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MRCS B > Critical Care/ Trauma > Flashcards

Critical Care/ Trauma Flashcards

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1
Q

How to calculate the surface area of burns

A

Wallace’s rule of 9’s:

Head = 9&
Arms = 9%
Legs = 18% total (or 9% front/back)
Thorax = 18% total (or 9% front/back)
Abdomen = 18% total (or 9% front/back)
Groin = 1%

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2
Q

Criteria for fluids in burns patients (TBSA%)

A

Adult >15%
Child >10%

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3
Q

How to calculate IV fluid requirement in burns patients

A

Parkland formula = 24hr requirement

TBSA% x 4ml x BW(kg)

50% in first 8 hrs
50% in next 16 hrs

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4
Q

What type of IV fluid to use in burns

A

Crystalloid (e.g. Hartmanns)

NOT colloid due to increased Vascular permeability –> oncotic effect –> 3rd space losses increased

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5
Q

How to assess depth of burn

A

1st degree (superficial) = epidermis only, no blisters/ scars

2nd degree (partial thickness) = epidermis + dermis
- pain (sensate), blisters, scars
- white/ red

3rd degree (full thickness) = full dermis/ submit tissue
-insensate
-blisters/ scars
- white/ charred

4th degree = into muscle/ bone

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6
Q

Management of burns by classification (surgery vs cons)

A

1st - cons
2nd - cons for superficial, surgery for deep
3rd/4th - need grafting

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7
Q

Complications of burns

A

Hypovolemic shock
ARDS
Sepsis
Constricting burns/ compartment syndrome
Electrolyte disturbance
Renal failure (myoglobinemia)
Coagulopathy (DIC)

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8
Q

Define ARDS

A

Acute diffuse inflammatory lung injury

Characterised by:
1. Hypoxia
2. Decreased lung compliance
3. Diffuse pulmonary infiltrates on CXR
4. Normal PAWP <18 (indicating that lung fluid NOT due to left heart - PAWP increased in LVF)
5. Low PaO2/FiO2 ratio (or <26.6)

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9
Q

Pathophysiology of ARDS (2 phases)

A

1 = acute

  • Destruction of capillary endothelium, fluid leakage and interstitial oedema.
  • Inflammation due to influx of neutrophils and cytokines.
  • Alveolar BM damage -> fluid leakage into alveoli -> VQ mismatch

2 = later, reparative phase

  • organisation and fibroproliferation leading to either resolution or scarring
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10
Q

List some causes of ARDS

A

-Sepsis
-Pulmonary infections
-Gastric aspiraition
-Mechanical trauma/ contusion

-Hypersensitivity reaction
-Inhaled irritants
-Burns, radiation, drowning
-Pancreatitis
-Chemical injury from drugs e.g. heroin
-Cardiopulm bypass
-Haematology - DIC/ TRALI

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11
Q

How to categorise ARDS

A

Berlin criteria based on PaO2/FiO2 ratio

Mild 200-300
Mod 100-200
Severe <100

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12
Q

Management of ARDS

A

A) Admit to ICU
B) Treat underlying cause
C) Supportive therapy:

  1. Ventilation
    - PEEP - to prevent closure of alveoli (5-15cm H20)
    -Proning
  2. Steroids
  3. Fluids
    - replace but don’t overload. May want to measure PAWP with Swan Ganz catheter
  4. Other support - VTEP, nutrition
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13
Q

Long term sequelae of ARDS

A

Impaired gas exchange
Decreased compliance - lungs stiff/ scarred
Pulmonary HTN

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14
Q

Define PIP and PEEP

A

PIP (MEASURE) = peak inspiratory pressure aka maximum pressure in airways reached during inspiration
- may be increased in blockage, larger tidal vol, low lung compliance (e.g. ARDS)
- monitored to avoid lung injury

PEEP (GIVEN) = positive end expiratory pressure aka at end of exhalation to keep alveoli open/ prevent collapse (atelectasis)
- crucial in ARDS

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15
Q

How to calculate cerebral perfusion pressure

A

CPP = MAP - ICP

MAP = DBP + 1/3 (SBP-DBP)

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16
Q

What is the MAP auto regulation range for maintaining a constant CPP

A

50-150 mmhg

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17
Q

Explain the physiology of raised ICP in regards to theMuno Kellie doctrine

A

Skull is a fixed box of 3 components - blood, CSF and brain (80%)

Increase in 1 component means another may decrease in compensation TO AN EXTENT

At ICP of >25, small increases -> rapid ICP rise due to poor compliance -> herniation/ coning (decompensation)

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18
Q

What is the danger of lumbar puncture in raised ICP?

