Bipap & CPAP

Description #

This unit is designed to help the students and clinically registered nurses develop a better understanding of the skills involved in respiratory assessment.

Learning Objectives #

On completion of this module, you will be able to:

1. Define CPAP and Bipap

2. State the positive effects and indications for using noninvasive ventilation.

3. State the negative effects and contraindications for using noninvasive Ventilation.

4. Identify and describe use of basic patient interfaces available for noninvasive ventilation.

5. Understand the setup procedure for initiating and discontinuing noninvasive ventilation.

This unit contains a CyberPatient module, which is a highly interactive patient-care simulator that provides a safe environment to apply your knowledge and practice your skills. This unit also has a video available under Video Resources in the resources pane that you may access and complete at your personal pace. Furthermore, each unit has a pre-test and post-test in which you are encouraged to complete to test your retention.

These resources are available to complement the pages found in the content navigation panel on the right side of the page.

Define CPAP and BiPAP®(Respironics; Murraysville, Pennsylvania) #

Ventilatory support that is delivered to the lungs without a tracheal or endotracheal airway is termed noninvasive ventilation. This support is generally delivered through a nasal or face mask in one of two modalities: CPAP or Bipap®. CPAP (Continuous Positive Airway Pressure) delivers one constant level of air pressure throughout inspiration and expiration. When the patient makes an inspiratory effort, he draws flow from the circuit and causes the pressure to drop slightly. The machine increases flow to keep the pressure at a constant level. BiPAP® (Bilevel Positive Airway Pressure) is a method of noninvasive ventilation which provides two different pressures, an IPAP (Inspiratory Positive Airway Pressure) when the patient breathes in, and a lower EPAP level (Expiratory Positive Airway Pressure) during exhalation.

State the positive effects and indications for using noninvasive ventilation. #

Noninvasive positive pressure ventilation (NPPV) can be useful for acute or chronic respiratory failure.

Positive Effects 

A constant distending pressure through CPAP or EPAP improves oxygenation by expanding collapsed alveoli and improving ventilation/perfusion relationships in the lung. This expiratory pressure also helps to splint open the soft tissues of the upper airway, preventing airway obstruction commonly seen in Obstructive Sleep Apnea. Adding an inspiratory pressure in IPAP can improve patient outcomes by reducing diaphragmatic work and providing rest to the respiratory muscles. By increasing tidal volume, it can improve gas exchange and decrease the level of carbon dioxide in order to prevent respiratory failure.

Indications in Acute Respiratory Failure 

BiPAP® has been used successfully for COPD exacerbations, asthma, congestive heart failure, acute exacerbations of restrictive lung disease, post-extubation respiratory failure, and pneumonia. Many of these patients have avoided intubation and further deterioration of their arterial blood gases. Oxygenation often improves immediately, PaCO2 may dramatically decrease, and there is often an improvement in the feeling of dyspnea and decreased heart and respiratory rate. BiPAP® is also used as an alternative to intubation and mechanical ventilation in patients with acute respiratory failure. Advantages to using a BiPAP® in this population include improved patient tolerance and less need for sedation, ease of application and removal, and avoiding some of the complications associated with endotracheal intubation.

Indications in Chronic Respiratory Failure 

Noninvasive ventilation is also used frequently in chronic respiratory failure. It is commonly used in patients with stable or slowly progressive neuromuscular syndromes, such as Muscular Dystrophy, postpolio syndrome, multiple sclerosis, or quadriplegia due to high spinal cord lesions. It is generally not appropriate for patients with rapidly progressive neuromuscular disorders causing airway compromise. It can also be used for patients with thoracic deformities, such as severe kyphoscoliosis or lordosis. The third category of chronic respiratory failure benefiting from NPPV is those with central hypoventilatory syndromes, such as obstructive sleep apnea.

State the negative effects and contraindications for using noninvasive ventilation. #

Although it can be a useful adjunct to avoiding intubation with ventilation, noninvasive ventilation shares many similar complications associated with providing positive pressure to the lungs. Overinflation of the lungs can occur with a high IPAP setting resulting in alveolar overdistention or pneumothorax. A high intrathoracic pressure can also impede venous return to the heart and may decrease cardiac output.

