Airway management

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The terms airway management , airway safety or airway management are used in medicine to describe all measures and knowledge that serve to secure an airway for spontaneous breathing or external ventilation so that enough oxygen reaches the lungs for sufficient gas exchange while a Obstruction through the tongue or the inhalation ( aspiration ) of blood, vomit or foreign bodies is prevented.

Airway management is always necessary if the respiratory function is threateningly disturbed by an accident or illness or if the patient's breathing is artificially ( iatrogenic ) restricted by sedation or anesthesia . In this respect, airway management is part of emergency medicine , anesthesia and intensive care medicine .

Methods

Serve to secure the airways

Storage measures

The stable side position serves as a life-saving immediate measure for the layperson to avoid obstructions of the airways through the tongue or the aspiration of vomit.

During medical measures to secure the airway, the patient is positioned on his back.

Aids to keep the airways clear

(See also manual mask ventilation and supraglottic airway aids as alternatives )

Manual mask ventilation

Bag-mask ventilation

Manual mask ventilation is indicated in anesthesia when ventilation is only of short duration, for example for short anesthesia or to bridge the time until the actual intubation for longer anesthesia. In emergency medicine, it is used to supply the patient with oxygen without adequate breathing until further securing the airway, such as endotracheal intubation, can take place. Mask ventilation is usually carried out with a ventilation bag and a ventilation mask ; as an immediate measure, oxygen can be supplied by donating breathing . Ventilation using a ventilation mask with excessively high pressure carries the risk of aspiration of gastric juice squeezed out of the stomach.

The airways of the unconscious patient are kept open (if necessary with the resulting unnecessary ventilation) either by manipulating the lower jaw or by using nasopharyngeal ( Wendl tube ) or oropharyngeal tubes ( Guedel tube ). These allow air to flow through the nose or mouth to the throat and prevent the tongue from falling back, which can also be achieved by overstretching the head and using the Esmarch handle .

Endotracheal intubation

When intubation is the insertion of a tube, a hollow probe, designated airways. The standard method of endotracheal intubation is now supplemented by a number of alternative procedures (laryngeal tube, laryngeal mask, combitubus). In the endotracheal intubation (often shortened as intubation in the narrower sense hereinafter), a is the endotracheal tube (hollow probe made of plastic) through the mouth ( orotracheal ) or nose ( nasotracheal ) between the vocal cords of the larynx ( larynx therethrough) into the windpipe ( trachea introduced). Sealing by means of a balloon ( cuff ) largely protects the airways from the ingress of secretions ( aspiration ) and enables external ventilation . Intubation is now the standard method of securing the airway . It is used in patients under general anesthesia for surgical procedures, in the event of unconsciousness or acute respiratory disorders. The introduction of the ventilation hose is only tolerated in unconsciousness or in deep sedation or anesthesia.

Non-invasive forms of ventilation offer an alternative to intubation and mechanical ventilation .

The introduction of a tube with two lumens ("double lumen tube") enables side-separated ventilation of the lungs, which is required for some procedures in thoracic surgery . This is sometimes also described as endobronchial intubation , since the tip of the tube comes to rest in a main bronchus .

Supraglottic airway devices as an alternative

Alternatives to endotracheal intubation are aids such as laryngeal mask , laryngeal tube and combitubus , which are often used when the tube is unable to be positioned correctly ( difficult intubation , see below ). They are called supraglottic airway aids because their end lies above the glottis . They are used for difficult airway management when endotracheal intubation is unsuccessful; however, their aspiration protection is clearly inferior to the endotracheal tube. In the case of laryngeal masks and laryngeal tubes, however, there are models that enable the stomach to be relieved by inserting a gastric tube through a special channel . Supraglottic airway aids are also suitable for patients who are difficult to access, for example after traffic accidents.

In the case of cardiopulmonary resuscitation, supraglottic airway devices are recommended as the first choice for rescuers without intubation expertise to enable ventilation. Endotracheal intubation should only be carried out by intubation experts as part of cardiopulmonary resuscitation and should only result in an interruption of the chest compressions for a few seconds or, ideally, with ongoing chest compressions.

Laryngeal mask with inflated bulge.

The laryngeal mask (LMA, synonym larynx mask ) is a means of keeping the airways open, which was developed by the English anesthesiologist Archibald Brain from 1981 and introduced into clinical practice. It consists of a bead-like mask that is connected to a tube. The laryngeal mask is inserted blindly into the pharynx until just before the larynx and sealed there. On the one hand, it is used to supply oxygen during general anesthesia when endotracheal intubation is not necessary (small interventions that do not involve body cavities). On the other hand, it serves as an easy-to-place instrument to secure the difficult airway.

Laryngeal tube in a plexiglass model

The laryngeal tube (LT) is a tube with two block cuffs, which, like the laryngeal mask, is placed largely blind in the throat. The lumen ends between the cuffs at the level of the larynx, so that the air that is introduced can flow into the lungs through the sealing of the cuffs up and down. The laryngeal tube is similar to the laryngeal mask in terms of application, handling and side effect profile, but it is not as gentle on the tissue. Since the sealing of the esophagus is also somewhat better, it is mostly used in emergency medicine and only rarely in routine anesthesia.

