Modified tubeless anesthesia during endoscopy for assessment of head and neck cancers. (Original Article).

Abstract

We evaluated a modified technique of administering anesthesia without a tube and with spontaneous respiration during video-assisted tele-laryngo-tracheo-bronchoendoscopy (TLTBE). The endoscopy was performed as an alternative to rigid ventilatory bronchoscopy during screening for synchronous tumors in the tracheobronchial tree in patients who had head and neck malignancies. Thirty consecutive patients who required diagnostic panendoscopy were selected for this study. During direct-suspension laryngoscopy, anesthesia was delivered by administering intravenous bolus injections of propofol at 0.5 to 2 mg/kg every 5 to 10 minutes. A good view of the larynx, trachea, and main bronchi was obtained with a 50-cm 0[degrees] Hopkins telescope, which caused no obstruction of the airway. During laryngoscopy, arterial oxygen saturation levels, pulse rates, and blood pressures were stable in all patients. No apnea was associated with the use of propofol during any procedure, and we observed no intraoperative or postoperative complication in any patient. Video-assisted TLTBE is appropriate for patients with a grade 1 or 2 larynx, good cardiopulmonary function, and no significant airway obstruction. It is a safe and time-saving alternative to rigid ventilatory bronchoscopy for staging primary tumors and for screening for synchronous tumors in the respiratory tract.

Introduction

The original concept of field cancerization was proposed by Slaughter et al in 1953 to explain the high local recurrence rate of oral cancer. (1) This concept has also been used to explain the development of synchronous and metachronous primary tumors of the upper aerodigestive tract. The risk of developing multiple primary tumors in the head and neck region is estimated to be 3.5 to 7.4 times higher in patients who have primary index tumors (depending on the site of the primary tumor) than in patients who do not have primary index tumors. (2) Therefore, patients with primary index tumors often undergo panendoscopy for the purposes of searching for and staging synchronous primary head and neck tumors.

At some centers, surgeons still perform panendoscopy as a routine part of the diagnostic work-up, even though the use of triple-endoscopy is controversial because the incidence of synchronous primary head and neck tumors reported in literature varies widely (3 to 13%). (3) The traditional methods of panendoscopy require ventilation via endotracheal intubation during rigid laryngoscopy and esophagoscopy, and bronchoscopy requires ventilation via a rigid bronchoscope. The presence of an endotracheal tube in the upper airway during laryngoscopy compromises access to the larynx and renders examination difficult for surgeons. Tubeless anesthesia, which was originally introduced for use in microlaryngeal surgery in adults, (4,5) allows for spontaneous respiration and unobstructed access to the larynx and major airways for examination during panendoscopy.

In this article, we report our experience with a modified technique of administering tubeless anesthesia while maintaining spontaneous respiration during video-assisted tele-laryngo-tracheo-broncho-endoscopy (TLTBE). We examined the laryngotracheobronchial tree with a 50-cm, 0[degrees] rigid Hopkins telescope. Our aim was to evaluate the potential of this safe and time-saving alternative to rigid ventilatory bronchoscopy during screening for synchronous tumors in the tracheobronchial tree in carefully selected patients with head and neck malignancies.

Patients and methods

Patient selection. Our study group was made up of 30 selected patients--29 men and one woman, aged 38 to 86 years (mean: 66.5)--who had head and neck malignancies and who underwent panendoscopy as part of their diagnostic work-up in the Division of Otorhinolaryngology at the United Christian Hospital in Hong Kong between Jan. 1, 1996, and Dec. 31, 1998. Their body weight ranged from 50 to 75 kg (mean: 64.2).

Routine preoperative anesthetic assessment and hematologic screening were performed. Pulmonary function tests were performed only in patients who had a history of chronic obstructive lung disease. We excluded from consideration any patient who had trismus, neck fibrosis, a small jaw, type I or II respiratory failure (as demonstrated by blood gas analysis), and/or a history of propofol-related side effects.

