Invasive Ventilation

In an emergency, invasive ventilation is often the only way to secure the airway and maintain vital gas exchange in the lungs. It is used in acute respiratory failure, severe traumas such as burns or during surgical procedures.1 Emergency medicine and intensive care medicine without invasive ventilation are thus inconceivable.
It does involve risks, however, so non-invasive ventilation (NIV) may be a better alternative in some cases. This article explains what you need to be aware of with invasive ventilation, when it is used, and the potential complications that may arise.
Definition: What is invasive ventilation?
Invasive ventilation is a form of mechanical ventilation which may be life-saving in critical situations. It is used when there is a severe gas exchange dysfunction, when the body can no longer be supplied with adequate oxygen or expire carbon dioxide properly. Above all, however, it is used when non-invasive ventilation is unsuccessful.2
The aim of invasive ventilation is to relieve patients of the work of breathing and simultaneously to prevent serious complications such as oxygen deficiency (hypoxemia) or a rise in carbon dioxide in the blood (respiratory acidosis).3
However, its potential side-effects mean that invasive ventilation should be used for specific purposes and only for the shortest possible time. This is because breathing is supported by an endotracheal tube.
An alternative is to use a tracheal cannula that creates artificial access to the trachea (tracheostoma). This method is usually necessary for patients requiring long-term mechanical ventilation. The endotracheal tube, on the other hand, is the preferred method in acute respiratory failure.3
A specific form of invasive ventilation is high-frequency oscillatory ventilation (or HFOV for short). This administers very small tidal volumes at a simultaneously high airway pressure. The aim is to secure gas exchange, reopen collapsed areas of the lungs and to prevent ventilation-associated lung injury by increasing pressure.
However, HFOV is not recommended in the case of severe ARDS (acute respiratory distress syndrome) as per the German S3 guidelines on invasive ventilation, as there is no clinical evidence of its success in adult patients.4
Non-invasive vs. invasive ventilation
Non-invasive ventilation is an effective treatment method in respiratory failure, as it improves survival rate and reduces the risk of infection compared to invasive ventilation.5 The great advantage of NIV is that patients can continue to breathe independently. The ventilator simply provides the pressure required to support breathing.
In contrast to invasive ventilation, NIV is performed via a ventilation mask without requiring invasive intervention such as intubation or a tracheotomy. The aim is to switch any invasive ventilation to NIV as soon as possible after the patient’s condition permits it.
A further benefit of NIV is that it places less of a strain on the patient than invasive ventilation. Patients can eat and drink during the therapy. It is usually quicker to wean patients off ventilation. What is more, non-invasive ventilation generally requires less intensive nursing, making it the preferred option for home ventilation.3
However, NIV is possible only when there is spontaneous breathing. Invasive ventilation is the only option for patients with no spontaneous breathing or with severe dyspnea. You can find a comparison of both forms of ventilation in the table below.6
- Access/ interface
Non-invasive ventilation:
- Via breathing mask, hood or similar.
Invasive ventilation:
- Via endotracheal tube, tracheal cannula or supraglottic/extraglottic airway (e.g. laryngeal tube or laryngeal mask)
- Intubation or tracheotomy required
- Use
Non-invasive ventilation:
- Mild to moderate respiratory failure
- Support of spontaneous breathing
Invasive ventilation:
- Severe respiratory failure
- Lack of spontaneous breathing
- If NIV contraindicated or unsuccessful
- Advantages
Non-invasive ventilation:
- Lower risk of infection
- Shorter hospital stays
Invasive ventilation:
- Effective ventilation in the case of severe respiratory failure
- Protection against aspiration
- Disadvantages
Non-invasive ventilation:
- Less effective in more severe respiratory failure
Invasive ventilation:
- Greater risk of complications
- Longer hospital stays due to weaning (coming off the ventilator)
Indications and applications for invasive ventilation
Invasive ventilation is required if non-invasive ventilation has an inadequate effect, is not tolerated or is contraindicated. The standard treatment for acute respiratory failure is furthermore still invasive ventilation.4
The German S3 guidelines for invasive ventilation define three applications:6
- Acute respiratory failure due to gas exchange dysfunction, if NIV fails or cannot be used - in acute respiratory distress syndrome (ARDS) for example.
- Acute or incipient displacement of the airway, if the airway is blocked or at risk.
- Unconsciousness, where protection of the airway is no longer guaranteed.
A further frequent application is polytrauma, where a secured airway supply and adequate ventilation are vital for survival. In this case, invasive ventilation stabilizes the gas exchange surface in the alveoli and ensures carbon dioxide (CO₂) is exhaled effectively.
Invasive ventilation is also required in emergency anesthesia. In these cases, mechanical ventilation takes over breathing completely.1
For patients without chronic lung disease, the guide values below are indicators for the use of invasive ventilation:
- Respiratory rate > 35/min or < 7/min
- paO2 < 40-70 mmHg
- paCO2 > 50-60 mmHg
- pH < 7.3
- FEV1 < 10 ml/kg body weight ⁷
Invasive ventilation in COPD
COPD (chronic obstructive pulmonary disease) is a chronic incurable disease often associated with long weaning phases. Non-invasive ventilation is generally the preferred method for patients with COPD.