The Combitubus is a double-lumen tube that can be pushed forward blindly and either comes to rest in the esophagus (more than 90% probability) or in the windpipe. It is another alternative to endotracheal intubation and is mainly used in emergencies when the latter does not work. In this context, use is provided for in the guidelines of various specialist societies, such as in resuscitation. The Combitubus, however, does not play a role in routine clinical anesthesia. The high costs and the inability to insert a gastric tube are also disadvantageous.

Surgical airway management

If an airway management with the various existing methods is not possible ( Can not-ventilate-can not-intubate situation ), one can by the doctor coniotomy be made. This creates access to the respiratory tract at the level of the larynx by opening the membrane ( ligamentum conicum , also called ligamentum cricothyroideum ) between the cricoid and thyroid cartilage . This can be done with a puncture set or with the help of a scalpel. The cricothyrotomy is a medical, life-saving emergency measure that is used only rarely and only as a last resort , but never as a first aid measure as part of first aid.

The tracheotomy refers to a surgical procedure in which through the neck soft tissue access to the trachea is created. Indications for a tracheotomy can be, for example, the need for long-term ventilation after accidents or operations, neurological diseases with disorders of the swallowing reflex, radiation treatment of the head or neck or laryngeal paralysis. Even patients after complete removal of the larynx wear a tracheostoma.

Difficult airway management

Difficult airway management is the term used to describe the situation when the method used to keep the airway clear does not succeed. The definitions each refer to the skills of a trained anesthesiologist who has been trained with alternative means of airway management (definition of the DGAI ). A distinction is made between:

  • Difficult mask ventilation - manual bag mask ventilation is not sufficient.
  • Difficult pharyngeal airway clearance - the insertion and sealing of supraglottic airway aids does not succeed.
  • Difficult laryngoscopy - the insertion of the laryngoscope to expose the vocal folds does not succeed after several attempts (high Cormack grade ).
  • Difficult tracheal intubation - Multiple attempts at intubation are required.
  • Endotracheal intubation is not possible.
Mastering an unexpectedly difficult intubation using a video laryngoscope

In addition to the standard procedures, a number of alternative methods are used to control a “difficult airway”. If the airway is expected to be difficult to secure during planned anesthesia procedures, fiberoptic intubation is the method of choice if the patient is able to breathe spontaneously. This works under local anesthesia using a flexible endoscope , the bronchoscope, with which the vocal folds can be visualized and passed through. A tube is then inserted over the instrument. Indications of difficult airway securing (overbite, receding chin, small mouth opening, slight reclination of the head, Mallampati grade 3 or 4, etc.) are diagnosed by the anesthetist during the consultation . A reliable prognosis of difficulties in securing the airway is not possible.

An unexpected difficult airway securing arises despite a previously inconspicuous assessment, especially in the emergency situation when the patient was not known beforehand. In addition to the procedures mentioned, there are special types of laryngoscopes (according to Miller , Dörges , McCoy , Bullard etc.), video laryngoscopes, various guide rods for intubation, the intubation laryngeal mask ( Fasttrach ) through which a tube can be inserted, a rigid intubation tracheoscope (“Emergency tube”), other special aids and, as a last resort, the cricothyrotomy to ensure the patient's oxygen supply.

Algorithms for mastering difficult airway management are often available in medical facilities.

literature

  • DGAI : Airway Management. Guideline of the DGAI. In: Anesthesia and Intensive Care Medicine. 45 (2004), pp. 302-306.
  • ASA Task Force on Management of the Difficult Airway: Practice Guidelines for Management of the Difficult Airway - updated report by the ASA Task Force on Management of the Difficult Airway. In: Anesthesiology. (2003); 98, pp. 1269-1277.
  • O. Langeron, J. Amour, B. Vivien, F. Aubrun: Clinical review: management of difficult airways. In: Crit Care. 2006; 10 (6), p. 243. Review. PMID 17184555 .
  • Walied Abdulla: Interdisciplinary Intensive Care Medicine. Urban & Fischer, Munich a. a. 1999, ISBN 3-437-41410-0 , pp. 5-12.
  • A. Timmermann et al. a .: S1 guideline: Pre-hospital airway management (short version). In: Anesthesia and Intensive Care Medicine. Volume 60, 2019, pp. 316-336. DOI: 10.19224 / ai2019.316.

Remarks

  1. ↑ Safar tube: an S-shaped modified Guedel tube, one side of which can be used as an extension piece for mouth-to-tube ventilation, but in which the head should remain overstretched after insertion. Walied Abdulla (1999), p. 7.
  2. ↑ Esophageal occlusion tube: large-lumen, approximately 37 cm long, terminally closed or provided with an opening for a stomach tube with a block cuff in the lower area and holes in the upper area as well as a face mask attached to it for sealing. Walied Abdulla (1999), pp. 7-9.
  3. ↑ CD Deakin, JP Nolan, J. Soar, K. Sunde, RW Koster, GB Smith, GD Perkins: ERC guidelines for resuscitation in emergencies + rescue medicine. November 2010, Volume 13, Issue 7, pp. 559–620: Advanced resuscitation measures for adults ("advanced life support")