Anesthesia delivery. The technique for administering anesthesia was similar to the previously described (4,5) tubeless method originally used during microlaryngeal surgery except that no sedative was given as a premedication. One or two sprays of 10% lidocaine and 1 ml of 4% cocaine were applied to one nostril for topical anesthesia and vasoconstriction. After 3 minutes of preoxygenation, an initial intravenous bolus of propofol (2 to 3mg/kg) was injected to induce anesthesia. Upon induction of sleep, a modified nasoendotracheal tube (No. 7 Nasal RAE tube) with a shortened distal end was passed through the anesthetized nostril until its tip reached the level of the soft palate. Then 100% oxygen was delivered through the nasopharyngeal airway while the patient breathed spontaneously. Intravenous fentanyl (2 [micro]g/kg) was administered as an intraoperative analgesic. Two or three sprays of 10% topical lidocaine were applied to the vocal folds to prevent laryngeal spasm. Anesthesia was maintained by administer ing an intermittent IV bolus of 0.5 to 2 mg/kg of propofol every 5 to 10 minutes, depending on the stability of the airway (determined by vocal fold movement and coughing reflex) as observed on the video monitor, the wakefulness of the patient (determined by the swallowing reflex and body movement), and the respiratory rhythm.

Following tubeless-anesthesia TLTBE, a Lindholm operating laryngoscope (Karl Storz; Tuttlingen, Germany) was left in place while an endotracheal tube was passed through its lumen and down to the trachea under direct vision. A stylet was used to straighten the tube before insertion. The laryngoscope was then removed, leaving the endotracheal tube in situ with its cuff inflated. Isoflurane was used to deepen the anesthesia, and an IV injection of the muscle relaxant suxamethonium followed. Rigid esophagoscopy was then performed to examine the esophagus.

Endoscopic technique. The patient was placed in the supine position and fitted with a head ring and shoulder support. The Lindholm laryngoscope was positioned with its tip resting on the vallecula and suspended by a Riecker-Kleinsasser laryngoscope holder that was attached to a Stange chest support fixed to the operating table. An open, uninterrupted view of the larynx allowed for a full assessment (figure 1). Additional lidocaine (1 or 2 sprays) was applied to the vocal folds when laryngospasm occurred. Excision of biopsy specimens of lesions that were identified in the upper aerodigestive tract was not performed until the end of the procedure. Prior to the telescopic examination of the tracheobronchial tree, two sprays of 10% lidocaine were applied to the trachea. The trachea, main bronchi, and orifices of the segmental bronchi were then visualized by sliding a rigid 0[degrees] Hopkins telescope (diameter: 5.5 mm; length: 50 cm [Model No. 10320A; Karl Storz]) through the Lindholm laryngoscope, past the lary ngeal inlet, and into the trachea (figure 2).

The Hopkins telescope was connected to a closed-circuit digital (CCD) camera (Karl Storz) that was connected to a video recorder and a monitor so that the entire examination could be recorded and performed while viewing the monitor. Adjusting the angle of the suspended laryngoscope helped the surgeon guide the rigid telescope so that it reached the left and right main bronchi and allowed for a good view (figure 3). A 70[degrees] Hopkins telescope (Model No. 27005B; Karl Storz) was used to reach hard-to-view areas of the larynx. Electrocardiography and measurements of continuous arterial oxygen saturation ([SaO.sub.2]), pulse rate, and blood pressure (every 5 min) were used to monitor anesthesia status. Any prolonged apneic episodes associated with desaturation ([SaO.sub.2]: <90%) were treated with assisted ventilation via a mask or a closed-circuit endotracheal tube. A conventional rigid ventilatory bronchoscope was used when examination of the tracheobronchial tree was difficult or when ventilation was insuf ficient--that is, when the [SaO.sub.2] was persistently less than 90%. Before patients were allowed to resume an oral diet, pneumomediastinum and pneumothorax were ruled out by a postoperative chest x-ray.

Results

The most common indication for panendoscopy was laryngeal carcinoma, which was present in 18 of the 30 patients (table 1). Of these 18 cases, 10 were staged as either T1 or T2 and eight were staged as either T3 or T4. Four patients who had laryngeal carcinoma had obstructive symptoms.

With respect to preoperative anesthesia status, 15 of the 30 patients were classified as type II according to criteria established by the American Society of Anesthesiologists; none was classified as type IV or higher (table 2). Intraoperatively, the laryngeal intubation status of 16 patients was classified as grade 1 according to the Cormack-Lehane classification system (6); 13 patients were classified as grade 2, and one was classified as grade 3 (table 3). No patient had type I or II respiratory failure preoperatively.