A

Herniation/ coning

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19
Q

Features of an extradural heamatoma:
a) cause
b) presentation
b) CT

A

a) cause = temporal injury -> rupture of middle meningeal artery
b) presentation = lucid interval, may have raised ICP/ risk of coning
b) CT = convex

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20
Q

HIGH risk criteria in head injury for CT brain

A

High:
Anticoagulated
>65
Base of skull # signs
Suspected open/ depressed skull #
GCS <15 at 2 hrs post injury
>2 episodes vomiting

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21
Q

MEDIUM risk criteria in head injury for CT brain

A

Retrograde amnesia >30 mins
Dangerous mechanism

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22
Q

What is a normal ICP value?

A

Supine: 7-15mmhg
Standing: -10mmhg

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23
Q

What is the gold standard of measuring ICP?

A

Intraventricular catheter (into skull, into ventricles)
- most invasive but most accurate

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24
Q

List some other methods of measuring ICP

A

Intraparenchymal probe
Epidural probe
Subarachnoid probe

Lumbar CSF (contraindricated)
Tympanic membrane displacement
Transcranial doppler

These are less accurate than IV catheter

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25
What is the Cushing's reflex/ triad in raised ICP?
Hypertension and bradycardia + respiratory abnormalities Life threatening physiological response to raised ICP
26
How/ why does the Cushing's reflex occur?
Sympathetic response to raised ICP. HTN: Symp NS triggered and causes rise in BP to overcome reduced blood to brain 2y to raised ICP Bradycardia: HTN stimulates baroreceptors -> p'symp reflexive decrease in HR Abnormal breathing: as a sign of brain herniation/ brainstem compression
27
In head injury, what would unilateral contraction of pupil + normal light reflex mean?
Sympathetic disruption
28
In head injury, what would bilateral dilation of pupil + slow light reflex mean?
CNS hypoperfusion (or bilat 3rd CN palsy)
29
In head injury, what would unilateral dilation of pupil + slow light reflex mean?
3rd CN palsy / herniation/ PCOM aneurysm
30
In head injury, what would RAPD + normal consensual light reflex mean?
Injury to optic nerve (2nd CN)
31
What is a secondary brain injury?
Exacerbation of initial injury by: Odesa, hypoxia, infection, haemorrhage, herniation etc
32
Management of raised ICP in head injury
Drugs - reduce cerebral oedema - IV mannitol (osmotic diuretic) 0.5-1g/kg (5-10mls 10%) - Furosemide (loop diuretic) 0.5-1g/kg - Maintain serum Na Improve venous drainage - positional Reduce cerebral metabolism - temp regulation, sedation Decompressive craniotomy
33
When should ICP be monitored
If GCS 3-8 Mandatory if abnormal CT, advised if normal CT
34
What is the difference between a medical and surgical 3rd CN palsy
Medical - eye down + out (usually due to DM/ HTN etc) Surgical - usually due to SOL/ compression and affects p'sump fibres running with 3rd nerve - causes ptosis/ dilatation
35
Indications for intubation in head injury
GCS Risk of raised ICP)
36
Management of acute subdural haematoma?
Urgent evacuation if - coma/ reduced GCS/ ICP rise - over 10mm clot thickness - midline shift >5mm + chance of recovery Non surgical: ICU, ICP monitoring and serial CT, evacuate if deterioration
37
Alternative to intubation for managing airway/ ventialtion
Tracheostomy Advantages = Help with cleaning face/ mouth, easier weaning, less likely to aspirate
38
Position of needle decompression in tension pneumothorax?
4th/5th intercostal space, mid axillary line ABOVE rib Then chest tube
39
Shock classification by blood volume loss
1) <750ml/ 15% 2) 750-1500ml/ 15-30% 3) 1500- 2000ml/ 30-40% 4) >2000ml/ 40%
40
Shock classification by observations/ urine output
1) all normal 2) BP NORMAL, HR >100, RR 20-30, UO 20-30 3) BP low, HR >120, RR 30-40, UO 5-15 4) BP low, HR >140, RR >40, UO <5
41
Areas examined on fast scan for free fluid
1 - perihepatic space (Morison's pouch/ hepatorenal recess) 2- perisplenic space 3 - pericardium 4 - pelvis
42
what are reasons for a chest tube not swinging?
improper placement (not in pleural cavity) Blockage
43
