Critical Care and the unwell patient post surgery

Question 1

What is the definition of shock?

1 - lack of respiratory drive
2 - failure of circulation to provide adequate perfusion of tissues
3 - increases tachycardia
4 - syncope

Answer 1

2 - failure of circulation to provide adequate

• various classes ranging from I - IV

Question 2

Acid-base disorders is a pathologic change in CO2 partial pressure (Pco2) or serum bicarbonate (HCO3−) that typically produce abnormal arterial pH values. What is the normal pH of blood?

1 - 7.30 - 7.45
2 - 7.20 - 7.45
3 - 7.35 - 7.45
4 - 7.34 - 7.65

Answer 2

3 - 7.35 - 7.45

<7.35 = acidosis
<7.45 = alkalosis

Question 3

Acid-base disorders is a pathologic change in CO2 partial pressure (Pco2) or serum bicarbonate (HCO3−) that typically produce abnormal arterial pH values. If the PCO2 is >6.0 kPa (45mmHg) is this respiratory acidosis or alkalosis?

Answer 3

• respiratory acidosis

Question 4

Acid-base disorders is a pathologic change in CO2 partial pressure (Pco2) or serum bicarbonate (HCO3−) that typically produce abnormal arterial pH values. If the PO2 is <4.7 kPa (35mmHg) is this respiratory acidosis or alkalosis?

Answer 4

• respiratory alkalosis

Question 5

Bases are HCO3-
Acids are CO2

What is the normal range for a base excess?

1 - +1 to +2
2 - -1 to +2
3 - -2 to +2
4 - 0 to +2

Answer 5

3 - -2 to +2

• normal we would expect, but the range can be - or +2

Question 6

Acid-base disorders is a pathologic change in CO2 partial pressure (Pco2) or serum bicarbonate (HCO3−) that typically produce abnormal arterial pH values. If the HCO3- is <24mmol/l or a base excess (BE) < -2 is this metabolic acidosis or alkalosis?

Answer 6

• metabolic acidosis

Question 7

Acid-base disorders is a pathologic change in CO2 partial pressure (Pco2) or serum bicarbonate (HCO3−) that typically produce abnormal arterial pH values. If the HCO3- is >24mmol/l or a base excess (BE) > +2 is this metabolic acidosis or alkalosis?

Answer 7

• metabolic alkalosis

Question 8

Is a metabolic alkalosis or acidosis compensated for quickly by respiration or renal function?

Answer 8

• respiratory is rapid response
• changes in CO2 retention or expiration

Question 9

Is a metabolic alkalosis or acidosis compensated for slowly by respiration or renal function?

Answer 9

• renal function is slow
• retains or excretes HCO3-

Question 10

Which of the following does NOT typically cause respiratory alkalosis?

1 - PE
2 - pneumonia
3 - sepsis
4 - pain
5 - vomiting

Answer 10

5 - vomiting

• all others cause respiratory alkalosis due to hyperventilation

Question 11

Which of the following does NOT typically cause respiratory acidosis?

1 - severe pneumonia
2 - sedation/opioids
3 - ontubdation (drowsy)
4 - diarrhoea

Answer 11

4 - diarrhoea

• all others reduce respiration and therefore retain CO2

Question 12

Which of the following does NOT typically cause metabolic acidosis?

1 - hypoperfusion
2 - kidney failure
3 - vomiting
4 - gut dysfunction

Answer 12

3 - vomiting

Question 13

Which of the following cause metabolic alkalosis?

1 - hypoperfusion
2 - kidney failure
3 - vomiting
4 - gut dysfunction

Answer 13

3 - vomiting

• loss of HCL so too much HCO3-

Question 14

The oxygen-hemoglobin dissociation curve shows the relationship between haemoglobin saturation with O2 (SO2) and partial pressure of O2 (PO2).

Partial pressure is a measurement of the individual components of a mixture of gas. Therefore if PO2 is high then there is more change for more O2 to bind with haemoglobin.

Answer 14

Haemoglobin absorbs different wavelengths of light depending on the degree of saturation. This is the basis of how pulse oximetry works.

Question 15

Which of the following is the main driver of haemoglobin saturation?

1 - iron
2 - haematocrit
3 - PO2
4 - copper

Answer 15

3 - PO2

• more O2 means more O2 to bind to haemoglobin

Question 16

The oxygen-hemoglobin dissociation curve is plotted as a sigmoidal shape. What relevance does this have?

1 - less O2 affinity as O2 binds to haemoglobin
2 - increased O2 affinity as O2 binds to haemoglobin
3 - no relationship

Answer 16

2 - increased O2 affinity as O2 binds to haemoglobin

• essentially easier to bind the 4th O2 molecule than the first O2 molecules

Question 17

What is typically deemed an acceptable % saturation of O2 to haemoglobin that is sufficient to ensure adequate tissue perfusion?

1 - 90%
2 - 94%
3 - 75%
4 - 60%

Answer 17

2 - 94%

• roughly = to 60mmHg

Question 18

If a patient switches to anaerobic metabolism this can lead to an increase in what being released and diffusing into the blood?

