have picked one of the very few fields where the luxury of taking it easy for a few months is not entertained. Pediatric critical care programs are easily some of the most clinically heavy fellowships out there. Most other fellowships expect you to spend approximately two of your three years on research projects to better establish yourself in the field and add to the collective knowledge of the discipline. In the pediatric ICU, we spend roughly 18 of our 36 months on service in the ICU, pulling 12-13 hour shifts with the occasional 25-hour in-house call.

In regards to this, I've been given some rather frustrating advice. Somehow I'm supposed to focus as much of my energy as possible on passing boards during these first three months. But I'm also trying to navigate that steep learning curve that comes with being immersed so fully in this completely new level of care. Thankfully there are pretty low expectations for a new fellow in regards to both knowledge and skill, so, if I don't mind playing the fool, I can coast on my current ineptitude until November. The real problem though is that the work that we're trying to do is to take care of very sick children, so giving it any less than your all really doesn't feel great, even if there are many other people to pick up the slack.

Rant over. I know it's not all that bad. I'm pretty sure there's a way to strike a reasonable balance; I just don't like to multitask in that way at work. Hopefully I figure it out soon!

TILIF: Thrombopoietin mimetics, are drugs that mimic the hormones that stimulate the production of platelets.

A "walking taco" is apparently a midwestern state fair and tailgating staple that involves taking a bag of nacho cheese Doritos or Fritos and pouring into it your favorite taco toppings. This makes it easy to carry one-handed, leaving the other hand available for an alcoholic beverage.

Elastance is a totally made-up-sounding word that means the opposite of (or, mathematically, the inverse of) compliance.

Neurally Adjusted Ventilatory Assist (NAVA) is a cool way of signalling a ventilator to give a breath in sync with a patient's natural breathing pattern. It involves placing a sensor down the patient's esophagus and detecting the nervous signals to the diaphragm that would normally trigger a breath. That way you know when an attempted breath is happening sooner than the traditional way of watching for pressure/flow changes through the vent tubing.

TILIF #13: ♬ ♫ ♪ I've got you under my skin ♪ ♫ ♬

Last Monday, I had my first successful solo arterial line placement! Woot!

One of the defining parts of the job description of an intensivist is being comfortable doing minor sterile procedures at the bedside. So, while we are not surgeons, we need to be able to place arterial and central venous lines and do the associated cutting and sewing. Just like with normal surgeries, our patients are usually asleep and family is usually not around, which means, just like with normal surgeries, there is often music playing!

I know this is not what is portrayed on most medical dramas, but most ORs are playing the spotify playlist of the most senior surgeon in the room. I've listened to classic rock, rap, pop, folk, classical, country. And you never know what the whims of any particular surgeon will be on any particular day.

It's a strange sort of status symbol to be the one in the room with a half-dozen people to get  to pick the music. You'll notice if an attending scrubs out of a case and lets the resident finish closing the wound (a tedious and not particularly technically difficult task), that the resident may get to pick the music for the remainder of the time.

Well, our procedures may not be as big of a deal, but we still can play music and this was the first time I had (a) put in a line by myself, and, more importantly, (b) been the one to pick the music. Once all of our sterile gear was opened and the patient was comfortably sedated, the nurse for the room pulled up YouTube on the patient's entertainment screen and asked, "What'll it be, doc?"

I was a bit nervous about the procedure and initially tried to defer to whatever anyone else wanted, but she ignored call-outs from the resident and the other supervising fellow in the room and made clear eye-contact with me indicating that this was as necessary as the safety "time-out" we had just completed. Well, I had been on a big band kick recently and decided that I might as well dive on in. "Frank Sinatra, please!" 

She was initially taken aback but then I got an approving nod. "Haven't heard that one before. I like it!" And just like that we had a Sinatra playlist setting the mood for my (very slow and very cautious) placing of this kid's arterial line. It was actually really nice. I know Frank like the back of my hand, so it was like having a familiar beat to perform to. My favorite part though, was when, after I had already successfully placed the line, and was suturing in place, the song I've Got You Under My Skin came on. "A little on the nose," I said to groans.

TILIF: Pulmonary vascular resistance (PVR) has really weird units. PVR is the resistance that blood must overcome to pass through the pulmonary vasculature. It is defined analogously to Ohm's law for electrical resistance (resistance = voltage/current), except voltage is the pressure gradient through the lungs and the current is the cardiac output. Pressure can be measured in mmHg and the cardiac output is L/min. So, while you could keep the units as a simple mmHg⋅min/L, by swapping things out for slightly dated units of force, you get units of dynes⋅sec/cm⁵, which is, for some reason, the continued standard. At some point people were annoyed with this convoluted and completely unintuitive mess and named an entirely new unit after one of the pioneers in PVR research, Paul Woods. So you will sometimes see PVR listed in WUs, or Wood's Units.

Apparently John Deere is a big deal in Iowa. John Deere, the person, founded his company in the appropriately named middle-of-nowhere town of Grand Detour, IL before moving operations to the Mississippi River in the IL/IA state-line-spanning Quad Cities area. Also, apparently there are several very regionally dominant farming companies that have prominent color associations reminiscent of college sports with the Americana brand-loyalty of mid-century car companies.

