C P A P
Continuous Positive Airway Pressure
Mesfin Woldesenbet, M.D.
Neonatal-Perinatal medicine
Pediatrix Medical Group
August 2011
Abbreviations
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•
•
•
•
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FRC: Functional Residual Capacity
RDS: Respiratory Distress Syndrome
HMD: Hyaline Membrane Disease
TTN: Transient Tachypnea of the Newborn
PEEP: Positive End-Expiratory Pressure
CPAP: Continuous Positive Airway Pressure
Historical Perspectives
• Early 1950’s- Iron lungs used in polio
epidemic were the first successful
negative pressure ventilators.
• Late 1950’s- Volume-controlled, positive
pressure ventilators were designed
• 1959 the first of such ventilators were
used on newborns
Historical Perspectives – cont.
•
Early 1960’s - assisted ventilation for hyaline
membrane disease became more common,
but was used only with strict criteria
*pH less than 7.0
*PO2 < 30-40 mmHg in 100% oxygen
*Paco2 greater than 80 mmHg
These were very sick newborns
Historical Perspectives - cont
• In 1971 CPAP using an endotracheal tube
was a breakthrough in the treatment of
newborn RDS which demonstrated
dramatic improvement of oxygenation.
Historical Perspectives –cont.
• In 1973 CPAP using nasal catheters
positioned in the midnares was used on
infants weighing >1500gms who had RDS
requiring >60% oxygen to maintain a PaO2
of 50-60 mmHg.
• These early interventions increased
survival of preterm infants.
CPAP today
• It is Continuous Positive Airway Pressure
applied to the airways of a spontaneously
breathing patient throughout the
respiratory cycle. It is accomplished by
nasal prongs that provide heated and
humidified oxygen mixtures continuous or
variable flow from a circuit connected to a
ventilator set in CPAP mode or a bottle
filled with liquid (Bubble CPAP).
PEEP/CPAP
• LaPlace’s law: It is difficult to blow up a small balloon the
first time because it takes more applied pressure to start
the stretching process necessary for inflation.
• The difficulty of inspiration during the baby’s first breath
is great because all the balloons (i.e. alveoli) must be
inflated from a collapsed state
• Premature infant’s alveoli are even more difficult to
inflate because of the lack of surfactant, which coats the
alveoli and reduce surface tension.
• The oxygen exchange from air to blood is proportional to
the surface area of the exchange membrane (alveoli).
Law of LaPlace : P = 2T/r
P : pressure
Larger alveolus
r=2
T=3
P = (2 x 3) / 2
P=3
T : surface tension
r : radius
CPAP
Smaller alveolus
r=1
T=3
P = (2 x 3) / 1
P=6
Benefits of PEEP/CPAP
• PEEP keeps the alveoli open at the end of
expiration so that they do not stick together and
are easier to re-inflate.
• This results in increased surface area in the
alveoli for better oxygen exchange from the air
to blood.
• Controlled PEEP has been shown to improve
oxygenation when used for babies who need
more than normal resuscitation at birth but are
breathing spontaneously.
Desired Outcomes for all methods
of Ventilatory Support
• Reduction in the work of breathing as indicated
by a decrease in respiratory rate by 30-40%.
• Reduction in the severity of retractions, grunting
and nasal flaring.
• Improved lung volumes and appearance of lung
on X-RAY
• Improved patient comfort (assessed)
• Reduction in apnea, bradycardia and cyanosis
Effects of CPAP
1. Increases transpulmonary pressure and functional
residual capacity (FRC)
2. Prevents alveolar collapse, decreases
intrapulmonary shunt and improves lung
compliance
3. Conserves surfactant
4. Prevents pharyngeal wall collapse
5. Stabilizes the chest wall
6. Increases airway diameter and splints the airways
7. Splints the diaphragm
8. Stimulates lung growth
Indication of CPAP
1. Diseases with low FRC, e.g. RDS, TTN,
PDA, pulmonary edema, etc.
