S2 Ch 2 Pulm 3-2

Front 1

455. Pathology of Adult Respiratory Distress Syndrome?

Back 1

a. ARDS is a diffuse INFLAMMATORY process (not necessarily infectious) involving both lungs-neutrophil activation (due to a variety of causes) in the systemic or pulmonary circulation is the primary mechanism.
b. ARDS is not primary disease, but rather a disorder that arises due to other conditions are causing widespread inflammatory process.
c. Is a clinical diagnosis

Front 2

456. Pathophysiology of Adult Respiratory Distress Syndrome?

Back 2

a. Massive intrapulmonary shunting of blood is a key pathophysiologic events in the ARDS
b. Severe hypoxemia with no significant improvement 100% oxygen!!!!
c. Shunting secondary to widespread atelectasis, collapse of alveoli, and surfactant release.
d. Decreased pulmonary compliance-leads to increased work of breathing
e. Increased dead space-2° to obstruction and destruction of pulmonary capillary bed
f. Low vital capacity
g. Low FRC.

Front 3

457. In ARDS what is interstitial edema and alveolar collapse due to?

Back 3

a. An ↑ In lung fluid, which leads to stiff lungs, increasing alveolar – arterial oxygen difference (A-a gradient), and ineffective gas exchange.
b. Note: the EFFECTS of the increase in pulmonary fluid are identical to the scene cardiogenic pulmonary edema, but the CAUSE is different:
i. An increase in alveolar capillary permeability causes ARDS, whereas congestive hydrostatic forces cause cardiogenic pulmonary edema

Front 4

458. Who has the highest risk of developing ARDS?

Back 4

a. Patients with sepsis or septic shock.
b. Sepsis is the most common risk factor for ARDS.

Front 5

459. Causes of ARDS?

Back 5

a. Sepsis is most common risk factor-can be secondary to a variety of infections (e.g., pneumonia, urosepsis, wound infections)
b. Aspiration of gastric contents
c. Severe trauma, fractures (e.g., femur, pelvis), acute pancreatitis, multiple or massive transfusions, near-drowning.
d. Drug overdose, toxic inhalations
e. Intracranial HTN
f. Cardiopulmonary bypass

Front 6

460. Clinical features of ARDS?

Back 6

a. Dyspnea, tachypnea, and tachycardia due to increased work of breathing.
b. Progressive hypoxemia-not responsive to supplemental oxygen (ratio of PaO2 to FIO2 <200).
c. Patients are difficult to ventilate because of high peak airway pressures due to stiff, noncompliant lungs.

Front 7

461. 4 diagnostic modalities for ARDS?

Back 7

1. CXR
2. ABG
3. Pulmonary artery catheter
4. Bronchoscopy with bronchoalveolar lavage

Front 8

462. What does the CXR demonstrate with ARDS?

Back 8

a. Bilateral pulmonary infiltrates!!!!
b. There is a variable correlation between findings on CXR and severity of hypoxemia or clinical response
c. Diuresis improves and volume overload worsens infiltrates
d. CXR improvement follows clinical improvement after 1 to 2 weeks or more.

Front 9

463. What does the ABG reveal with ARDS?

Back 9

a. Hypoxemia (PaO2 <60)
b. Initially, respiratory alkalosis (PaCO2 <40) is present
c. Which gives way to respiratory acidosis as the work of breathing increases and PaCO2 increases.
d. If the patient is septic, metabolic acidosis may be present, with or without respiratory compensation.

Front 10

464. Utility of pulmonary artery catheter for ARDS?

Back 10

a. Enables a determination of pulmonary capillary wedge pressure (PCWP).
b. PCWP reflects left heart filling pressures and is an indirect marker of intravascular volume status.
c. PCWP is the most useful parameter in differentiating ARDS from cardiogenic pulmonary edema!!!!!!

Front 11

465. How does PCWP differentiate ARDS from cardiogenic pulmonary edema?!?

Back 11

a. If PCWP is low (<18 mm Hg), ARDS is more likely
b. Whereas, if PCWP is high (>18 mm Hg), cardiogenic pulmonary edema is more likely.

