Introduction to Bubble Continuous Positive Airway Pressure (bCPAP) (Chapter 7/ E7)

See charts for CPAP (TRY algorithm, increasing and weaning)

Learning Objectives

After completion of this chapter the participant should be able to:

Bubble Continuous Positive Airway Pressure (bCPAP)

Definition:

A process of giving continuous flow of air under regulated pressure through the airway.

E7 Bubble CPAP

Clinical Problem

Bubble CPAP (bCPAP) devices provide both positive pressure & increased fractional concentration of oxygen (FiO2) to newborns with respiratory distress.

Bubble CPAP (bCPAP) is particularly useful for premature babies with RDS: respiratory distress syndrome.(1.1)

Very premature babies (<1.5kg and <32 weeks) benefit from early bCPAP. (Alert 1.1) Reference can be made to the TRY algorithm. Depending on your facility and your national policy the lowest weight at which to commence bCPAP may differ. bCPAP should only be used when essential newborn care is in place, the equipment is functioning, oxygen is available, staff are adequately trained in bCPAP, and close monitoring can be assured.

? ALERT 1.1: When do you inititiate bCPAP vs low flow oxygen?

Regarding the initiation of bCPAP versus low flow oxygen on the day of birth, protocol developers should consider the following functions and evidence. bCPAP functions to treat respiratory distress by improving both ventilation (controlled provision of continuous inspiratory pressure) and oxygenation [controlled provision of increased percentage of oxygen - termed the fraction of inspired oxygen (FiO2)]. The positive pressure from bCPAP prevents lung tissue (alveolae) from collapsing on expiration thus improving ventilation, reducing the work of breathing and preventing potentially irreversible lung damage.1 Additionally, bCPAP has been shown to promote production of endogenous surfactant,2 improve apnoea of prematurity3,4 and dramatically decrease progression to mechanical ventilation,5-9 or death, in both high income10,11 and low income 12-15 settings.

Thus, early bCPAP for preterm & small newborns, especially in settings where mechanical ventilation and surfactant are unavailable, is critical to prevent death. At a minimum, evidence points to preferential early initiation of bCPAP, rather than low flow oxygen, in preterm newborns under 1.5kg with any respiratory distress on the day of birth.

Bubble CPAP may also be used to treat neonatal patients with increased work of breathing, designated by nasal flaring, grunting, head nodding, severe recession, RR > 60, or an oxygen requirement of 0.5 to 1 L/min with peripheral blood saturations of < 90%, in premature or term infants. (Alert 1.2)

Increased work of breathing may be caused by:


The TRY algorithm may be used by a nurse or clinician to decide who would benefit from bCPAP and, if necessary, whom to prioritise. The TRY algorithm signs and symptoms on which to act are straight forward and easily carried out. Premature babies benefit most from CPAP and are given priority. Babies with severe asphyxia leading to poor tone will not benefit. If CPAP machines are few in number, it is important to provide CPAP to those who will benefit most. There are always exceptions and in tertiary care units a paediatrician may decide to give CPAP to other infants. Deciding when to start CPAP for a premature baby may differ between national guidelines.

Contraindications to bCPAP include:

Severely asphyxiated babies (with severe hypoxic ischaemic encephalopathy) do not benefit from bCPAP.

? ALERT 1.2 bCPAP & low flow oxygen context
Scale & delivery of neonatal care is critical. However, epidemiological data has shown that rapid scale up of neonatal care without sufficient attention to safety has long term negative consequences for neonatal morbidity16 and is likely a contributor to the epidemic of preventable blindness due to retinopathy of prematurity (ROP) in these settings.17

Supplemental oxygen is life-saving. However, when given in supraoptimal doses, it has also been associated with ROP,18 bronchopulmonary dysplasia,19 periventricular leukomalacia and prolonged ventilation.20 When using any form of oxygen therapy, it is important to closely monitor blood oxygen saturation (SpO2) levels in order to balance risks and benefits of supplemental oxygen. Exact blood oxygen saturation targets for premature newborns remain an area of controversy. However, most authorities agree that SpO 2 between 90-95% is reasonable to minimise complications associated with low and high oxygen levels.21-24

