Respiratory Disorders

Question 1

What is Respiratory Failure?

Answer 1

“respiratory dysfunction resulting in abnormalities of oxygenation or ventilation (CO 2 elimination) severe enough to threaten the function of vital organs.” (Current 2024)

Question 2

Type I vs Type II respiratory failure

Answer 2

● Type I Respiratory Failure is the inability to provide sufficient oxygen
à hypoxia
● Type II Respiratory Failure is the inability to remove carbon dioxide
à hypercapnia

Question 3

Causes of Pulmonary edema

Answer 3

● Increased hydrostatic pressure
● LV dysfunction (eg, myocardial
ischemia, HF)
● Mitral regurgitation
● Left atrial outflow obstruction (eg,
mitral stenosis)
● Volume overload states
● Increased pulmonary capillary
permeability
● Acute respiratory distress syndrome

Question 4

Parenchymal lung disorders

Answer 4

● Pneumonia
● Interstitial lung diseases
● Diffuse alveolar hemorrhage
syndromes
● Aspiration
● Lung contusion

Question 5

Pulmonary vascular disorders

Answer 5

● Thromboembolism
● Air embolism
● Amniotic fluid embolism

Question 6

Chest wall, diaphragm, and pleural
disorders

Answer 6

● Rib fracture
● Flail chest
● Pneumothorax
● Pleural effusion
● Massive ascites
● Abdominal distention and abdominal
compartment syndrome

Question 7

Acute Resp Distress Syndrome

Answer 7

It is an acute hypoxemic respiratory failure following a systemic or pulmonary insult that results in fluid accumulation in the lungs without evidence of heart failure (cardiogenic pulmonary edema)

Question 8

“Berlin” definition of ARDS:

Answer 8

1) acute onset,
2) bilateral pulmonary infiltrates on CXR/CT, and
3) poor oxygenation (PaO2/FiO2 <300 mmHGg)

Question 9

Several disorders/conditions associated with ARDS, 75% are
found in one of three settings:

Answer 9

○ Sepsis (most common)
○ Severe multiple trauma
○ Aspiration of gastric contents

Question 10

Pathophysiology of ARDS

Answer 10

○ Inflammatory response to the insult (whether primary or secondary)
○ large amounts of pro-inflammatory cytokines are released throughout the lungs
○ Widespread cytokine release triggers immense immune response, damaging the
pulmonary capillary epithelium
○ Damage to the capillary wall –>
○ marked increased capillary permeability, and
○ decreased surfactant production/activity

Question 11

In ARDS, Damage to the capillary wall à
○ marked increased capillary permeability, and
○ decreased surfactant production/activity

Answer 11

1. Interstitial edema
2. Alveolar edema
3. Alveolar collapse/noncompliance
4. Profound hypoxemia

Question 12

ARDS: Clinical Presentation

Answer 12

● Rapid onset of profound dyspnea.
■ Occurs 6-72 hours after precipitating event
■ Within 12-24 hrs à may see rapid deteriorationà intubate
○ Other signs and symptoms:
■ Tachypnea
■ Frothy pink/red sputum
■ Diffuse crackles
■ Retractions
■ Cyanosis with increasingly severe
hypoxemia (<90%) that is refractory to
oxygen administration

Question 13

ARDS - Diagnosis

Answer 13

● Once symptoms set in, CXR becomes remarkable:
■ Diffuse or patchy bilateral infiltrates
● Infiltrates rapidly become confluent
● Characteristically spare the costophrenic angle
■ Pleural effusions are small or non-existent
■ Air bronchograms are seen in 80% of cases

Question 14

CXR findings in ARDS

Answer 14

bilat pulmonary infiltrates
○ Generally normal cardiac silhouette

Question 15

ABG findings in ARDS

Answer 15

○ PaO2 ↓ (<60 mmHg - always until ARDS resolves)
○ PaCO2 ↑ or normal

Question 16

BNP findings in ARDS

Answer 16

BNP (helps differentiate ARDS from cardiopulmonary edema)
○ Obtain if enlarged pulmonary cardiac silhouette
■ High - points to cardiopulmonary edema
■ Low/normal - points to ARDS

