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Resp > Lecture 5 - CO2 In Blood > Flashcards

Lecture 5 - CO2 In Blood Flashcards

1
Q

What is myalgia?

A

Muscle aches

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2
Q

What are diffuse rhonchi?

A

Breathing sounds that are non specific cracking sounds

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3
Q

What signs may you see on a chest x-ray with someone who has Covid-19 Pneumonia?

A

Wides spread fluffy shadows

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4
Q

How do widespread fluffy shadows appear on a CT scan in someone with pneumonia COVID 19?

A

White in cross section
Called ground glass opacities

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5
Q

What tests would you order for a patient who you consider to have Covid-19 Pneumonia?

A

ECG
FBC
U+E
Crp
Arterial Blood Gas (ABG)
Urinalysis

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6
Q

What condition would you be worrying about if someone had very high levels of Glucose and Ketones in their urine?

A

Diabetic ketoacidosis

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7
Q

What is the normal pH range for blood plasma?

A

7.35-7.45

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8
Q

How do you treat Diabetic Ketoacidosis?

A

Give insulin

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9
Q

What dangerous condition can develop as a result of Covid-19 Pneumonia?
(Unknown why)

A

Diabetic Ketoacidosis

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10
Q

What is the disease process of having a low blood pH?
How does it do harm to the brain?

A

Enzyme Phosphofructokinase (glycolysis) is pH sensitive
If pH decreases (more acidic) it doesn’t work as well, this means glucose cant be utilised in the brain

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11
Q

What are the clinical consequences of having low blood pH (Acidosis)?

A

Coma
Death in Coma
Drowsiness
Stupor

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12
Q

What is the relationship between H+ conc and pH?

A

As [H+] inc, pH decreases

As [H+] dec, pH inc

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13
Q

What is the ratio of CO2:HCO3- needed to ensure that the pH is maintained in the health physiological range?

A

1:20

1CO2 : 20HCO3-

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14
Q

What are the equations showing why CO2 leads do a decrease in blood pH?

A

CO2 + H2O <—> H2CO3

H2CO3 <—> H+ + HCO3-

So for every CO2 molecule only 1 HCO3- molecule is produced (we need 20 to be made to maintain pH) this leads to the ratio of CO2:HCO3- being off making it more acidic

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15
Q

What are the 3 different methods of CO2 transport needed to ensure the excess H+ ions dont always cause acidosis?

A

Carbamino compounds (30%)

Transported as bicarbonate ions (HCO3-) (60%)

Dissolved in plasma (10%)

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16
Q

What is a carbamino compound?

A

When CO2 binds to haemoglobin to be transported (binds to the amine group)

17
Q

How does CO2 being bound to Hb (carbamino compound help prevent changes in pH?

A

Stops the CO2 being able to enter blood since its trapped in red blood cell

18
Q

How does the formation of carbamino compounds help with gas exchange?

A

Bohr effect

Haldane effect

19
Q

How does the formation of carbamino compounds help with gas exchange? (Bohr effect)

A

Lots of CO2 binds to Hb at highly metabolically active tissues
This stabilises the T state of haemoglobin promoting the release of O2 to the tissues

20
Q

How does the formation of carbamino compounds help with gas exchange? (Haldane effect)

A

When CO2 is given up by Hb at the lungs which puts Hb in more of the R state making it have a higher affinity for oxygen

21
Q

What enzyme in the red blood cell catalyses the dissociation of carbonic acid?

A

Carbonic anhydrase

22
Q

When carbonic acid dissociates in the red blood cell, how does the cell prevent the excess build up of HCO3- ions in the cell?

A

Chloride bicarbonate exchanger
HCO3- moved out Cl- ions moved in

23
Q

How does the oxygenation of haemoglobin affect the binding of H+ to Hb?

A

When Hb deoxygenated more H+ ions can bind

When Hb oxygenated less H+ ions can bind

24
Q

How do bicarbonate ions act to buffer acid?

A

The H+ reacts with HCO3-
Leads to H20 + CO2 -> H+ + HCO3- reaction equilibrium getting pushed to the left

25
Q

What are the 2 organs responsible for regulating the acid base balance in the body?

A

Lungs

Kidneys

26
Q

How do the lungs help regulate the acid base balance?

A

Control rate and depth of breathing to change how much CO2 is in the body

27
Q

How do the kidneys help regulate the acid base balance?

A

Change how much HCO3– (bicarbonate) in the blood

HCO3- made by RBC, this gets released in plasma and then stored in the kidneys

28
Q

What is the relative speed of the kidneys and lungs in terms of helping control the acid base balance?

A

Kidneys = slow control (HCO3- system takes a while)

Lungs = fast control

29
Q

How do the kidneys control acid base regulation?

A

Blood cells make HCO3-

HCO3- conc controlled by kidneys by changing the amount they excrete in the urine

30
Q

Which buffering system is the quickest to respond?

A

Respiratory is faster
Metabolic/renal is slower

31
Q

How does pH change as pCO2 changes in the alveoli/blood?

A

High pCO2 = pH low

Low pCO2 = pH high

32
Q

How do levels of bicarbonate change if levels of pCO2 increase or decrease?

A

Levels of bicarbonate do not change in response to changing levels of CO2

33
Q

How does CO2 dissolving in plasma change depending on the partial pressure of CO2?

A

Higher partial pressure of CO2 means more CO2 dissolves in plasma

34
Q

What is hypocapnia and hypercapnia?

A

Hypocapnia = low CO2 levels

Hypercapnia = high CO2

35
Q

What are the 3 steps to interpreting an Arterial Blood Gas?

A

Look at the pH is it acidosis or alkalosis

Look at pCO2 result to see if the acidosis or alkalosis is due to a respiratory problem

Look at the bicarbonate result to see if its metabolic reaction

36
Q

Look at this patients Arterial Blood Gas and diagnose:

pH: 7.33
PCO2: 4.1kPa (4.5-6)
HCO3-: 16mmol/L (22-26)

A

PH is low therefore acidosis

PCO2 is low so isn’t the cause of the acidosis but HCO3- is low so is the cause of the acidosis

So this is metabolic acidosis which is partially compensated since the pCO2 is low (increased ventilation)

37
Q

Look at this patients Arterial Blood Gas and diagnose:

Pateint is having a panic attack and is hyperventilating

pH: 7.5
PCO2: 4.5kPa (4.7-6)
HCO3-: 25mmol/L (22-26)
PO2 = 14kPa (9.3-13.3)

Is it acute or chronic?

A

Respiratory alkalosis

Its not compensated and its acute

38
Q

Look at this patients Arterial Blood Gas and diagnose:

Long standing COPD
pH: 7.35
PCO2: 8kPa (4.5-6)
HCO3-: 33mmol/L (22-26)
PO2 = 8.2kPa (9.3-13.3)

A

Fully compensated respiratory acidosis

Ph is normal so its fully compensated
And the co2 is high so this shows it a respiratory cause

39
Q

What would a patients arterial blood gas look like in a patient who’s got fully compensated metabolic acidosis?

A

PH = normal
HCO3- = low
PCO2 = low
PO2 = high

The gases are these levels since hyperventilation

Resp (23 decks)

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