Continuous Positive Airway Pressure (CPAP)
CPAP ventilation is a life-saving form of ventilation essential in the emergency medical services. In the case of acute breathing difficulties, it ensures a reliable oxygen supply and alleviates patients’ respiratory distress. There is evidence that CPAP ventilation has positive treatment results in a number of clinical pictures, making it a wide-ranging, indispensable aid in emergency medicine.
Innovative ventilators from WEINMANN equip you perfectly to act quickly and effectively in any emergency situation. Read this article to find out more about how CPAP therapy works, its many benefits and its significance for the emergency medical services.
CPAP: Definition
CPAP stands for Continuous Positive Airway Pressure and is a form of ventilation which maintains a continuous positive airway pressure. This positive end-expiratory pressure (PEEP) makes breathing easier, improves oxygenation, and reduces the tendency of the alveoli to collapse.
CPAP ventilation is a form of assisted ventilation which supports spontaneous breathing. The ventilator itself does not specify a respiratory rate of its own, so adequate spontaneous breathing by patients is a key prerequisite for this application.
Indications for CPAP ventilation in emergency medicine
CPAP ventilation has become established as a versatile and effective therapy option in emergency medicine. For example, it can be used in ventilation disorders such as chronic obstructive pulmonary disease (COPD) and especially in acute exacerbation of COPD (AECOPD). In cases like this, CPAP ventilation reduces the work of breathing and provides patient relief.
CPAP therapy is furthermore indicated in oxygenation disorders/inadequate spontaneous breathing, as in the case of acute post-operative respiratory insufficiency, pulmonary contusion, acute lung injury, atelectases, cardiogenic pulmonary edema, and pneumonia.1 This also includes the kind of airway collapse which may occur in adults and children with obstructive sleep apnea (OSA).
In the event of carbon monoxide poisoning, the 2021 guidelines of the Deutsche Interdisziplinäre Vereinigung für Intensiv- und Notfallmedizin e. V. [DIVI - German Interdisciplinary Union for Intensive Care and Emergency Medicine]2 recommend starting primary care with mask CPAP. This prevents symptoms such as confusion, nausea, and severe acidosis, whilst simultaneously reducing the risk of acute circulatory collapse. CPAP ventilation at 5 to 12 mbar significantly reduces the half-life of carbon monoxide hemoglobin (CO-Hb) and thus improves the prognosis of affected patients.3
In premature infants with Infant Respiratory Distress Syndrome (IRDS), CPAP can help alleviate respiratory distress due to insufficiently developed lungs and a lack of surfactant. A study by Kamper and Ringsted illustrates the efficacy of CPAP therapy in IRDS.4
CPAP ventilation furthermore supports oxygen supply in infants with acute infections such as bronchiolitis or pneumonia as well as with a collapsed airway (e.g. tracheomalacia).
Contra-indications
CPAP ventilation is contra-indicated if there is no spontaneous breathing. If respiratory drive is weak, invasive ventilation or alternative non-invasive forms of ventilation such as BIPAP should be preferred, as these provide greater support with expiration compared to CPAP therapy.
CPAP ventilation is furthermore contra-indicated if patients are anxious, unco-operative or refuse this form of ventilation.
CPAP ventilation is likewise unsuitable for certain medical conditions which may jeopardize the safety of ventilation, cause an existing clinical picture to deteriorate or interfere with the healing process. These conditions include:
- Limited consciousness and an inability to keep the airway clear independently
- Unstable cardiovascular function or apnea
- Heavy secretion in the airway
- Severe nausea and vomiting
- Injuries or burns to the face making it difficult to fit the mask
- Recent operations to the face, esophagus or stomach
Benefits of CPAP ventilation
A key benefit of CPAP ventilation is the reduction in work of breathing. Continuous airway pressure helps maintain functional residual capacity (FRC). This reduces the tendency of the alveoli and small airways to collapse, which is particularly relevant to infants. This furthermore recruits the atelectatic areas of the lungs and reduces intrapulmonary right-to-left shunt, leading to improved oxygenation and a better ratio of ventilation to perfusion.5
Evidence of the efficacy of CPAP therapy in emergency response is provided by numerous studies and is not in dispute. It has been possible to prove, for example, that the use of CPAP in emergency medical sessions reduces both mortality rate and the need for intubation.6 The use of NIV-CPAP for acute respiratory failure furthermore leads to significant stabilization of vital signs, regardless of the duration of therapy.7
Risks
However, CPAP ventilation may also be associated with side effects. For example, patients may experience a dry mouth and dry mucous membranes of the nose if the air is not adequately humidified. A poorly-fitting CPAP mask may allow air to escape, possibly resulting in irritated skin and eyes. At too high a pressure, air may be swallowed and reach the stomach, casuing patients to feel full or bloated.8
Respiratory acidosis can also occur as a long-term consequence, as the continuous pressure of CPAP therapy can obstruct expiration. As a result, carbon dioxide is not removed from the circulation as effectively and the pH of the blood rises.9
In rare cases, lung problems may be caused by CPAP - such as overexpansion of the lung due to continuously excessive pressure.10 In infants, CPAP ventilation has also been associated with air leak syndrome.11
Whether CPAP ventilation ultimately involves the drawbacks quoted depends on the quality of ventilation. Most of these problems can be avoided by setting pressure correctly and positioning the mask properly. Risks can be largely eliminated by an induction course led by trained professionals and by suitable ventilators.
