You're in the OR or a hectic ER bay. The patient needs an airway, and they need it five minutes ago. You grab an endotracheal tube, check the cuff, and slide it past the vocal cords. Most clinicians don't even look for it anymore, but that tiny, oval-shaped hole near the tip—the Murphy eye endotracheal tube feature—is basically the only thing standing between a routine procedure and a catastrophic hypoxic event if things go sideways. It’s one of those "hidden in plain sight" design wins that hasn’t changed much in decades because, frankly, it works.
If you’ve ever wondered why some tubes have that side hole and others don't, you're tapping into a debate that goes back to the mid-20th century. Named after Dr. Francis J. Murphy, an anesthesiologist who realized that a single opening at the end of a tube was a massive point of failure, this design is now the global default. But it isn't perfect.
The mechanics of the Murphy eye endotracheal tube
Think of a standard tube as a straw. If you put the tip of that straw against the bottom of a cup, you can’t suck up any liquid. In the human trachea, the "bottom of the cup" is usually a wall of thick mucus or the tracheal wall itself. If the distal tip (the Bevel) gets clogged or pressed against the tissue, the patient stops getting oxygen.
That's where the Murphy eye comes in.
It acts as a vent. By having a secondary portal for gas exchange, the Murphy eye endotracheal tube ensures that even if the primary opening is obstructed, air can still bypass the blockage. It’s a redundancy system. Simple. Elegant. Life-saving.
Most modern tubes are made of polyvinyl chloride (PVC), which is firm enough to navigate the anatomy but softens at body temperature. When you look at a Murphy tube, you'll notice the eye is positioned opposite the bevel. This isn't accidental. It’s designed to maximize the chance that at least one opening remains patent.
Why the Magill tube lost the popularity contest
Before Murphy’s design became the king of the hill, we had the Magill tube. It’s basically the same thing but without the hole. Some old-school providers still swear by them because they are "atraumatic." Without that extra hole cut into the side, the tube is smoother. There are fewer edges to snag on delicate vocal cords or nasal passages during a blind intubation.
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But honestly? The risk of a "tipped" tube—where the end of the tube sucks against the side of the trachea like a vacuum attachment—is just too high for most modern practices. While a Magill tube might be slightly easier to pass in a narrow airway, the Murphy eye endotracheal tube provides a safety margin that most anesthesiologists aren't willing to trade away.
The hidden risks no one mentions
Nothing in medicine is free. The Murphy eye provides safety, but it introduces its own set of headaches.
First, let's talk about the "snag factor." Because there is a hole in the side of the tube, the tip of a stylet or a suction catheter can occasionally get caught in the eye during a procedure. If you’re trying to pass a fiberoptic scope through a Murphy eye endotracheal tube, you might find the scope poking out the side hole instead of the main tip. It's annoying at best and dangerous at worst if it causes a delay in a difficult airway scenario.
Then there’s the trauma issue. Cutting that hole into the PVC creates edges. Even though manufacturers try to smooth them down, the Murphy eye can technically harbor secretions or cause slightly more irritation to the tracheal mucosa than a smooth Magill tip.
Does the eye actually prevent obstruction?
Surprisingly, the data is a bit mixed, or at least nuanced. A classic study often cited in airway management circles suggests that while the Murphy eye is great for preventing total obstruction from the tracheal wall, it’s less effective against thick, tenacious mucus plugs. If a plug is big enough to block the 7.5mm distal tip, it’s probably big enough to gum up the eye, too.
However, in the context of "beveled tip occlusion"—where the angle of the tube's tip meets the tracheal wall—the Murphy eye is a literal lifesaver. It’s the difference between a ventilator high-pressure alarm screaming in your ear and a patient who stays pink and oxygenated.
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Variations in the wild: Not all tubes are created equal
You’ll see a lot of different versions of this in a modern hospital.
- Reinforced (Armored) Tubes: These have a wire spiral embedded in the wall to prevent kinking. Most of these still incorporate a Murphy eye because if a patient bites down on a reinforced tube, you really need that secondary airflow path.
