Respiratory Alkalosis and Failure

Question 1

What causes Resp Alkalosis?

Answer 1

Hyperventilation

Respiratory alkalosis occurs when high levels of carbon dioxide disrupt the blood’s acid-base balance

Question 2

Resp alkalosis ABG

Answer 2

Increased pH
Decreased CO2

pH > 7.45
PaCO2 <35mmHg

Question 3

Respiratory alkalosis with metabolic compensation

Answer 3

Increased pH
Decreased CO2
Decreased HCO3-

pH > 7.45
PaCO2 <35mmHg
HCO3 <18 mEq/l

Question 4

Respiratory acidosis

Answer 4

Decreased pH
Increased CO2

pH < 7.45
PaCO2 > 45mmHg

Question 5

Respiratory Acidosis with metabolic compensation

Answer 5

Decreased pH
Increased CO2
Increased HCO3-

pH < 7.45
PaCO2 > 45mmHg
HCO3 > 24 mEq/l

Question 6

What causes respiratory acidosis?

Answer 6

Failure of ventilation and accumulation of carbon dioxide.

The primary disturbance is an elevated arterial partial pressure of carbon dioxide (pCO2)

Question 7

Type One respiratory failure stats

Answer 7

PaO2 <8 kPa; PaCO2 Normal

Question 8

Cause of type one respiratory failure

Answer 8

This is due to a ventilation- perfusion (V/Q) mismatch.

Asthma

Congestive Cardiac Failure

Pulmonary embolism

Pneumonia

Pneumothorax

Question 9

Type two resp failure

Answer 9

PaO2 < 8 kPa; PaCO2> 6 kPa

Question 10

Cause of Type Two Respiratory Failure

Answer 10

This is due to alveolar hypoventilation. This means that the lungs fail to effectively oxygenate and blow off carbon dioxide.

Obstructive lung diseases – Chronic obstructive pulmonary disease

Restrictive lung diseases - idiopathic pulmonary fibrosis

Depression of the respiratory center – opiates

Neuromuscular disease – Guillan-Barre syndrome, motor neuron disease

Thoracic wall disease – rib fracture

Question 11

Normal ABG numbers

Answer 11

pH: 7.35 – 7.45
PaCO2: 4.7 – 6.0 kPa || 35.2 – 45 mmHg
PaO2: 11 – 13 kPa || 82.5 – 97.5 mmHg
HCO3–: 22 – 26 mEq/L
Base excess (BE): -2 to +2 mmol/L

Question 12

Determining hypoxia from ABG

Answer 12

PaO2 should be >10 kPa (75mmHg) when oxygenating on room air in a healthy patient.

If the patient is receiving oxygen therapy their PaO2 should be approximately 10kPa less than the % inspired concentration FiO2 (so a patient on 40% oxygen would be expected to have a PaO2 of approximately 30kPa /225mmHg).

Question 13

Hypoxaemia

Answer 13

If PaO2 is <10 kPa (75mmHg) on air, a patient is considered hypoxaemic.

If PaO2 is <8 kPa (60mmHg) on air, a patient is considered severely hypoxaemic and in respiratory failure.

Question 14

Type 1 v type 2 resp failure

Answer 14

Type 1 respiratory failure involves hypoxaemia (PaO2 <8 kPa / 60mmHg) with normocapnia (PaCO2 <6.0 kPa / 45mmHg).

Type 2 respiratory failure involves hypoxaemia (PaO2 <8 kPa / 60mmHg) with hypercapnia (PaCO2 >6.0 kPa / 45mmHg).