1 - CO2
2 - O2
3 - Cl-
4 - K+

Answer 18

1 - CO2

• causes increased PCO2
• more CO2 binds to RBCs
• carbonic anydrase converts H20 and CO2 into HCO3- and H+

Question 19

If a patient switches to anaerobic metabolism this can lead to an increase in CO2 being released and diffusing into the blood. This is absorbed by RBCs, which create HCO3- and H+ due to carbonic anhydrase. What then happen to the pH?

1 - increases
2 - remains constant
3 - decreases

Answer 19

3 - decreases

Question 20

If we look at the oxygen-hemoglobin dissociation curve, it will shift to the right in times of stress due to increased CO2, reduce pH and increase temperatures What affect does this have on RBCs affinity for O2?

Answer 20

• reduces
• means O2 can be quickly offloaded where required

Question 21

2,3-diphosphoglycerate (2,3 DPG) acid present in RBCs and is a metabolic byproduct of glycolysis in RBCs. Does 2,3 GPG increase or decrease in times of stress or hypoxia?

Answer 21

• increase production in RBCs
• decreases where O2 levels are high, like near the lungs

Question 22

2,3-diphosphoglycerate (2,3 DPG) acid present in RBCs and is a metabolic byproduct of glycolysis in RBCs. 2,3 GPG increase during times of stress or hypoxia. Does 2,3 DPG increase or decrease haemoglobin affinity for O2?

Answer 22

• decrease
• good as it allows O2 to deposited where it is needed most

Question 23

In the oxygen-hemoglobin dissociation curve, it can shift to the right in the following:

• increased CO2
• increased temperature
• increased 2,3 DPG
• decreased pH

This causes an reduced affinity for O2 to RBCs. Does this mean a higher or lower partial pressure of O2 is required to saturate haemoglobin?

Answer 23

• higher PO2 is required

Question 24

In the oxygen-hemoglobin dissociation curve, it can shift to the right in the following:

• decreased CO2
• decreased temperature
• decreased 2,3 DPG
• increased pH

This causes an increased affinity for O2 to RBCs. Does this mean a higher or lower partial pressure of O2 is required to saturate haemoglobin?

Answer 24

• lower PO2 is required

Question 25

How much less should arterial PaO2 be than inspired O2 concentration? 1 - 50 2 - 25 3 - 10 4 - 1

Answer 25

3 - 10 - O2 is diluted in alveolus with Co2 and H2O - if patient is given 30 or 50% O2 it will give a PaO2 of around 20 and 40kPa respectively

Question 26

If we know that oxygen is diluted by approximately 10 in the alveolus with CO2 and H2O and a patient is given 50% oxygen, but has a PaO2 of 15 kPa, what does that suggest? 1 - inspired O2 is not 50% 2 - patients mask is ill fitting 3 - patient has severe respiratory problems

Answer 26

3 - patient has severe respiratory problems - inability to oxygenate

Question 27

The VQ or ventilation/perfusion ratio can tell us about the lung function. - alveolar ventilation = O2 reaching alveolar (L/min) - perfusion = pulmonary blood flow reaching arteries and capillaries around alveolar (L/min) What is the normal VQ in a patient who is healthy and stood upright? 1 - 0.5 2 - 0.8 3 - 1.2 4 - 2.0

Answer 27

2 - 0.8 normal V = 4L/min normal Q = 5L/min 4/5 = 0.8

Question 28

The VQ or ventilation/perfusion ratio can tell us about the lung function. - alveolar ventilation = O2 reaching alveolar (L/min) - perfusion = pulmonary blood flow reaching arteries and capillaries around alveolar (L/min) These can be caused by shunts, which is a perfused lung but no ventilation. Here blood is diverted away from the non-ventilated alveoli. Which of the following is NOT an example of this? 1 - COPD 2 - cystic fibrosis 3 - emphysema 4 - PE

Answer 28

4 - PE - the patient would have a normal Q but a low V - patient has a POOR response to O2

Question 29

The VQ or ventilation/perfusion ratio can tell us about the lung function. - alveolar ventilation = O2 reaching alveolar (L/min) - perfusion = pulmonary blood flow reaching arteries and capillaries around alveolar (L/min) These can be caused by increased dead space. Here the lungs are being ventilated but there is less or no blood blood. Which of the following is NOT an example of this? 1 - gas embolism 2 - hypovolaemia 3 - emphysema 4 - PE

Answer 29

3 - emphysema - the patient would have a normal V but a low Q - patient has a GOOD response to O2

Question 30

If a patients has a pulmonary embolism this can block the pulmonary artery and create an acute increase in dead space (non-perfused lung tissue). Which of the following is NOT a symptom a patient is likely to present with if they have a PE? 1 - bradycardia 2 - dyspnoea (difficulty breathing) 3 - chest pain 4 - haemoptysis 5 - cough 6 - fever

Answer 30

1 - bradycardia - it would cause tachycardia

Question 31

What blood marker can be used to indicate deep vein thrombosis, which can lead to a PE? 1 - troponin 2 - D-dimer 3 - atrial natriuretic peptide 4 - CRP

Answer 31

2 - D-dimer - a fibrin degradation product

Question 32

Aspiration pneumonia can occur post operatively. Is this dangerous?

