Respiratory Physiology/Pathology - Respiratory Failure

Question 1

Obstructive vs Restrictive vs Lung Circulation Diseases

Answer 1

Obstructive: Affect the airway → airflow limitation
Restrictive: Lung tissue diseases, affect structure of lung tissue (e.g. alveoli). Pleura and mediastinum.
Lung circulation diseases: affect blood vessels in lungs (e.g. pulmonary hypertension).

Question 2

Hypoxemia - Classification

Answer 2

Is referred to low oxygen levels in the arterial blood.
Normal: PaO2: 80-100 mmHg, SaO2: >95%
Mild hypoxemia: PaO2: 60-79 mmHg, SaO2: 90-94%
Moderate hypoxemia: PaO2: 40-59, SaO2: 75-89%
Severe hypoxemia: PaO2: <40 mmHg, SaO2: <75%

Question 3

Hypercapnia

Answer 3

Abnormal elevated carbon dioxide levels in the arterial
blood.
In conjunction with hypoventilation: PaCO2: >45 mmHg
Increased CO2 → Decreased pH

Question 4

Hypocapnia

Answer 4

Abnormally decreased carbon dioxide levels in the arterial blood.
In conjunction with hyperventilation: PaCO2: <35 mmHg
Decreased CO2 → Increased pH

Question 5

Hypoxia

Answer 5

Condition where the body or a region is deprived of adequate oxygen supply (high altitudes, preterm birth.

Question 6

Anoxia

Answer 6

Complete deprivation of oxygen

Question 7

Oxygen Saturation

Answer 7

Measure of amount of hemoglobin carrying oxygen relative to the amount of hemoglobin not carrying oxygen.

Question 8

Respiratory Rate (normal ranges - new born, infant, adult)

Answer 8

• New born: 40- 45 breaths/min
• Infant: 25-30 breaths/min
• Adult: 10-14 breaths/min

Question 9

Hyperventilation

Answer 9

↑ respiratory rate
↑ tidal volume
- ↑ minute ventilation
- pCO2 too low (Hypocapnia)
  - ↑ pH Value
    - (respiratory) alkalosis
    - dizziness, lightheaded, muscle spasm, confusion, palpitations, dyspnea
Compensation: renal excretion HCO3 → pH-value decreases again

Question 10

Hypoventilation

Answer 10

⇵ Respiratory rate
↓ Tidal volume
↓ elimination of CO2 during expiration
↓ loading of O2 during inspiration
- Hypercapnia with acidosis
- Hypoxemia
- ↓ pH
-Headache, anxiety, blurred vision, restlessness, confusion.
Compensation: renal absorption HCO3 → pH ↑
Normally associated with tachypnea and respiratory failure II.

Question 11

Tachypnoea

Answer 11

Increased RR > 20 breaths/min

Question 12

Bradypnoea

Answer 12

Decreased RR <10 breaths/min

Question 13

Apnea

Answer 13

Cessation of breathing

Question 14

Dyspnea

Answer 14

It is the conscious perception of breathing effort. Occur when there is a discrepancy between the neural drive to breath and the level of ventilation achieved.- BREATHLESSNESS!!!!

Question 15

Orthopnea

Answer 15

shortness of breath when lying flat

Question 16

Eupnoea

Answer 16

normal breathing pattern

Question 17

Arterial Blood Gases (pH, pO2, pCO2)

Answer 17

pH: 7.35 - 7.45
pO2: 80-100 mmHg
pCO2: 35-45 mmHg

Question 18

Venous Blood Gases (pH, pO2, pCO2)

Answer 18

pH: 7.33 - 7.38
pO2: 35-40 mmHg
pCO2: 41-51 mmHg

Question 19

Acidosis vs Alkalosis - Compensation

Answer 19

Acidosis (pH<7.35) vs alkalosis (pH>7.45)
 lungs (ventilation):
↑ rate ↓ PCO ↑ pH
↓ rate ↑ PCO ↓ pH
kidneys (HCO3):
Absorb HCO3 ↑ pH
Excrete HCO3 ↓ pH

Question 20

Respiratory Failure - Definition and Cause

Answer 20

Disorder of pulmonary gas exchange with pathologically altered blood gas values, ↑ respiratory rate and ↑ work of breathing
General causes:
• ↓ Airflow (eg. obstruction)
• ↓ Breathing ability (eg. chest wall changes)
• ↓ Blood supply to lungs
• Gas exchange problems

Question 21

Respiratory Failure Type I

Answer 21

pO2 ↓(moderate hypoxemia; <60 mmHg), pCO2 normal (normocapnia; <50mm Hg)
Gas exchange problems

Question 22

Respiratory Failure Type I - Cause

Answer 22

Mostly due to lung damage
Low ambient O2 (e.g. at high altitude)
Ventilation-perfusion mismatch:
• Ventilation issue: e.g. edema/pneumonia
• Perfusion issue: e.g. embolism
Diffusion problem (fluid filling / collapse alveoli)
Right to left cardiac shunt (low-oxygenated systemic blood bypasses lungs)

Question 23

Respiratory Failure Type I - Symptoms

Answer 23

Tachypnoea, Dyspnea
Cyanosis (bluish blood - extremities, nose, mouth)
Restlessness
Confusion
Hyperhidrosis
Heart rate ↑
Blood pressure ↑

Question 24

Respiratory Failure Type II

Answer 24

Ventilatory failure/Pump failure
pO2 ↓ (Hypoxemia), pCO2 ↑ (Hypercapnia)
pO2 < 60mmHg
PCO2 > 50mmHg (35-45 normal)
pH decreased
Can be a consequence of respiratory failure type I.

Question 25

Respiratory Failure Type II - Cause

Answer 25

Ventilatory muscles can’t operate at maximum capacity all the time: → They fail → ventilatory failure.
Neuromuscular disease → Respiratory muscles don’t work → ventilatory failure.
- Reduced breathing effort
- Increased airway resistance (COPD, asthma)
- Stroke/medication problems

Question 26

Respiratory Failure Type II - Symptoms

Answer 26

• Impaired consciousness
• Blood pressure ↓
- Heart rate ↓ until asystole
- Convulsions because of lack of O in the brain

Question 27

Respiratory Failure - Treatment

Answer 27

Acute → medical emergency → ICU (intensive care unit)
Chronic → often at home
Main goals:
1) Get O2 to organs & remove CO2 from body
2) Treat underlying course
Oxygen Therapy and Ventilator Support (does not treat underlying cause)
Physiotherapy → Improve respiratory function

Question 28

Respiratory Failure - Level of Oxygenation

Answer 28

Arterial oxygen pressure (PaO2) (80-100 normal) Inspired oxygen (FiO2) (normal 0.21, 21% in room air)
PaO2/FiO2= 80/0.21= 380
PaO2/FiO2= 100/0.21= 475
If patient has oxygen therapy:
PaO2/FiO2= 100/0.35= 285
Mild: 200