Forms of CPAP
Pure CPAP ventilation continuously delivers a positive inspiratory flow, regardless of the patient’s spontaneous breathing. This mode can keep the airway open and improve oxygenation, although the continuous counterpressure may make the work of breathing harder. CPAP ventilation is accordingly often used in combination with Assisted Spontaneous Breathing (ASB) or Pressure Support Ventilation (PSV).
CPAP with pressure support (CPAP + ASB/CPAP + PSV)
A further development of CPAP ventilation are ventilation modes with pressure support, also known as CPAP + ASB or CPAP + PSV. With these modes, the device detects the patient’s inspiratory efforts via a trigger and synchronizes delivery of pressure support with this effort, significantly reducing the work of breathing.
In the event of inadequate spontaneous breathing or apnea, it is also possible to activate mechanical apnea ventilation. This function ensures that if breathing fails, the ventilator automatically switches to a supporting or controlled ventilation mode to guarantee breathing.
Non-invasive CPAP ventilation (NIV-CPAP)
Non-invasive CPAP ventilation (NIV-CPAP) is performed via a mask. It is of great significance in emergency medical services, in particular, and is used for acute respiratory distress.
Invasive CPAP ventilation
Invasive CPAP ventilation is effected in hospital via a tracheal tube or cannula and is used in particular for successful extubation. By supporting spontaneous breathing, CPAP ventilation can facilitate the transition or weaning process from mechanical ventilation to spontaneous breathing.12
CPAP accessories
CPAP ventilation requires a large number of accessory parts for effective, safe ventilation:
- CPAP ventilator: The ventilator generates a continuous air pressure.
- CPAP mask: Various types of mask are available, including nasal cannulas, full-face masks, and face masks.
- Head strap: The head strap ensures that the mask does not slip and prevents air leaks.
- Anti-asphyxia valve: This valve allows air to be breathed out and prevents carbon dioxide accumulating.
- Ventilation hose: The hose connects the ventilator to the mask and directs the air flow.
- Pressure measuring tube: The pressure measuring tube is likewise connected to the device and transmits the pressure values at the patient valve.
CPAP therapy with WEINMANN
WEINMANN supports CPAP ventilation and ensures safe and reliable use in an emergency. The MEDUMAT Standard² and MEDUVENT Standard ventilators give you powerful solutions for CPAP ventilation in emergency medical services.
With a battery runtime of 10 hours and a weight of just 2.5 kg, MEDUMAT Standard² is an ideal companion in every one of your sessions. It is suitable for patients weighing 3 kg or more and provides clear monitoring by means of flow measurement and CO₂ measurement. CPAP ventilation can be combined with optional pressure support.
MEDUVENT Standard is a lightweight, turbine-driven emergency ventilator with a low weight of 2.1 kg and a volume capacity of 3.5 l. Its battery runtime of up to 7.5 h and the option of administering oxygen concentrations from 21% to 100% mean the device can provide a reliable oxygen supply at all times - independently of external gas and power sources.
WEINMANN furthermore supplies a comfortable NIV premium mask especially suitable for NIV CPAP treatment. It is securely fixed in position with retaining straps and head straps, thus guaranteeing leaktight, effective therapy. The color-coded sizes also allow the correct mask to be selected quickly in an emergency.
With ventilators and accessories from WEINMANN, we support you to complete your emergency sessions safely and successfully and to provide patients with the best possible care.
1 Larsen, R., Ziegenfuß, T. (2017). CPAP – Spontanatmung bei kontinuierlichem positivem Atemwegsdruck [CPAP - spontaneous breathing with continuous positive airway pressure]. In: Pocket Guide Beatmung [Pocket Guide to Ventilation]. Springer, Berlin, Heidelberg. doi.org/10.1007/978-3-662-53728-2_11
2https://cprguidelines.eu/guidelines-2021
4 Kamper J, Ringsted C. Early treatment of idiopathic respiratory distress syndrome using binasal continuous positive airway pressure. Acta Paediatr Scand. 1990 Jun-Jul;79(6-7):581-6. doi: 10.1111/j.1651-2227.1990.tb11520.x. PMID: 2201166.
5 https://www.ncbi.nlm.nih.gov/books/NBK482178/
6 Larsen, R., Ziegenfuß, T. (2017). CPAP – Spontanatmung bei kontinuierlichem positivem Atemwegsdruck [CPAP - spontaneous breathing with continuous positive airway pressure]. In: Pocket Guide Beatmung [Pocket Guide to Ventilation]. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-53728-2_11
7 Hensel M, Strunden MS, Tank S, Gagelmann N, Wirtz S, Kerner T. Prehospital non-invasive ventilation in acute respiratory failure is justified even if the distance to hospital is short. Am J Emerg Med. 2019 Apr;37(4):651-656. doi: 10.1016/j.ajem.2018.07.001. Epub 2018 Jul 2. PMID: 30068489.
8 https://www.netdoktor.de/therapien/cpap/
9 https://schlafapnoe-heilen.de/2022/02/nebenwirkungen-und-risiken-der-cpap-therapie/
10https://kardena.de/blogs/news/schlafapnoe-geraet-nicht-benutzt-moegliche-probleme
11 Hishikawa K, Goishi K, Fujiwara T, Kaneshige M, Ito Y, Sago H. Pulmonary air leak associated with CPAP at term birth resuscitation. Arch Dis Child Fetal Neonatal Ed. 2015 Sep;100(5):F382-7. doi: 10.1136/archdischild-2014-307891. Epub 2015 Apr 8. PMID: 25854822.