Acid base (respiratory implications)

Question 1

What are the pathologies related to oxygen depletion?

Answer 1

1) Cytotoxic hypoxia

2) Mitochondriopathy

3) Chronic hypoxia

4) Others

Question 2

What constitues the buffer system that maintains the pH?

Answer 2

7.36-7.44

1) Immediate: The lungs

2) Late: The Kidneys

Question 3

How to check if the pH is normal or not and what caused it is it respiratory or metabolic?

Answer 3

if it is lower than 7.36-7.44, then it is acidosis, if it is higher then it is alkalosis. Then to know if respiratory or metabolic, check to see if HCO3- is increased or CO2 is reduced for alkalosis, you will only have one not both, opposite for acidosis. If the other variable does not change then it is uncompensated, if it changes then it is compensated (e.g., pH higher than 7.5, high HCO3- = metabolic alkalosis, PCO2 is either not affected (uncompensated), or increased (compensated))

Question 4

What are the different ways by which we control our pH?

Answer 4

1) The chemical acid-base buffering (mediated by the body fluid)

2) The respiratory center (removes CO2)

3) The kidneys (excretes acid/alkaline urine)

Question 5

What are the two compounds that the pH depends upon?

Answer 5

1) CO2 (controlled by the lungs)

2) HCO3- (controlled by the kidneys)

pH = k + Kidney/Lungs

• Diseases lung will decrease the buffering efficacy

Question 6

Describe the homeostatic mechanism of the pH

Answer 6

1) Sensor: in the aorta (chemoreceptors in the aortic and carotid bodies)

2) Medulla: Breathing control center & chemoreceptors in the medulla oblongata

3) Nerve signals are then sent to the intercostal muscles and the diaphragm

Question 7

What is respiratory alkalosis?

Answer 7

When oxygen levels are reduced this will induce hypoxia which will then induce dyspnea and hyperventilation (respiratory alkalosis)

• Due to the metabolism getting affected there will be an anaerobic metabolism which will lead to lactic acidosis

Question 8

What is hypoxia?

Answer 8

Lack of oxygen in the tissues

Question 9

What is hypoxemia?

Answer 9

• Deficiency of oxygen in the blood where the arterial PO2 is <80 mmHg

Question 10

What is dysoxia?

Answer 10

The lack of oxygen utilization by the tissues

Question 11

When does hypoxia occur while oxygen in the blood is normal?

Answer 11

In carbon monoxide poisoning

Question 12

What is the mechanism of action of the kidneys to maintain the pH?

Answer 12

• It regulates the pH by secreting Hydroen ions and reabsorbing HCO3- and producing HCO3-

1) During alkalosis, excess HCO3- is excreted increasing the concentration of H+ in the circulation

2) During acidosis the kidneys will reabsorb all of the bicarbonate and produce some to increase the pH

Question 13

What are the normal values of the blood?

Answer 13

1) pH (7.36-7.44)

2) PaCO2 (35-45)

3) HCO3- (22-26)

4) PaO2 (75-95)

5) O2 sat (>94)

Question 14

What are the different causes of respiratory acidosis?

Answer 14

• In respiratory acidosis, CO2 is high (due to respiratory depression in cases of pneumonia, emphysema, etc, Drugs such as opioids can cause respiratory depression)

1) COPD

2) Neuromuscular disease

3) Respiratory center depression

4) Late Acute Respiratory distress syndrome

5) Inadequate mechanical ventilation

6) Sepsis

7) Burns

8) Excess bicarb intake

Question 15

What are the signs and symptoms of respiratory acidosis?

Answer 15

• The patient will show red flushness as CO2 causes vasodilation.

1) Dyspnea

2) Disorientation

3) Coma

4) Dysrhythmias

5) Hypokalemia

6) Hyperemia

Question 16

How to treat respiratory acidosis?

Answer 16

1) Treat the underlying cause

2) Supportive ventilation

3) Correct the electrolyte imbalance

4) IV of sodium bicarbonate

Question 17

What are the clinical manifestations of respiratory alkalosis?

Answer 17

1) Anxiety

2) Fever

3) ASA overdose

4) Trauma

5) Pain

6) Emphysema and pneumonia

Question 18

What are the clinical manifestations of respiratory alkalosis?

Answer 18

• Alkalosis is EXCITATORY. It will cause twitches and maybe even convulsions

1) SOB

2) Tachycardia

3) Numbness/Tingling of extremities

4) Seizures

5) Syncope

6) Coma

Question 19

What is the treatment of respiratory alkalosis?

Answer 19

1) Treating the underlying cause

2) Assist the patient to breath

3) Breathing in a paper bag

4) Sedation

Question 20

How to determine if the acidosis or alkalosis is respiratory or metabolic?

Answer 20

Look at PCO2 (respiratory if affected) and HCO3- (metabolic if affected)

• You must know the normal values

Question 21

What are the compensatory mechanisms of the body to alkalosis and acidosis?

Answer 21

1) Respiratory compensation In case of metabolic acidosis & alkalosis

2) Renal compensation in case of respiratory acidosis and alkalosis

Question 22

What is COPD?

Answer 22

Chronic obstructive pulmonary disease, is a irreversible airflow limitation during forced expiration, which might result from a loss of elastic recoil or increased resistance of the conducting airways

Patients with COPD will have a high CO2 in the blood and thus a lower pH

Question 23

Describe the mucus of a COPD patient

Answer 23

In chronic bronchitis the sputum is mucoid and macrophages are the predominant cell type

If exacerbated the sputum becomes purulent due to the presence of neutrophils

Question 24

What microorganisms are cultured in exacerbated COPD?

Answer 24

1) S.Pneumonia

2) Haemophilus Influenza

• In severe obstruction:

1) Maroxella catarhalis

2) Pseudomonas aeruginosa

Question 25

What will happen to the acid-base in congestive heart failure?

Answer 25

1) Hypoxemia due to lung congestion

2) Hypocapnia

3) Low bicarb, low diffusion, and thus lactic acidosis

The heart’s main function is to pump blood-rich oxygen to tissues, which metabolize it and produce CO2. In heart failure, there is low cardiac output and lung congestion. When the lung is congested, it will be rigid and restrictive and patient will be tachypneic and low PCO2 with a high lactate, due to low cardiac output and oxygen delivery, thus the tissue switches to anaerobic metabolism, which produces lactate as a by-product. ABG is also important in these patients, not just respiratory disease patients. So, ABG is important in diseases of the cardiopulmonary and renal systems, as well as GIT, liver, and mitochondrial disease.