RESPIRATORY DISTRESS
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Transcript of RESPIRATORY DISTRESS
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!