Nevertheless, there are situations in which invasive ventilation is required – such as when conservative therapy measures prove inadequate. Indicators of this may be a pH persistently below 7.25 or a deterioration in clinical state despite NIV. Invasive ventilation should also be considered if patients lapse into a coma, lose their protective reflexes or are no longer able to cough up large quantities of sticky secretions effectively.
High carbon dioxide values (paCO2) alone, however, are not a clear indication for invasive ventilation as long as acid/base values remain in balance and there are no symptoms of hypercapnia (elevated level of carbon dioxide in the blood). As a result, it is important to assess overall clinical state without referring to individual respiratory parameters.
Overall, the following applies: The right time to use invasive ventilation in COPD needs to be weighed up carefully. If COPD deteriorates acutely (exacerbation), the switch to invasive ventilation should be made neither too soon nor too late. If invasive ventilation is introduced prematurely, it increases the risk of additional complications and may considerably extend the hospital stay, as weaning COPD patients frequently involves great effort and a complex process.8 If you wait too long, there is the risk of emergency intubation, as the patient lapses into a stupor or coma.9
Potential complications in invasive ventilation
Although invasive ventilation saves lives and is essential in certain situations, it may also entail complications.
One of the most frequent complications in conjunction with invasive ventilation is ventilator-associated pneumonia (VAP). In the first 24 hours, the risk of a lung infection is around 5.5 %. After ten days, it rises to over 80 %. The risk is especially high in the first four days, when over 50 % of cases of VAP occur.10
A further risk of invasive ventilation is barotrauma, injury to the lung as a result of excessive pressure. This increases the risk of pneumothorax, where air penetrates the space between the lung and the chest wall causing the lung to collapse.11
A similar problem is volutrauma, caused by the alveoli being over-expanded. This creates shear forces which damage the surfactant, a substance preventing alveoli from collapsing. This in turn has a negative impact on lung function and gas exchange, resulting in the release of oxygen radicals and inflammatory mediators that further damage lung tissue.12
Auxiliary airway equipment for invasive ventilation
According to the German S2K guidelines, certain auxiliary equipment is required for invasive ventilation in order to secure the airway. These include the endotracheal tube, introduced into the trachea via the mouth or nose, and the tracheal cannula, which is used in the event of surgical access to the trachea. In addition, supraglottic and extraglottic airway devices (SGA/EGA) such as the laryngeal mask can be used to secure the airway if intubation proves impossible.12
Supplementary accessories include suction devices to remove secretions from the airway, HME filters, i.e. heat and moisture exchanging filters, and tube heaters to add sufficient heat and moisture to the air for breathing. This stops mucous membranes in the bronchi from drying out and secretions from thickening, both of which potentially make breathing more difficult.
WEINMANN ventilators for mobile invasive ventilation
WEINMANN MEDUMAT Standard² and MEDUVENT Standard ventilators provide reliable support for invasive ventilation in emergency situations. Both devices have:
- An intuitive user interface with clear operating symbols
- Night display for safe operation in poor light conditions
- Extensive monitoring, e.g. pressure curves and flow curves
- Visual and acoustic warning signals for maximum patient safety
MEDUVENT Standard
- One of the smallest turbine-driven ventilators in the world
- Weighs 2.1 kg
- Battery runtime of 7.5 hours
- Ideal for mobile use
- Inspiratory oxygen concentrations from 21 % to 100 %
- Suitable for severe respiratory failure
MEDUMAT Standard²
- Battery runtime of 10 hours
- Variety of ventilation modes
- Suitable for any patient weighing 3 kg or more (infants and adults)
1 https://viamedici.thieme.de/lernmodul/6772238/4915521/beatmung#_859643A5_7DAC_417B_B2EB_E02855A5EE8C
2 https://www.usz.ch/fachbereich/neonatologie/angebot/invasive-beatmung/
3 https://www.resmed.de/medizinisches-fachpersonal/beatmung/niv-therapie/mechanische-beatmung/
4 https://register.awmf.org/assets/guidelines/001-021l_S3_Invasive_Beatmung_2017-12.pdf
6 https://wieder-selbst-atmen.de/was-versteht-man-unter-einer-invasiven-beatmung/
7 Larsen, R. & Mathes, A. (2023): Beatmung. Indikation – Techniken – Krankheitsbilder [Ventilation. Indications - Techniques - Clinical Pictures]. 7th edition Berlin, Heidelberg: Springer-Verlag, p. 542.
8 Larsen, R.; Mathes, A. (2023): Beatmung. Indikation – Techniken – Krankheitsbilder [Ventilation. Indications - Techniques - Clinical Pictures]. 7th edition Berlin, Heidelberg: Springer-Verlag, p. 542f.
9 Fresenius, Heck, Zink (2014): Repetitorium Intensivmedizin [Intensive Care Medicine Tutorial]. 5th edition Berlin, Heidelberg: Springer-Verlag, p.159.
10 Fresenius, M.; Heck, M.; Zink, W. (2014): Repetitorium Intensivmedizin [Intensive Care Medicine Tutorial]. 5th edition Berlin, Heidelberg: Springer-Verlag.