What is the mechanism of spinal shock vs neurogenic shock
Spinal - peripheral neurone below SCI level become temporarily unresponsive to brain stimuli Neurogenic - disruption of sympathetic pathways causing vasodilation
44
What agents can be given in neurogenic shock?
Vasopressors Adrenaline/ noradrenaline/ dopamine
45
Clinical assessment of 1 - corticospinal tract 2 - spinothalamic tract 3 - dorsal column tract
1 - voluntary muscle movement/ response to painful stimuli 2 - pinprick 3 - proprioception (finger/ toe position) + vibration
46
Characteristics of brown sequard syndrome
Loss of ipsilateral motor/ sensory + proprioception Loss of contralateral pain/temp
47
Characteristics + cause of anterior cord syndrome
Usually ischaemic Maintained dorsal columns (vibration/ conscious proprioception) Loss of bilateral motor/ sensory/ pain and temp
48
Characteristics + cause of central cord syndrome
Hyperextension injury in pt with cervical canal stenosis UL weakness > LL weakness Varied sensation
49
How to confirm urethral injury in pelvic #
Cystourethrogram (antegrade/ retrograde)
50
Contraindications to catheterisation
Blood at meatus/ urethral trauma Perineal haematoma High riding prostate Pelvic fracture Pre-existing infection at glans Stenosis
51
Management of pelvic fractures
ASAP: 1) Pelvic binder 2) IV TXA 3) CT If active bleeding/ unstable: - Surgical packing/ IR embolisation Vertical shear - traction Assess for urethral/ bladder injury
52
Normal compartment pressures
0-15mmhg >30 = indication for fasciotomy
53
How does compartment syndrome/ rhabdo cause renal failure?
Myoglobulin = o2 binding protein in muscles, nephrotoxic. Causes direct injury to renal tubules - collects, causing obstruction and ischemia/ damage. Also causes oxidative stress to renal cells. Acid base disturbance from release of electrolytes from muscle ->metabolic acidosis -> exacerbate renal dysfunction
54
Indications for management in specialist burns unit
TBSA: >5% children, 10% adults Age: <5 or >60 Type: high pressure steam, electricity, chemicals Location: hands, feet, face, circumferential, perineum, flexures Inhalation injury Serious comorbidity NAI suspected
55
What is the Mount Vernon formula for burns fluids
( %TBSA burns x wt(kg) ) /divided by 2 Over 36hrs - 4,4,4,6,6,12
56
Criteria for confirming brainstem death/ areflexia and who
1) Irreversible brain damage (reversible causes excluded) 2) Known aetiology (e.g. CT head showing head injury) Who: 2 doctors on separate occasions -1 must be ITU/ equivalent consultant -Both GMC reg >5yrs -Neither involved in transplant team/ pts for transplant
57
Examination criteria for brainstem death
Pupil reflex - fixed unresponsive (CN 2/3) Corneal reflex (pons, CN 5/7) Oculi-vestibular reflex (pons, CN 3/4/6/8) Supraorbital pressure Cough/gag reflex (medulla, CN 9/10)
58
What's the apnoea test
After brainstem areflexia confirmed HOW: Pre-oxygenate, Then hypoventilate (ABG = ph <7.40 + PaCO2 >6) Disconnect ventilator, observe 5 mins, recheck ABG (+ve if >0.5 PaCO2 rise)
59
Absolute contraindications for organ donation
CJD and HIV
60
Relative contraindications for organ donation
Cancer other BBVs Age Multi-organ failure Extended hypoxia
61
Definition of compartment syndrome
Elevated interstitial pressure in a closed osteofascial compartment resulting in restriction of capillary/ microvascular blood flow
62
How to perform a fasciotomy
Mark, consent and prep Prep + drape 2 longitudinal incisions: 1) ant/lat to access ant + lat compartments - 2 fingers lateral to tibia - just above ankle -> lvl of tib tuberosity 2) ant/med to access posterior compartments - 2 fingers medial to tibia - 5cm above med mal -> lvl of tib tuberosity Divide underlying fascia Debride any necrotic tissue Do not close wound - can leave mesh, close once swelling down
63
Definition of rhabdomyolysis
Release of muscle cell components into systemic circulation which can be toxic.
64
Causes of rhabdomyolysis
Trauma - # or crush Burns, Ischaemia + reperfusion Excess exercise/ seizures Drugs/ toxins/infection Hypo/hyperthermia Hereditary (rare) e.g DMD
65
CK value to dx rhabdo
5x normal value
66
Complications of rhabdomyolysis
AKI/ renal failure (nephrotoxic effects of myoglobulin -> ATN) Electrolyte disturbance - high K with metabolic acidosis - low Ca, high PO4/urate/ lactate DIC (rare)
