Seminar 12 - Traumatic Head Injury Flashcards
List the clinical features of wound infection
Signs and symptoms of infection – pain, localized swelling, redness or heat
Purulent discharge
Unexplained persistent pyrexia
Malodor from the wound
Spreading – crepitus, malaise, loss of appetite
How does the body normally deal with cells which have had their DNA damaged by UV
DNA damage is sensed by checkpoint kinases e.g. ATM and ATR
These send out signals that upregulate the expression and stability of p53
This arrests cells in the G1 phase of cell cycle and promotes either high-fidelity DNA repair or the elimination of cells that are damaged beyond repair
In DIC where are the procoagulants released from
They can be released from a variety of locations such as the placenta in obstetric complications and damaged tissues in severe trauma and burns.
Which microbiology style tests may be performed on wound infection
Organisms isolated from the aseptically obtained wound culture
Gram stain for infective organisms; staining for fungal elements
Test for antigens from the organism through ELISA
Detection of antibody response to organism in host sera
PCR to detect small amounts of microbial DNA
List the ABCDE warning signs of melanoma
Asymmetry
Border – Ragged, notched, uneven, blurred
Color – Shades of black, brown and tan (variegated)
Diameter – Usually larger than 6mm (increasing diameter)
Evolving – Has been changing; texture of mole may become hard or lumpy
List potential causes of high grade sarcoma
Genetic conditions
Radiation – emergence of radiation-induced genetic mutations that encourage neoplastic transformation
Chronic lymphedema
Environmental carcinogens – Infection-induced soft-tissue tumour is Kaposi sarcoma resulting from human herpesvirus type 8 in patients with HIV
Infection
Trauma
What is a subarachnoid haemorrhage
Extravasation of blood into the subarachnoid space (SAS).
List the microscopic features of subacute (evolving) focal ischaemic infarcts
At 48-72hrs phagocytic cells are evident. In the following 2-3weeks they will become the predominant cell
The macrophages can persist in these lesions for months to years and they become stuffed with blood or products of myelin breakdown
As early as one week after the insult reactive astrocytes and newly formed vessels can be seen at the infarcts periphery
Astrocytes at the edge of the lesion will progressively enlarge, divide and develop a network of cytoplasmic extensions as liquefaction and phagocytosis continues
List the immediate compensatory mechanisms for rising ICP
Decrease in CSF volume by moving it out of foramen magnum
Decrease in blood volume by squeezing sinuses
Non-infectious vasculitis can also cause focal ischaemic CVA - true or false
True
Polyarteritis Nodosa and other non infectious vasculitis can cause single or multiple infracts in the brain
List some examples of high grade sarcoma
Clear cell sarcoma Dermatofibrosarcoma protuberans Ewing sarcoma Extraskeletal myxoid chondrosarcoma Liposarcoma
Describe a systemic wound infection
Systemic infection from a wound affects the body as a whole, with microorganisms spreading throughout the body via the vascular or lymphatic systems.
Systemic inflammatory response, sepsis and organ dysfunction are signs of systemic infection
What consequences of SAH tend to occur in the first few days post-bleed
Increased risk of additional ischaemic injury from vasospasm affecting vessels bathed in extravasated blood
Which mutations are often seen in melanoma
Mutations that disrupt cell cycle control genes e.g. CDKN2A
Mutations that activate pro-growth signaling pathways e.g. RAS and PI3K/AKT signaling
Mutations that activate telomerase e.g. TERT
Why do people in ICU experience weakness and stiffness
Muscles weaken due to long periods of inactivity.
This happens quicker when they are on a ventilator.
Why are ICU patient’s at high risk of complications
They will already be severely unwell with most having an issue with one or more organs.
This already makes them vulnerable to complications such as infection and AKI.
List the pathological features of secondary haemorrhagic infarcts
The evolution and features of these infarcts are the same as ischemic infarcts
Blood extravasation and resorption will also be seen within them
Extensive intracerebral haematomas may be seen alongside the haemorrhagic infracts if the patient is on anticoagulants
How do the ventricles appear in communicating and non-communicating hydrocephalus
Communicating - all 4 ventricles enlarged
Non-communicating - 4th ventricle normal whilst others enlarged
4th normal as CSF can’t flow into is as well due to obstruction
What are the two main triggers of DIC
Release of procoagulants into the bloodstream and the injury of endothelial cells.
