Anesth Analg 2003;96:432-434
© 2003 International Anesthesia Research Society
TECHNOLOGY, COMPUTING, AND SIMULATION
Endotracheal Intubation Device with a Charge Couple Device Camera
Hikaru Kohase, DDS, PhD*,
Hiroshi Sehata, DDS, PhD
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Hirohito Inada, DDS*,
Yoko Ikeda, DDS*, and
Masahiro Umino, DDS, PhD*
*Section of Anesthesiology and Clinical Physiology, Department of Oral Restitution, Division of Oral Sciences, Graduate School, Tokyo Medical and Dental University, Tokyo, Japan; and
Sehata Dental Clinic, Chiba, Japan
Address correspondence and reprint requests to Hikaru Kohase, DDS, PhD, Section of Anesthesiology and Clinical Physiology, Department of Oral Restitution, Division of Oral Sciences, Graduate School, Tokyo Medical and Dental University 1-5-45, Yushima, Bunkyou-ku, Tokyo, Japan, 113-8549. Address e-mail to hkohase.anph{at}tmd.ac.jp
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Abstract
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We developed an orotracheal intubation device equipped with a charge couple device (CCD) camera, providing a wide field of vision. We used this device to perform endotracheal intubations in 62 anesthetized patients undergoing dental treatment and oral surgery. The time required to perform an endotracheal intubation with this system was examined. The use of this system is described below. The wand with the CCD camera was inserted into the oropharyngeal cavity. The oropharynx, including the epiglottis and glottis, could be visualized on the monitor screen. The tube introducer was inserted into the trachea through the vocal cords via the side tube of the wand. The wand with the CCD camera was withdrawn, leaving the tube introducer in the trachea. The endotracheal tube was then inserted into the trachea by using the tube introducer as a guide. The time required for the procedure was determined. The mean total time for the procedure was 41.2 s (maximum, 155 s; minimum, 14 s). There were no significant differences in this procedure when the patients were grouped according to the Cormack and Lehane classification. There was no failure to intubate using this system. Because the device can extensively visualize not only the larynx, glottis, and vocal cords, but also the movement of the tube introducer, on the monitor screen via the CCD camera, endotracheal intubation can be easily performed while the vocal cords are visualized on the monitor screen.
IMPLICATIONS: We developed an orotracheal intubation device equipped with a charge couple device (CCD) camera, providing a wide field of vision. We used this device to perform endotracheal intubations in 62 anesthetized patients undergoing dental treatment and oral surgery. Endotracheal intubation can be easily performed with this device.
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Introduction
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Fiberoptic endotracheal intubation has been used for micrognathia, mandibular defects, temporomandibular joint ankylosis, and mandibular or maxillary fractures in the dental region, as well as for difficult airways of any etiology. Most fiberoptic endotracheal intubation procedures are performed through a nasal or oral route while the patient is awake because it is difficult to maintain an open airway when the patient is anesthetized (1,2). Although fiberoptic intubation can visualize the oropharynx and hypopharynx, the positioning of the fiberscope’s tip is sometimes difficult because of the narrow field of vision.
We developed an orotracheal intubation device equipped with a charge couple device (CCD) camera, providing a wide field of vision. In this study, we used this device to perform endotracheal intubations in anesthetized patients undergoing dental treatment and oral surgery. The time required to perform endotracheal intubation with this system was examined.
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Methods
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The system consists of a wand with a CCD camera (ultra-small CCD camera [GA-MCA1; Tunami Sound Co., Tokyo, Japan]), a light source (8 V), an acrylic resin side tube (inner diameter, 3.5 mm; outer diameter, 4.0 mm), a 3.5-mm-diameter tube introducer, a battery case, a 3.5-mm aluminum rod for supporting the wand, and a display monitor (Fig. 1). The specifications of the CCD camera are as follows: 512 x 492 pixels, automatic exposure (electronic shutter 1/60 to 1/100 s), 12-V (15-W) electricity source, F2.6 lens, f3.9 mm, 98° view angle.
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Figure 1. Endotracheal intubation system device with a charge-coupled device (CCD) camera. Wand with a CCD camera: a, Micro camera; b, acrylic resin tube as side hole of wand (inner diameter, 3.5 mm; outer diameter, 4.0 mm); c, light.
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The use of this system is described below.
- Step 1: the wand with the CCD camera was inserted into the oropharyngeal cavity with the patient’s mouth opened wide. The tongue may be swept to the left and up by the laryngoscope’s blade (Fig. 2-1).
- Step 2: the oropharynx, including the epiglottis and glottis, can be visualized on the monitor screen (Fig. 2-2). The tube introducer was inserted into the trachea through the vocal cord via the side tube of the wand (Fig. 2-3).
- Step 3: the wand with the CCD camera was withdrawn, leaving the tube introducer in the trachea.
- Step 4: the tube introducer was inserted into the endotracheal tube, with care to maintain the position of the tube-introducer tip. The endotracheal tube was then inserted into the trachea, by using the tube introducer as a guide (Fig. 2-4).
