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IMPLICATIONS: Regular use of the transtracheal catheter (TTC) both offers an opportunity for training for the difficult airway and facilitates elective endoscopic surgery. Fiberoptic guidance and exploratory puncture improve the insertion of the TTC.
Algorithms for the difficult airway often recommend the use of the transtracheal catheter (TTC), particularly for the management of the cannot-intubate-cannot-ventilate situation (15). However, many anesthesiologists do not have adequate practical experience with this technique, and the result is an unsatisfactory outcome (6,7). We therefore use the TTC as often as possible for elective endoscopic surgery in the otorhinolaryngology department and systematically use fiberoptic guidance for insertion.
We conducted an audit of 158 insertions of TTCs performed between January 1, 1998, and July 31, 2000. Ethics committee approval had been obtained. For safety reasons, the TTC was used for elective surgery only if an anesthesiologist specially trained in this technique was available. A maximum of four attempts at puncture with the TTC was allowed. Reinsertion of the steel needle into the TTC was not permitted (because of danger of perforation of the catheter). We used a 13-gauge TTC manufactured by VBM Medizintechnik (Sulz, Germany) (8). It is 70 mm long, made of radio-opaque Teflon (and therefore not inflammable), and mounted on a stainless steel needle. An Olympus P30 fiberbronchoscope (Olympus Optical AG, Schwerzenbach, Switzerland) with a video system was used to monitor the insertion procedure and the final position of the TTC. The following procedure was used. The electrocardiogram, pulse oximeter, automated blood pressure cuff, and transcutaneous measurement of PCO2 were set up. Cocaine 10% 0.25 mL was then instilled into both lower nasal canals so that the fiberbronchoscope could be inserted. General anesthesia was then induced with 0.10.2 mg fentanyl IV and 1.52.5 mg/kg propofol IV and maintained with 810 mg · kg-1 · h-1 propofol IV. A paralyzing dose of 0.6 mg/kg rocuronium IV was injected when manual positive pressure ventilation by bag and mask had been established. After the occurrence of paralysis, one anesthesiologist inserted the fiberbronchoscope into the area of the cricothyroid membrane via the nasal route. A second anesthesiologist responsible for inserting the TTC stood on the left of the patient. He or she first performed exploratory puncture with a 25-gauge cannula and immediately afterward inserted the TTC. The insertion of the 25-gauge needle (exploratory puncture) and the TTC were fiberoptically guided. Jet ventilation was not started until the TTC was correctly positioned (air/oxygen mixture, frequency = 150 per minute; AMS 1000 jet ventilator manufactured by Acutronic Medical Systems AG, Hirzel, Switzerland). The TTC remained in situ until the patient left the recovery room. The following were documented and used in the evaluation: final position of the exploratory puncture (endoscopic), final position of the TTC (endoscopic), maximum compression of the trachea during insertion of the TTC (endoscopic), contact with or damage to the pars membranacea with the tip of the TTC (endoscopic), number of attempts with the TTC, and complications. In the absence of a better method, lateral deviation from the final position of the 25-gauge cannula and the TTC was documented by estimating the angle from an imaginary midline down the anterior tracheal wall, and the category "good," "poor, left," or "poor, right" was assigned (Fig. 1). The position of the TTC was documented as either in the cricothyroid membrane or in a position distal to it. The compression of the trachea during the insertion procedure was documented as "minimal" (up to about one-quarter of the lumen), "moderate" (more than one-quarter up to about three-quarters of the lumen), or "marked" (more than three-quarters of the lumen). The minimum distance between the tip of the needle of the TTC and the mucous membrane of the pars membranacea during the procedure was classified as "clear" (no contact), "in contact," and "injured" (visible traces of bleeding). If the TTC was removed from the skin, the next attempt was documented as a new one.
In cases of elective surgery for suspected tumors, the patients were examined awake fiberoptically before anesthesia was started, to eliminate a severely compromised airway. If the airway was compromised, the TTC was inserted under local anesthesia. If fiberoptic monitoring and exploratory puncture were not possible because of very difficult conditions, an attempt was made to aspirate air instead. Free aspiration of air via the inserted TTC by using a syringe was taken to be evidence of correct positioning. Statistical evaluation of the results (cross-tabulations) was performed with the Systat® 7.0 for Windows program (SPSS, Chicago, IL); the level of significance was P < 0.05.