Question 17

ABGs importance in ARDS = PaO2 & FiO2

Answer 17

1. PaO2 = Measures partial pressure of oxygen in the blood
   a. Represents how well we are getting oxygen across the
   alveolus into the capillary
2. FiO2 = fraction of oxygen that the patient is breathing
3. PaCo2 = not an important measurement in ARDS
4. With PEEP you adjust FiO2 in order to maintain the patient at >90%
   saturation
   Ratios between PaO2 and FiO2 give you a better idea of the severity of ARDS and contribute to the diagnosis of
   ARDS- however this is not the scope of this lecture and more advanced ICU respiratory medicine

Question 18

ARDS - Treatment Management

Answer 18

1. Identification and aggressive treatment of the precipitating condition
2. Focus on meticulous and aggressive supportive care.
   ○ Tracheal intubation
   ○ Positive pressure mechanical ventilation (PEEP)
   ■ Target of SaO2 > 88%

Question 19

Indications for intubation and ventilation include:

Answer 19

○ Hypoxemia despite delivery of supplemental oxygen
○ Upper airway obstruction (epiglottitis, for example)
○ Impaired airway protection (coma)
○ Inability to clear secretions
○ Severe respiratory acidosis
○ Progressive respiratory distress (ARDS, etc)
○ Apnea

Question 20

Complications of Mechanical Ventilation include:

Answer 20

○ NUMEROUS!
○ Atelectasis (partial or complete collapse of one lung)
○ Hyperinflation (usually of one side)
○ Pneumothorax
○ Ventilator-Acquired Lung Injury

Question 21

ARDS Prognosis:

Answer 21

○ Mortality rate associated with ARDS is 30-50%.
■ If the ARDS was secondary to sepsis (which is true of about one third of ARDS cases), mortality rate can reach 90%
■ Median survival is about 2 weeks
from onset of ARDS

Question 22

Infant Resp Distress Syndrome

Answer 22

● IRDS was previously known as Hyaline Membrane Disease.
○ It is the most common cause of respiratory distress in the preterm infant.
● It is caused by prematurity of
the lungs and deficiency in
pulmonary surfactant

Question 23

IRDS Pathophysiology

Answer 23

○ Without surfactant, alveoli collapse
and gas exchange is hindered.
○ Pulmonary edema and atelectasis can
occur, with hyaline membrane
formation worsening gas exchange

Question 24

IRDS Clinical Presentation

Answer 24

○ Typical signs of respiratory distress
in the newborn…
■ Dyspnea, retractions, hypoxia, etc

Question 25

IRDS - Diagnosis

Answer 25

● Chest X-ray:
■ Diffuse sign of interstitial and alveolar congestion in the newborn baby.
■ Air bronchograms.
■ Interstitial reticular pattern (linear-ground glass appearance)
● ABG will usually reveal:
■ Hypoxemia
■ Hypercapnia
■ Respiratory acidosis without compensation

Question 26

Lecithin-Sphingomyelin Ratio (aka L-S or L/S Ratio)

Answer 26

1. Measures two substances:
   a. Lecithin (↑↑↑ as pregnancy progresses)
   b. Sphingomyelin (stays constant throughout all pregnancy)
2. These substances are found in the amniotic fluid during pregnancy
3. They are surfactants made by the lungs.
4. Without surfactants the alveoli collapse (no O2 in the blood)

Question 27

What are some complications from IRDS

Answer 27

● Alveolar collapse (as already mentioned)
● Patent ductus arteriosus
● If you give too much oxygen supplementation
○ Retinopathy of prematurity
■ Abnormal vessel growth in the retina - can cause detachment
○ Bronchopulmonary dysplasia
■ Chronic lung disease from ventilation

Question 28

IRDS - Treatment and Management

Answer 28

● Intubation with mechanical ventilation or CPAP with nasal bubble is required.
● Aerosolized exogenous surfactant

Question 29

IRDS - Prevention

Answer 29

● If an expecting mother is showing signs of premature labor, glucocorticoids can be administered to help stimulate maturation of the baby’s lungs.
■ Prescribed if labor prior to 34 weeks gestation
● With current knowledge and treatment, mortality rate for babies born at 27 weeks gestation or later is at 10%