67
Effects of rhabdo on urine
Dark/ +ve blood dipstick due to presence of myoglobulin
68
What is the most common level of cervical fracture?
C5
69
After CT, what other investigation should be considered in C-spine injury?
CT angio of the neck to asses for carotid/ vertebral artery injuries
70
What is the bulbocavernosus reflex? What is its significance in spinal trauma
Anal spinster contraction after tugging on foley or squeezing/ applying pressure to glans/ clitoris Significance = absence in context of spinal trauma often means spinal shock. One of 1st reflexes to return
71
How does autonomic dysreflexia happen?
In SCI above T6 level. Insult/ injury below injury level (e.g. AUR/ infection) causes sympathetic response --> vasoconstriction + HTN. The brain cannot send p'sump signals to counteract this due to SCI, therefore there is only p'symp response above injury level --> bradycardia + vasodilation (-> blurred vision/ headache)
72
Symptoms of autonomic dysreflelxia
Sudden HTN Bradycardia Flushing/ sweating above level of SCI Blurred vision/ headache Cold below level of injury Life threatening: CVA Seizures Arrhythmia/ arrest Pulmonary oedema
73
How to manage autonomic dysreflexia episode
Sit upright (lower BP) Identify trigger- bladder/ bowels/ tight clothing/ skin issues Medication if ongoing - nifedipine, labetalol
74
Complete vs incomplete spinal cord injury
Differentiated by the presence/ absence of some remaining sensory/ motor function below level of injury
75
Clinical measures to prevent secondary brain injury
RSI to sedate and control ventilation - keep PaO2 >13 and PaCO2 <5.3 (hyperventilate) - to decrease CPP and lessen oedema 45 degrees Insert central line/ intraventricular pressure monitor Optimise BP/ fluids/ temperature/ oxygenation/pressors etc
76
What is cerebral perfusion pressure
Difference between MAP and ICP, driving o2 delivery to brain
77
What is a normal MAP, CPP, ICP
MAP: >90 CPP: >65 ICP: 7-15 (<25)
78
How is cerebral blood flow auto regulated?
1) Myogenic - vasodilation/constriction in response to BP (from SBP of 50-150) 2) Metabolic - increased activity in specific area requiring increased blood flow. Low PaO2 or high PaCO2/H+ -> local vasodilation
79
What % of cardiac output goes to brain?
10-15%
80
Causes of hydrocephalus
Increased production - choroid plexus carcinoma Decreased re-absorption - sinus thrombus, hameorrhage Decreased circulation - tumour, haemorrhage, oedema, abscess, aqueduct stenosis
81
Production/ circulation of CSF
Produced in choroid plexus in ventricles Lateral -> foramen of monroe - >3rd -> aqueduct of Sylvius -> 4th -> spinal cord Passes into subarachnoid space via foramen of Luschka + Magendie and reabsorbed
82
Plasma vs CSF differences
CSF: LOWER glucose, pH, protein, cholesterol HIGHER chloride
83
Steps of controlling arterial bleeding from open trauma wound (e.g. open #)
1 - direct pressure 2 - pressure dressing 3 - compress proximal artery 4 - tourniquet
84
According to ATLS - what abx for open #?
Cefalosporin + gent/ cipro
85
Why should traction splint be avoided in pt with same side femur + tib/fib #s?
Can cause neurovascular injury
86
What is a chance fracture/ causes of
Lumbar vertebral # - transverse through body Caused by rapid flexion over fixed axis anterior to vertebral column e.g. lap seatbelt
87
Most common part of CT fractured
Odontoid peg
88
Most common level of c spine # or subluxation
#= C5 Sublux = C5 on C6 (as greatest area of flexion = C5/6)
89
Indications on C-spine trauma for CT angio/ screening for vertbral or carotid a. injury
C1-3 # Any C # with subluxation # involving transverse foramen
90
In paeds trauma vs adults - what A-E issue are they much more at risk of
Hypoxia/ hypoventilation and apnea Also hypothermia due to ratio of surface area: body mass Bone #s less likely but do not sure out underlying organ injury
91
How to estimate paeds wt in trauma
Wt (est kg) = (age x2) +10
92
Common causes of deterioration in intubated patients
DOPE: Dislodged Obstruction Pneumothorax (tension) Equipment failure
93
Urine output goals in paeds
Infant: 1-2ml/kg/hr Child:1-1.5 Teens: 0.5

MRCS B (10 decks)

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