Continuing Education Activity

Noninvasive positive pressure ventilation involves providing ventilatory support through the patient's upper airway using a mask or similar device, avoiding the need for endotracheal intubation. Noninvasive positive pressure ventilation minimizes complications such as ventilator-associated pneumonia and airway trauma associated with invasive methods. This form of ventilation is the standard intervention for respiratory distress in the prehospital setting. Clinicians must be aware of when noninvasive positive pressure ventilation may improve the work of breathing and oxygenation for patients with different cardiopulmonary complaints related to primary respiratory or cardiovascular complaints. Prehospital continuous airway pressure, a form of noninvasive positive pressure ventilation, improves breathing and oxygenation, reducing intubation rates and complications, and is now the standard care for acute respiratory distress.

This activity describes the indications, contraindications, and potential complications of continuous airway pressure devices in the prehospital setting. The interprofessional team is highlighted in managing patients with respiratory, cardiac, and infectious conditions. Although other illnesses may vary in presentation, the underlying physiology is essential to understanding and ensuring effective and safe noninvasive positive pressure ventilation use.

Objectives:

• Identify the indications for noninvasive positive pressure ventilation in the prehospital setting. 

• Determine the contraindications for noninvasive positive pressure ventilation compared to other forms of ventilation.

• Interpret the physiology of noninvasive positive pressure ventilation to facilitate improved respiration.

• Implement care coordination among interprofessional team members to improve outcomes for patients treated with noninvasive positive pressure ventilation.

Introduction

Noninvasive ventilation involves providing ventilatory support through the upper airway using a mask or similar device, avoiding the need for endotracheal intubation. This method minimizes complications such as ventilator-associated pneumonia and airway trauma associated with invasive methods. Noninvasive positive pressure ventilation (NIPPV) has become a standard intervention for respiratory distress in the prehospital setting.[1] During the 1950s polio epidemic, Bjorn Ibsen pioneered positive pressure ventilation, significantly reducing mortality rates.[2] By the 1980s, noninvasive forms of continuous positive airway pressure (CPAP) were adopted for obstructive sleep apnea and chronic obstructive pulmonary disease (COPD).[3][4]

Early NIPPV models used a control unit or flow generator attached to the oxygen source to produce the necessary positive pressure. Newer CPAP devices deliver a specific amount of pressure by either adjusting a control valve or the amount of flow supplied to produce the necessary positive end-expiratory pressure (PEEP). These newer models have all the necessary parts integrated into the device, costing much less compared to the original devices. Newer devices continue to decrease costs and improve simplicity.

Using CPAP in the prehospital setting gained traction in the late 1990s as the primary form of NIPPV and an alternative to endotracheal intubation or supraglottic devices. CPAP is the most commonly used NIPPV modality in the prehospital setting and helps improve the work of breathing and oxygenation for patients with different cardiopulmonary complaints. The use of prehospital NIPPV has reduced rates of intubation and complications such as hypotension, hypoxia, and cardiac arrest.[5][6] Over the past several years, this type of ventilation has become the standard of care for patients with acute respiratory distress in the prehospital setting. A meta-analysis performed by Goodacre et al shows a reduction in mortality and intubation rates compared to standard care.[7]

Anatomy and Physiology

NIPPV improves pulmonary function by enhancing lung compliance, recruiting and stabilizing alveoli, and reducing the work of breathing. NIPPV functions by applying PEEP and inspiratory positive airway pressure (IPAP). PEEP helps overcome intrinsic PEEP in conditions such as COPD, preventing alveolar collapse during exhalation and promoting better gas exchange.[8] With each breath, the negative intrathoracic pressure causes the alveoli and distal pulmonary structures to collapse. Still, in patients with COPD or pulmonary fibrosis, an abnormal residual pressure occurs due to air trapping, called auto-PEEP. CPAP applies constant pressure throughout the ventilation cycle, ultimately preventing the alveoli from collapsing entirely during exhalation.

