The Combitube is a double-lumen emergency airway device designed to ventilate a patient regardless of whether it lands in the esophagus or the trachea. Developed in the 1980s as a hybrid between an esophageal obturator airway and a standard endotracheal tube, it became a staple in prehospital emergency care because it can be inserted blindly, without a laryngoscope or a direct view of the vocal cords. That feature made it especially useful for paramedics and emergency medical technicians managing cardiac arrest in the field, though newer supraglottic devices have since claimed much of its territory.
How the Device Works
The Combitube is a plastic tube with two separate channels running side by side, each ending in its own connector at the top. It has two inflatable balloons: a large oropharyngeal balloon in the middle portion of the tube that seals off the mouth and nose from below, and a smaller cuff at the distal tip that seals whichever structure the tip enters. The two lumens are divided by an internal wall. One lumen, marked with a blue connector, is closed at the bottom but has eight small perforations between the two balloons. The other lumen, with a clear connector, is open at the bottom like a conventional breathing tube.
The critical design insight is that it does not matter where the tip goes. In the vast majority of blind insertions, the tip slides into the esophagus rather than the trachea. When that happens, the provider ventilates through the blue (pharyngeal) lumen. Air exits through the eight perforations into the throat, and because the large upper balloon blocks the mouth and nose while the lower cuff seals the esophagus, the only place air can go is down through the vocal cords into the lungs. If the tip happens to land in the trachea instead, the provider simply switches to the clear lumen, which then functions like a standard endotracheal tube.
Inserting the Combitube
Insertion does not require a laryngoscope or any visualization of the airway. The provider lifts the jaw, slides the Combitube along the curve of the tongue until resistance is felt, and inflates both balloons. The first step after inflation is to attempt ventilation through the blue connector, since esophageal placement is far more common. If the provider hears breath sounds in the chest and no gurgling over the stomach, the tube is in the esophagus and ventilation continues through the blue lumen. If chest sounds are absent and the stomach inflates instead, the tip is in the trachea, and the provider switches to the clear connector without repositioning the device.
This “try one lumen, then try the other” protocol is part of what made the Combitube attractive for providers with limited intubation experience. It essentially turns a potential misplacement into a non-event, because both positions work as long as the correct lumen is selected.
Clinical Performance in Cardiac Arrest
The Combitube saw its heaviest real-world use in out-of-hospital cardiac arrest. A study of 760 cardiac arrest patients managed by basic emergency medical technicians found that placement was successful in about 95% of cases, with effective ventilation achieved in roughly 91%. Among 133 of those patients who underwent autopsy, no esophageal lacerations or significant airway injuries were found.
The more pressing question for emergency systems was whether patient outcomes differed when technicians used a Combitube versus when paramedics performed standard endotracheal intubation. A large observational study comparing the two approaches in out-of-hospital cardiac arrest found no meaningful difference. Rates of return of spontaneous circulation, survival to hospital admission, and survival to hospital discharge were statistically comparable between the groups.
That result matters because endotracheal intubation requires substantially more training, a laryngoscope, and often medications for sedation. If a simpler blind-insertion device produces equivalent survival, the practical argument for the Combitube in the field was strong. Paramedics also used the device as a backup when rapid sequence intubation failed, and it proved effective in that salvage role in high-volume urban and suburban EMS systems. In the hospital setting, it served as a secondary rescue device when both a bougie-assisted intubation and a laryngeal mask airway had failed.
How It Compared to Other Devices
Several studies pitted the Combitube against competing airway devices, and the results generally favored the Combitube on speed and ease of use, even if ventilation quality was similar across the board.
In a manikin study comparing inexperienced and experienced emergency staff, the median time to secure an airway with the Combitube was about 5 seconds, versus roughly 17 seconds for endotracheal intubation. The failure rate with endotracheal intubation was also significantly higher. A study involving ICU nurses during actual cardiac arrests found that nurses placed the Combitube faster than intensivists placed endotracheal tubes, and blood gas readings were comparable. Arterial oxygen levels were actually slightly higher during Combitube ventilation in that study.
A randomized prehospital trial involving 470 cardiac arrest patients compared the Combitube against a pharyngeal-tracheal lumen airway, a laryngeal mask, and a standard oral airway. Successful insertion and ventilation rates were highest for the Combitube at 86%, compared with 82% for the pharyngeal-tracheal lumen device and 73% for the laryngeal mask. Objective measures of ventilation, including blood gases and spirometry, showed no significant differences, but emergency medical assistants reported fewer ventilation problems with the Combitube and rated it their preferred device. It was also the most expensive option in that trial.
