|Video annotations Click on a timestamp to navigate through the video.|
00:30CPAP Connection to Oxygen
01:04CPAP Adjustment for Patient Comfort
01:34CPAP Flow Rate Setting
|Equipment and materials|
EMS Jump Bag|
CPAP Equipment Setup
Oxygen tank with regulator
|More video data|
CPAP administration is included in this California-based EMT program for completeness, reflecting its use as evolving standard of care. It is not required for National NREMT registration or skills verification for California Registration.
Continuous positive airway pressure (CPAP) is a non-invasive positive pressure ventilation (NIPPV) that is rapidly becoming the new standard of care. CPAP has been shown to help improve the work of breathing and oxygenation for individuals with obstructed airways/COPD or fluid filled alveoli secondary to infection or cardiovascular failure. CPAP may reduce the likelihood that the patient will need more invasive airway management.
Equipment[edit | edit source]
While equipment varies among manufacturers, CPAP sets designed for field use have a generator powered by an oxygen source that can deliver 50 psi, and are typically attached to the DISS port of a regulator. Some generators have a fixed flow rate, while others can be adjusted. The units typically come in a prepackaged kit which includes:
- Oxygen source/generator, either adjustable or fixed flow
- A face mask with adjustable straps,
- Corrugated tubing to stretch between the tank and the patient
- Bacteria filter
- PEEP valve. Some PEEP valves have integrated input valves for attaching a nebulizer
CPAP treatment can exhaust a small portable oxygen cylinder (D Tank) in under 15 minutes. In order to not interrupt treatment, the EMT should consider either preparing the patient for transport immediately after CPAP treatment has been initiated or bringing additional oxygen cylinders with you when you arrive on scene when dispatch indicates the call involves dyspnea.
Assembly and Application[edit | edit source]
- Start by connecting the corrugated tubing, filter and PEEP valve to the oxygen source/generator according to the manufacturer’s directions and setting the PEEP valve to a low setting.
- Set up an oxygen tank with a regulator containing a DISS port connection, and open the tank valve, pressurizing the regulator. Ensure the regulator valve that is used for supplying low pressure oxygen to patients through nasal cannulas or non rebreather masks is closed.
- Connect the oxygen source/generator to the DISS port of the regulator (taking care to not cross thread). When fully seated into the DISS port, oxygen will start to flow through the generator without needing to turn the dial of the regulator.
- Apply the mask to the patient and secure with the enclosed straps to ensure that there is an airtight seal (similar to a bag-valve mask). For patients experiencing anxiety, have them hold the mask themselves to get used to it before the straps are applied, and encourage them to breathe in through their nose and exhale through their mouth against the pressure.
- Adjust the PEEP valve. Common settings for prehospital CPAP are between 5 to 10 cm water and are typically determined by individual County EMS Protocols.
- For adjustable generators, adjust the FiO2 as needed. The percentage of oxygen delivered (FiO2) usually starts at 30% and can be increased, depending on the needs of the patient.
- Continuously monitor the patient, checking their SpO2 and any changes in work of breathing.
Because the pressure created by CPAP never falls to zero throughout the breathing cycle; the patient will feel "back pressure" during the exhalation phase. This can be uncomfortable, especially for those who have never experienced it before. One way of describing it is that "It will feels like they are sticking their head out of a car window". Many patients with a history of COPD or congestive heart failure have been on CPAP, and while they may be familiar with it, it can still produce considerable anxiety requiring coaching throughout the treatment.
Most prehospital EMS systems incorporate nebulizer medication administration through the CPAP device. Administration of such medications is outside of the scope of practice of EMTs without medical direction. If directed, attach the nebulizer tubing to the oxygen port on the regulator used for supplemental oxygen, and open the regulator to the specified setting for the nebulizer equipment being used. A single regulator can drive both the CPAP and the nebulizer from separate ports. Once applied, the CPAP mask may be removed for a few seconds to administer sublingual nitroglycerin or other oral medications if indicated.
Indications[edit | edit source]
Indications for CPAP in patients over 8 years old in respiratory distress include:
- Chronic obstructive pulmonary disease (COPD) (including emphysema, chronic bronchitis, and asthma),
- Acute bronchitis and pneumonia,
- Toxic inhalation(s) ( i.e. chlorine)
- History of Congestive Heart Failure (CHF) with Pulmonary Edema, rales, and one or more of the following:
- Pedal Edema, Orthopnea, Anxiousness, Diaphoresis, Taking Digoxin or Lasix, Severe or sudden onset of SOB, Rales or coarse wheezes or Hypertension
CPAP may be beneficial in patients who have had significant water inhalation in a near drowning or severe respiratory distress with rales not related to CHF
- Age < 8 years old
- Cardiac arrest, Respiratory arrest, Coma/Unresponsive, or any condition requiring immediate intubation.
- Agonal respiration or an inability to maintain patent airway
- Systolic Blood Pressure <90 mmHg
- Major head trauma especially a head injury with changes in Intra cranial Pressure (ICP) or Facial anomalies or trauma (e.g. burns, fractures)
- Major chest trauma especially a chest injury that could produce a pneumothorax
Use caution in patients with history of:
- Asthma and/or COPD with a recent exacerbation
- Pulmonary Fibrosis
- Decreased LOC
- Claustrophobia, or unable to tolerate mask (after mask 1-2 minutes trial)
CPAP is considered comfort care for patients with do not resuscitate (DNR) status (i.e. advanced disease or terminal illnesses with a filed Physicians Order for Life-Sustaining Treatment (POLST)) and as such should be offered and never withheld based on DNR status.
Mechanism of Action[edit | edit source]
To fully understand indications and contraindications for CPAP, it is important to understand how it is affecting the patient.
In order for the red blood cells to pick up oxygen molecules from each inspiration and for carbon dioxide to be released from the bloodstream during each exhalation, air must be able to reach the thin, elastic walls of the alveoli where gas exchange can occur. Within a properly functioning alveolus is a thin surface layer of liquid called surfactant, which reduces water surface tension within the space and keeps the alveolus open, or allows it to easily re-open. Many pathologies can disturb this balance, causing the alveoli to collapse and gas exchange to be compromised. Using CPAP forces a continuous low level of air pressure through the pulmonary tree which has the following key effects:
- CPAP helps keep the distal alveoli airways open during the inhalation process and prevent them from collapsing during exhalation
- The pressure also keeps smaller airways leading to the distal alveoli from collapsing which avoids having CO2 rich air trapped in the alveoli beyond.
- CPAP can change the pressure across the alveolar wall, which can shift intra-alveolar fluid buildup secondary to congestive heart failure out of the alveoli and back into the vasculature compartment which may also improve tidal volume for the patient.
- The positive pressure may increase the alveolar surface area to improve gas exchange minimizing the retention of CO2
- Avoiding complete alveolar collapse during expiration reduces the forces for overcoming the surface tension on the walls of the alveoli during re-opening which helps to reduce the overall work of breathing.