ALTERATIONS IN PAEDIATRIC RESPIRATORY FUNCTION

ALTERATIONS IN PAEDIATRIC RESPIRATORY FUNCTION

1. ACUTE RESPIRATORY DISTRESS SYNDROME

   • definition
     • life-threatening lung condition
     • form of breathing failure
     • swelling of tissue in the lungs due to inflammatory process and build up of fluid in the alveoli
       • This leads to low blood oxygen levels and alveolar injury
     • similar to infant respiratory distress syndrome, but the causes and treatments are different
       • can develop in anyone over the age of one year old
     • ARDS is characterized by its acute onset, bilateral pulmonary infiltrates, severe hypoxemia, and pulmonary edema of noncardiac origin
   • causes
     • Chest trauma; Aspiration; Breathing smoke, chemicals, or salt water; indirect lung injury
   • pathophysiology
     • EXUDATIVE PHASE
       • immune-cell-mediated destruction of the barriers of the alveolar epithelial–inter stitial–endothelial complex
         • causing a flood of plasma to enter the interstitial space
           • followed by hyaline membrane formation leading to alveolar collapse
       • decreased pulmonary compliance; arterial hypoxaemia; severe dyspnoea and tachypnoea;
       • initial phase where alveolar macrophages are activated in high inflammatory stage due to lung injury
     • PROLIFERATIVE PHASE
       • marks attempts at recovery, with restoration of the type II alveolar cell population
         • subsequent differentiation into type I alveolar cells
       • Regeneration of a functioning epithelial layer allows the clearance of exudative fluid out of the interstitium, and any remaining debris is cleared by inflammatory cells
       • recovering pulmonary compliance; increased alveolar dead space; refractory pulmonary hypertension
     • FIBROTIC PHASE
       • develops inconsistently, and comprises of the failure to remove alveolar collagen
       • the development of cystic changes, limiting functional recovery
       • related to the need for prolonged mechanical ventilation and increased mortality
   • clinical manifestations
     • labored and rapid breathing; muscle fatigue and general weakness; low blood pressure; discolored skin or nails; a dry, hacking cough; a fever; headaches; a fast pulse rate; mental confusion

2. RESPIRATORY FAILURE

   • also called "respiratory insufficiency"
   • the lungs are no longer functioning correctly and there is inadequate gaseous exchange
     • causes abnormal levels of O2 and Co2 in the vascular system
     • poor ventilation of the alveoli
     • could be due to signal interruption to the alveoli due to, for example, narcotic overdose
   • there are different phases, each with their own clinical manifestations
     • initial signs/stage
       • - there is compensation from the child to overcome the airway block and O2 deficiency
       • behaviour and vital data indicate compensatory mechanisms and beginning hypoxia
       • restlessness tachypnoea tachycardia diaphoresis
     • early decompensatory phase
       • accessory muscle use to assist O2 intake
       • hypoxia persists and breathing efforts now waste more O2 than it obtains
       • nasal flaring retractions grunting wheezing anxiety headache hypertension confusion
     • severe hypoxia and intermittent respiratory arrest
       • the O2 deficit is overwhelming and beyond spontaneous recovery
       • cerebral oxygenation = dramatically affected and central nervous system changes are ominous
       • dyspnoea bradycardia cyanosis stupor coma

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