What Is an Airway Exchange Catheter?

An airway exchange catheter (AEC) is a long, thin, hollow tube placed through an existing breathing tube before that tube is removed, serving as a temporary guide rail so that if the patient needs to be reintubated, a new tube can be threaded back into the trachea without starting from scratch. These devices are most often used in patients whose airways are known to be difficult to manage, where losing access even briefly could be dangerous or fatal. While AECs have become a standard part of difficult-airway strategy in operating rooms and intensive care units, they carry their own set of risks, and the evidence on how well they work reveals a more complicated picture than the concept might suggest.

What the Device Actually Looks Like and Does

An AEC is essentially a semi-rigid hollow catheter, typically made of polyethylene or a similar medical-grade plastic. It comes in several sizes, commonly measured in French gauge. A standard adult size is around 11 to 14 French, which translates to roughly 3.7 to 4.7 millimeters in outer diameter. The catheter is long enough to extend from outside the patient’s mouth down past the vocal cords and into the trachea, usually around 80 centimeters or so. The hollow center, or lumen, serves two purposes: it allows supplemental oxygen to be delivered directly into the airway, and it provides a channel over which a new endotracheal tube can be railroaded if reintubation becomes necessary.

During a planned extubation in a patient with a difficult airway, the AEC is threaded through the existing endotracheal tube before that tube is pulled out. Once the endotracheal tube is removed, the catheter stays in place, taped or secured at the mouth or nose, with its tip sitting in the trachea. In one early prospective study, patients were extubated over a Cook airway exchange catheter, and humidified oxygen was insufflated through the lumen at 2 to 8 liters per minute for a minimum of four hours while oxygen saturation and breathing rate were monitored.¹ That dwell time gives clinicians a safety window: if the patient deteriorates, they can slide a new tube over the catheter rather than scrambling to re-visualize a potentially swollen or distorted airway.

Why Clinicians Reach for One

The primary indication is any extubation where reintubation might be difficult. That includes patients with known anatomical challenges like a short neck, limited jaw opening, or prior difficult intubations. It also includes patients whose airways may have changed during a procedure or ICU stay: facial or neck surgery, prolonged intubation causing swelling, trauma to the airway structures, or surgery near the trachea or esophagus. Maintaining continuous access to the airway after extubation via an indwelling AEC appears to improve the first-pass success rate for reintubation in these patients and reduce complications when reintubation is needed.²

AECs are also used for tube exchanges, not just extubations. A common scenario in thoracic surgery is switching from a single-lumen endotracheal tube to a double-lumen tube, which allows the anesthesiologist to ventilate each lung independently. The catheter bridges the gap: the old tube comes out over the catheter, the new tube goes back in over the same catheter, without ever losing tracheal access. In double-lumen tube replacement specifically, inserting the exchange catheter through the bronchial lumen under video guidance has been recommended as the safer route.³

Success Rates Are Not as High as You Might Expect

The concept sounds straightforward: leave a guide in place, slide the tube over it. In practice, things go wrong more often than clinicians might assume. A large single-center study looking at 1,177 cases found that intubation failed in about 14% of attempted tube exchanges performed over an AEC.⁴ That is not a trivial failure rate for a device whose entire purpose is to make reintubation easier.

Failure rates varied substantially depending on the clinical scenario. The highest failure rates in that study occurred during double-lumen tube insertions and when clinicians attempted to reintubate over the catheter in the postoperative period. One reason is mechanical: double-lumen tubes are bulkier and stiffer than standard single-lumen tubes, which makes railroading them over a relatively flexible catheter more challenging. Separate case data has reported that failure rates for exchanging a single-lumen tube to a double-lumen tube can approach 40%.⁵ Using an extra-firm catheter designed specifically for double-lumen exchanges can help, but availability varies between institutions.

The other contributor to failure is anatomy and timing. In a postoperative patient whose airway has become edematous or whose secretions have accumulated, the catheter may be in the right place but the new tube still hangs up on swollen tissue at the vocal cords or arytenoids. The catheter provides a path through the glottis, but it does not dilate the tissue around it.

