Emergency medicine

Question 1

What is normal pH on a blood gas?

Answer 1

7.35 to 7.45

Question 2

What is normal PaCO2 on a blood gas?

Answer 2

4.7 - 6 kPa

Question 3

What is normal PaO2 on a blood gas?

Answer 3

11-13 kPa

Question 4

What is a normal HCO3- on a blood gas?

Answer 4

22-26 mEq/L

Question 5

What is a normal base excess on blood gas?

Answer 5

-2 to +2 mol/L

Question 6

How to see if the patient is hypoxic on the blood gas

Answer 6

PaO2 should be >10 on room air

If they’re having oxygen therapy - their PaO2 should be 10kPa less than the % inspired concentration FiO2

Question 7

What percentage oxygen is delivered by nasal cannulae, simple face masks, non-rebreather mask and venturi masks?

Answer 7

Nasal cannulae -
1L - 24%
2L - 28%
3L - 32%
4L - 36%

simple face mask - 40-60%

Non-rebreather mask - 60-90%

venturi masks -
24%
28%
35%
40%
60%

Question 8

What are the two types of respiratory failure?

Answer 8

Type 1 respiratory failure = hypoxaemia with normocapnia

Type 2 respiratory failure = hypoxaemia with hypercapnia

Question 9

Causes of type 1 respiratory failure

Answer 9

Pulmonary oedema
Bronchoconstriction
Pulmonary embolism

Question 10

Causes of type 2 respiratory failure

Answer 10

COPD
pneumonia
rib fractures
obesity
Guillain Barre
MND
Opiates

Question 11

What are the 4 acid base disturbances you see on blood gas?

Answer 11

Respiratory acidosis - acidotic pH <7.35, with high PaCO2 & normal HCO3-

Respiratory alkalosis - alkalemic pH >7.45, with PaCO2 low & normal HCO3-

Metabolic acidosis - acidotic pH <7.35, with normal PaCO2 & low HCO3-

Metabolic alkalosis - alkalemic pH >7.45, with PaCO2 normal & high HCO3-

Question 12

How can you tell if an acid base abnormality has been compensated for on blood gas?

Answer 12

Respiratory acidosis with metabolic compensation - low/normal pH, with high PaCO2 and high HCO3-

Respiratory alkalosis with metabolic compensation - high/normal pH, with low PaCO2 and low HCO3-

Metabolic acidosis with respiratory compensation - low pH, with low HCO3- and low PaCO2

Metabolic alkalosis with respiratory compensation - high pH, with high HCO3- and high PaCO2

Question 13

What does base excess show on a blood gas?

Answer 13

shows metabolic acidosis or alkalosis

• High BE = there is a higher than normal amount of HCO3- in the blood (due to metabolic alkalosis or compensated respiratory acidosis)
• Low BE = there is a lower than normal amount of HCO3- in the blood (metabolic acidosis or compensated respiratory alkalosis)

Question 14

How can you tell if there’s mixed acidosis and alkalosis?

Answer 14

the CO2 and HCO3– will be moving in opposite directions (e.g. ↑ CO2 ↓ HCO3– in mixed respiratory and metabolic acidosis).

Question 15

Causes of respiratory acidosis

Answer 15

Respiratory depression - opiates
Guillian-Barre
Asthma
COPD

Question 16

Causes of respiratory alkalosis

Answer 16

Anxiety - panic attack
pain causing an increase RR
Hypoxia causing increased alveolar ventilation to try compensate
PE
Pneumothorax

Question 17

How do you calculate the anion gap?

Answer 17

Cations - anions

e.g. Na - (Cl + HCO3-)

Question 18

What is a normal anion gap?

Answer 18

8-12

Question 19

What is an abnormal anion gap?

Answer 19

> 20

Shows anion gap acidosis

Question 20

Causes of high anion gap metabolic acidosis

Answer 20

DKA
Lactic acidosis
Aspirin overdose
Renal failure

Question 21

causes of normal anion gap metabolic acidosis

Answer 21

GI loss of HCO3- = diarrhoea, ileostomy, proximal colostomy
Renal tubular disease
Addison’s disease (primary adrenal insufficiency)

Question 22

causes of metabolic alkalosis

Answer 22

GI loss of H+ ions - vomiting and diarrhoea
Renal loss of H+ ions - loop and thiazide diuretics, HF, nephrotic syndrome, cirrhosis, Conn’s syndrome (primary hyperaldosteronism)

Question 23

Causes of mixed respiratory and metabolic acidosis

Answer 23

Cardiac arrest

Multi-organ failure

Question 24

causes of mixed respiratory and metabolic alkalosis

Answer 24

Liver cirrhosis in addition to diuretic use
Hyperemesis gravidarum
Excessive ventilation in COPD