Which cancers are most associated with DIC
Acute promyelocytic leukemia
Adenocarcinomas of the lung, pancreas, colon and stomach
If a person is unable to complete a GCS test - e.g. eye opening w/ facial injuries, verbal if intubated- how do you record it
Should be recorded as NT (not testable)
Infarcts in focal ischaemic CVA can be divided into which groups
Non haemorrhagic and secondary haemorrhagic infarcts
The deficits that are caused by a focal ischemic CVA can improve over time - true or false
True
Due to resolution of local oedema and reversal of injury to the penumbra
List common symptoms of cellulitis
Involved site(s): red, hot, swollen, tender
Borders are not elevated or sharply demarcated
Regional lymphadenopathy
Malaise, chills, fever, toxicity
Which vessels are most commonly the cause of subarachnoid haemorrhage
Usually arise in arterial bifurcation in circle of Willis
What is defined as a high speed RTA
Anything over 30 mph classified as ‘high speed’.
List medical management options for raised ICP
Use diuretics (mannitol, hypertonic saline, furosemide, urea)
Barbiturate coma
Anti-epileptics
What causes the contralateral hemiparesis in extradural haematoma
Compression of cerebral peduncle
What causes the ipsilateral pupillary dilatation in extradural haematoma
The expanding haematoma causes herniation of uncus of temporal lobe which compresses the pupillary fibres of CN III
Which patients are at higher risk of bleeding in reactive gastritis
Those with respiratory failure or coagulopathy
List some infections that can cause ARDS
Sepsis Diffuse pulmonary infection Viral, mycoplasmic and pneumocystis pneumona Miliary TB Gastric aspiration
When do watershed infarcts typically occur
Usually occur if the global ischemia is due to severe hypotensive episodes
Most commonly seen in patients who have been resuscitated after cardiac arrest.
List acute complications of an ICU stay
ICU delirium DVT and PE GI ulcers and bleeds Kidney failure Liver damage Pressure ulcers
What interventions may be performed after a focal ischaemic CVA to reduce the risk of further events
If due to carotid atheromatous plaques then carotid endarterectomy will be done
If there is narrowing or occlusion of vessels then angioplasty and stenting can be performed
All patients, unless contra indicated, will be placed on either a DOAC or warfarin from 2 weeks following the event
List the potential mechanisms of death in DIC
Thrombotic complications such as ischaemia and multi-organ dysfunction
Life-threatening haemorrhage due to the consumption of clotting factors
What is bazex syndrome
Condition which leads to follicular atrophoderma, multiple basal cell carcinomas, local anhidrosis
How does a subdural haemorrhage present
Slowly evolving neurologic symptoms, often with a delay from the time of injury
Why can haemoperitoneum go unnoticed
It is bleeding into a free, internal space
May not produce symptoms until they go into hypovolemic shock
What causes kidney failure in ICU
Often caused by shock, infection or medication
What is the main cause of haemorrhage in the epidural space (extradural)
Trauma
Usually associated with temporal skull fracture in adults - disrupts the middle meningeal artery
What is the most common injury type seen in RTAs
Blunt force injuries Bruises (external) - e.g. seat belt Contusions (internal) Lacerations - includes flaying Abrasions - includes road rash
What is the most common cause of wound infection following appendix/biliary surgery
Gram-negative bacilli and anaerobes
List some of the late phase (healing) complications of SAH
Meningeal fibrosis and scarring - sometimes causes obstruction of CSF flow as well as interruption of the normal pathways of CSF resorption
Survivors also at risk of hydrocephalus
How do burns cause DIC
Major trigger is the release of procoagulants such as TF
List causes of increased central venous pressure that can lead to raised ICP
Venous sinus thrombosis
Heart failure
Obstruction of jugular veins
List possible symptoms seen in an anterior cerebral artery stroke
Disinhibition and speech perseveration Primitive reflexes Altered mental status Impaired judgement Contralateral weakness - greater in arms, Contralateral cortical sensory deficits Gait apraxia Urinary incontinence
What is the most common cause of wound infection following gastroduodenal surgery
Gram-negative bacilli and streptococci
How does a ruptured saccular aneurysms present clinically
Sudden, excruciating headache (“worst headache ever”) - due to blood at high arterial pressure entering SAS
Rapid loss of consciousness
Neck stiffness + photophobia – meningeal irritation
Headache with N+V – raised ICP or meningeal irritation.
Confusion, seizures.
CN III palsy – posterior communicating artery aneurysm.
Describe the effect of endothelial injury in the pathogenesis of DIC
The injury exposes the subendothelial matrix which can activate the platelets and coagulation pathway.
This causes thrombi to form due to fibrin deposition.
