Chapter 18 Blind Digital Intubation
Although it was probably first described by Herholdt and Rafn in 1796 for the management of drowning victims,1 blind digital orotracheal intubation did not receive much attention in the medical literature until its revival in emergency medicine and prehospital care by Stewart in the mid-1980s.2,3 Notable publications over the years have portrayed the technique as an acceptable, if not preferable, alternative to standard laryngoscopic endotracheal intubation, particularly when the standard technique is contraindicated, has failed, or is not possible because of a lack of equipment.
In 1880, Macewen described the technique utilizing a curved metal tube in awake patients,4 and Sykes5 recommended routine use of the digital technique in anesthetic practice in the 1930s. Siddall and Lanham relegated the technique to last-ditch efforts following the failure of conventional intubation methods.3,6,7 The technique has been described in neonatal resuscitation and as an adjunct in blind nasotracheal intubation.8–10
Currently, there is widespread variation in awareness, expertise, and application of the technique in anesthesia, emergency medicine,11,12 and prehospital care. Although advances in airway management equipment and expertise have made obsolete the routine use of blind digital orotracheal intubation, it remains a valuable skill in some situations, especially in the emergency setting or under circumstances in which the anesthesiologist cannot be positioned at the head of the patient,3 rendering laryngoscopic intubation impossible.
The use of the digital technique is neither aesthetically pleasing, easily accomplished, nor entirely safe. Placing the fingers far enough down a patient’s throat to elevate the epiglottis and guide an endotracheal tube (ETT) into the trachea has implications related to selection of patients and the manual dexterity and anatomic features of the anesthesiologist.
The technique has received some popularity in the prehospital care environment, where difficult positioning of the patient, poor lighting conditions, disrupted anatomy, potential cervical spine instability, and unknown status regarding infectious disease are the norm. Digital intubation is ordinarily used when other maneuvers have failed or are likely to fail and when alternative equipment is unavailable or not functional.
Successful digital intubation demands that the patient be unconscious, both for the patient to tolerate the intense oropharyngeal stimulus and to prevent bite injuries to the anesthesiologist. Neuromuscular blockade facilitates the technique, although it is relatively contraindicated in patients with anatomically difficult or disrupted airways. Digital intubation may be indicated in the following scenarios:
4. In the presence of potential or actual cervical spine instability when the anesthesiologist selects the digital technique on the basis of the risk-benefit analysis. Although there is no evidence to suggest that the use of digital intubation alters the neurologic outcome of a patient, there may be less cervical spine motion during intubation with the digital technique compared with conventional laryngoscopic orotracheal intubation without in-line stabilization.
5. When adequate visualization of the airway to allow conventional intubation is not possible because of the presence of copious secretions, blood, or vomitus in the oropharynx or traumatic disruption of the upper airway anatomy.
As with any intubation technique, preparation involves assembling the necessary equipment and personnel, including emergency drugs and adequate suction, to optimize success and preserve ventilation and oxygenation. An appropriately sized ETT is selected. The use of a stiff but malleable stylet improves maneuverability during the intubation. Lubrication of the stylet with a water-soluble lubricant ensures easy retraction after the tip of the ETT is placed in the glottic opening. The stylet is then inserted into the ETT so that the distal end of the stylet is at the level of the Murphy eye. With the stylet in place, the distal half of the styletted ETT unit (SETT) is bent into a “U” configuration (Fig. 18-1). The proximal half of the SETT is then bent approximately 90 degrees toward the dominant side of the ETT to allow manipulation of the SETT by the dominant hand during intubation (Figs. 18-2 and 18-3). The degree of bend should be individualized and is dependent on the anesthesiologist’s experience.
Figure 18-3 Final configuration of the styletted endotracheal tube (SETT) allows improved control of the ETT with both hands. During the intubation, the index finger of the dominant hand can help advance the ETT while the index and middle fingers of the nondominant hand guide the tip of the ETT into the glottis.
The tip of the ETT should be well lubricated with a water-soluble lubricant. In the uncommon event that the intubation is performed in an awake patient, especially an uncooperative patient, a bite block should be placed between the patient’s molars on one side to minimize the risk of injury to the anesthesiologist’s fingers.
The patient should be supine with the head in a slight sniffing position, as for laryngoscopic intubation. The anesthesiologist stands (or kneels if the patient is on the ground) beside the patient so that his or her nondominant side is closest to the patient. An assistant can help to facilitate the intubating procedure.
Pulling the tongue forward by an assistant facilitates palpation of the epiglottis, thus improving the success rate for digital intubation. The patient’s mouth is opened, and the tongue is grasped gently by the assistant with a piece of gauze (Fig. 18-4). Traction on the tongue moves the epiglottis slightly cephalad, enhancing its palpability and facilitating placement of the tip of the ETT into the glottic opening. The anesthesiologist then inserts the index and middle fingers of the nondominant hand into the oral cavity and slides the palm down along the surface of the tongue (Fig. 18-5). The tip of the middle finger touches the tip of the epiglottis, which is then directed anteriorly (Fig. 18-6). The ease of palpating and lifting the epiglottis depends on the length of the anesthesiologist’s fingers, the height of the patient, the anatomy of the oropharynx, and the presence or absence of teeth.
Figure 18-4 The tongue is grasped gently by an assistant with a piece of gauze. Traction on the tongue moves the epiglottis slightly cephalad, enhancing its palpability and facilitating the placement of the tip of the endotracheal tube into the glottic opening. An upward (cephalad) and backward (posterior) pressure applied anteriorly to the larynx by the assistant may help the anesthesiologist to feel the epiglottis during digital intubation.