Mid-Term Exam - Part 2, Pathophysiology Flashcards
(37 cards)
a) Hypoxemia
b) Hypoxia
c) Anoxia
a) low PaO2
b) low O2 in the tissues resulting from inadequate O2 delivery to meet tissue oxidative requirements.
c) absence of O2, the extreme of hypoxia
Causes of Hypoxemia
Respiratory: reduced inspired oxygen tension, alveolar hypoventilation, impairment of diffusion, ventilation-perfusion mismatching.
Other systems: blood volume loss, anemia, carbon monoxide poisoning (240x more binding capacity to Hgb), hypothermia
Signs / Sx of Hypoxemia
cyanosis
acute cerebral hypoxia (impaired judgement, confusion, coma, death)
chronic cerebral hypoxia (fatigue, apathy, reduced attention, drowsiness)
cardiac arrythmia
pulmonary artery vasoconstriction
a) hypercapnia
b) hypocapnia
a) increase in PaCO2 (hypoventilation > 45mmHg
b) low PaCO2 (hyperventilation <35mmHg)
normal = 35-45mmHg
Signs / Sx of Hypercapnia
increased HR and BP dizziness Headache (HA) confusion or loss of consciousness muscle twitching and tremor irritability CO2 Narcosis: a condition of confusion, tremors, convulsions, and possible coma that may occur if blood levels of carbon dioxide increase to 70 mm Hg or higher.
Signs / Sx of Hypocapnia (Hyperventilation Syndrome)
lightheadedness fatigue irritability inability to concentrate tingling impaired consciousness
Restrictive Lung Dysfunction
an abnormal reduction in pulmonary ventilation. lung expansion is diminished. the volume of gas moving in/out of the lungs is decreased.
flow rates are often maintained, while volumes are less
Obstructive Lung Dysfunction
diseases of the respiratory tract which produce an obstruction to airflow, and can ultimately affect the mechanical function and gas exchanging capability. flow rates impaired. tissue damage, airway destruction.
i.e. chronic bronchitis, emphysema, asthma, bronchiectasis
though a disease may present with more obstructive or restrictive pattern, there are components of both patterns in most diseases.
Restrictive Lung Dysfunction: Clinical Manifestations: Signs
Tachypnea
Hypoxemia ( < 80mmHg), V/Q mismatching
Decreased breath sounds (dry inspiratory rales (velcro crackles)
Decreased lung volumes
Decreased diffusing capacity
Cor pulmonale ( alteration in the structure and function of the right ventricle caused by a primary disorder of the respiratory system)
Restrictive Lung Dysfunction: Clinical Manifestations: Symptoms
Dyspnea (shortness of breath (SOB))
Dry, non-productive cough
Emaciation (SOB when eating, high fat diet)
Restrictive Lung Dysfunction: pathogenesis
1) chest wall or lung compliance reduced = increased transpulmonary gradient needed just to expand the lungs
2) eventually causes all lung volumes and capacities to be reduced.
3) work of breathing is increased (increased airway resistance, increased flow rates, decreased lung/chest wall compliance)
Identifying RLD by Spirometry
Total Lung Capacity (IRV + TV + ERV + RV) and Vital Capacity (ERV + TV + IRV) are the two most common measures used to identify RLD.
Decreases in TLC and FRC (ERV + RV) are a direct result of a decrease in lung compliance.
RLD: more pressure, less volume
RLD Compensatory Strategies
to overcome the decrease in pulmonary compliance, the RR is usually increased.
Accessory muscles of inspiration are recruited to assist in chest wall expansion when at rest of at lower activity level.
with RLD the % of VO2 required to support the work of breathing can be 25% or more (normally 5%).
Treatment RLD; permanent or progressive
i.e. pulmonary fibrosis supportive measures: antibiotic therapy measures to promote adequate ventilation supplemental oxygen prevention of accumulation of pulmonary secretions nutritional support flexibility/posture more prone to infection, secretion accumulation
Treatment RLD; acute and reversible, or chronic and reversible
i.e. guillian-barre syndrome, myasthenia gravis
aimed at specific corrective interventions as well as supportive measures.
OLD: pathogenesis
1) altered expiratory flow rate
2) increased residual volume
3) increased airflow resistance
4) loss of elastic recoil
5) increased work of breathing
OLD: clinical manifestations: Signs
hypoxemia
increased production of mucous/impaired mucous clearance
inflammation of the mucosal lining of the bronchi and bronchioles
mucosal thickening
spasm of the bronchial smooth muscle
pulmonary hypertension
polycythemia (blood more viscous, clots spO2 is low)
Cor Pulmonale
hyperinflation of lungs - deep breathing makes them feel worse
OLD: clinical manifestations: Symptoms
chronic cough
expectoration of mucus
wheezing
dyspnea on exertion (DOE)
OLD: Work of Breathing
respiratory muscles must work harder to overcome the increased airway resistance
diaphragm excursion may be limited due to hyperinflation of the lungs (flatter shape, inability to contract strongly)
alveolar ventilation is reduced
alveolar-capillary membrane surface area may be reduced
force air out of the lungs = a lot of abdominal contraction
OLD: Classification of location of airway obstruction (3)
a) bronchi or airways with cartilage in their walls (>2mm diameter)
b) bronchioles or airways without cartilage in their walls (<2mm diameter)
c) lung parenchyma (alveolar units); portion of lung involved in gas exchange
OLD: Alteration in Airflow
narrowing of the bronchial lumen: increased resistance to airflow
loss of normal elastic recoil of lung tissue = tendency for the airways to collapse hyperinflation
Emphysema
an alveolar or parenchyma disease. an abnormal and permanent enlargement or air spaces distal to the terminal nonrespiratory bronchioles, accompanied by destructive changes of the alveolar walls. loss of elastic recoil, excessive collapse of the airways on exhalation and chronic airflow obstruction.
Pulmonary Fibrosis: description
RLD: an inflammatory process involving all the components of the alveolar wall that progresses to gross distortion of the lung architecture. first inflammatory, then scar and become fibrotic.
Bronchiectasis
a permanent abnormal dilation and distortion of one or more bronchi that is caused by destruction of the elastic and muscular components of the bronchial walls.
Etiology: cystic fibrosis, bronchial obstruction, etc