List risk factors for basal cell skin cancer
Radiation exposure Gene mutations – TP53 gene mutations in BCC Arsenic exposure through ingestion – Treat asthma and psoriasis Immunosuppression Xeroderma pigmentosum Nevoid basal cell carcinoma syndrome Bazex syndrome Previous nonmelanoma skin cancer Skin type – albinism Rombo syndrome Alcohol consumption Hydrochlorothiazide use – potent photosensitizer
Which genes have been linked to an increases risk of focal ischaemic CVA
Mutations in F2, F5, NOS3, ALOX5AP and PRKCH
Risk of additional ischaemic injury due to extravasated blood is of greatest significance in SAH in which locations
Basal SAH
Vasospasm can involve the major vessels of the Circle of Willis.
What is the most frequent cause of spontaneous SAH
Rupture of a saccular (berry) aneurysm
They are found in ~2% of population
List the most common causes of DIC
Malignancy Sepsis Major trauma Obstetric events Hypoxia, acidosis and shock can all cause endothelial injury and contribute to DIC.
List the microscopic features of cellulitis
Clusters of neutrophils
Invading adipose tissue extensively -> Fat necrosis
Seen in deeper tissue
List some of the potential complications of haemorrhagic CVA
A large proportion of survivors will be left with some form of neurological deficit which will depend on the site and size of the haemorrhage and therefore the location and extent of damaged tissue
It is possible however to have a gradual improvement of the deficits that are left over weeks to months following the event as the haematoma is gradually removed
What skin and hair changes may be experienced by ICU patient’s
Lots of ICU survivors experience dry skin and hair loss.
Usually improves with time
What is rombo syndrome
Autosomal dominant condition distinguished by basal cell carcinoma and atrophoderma vermiculatum, trichoepitheliomas, hypotrichosis milia, and peripheral vasodilation with cyanosis
List the morphological features of global cerebral ischaemia
The brain will become oedematous and swollen and so the gyri will widen and the sulci will narrow
The will be poor demarcation between the white and gray matter on the cut surface.
Over time the microscopic features of irreversible ischemic injury will evolve and they mimic the changes in infarcts
Which types of basal cell carcinoma will get radiation therapy
Advanced and extended lesion that are not suitable for surgery
Can be due to allergy to anesthetics, current anticoagulant therapy
List potential differentials for normal pressure hydrocephalus
Other forms of dementia Cervical myelopathy All urinary problems Parkinson’s disease Depression Etc.
List the macroscopic features of basal cell carcinoma
Present as pearly papules containing prominent dilated sub-epidermal blood vessels (telangiectasias)
Advanced lesions may ulcerate and cause extensive local invasion of bone or facial sinuses
List risk factors for presence of berry aneurysms
Increased incidence in 1st degree relatives.
Increased incidence with certain Mendelian disorders - AD PCKD, Ehlers-Danlos type IV, NF1, Marfan’s, fibromuscular dysplasia of extracranial arteries, and coarctation of aorta.
Other predisposing factors: cigarette smoking and HTN.
Which medical therapies are used for the treatment of high-grade sarcoma
Ifosfamide and doxorubicin-based chemotherapy
List causes of haemorrhagic CVA
Hypertension Cerebral amyloid angiopathy (CAA) Trauma Aneurysm rupture, Anticoagulation Vasculitis Thrombolysis Coagulopathy Arteriovenous malformations Venous and cavernous angiomas Intracranial neoplasms Cocaine use
Why do symptoms develop rapidly in an extradural haemorrhage
Rapidly evolving since blood under high arterial pressure is extravasating from the vessel into the potential space between the periosteum and the dura
List risk factors for developing HAP
The biggest risk factor is mechanical ventilation - very common in ICU.
Also severe underlying disease, immunosuppression, prolonged antibiotics and invasive instrumentation like catheters.
All may be seen in ICU
What is an extradural haemorrhage
The accumulation of blood in the (potential) space between the periosteal dura and the bone
How do you distinguish between focal and global ischaemic brain injury
The distinction between them is not due to pathological differences but rather the amount of brain that is involved.
What are the 2 most serious subtypes of brain herniation
Uncal herniation- displacement of the medial part of the temporal lobe (uncus) below the tentorium cerebelli
Tonsillar herniation- the cerebellar tonsils are forced downwards through the foramen magnum, causing compression on the brainstem (fatal if left untreated)
What happens when the intracranial compensatory mechanisms become exhausted
This is when no further drainage of blood or CSF is possible.
