The Surgical Review- Thoracic Flashcards
Three zones of the lung?
- Conducting zone: first 16 divisions, ciliated epithelium + mucus secreting goblet cells
- Transitional zone: 17-19th division
- Respiratory zone
which type of alveolar cells produce surfactant and what is surfactant?
type II
dipalmitoyl phosphatidylcholine- reduces alveolar surface tension and prevents alveolar collapse
what components does spirometry measure?
Tidal volume (VT), vital capacity (VC), inspiratory reserve volume (IRV), and expiratory reserve volume (ERV)
what is tidal volume and what is a normal?
volume of air inspired or expired during normal breathing, ~7mL/kg in average adult
what is vital capacity?
the amount of air that can be expelled from the lungs during a maximal forced expiration after a maximal forced inspiration
using PFTs/spirometry, whats the difference between obstructive and restrictive lung disease?
Obstructive: FEV1/FVC ratio is decreased (
what are the two vascular networks of the lung?
- Bronchial circulation- arising from the descending aorta, supplies the conducting zone of the lung and drains into pulmonary venous system
- Pulmonary circulation - arising from R ventricle, coats alveoli for gas exchange
how do the pulmonary vessels differ from the systemic arterial supply?
thinner walls with less elastin and smooth muscle resulting in:
- lower pressure
- less resistance
- increased capacitance
what are the zones of the lung and relationships of PA, Pa, Pv
Zone I: PA > Pa > Pv, apex, alveolar dead space, no blood flow (ventilated but not perfused)
Zone II: Pa > PA > Pv, middle, pressure flow driven by difference between alveolar and arterial pressure
Zone III: Pa > Pv > PA, base of lung, pressure for flow is the difference between arterial and venous pressures
what is ficks law of diffusion?
V gas = A x D x (P1-P2) /T
A= area available for diffusion, D = diffusion coefficient, P = pressure gradient, T = thickness of barrier
what are the most common causes of hypoventilation seen in surgical population?
- Respiratory depression 2/2 general anesthesia or pain medications
- Respiratory mm dysfunction 2/2 paralytic meds
- Splinting secondary to pain
- Traumatic injuries ie flail chest
- Upper airway obstruction from tumor invasion
what is the key diagnostic feature of hypoventilation?
hypercarbia!! because PCO2 is inversely related to the volume of alveolar ventilation (halving alveolar ventilation results in a doubling of arterial PCO2)
what are shunts?
lung that is perfused but not ventilated, can see in a-v fistulas, congenital defects etc
what is the only cause of hypoxemia that does not improved with the administration of 100% oxygen?
shunts!
what is the most common pathologic organism in the lung?
mycobacterium TB
treatment of mycobacterium TB?
Isoniazid, Rifampin, ethambutol, pyrazinamide
when do you operate in mycobacterium TB infections of lung? (6)
- positive sputum cx plus cavitary lung lesions after >5months of treatment with 2 or more drugs
- Severe/recurrent hemoptysis
- Bronchopulmonary fistula not responsive to chest tube
- persistent empyema
- a mass found in the area of the lung infected
- disease caused by mycobacterium avium intracellulare
treatment of bronchiectasis?
antibiotics, cessation of smoking, pulmonary toilet
when is surgical intervention warranted in patients with lung abscess?
when a cavity larger than 2cm persists for longer than 8 weeks after antimicrobial therapy, or in setting of persistent bacteremia, hemoptysis, or neoplasm is suspected
what is the definition of massive hemoptysis?
greater than 500cc of blood loss from the lung over 24hrs
what do u have to be worried about when doing an angiographic embolization of lung?
quadriplegia, as the bronchial circulation often contributes to the blood supply of the spinal cord
most common lung mass benign
hamartoma
how do u distinguish a hamartoma from a lung cancer?
presence of a fat density within the nodule seen on CT
environmental toxins related to lung cancer? 3
asbestos, chromium, radon gas
