Pulmonary Flashcards
COPD reading: What are some risk factors for Post-op Pulmonary Complications (PPC)?
Dyspnea with activity (quality of life assessment)
Inc age, dec functional status, BUN (high and low), type of surgery
History of cardiac failure, ASA 2+, COPD, renal failure, emergency surgery, smoker, alcohol use, steroid use
Positive cough test (repeated coughing after the first cough)
COPD reading: 90% of patients develop some degree of atelectasis during anesthesia. What predisposes a patient to compression atelectasis vs. reabsorption atelectasis?
Compression atelectasis results from patient positioning and loss of FRC, so obesity and large proportions of poorly aerated lung predispose patients to VQ mismatching
Reabsorption atelectasis results from low tidal volumes with high FiO2. Oxygen diffuses across the alveolar membrane causing a pressure difference that leads to airway collapse
COPD reading: Do PFTs have a role in predicting PPC?
No, they are only done before a lung resection or to classify the degree of lung impairment, they are also done to get a baseline lung function in myasthenia gravis patients.
COPD reading: Although cessation of smoking 48 hours before surgery decrease carboxyhemoglobin levels and cyanide levels, sputum production increases and symptoms of cough may worsen. To avoid PPC, smokers should quit ___ weeks before surgery (this also helps with wound healing and immune function.
8 weeks
COPD reading: A postbronchodilator FEV1/FVC ratio less than ___ confirms the presence of airflow limitation and is recommended for the diagnosis and assessment of severity of COPD
0.7
COPD reading: Should bronchodilators be continued before/during/after surgery for patients with COPD?
YES!!
COPD reading: What is a COPD exacerbation treated with?
Short acting inhaled Beta agonists with or without anticholinergics (ipratropium)
Systemic corticosteroids and antibiotics improve FEV1 and shorten recovery time.
COPD reading: What is the major preoperative goal for a patient with COPD?
Prevention of PPC with smoking cessation, bronchodilators, early recognition/treatment of infection or COPD exacerbation, and preoperative pulmonary conditioning for some high-stage COPD patients
COPD reading: Surgical patients with asthma have increased risk for perioperative complications, so what must be done to limit these complications?
Thorough pre-op evaluation including physical exam, management of any electrolyte abnormalities secondary to meds (B2 agonists), EKG to identify cardiac arrhythmias or abnormalities, continuation of asthma treatments, and treatment of other associated comorbidities (such as cor pulmonale)
COPD reading: If an asthma patient receives steroids within 6 months of surgery, what must be done peri-operatively?
They should receive systemic doses of steroids during the surgical period with a rapid wean within 24 hours postoperatively
COPD reading: What are the quick-acting and long-acting asthma medications?
Quick acting meds for acute exacerbations: B2 adrenergic agonists (albuterol) and corticosteroids can be used
Long-acting meds include long-acting B2 agonists (salmeterol), inhaled steroids, leukotriene modifier, inhaled anticholinergics, and IgE immunotherapy
These meds should be continued perioperatively
COPD reading: What is restrictive pulmonary disease characterized by?
Reduction of lung volume, both total and vital capacity
These patients are at risk for exaggerated pulmonary dysfunction postoperatively
COPD reading: What are pulmonary and extra-pulmonary conditions that lead to restrictive pulmonary disease?
Pulmonary: sarcoidosis, silicosis, TB, hypersensitivity pneumonitis, eosinophilic granulomatosis, pulmonary alveolar proteinosis, lung resection, atelectasis, ARDS, pulmonary edema
Extrapulmonary: obesity, skeletal/costovertebral deformities (scoliosis), sternal deformities (pectus excavatum), neuromuscular disorders, pneumothorax
COPD reading: What is the gold standard for diagnosing OSA? (obstructive sleep apnea)
Overnight polysomnography
COPD reading: Patients with OSA having increased risk of perioperative complications. More than ___% are undiagnosed, making the surgical preoperative assessment critical to optimized morbidity and mortality in these patients
80%
COPD reading: Before elective surgery, patients with OSA or at high risk of OSA should have what done?
Routine chemistry and CBC in conjunction with an EKG
If OSA is moderate to severe, ABG and rest radiograph should be considered to establish baseline levels
COPD reading: Although studies have not showed any increased risk for postoperative complications in the obese population, a physical exam that incorporates _____ is critical
A physical exam that incorporates a pulmonary exam, assessment of OSA risk, airway management, and functional status is critical
COPD reading: Because PPC occurs is over ___% of patients, preoperative diligence is imperative, especially in patients with chronic pulmonary disease, smokers, patients with COPD, asthma, restrictive lung disease, OSA, and obesity
25%
IRV + TV =
Inspiratory capacity + ERV =
Inspiratory capacity + FRC =
ERV + RV =
IRV + TV = Inspiratory capacity
Inspiratory capacity + ERV = VC (vital capacity)
Inspiratory capacity + FRC = TLC (total lung capacity)
ERV + RV = FRC
How many L are these normal values? TV, FRC, TLC, inspiratory capacity
TV 0.5 L
FRC 2.5 L (ERV 1.25 + RV 1.25)
TLC 5 L (another source says 6 L)
Inspiratory capacity 2.5 L (TV + IRV 2.0)
What do the conducting airways consist of?