- RAE Tubes: Named after Ring, Adair, and Elwyn, these are pre-formed tubes used mostly in pediatric or facial surgeries. They almost always feature a Murphy eye because the acute angles of the tube increase the risk of the tip shifting against the tracheal wall.
- Dual-Lumen Tubes: Used in thoracic surgery to ventilate one lung. These are complex beasts, but the principles of the Murphy eye often apply to the bronchial tip to ensure the lobe doesn't collapse unnecessarily.
Real-world clinical pearls
If you are the one holding the laryngoscope, there are a few things you've got to keep in mind.
When using a Murphy eye endotracheal tube for a nasal intubation, that little side hole is a prime spot for catching a piece of turbinate tissue. It’s not uncommon to see a small "plug" of tissue sitting in the Murphy eye after a rough nasal pass. This is why many clinicians prefer the Magill tip for nasal routes, though the Murphy remains the standard for oral intubation.
Another thing: the Murphy eye can actually make suctioning a bit more difficult. If you're trying to clear a very specific area of the airway, the suction catheter might not follow the path you expect because of the internal geometry created by the eye.
The manufacturing side of things
It’s actually kind of fascinating how these are made. It's not just a hole punched in plastic. To maintain the structural integrity of the tube, the area around the Murphy eye has to be reinforced or carefully finished so it doesn't create a weak point where the tube could kink.
Manufacturers like Medtronic, Teleflex, and Smiths Medical have spent millions refining the "smoothness" of the eye. If you look at a cheap, off-brand tube versus a premium one, the first thing you'll notice is the finish on the Murphy eye. On a high-quality Murphy eye endotracheal tube, you can barely feel the transition with your finger. On a low-quality one, it feels like a jagged window.
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What's the future of airway design?
We’re starting to see "Smart" tubes and specialized coatings. Some researchers are looking at silver-coated tubes to prevent VAP (Ventilator-Associated Pneumonia). Does the Murphy eye interfere with these coatings? Generally, no. The design is so foundational that new tech has to wrap around it, not replace it.
There have been experimental designs with multiple "eyes" or different shaped openings, but they rarely make it to mass production. Why? Because the more holes you put in the tube, the more you compromise the "physics" of airflow and the structural strength of the PVC. One eye seems to be the "Goldilocks" zone—just enough safety without making the tube floppy or prone to tearing.
Making the right choice in the field
For 99% of patients, the Murphy eye endotracheal tube is the right choice. It’s the "seatbelt" of the airway world. You don’t think about it until you need it, and when you do need it, you’re incredibly glad it’s there.
If you’re a student or a new respiratory therapist, take a second during your next shift to actually look at the tube. Trace the path of air. Imagine the tip hitting the side of the trachea and see how the eye provides that "escape hatch" for the oxygen. It’s a masterclass in simple, effective medical engineering.
Actionable Next Steps for Clinicians
- Check your equipment: Always verify the patency of both the distal tip and the Murphy eye before intubation. A manufacturing defect that leaves a flap of plastic over the eye is rare, but it happens.
- Choose based on the route: If you’re performing a difficult nasal intubation and are worried about epistaxis or tissue trauma, consider if a Magill-tip tube (without the eye) might be more appropriate to reduce the "snag" risk, provided the patient's anatomy allows for it.
- Watch the stylet: When loading a stylet into a Murphy eye endotracheal tube, ensure the tip of the stylet does not poke through the eye. This is a common mistake that can lead to significant tracheal trauma during the procedure.
- Monitor Pressures: If you see a sudden "shark-fin" appearance on your capnography or a spike in peak inspiratory pressures, don't just assume the patient is biting the tube. The tip might be positioned against the wall, and the Murphy eye might be partially obstructed by secretions. A simple 1-2cm withdrawal or rotation of the tube can often clear the issue.
The Murphy eye is a tiny detail that carries the weight of patient safety on its shoulders. Understanding its strengths and its weird little quirks is what separates a technician from an expert in airway management. Look for the eye—it's there for a reason.