Respiratory distress syndrome: Pathology review

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Respiratory distress syndrome: Pathology review

Respiratory system


Respiratory distress syndrome: Pathology review

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A 1-day-old boy is brought to the intensive care unit from the nursery due to increased work of breathing. The patient was born at 31 weeks to a mother with a history of multiple preterm deliveries, polysubstance abuse and HIV. His temperature is 38°C (100.4°F), pulse is 215/min, respirations are 76/min, blood pressure is 60/41 mmHg, and oxygen saturation is 85% on room air. Physical exam shows tachypnea, nasal flaring, and subcostal retractions. Administration of supplemental oxygen and positive pressure ventilation improve the patient's oxygen saturation to 95%. Blood glucose is 95 mg/dL. Chest x-ray and laboratory results are shown below:  

Reproduced from: Wikipedia
Laboratory value  Result 
Blood Gases, Serum 
pH  7.23 
 PCO2  55 mmHg 
 PO2  30 mmHg 
Which of the following best describes the etiology of this infant’s disease process?


Two people are admitted to the emergency department.

Mike, a 55-year-old man, presents with shortness of breath, high fever, and cough.

A chest x-ray was ordered and it showed a right lower lobe infiltrate, which is suggestive of pneumonia.

He was then started on IV antibiotics but the following day Mike became hypoxic and hypotensive.

Because his hypotension didn’t improve despite intubation, IV fluids, and vasopressors, he is diagnosed with septic shock.

Next, a repeat x-ray detected newly-developed bilateral alveolar opacities, heart echography ruled out heart failure, and arterial blood gas analysis revealed a PF ratio of 109 milligrams Mercury.

Then there was Dona, an infant delivered by cesarean section at 36 weeks’ gestational age, with an Apgar score of 9 at birth.

A few hours after delivery, she develops tachypnea, chest wall retractions with nasal flaring, and tachycardia.

Aside from increased work of breathing, her physical examination findings are normal.

A chest x-ray was ordered and it showed diffuse reticulogranular ground glass appearance with air bronchograms.

Now, both people are in respiratory distress.

But first, a bit of physiology.

Normally, when you breathe in, the air reaches the alveoli, which are made up of two types of pneumocytes.

First, type I pneumocytes are thin, and have a large surface area that that facilitate gas exchange.

More important for the exams are the type II pneumocytes, which are smaller, thicker and have the ability to proliferate in response to lung injury.

They are in charge of making a fluid called surfactant which contains various phospholipids.

This lets it act like droplets of oil that coats the inside of the alveoli, decreasing surface tension, so if it’s missing, the alveoli will collapse.


Respiratory distress syndrome (RDS) is a respiratory condition in which the alveoli collapse due to the deficiency of the surface-active substance called surfactant. Collapsed alveoli make it difficult to breathe and get enough oxygen. Acute respiratory distress syndrome happens when inflammation causes diffuse alveolar injury and pulmonary edema. This edema can wash away the surfactant coating the alveoli to the point where it causes the alveoli to collapse. There is also neonatal respiratory distress syndrome, which mostly affects premature infants, whose lungs are not fully developed and lack enough surfactant.

Symptoms of respiratory distress syndrome include rapid breathing, grunting, and flaring of the nostrils while breathing, as well as cyanosis (bluish color of the skin) and difficulty feeding. All forms of respiratory distress can lead to respiratory failure and death if not treated promptly. Treatment includes providing respiratory support, and administering surfactants, especially in neonatal respiratory syndrome. The use of corticosteroids before delivery may also be considered to improve lung function in some cases.


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