Intubation Applications

Endotracheal intubation (often shortened to intubation in the narrower sense) is the insertion of an endotracheal tube (ETT; called a tube for short; it is the breathing tube, a hollow plastic probe) into the trachea (windpipe). Intubation is required during anesthesia or else in emergency situations to secure the airway.

Indications (areas of application)

  • Aspiration hazard – risk of inhalation of stomach contents.
  • Emergency situations with unconscious persons such as cardiopulmonary resuscitation.
  • General anesthesia (intubation anesthesia (ITN))

Before intubation

  • Determine before general anesthesia whether a planned intubation might be difficult. The most important question to ask is: Has the patient experienced difficulty with the procedure before?
  • Performing the “upper lip bite test,” i.e., determining whether the patient can bite the upper lip with the lower incisors? If the patient cannot, intubation is very likely to be difficult.

The procedure

To induce anesthesia, a hypnotic (sleep aid) and a fast-acting muscle relaxant (muscle relaxant) are applied (injected) intravenously (into the vein). Once the patient is asleep, he or she is ventilated via a face mask, possibly supported by an oropharyngeal (Güdel)/nasopharyngeal (Wendl) tube. This intermediate mask ventilation prevents an excessive drop in oxygen saturation. According to one study, the feared increase in aspiration did not occur. If the patient can be ventilated well, the larynx is visualized with the help of a laryngoscope (device for viewing the larynx). Then the tube (breathing tube) can be inserted into the trachea (windpipe) under visualization. Once the tube is in place, it is sealed in the trachea with an inflatable cuff (block cuff). In a departure from the procedure shown above, in what is known as rapid sequence induction (RSI, “rapid sequence of anesthesia induction”), intermediate ventilation is not performed if the patient is not fasting, there is bleeding in the upper gastrointestinal tract (gastrointestinal tract), or gravidity (pregnancy). The aim of this form of anesthesia induction is to avoid aspiration (inhalation of stomach contents). The following procedures can be distinguished:

  • Orotracheal intubation – insertion of the tube (breathing tube) through the mouth.
  • Nasotracheal intubation – insertion of the tube through the nose.
  • Fiberoptic intubation – in this case, under local anesthesia (local anesthesia) with the help of a bronchoscope (a flexible endoscope for lung endoscopy), the tube is inserted into the trachea under endoscopic vision; after successful intubation, the tube is protected by a biting wedge, if necessary.

Other forms of ventilation

  • Mask ventilation – for bridging or short duration anesthesia.
  • Supraglottic airway devices (SGA) – their end comes to rest above the glottis; Indication: for difficult airway securing when endotracheal intubation fails.Advantage: are more often successful on the first attempt Disadvantage: airways are not protected from aspiration of gastric contents. Note: Aspiration protection is significantly inferior to the endotracheal tube. SGAs include:
    • Laryngeal masks (laryngeal masks) – for short uncomplicated procedures on fasting individuals.
    • Laryngeal tube (LT; Combitube).

Possible complications

  • Aspiration pneumonia/pneumonia (pneumonia) resulting from vomited stomach contents or other substances entering the lungs (during intubation in the emergency department) (8%)
  • Bleeding in the mouth/throat
  • Vocal cord ulcers (vocal cord ulcers)
  • Vocal cord granulomas – benign neoplasms.
  • Vocal cord damage
  • Tracheal injuries – injuries to the trachea.
  • Oral/pharyngeal injuries – including LT-associated tongue swelling.
  • Tooth damage
  • Tongue or pharyngeal (“affecting the throat (pharynx)”) swelling and glottic edema (acute swelling (edema) of the laryngeal mucosa) with prehospital use of a laryngeal tube (often due to considerable over-blocking of the cuff balloons).

Further notes

  • Endotracheal tube size ETT): Women and small men are often intubated with a tube that is too large (defined as 1 mm larger than the recommended diameter). The authors recommend the following sizes:
    • Female patients with average height (1.63 m): ETT of 6.0-6.5 mm.
    • Male patients with average height (1.77 m): ETT of 7.0-7.5 mm
  • For intubation, positioning with the head elevated improves preoxygenation (prophylactic enrichment with oxygen before induced respiratory arrest), facilitates viewing of the glottis (vocal fold apparatus with associated stellate cartilages and associated glottis), and decreases the risk of adverse events. The highest success rate for successful intubation on the first attempt was seen with the upper body elevated – at 45 degrees and above, the success rate was highest at 85.6%.
  • Patients who were intubated (“insertion of a hollow tube into the trachea”) within 15 minutes in the in-hospital setting because of cardiac arrest had a higher mortality (death rate) than the non-intubated control patients (16.4% vs. 19.4%), this was also true for a good functional outcome (= at most moderate neurological deficit) (10.6% vs. 13.6%). The group of patients who initially had a shockable rhythm showed better survival without intubation (39.2% vs 26.8%).
  • Dysphagia (dysphagia) after extubation (removal of the tube) of mechanically ventilated ICU patients affects a relevant number of patients (12, 4%) and is an independent prognostic parameter of 28- and 90-day mortality.
  • Postoperative intubation-related pharyngeal pain is significantly reduced in frequency by means of corticosteroid applied locally to the tube compared with controls without analgesia. Topical corticosteroids also performed better in terms of pharyngeal pain compared to locally applied lidocaine. With a number needed to treat of three, the results suggest a good preventive effect.
  • Supraglottic airway assist (SGA) with a laryngeal tube was as follows in patients with cardiac arrest compared with a group receiving endotracheal intubation in terms of survival at 72 hours: Laryngeal tube in 275 of 1,505 patients (18.3 percent) versus endotracheal 230 of 1,499 patients; the absolute difference of 2.9 percentage points with a 95 percent confidence interval of 0.2 to 5.6 percentage points was significant, meaning the technically inferior laryngeal tube had the better outcome.
  • According to an analysis of hospital data from a trauma center in the United States, intubation already in the emergency department appears to confer no benefit but to increase the risk of cardiac arrest 8-fold.