Emergency medicine Flashcards
What is normal pH on a blood gas?
7.35 to 7.45
What is normal PaCO2 on a blood gas?
4.7 - 6 kPa
What is normal PaO2 on a blood gas?
11-13 kPa
What is a normal HCO3- on a blood gas?
22-26 mEq/L
What is a normal base excess on blood gas?
-2 to +2 mol/L
How to see if the patient is hypoxic on the blood gas
PaO2 should be >10 on room air
If they’re having oxygen therapy - their PaO2 should be 10kPa less than the % inspired concentration FiO2
What percentage oxygen is delivered by nasal cannulae, simple face masks, non-rebreather mask and venturi masks?
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%
What are the two types of respiratory failure?
Type 1 respiratory failure = hypoxaemia with normocapnia
Type 2 respiratory failure = hypoxaemia with hypercapnia
Causes of type 1 respiratory failure
Pulmonary oedema
Bronchoconstriction
Pulmonary embolism
Causes of type 2 respiratory failure
COPD pneumonia rib fractures obesity Guillain Barre MND Opiates
What are the 4 acid base disturbances you see on blood gas?
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-
How can you tell if an acid base abnormality has been compensated for on blood gas?
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
What does base excess show on a blood gas?
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)
How can you tell if there’s mixed acidosis and alkalosis?
the CO2 and HCO3– will be moving in opposite directions (e.g. ↑ CO2 ↓ HCO3– in mixed respiratory and metabolic acidosis).
Causes of respiratory acidosis
Respiratory depression - opiates
Guillian-Barre
Asthma
COPD
Causes of respiratory alkalosis
Anxiety - panic attack pain causing an increase RR Hypoxia causing increased alveolar ventilation to try compensate PE Pneumothorax
How do you calculate the anion gap?
Cations - anions
e.g. Na - (Cl + HCO3-)
What is a normal anion gap?
8-12
What is an abnormal anion gap?
> 20
Shows anion gap acidosis
Causes of high anion gap metabolic acidosis
DKA
Lactic acidosis
Aspirin overdose
Renal failure
causes of normal anion gap metabolic acidosis
GI loss of HCO3- = diarrhoea, ileostomy, proximal colostomy
Renal tubular disease
Addison’s disease (primary adrenal insufficiency)
causes of metabolic alkalosis
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)
Causes of mixed respiratory and metabolic acidosis
Cardiac arrest
Multi-organ failure
causes of mixed respiratory and metabolic alkalosis
Liver cirrhosis in addition to diuretic use
Hyperemesis gravidarum
Excessive ventilation in COPD
Mx of acute bronchitis
Antipyretic
SABA
ABx if bacterial cause suspected - unlikely as mostly caused by viruses
Mx for all patients with ACS
Aspirin 300mg
Oxygen if sats <94%
Morphine if severe pain
Nitrates (careful if hypotensive)
Mx for STEMI
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
Mx for NSTEMI
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
Criteria for diagnosing AKI
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
Mx of AKI
IV fluids if dehydrated
Stop NSAIDs, ahminoglycosides, ACei, ARBs, diuretics
Consider if the person has sepsis and treat it
Symptoms of anaphylaxis
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
Mx of anaphylaxis
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
mx for ruptured AAA
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
mx for acute heart failure
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
Mx for acute exacerbation of COPD
Increase frequency of bronchodilator / give neb SABA
Prednisolone 30mg (for 5 days)
ABx - amoxicillin or clarithromycin or doxycycline
mx of compartment syndrome
fasciotomy
raise limb
remove bandages/casts
mx of DVT
apixaban/rivaroxaban at treatment dose
unless renal impairment / antiphospholipid syndrome = LMWH
Stop after 3 months if provoked DVT or after 6 months if unprovoked
Mx of DKA
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
Mx of ectopic pregnancy
+ve pregnancy test + transvaginal USS
Expectant, medical or surgical management depending on size of ectopic, ruptured, symptoms, presence of fetal heartbeat, level of HCG
Mx of status epilepticus
ABC
IV lorazepam, PR diazepam or buccal midazolam
Repeat after 10-20 minutes
Ongoing = IV phenytoin or phenobarbital infusion
Ongoing = GA and intubation
Characteristics of extra dural haemorrhages
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
Mx of extra dural haemorrhage
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