Question 25

Mx of acute bronchitis

Answer 25

Antipyretic SABA ABx if bacterial cause suspected - unlikely as mostly caused by viruses

Question 26

Mx for all patients with ACS

Answer 26

Aspirin 300mg Oxygen if sats <94% Morphine if severe pain Nitrates (careful if hypotensive)

Question 27

Mx for STEMI

Answer 27

Aspirin 300mg Oxygen if sats <94% Morphine if severe pain Nitrates (careful if hypotensive) PCI if possible within 120 minutes - give praugrel, unfractionated heparin If PCI not possible within 2 hours = fibrinolysis (streptokinase, alteplase and tenecteplase) and give ticagrelor afterwards

Question 28

Mx for NSTEMI

Answer 28

Aspirin 300mg Fondaparineux if no immediate PCI is planned Estimate 6 month mortality (GRACE) If low risk = ticagrelor High risk = PCI, give ticagrelor & unfractionated heparin

Question 29

Criteria for diagnosing AKI

Answer 29

Rise in creatinine of 26 + in 48 hours >50% rise in creatinine over 7 days Fall in urine output to less than 0.5ml/kg/hour for more than 6 hours >25% fall in eGFR in children/young adults in 7 days

Question 30

Mx of AKI

Answer 30

IV fluids if dehydrated Stop NSAIDs, ahminoglycosides, ACei, ARBs, diuretics Consider if the person has sepsis and treat it

Question 31

Symptoms of anaphylaxis

Answer 31

Swelling of throat/tongue - hoarse voice and stridor Respiratory wheeze Dyspnoea Hypotension Tachycardia Must be having ABC problems to have anaphylaxis Other symptoms - generalised pruritus, widespread erythematous/urticarial rash

Question 32

Mx of anaphylaxis

Answer 32

IM adrenaline - 0.5ml 1 in 1000 for adults (>12yo) give IM adrenaline every 5 minutes if necessary IV fluids for shock IV adrenaline infusion if still ABC problems despite 2 doses of IM adrenaline After stabilisation: - Chlorphenamine - Serum trypase levels Give an adrenalin auto-injector on discharge

Question 33

mx for ruptured AAA

Answer 33

symptoms - severe central abdo pain radiating to the back with pulsatile expansile mass +/- shock immediate vascular review CT if haemodynamically stable to confirm diagnosis, if not straight to theatre

Question 34

mx for acute heart failure

Answer 34

IV loop diuretic - furosemide oxygen Vasodilators - nitrates (unless hypotensive) If respiratory failure = CPAP If hypotension - inotropic agent (dobutamine), vasopressor (norepinephrine), mechanical circulatory assistance (intra-aortic balloon counter pulsation/ventricular assist device) Continue their beta blockers

Question 35

Mx for acute exacerbation of COPD

Answer 35

Increase frequency of bronchodilator / give neb SABA Prednisolone 30mg (for 5 days) ABx - amoxicillin or clarithromycin or doxycycline

Question 36

mx of compartment syndrome

Answer 36

fasciotomy raise limb remove bandages/casts

Question 37

mx of DVT

Answer 37

apixaban/rivaroxaban at treatment dose unless renal impairment / antiphospholipid syndrome = LMWH Stop after 3 months if provoked DVT or after 6 months if unprovoked

Question 38

Mx of DKA

Answer 38

Fluid replacement with 0.9% NaCl Insulin IV fixed rate 0.1 unit/kg/hour Once glucose is <15 mol/L, start 5% IV dextrose Correct hypokalaemia that results from insulin infusion - replace at a rate of <20 mol/hour

Question 39

Mx of ectopic pregnancy

Answer 39

+ve pregnancy test + transvaginal USS Expectant, medical or surgical management depending on size of ectopic, ruptured, symptoms, presence of fetal heartbeat, level of HCG

Question 40

Mx of status epilepticus

Answer 40

ABC IV lorazepam, PR diazepam or buccal midazolam Repeat after 10-20 minutes Ongoing = IV phenytoin or phenobarbital infusion Ongoing = GA and intubation

Question 41

Characteristics of extra dural haemorrhages

Answer 41

Between skull bone and dura mater Rupture of middle meningeal artery on the temporal surface of the skill Hx of trauma and skull fracture Lucid interval followed by unconsciousness CT = convex shaped mass

Question 42

Mx of extra dural haemorrhage

Answer 42

ABCDE approach Check BMs Check for coagulopathy and reverse any anticoagulation prophylactic abx for open skull fractures anticonvulsants to reduce seizure risk Mannitol/barbiturates to reduce ICP Burr hole craniotomy - to remove haematoma Hemicraniotomy if lots of blood/cerebral oedema