Pulmonary Flashcards
What information do you want to gather during the history of a pulmonary pt?
- Baseline pulmonary function
- exercise tolerance
- dyspnea
- orthopnea
- smoking
- OSA
- chronic lung disease
- severity
- medications
- recent hospitilizations
- frequency of exacerbations
- effective treatments
- Acute lung disease
- recent URIs
- antibiiotics
- current symptoms
- Previous anesthesia
- complications?
- Medical clearance
- evaluate for current status
- labs/diagnostic tests
What are the components of physical assessment?
- inspection/ observation
- auscultation
- palpation
- percussion
What can you observe about your pts pulmonary status?
- rate, pattern, effort of respiration
- tracheal position
- expansion of thorax and use of accessory muscles
- characteristics of skin and soft tissues
What do you hear with normal auscultation?
- First you will hear the tracheobronchial tree
- where: heard best over trachea, right sternoclavicular joint, posterior right interscapular space
- Quality: higher, hollow pitch; equal on inspiration and expiration w/ short pause
- Vesicular
- Where: lung tissue
- Quality: lower pitched, softer, shorter expiration
You shouldn’t hear bronchial air sounds anywhere other than the bronchial tree. What does it mean if you do?
- It means that there is no ventilation into the alveoli
- Could be caused by:
- Consolidation- sounds like low pitched bronchial breathing (pulm edema, etc)
- Cavitary disease- sounds like high pitched bronchial breathing. (tb, malignant, etc)
What are the abnormal adventitious sounds?
- Wheeze (high pitched), Rhonchi (low pitched)
- musical, usually on expiration but may be on inspiration
- Stridor
- high pitched, usally inspiration
- Crackles/Rales
- tearing velcro open
What is the purpose of pulmonary function tests?
When are they indicated?
- Purpose:
- standardized
- objective
- Indication
- assist in diagnosis of a disease
- to evaluate a treatment
- to monitor disease progression
- Assess the risk- will they tolerate removal of part of lung, etc.
Who would be appropriate patients to do PFTs on?
- Patients with evidence of COPD
- smokers with a persistent cough
- wheezing or dyspnea on exertion
- morbid obesity
- thoracic surgery patients
- open upper abdominal procedures
- patients >70 years
- Routine PFTs are NOT recommended
What are tests that assess abnormalities in gas exchange?
Mechanical dysfunction?
- Abnormalities of gas exchange
- ABG
- pulse oximetry
- capnography
- Mechanical dysfunction of lungs and chest well
- spirometry
- **All are considered PFTs
What are the normal values for Volume and flow?
How are these determined?
- Spirometry
- Volume- normal 80-120% of predicted value
- Flow- normal is 80% of predicted value
- Predicted values based on:
- age
- height/weight
- gender
- ethnicity
Quick review of pulmonary disease:
Obstructive
Restrictive
- Obstructive
- airflow obstruction- chronic bronchitis or emphysema; progressive
- Asthma- chronic inflammatory disorder; reversible
- Restrictive
- proportional decreases in ALL lung volumes
What is Vital capacity?
- Most commonly measured; measured by simple spirometry
- Maximal inspiration followed by maximal exhalation to RV
- independent of rate of effort
- values should decrease as person goes from sitting to supine
- Normal is >/=80% of predicted value
What is Forced Vital Capacity (FVC)?
How do you interpret the results?
- Pt takes in maximum inspiration and forces exhalation
- Function of volume/time
- measures resistance to flow
- depends on pts effort and cooperation
- Interpretation:
- normal: 80-120%
- Mild: 70-79%
- Moderate: 50-69%
- Severe: <50%
What is the Forced expiratory volume in 1 second (FEV1)?
- Volume of air forcefully expired from full inspiration in the first second
- Normal is 75-80% of FVC
- Depends on effort and cooperation
- Interpretation:
- Normal: >75%
- Mild: 60-75%
- Moderate: 50-59%
- Severe: <49%
How do pulmonary function tests compare btw obstructive and restrictive disease?
(table)
What is the Forced expiratory flow 25-75% (FEF25-75%)?
How is it interpreted?
- Mean forced expiratory flow during the middle of the FVC
- May be independent of effort and shows status of the small airways
- Sensitive to early stages of obstructive disease
- More reliable than FEV1/FVC ratio
- Interpretation:
- Normal: >60%
- Mild: 40-60%
- Moderate: 20-40%
- Severe: <10%
What is Maximum voluntary ventilation (MVV)?
What happens to the MVV with obstructive disease?
Restrictive?
- the largest volume that can be breathed in one minute by voluntary effort
- test is actually performed over 10, 12, or 15 seconds
- Normal results may vary up to 3%
- MVV reduced is obstructive disease
- MVV normal is restrictive disease
- might be reduced with muscular disorders due to progressive weakness
- **not often used anymore, too much variability in results
What is the Functional residual capacity (FRC)?
What is its function?
- Volume of gas in the lungs after passive exhalation
- RV is the volume of gas in lungs after forced maximal expiration
- Function:
- It is a poing on the pressure-volume curve for resting ventilation
- Quantify the degree of pulmonary restriction
How is FRC measured?
