James M Rich, MA, CRNA1, Felice Agro, MD2, and Michael Frass, MD3
Instructor, Emergency Medicine Education, University of Texas
Southwestern Medical Center at Dallas
Address correspondence and comments to Dr. Michael Frass.
Received from the Emergency Medicine Education, University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA, the Department of Anesthesiology, University School of Medicine, Campus BioMedico of Rome, Rome, Italy, and the Department of Internal Medicine I, University of Vienna, Vienna, Austria.
This special article will be soon updated with digital images.
Statements: Support was provided solely from departmental and institutional sources. Dr. Michael Frass is patent holder of the esophageal-tracheal combitube.
Ventilation: esophageal-tracheal combitube.
Published: August 15, 2000.
The correct citation of this special article for reference is:
JM, Agro F, Frass M. The esophageal-tracheal
combitube for airway management in emergency situations. Internet
Journal of Airway Management 1: 2000-2001.
This special article will be regularly updated to take account of new data and comments on this version and will be supplemented with multimedia content, if there is material available.
Last updated: August 15, 2000.
Tracheal intubation is the overall accepted ”gold standard” of securing the airway and providing adequate ventilation. However, training in tracheal intubation requires time, a skilled endoscopist, appropriate instruments, and adequate circumstances with respect to space and illumination. Furthermore, tracheal intubation requires continued practice. The esophageal-tracheal combitube (ETC) functions as an effective alternative to tracheal intubation and is a valuable tool in difficult airway situations as well as in emergency airway management (1, 2).
Technical Aspects of the ETC
The ETC (manufactured by Tyco-Kendall, Mansfield, Massachusetts, USA) is available in two sizes: the ETC 37F SA (small adult) has been used successfully in male and female patients with a height between 120 to 198 cm and is recommended for use in patients 122 to 183 cm tall (3, 4); the ETC 41F is for use in patients with a height greater than 183 cm (5). The ETC design (see Figure 1) combines the benefits of a tracheal tube and an esophageal obturator airway (6). Two separated short tubes join to form one tube with a double lumen. The ETC is marked with two printed ringmarks at the proximal end of the double lumen part. After insertion, the patient’s teeth or alveolar ridges should lie between these rings. The large proximal oropharyngeal balloon (inflated with 85 ml of air with the ETC 37F SA and 100 ml with the ETC 41F, respectively) serves to seal the upper airway; the small distal cuff is inflated with 5 to 12 ml in the ETC 37F SA and 5 to 15 ml in the ETC 41F, respectively. While the oropharyngeal balloon may be inflated with additional 50 ml of air in case of insufficient seal, the maximum volumes of the distal cuff must never be exceeded in order to avoid damage to the structures of the esophagus or trachea (7). After placement, the distal cuff seals either the esophagus or the trachea.
Figure 1: Cross section of the esophageal-tracheal combitube.
Standard connectors (15 mm) are attached to the two proximal tubes of the ETC. The shorter clear tube number 2 is patent from the proximal to the distal end (resembling a tracheal tube). In the tracheal position, ventilation is performed through the shorter clear tracheal tube number 2 enabling it to function as a tracheal tube with inhalation and exhalation occurring through the open distal end of the tracheal lumen of the tube (see Figure 2). The longer blue pharyngeal (8) tube number 1 is patent at the proximal end and blocked at the distal end; pharyngeal perforations are provided at the pharyngeal level of the ETC for oxygenation and ventilation. Ventilation is performed through the longer blue esophageal tube number 1 when the ETC lies in the esophagus (see Figure 3). Therefore, the ETC provides effective lung ventilation and oxygenation with either esophageal or tracheal placement.
Figure 2: Ventilation through the shorter clear tube with the esophageal-tracheal combitube in the tracheal position.
Figure 3: Ventilation through the longer blue tube with the esophageal-tracheal combitube in the esophageal position.
Insertion of the ETC
Blind insertion is possible and requires only a brief course of instruction and practical training on manikins to gain competency (9-14). While the ETC may be placed blindly, the use of a Macintosh laryngoscope is recommended whenever available. It works equally well in either the esophageal (see Figure 3) or tracheal position (see Figure 2) and does not require movement of the head or neck in patients with evident or suspected cervical spine injury or cervical spine abnormalities (1, 11, 12, 15-18). The head remains preferably in a neutral position, a small cushion may be positioned under the head; some clinicians prefer to elevate the patient’s chin a little bit.
