Artificial Respiration

Artificial respiration must be used when a person’s spontaneous breathing is inadequate or nonexistent. This is the case in the following situations:

Indications (areas of application)

  • Anesthesia
  • Respiratory/cardiovascular arrest
  • Serious chronic illness, neurologic, internal, etc. (e.g., adult respiratory distress syndrome (ARDS))
  • Severe trauma (injuries)
  • Intoxications (poisonings)

The procedures

Artificial respiration is performed by directly injecting air/breathing gas mixture/anesthetic gas mixture into the lungs. It can be performed for a short period of time; ongoing therapy is readily available (home therapy)

Air can be blown into the lungs via various methods:

  • Mouth-to-mouth ventilation/mouth-to-nose ventilation.
  • Breathing mask – respiratory mask that is placed over the mouth and nose of the affected person
  • Securing the airway by means of:
    • Endotracheal tube – called a tube for short; it is the breathing tube, a hollow plastic probe inserted into the trachea (windpipe)
    • Laryngeal mask – The so-called laryngeal mask (plastic mask) is pushed in the throat just to just above the larynx, where it is sealed with an inflatable bead of air.
    • Laryngeal tube – The laryngeal tube secures the airway by closing the esophagus with a balloon and allowing the supplied air to flow into the trachea. For this, a tube with two openings in the esophagus, which it closes, comes to lie.
    • Combitube – A double tube that lies in the trachea and esophagus and is blocked (closed) depending on its position in the esophagus. This tube is used in difficult to intubate patients (intubation: securing the airway through an endotracheal tube), because here finding the trachea often causes problems.
  • Tracheostomy (tracheotomy) – is performed during long-term ventilation, radiotherapy (radiatio; radiotherapy) in the neck area or as ultima ratio in difficult airway.

The following techniques are used:

  • Mouth-to-mouth/mouth-to-nose resuscitation – simplest form of resuscitation; performed during lay resuscitation as a breath delivery.
  • Mask ventilation (i.e., non-invasive ventilation, NIV) – ventilation via a ventilation mask placed over the mouth and nose of the victim; connected to this mask is a ventilation bag, possibly connected to an oxygen source
  • Mechanical ventilation – ventilation via a ventilator; many different ventilation techniques can be distinguished.
  • Positive pressure ventilation – the air is pumped into the lungs by a positive pressure outside the lungs.
  • Alternating pressure ventilation (iron lung) – the iron lung in which the patient is located creates a negative pressure through which there is a flow of air into the lungs

It is possible to distinguish the following techniques of mechanical ventilation:

  • Controlled (mandatory) ventilation – taking over the complete work of breathing.
    • Volume-controlled ventilation – this involves determining how much air is delivered to the lungs
    • Pressure-controlled ventilation – here the maximum pressure that should prevail in the lungs is set; the volume can vary
    • Demandatory ventilation – mixed form, where the patient’s own breathing is possible.
  • Assisted (augmented) ventilation – support for breathing too shallow or too infrequent.
    • Pressure assisted ventilation
    • Continuous positive airway pressure (CPAP) – here, pressure is built up in the ventilation system; the work of breathing is done entirely by the patient

There are a variety of special forms of ventilation, which will not be discussed in detail here. The following is to be observed in principle in artificial ventilation:

  • If the patient must be intubated, a lung-sparing ventilation is to be aimed at: as low as possible plateau pressures and a small respiratory volume.
  • Adult respiratory distress syndrome (ARDS):
    • In all stages of respiratory failure, spontaneous breathing should be maintained as long as possible.
    • High PEEP pressures ((“Positive End-Expiratory Pressure”, English : “positive end-expiratory pressure”)) should be used only in patients with severe ARDS.
    • Use of adaptive procedures in ARDS.
    • Prone positioning as an adjuvant measure

    Details on ventilation therapy see below the respective disease under “Further therapy”.

Monitoring ventilation

  • Observation of the affected person
  • Respiratory rate, respiratory volume (tidal volume), respiratory minute volume (AMV), maximal inspiratory pressure (peak pressure).
  • Oxygen saturation (sO2) – measured by pulse oximetry.
  • CO2 measurement via capnometry (measurement method to measure and monitor a patient’s exhaled air carbon dioxide (CO2) content).
  • Blood gas analysis (BGA) – determination of the gas distribution of the gases oxygen and carbon dioxide in the blood (partial pressure). In addition, pH, oxygen saturation (SaO2), standard bicarbonate (HCO3-) and base excess (BE, Base Excess) are also measured.
  • Heart rate – measured by pulse oximetry.
  • Blood pressure

Possible complications

  • Infections such as pneumonia (lung inflammation) – often occur with prolonged ventilation
  • Lung damage – especially the formation of atelectasis (collapse of alveoli); lung damage can also result from prolonged high oxygen concentration and high airway pressures.

Further notes

  • The mechanical variables of mechanical ventilation (mechanical power: product of respiratory rate, tidal volume, peak pressure, and drive pressure) are among the factors that determine mortality (death rate) in patients with respiratory insufficiency (disruption of lung gas exchange with abnormally altered blood gas levels). A dose-response relationship has been demonstrated. The mechanical power parameters described are surrogate parameters; alveolar pressure (pressure in the alveoli) is crucial for lung damage caused by mechanical ventilation.CONCLUSION: Limiting drive pressure and mechanical power probably reduces mortality in ventilated patients.