Week 8 - Mrs Mitchell

Question 1

Define the general terms tachycardia.

You do not need to include parameters

Answer 1

Tachycardia - increased heart rate
Rapid heartbeat
Faster than normal

Question 2

Define the general terms tachypnea.

You do not need to include parameters

Answer 2

Tachypnea - increased breathing rate

Question 3

For a 70Kg man what is the amount of total body water and how is this calculated?

Answer 3

Body weight x 60%

70Kg x 60% = 42L

Question 4

The concentration of what solute in the blood is important for the increased osmolarity when fluid volume decreases that stimulates the hypothalamus

Answer 4

Sodium

Question 5

If Mrs Michel had been vomitting rather than having diarrhoea what acid base disturbance would she be most likely to have presented with and why?

Answer 5

Metabolic alkalosis (1 mark)

Vomiting leads to the loss of gastric secretions which are rich is hydrochloric acid. (1 mark)

Whenever a hydrogen ion is excreted a bicarbonate ion is gained. (1 mark) in the extracellular space leading to more bicarbonate in the body and therefore alkalosis. (1 mark)

Question 6

Briefly explain how metabolic acidosis is compensated for both by the lungs and the kidneys? (2 marks)

Answer 6

Lungs: Lowering the PCO2 by hyperventilation

Kidney: Adds more H+ (or NH+) to the urine

Question 7

What are some common symptoms of metabolic acidosis?

Answer 7

Headache

Decreased BP

Hyperkalemia (normally with quick onset)

Muscle twitching

Warm, flushed skin

Nausea, Vomiting, Diarrhoea

Changes in LOC (Confusion, drowsiness)

Kussmaul Respirations (compensatory hyperventilation)

Question 8

What are some causes of Metabolic Acidosis?

Answer 8

Severe Diarrhoea
Renal Failure
Shock

Question 9

What is metabolic acidosis?

Answer 9

Decrease ability of the kidney to excrete acid or conserve base

Question 10

What pH should our body stay within?

Answer 10

7.35 and 7.45

Question 11

Why is it important for the pH of the body to be within 7.35 and 7.45?

Answer 11

So enzymes do not denature

Question 12

Mrs Mitchel is 72 years old and lives in a sheltered accommodation flat. She is admitted to hospital with a one week history of severe diarrhoea. She is weak, lethargic and clinically dehydrated. At the hospital a physician associate takes her blood pressure which is 100/60 mm Hg when lying down and this drops to 70/40 mm Hg when she is sitting up. Her radial pulse is weak, but there was tachycardia and tachypnea. There was reduced urine output.

List Mrs Mitchell’s presenting symptoms when admitted

Answer 12

72 years old

• 1 week of severe diarrhoea
• weak, lethargic, clinically dehydrated

Question 13

Mrs Mitchel is 72 years old and lives in a sheltered accommodation flat. She is admitted to hospital with a one week history of severe diarrhoea. She is weak, lethargic and clinically dehydrated. At the hospital a physician associate takes her blood pressure which is 100/60 mm Hg when lying down and this drops to 70/40 mm Hg when she is sitting up. Her radial pulse is weak, but there was tachycardia and tachypnea. There was reduced urine output.

What did the physician’s associate find in the hospital?

Answer 13

BP

110/60mmHg (lying down)
70/40mmHg (sitting)

Tachycardia
Tachypnoea
Reduced urine output

Question 14

What is the definition of tachycardia?

Answer 14

Increased heart rate >100bpm

Question 15

What is the definition of tachypnoea?

Answer 15

Increased respiratory rate >20 per min

Question 16

What is Ringer’s Lactate?

Answer 16

Solution for fluid and electrolyte replacement

Isotonic with blood
Lactate has alkaline effect which can help counteract the acidosis (metabolised into HC03-) in blood serum or in urine

Question 17

What is Creatinine?

Answer 17

Waste molecule generated from metabolism of creatine in muscle

Filtered by kidneys and disposed in urine

Question 18

What is the anion gap?

Answer 18

It checks the levels of acid in your blood

Measurement of the difference - or gap - between the negatively charged and positively charged electrolytes

If the anion gap is too high or too low, may be a sign of a disorder in your lungs, kidneys, other organ systems

Question 19

Summarise the 4 different types of acid-base disturbance

Answer 19

Respiratory acidosis - retain CO2, usually because of hypoventilation (not breathing out enough)

Respiratory alkalosis - blow off too much CO2 hyperventilation (fast breathing)

Metabolic acidosis - retain H+ and excrete HCO3- (e.g. diarrhoea)

Metabolic alkalosis - retain HCO3- and excrete H+ (e.g. vomitting)

Question 20

What acid base disturbance are you likely to have if you have been vomiting?