Front 12

466. Utility of bronchoscopy with bronchoalveolar lavage for ARDS?

Back 12

a. This may be considered if patient is acutely ill infection is suspected
b. Fluid collected can be cultured and analyzed for cell-differential, cytology, Gram stain, and silver stain.

Front 13

467. Treatment of ARDS?

Back 13

a. Oxygenation-try to keep O2 saturation > 90%
b. Mechanical ventilation with PEEP is usually required. It served to increase lung volume by opening collapsed alveoli and decreasing shunting.
c. Fluid management
d. Treat the underlying cause (ie infection)
e. Do not forget to address the patient's nutritional needs-tube feedings are preferred over parenteral nutrition.

Front 14

468. Fluid management in the treatment of ARDS?

Back 14

a. Volume overload should be avoided.
b. A low – normal intravascular volume is preferred
c. The goal should be a PCWP of 12 to 15 mm Hg. Vasopressors may be needed to maintain BP.
d. On the other hand, patients with sepsis have high fluid requirements, so determining the appropriate fluid management may be difficult.

Front 15

469. Remember the following when examining a patient ARDS?

Back 15

a. Physical findings are usually nonspecific
b. Bc the patient is usually integrated and on a ventilator, decreased unilateral breath sounds may be due to the endotracheal tube being in the right main bronchus or possibly a pneumothorax.
c. Look for potential sources of sepsis and check for any signs of infection: acute abdomen, IV lines, wounds, decubiti.
d. Keep in mind cardiogenic pulmonary edema has to be distinguished from ARDS- look for signs of volume overload, CHF, JVD, edema, and hepatomegaly.

Front 16

470. Note: ARDS can progress rapidly over several hours. Initially, the dyspnea may be exertional but it can rapidly advance in severity.

Back 16

470. Note: ARDS can progress rapidly over several hours. Initially, the dyspnea may be exertional but it can rapidly advance in severity.

Front 17

471. Classic clinical criteria for diagnosing ARDS?

Back 17

a. Hypoxemia is refractory oxygen therapy: ratio of PaO2/FIO2 ≤200.
b. Bilateral diffuse pulmonary infiltrates on CXR
c. No evidence of CHF: PCWP ≤18.

Front 18

472. Complications of ARDS?

Back 18

1. Permanent lung injury-resulting in lung scarring or honeycombing.
2. Complications associated with mechanical ventilation
3. Line-associated infections
4. Renal failure
5. Ileus, stress ulcers
6. Multiple organ failure
7. Critical illness myopathy

Front 19

473. Complications associated with mechanical ventilation in ARDS?

Back 19

a. Barotrauma 2° to high-pressure mechanical ventilation, possibly causing a pneumothorax or pneumomediastinum
b. Nosocomial pneumonia

Front 20

474. What may renal failure 2° to in ARDS?

Back 20

a. Nephrotoxic medications
b. Sepsis with hypotension
c. Underlying disease

Front 21

475. What are the 2 major goals of treating respiratory failure?

Back 21

1. Maintain alveolar ventilation
2. Correct hypoxemia

Front 22

476. The decision to initiate mechanical ventilation should be a clinical one, pts with what conditions require mechanical ventilation?

Back 22

a. Significant respiratory distress (e.g., high RR) or respiratory arrest
b. Impaired or reduced level of consciousness inability to protect airway (look for absent gag or cough reflex)
c. Metabolic acidosis (if patient is unable to compensate with adequate hyperventilation)
d. Respiratory muscle fatigue
e. Significant hypoxemia (PaO2 < 70) or hypercapnia (PaCo2 >50); respiratory acidosis (pH <7.2) with hypercapnia

Front 23

477. What is used to assess the response to mechanical ventilation?

Back 23

a. ABGs are used to assess response to initiation of mechanical ventilation.

Front 24

478. Acceptable ranges of gas values on ABG after initiating mechanical ventilation (Pao2, PaCo2, pH)?

Back 24

a. PaO2 of 50-60
b. With
c. PaCo2 of 40-50
d. And
e. pH between 7.35-7.50