Random FFICM Questions Flashcards
What causes a high mixed venous oxygen saturation (SvO2)?
↑ SvO2
• ↑ O2 delivery, e.g.
↑ FiO2, hyperbaric O2
• ↓ O2 extraction,
e.g. hypothermia, general anaesthetic, neuromuscular blockade
• ↑ Flow states, e.g. sepsis, thyrotoxicosis, severe liver disease
What causes a low mixed venous oxygen saturation (SvO2)?
↓ SvO2
• ↓ O2 delivery, e.g. shock states, hypoxemia, anaemia
• ↑ O2 extraction, e.g. hyperthermia, shivering, pain, seizures
What is a mixed venous oxygen saturation (SvO2)?
SvO2 is obtained from a pulmonary artery catheter. It measures the end result of O2 consumption and delivery, and contains blood from both the SVC and IVC. The normal range is approximately 65–70%.
What is ScvO2?
ScvO2 measures oxygen saturation in the SVC, taken from an internal jugular, subclavian or axillary vein catheter and is sometimes used as a surrogate for SvO2.
What is the relationship between SvO2 and ScvO2?
Typically, in healthy individuals, SvO2 > ScvO2 because the brain (SVC-drained) has a higher oxygen demand compared to organs like the kidneys (IVC-drained) with lower oxygen demands.
ScvO2 can surpass SvO2 in cases where the brain’s metabolic requirement decreases, such as during anaesthesia, in TBI, or in shock, when body oxygen extraction increases, which leads to reduced oxygen saturation in the IVC.
What is functional residual capacity (FRC)?
• FRC = expiratory reserve volume + residual volume.
• It is the volume of air in the lungs after normal expiration, measured by either gas dilution or body plethysmography.
What factors affect functional residual capacity (FRC)?
↑ FRC :
• Standing position
• Asthma/COPD
• PEEP/CPAP
↓ FRC
• Supine position
• Obesity
• Pregnancy
• Restrictive lung disorders
• General anaesthesia
What should be the normal cuff pressure of a tracheostomy and how often should it be checked and why?
20–30 cm H2O
It should be checked every 8–12 hours, (or more frequently depending on the clinical picture)
Higher cuff pressures may compress tracheal capillaries, limit blood flow, and predispose to tracheal necrosis (ischaemic damage).
What is the difference between cardiac output and cardiac index and what are their normal values?
• Cardiac Output = Heart Rate × Stroke Volume
Normal range ~ 4–8 L/min
• Cardiac Index = Cardiac Output/Body
Surface Area
Normal range ~ 2.5–4 L/min
What is the physiological role of C‐reactive protein?
• A pentraxin protein synthesised in the liver
• ↑ In response to inflammation
• Binds to phosphocholine on the surface of dead/dying cells, which activates the complement system
Which cardiac structural abnormality may the presence of a right bundle branch block in a young adult indicate?
Atrial septal defect
What are some of the causes of a raised MCV?
DRAMATIC
D - Drugs, e.g. anticonvulsants, antimicrobials, chemotherapy
R - Reticulocytosis
A - Alcohol abuse
M - Megaloblastic anaemia, e.g. pernicious anaemia, B12/folate deficiency
A- Artefact, e.g. aplasia, myelofibrosis, hyperglycaemia, cold agglutinins
T - Thyroid (hypothyroidism)
I - Immature bone marrow cells, e.g. myelodysplastic syndrome
C - Chronic liver disease
What is the dose of IV salbutamol in treating life‐threatening asthma, and what are some side effects?
• Dose: 3–20 mcg/min
• Side effects: tachycardia, arrhythmias,
tremors, hyperglycaemia, hypokalaemia, and type B lactic acidosis
What are the mechanisms of drug‐induced hyperkalaemia?
K+ supplements
• Sando-K
• IV fluids with K+
Drugs that impair K+ distribution
• Beta blockers
• Arginine
• Digoxin
• Suxamethonium
Drugs that ↓ renal K+ excretion
• Calcineurin inhibitors, e.g. tacrolimus and ciclosporin
• Potassium-sparing diuretics,
e.g. spironolactone,
eplerenone
• Some antibiotics, e.g.
trimethoprim
Drugs that impact on the RAAS
• NSAIDs
• ACE inhibitors, ARBs
• Heparin
When do you control hypertension in the first 24 hours after an acute ischaemic stroke according to NICE?