Oxygen Delivery and the Barotrauma Problem

One of the most useful features of an AEC is also one of its most dangerous. Because the catheter is hollow, clinicians can push oxygen through it to help maintain the patient’s oxygen levels while the airway is unsecured. This is genuinely helpful: even modest oxygen flow through the catheter buys critical time during a difficult reintubation attempt. An in vitro study found that AECs could deliver clinically useful oxygen flows of roughly 3.4 to 9.4 liters per minute when the distal pressure was limited to 30 centimeters of water.⁶

The danger lies in what happens when pressure is not limited. If high-pressure oxygen, particularly jet ventilation, is delivered through the catheter without adequate safeguards, the results can be catastrophic. The narrow lumen of the catheter creates a high-velocity, high-pressure stream of gas that can overdistend and rupture lung tissue. A review of the literature on AEC oxygen supplementation found that the only published case series using jet ventilation through an AEC reported an 11% rate of pulmonary barotrauma. Thirteen individual case reports documented jet ventilation through an AEC causing pneumothorax, air leaking into the chest cavity’s middle compartment, air in the abdomen, cardiovascular collapse, and death.⁷

One published case illustrates the severity well: a patient received supplemental oxygen through an AEC and developed massive subcutaneous emphysema and bilateral tension pneumothoraces, meaning both lungs were being compressed by trapped air.⁸ This was not jet ventilation gone wrong in a high-stakes rescue scenario; it was oxygen supplementation during what was intended to be a controlled process. The takeaway for clinical teams is stark: even low-flow oxygen through an AEC requires attention to pressure limits, and jet ventilation through one should be treated as a last resort with very careful pressure regulation, not as a routine strategy.

Direct Airway Injury

Barotrauma from oxygen delivery is not the only complication. The catheter itself is a semi-rigid tube sitting inside a soft, mobile airway, and it can cause direct mechanical injury. Reported complications include damage to the vocal cords, perforation of the bronchus, and puncture of the tracheal wall. In one case, reintubation performed over an AEC resulted in a posterior laceration of the right main bronchus, leading to a large pneumothorax that was visible on chest X-ray and confirmed on bronchoscopy.⁹

This kind of injury tends to happen when the catheter tip advances too far, particularly into a mainstem bronchus, or when force is applied during a reintubation attempt. The catheter can act as a rigid lever against the bronchial wall as a new tube is pushed over it. Insertion depth matters: leaving too much catheter inside the trachea increases the risk of distal airway perforation, while pulling it back too far risks losing tracheal access entirely. This is a judgment call that depends on the patient’s height, anatomy, and the clinical situation, and it is one of the reasons AEC use requires training and experience beyond just knowing what the device is.

Video Laryngoscopy Has Changed the Game

For years, tube exchanges over an AEC were performed using traditional direct laryngoscopy, where the clinician uses a blade to lift the tongue and directly views the vocal cords. Video laryngoscopy, which uses a camera on the blade tip to project an image on a screen, has substantially improved outcomes in this setting. A study comparing the two approaches in high-risk difficult airway patients found that video laryngoscopy raised the first-pass success rate for tube exchange from about 68% to over 91%.¹⁰

The improvement was not just about getting the tube in on the first try. Patients managed with video laryngoscopy also had lower rates of low oxygen episodes, esophageal intubation (where the tube accidentally goes into the food pipe instead of the airway), slow heart rate events, and the need for rescue airway devices. The number of patients requiring three or more attempts dropped from about 7% with direct laryngoscopy to around 1% with video.¹¹ The message for practice is that an AEC alone is not the entire safety net. Combining it with video laryngoscopy produces meaningfully better outcomes than using the catheter with traditional technique.