For induction of anesthesia, the amount of propofol administered ranged from 100 to 200mg (mean: 125), and the size of the maintenance dose ranged from 20 to 100mg. During telescopic examination, maintenance boluses of 50 to 100mg were injected every 5 to 10 minutes. During laryngoscopy and bronchoscopy, the dosage of propofol ranged from 150 to 800mg (mean: 345); the size of each TV bolus ranged from 20 mg to 200 mg. The amount of fentanyl administered ranged from 100 to 250 [micro]g (mean: 150). In two patients, the procedure was performed without the use of intraoperative analgesia.

The length of time required to perform video-assisted TLTBE screening of the airway ranged from 2 to 5 minutes (mean: 2.7). Patients' pulse rates ranged from 60 to 110 beats per minute (mean: 84). Their systolic and diastolic blood pressures ranged from 110 to 180 mm Hg (mean: 133) and from 60 to 100 mm Hg (mean: 79), respectively. Oxygen saturation was maintained at a level higher than 90% throughout the procedure (range: 94 to 100%). Because each procedure was performed with intermittent IV bolus injections of propofol, no apnea was noted in any patient. Coughing during the procedure was infrequent; the sensation was suppressed with additional sprays of 10% lidocaine on the laryngotracheobronchial tree and with IV injections of 25 to 50 mg of propofol.

No synchronous tumor was detected in any patient in this series. No complications related to the procedure were encountered, and no patient failed to be extubated following completion of the procedure.

Discussion

Numerous anesthetic techniques have been used during microlaryngeal surgery. Endotracheal intubation with a small tube is considered to be the easiest and safest way to secure the airway. The presence of a tube between the vocal folds invariably compromises detailed visualization of the larynx. Tubeless anesthesia allows for an excellent working environment during laryngeal inspection and surgery. Some common methods are the apneic method, (7) the jet ventilation technique, (8) and tubeless spontaneous respiration with volatile anesthetic agents. (4,9)

During the past few years, propofol has been widely used as both an induction and maintenance anesthetic during tubeless anesthesia with spontaneous respiration. (5,10,11) Propofol is an IV sedative-hypnotic that is characterized by a rapid onset of action, minimal hemodynamic disturbance, and a transient anesthetic effect, and it allows patients to breathe spontaneously. Moreover, propofol results in better jaw relaxation during laryngoscopic examination, which makes it an ideal agent for endoscopic procedures. (12) Tubeless anesthesia with propofol also allows for excellent access to the trachea and bronchi in carefully selected patients. This procedure is simple and a good alternative to conventional rigid ventilatory bronchoscopy for screening for synchronous tumors in the respiratory tract in selected patients with head and neck malignancies.

In our group of 30 patients, 18 had laryngeal cancer; in four of these 18, the tumor partially obstructed the upper airway. These patients were selected for tubeless anesthesia based on preoperative findings of an absence of hypoxemia and hypercapnia. No adverse events were observed in any of these patients during the intra- and postoperative periods. Although hypercapnia is a potential problem during tubeless anesthesia because of the difficulty in determining carbon dioxide ([CO.sub.2]) levels in an open system, we did not routinely check arterial blood gas levels during the procedure nor did we insert an endotracheal tube temporarily to monitor the [CO.sub.2] level. We based this decision on the results of studies that found that there is no significant [CO.sub.2] retention during tubeless endoscopic procedures. (5,13,14] Moreover, TLTBE screening of the lower airway takes only a few minutes to complete, and we believed that during such a short period of time, no significant [CO.sub.2] retention would deve lop in patients who were able to breathe spontaneously.

