Overview of mechanical ventilation and emergency ventilators

Mechanical ventilation plays a crucial role in caring for patients in emergency situations. In extreme situations, it can maintain respiratory function and ensure an oxygen supply if the patient is unable to breathe on their own. Mechanical ventilation offers a number of advantages compared to manual ventilation and can save lives.¹

WEINMANN offers a range of emergency and transport ventilators to support mechanical ventilation in emergency situations.

Definition: What is mechanical ventilation?

Mechanical ventilation is a method where a ventilator is used to regulate and support alveolar ventilation. This guarantees a constant volume and a constant respiratory rate. Positive airway pressure ensures that the respiratory gas is transported into the lungs. 

Ventilation forms

There are two basic types of mechanical ventilation – invasive and non-invasive ventilation:

1. Invasive ventilation: Invasive ventilation involves the use of a tracheal tube or cannula that is inserted directly into the patient’s airway.
2. Non-invasive ventilation (NIV): NIV is performed without intubating the patient directly; instead, a ventilation mask covering the mouth and nose is frequently used.

Modes

Mechanical ventilation can be either volume controlled or pressure controlled:

1. Volume-controlled ventilation (IPPV, S-IPPV, SIMV): This is where a fixed tidal volume is administered, whereas the ventilation pressure fluctuates depending on the lung mechanics.
2. Pressure-controlled ventilation (PCV, aPCV, BiLevel, CCSV): Constant inspiratory pressure is delivered, but the tidal volume varies depending on lung elasticity and resistance. 

A hybrid combination of volume- and pressure-controlled ventilation (PRVC) is also possible, as are spontaneous modes (CPAP), which are used during non-invasive ventilation.

Ventilation parameters

The following are important ventilation parameters for mechanical ventilation:

Indications and applications of mechanical ventilation in emergency medicine

Mechanical ventilation is used in various areas of emergency medicine. One application is when the patient is no longer able to breathe on their own because they have been anesthetized, for example. 

Mechanical ventilation during cardiopulmonary resuscitation

In emergency situations such as cardiovascular arrest, it is important to resuscitate the person as quickly as possible and ensure an adequate oxygen supply. 

Mechanical ventilation can save lives during CPR by maintaining gas exchange in the lungs until the patient can breathe on their own again. 

Mechanical ventilation during transportation 

Mechanical ventilation is also important for transportation in a mobile intensive care unit or during patient transfer. It guarantees a continuous oxygen supply during transportation without EMS field providers having to leave their seats to administer ventilation. So mechanical ventilation also contributes to user safety.

However, ventilators are not only used for invasive ventilation – non-invasive ventilation can also be supported with various ventilation modes, for example when using CPAP therapy to treat cardiac pulmonary edema.

Advantages of ventilators

When compared directly with bag-valve-mask (BVM) ventilation, mechanical ventilation offers a number of advantages. Studies show that it is more effective than manual ventilation.² While ventilation with a bag-valve mask during CPR led to massive hypoventilation in one study, the ventilator was able to ensure more effective ventilation. 

During resuscitation, the use of a mechanical ventilator in IPPV mode is associated with a better ventilation status than the use of a bag-valve mask.

Ventilators are also advantageous when it comes to crew resource management (CRM). As a rule, two people are required for effective BVM ventilation. Ideally, one person should apply and hold the mask to the patient’s face while the other person performs the actual ventilation. However, this means that two EMS field providers are limited to one task and cannot perform any other activities.

With a ventilator, EMS field providers can perform more tasks, document them more fully and provide better care for the patient.

Providing mechanical ventilation with a ventilator frees up EMS field providers for other tasks and gives them more time to document the emergency response so that the patient can be given better and more effective care.³ This reduces the manual work required and allows medical staff to concentrate on treating the cause of the emergency. 

At first glance, the equipment for BVM ventilation appears easier to handle and less heavy, but ventilators can also be lightweight and portable. In addition, they are easy to operate and their functionality is not as dependent on precise technique as is often the case with BVM ventilation.

You can find a clear infographic on mechanical ventilation here.
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Why is manual ventilation difficult?

BVM ventilation is a method that is frequently used because it is supposedly easy to do. It involves attaching a bag, which is usually connected to an oxygen source, to a face mask via a valve. The mask is held against the patient’s face and covers both the nose and mouth. At the same time, the bag is squeezed, causing oxygen to flow through the patient’s airways. The attached valve prevents the oxygen from flowing back into the bag.

