Continuous Positive Airway Pressure

1. JOURNAL
CLUB
BY: Dr.Sajid Noor
F.C.P.S Trainee

2. Continuous Positive Airway Pressure: The
Light that Really does Keep Monster from
Baby Away
Ravi Ambey, Priya Gogia
Department of Pediatrics, Madhya Pradesh,
India
International Journal of Pediatrics Research
and Practice (Published: 10-07-2015 )
Review Article

3. INTRODUCTION
CPAP is a continuously applied
distending pressure (CDP) used for
maintenance of an increased
transpulmonary pressure during
expiratory phase of respiration, in a
spontaneously breathing patient.

4. Cont…
It prevents the alveolar collapse with marginal
stability.
Better recruitment of alveoli thus increases the
functional capacity of lungs .
It result in less ventilator induced lung injury than
mechanical ventilation, hence reduce incidence of
chronic lung disease
It is a simple, low- cost and effective method of
ventilating a sick new born in resource restricted
countries.

5. HISTORY
Harrison 1968: described grunting in neonates
as naturally producing end expiratory
pressure
Gregory et al, 1971: introduced the clinical use
of CPAP in neonates.(via endotrachial tube or
a head box)
Later Kattwinkel reported successful use of
nasal prongs in neonates with RDS.

6. OUTCOME
Following the introduction of CPAP. The
mortality of RDS decreased from 55-35% to
20-15%
It has been documented that atelecto-trauma,
bio-trauma and volu-trauma is less with
CPAP
An improvement which is comparable with
the effect obtained by the introduction of
surfactant 20 years later.

7. DISCUSSION

8. PRINCIPLE
The exact mechanism is still
unclear.
Grunting in a baby with respiratory
distress is an attempt to generate
pressure against closed glottis that
keeps the airway open during
expiration. CPAP works on the same
principle.

9. In a baby with hyaline membrane disease, forced residual
capacity (functional residual capacity [FRC] - the volume
of air that is remaining in lungs after tidal volume) is
reduced below closing volume (volume below which the
terminal bronchioles get closed).
CPAP generates continuous pressure throughout the
respiratory cycle to a point that FRC reaches above the
closing volume, and terminal bronchioles remain patent
throughout the respiratory cycle.

10. PHYSIOLOGY OF CPAP
Increases FRC
Decreases V/Q mismatch
Splints upper airway - airway resistance
Increase tidal volume
Decrease work of breathing
Conserves surfactant
Increase lung compliance

11. DISADVANTAGES OF
CONVENTIONAL VENTILATION
High pressure- Barotrauma
Tidal volumes- Volutrauma
Atelectotrauma
Inflammation & infection- Biotrauma
CV ruptures the interalveolar septa thus
decrease the surface area of gas exchange
despite increasing lung volume.

12. According to Laplace law…
The pressure
generated depends
on surface tension,
and inversely to the
radius of the
substance.

13. Larger alveolus
r = 1.5
T = 3
P = (2 x 3) / 1.5
P = 4
Smaller alveolus
r = 1
T = 3
P = (2 x 3) / 1
P = 6
CPAP
Law of Laplace : P = 2T/r
P : pressure T : surface tension r : radius

14. How CPAP Works…
In RDS, the lack of the surfactant allows the water
molecules (lung fluid) to coalesce and reducing the
radius of the alveoli.
Thereby, more pressure is required to open the
collapsed alveoli.
CPAP splints open the upper airway thus reduces
the airway resistance and keeping the airway
open by negotiating the surface tension.

15. How does CPAP works

16. Cont..
CPAP by generating the pressure also
stimulates the “Hering–Bruer’s” reflex.
It states that stretching of pleura
during the end of expiration stimulates
the respiratory center (in the brain
stem). By this the next cycle of
respiration is initiated.

17. Stretches lung
pleura and upper
airway
CPAP MAGIC
Prevents collapse of
alveoli with
marginal stability
Stabilizes the
chest wall
Splints open
upper airway
Improves pH
Reduces airway
resistance
Recruitment of
alveoli
PaO2
PaCO2
Improves V/Q mismatch and
reduces intrapulmonary shunt
Increased alveolar surface
area for gas exchange
Maintains lung at
FRC
Reduces work of
breathing
Reduces mixed and central
apnea
Reduces
obstructive apnea
Stimulates stretch
receptors

18. Indications of CPAP in
Neonates
 Hyaline membrane disease
 Apnea of prematurity
 Post-extubation in preterm VLBW
 Transient tachypnea of newborn
 Meconium aspiration syndrome
 Pneumonia
 Pulmonary edema/pulmonary hemorrhage
 Laryngomalacia/tracheomalacia/bronchomalacia.

19. Contraindications of CPAP in
Neonates
 Patients with poor respiratory efforts
 Trachea-esophageal fistula
 Congenital diaphragmatic hernia
 Nasal obstructions - choanal atresia, cleft palate
 When PaCO2>60 mmHg, Ph<7.2
 Babies with cyanotic heart diseases
 Relatively the patients with the central cause of
respiratory distress like sepsis, birth asphyxia,
intracranial hemorrhages.