Upper airways (nasopharynx, oropharynx) Larynx Lower airways (trachea, bronchi, terminal bronchioles: non-respiratory)
What do the gas exchange airways consist of?
Respiratory bronchioles
Alveolar ducts
Alveoli: epithelial cells, type 1 and type 2 alveolar cells
Type 1 vs. type 2 alveolar cells?
Type 1: gas exchange, we have mostly this type, maximizes surface area (size of a tennis court)
Type 2: surfactant production
What happens as we go up in generations of the airway?
Stiff at the beginning, as we move toward higher generations there is less cartilage
Generation 20 is where gas exchange begins, there are 26 generations
What layers does oxygen travel through to go from alveoli to blood?
Alveolus - surfactant layer - alveolar epithelium - basement membrane - interstitial space - capillary endothelium
Are inspiration and expiration active or passive?
Inspiration active
Expiration passive
What are the major muscles of inspiration? Assessory muscles of inspiration?
Major: diaphragm, external intercostals
Accessory: SCM (lift clavical and sternum) and scalenes (pull ribs up)
What are the accessory muscles of expiration?
Abdominal and internal intercostals
What is surfactant’s role in the alveoli in helping us breathe?
Surfactant decreases surface tension
LaPlace Law says tension = pressure x radius
Therefore, surfactant allows us to inflate all the alveoli
Under normal conditions, what drives ventilation? What drives ventilation in hypoxemic conditions?
CO2 tension normally
O2 tension in hypoxemic conditions
What are the four steps of gas transport? (oxygen to tissue)
- Ventilation of the lungs
- Diffusion of O2 from alveoli to capillary
- Perfusion of capillaries with oxygenated blood
- Diffusion of O2 from capillaries into cells
How do the pressures vary between the tissues and heart? PO2, PCO2, PH2O, PN2
Heart: PO2 104, PCO2 40, PH2O 47, PN2 569
Tissue: PO2 40, PCO2 46, PH2O 47, PN2 573
What factors contribute to the oxyhemoglobin dissociation curve shifting to the left vs. right? Hint: acid/base, temp, 2,3-DPG
Left shift INCREASES affinity- acute alkalosis, decreased PCO2, decreased temp, low 2,3-DPG, carboxyhemoglobin, methemoglobin, abnormal hemoglobin
Right shift DECREASES affinity- (think: running from a bear, you need the oxygen to be dropped off) acute acidosis, high PCO2, increased temp, high levels of 2,3-DPG, abnormal hemoglobin
How can you mathematically figure out the oxygen content?
O2 content = 1.34 x hematocrit x O2 sat (+ 0.003 x PO2; but this is an insignificant number)
What is hypoxic vasoconstriction? What is it caused by?
Caused by low alveolar pO2
Blood is shunted to other, well-ventilated portions of the lung to provide better V-Q matching
If hypoxia affects all segments of the lungs, pulmonary hypertension can result
Acidemia also causes pulmonary artery constriction
Compare PA (alveolar pressure), PV (venous pressure), and Pa (arterial pressure) in the 3 zones of the lung.
Zone 1: PA > Pa > PV
Zone 2: Pa > PA > PV
Zone 3: Pa > PV > PA
What does FEV1 test? What does FVC test?
Forced expirational volume-1 sec, Functional vital capacity
FEV1: How fast you can let air out in 1 sec. Should be 90%
FVC: all the way filled to all the way empty
These are types of spirometry tests
What changes in the aging population? IRV? TV? ERV? RV?
IRV decreases
TV doesn’t change
ERV doesn’t change
RV increases
How many weeks in fetal development do they get type 1 and type 2 alveolar cells?
Week 28
At week 24, they can store surfactant
At term, they can secrete surfactant as needed
Hypoxia vs. hypoxemia?
Hypoxia: low O2 content
Hypoxemia: low O2 tension
Hypoxemia can result in hypoxia but not necessarily the other way around
Kussmaul respirations vs. Cheyne-Stokes respirations?
Kussmaul: compensation for metabolic acidosis (ketoacidosis), breathing faster to blow off CO2
Cheyne-Stokes: alternating apnea and tachypnea (brain damage)