3. CPAP
l the application of positive
airway pressure
throughout the respiratory
cycle during spontaneous
respiration
l history
l Harrison 1968: described
grunting in neonates as
naturally producing end-
end-
expiratory pressure
l Gregory et al, 1971:
introduced the clinical use
of distending pressure in
neonates
4. Physiologic effects of CPAP
l pulmonary mechanics
l cardiovascular stability
l pulmonary vascular resistance
5. Pulmonary effects
l decrease respiratory rate, tidal volume
and minute volume
l regularization of respiration
l increase FRC and thoracic gas volume
l decrease lung compliance and
dynamic compliance
l decrease total airway resistance
l protective effect on surfactant
6. Effect of CPAP on FRC in the infants with RDS
20
15
10
FRC (ml/kg)
Control
5
+4 torr
0
2 3 4
Age (days)
7. Effect of different CPAP levels on PaO2
300
200
Pa o(torr)
2
100
0
4 8 12 16 20
CPAP (torr)
8. Cardiovascular effects
l compromise venous return results in diminished cardiac
output
l depend on lung compliance
l sign and symptom: tachycardia, metabolic acidosis,
hypotension, decreased dynamic compliance, carbon dioxide
retention
l decrease peripheral and regional blood flow
l decrease oxygen available to tissue
l increase extra-pulmonary shunting secondary to an
increase in pulmonary vascular resistance
9.
10. Effects of CPAP
l Renal function
l decrease renal blood flow
l decrease urine output and urinary sodium excretion
l increase antidiuretic hormone and aldosterone
l Gastrointestinal function
l decrease gastrointestinal blood flow
l abdominal distention (CPAP belly syndrome)
l Intracranial pressure (head box CPAP)
l increase intracranial pressure
l intracranial bleeding
11. Pressure volume curve
is divided into 3 regions
l region A: low lung Turbulent
High-Velocity
Laminar
Low-Velocity
Flow Region Flow Region
volume, low compliance
and high resistance. The .08 10,000
Airway Cross-Section in cm2
Normal
Resistance (cm H2O/L(ml) s)
P/V slope is low Newborn
1000
Volume per
.06
Lung
l region B: optimal lung .04 100
volume and increases .02 10
HMD Lung
lung compliance 2
l region C: high lung 0 5 10 15 20
volume, low lung Airway Generation2O)
Pressure (cmH
compliance
Pressure- volume curve
13. Clinical applications of CDP or CPAP
l respiratory distress syndrome
l meconium aspiration syndrome
l apnea of prematurity
l postoperative thoracotomy
l patent ductus arteriosus
l postoperative celosomia
l weaning patients from primary lung disease
l differentiation of primary lung disease from primary
cardiac disease
l as adjunct to intermittent positive ventilation
l sleep apnea
l bronchomalacia
14. Clinical applications of CPAP
Low (2-3 cm H2O)
Use Side effects
l maintenance of lung volume in l may be too low to maintain
VLBW infants adequate lung volume or
l during weaning adequate oxygenation
l during hyperventilation in
PPHN
Medium (4-7 cm H2O)
Use Side effects
l increasing lung volume in If lungs have normal compliance
surfactant deficiency l over distention
l stabilizing areas of atelectasis l impede venous return
l stabilizing obstructed airway l air leak
15. High (8-10 cm H2O)
Use Side effects
l preventing alveolar collapse l air leak
with poor CL and poor lung l decreased CL if over distended
volume l may impede venous return
l improving distribution of
l may increase PVR
ventilation
l CO2 retention
Ultrahigh (11-15 cm H2O)
Use Side effects
l tracheal or bronchial collapse l air leak
l markedly decreased CL or l decreased CL if over distended
severe obstruction l may impede venous return
l preventing white-out or re- l may increase PVR
establishing lung volume during l CO2 retention
ECHO
17. Optimal CPAP level
Disease Physiology Optimal CPAP level
Acute RDS l significant A-a gradient l PaO2
l rapid change compliance l oxygen consumption
l oxygen delivery
Small premature l small A-a gradient l lung compliance
infant weaning off l weak respiratory muscles
CPAP l increased chest wall
compliance
BPD on 60% l decreased compliance l pulmonary mechanics:
oxygen l increased resistance resistance, compliance
4-day-old RDS l congestive heart failure l balance between
and PDA and pulmonary edema cardiac output and
pulmonary blood flow
18. Clinical use of CPAP
l clinical indications l follow up and
l sign of atelectasis on weaning
chest film l follow-up PaO2 within
l chest wall retraction 15-20 min.
l require FiO2>0.5 l weaning
l display rapidly l after oxygenation
progressive lung disease was improved
l initial pressure setting l extubation from
l nasal or nasopharyngeal: CPAP 3-4 cm H2O
6 cm H2O
l endotracheal: 4 cm H2O
19. Nursing care of CPAP
l method l nursing care
l nasal l continuous care (oxygen,
l nasopharyngeal pressure)
l endotracheal tube l care of airway
l face mask l prevent obstruction
l components l prevent irritation of
l oxygen nares
l temperature and l skin care
humidity l abdominal distention
l pressure l NPO
20. Indication of CPAP
Atelectatic disorders
l PaO2 below 50-60 mm Hg in FiO2>0.6
l recurrent apnea
Initial setup
l CPAP 6 cm H2O
l increase 2-cm. increments q 15 min. to a max.
of 10 cm H2O or 12 cm H2O
l increase FiO2 0.05-0.10 if PaO2<50 mm H2O
21. Respiratory distress syndrome
l improve survival rate,
especially larger infants
l modify course of the disease
l lower max.FiO2 required,
reduce total amount of time
under O2 and the need for
mechanical ventilation
22. Early CPAP in RDS
l was proved to be more beneficial in the
atelectatic disease
l lower peak pressure required in infants treated
with CPAP
l enhance surfactant conservation
l reduce the need for IMV by 20%, except infants
with birth weight <1500 g.
l improve mortality and decrease the incidence
of BPD
l prevent need for prolong intubation which
reduce the incidence of acquired subglottic
stenosis
23. Failure of CPAP therapy in RDS
l very low birth weight infant
l late application of CPAP
l severity of RDS
l associated disease e.g. sepsis,
hypotension
l infants with severe degree of extra-
pulmonary shunt
(Fox and coworkers, 1977)
24. CPAP in apnea of prematurity
l the application of low-level CPAP decrease
the incidence of apnea of prematurity
(compared to other forms of stimulation)
l improve oxygenation
l stimulation or inhibition of pulmonary reflexes
l alveolar stabilization
l mechanical splinting of airway; reduce
supraglottic resistance in both inspiration and
expiration
l some investigators recommended the early
use of CPAP as a preventive measure of
apnea of prematurity
25. CPAP in an infant with MAS
l pathology of meconium
aspiration
l atelectasis
l large airway obstruction
l V/Q abnormalities
l application of low-to moderate
level CPAP
l resolution of atelectasis
l stabilization of terminal
airway
l incidence of pneumothorax:
not increased
l precautions in case with PPHN
26. Adverse effects of CPAP
l pulmonary air leaks
l type of CPAP
l lung compliance
l gestational age
l gastric dilation and rupture
l hypotension
l increase pulmonary vascular resistance
l chronic lung disease ?
