Lab 2- Acid-base and Blood Gas Analysis

Question 1

Isohydria meaning?

Answer 1

Concentration of H ions

Question 2

Why is stability of isohydria important?

Answer 2

Essential for cell membranes
Enzyme activity

Any change in pH may lead to electrolyte imbalance, and cause changes in muscle irritability

Question 3

What is a buffer?

Answer 3

A solution that can resist change in pH when small amount of strong acids/base is added

Question 4

Why is buffer systems important?

Answer 4

Because reactions in the body produced H ions, more rapidly than the body can eliminate, this can lead to change in pH.

intra and extracellular buffer systems. Carbonic acid and bicarbonate buffer systems.

Question 5

Most important buffer systems

Answer 5

Blood plasma
RBC
Tissue cells

Question 6

What are the vital buffer systems?

Answer 6

Kidneys and lungs

Question 7

Hypercapnea meaning?

Answer 7

Excess of CO2

Question 8

What is Kussmaul breathing?

Answer 8

Normal frequency breathing but very deep inspiration and expiration

Question 9

Why do we evaluate acid/base levels?

Answer 9

Routine test in emergency situations
Info about acid-base status, function of vital buffer systems.

Acid-base analyzers are complex devices. They also measure blood-gas parameters, electrolytes and hemoglobin, hematocrit, lactate glucose

Question 10

If we want to investigate respiratory function, what do we need?

Answer 10

Arterial blood

Question 11

What do we need if we want to investigate metabolic status?

Answer 11

Either venous or arterial blood

Question 12

What can contaminate your sample?

Answer 12

Air!
Will increase partial CO2 pressure

Samples should not be stored more than 30 min. In 0-4 degrees

Question 13

What is ionselective electrodes (ISE) used for ?

Answer 13

To measure pH and CO2

Based on this HCO3 and ABE is calculated

Question 14

What is solubility of gasses dependent on ?

Answer 14

Temperature

Question 15

PH of blood

Answer 15

7.35-7.45

Question 16

pCO2 pressure

Answer 16

40 mmHg

Question 17

HCO3-

Answer 17

21-24 mmol/l

Question 18

ABE (actual base excess)

Answer 18

-/+ 3-5 mmol/l

Question 19

TCO2

Answer 19

23-30 mmol/l

Question 20

SBE (standard base excess)

Answer 20

-/+ 3 mmol/l

Question 21

How do you evaluate AB state?

Answer 21

pH!

Acidosis = <7.4
Alkalosis= >7.4

Compensated between 7.35-7.45
Decompensated below 7.35 or above 7.45

Question 22

Primary change in pCO2 meaning ?

Answer 22

Primary respiratory

Question 23

Predominant change in ABE or HCO3 meaning?

Answer 23

Primary metabolic

Question 24

Impaired gas exchange in lungs cause?

Answer 24

When pCO2 pressure is above 40 mmHg more of it binds to water and forms carbonic acid.
Hence increase in pCO2 is called a “shift in acidic” direction
During impaired gas exchange;
Remaining high CO2 in lungs binds to H2O, and shifts pH to acidosis

= respiratory acidosis

Question 25

What happens to pH during hyperventilation ?

Answer 25

Too much CO2 is exhaled, will cause elevation of the pH, respiratory alkalosis !

Question 26

What might change the metabolic parameters HCO3- and ABE ?

Answer 26

Metabolic process or kidney malfunction creating a change in pH. Ex. Metabolic formation of lactic acid - = metabolic acidosis

Question 27

What causes the shift in pH/acid-base disturbance ?

Answer 27

The primary process always.! It’s shift is in the same direction as the pH.

Question 28

Mixed acidosis means?

Answer 28

When all the parameters are shifted in the same direction as the pH! Usually in advanced acidosis

Question 29

How do you know if there is visible compensatory effort?

Answer 29

If either the respiratory or the metabolic parameters is shifted in the opposite direction of the pH.

Question 30

Metabolic acidosis causes?

Answer 30

- HCO3- loss: diarrhea, kidney tubular disease - Increased acid intake: fruits, acidic silage, overdose of acidifying drugs - increased acid production: lactic acid production, anaerobic glycolysis, anorectic/weak animals - cattle: grain overdose leading to VFA overproduction - increased ketogenesis leading to ketosis due to diabetes mellitus or starvation - decreased excretion: renal failure - ion exchange: hyperkalaemia - some xenbiotic: ethylene-glycol toxicosis

Question 31

Effects of metabolic acidosis?

Answer 31

- Kassmaul breathing: hyperventilation - hypercalcaemia - vomiting, depression - hyperkalaemia - urine: titrable acidity increases

Question 32

Treatment of metabolic acidosis ?

Answer 32

Adequate ventilation | If pH is below 7.2 = infusion, amount given is calculated by ABE

Question 33

What is anion gap useful for?

Answer 33

Determine the cause of metabolic acidosis Determine whether metabolic acidosis is due to primary HCO3- loss or accumulation of organic acids

Question 34

Causes of metabolic alkalosis?

Answer 34

- Increased alkaline intake: overdose of barbiturates or feeding rotten food - increased ruminate alkaline production - decreased hepatic ammonia metabolism (liver failure) - increased acid loss: vomiting, gastric dialation volvulus syndrome and abomasal displacement - ion exchange: hypokalaemia

Question 35

Effects of metabolic alkalosis ?

Answer 35

``` Breathing depression - hypoventilation Muscle weakness Hypocalcaemia Ammonia toxicosis Arrhythmia, biphasic P, QT increases and flat T and U wave Paradoxical aciduria ```

Question 36

Treatment of metabolic alkalosis ?

Answer 36

Treat underlying electrolyte imbalance

Question 37

Respiratory alkalosis causes?

Answer 37

- Upper airway obstruction - pleural cavity disease: pneumothorax, pleural effusion - pulmonary disease: severe pneumonia, pulmonary oedema, diffuse lung metastasis, pulmonary lung thromboembolism - depression of central control of respiration - neuromuscular depression of respiratory muscles - muscle weakness - cardiopulmonary arrest

Question 38

Effects of respiratory acidosis?

Answer 38

Dyspnoea, cyanosis, suffocation, muscle weakness, tiredness

Question 39

Treatment of respiratory acidosis?

Answer 39

Assisting ventilation Treatment of the cause: ex. Diuretic treatment Specific cardiogenic treatment Mildly anxiolytics/sedating drug

Question 40

Respiratory alkalosis causes ?

Answer 40

- increased loss of CO2 - hyperventilation - excitation - forced ventilation - epileptiform seizures - fever, hyperthermia - interstitial lung disease

Question 41

Effects of respiratory alkalosis?

Answer 41

Hyperoxia, increased pCO2 | Increased elimination of HCO3- by the kidneys

Question 42

Treatment of respiratory alkalosis?

Answer 42

Anxiolytic or mild sedative drug | Increase the pCO2 level by closing nostrils