Improved gas exchange also improves edema and recruitment.[9] This positive pressure reduces the surface tension on the walls of the alveoli by increasing the intrathoracic pressure, which helps to reduce the work of breathing. Similarly, an increase in alveolar surface area increases gas exchange. The increased intrathoracic pressure reduces preload and promotes a fluid shift out of the lungs and back into the pulmonary vasculature.[10]

Indications

Individuals who breathe spontaneously throughout the entire respiratory cycle can use NIPPV. The primary function of NIPPV is to improve pulmonary compliance and alveoli aeration by recruiting and stabilizing collapsed alveoli, improving ventilation-perfusion mismatches. CPAP increases intrathoracic pressure, reducing venous return (preload), transmural pressure, and afterload. These changes ultimately allow for enhancement in cardiac function and reduce pulmonary edema. The latest American Thoracic Society/European Respiratory Journal guidelines strongly support the use of noninvasive ventilation in acute exacerbations of COPD and acute respiratory failure secondary to cardiogenic pulmonary edema.[11][12][13]

Common indications for CPAP include:

• Heart failure: NIPPV reduces the need for intubation and improves outcomes in patients with acute cardiogenic pulmonary edema by decreasing preload and afterload, alleviating pulmonary congestion.
• Chronic pulmonary diseases, including COPD and asthma: Bilevel positive airway pressure (BiPAP) reduces the work of breathing and improves gas exchange, preventing respiratory failure progression. Although used less commonly, NIPPV can benefit severe asthmatic exacerbations by reducing air trapping and improving alveolar ventilation.
• Acute bronchitis and pneumonia: In select cases, NIPPV supports patients with pneumonia by enhancing oxygenation and reducing breathing work, particularly in those with chronic lung disease.
• Blunt chest wall trauma, including flail chest: NIPPV can be used in trauma patients with respiratory distress and without contraindications such as facial fractures or aspiration risks.
• Toxic inhalation, such as chlorine
• Severe obesity: NIPPV can remove some metabolic demands by decreasing the workload required to ventilate patients with obesity hypoventilation syndrome.
• Near drownings
• Neonates with respiratory distress
• Patients with a do-not-resuscitate status secondary to advanced disease or terminal illnesses.[6][14][15]

Contraindications

Absolute contraindications for NIPPV include cardiac arrest, respiratory arrest, coma, or any condition requiring immediate intubation. In addition, facial burns or trauma, active vomiting, or a fixed airway obstruction are all contraindications to NIPPV. Relative contraindications for noninvasive, positive-pressure ventilation include: 

• Poor clearance of secretions
• Depressed sensorium and lethargy
• Shock with the need for pressor support
• Ventricular dysrhythmias
• Intractable emesis
• Uncontrollable bleeding
• Status epilepticus
• Potential for upper airway obstruction 
• Anaphylaxis
• Tracheal injuries
• Maxillofacial or basilar skull fractures
• External masses compressing the airway

Equipment

Modern CPAP devices are portable and cost-effective, incorporating a flow generator and a PEEP valve to maintain PEEP. For prehospital clinicians, multiple commercial-grade devices that combine the flow generator with the face mask as a disposable product are available. Standard settings typically range from 5 to 10 cm H₂O. Patients with asthma, bronchitis, and COPD typically start with a pressure of 5 cm H₂O versus those with heart failure, severe pneumonia, and pulmonary edema due to near-drownings at 10 cm H₂O. At these levels, the work of breathing can be reduced by as much as 60% and improve inspiratory muscle endurance by up to 95%.[16][17][18]

Personnel

Implementing NIPPV in the prehospital setting requires comprehensive training for emergency medical service (EMS) personnel, appropriate equipment, and clear protocols. Personnel must be skilled in patient selection, mask fitting, and monitoring therapy effectiveness. The scope of practice for EMS clinicians over the years has changed with the 2018 National EMS Scope of Practice Model introduced by the National Highway Traffic Safety Administration, which further delineates the roles of prehospital clinicians. The original 2007 Practice Model for EMS clinicians had CPAP/BiPAP as a paramedic skill. Since the release of the 2018 National EMS Scope of Practice Model, EMT-Basics are now being trained in using CPAP in patient care. In many states, an EMT-B can use a CPAP device with appropriate training and approval from their medical director.[19] EMS clinicians should receive training in the indications, contraindications, and practical application of NIPPV, including troubleshooting common issues. Protocols should outline the criteria for initiating noninvasive ventilation, monitoring parameters, and steps for escalation of care if NIPPV fails.

Preparation

Patients who have never used an NIPPV device need education before application and may need help to ensure they do not fight the device. Full-face mask devices can induce claustrophobia in some patients. Education and coaching from clinicians are crucial for ensuring patient comfort. When treating a patient in acute respiratory distress, prehospital clinicians should assemble the NIPPV device quickly.

