How Cardiac Conduction is Like a Toilet

Frequently, we encounter babies in the NICU with sudden wonkiness on the cardiac monitor. At first glance, many of these "funny looking beats" appear to be PVC's, but much more commonly they represent artifact: hiccups, preemie myoclonic jerks, or other abnormal body movements. Since things like hiccups can be signs of overstimulation in the preemie, it's nice if we can differentiate a hiccup from a PVC without lifting an isolette cover to peek inside.

The good news is that often we can make this distinction by carefully examining the rhythm, if we have an understanding of the relative and absolute refractory periods. To best understand this stuff, first think about flushing a toilet. Right after the flush, what happens if you try to press the handle again? Nothing, right? The toilet is absolutely refractory to another flush since it has just been "depolarized." After a few seconds, though, if I depress the handle again, the toilet is only relatively refractory to another flush, and we get an abnormal, weak and funny-sounding "depolarization." Let's translate that to the heart.

The absolute refractory period stretches from the QRS complex to the first half of the T wave. No abnormal beats will be conducted during this interval. If I see a QRS and then another "beat" immediately after that QRS, I know that the second "beat" could not possibly be a cardiac depolarization. It's most likely a hiccup.

From the apex of the T wave to the end of the T wave, you have the relative refractory period. Remember our abnormal flush? Same thing in the heart, only with worse consequences. The abnormal depolarizations during this vulnerable period can lead to lethal arrhythmias. Look up the R-on-T phenomenon for an example of the badness that can ensue when an ectopic beat lands on the previous T wave.

Finally, following the T wave, there is a non-refractory period. This is where abnormal electrical foci most commonly cause PVC's. In this area, PVC's are usually not dangerous unless they are very frequent.

A Google Images search for "EKG refractory period" will turn up some neat diagrams that depict these periods and the corresponding parts of the EKG complex. And where did I get this crazy toilet analogy? I got it from an old medic, who had learned it from an even older medic. Based solely on its weirdness, I suspect that it did originate within EMS circles long ago.

What They Mean

Good to be back after a long break! I rarely steal post ideas this blatantly, but this is a variation on the theme posted by At Your Cervix a couple of weeks ago. Here are some things that we say to our coworkers, followed by the thoughts in our heads that we know to be true.

Pediatric resident says: "Hmm - good question. Hey... Can I call you back in ten minutes?"
What They Mean (WTM): "I have no earthly idea, but I'm 'bout to get my Google on."

Pharmacist says: "You didn't get those fluids? Weird! I tubed them an hour ago!"
WTM: "Prepared the fluids an hour ago and just found them on the counter. Tubing them now."

NICU nurse says: "Yes, I repeated the patient's temp, but heck, wouldn't hurt to do it again."
WTM: "I totally %#$&#^ forgot about that temperature. I'm sure gonna look dumb if it's 94!"

NICU nurse #2 says: "Dude, you should have gone to medical school."
WTM: "How can you know pharmacology, yet your babies' diapers slide right off their butts?"

Neonatologist says: "Good job, nurse. Another life saved!"
WTM: "In spite of everything you've been doing, this kiddo has inexplicably survived."

Respiratory therapist says: *loud slurping, gurgling noises* Hey, check this out!"
WTM: "Do not look at the orange, chunky, potentially pulsatile blob in this sputum trap."

E.J. says: "I love everything about my coworkers, even the crazy things you say to me."
WIM: "Okay, except for pharmacy. The 'slow tube system' thing again? Really?"

NICU Handshakes: Gracious or Grubby?

After a baby is admitted to our neonatal intensive care unit, nurses have several goals in our initial talks with the infant's visitors. Two big ones always come to mind for me right away: to instill a sense of confidence among family members and to help keep the baby free from infection. For a long time, I failed to connect the two issues, but I've learned that they do intersect at a curious place: the handshake.

I'm a handshaker. Chalk it up to a conservative, old school upbringing. I try to shake hands with every father I meet in our unit. I think that dads are frequently ignored in the NICU, and I think a handshake is a good start to making a professional impression and to making fathers feel valued. Every once in a while, however, my handshake does not have the intended effect. Recently I extended my hand to a father and he looked at me like I was an outright whackadoo, saying that he had just sanitized with Purell.

This set me out on a quest for more information about provider-patient interactions, infection and expectations. Here's what I found. Apparently, around 80% of patients like handshakes from their physicians. A handshake with a mom can even be a neonatal diagnostic tool. Just be careful not to get hurt! However, my PubMed search turned up no data on the infection control ramifications in any setting, nothing about handshakes by nurses and nothing on the social expectations of NICU families in particular.

What do you think? If I wash my hands at the beginning of the shift and I use hand sanitizer before every baby contact and after every baby contact, is it okay to continue with my handshakes? For my part, in the absence of some data, I'm forging ahead... even if it gets me the occasional odd look.

Gratitude

I've been away for a couple of weeks on a trip where I met nurses from all corners of the globe. When I set off for another country a full day away from the US, I knew this would not be an ordinary NICU nursing conference. And as promised, I did learn a lot about modifications of neonatal care in low-resource areas. But more than that, my entire perspective on neo nursing has changed.

If you're a nurse in an area that has the computer access to read this blog, consider yourself fortunate. You're ahead of thousands of nurses, many of whom would really just be content with an uncontaminated water supply. Before you complain about your next assignment, think about the incredible people I met who decribed the following situations.

What if you worked in a hospital so overcrowded that you weaned preemies to open crib at a kilogram even? What if, at that same place, you were expected to utilize forced cup feeding to meet a goal of discharge between 1400 and 1500 grams?

What if your neonatologist was a "general physician and surgeon" who primarily treated and operated on adults? What if, on the same unit, 28 weeks was the limit of viability?

What if you went to work every day with the knowledge of a 46% mortality rate hanging over your head... and while that was hard, it was the infant abandonment issue that really killed the morale?

What if your unit director had never even heard of a cord blood gas?

What if you remember seeing an Ambu bag in nursing school, but you hadn't come across one in five years because your current facility didn't even have an oxygen source?

What if you worked in a huge ward of 60-70 babies, both sick and well, and you were the only nurse supported by a few unlicensed assistants?

What if you were a bedside nurse who was told that insertion of a peripheral IV was a physician function, because as a nurse you risk "damaging the patient's organs?"

In the global picture, we have it made here in the states. I don't know about you, but at least for this month of thanksgiving, I'm resolving not to complain.