One unusual comparison tested the Combitube and endotracheal tube during parabolic flights simulating microgravity. The Combitube performed equally well in normal gravity and weightlessness, while endotracheal intubation was significantly slower in microgravity. The finding had implications for aerospace medicine, though for most EMS systems it was the terrestrial speed advantage that mattered.
Aspiration Protection
One area where the Combitube stood out from other supraglottic airways was its resistance to aspiration, meaning stomach contents leaking past the device into the lungs. A cadaver study measured oesophageal leak pressures across several device types. Laryngeal masks showed a baseline leak pressure of about 28 cm of water pressure, but that dropped sharply to 8 or 9 cm when the cuff was overinflated or when pressure was applied to the neck. Laryngeal tubes held up better at baseline (68 cm) but still dropped to 37-39 cm under those conditions. The Combitube, by contrast, maintained leak pressures around 126 to 130 cm of water regardless of overinflation or neck pressure, because its design physically obstructs the esophagus with a dedicated cuff rather than relying on a seal around the larynx.
This is a meaningful practical difference. During CPR, chest compressions push on the stomach and raise the risk of regurgitation. A device that blocks the esophagus directly rather than sitting over the laryngeal inlet offers a more reliable barrier. For patients who have not fasted, such as virtually every cardiac arrest victim encountered in the field, that added protection mattered.
Complications and Safety Concerns
The most widely discussed complication is esophageal injury. In one case series drawn from over 1,100 resuscitations, eight patients developed subcutaneous emphysema (air under the skin). Among four patients who underwent autopsy, two had large longitudinal tears of the esophageal wall measuring 6 and 6.5 centimeters. A third patient had multiple shallow lacerations of the esophagus. These injuries were linked to the device’s rigid construction and the large pharyngeal balloon, and they could lead to pneumomediastinum or pneumoperitoneum. The rate was low relative to the total number of insertions, but the severity of a full-thickness esophageal tear is serious enough that it shaped how providers thought about the device’s risk profile.
It is worth noting that the larger study of 760 patients mentioned earlier found no esophageal injuries on autopsy, which suggests the complication rate varied across settings and may have been influenced by insertion technique, balloon inflation volumes, or the condition of the patient’s tissues.
Tongue Engorgement
A less intuitive complication involves the tongue swelling dramatically after the Combitube has been in place for an extended period. The large oropharyngeal balloon compresses the blood vessels that drain the tongue, particularly the lingual veins. In one reported case, significant tongue swelling appeared roughly four hours after an uneventful insertion, eventually requiring an emergency tracheostomy before the Combitube could be safely removed.
A controlled study quantified the problem. When the Combitube was placed in the standard midline position, tongue engorgement occurred in 67% of patients. When the device was shifted to a lateral position in the mouth, that rate dropped to 17%. In both groups, the longer the device stayed in place, the worse the swelling became. This finding reinforced that the Combitube was designed for short-duration emergency use, not prolonged ventilation. Providers were advised to transition to a definitive airway, such as an endotracheal tube or surgical airway, as soon as the clinical situation allowed.
Who Can and Cannot Use One
The Combitube came in two sizes. The larger 41-French model was intended for adults over about 180 centimeters tall, and the smaller 37-French SA model was recommended by the manufacturer for patients between 122 and 152 centimeters. Research expanded that range: a study of anesthetized adults found that the 37-French SA model provided effective and reliable ventilation in patients up to 185 centimeters tall, and established a direct relationship between patient height and the volume of air needed in the pharyngeal balloon.
The device was never intended for small children. Below about 122 centimeters, there was no appropriately sized version. Other contraindications included patients with known esophageal disease, those who had ingested caustic substances, and anyone with an intact gag reflex, since the device’s bulk in the oropharynx would provoke severe retching in a conscious or semi-conscious person. Patients with upper airway obstruction from masses or severe swelling were also poor candidates, because the tube still needs to pass through the oropharynx to reach the esophagus or trachea.
The Training Problem
One of the Combitube’s selling points was that it required less training than endotracheal intubation. That was true, but “less” did not mean “none,” and skill retention turned out to be a real weakness. A follow-up study assessed 11 randomly selected paramedics 15 months after their initial Combitube training and field use. Nine of the 11 demonstrated inadequate skill retention. The authors concluded that comprehensive training and continuing education were essential despite the device’s relatively simple design.