When choosing between low flow oxygen and bCPAP it is important to keep the following physiological considerations in mind. Newborns under 2.5kg receiving low flow oxygen exceeding 0.5 L/min are administered 40-100% effective FiO2,25-28 which may increase morbidity. Delivery of low flow oxygen in preterm newborns under 1.5kg has the added complexity that positive pressure can be delivered even at flows as low as 1-2.5 L/min.29,30 Unfortunately, as discussed above, at these rates of low-flow oxygen, preterm newborns would be exposed to elevated levels of effective FiO 2 which data show are likely to increase their morbidity.

In light of the above evidence and expert opinion, the recommendation was made by our consortium to consider bCPAP in appropriate settings when low flow oxygen greater than 0.5 - 1 L/min is required to maintain saturations >90%. Of note, this recommendation is in line with the WHO recommendation that a standard flow rate for neonates is 0.5 – 1L/min in WHO Oxygen Therapy for Children;31 however, it is unaligned with the suggestion to consider 4L/min of oxygen as the transition threshold from nasal prongs to bCPAP.

bCPAP outside the neonatal period is not addressed by NEST360° materials.

TRY BCPAP ALGORITHM

Zoom in to see details

Assessment

Respiratory distress can cause hypoxia contributing to both morbidity and mortality. Bubble CPAP devices (2.1) use a pump to provide a blend of air and oxygen at a continuous positive pressure. This pressure keeps airway spaces open and increases alveolar recruitment throughout respiration in a spontaneously breathing infant, which improves oxygenation and reduces work of breathing.

Zoom in to see details

Traditional bCPAP devices are made up of the following components:

bCPAP devices range in complexity from vitals measured (e.g., saturations/respiratory rates measured on the device) to outputs (e.g., humidified pressure vs pure pressure). (Alert 2.1)

Pressures used in bCPAP devices range from 5 to 10 cm of water. As bCPAP delivers a blend of air and oxygen, staff should also carefully monitor patients for oxygen saturation using a pulse oximeter. Neonatal patients should reach oxygen saturations of 90 – 95% by 15 minutes after birth. (Alert 2.2)

? ALERT 2.1 Use of humidification in bCPAP

Some bCPAP units use heated and humidified gas in the circuit although the exact benefits of humidification in non-invasive ventilation (i.e., bCPAP) in terms of survival, complications from therapy & morbidity are not well established. For a more thorough review of theoretical risk/benefits of heated humidified oxygen in bCPAP, see Appendix 1.

Potential benefits of heating and humidification could include:

  • Increased comfort and adherence.
  • Decreased upper airway mucosal injury.
  • Decreased convective heat losses which may lead to hypothermia & challenging weight gain in infants.
  • Decreased lung inflammation from mucus plugs which has unknown impact on morbidity & mortality of very low birth weight infants.
Potential drawbacks to heated humidification include:
  • Hospital-acquired infection, especially in settings where clean water may not be readily available and humidifiers, which are typically meant for one-time use, are being cleaned and re-used between patients.32
  • High financial cost of adding heated humidified gas.33
  • High human resource cost in terms of repair and preparation of non-invasive ventilation units which may limit not only their use, but availability of this life saving technology within our setting.33

In summary, based mostly on expert opinion, it is likely that heated and humidified air is most important for the smallest newborns <1 -1.25kg although this has never been explicitly studied. There is evidence from Malawi that unheated un-humidified bCPAP can be used successfully to decrease mortality of infants without excessive reports of upper airway complications, but physiological implications in terms of morbidity and mortality (hypothermia & weight gain) were not explicitly studied. Of note, survival of infants >1.5kg on un-heated un-humidified air bCPAP in this study12 were similar to survival of infants >1.5kg in Rwanda on heated and humidified bCPAP.34

At this time, based on expert opinion and available literature, it does not appear that the benefits of humidification outweigh the potential risks/drawbacks for infants >1kg. Further study of the degree of humidity provided by compressed air in various settings as well as implications of humidification in low resource settings on iatrogenic infections, morbidity, and mortality of neonates is needed.

