T4 - Restrictive Lung Disease Flashcards
Restrictive lung disease affects these two things…
Lung expansion and compliance
RLD is typically r/t connective tissue diseases, environmental factors, pulmonary fibrosis, conditions that increase alveolar or interstitial fluid, and diseases that limit excursion of the chest/diaphragm
What is the hallmark of RLD?
Inability to increase lung volume in proportion to an increase in alveolar pressure
…these disorders lead to reduced surface area for gas diffusion, causing V/Q mismatching and hypoxia
As lung elasticity worsens, pts become symptomatic d/t (3)
Hypoxia, inability to clear secretions, and hypoxia
Effects of RLD on FEV, FEV1, and FEV1:FVC ratio
↓FEV
↓FVC
↔/↑FEV1:FVC ratio
…also, a reduced diffusion capacity for carbon monoxide (DLCO)
Effects of RLD on lung volumes
All lung volumes are decreased, especially total lung capacity (TLC)
Expected changes in the volume flow loop
What is the principal feature of RLD, represented in spirometry
TLC
TLC is used to classify RLD as mild, moderate, or severe. What are the % of predicted value ranges?
Mild: TLC 65-80%
Moderate: TLC 50-65%
Severe: TLC <50%
List of RLD causes
What is the cause of pulmonary edema? Acute pulmonary edema?
Interstitial fluid leakage into the interstitium & alveolar space
Acute pulmonary edema can be c/b increased capillary pressure or by increased capillary permeability
…both lead to “capillary stress failure”
What characteristics does a CXR showing pulmonary edema have?
Bilateral, symmetric perihilar opacities
…butterfly fluid pattern, more commonly seen w/increased capillary pressure than increased capillary permeability
Diffuse alveolar damage, typically present with increased-permeability pulmonary edema, is associated with _______
ARDS
Pulmonary edema c/b increased capillary permeability is characterized by ↑ or ↓ concentration of protein and secretory products in the edema fluid.
↑
With what kinds of heart failure (2) can cardiogenic pulmonary edema be present?
Acute & decompensated
What are the characteristics of cardiogenic pulmonary edema? (4)
Dyspnea
Tachypnea
Elevated cardiac pressures
SNS activation
What conditions increase the risk of cardiogenic pulmonary edema? (vague answer)
Conditions that acutely increase preload s/a acute aortic regurgitation and acute mitral regurgitation
Conditions that increase afterload or SVR s/a LV outflow tract obstruction, mitral stenosis, and reno-vascular HTN
Negative pressure pulmonary edema (post-obstructive pulmonary edema) results after the relief of an acute upper airway obstruction; what are the causes? (6)
Laryngospasm
Epiglottitis
Tumors
Obesity
Hiccups
OSA
…onset after relief of obstruction ranges from a few minutes to 2-3hrs
Treatment for negative pressure pulmonary edema
Supplemental O2 and maintenance of a patent upper airway, this form of pulmonary edema is typically self-limited
Mechanical ventilation may occasionally be needed for a brief period
Common signs of negative pressure pulmonary edema
Tachypnea
Cough
Failure to maintain SpO2 >95%
….can be confused with aspiration or pulmonary embolism
Pathogenesis of negative pressure pulmonary edema
Spontaneous ventilation is necessary to create negative pressure, drawing in fluid. High negative intrapleural pressure is developed against an obstructed upper airway, and negative intrapleural pressure decreases interstitial hydrostatic pressure, increases venous return, and increases left ventricular afterload. These factors produce acute pulmonary edema by increasing the transcapillary pressure gradient.
Pathogenesis of neurogenic pulmonary edema
Develops in a small fraction of acute brain injury patients, Occurs minutes-hours after CNS injury and may manifest during the period period. Massive outpouring of SNS impulses from the injured CNS that results in generalized vasoconstriction and blood volume shift into the pulmonary circulation. The increased pulmonary capillary pressure c/b translocation of the blood volume leads to the transfer of fluid into the interstitium and alveoli.
Pathogenesis of re-expansion pulmonary edema (REPE)
The rapid expansion of a collapsed lung may lead to REPE
The risk of REPE after relief of a pneumothorax or pleural effusion is related to:
- amount of air/liquid that was in the pleural space (>1 increases risk)
- the duration of collapse (>24 hrs increases the risk)
- speed of re-expansion
Treatment for REPE
Supportive care