Respiratory

Question 1

Common causes of transudative pleural effusion.

Answer 1

CHF, cirrhosis with ascites, nephrotic syndrome

Fluid is sterile, pushed out of vessels into pleural space due to hydrostatic pressure.

Question 2

Troubleshooting the PLEUR VAC

Answer 2

If there’s and increase of bubbling amount and frequency in the water chamber, there’s air in the pleural space. Look for big changes.

Troubleshhooting: look for kinks, obstruction, tube migration and leaks

Question 3

What is the MRC dyspnea scale?

Answer 3

Grades severity of dyspnea in respiratory disease

For bonus points:
0) breathless with strenuous exercise
1) SOB when hurrying on level ground or walking uphill
2) walk slower than others in own age group on level ground, or stop for breath when walking at own pace
3) stop for breath after 100 meters or a few minutes on level ground
4) too breathless to leave the house or breathless when dressing/undressing

Question 4

Hemoptysis treatment considerations

Answer 4

• If bleeding source is known, position bleeding side down.
• Manipulate intubation to ventilate “good” lung, i.e. right mainstem. If this is done, reduce Vt to avoid overpressurizing the one good lung.
• Anticoagulant reversal
• PPV with PEEP may assist.

Question 5

What are the commonly prescribed antibiotics for pneumonia?

Answer 5

Azithromyacin and ceftriaxone

Question 6

Significance and determination of empyema

Answer 6

Watch for empyema as it’s a common sepsis source!

Serum will show pH <7.3, increased lactate, proteins and/or LDH compared to blood sample.

Suspect empyema if pt is febrile, hemodynamically unstable, or has productive cough.

Empyema tx is drainage, antibiotics and possibly thrombolytics into pleural space to break off loculated empyemas. Thoracic surgery in severe cases.

Question 7

Hemoptysis causes and concerns

Answer 7

Bleeding is either localized or diffuse due to alveolar damage.

Most often caused by CA, TB, PE or pneumonia.

Over 150cc of blood in 24 hours is very concerning as there is always more blood below than what is brought up. Biggest concern is asphyxiation.

RARELY causes hypovolemia

Question 8

Common causes of exudative pleural effusion

Answer 8

• Infection (TB/pneumonia/abcess)
• Malignancy
• Pulmonary embolism
• Pancreatitis
• Post cardiac injury syndrome

Inflammatory process causes effusion

Question 9

What are the two antifibrotics prescribed for interstitial lung disease?

Answer 9

Perfedinone & Ninetedanib

We care, because if a patient has these prescribed they are likely ILD patients.

Question 10

Which prescribed medication for pulmonary hypertension should NEVER be stopped?

It’s delivered by pump…

Answer 10

Epoprostenol: a pulmonary vasodilator that has a very short half life. Discontinuing may cause a sudden increase in RV afterload leading to acute RV failure.

Question 11

Mech Vent strategies in pulmonary hypertension

Answer 11

• Avoid hypoxemia, hypercarbia and acidosis as they will worsen PVR (further vasoconstriction) and therefore RV function.
• Avoid high inspiratory pressure and auto PEEP to keep intrathoracic pressure as low as possible.
• Ketamine is a preferred induction agent due to its bronchodilatory properties. Use lower end of dosing to prevent any adverse effects.
• Give pressors prior to intubation. Norepi provides a balance of inotropic support without increasing heart rate or PVR. Vasopressin can also be considered as it may actually reduce PVR while increasing SVR.
• Be prepared for PEA arrest shortly after intubation.

Most pressing is the demand on the RV, and the conflicting increase in RV afterload that comes with PPV. Efforts should be made to reduce RV afterload and PVR prior to intubating.

Question 12

5 mechanisms of hypoxia
and possible treatments

Answer 12

1) Decreased atmospheric pressure
increase FiO2
2) V/Q mismatch
position for perfusion, adress hemodynamics, O2 and ventilation
3) R-L shunt (extreme V/Q, ASD or VSD), suspect in failure of PaO2 to rise despite increased FiO2.
4) Increased O2 extraction
reduce demand
5) Diffusion impairment
Increase surface area, reduce membrane thickness

Hypoventilation may be considered as a 6th mechanism, though this is more associated with hypercapnia.

Question 13

Treatments for COPD exacerbations

Answer 13

Similar to asthma, with exclusion of epi* and higher suspicion of infectious cause so earlier antibiotic administration.

See pulmonary hypertension considerations for mechanical ventilation. NIPPV may be effective.

*COPD is an alveolar disease, and epi works on bronchioles, so considering risk/benefit profile in these patients - who often have comorbidities, epi is relatively contraindicated here.

Question 14

What rating scales are used for pneumonia patients?

Answer 14

The PSI (pneumonia severity scale) helps determine the need for ICU care, and CURB-65 predicts mortality.

Question 15

COPD ABG considerations

Answer 15

These patients are usually hypercapnic at baseline. A derangement in pH indicates an acute-on-chronic exacerbation, as new metabolic compensation takes 3-5 days to actualize.