NICE advises against actively managing hypertension during this period, except in the following situations:
• To facilitate thrombolysis–target BP < 185/110.
• In cases of pre-eclampsia, aortic dissection, or hypertensive encephalopathy/nephropathy/cardiac failure.
What percentage TBSA burn would meet the criteria for referral to a burns centre on area alone?
> 40% Total Body Surface Area (TBSA)
Where is propofol predominantly metabolised?
Liver: Hepatic metabolism, primarily via glucuronidation and sulfation pathways.
What is the dose of IV magnesium in the management of acute asthma, and how does it work as a bronchodilator?
Dose:
1.2–2 g IV over 20 minutes
Mechanism as a bronchodilator:
1. Calcium blocker in bronchial smooth muscle
2. ↓ Ach release at the NMJ
3. ↑ Sensitivity of β-receptors to catecholamines
What is the Parkland formula for IV fluid replacement after a burn, and does it take into account pre-hospital fluid administration?
4 mL/kg/%TBSA over 24 hours
Half of total is given in the first 8 hours after the injury.
When calculating TBSA, erythematous regions are omitted unless there is additional blistering or underlying evidence of a partial- thickness burn.
This formula takes into account pre- hospital fluid administration. Therefore, any prehospital fluid is subtracted from total.
Aiming for 0.5ml/kg/hour urine output
What did the PROPPR trial (2015) demonstrate for blood product administration in a 1:1:1 ratio compared to a 1:1:2 plasma:platelet:red
cell ratio in patients with severe trauma and major bleeding?
• No difference in all-cause 24-hour or 90-day mortality
• Post-hoc analysis found a significant reduction in death by exsanguination within the first 24 hours and a higher rate of achieving haemostasis in the 1:1:1 group compared to the 1:1:2 group.
What are the 12 physiological variables of the APACHE II score, how do you calculate the score and what does it mean?
CNS:
GCS
CVS:
MAP
HR
Resp:
RR
PaO2
Renal:
Arterial pH
Na+
K+
Creatinine
Micro/Haem:
Temperature
WCC
Hct
The worst of these variables within the first 24 hours of critical care admission is used
Effects of age and chronic health are incorporated to give a single score with a maximum of 71. A score of >25 represents a predicted mortality of >50%.
What dose of adrenaline do you give in adult anaphylaxis?
IM: 0.5–1mL of 1:1,000 (0.5–1mg)
OR
IV: 0.5–1mL of 1:10,000 (50–100 mcg)
What is the difference between intra‐ abdominal hypertension (IAH) and abdominal compartment syndrome (ACS), and how do you measure intra-abdominal pressure (IAP)?
• IAH: sustained or repeated pathological elevation of IAP ≥ 12 mmHg
• ACS: sustained IAP > 20 mmHg + new organ dysfunction/failure +/− abdominal perfusion pressure (APP) < 60 mmHg
IAP is measured:
• Direct: puncture of the abdominal cavity
• Indirect: via a urinary catheter in the bladder or a balloon-tipped catheter inserted into the stomach. Correlates well with direct measurements but can be inaccurate when there are adhesions, pelvic fractures, and abdominal packs.
Where in adults does the trachea start and divide anatomically?
• Starts at C6
• Extends to T4 where it bifurcates
• It is approximately 10–12 cm long
• The right main bronchus separates at a
25° angle and the left main bronchus separates at a 45° angle.
What is the evidence for a decompressive hemicraniectomy (DH) in malignant middle cerebral artery syndrome according to the DECIMAL (2007), HAMLET (2009) and DESTINY II (2011) trials?
• Mortality: Decompressive hemicraniectomy significantly reduces mortality compared to conservative treatment in all three studies. This benefit appears to be particularly strong when surgery is performed early (within 48 hours) after stroke onset.
This was observed in younger patients (18–55 years in DECIMAL) and older patients (≥61 years in DESTINY II), as well as in the varied population of HAMLET.
• Neurological Disability: The findings on functional outcome are more complex and are potentially dependent on factors like age, stroke severity, and time to surgery:
Decompressive hemicraniectomy did not significantly improve the proportion of patients achieving a ‘good’ functional outcome (mRS ≤ 3) at 6 or 12 months in DECIMAL and HAMLET.
