RT Creed: HFNC Has to Prevent Lung Collapse... Right?

From the Desk of the RT: When Surgeons Play Physicist

Published in the Real RT News

Well, sometimes we get interesting orders. Today we got one for a High-Flow Nasal Cannula by a surgeon to prevent a lung from collapsing when the patient has a hemothorax. Apparently, there's a belief that you can just blow some warm, humidified air up a patient's nose and somehow magically vacuum or push blood out of the pleural space like you're clearing a clogged sink.

It’s always an adventure when a surgeon channels their inner physicist and forgets basic anatomy. A hemothorax is blood sitting outside the lung in the chest cavity, crushing the parenchyma from the outside. Pumping flow through a nasal cannula isn't going to evacuate fluid, fix the pressure gradient, or act like some sort of magical structural pillar holding the lung open. If a lung is getting squashed by a pool of blood, it needs to be drained—not treated with a piece of plastic tubing delivering liters of room air.

Sure, high-flow can wash out dead space and help with oxygenation while you actually wait for someone to fix the underlying problem, but pretending it prevents a collapse from a hemothorax is a stretch. If we started blowing enough positive pressure down someone's nose to push back against fluid filling up their chest cavity, you'd run into major pressure issues before you ever solved the bleed. At the end of the day, keep trusting your clinical training—because sometimes you just have to chuckle at the orders and let science do the talking.

Page 677: The Hemothorax-High-Flow Pneumatic Shunt Method

(An Excerpt from the Real Physicians Medical Manual in Response to RT Insubordination)

Today I would like to present a brilliant surgical theory as to how we can prevent a lung from collapsing when a patient presents with a hemothorax, specifically in direct rebuttal to local respiratory therapists whining about basic physics. Many times an RT will look at you with utter confusion when you place an order for a High-Flow Nasal Cannula to manage a chest full of blood. You know what I mean? The chest tube is sitting right there, but you decide to bypass it with sheer aerodynamic genius.

RTs will cringe at this because they can't seem to grasp the deeper physics of the upper airway. Shallow minds they have, you might say. Your RT will whine, "The blood is outside the lung! Pumping humidified air up the nose isn't going to evacuate fluid or fix the pressure gradient!"

Once again, ignore their silly rants. You may even add a note on the chart that says something like, "Trust the flow, ignore the blood!" That usually sets the RT in his place. Anyway, I digress.

Surely we doctors think too much and RTs not enough, that's my point. RTs need to stop thinking and just do what they're told, because this technique explains why we prescribe high-flow for a completely external pleural space issue.

It has to do with pneumatic mass-displacement. Think of it like clearing a clogged sink by blowing air through the faucet. By delivering high liters per minute through a nasal cannula, we generate a powerful positive-pressure force that travels all the way down the trachea, punches through the visceral pleura, and magically pushes the pooled blood right back out of the chest cavity.

Get the idea? If you have a hemothorax compressing the lung from the outside, you just turn up the high-flow to act as an internal structural pillar holding the lung open. It doesn't matter that the fluid is in the pleural space and not the alveoli. Surely RTs will cringe at this idea, but who cares what RTs think anyway.