Respiratory Distress Syndrome 1454 Uzair Siddiqi

ARDS Mechanism Alveolar capillary membrane damage (therefore higher vascular permeability) Diffusion is interrupted therefore hypoxemia Type I/II Pneumocytes damaged therefore surfactant lost (from oxygen derived free radicals, coag. cascade, neutrophils), type I pneumocytes also damaged Hyaline membrane formation from protein rich edema leaking into lungs (less compliance) Imbalance of pro/anti-inflammatory cells (eg IL-8 inflammatory, IL-10 anti-inflammatory) Alveoli cannot expand, possible fibrosis

Causes Sepsis Pulmonary Infections (mycoplasma, viral) Gastric aspiration Trauma Near drowning Irritants (oxygen toxicity, smoke, gases) Chemical injury (heroin, barbiturate OD) Pancreatitis Fat Embolism

Clinical Presentation Dyspnea/Tachypnea/Fatigue Cyanosis and hypoxemia Diffuse bilateral infiltrates Stiff and heavy lung Scarring in some cases Uneven functional distribution Decrease in mortality rate in US from 60% to 40% Behavioural changes Cough/Fever when pneumonia is the cause

Healing/Treatment Removal of exudate/dead cells and replacement (sodium transport needed, neutrophils removed) Type II pneumocytes give rise to type I TGF-B & PDGF stimulate fibroblast growth to help with healing Interstitial fibrosis will complicate recovery Underlying cause treatment & supportive oxygen (with PEEP), mechanical ventilation, steroids

Neonatal Resp. Distress Syndrome Lack of surfactant (therefore more surface tension) Collapse of air sacs and formation of hyaline membrane Problems with Lecithin:Sphingomyelin ratio (being less than 2, can be measured in amn. fluid) CAUSES: Prematurity (especially before 28 weeks) Cesarian delivery (lack of steroid induced stress) Maternal diabetes

Clinical presentation PDA from hypoxemia and necrotizing enterocolitis Grunting, tachypnea, nasal flaring, usage of accessory muscles to breathe Cyanosis & hypoxemia Ground-glass appearance of lung Supplemental O2 leads to free-radical injury and retinopathy Bronchopulmonary Dysplasia (BPD)

Morphology Solid, normal sized, airless, dark-red lungs Poorly developed and collapsed alveoli Hour-glass appearance of lungs on x-ray

Treatment & Prevention Delay labour until lung matures Corticosteroids to induce maturation Surfactant replacement therapy/oxygen

Robbins Pathology 8 th Ed Pg & BRS Pathology Pg Pathoma 3 rd Ed. Pg Crush The Step Pg Kaplan Pathology Lecture Notes 2013 Pg Essentials of Rubin’s Pathology 6 th Ed Pg & Goljan Rapid Review 4 th Ed Pg Lippincott’s Pocket Pathology 2 nd Ed Pg ARDS Pathogenesis: ARDS Research project: immune-cells-to-fight-lung-disease Signs of NRDS: REFERENCES/LINKS