Answer 20

Metabolic alkalosis

Lose H+ ions in vomitting from the stomach (think about it stomach acid lost, lose H+ ions)

Question 21

What acid base disturbance are you likely to have if you have been diarrhoea?

Answer 21

Metabolic acidosis

Question 22

What acid base disturbance are you likely to have if you have been hyperventilating?

Answer 22

Respiratory alkalosis

Lose too much CO2, CO2 is acidic, so the blood becomes alkaline

Question 23

What acid base disturbance are you likely to have if you have been hypoventilating?

Answer 23

Respiratory acidosis

Retain CO2 and so blood gets acidic

Question 24

What do Mrs Mitchell’s blood work show when she first arrives?

pH - 7.11
pC02 - 16 (35-45mmHg)
HCO3- 5 (22-26mEq/L)

Answer 24

Hyperchloremic (High chloride levels - 118 (98-106)

pH is low 7.11

pCO2 is low - 16 (35-45)
compensatory hyperventilation

HCO3- is very low - 5 (22-26)

Hypokalaemia was very low but then was corrected 2.5 to 4.2 (3.5-5.5)

Question 25

If you see a pH of 7.11 and a pCO2 of 16 (35-45mmHg) what does the patient have?

Answer 25

Acidosis If pCO2 was high it would be respiratory acidosis But because it is low you can see that the respiratory system was trying to counteract the low pH through hyperventilation so it is Metabolic Acidosis

Question 26

What does Mrs Mitchell's blood work show after the Ringer's solution? pH - 7.49 pC02 - 20 (35-45mmHg) HCO3- 15 (22-26mEq/L)

Answer 26

pH is 7.49 Alkalosis pCO2 would be high in acidosis and low in alkalosis, which is in line with the high pH So Respiratory alkalosis Her body didn't compensate yet for the Ringer's solution

Question 27

What are the 3 compensatory mechanisms that help handle changes in pH?

Answer 27

1. Physiologic buffers - a reversible equation where a weak acid is broken down into a base salt or weak base Examples: - Bicarbonate-carbonic acid buffer system - Intracellular protein buffers - Phosphate buffers in the bone 2. Pulmonary compensation - changes in pCO2 driving pH 3. Renal compensation - kidneys excrete or retain HCO3-

Question 28

What are 3 examples of physiological buffers?

Answer 28

Bicarbonate-carbonic acid buffer system Intracellular protein buffers Phosphate buffers in the bone

Question 29

How does pulmonary compensation work?

Answer 29

So when pH is low, increase ventilation gets rid of acidic CO2 and works to increase pH When pH is high, there is a decrease in ventilatory effort, which increases pCO2 (retains acidic CO2) and lowers pH back towards normal

Question 30

How does renal compensation work?

Answer 30

Starts 6 hours after sustained acidosis or alkalosis In acidosis, kidneys excrete H+ and retains HCO3- In alkalosis, kidneys excrete HCO3- and retain H+ in the form of organic acids

Question 31

How long does it take for renal compensation to kick in?

Answer 31

6 hours after sustained acidosis or alkalosis

Question 32

What are the final reserves for acidosis/alkalosis?

Answer 32

Bone Bone can act as a buffer because it has a large reservoir of bicarbonate and phosphate and can buffer a significant acute acid load If patients have low albumin levels, bone density due to malnutrition or chronic disease and anaemic patients, buffering ability is compromised

Question 33

Why does respiratory acidosis occur? Physiological mechanism

Answer 33

The only mechanism is alveolar hypoventilation (pCO2 is above 45mmHg) pH is less than 7.35 Alveolar hypoventilation can occur due to paralysis, brain stem disturbances, patient is sedated, elderly unwell and can't move, respiratory paralysis (Guillain Barre) Pulmonary emphysema, pulmonary oedema, COPD, bronchitis

Question 34

Why does respiratory alkalosis occur? Physiological mechanism

Answer 34

pH is high pCO2 is low (breathed out) Most common cause is due to increased alveolar ventilation (hyperventilation (anxious), hepatic disease, pregnancy, septicaemia, over ventilated in iCU) Paper bag in hyperventilation helps to regulate CO2

Question 35

Why does metabolic acidosis occur? Physiological mechanism

Answer 35

Increase in amount of body acid (excess production of acids or excessive loss of bicarbonate, sodium and potassium) Lactic acidosis Diabetic ketoacidosis Loss of bicarbonate through severe diarrhoea Bicarbonate wasting through kidneys or GI tract

Question 36

What are some signs and symptoms of metabolic acidosis?

Answer 36

Headache Lethargy Anorexia Deep, rapid respirations (Kussmaul) Nausea Diarrhoea Abdominal discomfort (severe acidosis) Coma and dangerous dysrhythmias

Question 37

What ions are involved in the anion gap?

