Biphasic Positive Airway Pressure: BIPAP Ventilation

BIPAP ventilation, also called BiLevel ventilation – is a key factor in emergency medicine. It combines spontaneous breathing and mechanical ventilation, making it extremely flexible in providing the best possible patient care in every phase. Its ability to react to differing requirements in respiratory support makes BIPAP/BiLevel ventilation an indispensable aid to the emergency medical services.

This type of ventilation is suitable for any degree of respiratory insufficiency, as in many cases, it can bypass an invasive method to provide rapid, effective support which is gentle to the lungs. This article explains everything you need to know about BIPAP ventilation and how WEINMANN supports this mode with a variety of ventilators.

Definition: BIPAP ventilation explained

BIPAP ventilation/BiLevel ventilation stands for Biphasic Positive Airway Pressure and is a timed, pressure-controlled form of ventilation which uses two different pressure levels: Inspiratory positive airway pressure (pInsp) and expiratory positive airway pressure (PEEP).This process does not specify tidal volume directly; it results from the difference in pressure between pInsp and PEEP. The greater this difference, the higher the resulting tidal volume (Vt). Minute volume can be controlled by adapting the values for pInsp and PEEP, as well as for respiratory rate (f). 

A key benefit of BIPAP ventilation is the option of spontaneous breathing in any phase of the ventilation cycle, with the valves of the ventilator remaining permanently open to allow the patient to breathe independently at any point. If he or she initiates an independent breath, the mode synchronizes with the individual respiratory rate. If there is no spontaneous breath, the device switches to pressure-controlled ventilation, the pre-set frequency ensuring ventilation is consistent.¹

In contrast to volume-controlled ventilation which administers a set tidal volume, in BIPAP ventilation, volume depends on lung compliance and on airway resistance. 

BIPAP vs. CPAP ventilation

In CPAP (Continuous Positive Airway Pressure) ventilation, pInsp and PEEP are set to the same level. A continuous pressure is applied to keep the airway open and facilitate spontaneous breathing. 

However, this form of ventilation is suitable only if patients have adequate capacity for spontaneous breathing, as CPAP does not administer controlled breaths.² BIPAP/BiLevel is more flexible in this regard, as it supports both spontaneous breathing as well as being able to administer controlled breaths if required.

Compared to CPAP ventilation, BIPAP ventilation likewise delivers a lower pressure (PEEP) during expiration. This makes it easier for patients to expel carbon dioxide and reduces the risk of hypercapnia. It also facilitates the work of breathing, as the constant pressure of CPAP makes it harder to breathe out and may cause a sensation of obstructive “counterpressure”.³

As a result, CPAP can be considered a preliminary stage of BIPAP/BiLevel. 

BIPAP-ASB ventilation 

BIPAP/BiLevel with Assisted Spontaneous Breathing (ASB) is an extension of BIPAP ventilation to facilitate patients’ spontaneous breathing by providing additional pressure support. This is generally administered at the lower pressure level and selected to be no higher than pInsp. 

Pressure support is initiated by the patient him or herself by means of his or her independent efforts to breathe. This allows BIPAP/ASB ventilation to be synchronized with the individual respiratory rate of the patient in order to ensure optimum support.⁴

Applications for BIPAP/BiLevel

A key benefit of BIPAP/BiLevel is the protective effect it has on the lungs. Pressure-controlled ventilation facilitates expiration and reduces the risk of barotrauma and volutrauma.

The flexibility of BIPAP ventilation means that some centers use it as the preferred form of ventilation for intensive care patients with respiratory insufficiency regardless of the degree of severity of the disease.⁶ At the same time, BIPAP/ASB ventilation facilitates the transition to independent breathing. Pressure support during spontaneous breathing trains the muscles required for breathing, allowing patients to be weaned off mechanical ventilation gradually.⁷

BIPAP can also be used in a variety of cardiac and pulmonary diseases which require breathing support. In patients suffering from acute respiratory distress syndrome (ARDS), in particular, mechanical ventilation can improve ventilation and reduce the work of breathing.⁸

In addition, BIPAP ventilation is indicated for obstructive sleep apnea (OSA), particularly if no success if achieved with CPAP therapy. The two pressure levels allow the mode to be adapted to suit individual requirements, thus improving both quality of sleep and oxygen supply.⁹

Ventilation parameters

BIPAP ventilation/BiLevel ventilation adapts flexibly to simulate a variety of different ventilation modes and to treat a large number of medical conditions effectively. This process allows ventilation parameters to be precisely tailored to suit specific requirements.

