Week 1 Respiratory Failure

Question 1

What is Critical Care?

Answer 1

A HIGHLY specialised service administered in ICU to patients with life-threatening injuries or illnesses.

Question 2

What is Hypoxemia

Answer 2

• Low oxygen levels in the blood

Question 3

What is hypoxia

Answer 3

• Low oxygen levels in the tissues

Question 4

Type 1 Respiratory Failure: Hypoxemic

Answer 4

Failure in Oxygenation (PaO2 <60mmHg) often occurs ACUTELY
- Failure of the “LUNG” or the gas exchange portion.
- Can be caused by a mismatch in V/Q, diffusion impairment or alveolar hypoventilation.
- Conditions like Pneumonia or Pulmonary Oedema

Question 5

Type 2 Respiratory Failure: Hypercapnic

Answer 5

Failure in CO2 elimination (PaCO2 >50mmhg), often occurs SLOWER and is associated with CHRONIC LUNG DISEASES
- Failure of the ventilatory/respiratory “PUMP”
- Results from problems with CNS, neurological pathways, respiratory muscles, lung elasticity, or chest wall.
- Commonly seen in COPD or Neuromuscular diseases

Question 6

Coexistence of Respiratory Failure

Answer 6

Both Type 1 and Type 2 can occur simultaneously or lead to each other

Question 7

Type 3 Respiratory Failure: Periooperative

Answer 7

Caused by atelectasis after surgery

Question 8

Type 4 Respiratory Failure: Shock

Answer 8

Caused by hypoperfusion in critical illness

Question 9

What are the effects of Hypoxemia

Answer 9

• Cellular Damage - due to acidosis and changes in potassium and calcium concentrations
• Systemic Response - body responds by hyperventilating, increasing cardiac output, vasodilation of blood vessels and increased hemoglobin production in chronic cases
• Symptoms: Confusion, impaired judgement, fatigue, drowsiness, delayed reaction, motor incoordination, and reduced muscle strength (Common symptoms)

Question 10

How does hypoxia affect cells

Answer 10

• Hypoxia causes cellular damage due to acidosis and changes in potassium and calcium concentrations
• Take note: different organs have different susceptibility (Cerebral cortex, heart, kidney, and skeletal muscles are more susceptible)

Question 11

What are the consequences of hypoxia?

Answer 11

• Oxygen dependency
• Switches from Aerobic to Anaerobic (less efficient)
• Organ Vulnerability (Brain, Kidney, Liver suffers)
• Muscle Adaptation (skeletal muscles can function longer on anerobic metabolism)

Question 12

Organ susceptibility to Hypoxia: The Cerebral Cortex

Answer 12

Most vulnerable, Damage occurs in 1-3 minutes of Hypoxia

Question 13

Organ susceptibility to Hypoxia: Heart

Answer 13

Susceptible after approximately 5 minutes of hypoxia

Question 14

Organ susceptibility to Hypoxia: Kidney

Answer 14

Can withstand Hypoxia for up to 10 minutes before damages occur

Question 15

Organ susceptibility to Hypoxia: Skeletal Muscle

Answer 15

Can survive anaerobic state

Question 16

Normal Level of PaO2

Answer 16

80-100mmHg

Question 17

When does Cellular change begin?

Answer 17

3-10mmHg drop in PaO2

Question 18

Loss of consciousness occur when PaO2 drops to?

Answer 18

<27mmHG

Question 19

What are the Compensatory Mechanisms in Respiratory Failure

Answer 19

• Lungs: Hyperventilation and selective VASOCONSTRICTION
• Cardiovascular System: Increase CO and Regional blood flow
• Sympathetic Nervous System: vasodilation to increase blood flow
• Hematological response: increase production of hemoglobin over time
• Brain - Cerebral Vasodilation

Question 20

What are the consequences of hypercapnia?

Answer 20

• Neurological effects: Primarily affects CONSCIOUSNESS, may lead to convulsion and coma when PaCO2 >90mmhg
• Cardiovascular Impact: can reduce heart contractility, cause arrhythmias, and lead to variable blood pressure responses (resulting in Hypertension)
• Muscular changes: May cause muscle hyperexcitability and spontaneous contractions

Question 21

What is acute respiratory Failure?

Answer 21

Sudden onset, often due to trauma, acute asthma attacks, pulmonary oedema, or upper airway obstruction. Requires immediate intervention to prevent rapid deterioration

Question 22

What is Chronic Respiratory Failure?

Answer 22

Develops over time, commonly seen in COPD patients, chest wall deformities, obesity, and neuromuscular diseases. (Patients may adapt to altered blood gas levels over time)

Question 23

What is acute-on-chronic Respiratory Failure?

Answer 23

• an acute exacerbation or deterioration in a patient with chronic respiratory failure. (Common in patients with COPD who experience acute deterioation.

Example: COPD patient with new infections or onsets

• Can be identified through arterial blood gas analysis, showing acute changes on top of chronic adaptations. (Patients may develop hypoxic drive for breathing)
• Triggers: new respiratory infections, heart failure, pulmonary embolism, medication non compliance

Question 24

How do we assess Respiratory Failure?

Answer 24

• We do a clinical assessment , we look for signs of respiratory distress such as cyanosis, changes in breathing pattern, altered posture, speech difficulties, restlessness and anxiety
• We look at their ABGs as it provides accurate measurements of PaO2 and PaCO2
• We can use a PULSE OXIMETRY, may be useful but has limitations

Question 25

Signs of Respiratory Distress on Adults

Answer 25

- Cyanosis - Altered breathing pattern - Abnormal posture - Speech difficulties - Restlessness or anxiety - Stridor - narrowing of trachea (high pitch wheeze) - Tachycardia

Question 26

Signs of Respiratory Distress on Children

Answer 26

- Cyanosis - Costal/sternal indrawing - Tachypnea - rapid breathing - Tachycardia - Nasal Flaring - Stridor - Grunting respiration - Irritability/restlessness

Question 27

Management of Acute Respiratory Failure

Answer 27

- Oxygenation: addressing hypoxemia is the FIRST Priority (Hypoxemia kills quickly while hypercapnia kills slowly) - Supplemental oxygen usually administered - Treating the cause: identify and address underlying cause of respiratory failure. - treating infections, managing COPD or addressing other triggers - Ventilatory Support - alleviate hypercapnia by increasing alveolar ventilation (May involve deep breathing exercises, NIV, or mechanical ventilation in severe cases)

Question 28

Gold standard therapy is?

Answer 28

Intubation and Mechanical Ventilation 1. Positive Pressure ventilation: - delivers air directly into the lungs, improving alveolar ventilation and gas exchange 2. Increased FiO2 delivery: Allows for precise control of oxygen concentration to address hypoxemia 3. Management strategy: preferred for potentially reversible respiratory failure cases 4. Challenging cases: may require special ventilation strategies

Question 29

What is Non-Invasive Ventilation (NIV)?

Answer 29

- Uses a close fitting mask over the nose or mouth to deliver high-flow gas with positive end-expiratory pressure (PEEP) - Benefits: High pressure splints open airways, increases lung volumes, and increases alveolar ventilation. Reduces WOB and may help avoid intubation. - Applications: Effective in managing acute exacerbations of COPD and other forms of acute respiratory failure. May allow avoidance of intubation and mechanical ventilation