Chapter 21 Flashcards
Tidal volume
The amount of air inspired or expired during nl respiration
FRC
The amount of air contained in the lungs after nl expiration
VC
The amount of air exhaled following maximal inspiration and forced expiration
RV
The amount of air remaining in the lungs after maximal expiration
FEV1
The volume of air exhaled in 1 second with a maximum expiratory effort
Criteria for operative risk for pulmonary resection
Preoperative FEV1:
>40% predicted: little increased risk
30-40% predicted: increased risk of pulmonary complications
<30% predicted: prohibitive risk
Etiologies of hypoxemia
Hypoventilation
Diffusion gradient
V/Q mismatch
Presence of a new solitary nodule in a pt with smoking hx
Must be assumed to be a lung CA until proven otherwise
What is the most common cause of cancer-related death in men and women
Lung CA
____ of lung cancer is non-small cell lung CA
80%
What percentages of NSCLC are resectable?
5-yr survival?
20%
70%
What is the cornerstone of therapy for stage I and stage II dz for NSCLC?
Surgical resection
What has demonstrated a clear benefit in stage II and III dz for NSCLC?
Adjuvant therapy
Who are considered not to be operative candidates, particularly with contralateral positive nodes?
Stage IIIB
What are signs of inoperability in lung CA?
Bloody pleural effusion
Horner syndrome
SVC syndrome
Distant metastases
What is the central purpose of respiration?
Deliver oxygen to erythrocytes and clear carbon dioxide
This enables the body’s cells to undergo aerobic metabolism to efficiently produce ATP
What does gas exchange in respiration consist of?
Ventilation
Blood-gas interface
Perfusion
Ventilation
The process by which atmospheric air travels to the alveoli
Blood-gas interface
The site of gas exchange
Perfusion
Whereby blood passes through this interface
How is the pressure gradient required for air movement generated?
By the primary and accessory respiratory muscles
What is the upper airway composed of?
Mouth
Pharynx
Larynx
What is the conducting zone of the lung composed of?
The trachea and the first 16 generations of the airways
This zone is the anatomical dead space because there is an absence of alveoli
What comes after the conducting zone?
17th-19th generations: respiratory bronchioles (transition zone)
Generations 20-23- lined with alveolar ducts and sacs (respiratory zone)
Composition of conducting airways distal to the pharynx
Have cartilaginous walls with minimal smooth muscle
Lined with ciliated epithelium interspersed with mucus-secreting goblet cells
Smokers and pathology
Demonstrate abnormalities in both mucous production and ciliary motility that contribute to their difficulties with secretion clearance
Bronchiectasis
A condition in which the bronchi are dilated and a loss of ciliary action occurs
Secretions pool and can become chronically infected, a situation that may be associated with hemoptysis
What is the transition zone composed of?
Membranous and terminal bronchioles
They do not contain cartilage and are innervated by the autonomic nervous system.
Histologic morphology of the respiratory zone
Contains 300 million alveoli
What is the critical component of the alveoli that is integral for movement?
The elastin that is embedded within the basal lamina in the alveolar septal interstitium
What are the two major types of alveolar epithelial cells?
Type I cells: the major lining cells, large, flat, squamous cells with cytoplasmic extensions and are primarily responsible for gas exchange
Type II cells: Granular pneumocyte that are thicker and are responsible for producing surfactant
Where are surfactant levels decreased?
Respiratory distress syndrome
Acute pancreatitis
Smokers
How is ventilation achieved?
Achieved by air movement to and from the alveoli
Accomplished by a decrease in intrathoracic pressure relative to the atmosphere when the diaphragm contracts and the thoracic cavity expands
What occurs when large volumes of air are required?
The external intercostal muscles contract, which further expands the thoracic cavity
How is ventilation assessed?
By the measurement of the partial pressure of arterial carbon dioxide
What is the driving pressure for airflow through the entire system?
The difference between the alveolar pressure and pressure at the airway opening (atmospheric pressure)
What are the components of alveolar pressure?
Elastic recoil pressure and the pleural pressure
Hypoxemia
Clinically manifested as low oxygen tension in the arterial blood Typically results from: -Hypoventilation -Diffusion gradients -Shunt -Ventilation-perfusion mismatch
Causes of hypoventilation
Drugs
Mechanical impairments of the chest wall
Paralysis of the respiratory muscles
What can cause arterial hypoxemia?
Any interstitial lung process such as collagen vascular dz, sarcoidosis, and idiopathic interstitial fibrosis
Shunt
The fraction of blood that enters the systemic arterial system without passing through a ventilated portion of the lung
Causes of shunt
Occur due to intracardiac communications such as in congenital heart disease, arteriovenous malformations of the lung, lung consolidation, and vasodilators such as nitroprusside