After mouth opening, the ETC is inserted in the midline of the mouth along the tongue (not along the pharyngeal wall) in a caudad direction (see Figure 4). Insertion at a right angle to the pharyngeal wall may cause resistance to advancement and might have been the problem of unsuccessful insertions in the early paramedic study by Atherton and Johnson (9).
Figure 4. Insertion of the esophageal-tracheal combitube.
Blind insertion results in esophageal placement in more than 95 percent of cases (9). The proximal balloon is inflated, followed by inflation of the distal cuff (see Figure 5). Inflation of the distal cuff before the proximal balloon might prevent the ETC from seating properly following its selfadjusting property (1, 9).
Figure 5. Inflation of the balloons of the esophageal-tracheal combitube.
When the ETC is placed in the trachea (7), it functions as a tracheal tube. While the oropharyngeal balloon might be deflated, it should be kept inflated especially during transport and prehospital care to prevent accidental extubation (1, 19, 20).
Application of the so-called Lipp-maneuver may further decrease the danger of soft tissue injury (personal communication, Lipp M, Mainz, Germany, 1999). This maneuver decreases the incidence of contacting the pharyngeal wall at a right angle, thus simplifying ETC insertion. The ETC is held bent between the two balloons for a few seconds; this accentuation of the curvature alleviates insertion along the tongue.
Ascertaining ETC Distal Tip Location
Auscultation of bilateral lung sounds, absence of insufflation over the epigastrium, and rise and fall of the chest are recognized as indicators of tracheal intubation. However, these methods may fail under difficult circumstances, especially during cardiopulmonary resuscitation (CPR) (21-24). Therefore, the need arises for alternatives.
The self-inflating bulb (SIB) (25) functions as an esophageal detector device (26). It helps to distinguish between tracheal and esophageal intubation. Only four seconds (27) are needed for the SIB to effectively determine ETC tip location (28). It has been shown to be a valuable tool for detecting correct tube placement.
The esophageal detection method is effective because of the structural dissimilarities between the trachea and esophagus. Hence the trachea is rigid because of the cartilaginous rings, the compressed SIB, attached to a tube communicating with the trachea and released, will rapidly re-inflate. Since the esophagus tends to collapse under application of a vacuum, the SIB will remain collapsed after attachment to a lumen leading to the esophagus (26, 28). The SIB may produce false negative results (tube communicating with trachea without re-inflation or slow re-inflation of SIB) in the following situations: in infants, asthmatic patients, morbid obesity, main stem bronchus intubation, and with tube obstruction.
Lung Ventilation with the ETC
In apneic patients, a bag-valve device used in conjunction with the ETC provides optimal lung ventilation. Continuous monitoring of lung ventilation is mandatory once location of the ETC tip has been confirmed. Capnometry or colorimetric breath indicators help to monitor position of the ETC and ventilation (29). However, in hemodynamically compromized patients the amount of carbon dioxide available for detection is decreased due to the reduced amount of blood in the pulmonary circulation. In these situations, carbon dioxide detectors may be ineffective in confirming proper breathing tube placement and can offer limited assistance in monitoring lung ventilation during low cardiac output states.
Use of the ETC in a Manikin
The following points should be carefully observed when training the insertion of the ETC in a manikin (30): the ETC and the mouth of the manikin should be sprayed with silicone or a similar substance to avoid adhesion of plastic against plastic; the mouth of the manikin should be opened with the thumb and index finger of one hand, the tongue grasped and pulled forward with the jaw, and the ETC passed gently into the patient's pharynx. Depending on the situation, we recommend insertion under laryngoscopic view specially in elective cases. Insertion may be difficult in certain types of manikin heads. The manikin head fanufactured by Ambu Inc (Linthicum, Maryland, USA) may be the most difficult to use since the pharyngeal area is open at the side and the ETC may be displaced. The manikin heads manufactured by Laerdal (Stavanger, Norway) work well, but the head has to be slightly extended, otherwise the ETC cannot be fully inserted. The best manikin head for the ETC is manufactured by VBM Medizintechnik (Sulz am Neckar, Germany). With all manikins, the ETC has to be inserted along the tongue using a curved downward movement with the lower part parallel to the chest. Insertion may be easier when the ETC is inserted with a rocking motion. Bending of the ETC at the pharyngeal portion between the balloons for a few seconds (the so-called Lipp-maneuver) enhances the preformed curvature and makes placement even more rapid. Furthermore, the fixation of the ETC after inflation of the oropharyngeal balloon without the need for tape saves time in cardiopulmonary resuscitation.