To give a patient a granulocyte (a type of white blood cell) transfusion, you need 24-48 hours of lead time. This is because these cells don't keep and have to be very closely matched to the recipient. So you need to find the appropriate donor, give them a medication that causes granulocyte cell overproduction, wait at least a day for it to work, then transport them to your patient.

TILIF #12: Yeah-huh tagbacks!

"Tag-g-g! You're it!" This was not what I was expecting when beckoned into my patient's room. He had been coloring with crayons and waved me into the room as I walked past.

There's an adage in pediatrics that, compared to adults, kids get sick faster. They have a lot of physiologic reserve, so they are fine... they are fine... they are fine... until they are not. Accordingly, if a patient suddenly looks worse on the general pediatric floors, don't ignore it - they may need the ICU and soon. But the corollary is that children often quickly turn the corner toward recovery too.

As kids get sicker and get better they are moved in and out of the intensive care unit. The move to "the unit" is usually pretty quick. We always have a bed or two ready to emergently accept patients and can speedily adapt our nursing distribution to cover the other patients while we stabilize the new kid. Moving to the general floors, however, can be a bit of a waiting game. The stars need to align to have an appropriate room, bed/crib, nurse, and doctor ready at the same time to safely transfer care. And there's less urgency because the child's clinical condition is necessarily stable or improving for them to be leaving the ICU. Worst-case scenario, the child is getting a higher level of care than they need while they wait to transfer.

As I reach to tag my patient back, he squirms away in his hospital bed and stutters, "No tag-g-backs!" I'm a little shocked that he had thought this through so well.

While we grumble about how long it takes to transfer kids out of the unit, sometimes it's nice to have a relatively healthy kid around for a while. After all, everyone in the PICU has trained in general pediatrics first, so we've played games to get our physical exam more painlessly, chatted about Paw Patrol and Frozen ad nauseum, gotten countless high-fives, and waved "bye-bye" leaving each room^*. When most of your patients are either heavily sedated or just too sick to have normal kid interactions, you have to take every opportunity to remind yourself what you're working so hard to restore to your patients: the simple joys of being a kid. 

I snap my fingers and facetiously say, "Drat!" I scan the otherwise empty room for someone else to tag.

"G-go g-get the n-nurse!" he says excitedly.

That morning, the unit had an honor walk. This is the solemn event when all the available staff in the unit line the hallways to bear witness to an organ donor being escorted by their family to the operating room. It is such a hard decision that no parent expects to have to make. To be an eligible donor, the organs must be in pretty good condition, so these are usually children that were healthy and vibrant a few days ago until some tragic circumstance changed everything.

In this horrible moment, we - and by "we" I mean very experienced social workers - ask these parents to consent to sending the body of their recently deceased child, still in the hospital bed on "life-support," to undergo one last surgery to scavenge the usable tissues and ship them out to other nameless patients in desperate need. We try to remain as neutral as possible while presenting the choice, so as not to bias them towards doing something they don't believe in or will regret. But everyone involved is hoping beyond hope that they will say yes. It is so tempting to walk these parents to the opposite hallway in the unit were a patient and their family has been waiting for months for a new organ - their only chance for continued survival.

As I run out of the room and towards the nurses' station, the patient's nurse looks up with mild concern. "What's going on? Do you need something?" she asks.

"I just needed to tell you that..." [I poke her shoulder] "you're it! No tag-backs!"

An honor walk is an emotionally taxing event to participate in. The ICU can usually pause for a moment, but it doesn't stop. Other patients need our help and they can't wait for us to collect ourselves before returning to the job at hand. The ICU is always in motion. There are always new kids coming in and improved ones going out. There are always unstable patients that you need to pass-off to the night team, who will pass them right back to you in the morning, having taken the next steps toward whichever outcome.

But even knowing the emotional toll that participating will take, when you have taken care of a patient that eventually has an honor walk, you kind of want to be there when it happens. You may have been with that family as they arrived, as they were told that their baby wasn't coming back from this, and sometimes (as was the case for me today) you may have been part of the team that did the brain death exam. When those patients head to the OR for the final time, you kinda hope to be stuck holding the hot-potato; you gladly allow yourself to be "it" in the game of Tag.

"What?!" the nurse yells, so that our patient can hear, giggling in his bed. She storms towards the room on faux-outrage, "You got the doctor to tag me?! Well, you're it again! No tag-backs!"

TILIF: The pores of Khon are connections between alveoli (tiny air sacs) in the lungs and appear around the second year of life. A similar structure called the canals of Lambert connect bronchioles (the smallest air tubes of the respiratory tree) to adjacent alveoli. The canals develop around age 6. These two structures allow for the passage of fluid and bacteria, possibly contributing to increased risk of pneumonia, but they also allow for connections between adjacent parts of lungs, which decreases the risk of lung collapse or atelectasis, which is seen more commonly in children than adults.

*Teenagers particularly enjoy when you wave bye-bye