[The transillumination technique. An alternative to conventional intubation?]

The technique of light-guided intubation is based on the principle that a source of light brought into the trachea results in clearly visible and defined transcutaneous illumination, while no illumination can be observed with the light source in the oesophagus (Fig. 1-7). The Trachlight is a reintroduced instrument for this alternative intubation technique. The essential developments are: a length-adjustable stylet with a removable internal metal wire, a brighter light source, a stable handle with tight fixation of the endotracheal tube, and a time-dependent warning device to avoid extended intubations. One hundred twenty patients (Mallampati I. ASA I-III) were included in the study (conventional intubation [group KL, n = 60]. Trachlight intubation [group TT, n = 60]. The goals of the investigation were to examine the handling, application, problems, limitations, and possible indications of the method. The recorded parameters were: number of intubation attempts: course and duration of intubation; complications; and difficulties. In 40 patients (20 in each group) the indication for invasive blood pressure measurement was given due to the surgical procedure, and circulatory parameters were recorded at defined moments during the intubation course. In group KL 55 patients were intubated in the attempt, 4 on the second, and 1 on the third (mean duration 23.6 +/- 10.4 s, range 12-60 s). Complications were: unilateral intubation (3 patients), bradycardia (2), asystole (1) and soft-tissue injury (1). Of the 60 patients in group TT. 54 were intubated successfully, the mean time needed being 29.9 +/- 14.8 s (range: 6-61 s). The remaining 6 were then intubated by the conventional method. Positive results in group TT included: easy handling and application, no injury to soft tissues or teeth, and invariably correct placement of the tube. Problems included: sufficient transillumination was achieved only after (entire) dimming of the room, insufficient control over the distal end of the tube due to an unfixed metal wire, unintentional switching off of the light while with-drawing the metal wire, difficulties in withdrawing the metal wire (too strong fixation), as well as disturbing effects of the warning device (blinking of the light 30 s after switching on). Reasons for the 6 intubation failures were introduction of the instrument into the oesophagus despite a supposed correct position, impossibility of correct placement in a patient with an extremely large goiter, and insufficiently clear transillumination in 3 extremely obese patients. The cardiovascular parameters showed no changes during laryngeal manipulation; a clear rise in heart rate and blood pressure was recorded, however, when the tube was inserted into the trachea. The cardiovascular parameters during conventional intubations were similar. The light-guided intubation technique can be regarded as a further alternative for airway management, due to the described improvement of the instrument. The indication for the technique is given in patients in whom no difficulty with intubation is expected, to avoid soft tissue damage and traumatising temporomandibular joint movements. Preclinical use may be limited due to environmental brightness. In patients with expected difficult airway management, fiberoptic intubation will remain the method of choice.