How AECs Compare to Other Airway Adjuncts

AECs are not the only devices used to bridge airway access during tube exchanges. The gum elastic bougie, a familiar tool in emergency airway management, and the Aintree intubation catheter are sometimes used in similar roles, though they have different design characteristics. The Aintree catheter is wider, with an external diameter of about 19 French (6.5 mm) compared to the bougie’s 15 French (5 mm). A cadaver study comparing the two for airway exchange through a supraglottic airway device found that the size difference did not meaningfully affect performance on either primary or secondary outcomes.¹²

The meaningful differences between devices tend to be situational rather than universal. A standard AEC’s main advantage is its hollow lumen, which allows oxygen delivery, something a solid bougie cannot do. The Aintree catheter is also hollow and wider, which makes it better suited for fiberoptic-guided techniques but too large for some tube sizes. The choice often depends on what is available, what the clinician is trained on, and the specific clinical problem at hand. There is no single device that outperforms the others in all scenarios.

Intraluminal Versus Extraluminal Technique

When exchanging an airway device using a catheter, there are two broad approaches. In the intraluminal technique, the exchange catheter is threaded through the inside of the existing tube or supraglottic device, and the new tube is then railroaded over it. In the extraluminal technique, the new tube is placed alongside the catheter rather than over it. A simulation study comparing the two found that the intraluminal approach was significantly faster, with a median time to establish endotracheal intubation of about 78 seconds versus 140 seconds for the extraluminal method.¹³ The failure rate was identical between the two groups in that study, but speed matters when a patient is desaturating.

Patient Tolerance and Comfort

Something that rarely comes up in the technical literature but matters a lot in practice is that having an AEC left in place after extubation is uncomfortable. The catheter passes through the nose or mouth, sits across the back of the throat, and extends through the vocal cords. Awake patients cough, gag, and may try to pull it out. Inadequate sedation or topical anesthesia can turn a well-planned extubation strategy into a wrestling match that defeats the purpose of the catheter entirely.

Most protocols call for topical anesthesia applied to the airway before extubation and, often, light sedation to improve tolerance. Securing the catheter carefully is also critical: a catheter that migrates out of the trachea because the patient coughed it up is no longer a safety device. The flip side is that over-sedating the patient to keep the catheter in place can itself cause airway obstruction, defeating the purpose of extubation. Striking this balance is part of the clinical art that makes AEC management more demanding than it appears on paper.

When an AEC Is Not the Right Choice

Not every difficult airway patient needs an AEC left in place after extubation. In patients whose airway difficulty was purely related to the intubation angle or anatomy but whose extubation risk is low, leaving a foreign body across the vocal cords introduces risks without proportionate benefit. Similarly, in patients who are expected to be fully awake and cooperative, and whose airway swelling is minimal, the discomfort and coughing caused by the catheter can create more problems than it solves.

The decision to use an AEC at extubation is a risk-benefit calculation that considers the patient’s specific anatomy, the reason their airway was difficult in the first place, whether that difficulty is likely to be the same or worse on reintubation, and the clinical setting. An ICU with full airway equipment and experienced staff at the bedside is a different context from an operating room at the end of a routine case. Guidelines from airway management societies generally recommend AEC use as part of an extubation strategy for patients at elevated risk, but they do not recommend it for every intubated patient. The device is a safety net for specific high-risk situations, not a universal precaution.

Training and Familiarity Gaps

One underappreciated problem with AECs is that many clinicians rarely use them. In anesthesia training programs, trainees may see only a handful of AEC-guided extubations or tube exchanges during their entire residency, because the situations that call for them are relatively uncommon. This creates a familiarity gap: the device is most needed in high-stress, high-stakes moments, which are exactly the wrong times to be using something you have only handled a few times. Simulation-based training can partially close this gap, and studies using manikins and simulation scenarios have been used to compare techniques and build procedural confidence. But simulation cannot fully replicate the tissue compliance, secretions, and stress of a real difficult airway, so hands-on experience during elective cases remains valuable when the opportunity arises.

The broader point is that an AEC is a tool, and like any tool, its effectiveness depends heavily on the skill and judgment of the person using it. The failure rates and complication reports in the literature are not indictments of the device itself but reflections of how challenging the clinical scenarios are in which it is deployed. A catheter that works perfectly in a calm, planned tube exchange can fail in a chaotic emergency reintubation, not because the catheter changed but because the conditions did.