Free airways, an adequately sealed mask and the correct technique are essential for this procedure. As a rule, two people are required for this. In actual fact, this method is not easy to implement, and studies show that even experienced users have difficulties with it⁵

The main problem is the lack of a reliable method for measuring the ventilation volume or the pressure exerted on the airways. Delivery of oxygen by squeezing the bag can only be controlled to a limited extent. Without real-time feedback, there is a high risk of dangerous pressure peaks that can harm the lungs.

Excessive ventilation rates with too many breaths per minute can be another problem with BVM ventilation.¹ Hyperventilation of this kind can have negative consequences for the patient’s circulatory system.

Disadvantages and possible side effects of mechanical ventilation

Mechanical ventilation is a lifesaving measure in emergency and intensive care medicine and has several advantages over manual ventilation. However, it is also associated with risks and possible side effects. These can range from mechanical injuries to the airways caused by the insertion of a tracheal tube or cannula⁶ to ventilator-associated pneumonia (VAP) – pneumonia caused by pathogens that can enter the airways via the ventilation hose.

Other ventilator-associated lung damage can also occur due to incorrect ventilator settings. If the ventilation pressure is set too high, this can lead to overinflation of the lungs (barotrauma). The tidal volume also plays an important role: if it is too high, the lungs can be overstretched (volutrauma), whereas if it is too low, sections of the lungs can contract (atelectasis).⁷

To prevent this lung damage, it is important to have ventilators with a monitoring function for mechanical ventilation so that an alarm can be sounded immediately in the event of deviations.

Ventilators from WEINMANN

Ventilators from WEINMANN are specially designed for use in emergency situations and are suitable for both outdoor use and patient transportation. They offer the option of either invasive or non-invasive ventilation and facilitate cardiopulmonary resuscitation in accordance with the CPR guidelines thanks to the CPR and CCSV modes.

Integrated monitors allow the ventilation parameters to be monitored and provide visual and acoustic signals to warn of any deviations. This means that both hypoventilation and hyperventilation can be effectively avoided, as precise setting and monitoring functions are available.

MEDUMAT Standard² 

Emergency and transport ventilator

MEDUMAT Standard² has a color monitor that clearly and promptly displays all the important respiratory parameters. A specific mode for resuscitation (CPR) is complemented by the innovative CCSV ventilation mode, which maximizes efficiency and safety during critical situations. For anesthesiologists, the RSI mode simplifies anesthesia induction. Non-invasive ventilation is also possible with MEDUMAT Standard².

Weighing just 2.5 kg and with a battery runtime of up to 10 hours, MEDUMAT Standard² is ideal for emergency situations. 

MEDUVENT Standard 

Turbine-driven emergency ventilator

MEDUVENT Standard was specially developed for emergency response situations. With its integrated turbine, it offers ventilation from 21%-100% oxygen without any compressed gas supply required. The ventilator supports non-invasive ventilation and enables manual ventilation using the MEDUtrigger, which replaces BVM ventilation. 

Weighing just 2.1 kg and with a volume of 3.5 l, MEDUVENT Standard is one of the smallest and lightest emergency and transport ventilators in its category. Additional safety features such as the integrated alarm system warn medical personnel in critical situations. 

¹ Idris Ahamed H. (2023) Bag-Valve-Mask Ventilation and Survival from Out-of-Hospital Cardiac Arrest: A Multicenter Study.

² Hernández-Tejedor A. (2023): Ventilatory improvement with mechanical ventilator versus bag in non-traumatic out-of-hospital cardiac arrest: SYMEVECA study, phase 1; Chauhan A. et al (2023): Comparison of hemodynamic consequences of hand ventilation versus machine ventilation for transportation of post-operative pediatric cardiac patients

³ Automatic transport ventilator versus bag valve in the EMS setting: a prospective, randomized trial

⁴ Neth M et al (2020): Ventilation in Simulated Out-of-Hospital Cardiac Arrest Resuscitation Rarely Meets Guidelines

⁵ Aufderheide TP, Sigurdsson G, Pirrallo, RG, Yannopoulos D, McKnite S, Von Briesen C, Sparks CW, Conrad CJ, Provo TA, Lurie KG. Hyperventilation-induced hypotension during cardiopulmonary resuscitation. Circulation. 2004;109(16):1960-1965.

⁶ Brochard, L., et al. (2002). "Ventilation-induced lung injury." American Journal of Respiratory and Critical Care Medicine.DOI: 10.1164/rccm.2102033

⁷www.thieme-connect.de/products/ebooks/lookinside/10.1055/b-0034-20963