Answer 37

(Na + K) - (Cl + HCO3) As sodium is the most dominant cation can do Na - (Cl + HCO3)

Question 38

What does a normal anion gap indicate in metabolic acidosis?

Answer 38

You have a very high level of Cl- to make up for the low HCO3- in the equation Na - (Cl + HCO3)

Question 39

Why does metabolic alkalosis occur? Physiological mechanism

Answer 39

HCO3- is increased, usually due to an excessive loss of metabolic acids ``` Diuretics Prolonged vomitting Hyperaldosteronism Cushing's syndrome Exogenous steroids ```

Question 40

What are some signs and symptoms for metabolic alkalosis?

Answer 40

Cardiac dysrhythmias as a result of low K Physical weakness Muscle cramping Hyperactive reflexes Tetany Convulsions Confusion

Question 41

Reasons for an elevated anion gap Don't really need to know

Answer 41

Particular medications can cause it to be elevated ``` Methanol, metformin Ethylene glycol Toluene Alcoholic ketoacidosis Lactic acidosis ``` Aminoglycosides, other uremic agents Cyanide, carbon monoxide Isoniazid, iron Diabetic ketoacidosis Generalised seizure-producing toxins ASA or other salicylate Paraldehyde, phenformin

Question 42

Mrs Mitchell's potassium levels were: 2.5 then 4.2 next day (3.5-5.5 mEq/L) Though this is not the case for Mrs Mitchell.. How does Acidosis lead to Hyperkalemia?

Answer 42

Hyperkalemia is when potassium levels are higher than normal H+ ions are taken into the cell from the extracellular fluid, and this is done by exchanging K+ ions to maintain electroneutrality I.V potassium would still be given to these patients early in treatment despite the often elevated serum potassium levels because the cells themselves don't have much K+ in them

Question 43

Mrs Mitchell's sodium levels were: 137 on admission 137 the next day (Normal - 135-147 mEq/L) Explain this?

Answer 43

Normal sodium levels despite everything else changing The kidneys try to keep sodium by exchanging it for excreted H+ or potassium Sodium levels are kept quite constant

Question 44

What is saline responsive?

Answer 44

When you have metabolic alkalosis and you are deciding what treatment to give a patient based on their chloride ion levels in their urine Saline responsive = less 15mmol/L Nonsaline responsive = above 25mmol/L

Question 45

Metabolic acidosis and serum anion gap decreased due to?

Answer 45

Low albumin

Question 46

Metabolic acidosis and serum anion gap increased diagnosis

Answer 46

Lactic acidosis | or Ketoacidosis

Question 47

Metabolic acidosis and normal anion gap = ?

Answer 47

Hyperchloraemic metabolic acidosis Her Chloride levels are in line with this: 118 on admission 114 next day Normal = 98-106 mEq/L

Question 48

What are the three major causes of Hyperchloraemic metabolic acidosis and which one applies to Mrs Mitchell?

Answer 48

Renal tubular acidosis Gastrointestinal losses Chronic hypoventilation GI losses applies to Mrs Mitchell

Question 49

In metabolic acidosis what are the following levels going to be like? pH H+ Primary disturbance (HCO3 or pCO2?) Secondary response (HCO3 or pCO2?)

Answer 49

pH - Low H+ - High Primary disturbance - Low HCO3- Secondary response - Low pCO2

Question 50

In metabolic alkalosis what are the following levels going to be like? pH H+ Primary disturbance (HCO3 or pCO2?) Secondary response (HCO3 or pCO2?)

Answer 50

pH - High H+ - Low Primary disturbance - High HCO3- Secondary response - High pCO2

Question 51

In respiratory acidosis what are the following levels going to be like? pH H+ Primary disturbance (HCO3 or pCO2?) Secondary response (HCO3 or pCO2?)

Answer 51

pH - Low H+ - High Primary disturbance - High pCO2 Secondary response - High HCO3

Question 52

In respiratory alkalosis what are the following levels going to be like? pH H+ Primary disturbance (HCO3 or pCO2?) Secondary response (HCO3 or pCO2?)

Answer 52

pH - High H+ - Low Primary disturbance - Low pCO2 Secondary response - Low HCO3

Question 53

Explain generally renal compensation in acidosis/alkalosis

Answer 53

So you secrete or reabsorb H+ or HCO3- in the collecting duct in the kidneys So you urinate one of the ions out to compensate for what is going on in the body Longer term solution

Question 54

What do the Type A intercalated cells in the kidney's collecting duct do? In what conditions?

Answer 54

In acidosis The Type A intercalated cells Excretes: H+ Reabsorbs: HCO3- and K+

Question 55

What do the Type B intercalated cells in the kidney's collecting duct do? In what conditions?

Answer 55

In alkalosis The Type B intercalated cells Excretes: HCO3- and K+ Reabsorbs: H+

Question 56

How many ml is Ringers fluid?