- Measured indirectly
- Nitrogen wash-out (breath 100%FiO2
- Nitrogen analyzer attached to a spirometer
- Nitrogen measured w/each breath
- End point is when the alveolar nitrogen concentration falls below 7%, usually takes about 7-10 minutes
- measure total volume required for wash-out
Describe a flow volume loop
- Top part is exhalation, bottom is inhalation
- steep climb is the effort dependent exhalation
- flow is L/sec- y axis
- volume is L- x axis
Why is there a curve on the flow volume loop for obstructive disease?
because after you force the initial air out, the airways are starting to collaps, decreasing the rate of the rest of the air
???
What would you expect a flow volume look like for restrictive disease?
- same shape as normal, but lower volume
What does the blood flow through the lungs depend on?
- Blood flow in lungs largely gravity dependent
- alveolar- capillary beds are softer, less rigid
- surrounding tissues can cause resistance through the capillaries- can be squished
- Flood flow depends on relationship btw:
- pulmonary artery pressure (Ppa)
- Alveolar pressure (PA)
- Pulmonary venous pressure (Ppv)
What are the different zones of the lungs?
What is different between them?
- Zone 1: PA > Pa> Pv
- most independent on gravity
- Alveolar pressure is atmospheric
- Pa < PA does not occur under normal circumstances- seen in shock when pressure isnt high enough to perfuse
- ventilation, but little perfusion (dead space)
- Zone 2: Pa >PA > Pv
- Pa pressure increased d/t hydrostatic effect gravity)
- best matched ventilation and perfusion
- most alveoli are here
- Zone 3: Pa >Pv > PA
- Pv >PA
- perfusion greater than ventilation (shunt)
- greater change in pressure here during inspiration that at the top, more gas sucked into bases
When sitting up and awake,
Where is perfusion lowest?
where are the alveoli compressed?
What do you see when somebody has good compliance?
- Perfusion is lowest at the highest portion of the lung
- Perfusion increases in more dependent part of lung
- Alveoli are compressed in the lower parts d/t gravity
- With good compliance, large TV will reach the bases, which is important b/c the dependent lung has the greatest ventilation and perfusion (gas exchange)
What happens to blood flow when supine?
- uniform blood flow from apices to base
- Anterior : zone 1
- posterior: zone 3
What are the physiologic effects of PPV?
- Increased dead space
- increase in intrathoracic pressure causes decrease in venous return and CO
- ventilation with low perfusion causing an increase in V/Q mismatch
- Potential for alveolar over distension and rupture (barotrauma)
- risk for atelectasis- with inadequate TVs
How can you avoid the negative side effects of PPV?
- Maintain Peak airway pressures < 40 cm H2O
- Increase FiO2
- deliver an adequate TV
- maintain perfusion pressures to the lung
- fluids
- pressors
- comprssion socks
- trendelenberg- not ideal
- PEEP
- assess and reassess
How can we maximize pulmonary function for our patients?
- Goal to reduce intraop M&M
- smoking cessation
- can reduce carboxyHgb within 24 hrs
- mobilization of secretions/treat infections
- bronchospasm treatment
- improve motivation and stamina
- deep breathing, IS
- smoking cessation
Timeline of changes after cessation of smoking
- 12-24 hours: will reduce carboxyHgb to normal levels
- 2-3 weeks: mucociliary function returns; may have increased secretions
- 6 weeks: reduction in secretions
- 8 weeks: rate of post-op pulmonary complications decreases
How can you help mobilize secretions?
- hydration
- aerosol therapy
- mechanical therapy- percussion/vibration
- mucolytic agents- sometimes cause more problems than it is worth; not good if they dont have a good cough
- Abx for chronic bronchitis- should be dealt with way before surgyer
How can bronchospasm be treated?
- B2 agonists- have them take before surgery
- anticholinergic compounds
- ipratroprium- can help prolong effect of B2
- methylxanthines
- Corticosteroids
- minimal systemic absorption from the inhaled steroids
- wont need stress dose
Anesthetic management of Restrictive pulmonary disease?
- Titrate pre-op sedation carefully d/t reduced FRC
- Nitrous oxide +/-
- Regional is good unless it goes about T10 b/c they would lose accessory muscles that they probably depend on
- Inhalation agents have accelerated uptake d/t decreased FRC
- Must be efficient, will not tolerate long apneic time d/t small FRC
How should you plan to ventilate a pt with RLD?
- expect increased peak airway pressure
- decrease volume to 4-8 ml/kg
- increase rate 14-18
- PEEP
How does FRC decrease in normal health patients?
when supine
when under GA
how long to recover?
- 10-15% reduction in FRC in supine position
- addition 5-10% reduction with GA
- plateau after 10 minutes
- May take up to 3-7 days to recover FRC after upper abdominal procedure
- VC may have up to 40% reduction and take up to 14 days to return to normal after an upper abdominal procedure
Anesthetic management of Obsturctive lung disease?
- reduce airway reactivity
- bronchodilator
- IA good
- Opioids and lidocaine to prevent problems with manipulation
- steroids
- LMAs are good
- Otherwise avoid spontaneously ventilation under GA
- may start hyperventilating, may not be able to exhale adequately, causing intrinsic peep
- Regional anesthesia
- >T10 will lose accessory muscles that they might depend on
- Use of nitrous oxide +/-
- Larger TV
- keep PIP <40
- longer expiratory time
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