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PATHOPHYSIOLOGY

Neonatal RespiratoryDistress Syndrome

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PREMATURITY

Surfactant

Deficiency

Structurally

Immature LungsAtelectasis

V/Q Mismatch Hypoventilation

Hypoxemia & Hypercarbia

Acute Phase Chronic Phase

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Respiratory &

Metabolic Acidosis

Pulmonary

Vasoconstriction

Impaired Endotheliaand Epithelial

Integrity

ProteinaceousExudates

Respiratory DistressSyndrome (RDS)

High Fi02 & Baro or Volutrauma

Inflammation Cell

Influx

Antioxidant

Release

Cytokine Release Free Radicals

Lung Injury

Chronic Lung Disease or Bronchopulmonary

Dysplasia

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Atelectasis- the collapse or closure ofthe lung resulting in reduced orabsent gas exchange. It may affectpart or all of one lung.It is a conditionwhere the alveoli are deflated, asdistinct from pulmonary consolidation.

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the VENTILATION/PERFUSION RATIO(or V/Q ratio) is a

measurement used to assess the efficiency andadequacy of the matching of two variables: It isdefined as: the ratio of the amount of air reachingthe alveoli to the amount of blood reaching thealveoli.

"V" ventilationthe air that reaches the alveoli

"Q"perfusion the blood that reaches the alveoliThese two variables constitute the maindeterminants of the blood oxygen concentration.

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Hypoxemia - an abnormally low level of oxygen in

the blood. More specifically, it refers to oxygendeficiency in arterial blood. Hypoxemia has manycauses, often respiratory disorders, and can causetissue hypoxia as the blood is not supplying enoughoxygen to the body.

Hypercarbia - abnormally high level of carbondioxide in the circulating blood

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Respiratory acidosis -is a medical condition in which

decreased ventilation (hypoventilation) causesincreased blood carbon dioxide concentration anddecreased pH (a condition generallycalled acidosis).

Metabolic acidosis- is a condition that occurs whenthe body produces too much acid or whenthe kidneys are not removing enough acid from thebody.

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Fraction of inspired oxygen (FiO2) - is the fraction orpercentage of oxygen in the space being measured.

Medical patients experiencing difficulty breathing areprovided with oxygen-enriched air, which means a higher-than-atmospheric FiO2. Natural air includes 20.9% oxygen,which is equivalent to FiO2 of 0.21. Oxygen-enriched airhas a higher FiO2than 0.21, up to 1.00, which means 100%

oxygen.[1]FiO2is typically maintained below 0.5 even withmechanical ventilation, to avoid oxygen toxicity.

Volutrauma - is essentially damage to the lung caused byoverdistention by a mechanical ventilator set for anexcessively high tidal volume; resulting in a syndrome

similar to adult respiratory distress syndrome. Volutrauma isseparate from Pulmonary barotrauma because themechanism of injury is excessive volume (volutrauma),instead of pressure (barotrauma).

http://en.wikipedia.org/wiki/Fraction_of_inspired_oxygenhttp://en.wikipedia.org/wiki/Fraction_of_inspired_oxygenhttp://en.wikipedia.org/wiki/Fraction_of_inspired_oxygenhttp://en.wikipedia.org/wiki/Fraction_of_inspired_oxygen

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Bronchopulmonary dysplasia (BPD - formerly chronic lung

disease of infancy) is a chronic lung disorder that is mostcommon among children who were born prematurely.Bronchopulmonary dysplasia results in significant morbidityand mortality. Bronchopulmonary dysplasia is more commonin infants with low birth weights and those who received

prolonged mechanical ventilation to treat respiratory distresssyndrome. The definition of bronchopulmonary dysplasia(BPD) has continued to evolve since 1967 when the disorderwas first described in publication, which resulted from effectsof oxygen and mechanical ventilation in premature infantswith severe respiratory distress syndrome (RDS). This is due tochanges in the population at risk.