The device should be ensured to be attached to an adequately filled oxygen source because most devices use a large amount of oxygen. Specific manufacturers' device instructions should always be referred to.

Technique or Treatment

Before placing a CPAP mask, the patient is informed about how the mask will feel to anticipate any anxiety associated with wearing the device. The mask is then applied to the patient's face, and they are coached to take deep breaths. Care should be taken to ensure the mask is not too tight, which can cause discomfort and leaks. The head strap is applied to ensure the mask is comfortable and sealed against the patient's face. The patient is positioned in a semi-upright position to facilitate better breathing. 

• CPAP: The device is started at a lower pressure setting, around 5 cm H₂O, to allow for acclimation. Gradually, this pressure can be raised to 10 cm H₂O. Some patients may benefit from higher CPAP. Oxygen can then be titrated based on SpO₂, typically starting with 2 to 4 L/min.

• BiPAP: the patient is started on lower pressures to allow for acclimatization. Typically, an IPAP of 10 cm H₂O and an expiratory positive airway pressure of 5 cm H₂O are used. The typical range for IPAP is 10 to 20 cm H₂O, whereas expiratory positive airway pressure typically ranges from 4 to 10 cm H₂O. Oxygen flow is adjusted, starting at 2 to 4 L/min, and titrated based on SpO₂ readings.

The patient is reassessed frequently to improve their respiratory status, lung sounds, and tolerance of the device. The patient's vital signs, including respiratory rate, heart rate, blood pressure, and SpO₂, are monitored regularly. The patient's clinical response is assessed, including improvement in breathlessness, reduction in respiratory rate, and stabilization of vital signs.

Complications

Complications of NIPPV include patient discomfort, anxiety, and agitation. More severe complications may consist of pulmonary barotrauma or hypotension secondary to increased intrathoracic pressure and reduced preload. Gastric distention may result in abdominal compartment syndrome; this is most likely to occur with an IPAP greater than 20 cm H₂O.[20] Many of these problems can be alleviated using the lowest, safest setting that provides results. Hypotension can be treated with intravenous fluids.

Clinical Significance

Noninvasive positive pressure and CPAP ventilation significantly improve acute respiratory distress from several etiologies. NIPPV also decreases the rate of intubations and more invasive management, which may lead to subsequent aspiration, infections, and prolonged hospitalizations. NIPPV is the mainstay treatment for patients with heart failure and COPD. Ucgun et al demonstrated that the most important predictor of mortality in patients with COPD is invasive ventilation and complications related to mechanical ventilation; preventing invasive ventilation is essential.[12][21][22]

Recent meta-analyses and studies have demonstrated that prehospital noninvasive positive pressure ventilation (NIPPV) significantly enhances patient outcomes. Specifically, NIPPV has been shown to reduce mortality rates and decrease the necessity for intubation in patients.[7] Noninvasive ventilation, including CPAP and BiPAP, is a critical intervention for managing respiratory distress in the prehospital environment. Evidence supports the use in conditions such as heart failure, COPD, and potentially asthma and pneumonia. Effective implementation requires proper training, appropriate equipment, and well-defined protocols. Integrating NIPPV can significantly enhance patient outcomes and reduce emergency department burdens as EMS systems evolve.

Enhancing Healthcare Team Outcomes

Prehospital clinicians have been conducting research to demonstrate the efficacy of noninvasive ventilation in the prehospital setting. The research has been overwhelmingly positive, where the 2018 EMS Scope of Practice Model concludes using CPAP at the EMT level and above.

The EMS scope of practice model, along with the EMS agenda for the future, shows the value and need for prehospital clinicians to be educated to perform the skills, with most training programs being accredited by the Commission on Accreditation of Allied Health Education Programs (CAAHEP), then certified as competent with most states requiring an initial certification through the National Registry of emergency medical technicians. Most states allow prehospital clinicians to perform noninvasive ventilation as a minimum scope of practice, with medical directors credentialling the prehospital clinicians. The trend for using noninvasive ventilation in the prehospital setting has influenced emergency medicine clinicians, nurses, respiratory therapists, and hospitals to adopt a similar practice method of using noninvasive ventilation in the hospital setting. Education on noninvasive ventilation has become a collegial endeavor between prehospital and hospital clinicians.