The purpose of this study is to evaluate a new supra-glottic airway device, the "Disposable
Laryngeal Tube Suction" (LTS-D; King Systems, Noblesville, IN). We propose to test its ease
of insertion, position within the airway, patency of drain tube and anatomic sealing
properties during spontaneous ventilation in anesthetized patients. The study device will
be compared to the ProSeal Laryngeal Mask Airway (PLMA, LMA North America Inc.) and the
Esophageal Tracheal Combitube (ETC; Tyco Healthcare/Mallinckrodt Nellcor, Pleasanton,
During the past decade, several pharyngeal airways have been introduced into clinical
practice for airway management, such as the Laryngeal Mask Airway (LMA), the Cuffed
Oropharyngeal Airway (COPA), the Esophageal Tracheal Combitube (ETC), and most recently, the
Laryngeal Tube (LT). These airway devices have become very popular because of their ability
to maintain an airway without perturbing the trachea, and can be used in patients without
muscle relaxation and who are only lightly anesthetized.
The LMA generally provides an adequate airway, but certain problems remain. (1) In 8-33% of
LMA placements, more than one attempt is required. (2) It is sometimes difficult to advance
the LMA without extending the neck (which is contraindicated in some patients). (3) The
device does not protect the airway from aspiration of gastric contents. (4) It does not
provide an airtight seal around the larynx (the usual pressures causing leakage of gas being
15-20 cm H20). Consequently, the device functions poorly during positive-pressure
ventilation. (5) The esophagus is included within the rim of the LMA in 10-15% of patients,
directly exposing the esophagus to positive airway pressures. This often results in
insufflation of the stomach and postoperative discomfort.
The ETC is a disposable double-lumen tube that combines the features of a conventional
endotracheal tube with those of an esophageal obturator airway. It is appropriate for
prehospital, intraoperative, and emergency use and is especially useful for patients in whom
direct visualization of the vocal cords is not possible, patients with massive airway
bleeding or regurgitation, limited access to the airway, and patients in whom neck movement
is contraindicated. Ventilation with the ETC is possible with either tracheal or esophageal
intubation, as its distal cuff seals off the esophagus to prevent aspiration of gastric
contents. The ETC has a 6.9% incidence of placement failure and a failed ventilation rate of
The Laryngeal Tube Suction (LTS; VBM Medizintechnik; King Systems, Noblesville, IN) is a
supra-glottic airway device designed to provide a more effective seal than the LMA, thus
eliminating problems 3-5 described above. The insertion of the standard laryngeal tube is
generally easy. The reported success rate of insertion of, and ventilation through, the
laryngeal tube ranges from 92-100% for the earlier prototype and 97-100% for the newest
version. It is a flexible, curved tube that passes through the mouth, advances posterior to
the epiglottis, and terminates in the upper esophagus. The multi-use, double-lumen, silicon
LTS is designed with ventilation outlets located between an oropharyngeal and an esophageal,
low-pressure cuff. The second lumen allows for an orogastric tube to be passed through for
gastric drainage and pressure release. Patients at risk of regurgitation now have an
alternative to tracheal intubation. This device has been used in a number of patients by
anesthesiologists in Europe. There are many published scientific abstracts in the use of
the LTS. A disposable version of the LTS is now available, the LTS-D. The LTS-D offers the
same benefits as the LTS, but being disposable, it also eliminates the risk of
The ProSeal Laryngeal Mask Airway (PLMA, LMA North America Inc.) is the pre-existing
double-lumen supra-glottic device that allows gastric drainage and pressure release. Its
design is based on the LMA with an added lumen. It is reusable. The ProSeal exhibits an
unsuccessful ventilation rate of 9%, and a first time insertion failure of 12.7%. Currently,
the ProSeal exhibits a 3% incidence of foldover during insertion that prevents it from
functioning properly. Due to differences in design, we postulate that the LTS-D will have a
lower incidence of foldover than the PLMA.
This clinical study has been designed to compare the ProSeal, ETC and LTS-D as to the ease
of placement and ventilation during controlled ventilation, proper positioning, the seal
pressure with each placement, the patency of the drain tube by suctioning and measuring
stomach contents, and finally, any complications with their use. Fiberoptic observations
through each device will provide information in relation to the epiglottis and the distal
opening of the device.
1. The subjects will be adult surgical candidates aged 18-80, ASA I-III, Mallampati I or
II, presenting for elective surgery who require general anesthesia in whom tracheal
intubation is not necessary.
2. Both male and female patients will be included.
- Patients will be excluded from the study if they present as Mallampati III or IV, ASA
IV-V or emergency status. Additionally, they will be excluded if they meet one of
the contraindication criteria of the LMA ProSeal including:
3. History of gastric regurgitation, heart burn, ileus or "full stomach"
4. History of low pulmonary compliance or high pulmonary resistance
5. Known history of difficult endotracheal intubation or signs suggesting the
possibility of difficult intubation
6. Pharyngeal pathology or
7. Upper airway obstruction due to laryngeal pathology.
- Additionally, they will be excluded if they meet one of the contraindication criteria
for the Combitube including:
1. Intact gag reflexes
2. Height <4 feet
3. Central airway obstruction
4. Recent ingestion of caustic substances
5. Known esophageal pathology, or
6. Known latex allergy.
- They will also be excluded if any tracheal disease is present such as tracheal
tumors, stenosis or previous tracheal surgery.