With these points in mind, the ETC has been inserted by thousands of participants in airway workshops within 10 to 20 seconds and it was assumed that ETC insertion was the quickest and easiest to learn compared to other alternative airways. Of course, insertion in patients is made easier by a moist mucosa compared with the dry plastic material of manikin heads.
Use of the ETC in the Prehospital Setting and in Trauma Patients
The ETC is increasingly being used for prehospital airway management (9, 10, 14, 17, 35, 36). In an early study, paramedics successfully inserted the ETC 71% of the time when used as a first-line airway adjunct (9). Atherton and Johnson reported a nearly 100 % success rate when the ETC was trained repeatedly thereby allowing skill retention (9). In a prospective study, flight nurses were trained in the use of the ETC and consistently inserted the ETC after two or more failed attempts at orotracheal rapid sequence intubation (10). Seven of the patients were suffering from mandibular fractures, four from traumatic brain injury, two from facial fractures, and one from hemopneumothorax. Four of the patients were discharged home, three transferred to inpatient rehabilitation. The ETC was rated best in a study comparing the device with the pharyngeal-tracheal lumen airway, the laryngeal mask airway (LMA), and the oropharyngeal airway with mask when used in conjunction with a bag-valve device by emergency medical technicians (EMTs) during cardiorespiratory arrest. Success rate of insertion and ventilation was significantly higher with the ETC (86% successful insertion rate) despite the fact that some of the EMTs had been previously trained to use the LMA in the operating room (36). In the ETC group, blood gas analyzes showed a lower mean arterial partial pressure of carbon dioxide, a higher arterial partial pressure of oxygen, and a higher mean exhaled volume when compared with the pharyngeal-tracheal lumen airway, LMA, and oropharyngeal airway with mask. EMTs rated the ETC best in overall performance and adequacy of airway patency and ventilation in comparison to the other devices (36).
In a retrospective study of 12,020 cases of non-traumatic cardiac arrest, Tanigawa and Shigematsu (14) found the ETC to have a better first attempt insertion rate (82.4%) than either the esophageal gastric tube airway or the LMA. Also, success rate for ventilation and for insertion and ventilation was significantly higher with the ETC. A single case of aspiration was observed with the use of the ETC. In a series of 1498 patients, the Emergency Medical System of Quebec, Canada, reported a 98% insertion success rate (personal communication, Lefrancois D, Quebec, Canada, 1999).
The ETC worked well in sniffing and in neutral position when a rigid cervical collar was applied after intubation as tested in 40 patients undergoing routine surgery. The results of this study are of interest in patients with suspected or evident cervical spine injury (20). In a comparison of the LMA and ETC, it was shown that the ETC was a suitable alternative to the LMA for use by unskilled staff (5). In a study by Haynes and co-workers (37) it was shown that all ETC placements were located correctly by rural EMTs with selected advanced skills. Overall treatment was judged 94 % appropriate, with improvement in 60 % of patients. The ETC was used successfully for elective airway management in a patient with cervical spine fracture (38). In a comparative study of bag-valve-mask, LMA, and ETC in a bench model, it could be shown that there was no gastric inflation when ventilation was performed with the ETC as compared to the other two devices (19). Lung volumes were also highest with the ETC.
Case Reports of Special Interest
Massive nasal hemorrhage happened during elective surgery after attempted nasotracheal intubation. This situation was managed with the help of an ETC (39). Another case report of rapidly developing cervical haematomas from inadvertent carotid puncture complicating central line placement describes the use of the ETC in two cases in which direct laryngoscopy was not possible and the airway was in immediate danger (40). Massive oropharyngeal hemorrhage in a patient on thrombolytic therapy prevented visualization of the vocal cords (41). Since laryngoscopy as well as fiberoptic intubation were not possible, the ETC was used and worked well.
Two other patients, one with limited mouth opening and the other with profuse vomiting during intubation, were successfully ventilated with the ETC (42). In both cases tracheal intubation had failed and mask ventilation was extremely difficult. In a patient with severe rheumatoid arthritis it was impossible to intubate with a standard tracheal tube, therefore a secure airway was maintained with the ETC (29). The procedure was completed without complications, and extubation was performed with the patient awake at the end of general anesthesia. The ETC was used successfully in a patient whose neck and pharynx were impaled by a piece of fence and the neck could not be mobilized without the acute danger to the anatomical structures (12). This situation prevented laryngoscopy, therefore the ETC was used to ventilate the patient's lungs until an emergency tracheotomy could be performed.