Setting requires a number of ventilation parameters to be taken into account:

Benefits of BIPAP ventilation/BiLevel ventilation

Compared to other invasive and non-invasive forms of ventilation, BIPAP ventilation delivers a range of benefits which may improve both the clinical outcomes and the comfort of patients:

• Closer to the natural physiology of respiration: Support of both inspiration and expiration largely simulates the natural ventilation cycle.
• Reduced risk of atelectases: The continuous positive airway pressure (PEEP) helps keep the alveoli open and thus reduce the risk of alveolar collapse.
• Maintenance of surfactant: Improved lung ventilation and function minimizes the loss of surfactant which maintains lung compliance.
• Support of spontaneous breathing: BIPAP-ASB ventilation promotes a patient’s independent breathing and thus facilitates faster weaning.
• Improved oxygenation and ventilation: The pressure levels (pInsp and PEEP) which can be set individually improve oxygenation and improve ventilation compared to conventional controlled ventilation or SIMV, especially in poorly ventilated areas of the lungs.¹¹
• Reduced requirement for sedation: As spontaneous breathing is maintained, the requirement for sedatives may be reduced; this in turn may lead to swifter recovery and fewer complications.¹²
• Reduced risk of complications: Compared to other invasive forms of ventilation, there is a significantly reduced risk of pneumothorax, barotrauma, and volutrauma.¹³

Risks of BIPAP ventilation

Although BIPAP ventilation represents an effective and comfortable therapy option, it may present certain risks to some patients. 

The effects of PEEP on the cardiovascular system may cause vascular depression under certain circumstances. The rise in intrathoracic pressure puts a strain on the heart which may lead to a reduction in cardiac output and consequently to a drop in blood pressure.

A further risk is pressures being set incorrectly; these cause excessively large breath volumes and can thus damage the lungs. 

BIPAP/BiLevel ventilators from WEINMANN

BIPAP ventilation/BiLevel ventilation is extremely effective in many cases. Patient outcome can be dramatically improved by medical professionals carefully monitoring and adapting the ventilation parameters. WEINMANN ventilators play a key role here: MEDUVENT Standard and MEDUMAT Standard² are available with the BiLevel + ASB mode as an option. 

MEDUVENT Standard is extremely compact and light, weighing just 2.1 kg and making it the perfect companion for mobile use. Assuming typical ventilation settings for adults, it has a battery runtime of 7.5 hours. Inspiratory oxygen concentrations (FiO₂) of 21% to 100% can be achieved to provide the best possible support to patients with a variety of clinical pictures.

With a battery runtime of 10 hours and numerous ventilation modes, MEDUMAT Standard², on the other hand, is a true all-rounder. The device can be used from a weight as little as 3 kg and is thus suitable for patients in any age group, making it an indispensable tool in any emergency situation.

Both emergency ventilators are furthermore intuitive and easy to operate. Ventilation can be started at any time by entering body weight, ensuring rapid ventilation in compliance with guidelines.

The devices likewise provide reliable monitoring by means of pressure and flow curves. The flow curve is of particular significance in BiLevel + ASB ventilation, as it allows respiratory effort to be detected easily and so supports the rapid adaptation of therapy.

The simple handling, intuitive operation and clear monitoring provided by WEINMANN ventilators makes them a reliable companion in any emergency situation.

¹ Lang, Hartmut (2020), Beatmung für Einsteiger, Theorie und Praxis für die Gesundheits- und Krankenpflege [Ventilation for beginners, theory and practice for healthcare]. Berlin: Springer

² Larsen R, Ziegenfuß T (2013). Beatmung [Ventilation]. 5th edition, Berlin: Springer.

³ https://schlafapnoe-heilen.de/2022/02/nebenwirkungen-und-risik

⁴ Lang, Hartmut (2020)

⁵ https://viamedici.thieme.de/lernmodul/6772238/4915521/beatmung

⁶ Larsen R, Ziegenfuß T (2017) Pocket Guide Beatmung [Pocket Guide to Ventilation]. 2nd edition Berlin: Springer

⁷https://www.jedermann-gruppe.de/bipap-beatmung/

⁸https://flexikon.doccheck.com/de/Acute_Respiratory_Distress_Syndrome

⁹https://www.resmed.de/medizinisches-fachpersonal/schlaf/behandlungsoptionen-bei-sbas/osa/

¹⁰https://de.wikipedia.org/wiki/BIPAP-Beatmung

¹¹https://www.ai-online.info/abstracts/pdf/dacAbstracts/2018/2018-02-RC303.2.pdf

¹²https://viamedici.thieme.de/lernmodul/6772238/4915521/beatmung

¹³https://viamedici.thieme.de/lernmodul/6772238/4915521/beatmung