Answer 56

1L

Question 57

What treatment is Mrs Mitchell given?

Answer 57

IV Lactated Ringer's fluid | Potassium supplementation

Question 58

What is going on in the next day after Mrs Mitchell is admitted? ``` Sodium 137 (135-147mEq/L) Next day: 137 ``` Potassium 2.5 (3.5-5.5 mEq/L) Next day: 4.2 ``` Chloride 118 (98-106mEq/L) Next day: 114 ``` ``` Bicarbonate 5 (22-26mEq/L) Next day: 15 ``` Creatinine 3.1 (0.6-1.1mg/dL women) Next day: 2.0 Anion gap 10 (Less than 11mEq/L) Next day: 8 pH 7.11 (7.35-7.45) Next day: 7.49 ``` pCO2 16 (35-45mmHg) Next day: 20 ```

Answer 58

So she came in with metabolic acidosis (Primary problem is HCO3- lost through diarrhoea) So you can see the Bicarbonate is increasing :D pCO2 is still much lower than predicted which means she is still hyperventilating This results in respiratory alkalaemia This is because the central chemoreceptors in the brain are slow to respond to the reversal in bicarbonate and so you still see compensatory hyperventilation Bicarbonate will slowly enter the brain over 12-24 hours and central chemoreceptor inhibition will be progressively inhibited pCO2 back to normal and normal breathing lags behind the increase in bicarbonate

Question 59

What is the key equation of buffering in the blood?

Answer 59

HCO3- + H+ > H2CO3 > CO2 + H20

Question 60

What 3 organs regulate fluid balance?

Answer 60

Brain Adrenal glands Kidneys

Question 61

What is the process that happens in the body when the fluid volume decreases?

Answer 61

Concentration of sodium increases in the blood (increased osmolarity) Hypothalamus has osmoreceptors Stimulates posterior pituitary to release ADH ADH goes to the kidneys and they retain water (more concentrated urine, water returned to ECF) Adrenal glands secrete aldosterone in response to low BP (retain fluid)

Question 62

How much of the Total Body Water is the Extracellular Fluid Volume?

Answer 62

1/3

Question 63

How much of the Total Body Water is the Intracellular Fluid Volume?

Answer 63

2/3

Question 64

What are the primary components of the extracellular fluid?

Answer 64

``` Interstitial Fluid (3/4) Plasma (1/4) Transcellular Fluid (rest around 0.5L) ```

Question 65

What is the recommended daily intake of fluid?

Answer 65

2.5 L

Question 66

What makes up our intake of fluid?

Answer 66

Drink 1.6L Food 0.7L Metabolic water 0.2L

Question 67

What makes up our outtake of fluid?

Answer 67

``` Feces (0.2L) Expired air (0.3L) Cutaneous transpirational (0.4L) Sweat (0.1L) Urine (1.5L) ```

Question 68

What is the daily output of fluid in L?

Answer 68

2.5L

Question 69

What are the two types of fluid that patients can get for rehydration?

Answer 69

Crystalloid fluids - water with electrolytes added to it (what Mrs Mitchell was given) Colloid fluids - bigger molecules so they stay in blood vessels and water is drawn into the blood vessels (e.g. through trauma and scarring)

Question 70

Different reasons for dehydration?

Answer 70

(Sodium or water loss) Vomitting and diarrhoea Inadequate fluid intake Low-sodium diet or no sodium intake Diabetes insipidus (rare)

Question 71

Symptoms for dehydration

Answer 71

``` Skin turgor Hypovolemia Tachycardia Weak pulse Postural hypotension Confusion ``` Also: thirst, dry skin, sticky or dry mucous membranes, weight loss, concentrated urine

Question 72

What is a minimum urine output required for kidney function?

Answer 72

30ml per hour

Question 73

What is the definition of dehydration?

Answer 73

Lost 1% of body mass

Question 74

When does performance become impaired with water loss?

Answer 74

Loss 2% in body weight

Question 75

What are different effects of water loss on performance?

Answer 75

Loss 1% body weight - dehydration Loss 2% body weight - impaired performance Loss 4% body weight - capacity for muscular work reduced Loss 6% body weight - heat exhaustion Loss 8% body weight - hallucination Loss 10% body weight - circulatory collapse and heat stroke

Question 76

ROME?

Answer 76

Respiratory Opposite Metabolic Equal In terms of the acidosis and alkalosis

Question 77

What does high creatinine indicate? Mrs Mitchel On admission = 3.1 Next day = 2.0 Normal = 0.6-1.1mg/dL (women)

Answer 77

Decreased Renal Function

Question 78

Properties of crystalloid fluids?

Answer 78

Saline plus electrolytes Remain longer in ECF Isotonic