20. BASIC ESSENTIALS IN
CPAP
Every basic CPAP machine requires the following:
1
2
Gas
source
Pressure
generator
Continuous supply of warm
humidified and blended mixture of
air and oxygen
Continuous positive pressure
generation. The pressure
generators are either continuous
type (conventional stand - alone
CPAP, bubble CPAP) or variable
flow type (infant flow meter)

21. 3
Patients
interface
and circuit
Connect the CPAP circuit to infant’s
airway. The various types of
interfaces are
1.Nasal prongs (single/binasal)
2. Nasopharyngeal prongs
3. Nasal cannula
4. Nasal masks

22. HOW THE INDIGENOUS CPAP
(BUBBLE CPAP) WAS MADE?
Bubble CPAP is a continuous flow type of CPAP
pressure generator where the pressure is generated by
immersing the variable length of expiratory limb in
the water chamber.
Bubble CPAP having its origin in 1960’s but its use
never gained much popularity in developing
countries because of cost and maintenance.
The market cost of Indian bubble CPAP is between
50,000 and 80,000 rupees. In resource limited
settings, every tertiary center cannot access to this
life-saving machine.

23. Figure 1: Indigenous continuous positive airway pressure
circuit (self- drawn diagram)

24. ESSENTIALS OF CPAP
Before the initiation, the head end is
elevated 30° via shoulder roll.
1. The flow of gases is adjusted
according to clinical condition
of the patient from 0 to 10
liters/min (usually kept
between 5 and 8 cm L/min).

25. 2..There are two limbs in the circuit
A. The inspiratory
limb is the connection
between flow meter and
patient.
It allows the compress
blended air-oxygen to pass
through humidefier and
humidifies gases at 35-37°C
B. The expiratory limb
starts from the humidifier.
There is bifurcation of the
limb at this point. Through
corrugated tubing one end
attached to patients interface
via nasal prongs and other end
to intercostal chest drainage
bag through ICTD tube. This
tube is immersed in water up
to required depth.

26. Cont..
3. Set the desired flow and pressure.
4. At the patients interface binasal prongs are
attached, which are supported with the
head cap. It prevents the nasal injury due
to the hanging pressure of prongs.

27. 5.The vitals were monitored and the pulse
oximeter was attached.
6. An orogastric tube was inserted to
decompress the stomach or can allow
feeding of newborn on CPAP.
7. Nasal suction was regularly done, and both
nostrils were moistened with normal saline
at regular intervals.

28. 8.Look for bubbling in the water chamber. If no
bubbling occurs any leak in the circuit has to
be looked for. If no leak found then the flow
is increased with 1 liter/mint.

30. THE FAILURE OF CPAP
when with the pressure of 8cm H2O, and the
flow of oxygen is 70%.
The PH of baby is below 7.2.
It is the time when mechanical ventilation
is to be considered

31. CPAP failure was defined as….
SpO2 <88% on FiO2 >60% for >30 minutes
(with requirement of CPAP>8cms of H2O)
Blood gases
showing
PH <7.20
PCO2 ≥ 65 mmHg
PO2 <50 mm Hg
on FiO >60%
Pathologic
apnea
Increasing
Retractions
Ref: Indian Journal of Neonatal Medicine and Research. 2015 April

32. MONITORING DURING THE
PROCEDURE
Vitals - temperature, heart rate, capillary refill
time,pulse oximetry (89-94%), blood glucose.
Respiratory distress score - Silverman for
preterm or Downe’s score for term
Monitor blood pressure, urine output, and
abdominal girth.
Arterial blood gas analysis
Look for nasal trauma, moniter the dryness of
nose.

33. Score: > 4 = Clinical respiratory distress; monitor arterial blood gases > 8 =
Impending respiratory failures

34. A score greater than 7 indicates that the baby is in respiratory failure.

35. Cont..
Patient has to repositioned every 3 hr
with neck slightly extended to
maintain airway
Humidification of the gases should be
checked regularly.
The circuit has to be regularly checked
for leakage

36. Cont..
The tubings must be regularly cleaned and
checked for blockage.
There is no need of daily regular chest X-ray
in monitoring of lung signs
Maintain hydration of the baby
Keep the resuscitation equipment cot side all
the times.
Neurological assessment.

37. WEANING OFF FROM CPAP
After proper monitoring when there are
no signs of respiratory distress
(resolution of grunting, nasal flaring, and
chest retractions) and arterial blood gas
analysis is within normal limits.
FiO2 is gradually decreased in steps of
5% and pressure decreased by 1 cm H2O.
Make sure the baby breathes with less
effort.

38. COMPLICATIONS OF CPAP
Air leaks (pneumothorax)
Agitation
CPAP belly syndrome
Nasal trauma
Hypotension
Increased pulmonary vascular resistance
Chronic lung disease.

39. CPAP BELLY
Abdominal distension
can occur in babies on
CPAP.It is compounded
by presence of
immature gut in
preterms and some
decrease in blood flow
to the gut. All these
together lead to what is
called as ‘CPAP belly
syndrome’

40. RESULTS
Study was conducted on 70 newborns ,32weeks.
Majority of the cases received bubble CPAP.
The incidence of CPAP failure was 30%.
The proportion of neonates who required surfactant was
18.6%.
Who developed ROP was 37.1%
who met with mortality was 7.1%
Nasal Trauma, Hypotension, Intra Ventricular Hemorrhage
and CPAP belly were the most common complications,
occurring in 80%
No case of pulmonary hemorrhage was reported.
Ref: Indian Journal of Neonatal Medicine and Research. 2015 April

41. CONCLUSION
CPAP is now-a-days considered as a first line
therapy for management of RDS in preterm
infants.
Currently, the use of CPAP is increasing due to the
advantage of being less expensive, less damaging and
having reduced incidence of the chronic lung disease
and broncho-pulmonary dysplasia over the use of
invasive mechanical ventilation.
It is an extension of ventilatory support rather
than replacement of mechanical ventilation.

42. THANKS