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Figure 2. The procedure for intubation. 1, Insertion of the wand into the oropharyngeal space. 2 and 3, Visualization of the glottis on the monitor screen and insertion of the tube introducer into the trachea via the side hole of the wand. 4, Insertion of the endotracheal tube into the trachea by using the tube introducer as a guide.
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Sixty-two patients (52 female and 10 male patients; age, 9–65 yr; weight, 23–78 kg; ASA physical status I–II) undergoing general anesthesia for dental treatment and oral surgery and requiring endotracheal intubation were enrolled in this study. The study was performed after we obtained the approval of our university’s ethical committee and written, informed consent from all patients or their guardians after detailed explanation of the study.
Atropine sulfate (0.5 mg) was injected IM 30 min before the induction of anesthesia. After the IV administration of 5 mg/kg of thiopental and 0.2 mg/kg of vecuronium bromide, anesthesia was maintained with 7 L/min of oxygen and 3% sevoflurane. Artificial ventilation was performed, and the patient’s laryngeal space was evaluated according to the Cormack and Lehane classification (3) by two anesthesiologists with sufficient experience. Pulse oximetry (SpO2), end-tidal CO2 (ETCO2), noninvasive blood pressure (BP), and electrocardiogram were monitored throughout the anesthesia.
The time required from the insertion of the device into the oral cavity to the completion of endotracheal intubation was determined by the anesthesiologist. In addition, the time between the insertion of the device into the oral cavity and the insertion of the tube introducer (a), the time between the insertion of the endotracheal tube along the tube introducer and the completion of the intubation procedure (b), and the total time between the insertion of the device into the oral cavity and the completion of endotracheal intubation (a + b) were also analyzed by an independent anesthesiologist not involved in the procedure. Anesthesiologists with more than 6 mo of experience were enrolled in this study.
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Results
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According to the Cormack and Lehane (3) classification system, 53 patients exhibited a Grade I laryngeal space, 7 patients had a Grade II space, and 2 patients had a Grade III space. The mean time between the insertion of the device into the oral cavity and the insertion of the tube introducer was 20.4 s (maximum, 110 s; minimum, 9 s). The mean time between the insertion of the endotracheal tube along the tube introducer and the completion of the intubation procedure was 19.8 s (maximum, 60 s; minimum, 7 s). The mean total manipulation time between the insertion of the device into the oral cavity and the completion of the endotracheal intubation was 41.2 s (maximum, 155 s; minimum, 14 s). There were no significant differences in the mean total time for the procedure when the patients were grouped according to their Cormack and Lehane classification. A decreased SpO2 and an increased ETCO2 were not observed during the procedure in any of the patients. Abnormal electrocardiogram findings, including arrhythmia, conduction disturbances, ischemic changes, abnormal BP changes, and severe heart rate changes, were not observed. There was no failure to intubate with this system.
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Discussion
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Because the device described in this report can extensively visualize not only the larynx, glottis, and vocal cords, but also the movement of the tube introducer, on the monitor screen via the CCD camera, the tube introducer can be easily inserted into the trachea while the vocal cords are visualized on the monitor screen. In addition, the CCD camera offers a very clear view, enabling the structural condition of the larynx, glottis, and vocal cords to be examined in detail. Because of the relative far positioning of the CCD camera from the target, the device can provide a wide field of vision during the maneuver. In the case of fiberscopes and stylet scopes (4,5), extensive visualization of the larynx and glottis cannot be obtained because of the relatively small field of vision of these scopes. Consequently, inspection of the larynx, glottis, and vocal cords is sometimes difficult during a fiberoptic endotracheal intubation procedure, especially when the anesthesiologist is unfamiliar with this procedure (6,7).
In this study, the time needed for endotracheal intubation with our device was 41.2 seconds. Because we did not have a control group, our new system was compared with other systems (4,8). The intubation times with our system were comparable to those required with fiberoptic and stylet scope intubation (4,8). There were no hypoxia, hypercapnia, or severe hemodynamic changes despite the apnea that occurred during the use of our device. This device is very useful for endotracheal intubation when the patient is apneic because the intubation can be completed within a short time. Hemodynamic reflexes tend to occur during a directly visualized endotracheal intubation procedure with a laryngoscope because of the pressure on the oropharynx; this occasionally results in arrhythmia, tachycardia, bradycardia, or an increased BP. Because pressure on the larynx and pharynx is avoided when our device is used, there are no abnormal hemodynamic changes. Moreover, because instructors can confirm the position of the tube introducer on the monitor screen, they can advise the anesthesiologist performing the procedure. The system is also useful for training less experienced anesthesiologists. Although we did not use the device in patients with morphological abnormalities or disorders of the oral cavity, tongue, pharynx, or larynx in this study, we intend to use the device in these patients in the future.
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References
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Accepted for publication October 10, 2002.
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Abstract
Introduction