Avoiding the use of an endotracheal tube and associated complications is desirable in many patients, but using noninvasive means to ventilate patients can result in other hazards. Applying positive pressure to the upper airway can cause the stomach to inflate with air, increasing the risk of vomiting. Without an inflated endotracheal cuff to seal the trachea, the risk of aspiration is an ongoing and serious concern. The lack of endotracheal access also prevents effective secretion removal and can lead to retained secretions and those risks inherent. Bipap® is sometimes not considered if secretions are excessive.

The patient interface in the form of a nasal or full face mask is generally better tolerated than an endotracheal tube, but can be claustrophobic or cause pressure sores with prolonged use. Nasal congestion, dryness of the mouth and nose, epistaxis, and eye irritation are common complaints, especially with a poorly fitted mask.

There are some important contraindications to consider with noninvasive ventilation. Patients must have a consistent respiratory drive to breathe with adequate blood pressure and stable cardiac status. The loss of the ability to protect their airway would be an important contraindication. Patients must be cooperative and able to tolerate the mask and headgear and should not have copious secretions. Mask application and fitting is imperative and therefore patients with recent facial surgery, trauma, or burns may not be considered for noninvasive therapy.

Understand the setup procedure for initiating and discontinuing noninvasive ventilation. #

There are a variety of ways to deliver noninvasive ventilation. CPAP machines are usually lightweight portable units, and often incorporate humidifiers. These are the machines most often used in home care settings. Bipap® units in hospitals may be larger in size, often incorporate high and low pressure alarms, and are sometimes mounted to a rolling stand for transport between wards. Oxygen can be connected from a flowmeter and tee’d into the circuit, or in some cases the machine could be connected to a high pressure oxygen outlet and the FiO2 set internally. Oxygen flowrate or FiO2 is usually titrated to keep SpO2 >92%. CPAP is usually administered at pressures between 5 cmH20 and 15 cmH20. Levels are increased to improve oxygenation. If used for obstructive sleep apnea, pressure is titrated to keep the soft tissues of the upper airway open and therefore prevent nocturnal obstructive apnea from occurring. At most sites, Bipap® is set up as per a physician’s order. EPAP levels generally start at 5 cmH20 and are titrated to improve oxygenation. IPAP levels generally start at 8-10 cmH20 and are titrated to carbon dioxide levels or patient comfort. Begin the setup procedure by ensuring the appropriate patient interface is used and is a good fit. Ask the patient if they have had any discomfort with previous use. A respiratory therapist will be available at most sites to ensure each patient has an interface that suits their needs.

CPAP Simulation #

Cyber Patient Module

As well, he was diagnosed with pneumonia two weeks ago. Upon diagnosis, he was admitted to the respiratory ward and treated aggressively with antibiotics, fluids, and chest physiotherapy. Despite his illness, he still has a fairly effective cough, but has noticed that he feels short of breath and wakes to gasp for air at night. The RNs on night shift have noticed that he makes a loud snoring sound when sleeping. The Respirologist has ordered a trial of nocturnal Bipap therapy for Justin, after performing an overnight oximetry and a morning blood gas. The overnight oximetry showed frequent oxygen desaturations while Justin was sleeping. As well, an early morning ABG right after waking showed respiratory acidosis (high PaCO2 level). The diagnosis is chronic respiratory failure due to progressive neuromuscular weakness, affecting the respiratory muscles and diaphragm.

Current Orders:

• Follow current Bipap protocols.
• Oxygen to keep Sp02 92 %
• Tylenol 500 mg Q 6H PRN for pain.
• Moxifloxacin 400 mg PO/IV
• Fluid by pump at 60cc/hr.
• Bowel protocol

 

References #

1. Hillberg, RE and Johnson, DC. Noninvasive Ventilation NEJM 1997; 337: 1746-52 Mehta S, Hill NS. Noninvasive ventilation.
2. Am J Respir Crit Care Med 2001; 163:540-577 Noninvasive Ventilation: An Emerging Supportive Technique for the Emergency Department. Annals of Emergency Medicine 32(4):470-9,1998. RT-SER-127 Bipap (Bilevel Positive Airway Pressure) in Clinical Setting. PCG? RT-SER-159 CPAP Therapy for Obstructive Sleep Apnea PCG?
3. Soroksky A. et al A pilot Prospective, Randomized, Placebo-Controlled Trial of Bilevel Positive Airway Pressure in Acute Asthmatic Attack Chest 2003;123;1018-1025.
4. Yosefy C. et al BiPAP Ventilation as Assistance for Patients Presenting with Respiratory Distress in the Department of Emergency Medicine. American Journal of Respiratory Medicine. 2(4):343-7, 2003