Answer 32

- yes - high rates of mortality

Question 33

While in hospital patients may develop hospital acquired pneumonia (HAP) within 72 hours following admission. Which strain of bacteria is most likely to cause this? 1 - E.coli 2 - staphylococcus 3 - streptococcus 4 - klebsiella

Answer 33

2 - staphylococcus

Question 34

While in hospital patients may develop hospital acquired pneumonia (HAP) within 72 hours following admission caused by staphylococcus. Which of the following is NOT a symptom of perioperative pneumonia? 1 - cough 2 - dyspnoea 3 - hypothermia 4 - lethargy 5 - green/yellow sputum

Answer 34

3 - hypothermia - would normally cause fever

Question 34

While in hospital patients may develop hospital acquired pneumonia (HAP) within 72 hours following admission caused by staphylococcus aureus 3 - streptococcus 4 - klebsiella

Question 35

Which of the following is NOT a sepsis 6? 1 - give fluids 2 - give analgesia 3 - give oxygen 4 - take urine count 5 - take blood lactate 6 - take 2 blood cultures

Answer 35

2 - give analgesia - we should give antibiotics

Question 36

If a patient has a haemorrhage, does their Hb drop immediately?

Answer 36

- no

Question 37

If a patient needs blood, typically which blood is given? 1 - group A 2 - group B 3 - group AB 4 - group O

Answer 37

4 - group O - no antigens, so anyone can have it - people with O blood can ONLY receive O blood type though

Question 38

If a patient requires resuscitation fluids, how much and how quickly should it be given typically? 1 - crystalloid bolus of 500ml with Na+ (130-154mmol) over 15 mins 2 - crystalloid bolus of 250ml with Na+ (135-155mmol) over 15 mins 3 - crystalloid bolus of 500ml with Na+ (135-155mmol) over 30 mins 4 - crystalloid bolus of 150ml with Na+ (150-160mmol) over 15 mins

Answer 38

1 - crystalloid bolus of 500ml with Na+ (135-155mmol) over 15 mins

Question 39

If a patient requires maintenance fluids, how much and how quickly should it be given typically? 1 - 2.5 - 3ml/kg/day of water 2 - 2.5 - 30ml/kg/day of water 3 - 25 - 30ml/kg/day of water 4 - 25 - 3ml/kg/day of water

Answer 39

3 - 25 - 30ml/kg/day of water - 1mmol/kg/day of Na+. K+ and chloride - 50-100g glucose

Question 40

Top calculate mean arterial pressure (MAP), we use the formula: MAP - central venous pressure (CVP), which is = to cardiac output x systemic vascular resistance. Why is MAP important? 1 - perfusion of the heart 2 - pressure around renal arteries 3 - perfusion pressure of organs

Answer 40

3 - perfusion pressure of organs

Question 41

How do we calculate mean arterial pressure (MAP) in a clinical setting? 1 - diastolic x 2 add systolic BP 2 - diastolic BP add systolic BP 3 - diastolic BP add 1/3 of systolic BP

Answer 41

3 - diastolic BP add 1/3 of systolic BP

Question 42

What is hypovolaemic shock? 1 - afterload reduction and possible bradycardia 2 - increased preload, decreased contractility and increased afterload 3 - preload reduced with compensatory increase in afterload 4 - afterload reduction due to vasodilation and increased HR

Answer 42

3 - preload reduced with compensatory increase in afterload - caused by blood loss, diarrhoea, burns or tissue oedema

Question 43

What is septic shock? 1 - afterload reduction and possible bradycardia 2 - increased preload, decreased contractility and increased afterload 3 - preload reduced with compensatory increase in afterload 4 - afterload reduction due to vasodilation and increased HR

Answer 43

4 - afterload reduction due to vasodilation and increased HR - caused by endotoxins or exotoxins and mediated by immune response

Question 44

What is cardiogenic shock? 1 - afterload reduction and possible bradycardia 2 - increased preload, decreased contractility and increased afterload 3 - preload reduced with compensatory increase in afterload 4 - afterload reduction due to vasodilation and increased HR

Answer 44

2 - increased preload, decreased contractility and increased afterload - myocardial injury

Question 45

What is spinal shock? 1 - afterload reduction and possible bradycardia 2 - increased preload, decreased contractility and increased afterload 3 - preload reduced with compensatory increase in afterload 4 - afterload reduction due to vasodilation and increased HR

Answer 45

1 - afterload reduction and possible bradycardia - sympathetic block

Question 46

What is obstructive shock? 1 - afterload reduction and possible bradycardia 2 - increased preload, decreased contractility and increased afterload 3 - preload reduced with compensatory increase in afterload 4 - decreased preload, distended neck veins, reduced contractility

Answer 46

4 - decreased preload, distended neck veins, reduced contractility - caused by cardiac tamponade or tension pneumothorax