? ALERT 2.2: SpO2 & Safe Oxygen Delivery
When making this recommendation the following resources were considered:
  1. According to the Textbook of Neonatal Resuscitation (NRP), 7th Ed., “After birth, the oxygen saturation gradually increases above 90%. However, even healthy term newborns may take 10 minutes or longer to reach this saturation” (p.77).35
  2. Target peripheral oxygen concentrations (SpO2) for newborns vary depending on age and clinical condition. However, most authorities agree that saturations between 90-95% minimises the complications associated with both low and high oxygen levels including death, neurodevelopmental impairment and Retinopathy of Prematurity.21-24

Management

Management of bCPAP covers how to use the bCPAP device including set up for a patient, patient preparation & commencement, care whilst on the device & removal of the patient from the device.

SETTING UP FOR A PATIENT

  1. Collect: (3.1)




PREPARING A PATIENT

  1. Place patient on oxygen and keep the baby warm whilst preparing for bCPAP.
  2. Always explain the purpose, risks, and benefits of a procedure to guardians BEFORE performing the procedure.
  3. Follow handwashing protocol.
  4. Collect:
  5. If a hat is not available, make a hat from a length of stockinette. (3.11)
  6. Wash hands and put on gloves. Using suctioning guidelines, suction the patient’s nose and mouth using the suction catheter if clinically indicated. (3.12)


  7. Insert an OGT: (Alert 3.1)

    1. Place the patient’s head in a neutral position, measure from the middle of the mouth to the ear and then to halfway between the xiphisternum and umbilicus. Mark this distance with a small amount of tape.
    2. Gently insert the OGT in the mouth to this length.
    3. Tape the OGT to the chin to keep in place. Use appropriate tape for delicate newborn skin.
    4. Check placement of the OGT.36
    5. Select bCPAP prong size from 000 to 5 based on nostril size. bCPAP prongs should completely fill the patient’s nostrils. If prongs do not fill the nostril completely, the pressure delivered to the patient will be decreased. If nostrils turn a white colour the prongs are too tight and should be exchanged for the next size down.

STARTING A PATIENT

  1. Collect: (3.13)
  2. Turn on the bCPAP device and connect oxygen source. Place hat on patient.
  3. Determine initial settings for the patient. Most patients will start with a pressure level of 6 cm water, total flow of 6 L/min and oxygen concentration (FiO2) of 50%. Determine oxygen flow using FiO2 and total flow as shown on the oxygen blending table printed on top of device. (3.14)
  4. Set total flow. Set oxygen flow on both oxygen source and bCPAP oxygen flowmeter.
  5. Connect correctly sized bCPAP prongs to the inspiratory and expiratory tubing. Retest the bubbling by pinching the bCPAP prongs shut.
  6. If the water within the pressure regulating bottle bubbles:
  7. Secure inspiratory and expiratory tubing to the patient using hat clips. (3.16) If hat clips are unavailable, secure using rubber bands & safety pins:


  8. Check that the water within the pressure regulating bottle bubbles. If it does not bubble, check that the prongs completely fill the patient’s nostrils. If they do not, replace with appropriately sized prongs.
  9. Monitor the patient 15 minutes after initiating bCPAP treatment and then 4 hourly for:
  10. Act in accordance to clinical findings.

CARING FOR A PATIENT

Monitoring the patient should be completed 4 hourly, but may be required more frequently depending on clinical condition. Monitoring should include:

At every monitoring point:

  1. Provide a drop of saline to each nostril. (3.18)
  2. Check prongs, tubing & hat:
  3. Prongs should not be against nasal septum and check for skin compromise
  4. Check water level: if water level is below decided treatment level, add water into bottle cap hole using a syringe or OG tube. (3.19) Water should be changed daily.