However, it significantly increased the proportion of patients achieving a ‘moderate’ functional outcome (mRS ≤ 4) at six months in DECIMAL and DESTINY II.
Notably, no surviving patients in DESTINY II achieved the best possible functional outcome (mRS 0–2).
Overall: Decompressive hemicraniectomy offers a clear and substantial mortality benefit. While it may not guarantee good recovery and return to pre-stroke levels of function, it can increase the chances of achieving moderate disability as opposed to severe disability or death. This decision requires individualised assessment and MDT involvement.
How do you distinguish between moderate, severe and life-threatening acute asthma?
Moderate PEFR > 50%
No features of severe asthma
Severe PEFR 33–50%
RR ≥ 25
HR ≥ 110
Inability to complete sentences in one breath
Life‐threatening
Features of severe asthma + at least one of:
• PEFR < 33%
• SpO2<92%
• Normal or ↓ PCO2: implies poor ventilation
• Cyanosis, confusion or coma
• Hypotension or ↓ HR
• Exhaustion or poor
respiratory effort
• Silent chest
• Tachy(arrhythmia)
When is it safe to use suxamethonium after a significant burn injury?
• Within the first 24 hours after the burn
• One year after the burn
How do you calculate the internal diameter of an endotracheal tube in the paediatric population?
Cuffed : [age / 4] + 3.5
Uncuffed : [age / 4] + 3.5 + 0.5
What is the recommended therapeutic management for a variceal haemorrhage that continues to bleed despite pharmacological intervention, endoscopic banding and balloon tamponade?
Transjugular Intrahepatic Portosystemic Shunt (TIPS)
When is damage control surgery more preferable than definite surgery in trauma?
When there is severe haemorrhagic shock and/or ongoing bleeding.
This is particularly necessary if the lethal diamond is present (hypothermia, acidosis, coagulopathy and hypocalcaemia) and in patients who have inaccessible major venous injuries or those who require time-consuming procedures.
What risk is associated with the administration of suxamethonium after a spinal cord injury, and how soon after the injury does this risk occur?
• Life-threatening hyperkalaemia
• 72 hours after spinal cord injury
How is the rapid shallow breathing index (RSBI) useful as a weaning predictor?
RSBI = RR / Tv (TV in Litres not mls)
• RSBI < 105: 80% chance of successful extubation
• RSBI >105: strongly suggests weaning failure
What happens to pulmonary artery pressure after a cardiac arrest?
↑
Multifactorial reasons why this may occur include:
Post-ROSC
o ↑ PVR secondary to hypoxia/acidosis o ↑ PAP secondary to cardiac dysfunction as part of post-cardiac
arrest syndrome
Precipitant of cardiac arrest
o ↑ PAP secondary to cardiac
dysfunction (e.g. STEMI) or pulmonary embolism
What is meant by intention to treat analysis in a randomised controlled trial?
• All participants are analysed based on their originally assigned treatment groups, regardless of whether they completed or received the intended treatment.
• This approach helps maintain the randomisation and avoids biases caused by crossover or dropout.
Which clinical features in someone with a burn may indicate the need for early intubation?
• GCS<8
• Respiratory distress or failure
• Noticeable swelling or blistering in the lips, tongue or oropharynx
• Voice changes, e.g. hoarseness or stridor
• Singed nasal hair
• Carbonaceous sputum
• Extensive burns of the face or neck,
including circumferential burns
How does digoxin work in treating atrial fibrillation with a fast ventricular rate?
Direct:
Inhibits cardiac Na+/ K+-ATPase causing an
↑ Intracellular Na+ which leads to
Exchange of Na+ for Ca2+ via the Na+/Ca2+ pump causing
↑ Intracellular Ca2+ and↓ Intracellular Na+
↑ Intracellular Ca2+ causes ↑ cardiac contraction
↓ Intracellular Na+ prolongs refractory time of the bundle of His
Indirect:
↑ Acetylcholine at cardiac muscarinic receptors
Resulting in prolongation of the refractory period at the AV node and bundle of His
Which alternative drug can be used in the management of AVNRT if adenosine is contraindicated?
Verapamil 2.5–5 mg IV
Why may someone with primary hyperaldosteronism (Conn’s syndrome) develop muscle weakness and tetany?