Stable and satisfactory oxygen saturation was achieved throughout the procedure, especially during the endoscopy. Adequate application of lidocaine spray to the tracheobronchial tree is essential to suppressing the sympathetic response associated with the manipulation of the telescope. (15) Unlike some other authors, (16,17) we did not encounter any hypotension associated with the use of propofol. Moreover, none of our patients experienced any apneic episodes during telescopic examination. This finding might be explained by the fact that we administered no premedication with a sedative or opioid. Our decision not to premedicate was based on the results of a study by Perrin et al, who found that drugs such as diazepam and pethidine can potentiate respiratory depression induced by propofol. (18)

Several authors have advocated the use of propofol as a maintenance anesthetic during such endoscopic procedures. (5,19) However, a continuous infusion of propofol invariably requires supplementation with IV bolus injections in order to maintain an adequate depth of anesthesia. Our experience with intermittent bolus injections titrated according to our patients' wakefulness status, airway stability, and breathing is promising and consistent with the findings of an earlier study by de Grood et al. (20) With the aid of a video monitor, the anesthetist can closely monitor the condition of the airway during the endoscopic examination and adjust the dose of propofol as required.

Video-assisted TLTBE is appropriate for patients with grade 1 or 2 larynges as determined by the Cormack-Lehane system of grading intubation. (6) Patients with trismus, stiff neck, or micrognathia are generally not suitable for this type of examination because suspension laryngoscopy is difficult in such cases. A crucial point to keep in mind during this procedure is to adjust the angle of the suspended laryngoscope so that it allows for the passage of the rigid telescope along the axis of the trachea. Otherwise, the rigid telescope might strike the anterior or posterior wall of the trachea and make further advancement into the main bronchi impossible. In addition, passing a telescope into the left main bronchus is usually more difficult because it is more horizontally positioned than the right main bronchus. We recommend that the surgeon turn the patient's head slightly to the right when attempting to approach the left main bronchus. Passage can be facilitated by adjusting the tension on the suspension of th e rigid laryngoscope so that the head can be rotated by 30[degrees] to 45[degrees]. It is also noteworthy that the diameter of the telescope is much smaller than that of the rigid ventilatory bronchoscope, and therefore there is less chance of inducing a cough reflex with the telescope.

The rigid telescope has several advantages over the flexible fiberoptic bronchoscope during TLTBE. First, it can reach difficult-to-view areas of the larynx and provide different viewing angles. Second, both the inspection of the aerodigestive tract and biopsy of any lesions can be performed safely during the same procedure. These advantages are not available with the flexible fiberoptic bronchoscope, even when it is incorporated into a laryngeal mask to provide ventilation during general anesthesia. (21) However, both the flexible fiberoptic bronchoscope and the rigid endoscope can be used to examine the segmental bronchi of the upper lobes when a suspicious lesion is noted.

The tubeless-anesthesia rigid TLTBE technique is effective in providing visualization of the lower respiratory tract. Because the procedure is performed by placing the telescope directly into the tracheobronchial tree through the suspended rigid laryngoscope, it essentially obviates the need for intubation with a wide-bore rigid ventilatory bronchoscope, which can potentially miss the airway or traumatize the upper aerodigestive tract. The connection of the telescope to a CCD camera and video monitoring provides both the surgeon and the anesthetist with an excellent view as they work closely together in performing the procedure and managing the airway. In conclusion, the modified technique of tubeless anesthesia and endoscopy described in this article is an advantageous and safe alternative to rigid ventilatory bronchoscopy for screening the tracheobronchial tree for synchronous tumors in carefully selected patients.

able 1

Indications for panendoscopy in the 30 patients in this series

Indication                            n

Laryngeal carcinoma                  18
Metastatic cervical lymphadenopathy   6
Hypopharyngeal carcinoma              2
Carcinoma of the tongue               1
Laryngeal tuberculosis                1
Parotid malignancy                    1
Squamous cell carcinoma of the        1
submandibular gland


able 2

Preoperative typing of the 30 patients according to the American Society
of Anesthesiologists' criteria

Type       n

I          7
II        15
III        8
IV to VI   0


able 3

Intraoperative grading of intubation of the larynx in the 30 patients
according to the Cormack-Lehane classification (6)

Grade   n

1      16
2      13
3       1
4       0

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From the Division of Otorhinolaryngology, Department of Surgery, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong (Dr. Ku, Dr. Tong, and Dr. van Hasselt), and the Department of Anaesthesia, United Christian Hospital, Kowloon, Hong Kong (Dr. Kwan).

Reprint requests: Prof. Charles Andrew van Hasselt, Division of Otorhinolaryngology, Department of Surgery, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, N.T., Hong Kong, SAR. Phone: [phone]; fax: [phone]; e-mail: [e-mail]