A separate study measured skill decay more formally. Initial testing showed that subjects could successfully ventilate a manikin with the Combitube in 92% of attempts. At retesting some time later, the success rate dropped to 77%. By comparison, the laryngeal mask airway showed a smaller, non-significant decline from 90% to 85%. The statistically significant decay for the Combitube but not for the laryngeal mask hinted that the Combitube’s two-lumen, two-balloon system introduced enough complexity that the steps faded from memory faster than expected.
This skill retention gap became one of the factors that eroded the Combitube’s dominance in prehospital care. If a device requires frequent refresher training to maintain competency, and if a simpler alternative like the laryngeal mask or i-gel achieves comparable outcomes with a shallower learning curve and better retention, EMS systems have a practical reason to switch.
Where the Combitube Came From
The Combitube was developed by Michael Frass and colleagues in Austria and first reported in 1987. Their initial publication described the twin-lumen design and tested it in a crossover study of 31 patients undergoing routine surgery, comparing ventilation with the Combitube in the esophageal position against a standard endotracheal airway. Blood gas measurements showed significantly higher mean arterial oxygen levels during Combitube ventilation. Preliminary use in 21 cardiac arrest patients suggested the device was as effective as standard intubation during CPR.
The timing mattered. In the late 1980s and through the 1990s, prehospital airway management was a genuine problem. Endotracheal intubation in the field had high failure rates among non-physician providers, and the older esophageal obturator airway was falling out of favor due to its own complications and limitations. The Combitube filled a gap by being harder to misuse than either predecessor. It became widely adopted across North American and European EMS systems throughout the 1990s and 2000s, and was included in multiple resuscitation guidelines as an acceptable alternative to endotracheal intubation.
Why It Has Largely Been Replaced
Despite its track record, the Combitube gradually lost ground to newer supraglottic airway devices, particularly the laryngeal mask airway family and the King Laryngeal Tube (now marketed as the King Vision LT). Several factors drove the shift. The tongue engorgement issue limited how long the Combitube could safely remain in place. The rigid construction and large pharyngeal balloon created a non-trivial risk of esophageal trauma. The device was bulky, came in only two adult sizes, and could not be used in children. Skill retention proved worse than with simpler alternatives.
Meanwhile, newer supraglottic airways offered a gentler profile. Devices like the i-gel required no cuff inflation at all, reducing insertion steps and eliminating balloon-related complications. Laryngeal tubes were available in a wider range of pediatric and adult sizes. Both categories showed comparable ventilation effectiveness in cardiac arrest studies while being easier to teach and maintain competency with. Many EMS systems, particularly in North America, transitioned away from the Combitube during the 2010s.
The Combitube has not disappeared entirely. It still appears in difficult airway algorithms as a rescue option, and some services retain it for situations where other supraglottic devices fail. Its aspiration protection remains superior to laryngeal mask airways under adverse conditions, which gives it a niche role in patients at very high risk of regurgitation. But for routine prehospital airway management, it has been largely superseded by devices that trade a fraction of the Combitube’s seal quality for a substantially simpler user experience.
The Combitube in Unusual Environments
The Combitube attracted interest beyond standard ambulance-based care because its blind insertion technique made it appealing wherever visualization of the airway was impractical. The parabolic flight study demonstrated that the device performed identically in weightlessness and normal gravity, with insertion times unchanged at roughly 18 to 19 seconds, while endotracheal intubation slowed significantly in microgravity. That result led to the Combitube being considered for space medicine applications, where a provider attempting intubation would be floating alongside an unstable patient in a confined module.
Similar logic applied to austere or confined environments on Earth: tactical medicine, wilderness rescue, and mass casualty incidents where providers may be working in poor lighting, cramped spaces, or while wearing protective equipment that limits dexterity. The device’s tolerance for imperfect conditions was its core strength, and in scenarios where the newer, softer supraglottic devices might not provide an adequate seal against contamination or regurgitation, the Combitube’s aggressive two-cuff design retained a theoretical advantage. Whether that advantage translated to better clinical outcomes in those specific scenarios was never convincingly tested in large studies, which is one reason the Combitube’s decline continued despite occasional arguments for its revival in niche roles.