RESPIRATORY DISTRESS IN INFANTS

AND CHILDREN

Presenters – Bethelhem Berhanu Betelhem Getahun.

Outline

• Introduction• Respiratory failure• Upper respiratory tract causes• Lower respiratory tract causes• Principles of Management

•Oxygenation•Elimination of carbon dioxide

Some terms…….• Ventilatory capacity is the maximal

spontaneous ventilation that can be maintained without development of respiratory muscle fatigue.

• Ventilatory demand is the spontaneous minute ventilation that results in a stable Pa CO2.

Ventilatory capacity > Ventilatory demand

Understanding Gas exchange

• V/Q : the ratio of the amount of air reaching the alveoli to the amount of blood reaching the alveoli.

• 1 liter of blood - 200 mL of oxygen; • 1 liter of dry air - 210 mL of oxygen.– Ideal value – Dry air – 1.05– Humidified air – 1• Reality??? – 0.8 – Not all alveoli are well ventilated, or

perfused.

• Atmospheric air – PO2 of 159 mmHg

• Alveolar air - PO2 of 104 mmHg– Why the difference?• Humidification• Constant absorption into pulmonary vessels.

• PaO2 – 85-100 mmHg• PaCO2 – 40mmHg = PAO2

• PAO2 – Calculated as – – PA O2 = FI O2 × (PB – PH2 O) – PA CO2/R

Where• Fi O2- fractional concentration of oxygen in inspired air –

(21% if atm. Air)• PB - barometric pressure (assumed to be 760mmHg)

• PH2 O - is water vapor pressure at 37°C

• PA CO2 is alveolar PCO2 (assumed to be equal to Pa CO2)

• Normal gradient of alveolar and arterial blood should be <10mmHg

Gas exchange ….

Definitions

• Respiratory Distress - refers to both difficulty in breathing, and to the psychological experience associated with such difficulty.

• Respiratory Failure – Is when the respiratory system fails in one or both of its gas exchange functions: oxygenation and carbon dioxide elimination.

Classifications

Gas involved

Hypoxemic(Type I)

Hypercapnic(Type II)

Hypoxemic Resp. Failure• Pathophysiologic mechanisms (two)– V/Q mismatch – Low V/Q• Decreased ventilation with normal perfusion

• Over-perfusion with normal ventilation

Airway or interstitial lung

disease

pulmonary embolism,

pulmonary HTN.

Hypoxemic contd…

• Shunt - Blood pathway which does not allow contact between alveolar gas and red cells

• Etiologies of Shunt physiology– Diffuse alveolar filling– Collapse / Consolidation– Abnormal arteriovenous channels– Intracardiac shunts

Poor or no response to

oxygen Therapy

Hypercapnic Resp. Failure

• an arterial partial pressure of carbon dioxide (PaCO2) greater than 50 mmHg.

• Less common• How to Differentiate???• It’s due to – Decreased minute ventilation – CNS, NMJ, chest w– Increase in dead space – Obstructive diseases– Increased CO2 production – fever, sepsis, seizure…

Normal PA-aO2

PA O2 = FI O2 × (PB – PH2 O) – PA CO2/R

In summary….

Clinical features of respiratory Failure

• Increased Respiratory Drive ● Increased rate/depth of

breathing ● Anxiety ● Breathlessness/dyspnea ● Retractions ● Accessory muscle use:

- Sternocleidomastoid - Intercostal - Alar nasae (nasal

flaring)

Decreased Respiratory Drive ● Decreased rate/depth of

breathing ● Lethargy ● Confusion

16

Why are kids different?• Obligate nose-

breathers• Tongue relatively

larger• Prominent tonsilar

and adenoidal lymphoid tissue.

• Narrow airway• Little cartilagenous

support.

• Increased metabolic demands

• Less number and elasticity of alveoli.

• Lower FRC.• Diaphragm– Muscle fibers

more vulnerable to fatigue

• Chest wall– Ribs more

horizontal

LUNG RESPIRATORY PUMP CENTRAL AIRWAY OBSTRUCTION CHEST WALL DEFORMITY Tracheomalacia Kyphoscoliosis Subglottic stenosis Diaphragmatic hernia

Epiglottitis Flail chest

Croup Eventration of diaphragm

Vocal cord paralysis Prune-belly syndrome Foreign body aspiration Pulmonary hypoplasia Vascular ring Adenotonsillar hypertrophy BRAINSTEM Near-strangulation Sleep apneaPERIPHERAL AIRWAY OBSTRUCTION Central hypoventilation

Bronchiolitis Poisoning

Asthma Trauma

Aspiration Central nervous system infection Cystic fibrosis SPINAL CORD Bronchomalacia TraumaDIFFUSE ALVEOLAR DAMAGE Poliomyelitis (acute respiratory distress syndrome) Werdnig-Hoffmann disease Sepsis NEUROMUSCULAR

Pneumonia Postoperative phrenic nerve injury

Pulmonary edema Birth trauma Near-drowning Infant botulism Pulmonary embolism Guillain-Barré syndrome Lung contusion Muscular dystrophy Shock Systemic inflammatory response syndrome

Common causes of Resp. Failure in children

Upper respiratory tract

Lower Respiratory Tract PneumoniaBronchial asthmaBronchiolitis

CroupEpiglottitisForeign body aspiration

Croup• Viral croup, AKA laryngotracheobronchitis– M. pneumoniae – isolated from pts with croup

• the most common form of acute upper respiratory obstruction.

• Common b/n ages 5 months and 3 years– Peak age 2 years– M>F

• Parainfluenza virus – 75%– Influenza A&B, RSV, measles

Clinical features

• Barking cough • Stridor• Low grade fever• Hoarseness of voice

• Signs of respiratory distress• Tachypnea• Coryza• Inflamed Pharynx• Cyanosis

Worse at night

Resolve within a week

Aggravated by crying

Diagnosis

• Is clinical – X-ray is not a requirement– Consider X-ray in patients with atypical

presentation or clinical course• On X-ray

Hypopharnyx

Narrow air column

Trachea

Steeple sign

Epiglottitis

• Inflammation of the epiglottis and adjacent supraglottic structures.

• dramatic, potentially lethal condition• Common – b/n 6 months to 3 years of age. • Danger of airway obstruction - medical

emergency.

Clinical features

• High fever• Sore throat• Dyspnea• Swallowing difficulty• Drooling• Tripod Position• Stidor – late sign

Diagnosis• diagnosis requires visualization of a large, “cherry red” swollen epiglottis by laryngoscopy.

• Lateral neck radiograph ( "thumb print" sign)

Foreign body Aspiration• Toddler through preschool age common– children <3 years 73% %

• Commonly aspirated – nuts (1/3), popcorn, small parts of toys….

• Feared complication – complete airway obstruction. – Unable to speak or cough

• Three stages of symptoms (partial)– Initial event – sudden, violent cough, choking,

gagging.– Asymptomatic interval - FB becomes lodged,

reflexes fatigue and irritation symptoms subside. • Common reason for delayed diagnosis and overlooked

FB.

– Complications – Obstruction, erosion or infection• Hypoxia, hemoptysis, Fever, atelectasis

Diagnosis

• P/E – Respiratory distress. Inspiratory stridor (central airway obstruction)– Wheezing – small airway obstruction– If beyond the carina, usually asymmetric noises

• Hyperinflation & air-trapping of the affected lobe(s) is typical– Best seen with X-ray taken at expiration

• Bronchoscopy – Diagnostic and therapeutic

Thank you!