Question 16

Describe FEV1/FVC ratio and its significance

Answer 16

Compares fraction of exhaled air in 1st second to total amount exhaled forcefully after a deep breath. Should be <0.7. If the FEV1 is <50%, this indicates severe obstructive disease.

Question 17

What’s the cause of obstructive shock leading to cardiac arrest in a tension pneumothorax?

Answer 17

Compression of the cavo-atrial junction.

Question 18

Patho, signs and treatment for re-expansion pulmonary edema

Answer 18

Occurs when rapid re-expansion causes negative pressure in the alveoli, dragging fluid into them.

Patients develop SOB/CP, crackles, increased rate and amount of fluid in chest tube.

• clamp tube (release can then be titrated to pt. symptoms)
• sit upright to drain edema to bases
• O2 & supportive care

Question 19

Common causes of COPD exacerbation

Answer 19

• Infection (50%)
• CHF/MI
• Allergen exposure
• PE (20-25%!)
• unknown

Question 20

Risk factors and causes of interstitial lung disease (ILD)

Answer 20

Risks are age >50, male, smoking hx, reflux and genetics.

Caused by:
* exposures birds, mold, farms
* meds amiodarone, metotrexate
* connective tissue disease scleroderma
* granulomas sarcoid, TB, fungal

May also be idiopathic

Question 21

What is the significance of clubbing?

Answer 21

Usually occurs in chronic conditions. Most common causes are malignancy, TB and liver disease.

Question 22

Structural clues for differing etiologies in chest xrays

Think heart, diaphragm, trachea

Answer 22

Is it collapse, cells or fluid/pus?

Atalectasis will “suck in” structures
A mass will push them away
Consolidation will keep them the same

Question 23

What is the A-a gradient

Answer 23

Difference betwen alveolar (A) and arterial (a) oxygen content. Usually between 5-15mmHg

Question 24

Cardiac consequences of pulmonary hypertension, AKA: the vicious RV overload cycle

Answer 24

1. As PH progresses, the RV becomes overloaded, whic eventually decreasesLV preload through septum shift and reduced LV contractility, as well as “tugging” on the LV.
2. This causes reduced CO, leading to,
3. Systemic hypotension, and,
4. Reduced RV tissue perfusion and RV free wall ischemia, and then,
5. Reduced RV contractility - which brings us back to No. 1 again!

Question 25

What are the benefits of **prone positioning**

Answer 25

Though proning decreases chest wall compliance, it should assist in recruiting more lung. * More even distribution of gas/tissue ratios, and more homogenous distribution of lung stress. * O2/CO2 exchange should improve as dorsal surface is larrger and priority circulation moves to the dorsal region. * RV function may also improve with reduction in pulmonary hypertension * Less need for high PEEP can further improve hemodynamics When P:F ration >150, consider proning!

Question 26

Describe the **Berlin Criteria**

Answer 26

Used to identify pt's with severe lung injury/ARDS * Timing: onset within 7 days * CXR shows bi-lateral opacities not explained by effusions, lobar collapse or nodules * Pulmonary edema cannot be caused by cardiac failure * Low PaO2 with PEEP 5+: calculating a P:F ratio will determine a mild (201-300), moderate (101-200) or severe (100 and less) category of severity.

Question 27

What is **alveolar surface tension**?

Answer 27

This describes the propensity of alveoli to collapse (draw together), and is reduced by surfactant. Conditions disturbing surfactant production (ARDS, COPD) will increase collapsing pressure.

Question 28

What are the effects of **ARDS**?

Answer 28

Release of inflammatory mediators leads to: . * Increased permeability and engorgement of capillary membrane: alveolar flooding and damage to Type 1 & Type 2 (where surfactant is produced) epithelial cells in the alveoli, and subsequent alveolar collapse - **shunt** * Interstitial and alveolar edema and hemorrhage, microemboli leading to pulmonary hyertension, RV afterload and reduced CO - alveolar **dead space**. * A thick hyaline membrane developls, leading to intraaveolar fibrosis, smaller airway diameter: increased airway resistance, reduced compliance and increased WOB

Question 29

What are the most common causes of **ARDS**?

Answer 29

* Sepsis * Aspiration * Pneumonia * Trauma * Pancreatitis * Endocarditis

Question 30

Describe **obstructive** lung disease

Answer 30

Conditions which impede normal air flow. Often these patients are able to inhale, but have difficulty exhaling (reduced FEV1): * emphysema * asthma * cystic fibrosis * bronchiectasis High risk of **breath stacking**. *Because lungs become hyperinflated, and loose elastance, there us usually an increase in Reserve Volume (RV), FRC and total lung capacity*

Question 31

Describe **restrictive** lung disease

Answer 31

Conditions that impair or limit chest wall movement: * interstitial lung fibrosis * kyphoscoliosis * severe chest wall pain * atelectasis High risk of **overpressurizing** *Smaller Vt's and reduction in all lung capacities result in an increased ventilatory rate to maintain minute ventilation*