Prior to increasing bCPAP always ensure the bCPAP device is functioning well and all parts are in place. One mnemonic to help with this is DOPE:

Increases in treatment are made in accordance to the Increasing bCPAP Treatment algorithm.

INCREASING BCPAP

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REMOVING A PATIENT

Refer to the following Weaning a Patient from bCPAP Treatment flow chart:

Zoom in for details.

Infection Prevention

Infection prevention, especially when using humidification or re-processing respiratory circuits intended for single use, is CRITICAL to preventing equipment related infections in newborns. If devices and equipment are not disinfected or re-processed promptly or adequately between patients, they may pose a significant infection risk.

GENERAL INFECTION PREVENTION

  1. Clean hands with soap and water or 70% alcohol before and after placing a patient on bCPAP or handling any tubing that will be used on a patient.
  2. Ensure that all patient-related tubing (including prongs, inspiratory, and expiratory tubing) is new or has been cleaned thoroughly and dried as per reuse guidelines. (Alert 4.1) Any patient-related tubing must be cleaned before it is used to place another patient on bCPAP. Nasal prongs are especially difficult to clean thoroughly. Tubing should be hung to dry after disinfection and should not touch the floor or other unsanitary surfaces whilst drying. Any item falling on the floor is contaminated and must be cleaned thoroughly again.
  3. All patient-related consumables should be stored in a clean, dry location. Tubing should be stored in loose rolls, preventing sharp bends or kinks which will decrease the lifetime of the tubing.
? ALERT 4.1: Re-processing single-use devices
Respiratory circuits and humidifiers associated with bCPAP are generally intended as single use devices. However, in areas with limited resources or challenging supply chains this equipment is often re-used. When reprocessing single use devices it is extremely important that the process is not delayed following completion of use. There should be a detailed standard of practice as well as oversight processes for ensuring timely and high-quality re-processing. If equipment is not re-processed promptly or adequately between patients it poses a significant infection risk. Please refer to the Reference Manual for Health Care Facilities with Limited Resources Infection Prevention and Control Module 637 for more detailed guidance on the re-processing of single use devices.

DISINFECTION AFTER USE

  1. Turn off bCPAP and dispose of water within pressure regulating water bottle.
  2. Dispose of hat and follow protocols for cleaning tubing if reusing prongs, inspiratory and expiratory tubing. If patient consumables are not cleaned thoroughly before using, infection can be transmitted. Care should be taken particularly for consumables that are marked as single-use but are practically reused.
  3. Clean the outside of the bCPAP device using a swab soaked in alcohol or diluted chlorine. Total and oxygen flowmeter regulator controls should be disinfected after each use using a cotton swab or gauze soaked in 70% alcohol.

Complications

Introduction of equipment in newborn care units poses clinical and device complications for patients. Awareness of potential complications is critical to maximise patient safety.

CLINICAL COMPLICATIONS

DEVICE COMPLICATIONS

Care & Maintenance

Users are responsible for basic first-line care and maintenance to ensure equipment lasts to their potential lifetime.

POWER SOURCE

Mains power.

WARD LOCATION

The bubble CPAP device should be secured in an easily accessible and visible location near an oxygen source where nursing staff can regulate flows and manage patients easily, but where it is not at risk of falling. All consumables required to place a patient on bCPAP should be near the device and readily available to start treatment. bCPAP devices vibrate during use; ensure that the vibration is not causing excess sound (e.g., if placed on a table with metal instruments that will vibrate with the bCPAP device).

USER PREVENTIVE MAINTENANCE

Minimal preventive maintenance is required for bCPAP devices. The bCPAP device should be turned on weekly to a total flow of 10 L/min and allowed to run while connected to an oxygen source at 2 L/min for at least 15 minutes. This is important to ensure device functioning and minimise infection risk within internal respiratory circuits.

Troubleshooting & Repair

Although users are not responsible for repairing their devices, there are steps that may be taken to troubleshoot first-line errors that may occur before contacting maintenance or engineering support.

1 The device does not turn on
  • Check that the power cable is securely attached (7.1) and connected to the socket.
  • Check that the power at the socket is turned on.
  • If the machine still does not turn on, contact your maintenance team.