Advantages of the ETC
The ETC allows prompt and effective airway management in the prehospital setting, in the emergency department, and beyond. In case of unsuccessful tracheal intubation (10, 12, 15, 16, 35, 41) due to either lack of equipment or expertise, the ETC facilitates control and protects the airway of unconscious patients at risk of airway obstruction with or without the need for lung ventilation. The skills necessary to use the ETC are easily achieved especially by untrained personnel (5, 9-11, 14, 36). Nurses who were untrained in tracheal intubation were able to perform blind insertion and ventilation with the ETC faster than intensive care physicians with tracheal intubation using direct laryngoscopy (11).
The ETC needs no preparation and it is effective when either working space or ambient light are limited (15). Ease of insertion allows rapid intubation regardless of the patient's position. After inflation, the oropharyngeal balloon anchors strongly behind the hard palate (1) thereby securing the airway during transport and ventilation and decreasing the danger of accidental extubation (1, 19).
The ETC minimizes the danger of pulmonary aspiration. The design of the proximal balloon and the distal cuff protects the airway from esophageal and gastric contents, blood, and debris (12). In the esophageal position, the unused so-called “tracheal“ lumen also helps to decrease the likelihood of aspiration by immediate decompression of the stomach (4) and by provision of a route for evacuation of gastric fluid (see Figure 6) (11, 17).
Limitations and Contraindications of the ETC
The ETC has some limitations and contraindications (1) which must be understood before use in clinical practice; it should not be used in patients with an intact gag reflex, known esophageal pathology, ingestion of caustic substances, supraglottic stenoses, or tumors. In case of a glottic or subglottic obstruction an airway has to be placed with its opening below the obstruction using either an tracheal tube, transtracheal jet ventilation, or a surgical airway.
Reported Complications of the ETC
Although infrequent, complications with the ETC have been reported. Ventilation via the ETC is not possible in case of deep insertion (43), because the oropharyngeal balloon might lead to a partial or total obstruction of the laryngeal aperture. In this case, the ETC has to be withdrawn for about 2 to 3 cm until the lungs can be ventilated through the longer blue tube port. Tanigawa and Shigematsu (14) stated that even though some level of limitations, disadvantages or complications were apparent with all the airway devices they reviewed, the ETC had comparatively fewer limitations, disadvantages, or complications overall.
There are several reports of esophageal perforation associated with use of the ETC (7, 14, 44). Therefore, the use of the ETC in elective patients with known esophageal disease should be avoided. In a study including 1139 insertions of the ETC, two esophageal lacerations reported might have been caused by overinflation of cuffs with 20 to 40 ml of air used in the distal cuff and 140 ml of air in the proximal balloon (7). Overfilling of the cuffs should therefore be avoided. The distal cuff volume should never exceed a maximum of 12 ml of air with the ETC 37F SA and 15 ml with the ETC 41F. In elective cases, the oropharyngeal balloon should be inflated with only 40 ml (ETC 37F) and 70 ml (ETC 41F) of air using the minimal leakage technique and thereby avoiding any potential stress to the pharyngeal mucosa. However, in emergencies, there is no time for this maneuver until stabilization of the patient’s situation. In the study by Tanigawa and Shigematsu (14), one case of esophageal perforation and one case of subcutaneous emphysema might have been caused by the ETC or the automatic compression device or a combination of both.
Due to its smaller size, the ETC 37F SA is easier to use and appears to be less traumatic to the mucosa and soft tissues (3). Therefore, it is recommended to use the ETC 37F SA in patients with a height from 120 to 180 cm (3 ,4).
Thirty percent of the deaths of trauma victims may be attributed to airway and/or breathing dysfunction as well as extracranial hemorrhage. Research has revealed that airway intubation is potentially capable of extending a trauma victim's ability to tolerate circulatory arrest.
Background reading, didactic and video instruction along with manikin training and testing should add no more than three hours to the course. A recent study has shown the value of lecture, video tape, and manikin training for advanced combat airway management by military paramedics (45). As with all similar devices, refresher training and testing would need to re-occur at regular annual intervals (9).
The ETC has been included as an appropriate alternative for ”can’t ventilate - can’t intubate” situations in the American Society of Anesthesiologists Difficult Airway Algorithm (46), as a class IIa device to the guidelines of the American Heart Association for advanced cardiac life support (47), and as an alternative to failed tracheal intubation in the advanced airway management algorithm of the Airway and Ventilation Management Group of the European Resuscitation Council (48), the Difficult Airway Society (United Kingdom), and the Italian Society of Anesthesia, Resuscitation, and Intensive Therapy (49). It is a valuable addition to the difficult airway cart in any facility dealing with emergency intubation situations. It can be easily stored packed in a tray, roll-up kit, or single kit.
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