2. Apnea and bradycardia of prematurity
3. Meconium aspiration syndrome (MAS)
4. Airway closure disease, e.g. BPD
5. Tracheomalacia
6. Partial paralysis of diaphragm
7. Respiratory support after extubation
Meconium Aspiration Syndrome
(MAS)
Inspiration
Expiration
Meconium Aspiration Syndrome
(MAS)
With CPAP
No CPAP
CPAP Devices
• Head hood
• Face shield
• Face mask
• Nasal mask
• Nasal prongs – Hudson, INCA, Draeger,
Fisher&Pakel, SiPAP, Arabella, NeoPAP
• Nasal cannula – Vapotherm
• Nasal pharyngeal tube
• Endotracheal tube
Nasal CPAP
Set up ( 1 )
1. Oxygen blender
2. Flowmeter(5-10 LPM)
3. Heated humidifier
4. Thermometer
5. Inspiratory tubing
6. Nasal cannulae
7. Velcro
Nasal CPAP
Set up ( 2 )
8. Manometer (optional)
9. Expiratory tubing
10. A bottle containing a
solution of 0.25%
acetic acid filled up to
a depth of 7 cm.
Distal tubing
immersed to a depth
of 5 cm to create +5
cmH2O
Nasal CPAP
Application (1)
1. Position the baby in
supine position with
the head elevated
about 30 degrees
2. Place a small roll
under the baby’s neck
3. Put a pre-made hat
or stockinet on the
baby’s head to hold
the CPAP tubings
Nasal CPAP
Application (2)
4. Choose FiO2 to
keep PaO2 at 50’s
or
O2 saturation at
85% – 95%
Nasal CPAP
Application (3)
5. Adjust a flow rate 510 Lpm to:
a) provide adequate
flow to prevent
rebreathings CO2
b) compensate leakage
from tubing
connectors and
around CPAP prongs
c) generate desired
CPAP pressure
(usually 5 cmH2O)
Nasal CPAP
Application (4)
6. Keep inspired gas
temperature at 3640O C (0 ~ –3)
Nasal CPAP
Application (5)
7. Insert the lightweight
corrugated tubing
(preferrably with
heating wire inside) in
a bottle of 0.25%
acetic acid solution or
sterile water filled up
to a height of 7 cm.
The tube is immersed
to a depth of 5 cm to
create 5 cmH2O
CPAP as long as air
bubbling out of
solution
Nasal CPAP
Application (6)
8. Choose the
proper size of
nasal Cannulae
CPAP Cannulae
Size
B.W.
0
1
2
3
4
5
< 700g
~1000g
~ 2000g
~ 3000g
~ 4000g
infant
Nasal CPAP
Application (7)
9. Lubricate the
nasal CPAP
prongs with sterile
water or saline.
Place the prongs
curved side down
and direct into
nasal cavities
Nasal CPAP
Application (8)
10. Secure
tubings on both
sides of the hat
with either
safety pins and
rubber band
or velcro
Nasal CPAP
Maintenance (1)
1. Observe baby’s vital signs, oxygenation and
activity
2. Systematically check CPAP systems, inspired
gas temperature, air bubbling out of acetic acid
solution. Empty condensed water in the circuit
3. Check CPAP prongs position and keep CPAP
cannulae off the septum at all times. A snug
cap is used to securely hold the tubings in place
and using self-adhesive Velcro to keep
cannulae away from the septum if necessary
Nasal CPAP
Maintenance (2)
4. Suction nasal cavities, mouth, pharynx
and stomach q4h and prn
5. Change the baby’s position
6. Change CPAP circuit once a week
Nasal CPAP
Weaning
• CPAP is kept at 5 - 7 cmH2O
• FiO2 is adjusted to keep PaO2 in
50’s, or oxygen saturation around
85%-95%
Nasal CPAP
Discontinued
• No tachypnea or retraction
• No apnea and bradycardia
• FiO2 is usually room air
Nasal CPAP
Complications
• Nasal obstruction from secretions or
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•
•
•
improper application of nasal prongs
Gastric distention from swallowing air
Nasal septum erosion or necrosis
Fluctuating FiO2
Air leak: <5%, usually occurs during acute
phase
Success with Early NCPAP and
Incidence of BPD
Percent use of ENCPAP
33%
Incidence of BPD
6%
Aly, H. et al. Pediatrics 115:1660-5, 2005.
References
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