2 If the silver balls in the oxygen or total flowmeters are not going up
  • Tap the front of the flowmeter firmly with your knuckle or the handle of a screwdriver (or similar).
  • If the flowmeter silver balls still do not go up, contact your maintenance department to request cleaning of the flowmeter and to check that all internal tubing is still connected.

3 If the total flowmeter does not go up to 10L/min
  • Contact your maintenance department to request an internal filter change.

4 If the water in the bottle is not bubbling
  • Check that the bCPAP prongs fully fill the nostrils and that the patient’s mouth is not open. If the prongs do not fully fill the nostrils, replace the prongs with a larger size.
  • If the prongs are well-fitted, remove from the patient’s nose and occlude the prongs with your finger. If the water is still not bubbling check the seal at the patient port. If the seal is deteriorating or cracked (7.2), contact your maintenance department to replace or troubleshoot further.

Appendix 1

Heated & Humidified Air in Non-Invasive Ventilation

When breathing, air is physiologically heated and humidified as it passes through our upper airways into the lungs. Artificial heating and humidification are essential in invasive ventilation (i.e., when using ventilators) which bypasses the upper airways. However, the risks and benefits of heating and humidifying air supplied through non-invasive ventilator techniques such as Highflow Nasal Cannula (HFNC) and bCPAP are not well established and currently there is not consensus about whether or not it is a necessary element of all non-invasive ventilation systems.38,39

Benefits of heated and humidified gas in non-invasive ventilation may include increased adherence and comfort.38 In neonates specifically, there is a physiological argument that removal of heated and humidified gas may lead to increased convective heat losses and therefore increased metabolic demand as well as increased insensible fluid losses. One needs to consider if these effects may or may not have significant effects on the infant’s ability to maintain their temperature and grow adequately during the first weeks of life impacting mortality. In the long term, the effect of removing humidification on morbidity of infants (specifically in terms of development of bronchopulmonary dysplasia) is also unknown.40 Lastly, heated humidified bCPAP may lead to lower incidence of mucosal injury which, in one study, was linked to increased rates of sepsis in extremely low birthweight infants41; however, early data from Malawi demonstrated few mucosal injuries when using un-heated un-humidified bCPAP.12

Risks of humidification include a theoretical risk of infection especially in settings where clean water may not be readily available and humidifiers, which are typically meant for one time use, are being cleaned and re-used between patients.32 In addition, humidification incurs a high financial cost as well as human resource costs in terms of repair and preparation of non-invasive ventilation units which may limit not only their use, but availability of this life saving technology within low resource settings.33

There is reason to believe that when supplying ambient air through the upper airway there is in fact, no need for heated humidification. 33 This may be doubly true in low resource bCPAP units such as the Pumani which, rather than using compressed air sources (i.e., cylinders) are in fact driving flow through the circuit using compressed ambient air.42 It is worth noting that although some lower cost bCPAP models do offer passive humidification, expert opinion and experience suggests that perhaps the level of humidification achieved via this method is not significant (data unpublished). Of note, although the studies differ significantly, reported survival rates for infants >1.5kg in Rwanda on a heated and humidified bCPAP circuit34 were similar to those reported in Malawi on an un-heated, un-humidified circuit.12

In conclusion, despite recent WHO recommendations that bCPAP units should contain humidification.31 In light of primary data which shows (1) the unknown necessity, (2) the risks and benefits of heated and humidified gas in non-invasive ventilation, and (3) the life-saving implications bCPAP has for neonates, our consortium maintains there is a lack of evidence to resolve the question of humidification at this time. Further study of the degree of humidity provided by compressed air in various settings as well as implications of humidification in low resource settings on iatrogenic infections, morbidity and mortality of neonates is needed. It is important that when considering implementation of bCPAP, one considers not only physiological implications of this feature in the bCPAP units, but also how this feature impacts supply chain, human resource costs, financial costs, training, infection control, maintenance, and availability of units in country.

References


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