Due to hypokalaemic metabolic alkalosis
Conn’s syndrome causes a low renin hypertension.
It is diagnosed by a ↑ aldosterone:renin ratio.
What modifications have been implemented in advanced life support algorithms for resuscitating individuals with hypothermia?
• Refrain from administering adrenaline or any other drugs until the temperature is >30°C.
• When the temperature ranges from 30°C to 35°C, double the dose intervals for ALS drugs.
• In cases of VF, consider delivering up to three shocks if needed, but hold off on further shocks until the temperature is >30°C.
What is the most likely diagnosis if someone develops hypocalcaemia and seizures two days after starting chemotherapy?
Tumour lysis syndrome (TLS) – electrolyte abnormalities can precipitate neurological dysfunction.
What are the common biochemical abnormalities seen in tumour lysis syndrome?
Common abnormalities include:
• ↓ Calcium
• ↑ Phosphate, potassium, urate, LDH,
lactate
What causes and what cancers are associated with Tumour Lysis Syndrome?
TLS is due to the sudden and large-scale death of cells following the initiation of chemotherapy. It is often associated with acute leukaemias and high-grade lymphomas, e.g. Burkitt’s.
What are the most likely causes for developing drowsiness one week after undergoing endovascular coiling for a subarachnoid haemorrhage, when a CT scan indicates no rebleeding, infarction or hydrocephalus?
• Delayed cerebral ischaemia (DCI)
o Cerebral vasospasm
o Local hypoperfusion or disordered
autoregulation
• Non-convulsive seizures
What’s the rationale for including clindamycin or linezolid alongside broad- spectrum antibiotics in the treatment of necrotising fasciitis?
For the termination of toxin production
Besides hypothermia, what are some alternative reasons for the presence of J-waves on an ECG?
Normal variant (early repolarisation)
HABIT:
Hypercalcaemia
Angina – vasospastic
Brain injury including a subarachnoid
haemorrhage
Idiopathic ventricular fibrillation
Type 1 Brugada syndrome
When would you consider placing an inferior vena cava (IVC) filter after a pulmonary embolism (PE)?
• If anticoagulation is contraindicated, e.g. the bleeding risk is very high
• If thrombosis has recurred despite adequate anticoagulation
• If temporary cessation of anticoagulation within one month is anticipated, e.g. pregnant patients within one month of the expected date of delivery
IVC filters have no long-term mortality benefit. As foreign material, they are thrombogenic (↑ incidence of DVT).
What is the utility of the LRINEC (Laboratory Risk Indicator for Necrotising Fasciitis) score?
• The LRINEC score distinguishes necrotising fasciitis from other soft tissue infections, e.g. cellulitis.
• The score incorporates CRP, WCC, Hb, sodium, creatinine and glucose.
• A LRINEC score of ≥6 could be used as a potential tool to rule in necrotising fasciitis, but a score <6 should not be used to rule out the diagnosis.
• A score ≥8 has a positive predictive value >90%.
Is it necessary to check digoxin levels during and after administering digoxin‐specific antibody fragments for digoxin toxicity?
No – the assay measures both digoxin bound to antibody fragments and free digoxin. This overestimates free levels.
What fibrinogen level may warrant administering cryoprecipitate in a trauma patient?
Fibrinogen < 1.5–2 g/L
What is the normal axis for left ventricular depolarisation in an adult, and what are the Sokolow-Lyon criteria for left ventricular hypertrophy (LVH)?
• Normal axis: −30 to +90 degrees
• LVH: If the height of the R wave in
V5/6 + the depth of the S wave in V1/2 is
≥35 mm
• The most common cause of LVH is
hypertension
What are the two pathways of coagulation?
Intrinsic Pathway (APTT): Factors 8, 9, 11, 12
Extrinsic Pathway (PT): Factors 3, 7
Joint: Factors 2, 5, 10, prothrombin, fibrinogen
Which substances are primarily responsible for crystal nephropathy in tumour lysis syndrome?
Uric acid and calcium phosphate
↑ Cell turnover →
↑ purine metabolism →
↑ serum urate↑ Cell lysis →
↑ serum phosphate which binds
to calcium
Uric acid precipitates readily in the presence of calcium phosphate, and calcium phosphate precipitates readily in the presence of uric acid.