One-hundred-fifty-eight records from 138 patients were evaluated. The median age (range) was 59 yr (1889 yr), and the median body mass index (range) was 24 kg/m2 (1633 kg/m2). The female/male ratio was 52:106. One-hundred-fifty-five TTCs (98%) were inserted for elective surgery. Of these, 134 (85%) were successfully positioned after the first attempt. In 3 cases a TTC had to be used unexpectedly, 2 of 158 TTCs were inserted under local anesthesia, and fiberoptic guidance was not possible in 4 of 158 cases. The indications for the TTC are given in Table 1. Sixteen patients who needed TTCs again for follow-up surgery experienced no disadvantages because of the previous TTCs.
Of the 154 TTCs performed under fiberoptic guidance, 100 were inserted via the cricothyroid membrane and 54 in the region of the anterior wall of the trachea between the cricoid and the first or second tracheal ring. In the case of lateral deviation, the final position of the TTC compared with the exploratory puncture was improved (Table 2, P < 0.005). A larger number of TTCs were inserted to the left (Table 2, P < 0.01). Table 3 shows details of lateral deviation of the final position of the TTC from the midline in relation to the catheter site. The deviation was smaller if the puncture was made via the cricothyroid membrane (P < 0.001). In cases in which the puncture was inferior to the cricothyroid membrane, exploratory puncture did not significantly improve the position of the final catheter position.
The extent of the compression of the trachea was more marked distal to the cricothyroid membrane than through the membrane (Table 4, P < 0.001). Puncture via the cricothyroid membrane resulted in contact with the pars membranacea in 9% of cases and damage to it in 1% of cases. Where the site was lower, there was contact in 18% of cases and damage in 2% (no significant difference).
One major and three minor complications occurred: one case of tension pneumothorax, two cases of mediastinal emphysema with no further consequences, and a transient local infection at the puncture site, which healed with no problems within a few days.
The use of the TTC for elective surgery gives anesthesiologists an opportunity to practice this important emergency technique under controlled conditions and makes endoscopic surgical procedures safer for the patient and surgeon (911). To ensure that the catheter has been positioned correctly, the literature recommends aspiration of air with a syringe attached to the catheter (8,9,12), direct observation with a rigid optical system (10,11), and the use of a capnograph (13). Much more efficient is the monitoring of the procedure with a flexible fiberoptic system, as has already been described for percutaneous tracheostomy (14,15). In this way, it is possible to monitor and control the entire insertion procedure. Furthermore, it is of particular benefit for training. Exploratory puncture (under fiberoptic guidance) helps to prevent tangential and paratracheal errors of positioning, as well as fatal rupture of vessels and damage to structures involved in voice production, with the relatively large TTC (16). It also enables optimization of the position of the distal end of the TTC, which is necessary for the correct functioning of jet ventilation. The collapse of the trachea during the procedure represents a considerable difficulty and hampers insertion (Fig. 2). Because of the fiberoptic guidance, it was possible to reduce the pressure of puncturing as soon as the tip of the TTC appeared under the mucous membrane and prevent if from breaking abruptly through the tissue distally. Contact with or damage to the pars membranacea was therefore relatively rare and did not depend on the level of the puncture site.
The traditional recommendation to puncture via the cricothyroid membrane if possible was confirmed: the position of the TTC is better, puncture is simpler, and there is a decreased risk of injury (17). If the pars membranacea is damaged by mistake, the ring-shaped cartilaginous structures offer greater resistance (18). Use of the fiberoptic equipment requires a certain degree of experience, because insertion has to be performed in as short a time as possible under apnea and the field of vision changes constantly during the procedure. With regard to training, it is worth mentioning that a higher number of TTCs were inserted to the left. When performing surgery on the upper aerodigestive tract, a compromised airway always has to be expected. Therefore, awake intubation has to be considered (3,7). To restrict the number of TTCs inserted under local anesthesia as much as possible, the airways in all endangered patients were examined fiber- optically before the induction of anesthesia. The number of complications was comparable with that of other studies (16). Russell et al. (13) reported 12 minor complications for 90 TTCs, of which 3 were directly attributable to the catheter. Monnier et al. (11) saw one minor complication in 65 cases, and Depierraz et al. (10) saw single cases of extensive surgical emphysema, bilateral pneumothorax, and severe vagus-induced cardiovascular depression in 28 TTCs. We believe that the regular use of the TTC under fiberoptic guidance for elective surgery increases familiarity with the method and facilitates the use of the method in emergencies.
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