CPAP – A “GENTLE” VENTILATION

DR ASHOK MODIMD, DNB, MRCP(UK)

CONSULTANT NEONATAL INTENSIVIST

Bhagirathi Neotia Woman & Child Care Centre

CONTENTS

• Introduction• Historical aspects• How it works• Methods• Indications• WeaningWeaning• Adverse effectsAdverse effects

Introduction

• Respiratory distress in a just born baby- bad news! – For doctors – Inconvenience, complications(BPD)– More so for family – death, handicap, cost

• Solution – CPAP– Doctors – convenient, less likely to go wrong– Family – baby saved, low cost

• Do I need to tell more?– Continuous distending pressure to upper & lower

airways, spontaneously breathing, throughout

What is CPAP ?

A technique of airway Management A technique of airway Management in which :- in which :-1. Positive intrapulmonary pressure is 1. Positive intrapulmonary pressure is

applied artificially to the airways , applied artificially to the airways , whereby Distending Pressure is whereby Distending Pressure is created in the Alveolicreated in the Alveoli

2. Spontaneously breathing baby 2. Spontaneously breathing baby

3. Throughout the respiratory cycle3. Throughout the respiratory cycle

Historical aspects

• Harrison – 1st increased alveolar pressure during expiration in RDS; Abolition of the grunt in RDS – deterioration

• Gregory et al(1971) – used CPAP 1st in spontaneously breathing neonate in RDS

• Last 3 decades – long way to newer devices with better knowledge of physiology & bio-physics

What does it do?

• Prevents alveolar atelectasis, enhances & maintains FRC

• Decreases total airway resistance• Regularises breathing pattern• Improvement in surfactant

metabolism• Splints chest wall, airways & Pharynx• Reduces work of breathing

What does it do?

• Results in reopening of collapsed/unstable alveoli - – Increased surface area for gas

exchange– Preserves surfactant esp if applied early– Prevents Intrapulmonary shunting

• Net result improved oxygenation & ventilation

How to deliver CPAP

• Delivery of continuous positive airway pressure requires 3 components –

1. Flow circuit(warm & humidified)

2. An airway interface

3. A positive pressure system

Airway Interface

• Single nasal prongs• Binasal prongs(Short & Long)• Nasopharyngeal prongs• Endotracheal tube• Head boxes, nasal cannulae, face

masks• Short binasal prongs most effective,

least invasive

Positive pressure system

• Fluid column(Bubble CPAP)• Resistance applied at the expiratory

valve e.g Draeger / Ventilator• Pressure generation at nasal level• CPAP generation in the immediate

vicinity of nasal airway by converting kinetic energy e.g Infant flow driver

DEVICES

• Infant Flow Driver –unique fluid mechanics(fluidic flip action)

• Bubble CPAP – oscillatory vibrations

• Infant Ventilator with CPAP mode• Which is the best?

Optimal pressure

• No compelling Data• Traditional 4 –6 cm of water• However some studies as high as

10 cm H2O• Tailored to baby’s needs• Increments by 1 cm of water• Guided by CXR

INDICATIONS

• Mild to moderate RDS• Apnoea of prematurity• After extubation• Alternative to mechanical ventilation ( INSURE)• Presence of poorly expanded or

infiltrated lung fields on CXR• Tracheomalacia or abnormalities of

lower airways

CONTRA-INDICATIONS

• Definite need for intubation & Ventilation– Upper airway anomaly e.g choanal atresia,

cleft lip & palate, TOF– Cardiovascular instability & impending arrest– Unstable respiratory drive– Untreated CDH– When CPAP is failing

• Bronchiolitis

Monitoring & Care

• Minimal handling/Sedation• Nasal prongs of right size in

place(FIXATION)• Orogastric tube• Care of the nares• Change of posture• Vitals & Continuous pulse oximetry• Blood gas, haematological, radiological &

biochemical monitoring

Is CPAP Helping?

• Reduction in respiratory rate• Stabilization or reduction in Fio2• Resolution of grunting• Reduction in degree of sternal &

intercostal recession

When is CPAP failing

• Recurrent apnoeic attacks• Spontaneous episodes of

desaturation• Increasing oxygen requirements • Worsening respiratory distress• Agitation not relieved by simple

measures • Worsening blood gases

WEANING

• Once baby very stable with minimal respiratory distress, normal blood gas & improving CXR

• Fio2 gradually weaned to 40 – 50%• Then pressure decreased in steps

of 1 cm of water until 3 – 4 cm

Not without its complications

• Do not take CPAP lightly!• Pulmonary air leaks• Excessive pressure- compromise o2• Abdominal distension• Hypotension• Local – excoriation, scarring,

deformity

Setting an simple CPAP

To conclude

• Gentle & poor man’s ventilation• Easy to set up & minimal training• Save babies with RDS in developing

countries vs headbox O2• Lots of unanswered questions yet –

– Optimal device– Ideal pressure