At this point, the equilibrium becomes disrupted and the patient enters adecompensated statewhere intracranial pressure will begin to rise
What is the most serious form of skin cancer
Malignant melanoma
What is the most common cause of wound infection following orthopedic surgery
S aureus and coagulase-negative staphylococci
Describe the pathological features of the vessels in haemorrhagic CVA
Any vessel affected by cerebral amyloid angiopathy will be rigid and therefore will not collapse during processing and sectioning
The hyaline material that is deposited in CAA is not made from collagen like it is in normal hyaline arteriosclerosis but rather b amyloid
Describe the features of a class 4 - dirty/infected surgical wound
Purulent inflammation present
Preoperative perforation of viscera
Penetrating traumatic wounds >4 hours
List the main complications of raised ICP
Seizures
Stroke
Neurological damage
Death
List the macroscopic features of wound infection
Purulent discharge from surgical site or wound or drain placed in the wound
Discoloration of tissues both within and at the wound margins
Friable, bleeding granulation tissue
Lymphangitis - red line spreading from wound
What is non-communicating hydrocephalus
Occurs when the flow of CSF is blocked along one or more of the narrow
passages connecting the ventricles.
Aqueductal stenosis results from a narrowing of the aqueduct of Sylvius,
(between the third and fourth ventricles)
Describe the natural progression of squamous cell skin carcinoma
If untreated they will destroy nearby healthy tissue
Then spread to the lymph nodes or other organs which can be fatal
What is the most common cause of wound infection following head and neck surgery
S aureus, streptococci, anaerobes and streptococci present in an oropharyngeal approach
What effect can DIC have on the kidney
The kidneys may have small thrombi in the glomerulus which can lead to reactive swelling, microinfarcts or even bilateral renal cortex necrosis.
Steroids improve the outcome in diffuse axonal injury - true or false
False
The make it worse
The kidney failure seen in ICU patients is always temporary - true or false
False
It can be short-term/temporary in some cases
BUT
In others it can become a lifelong disease (may need dialysis).
Describe the inflammatory phase of wound infection
Begins with coagulation cascade to limit bleeding
Platelet reaction & reversible opening of endothelial cell junctions to allow passage of neutrophils and monocytes
Inflammatory exudate fills the wound in hours
What is brain herniation
A shifting of the brain parenchyma itself in response to high ICP
The rate of CSF drainage by a shunt can be altered - true or false
True
VP shunts have pressure valve (palpate behind auricle) that can be set
with a specially designed magnet/kit.
Can be set to drain more or less CSF by changing rate based on patient needs
Describe a local wound infection
Local infection is contained in one location, system or structure.
Occurs when bacteria or other microbes move deeper into the wound tissue and proliferate at a rate that invokes a response in the host
List the potential GCS scores for verbal response
5 – Orientated response 4 – Confused conversation 3 – Inappropriate words 2 – Incomprehensible sounds 1 – No response
Why might ICU patients end up with longer term breathing issues after their stay
If the patient was on a ventilator their chest muscles will become weaker.
May require chest exercises or physio to improve breathing.
Describe the pathogenesis of haemorrhagic CVA caused by CAA
Ab peptides are deposited in the walls of medium and small cortical, meningeal and cerebellar vessels
Once the vessels walls have amyloid deposited within them it weakens them which makes them more vulnerable to rupture = haemorrhage
How does normal pressure hydrocephalus present
Hakim’s triad: abnormal gait, urinary incontinence, dementia
Why do babies get massive heads with hydrocephalus
Because their fontanelles haven’t fused so the skull can expand to cope with pressure
Not seen in adults’
Repeat bleeding is common in SAH - true or false
True
prognosis worsens with each bleed
How common are CVAs
They are incredibly common
Someone in the UK has a CVA every 3.5minutues
15million people suffer a CVA annually worldwide
¼ of individuals in the UK who suffer a CVA will die within a year and >1/2 that survive will be left with a permanent disability
Which countries have the highest rates of melanoma
Australia and New Zealand
10-20% arise in the head and neck region
Incidence is increasing worldwide though
It is common for children to present with a skull # and extradural haemorrhage - true or false
False
Children have a deformable skull which means that temporary displacement of skull bones can lacerate underlying vessels without fracture.
In adults, a fracture is likely to be seen.
What are the most common causative organisms of HAP
Most common organisms are gram +ve cocci (s.aureus) and gram -ve rods (enterobacteriaceae and pseudomonas)
Which processes initiate ARDS
ALI/ARDS is initiated by the injury of pneumocytes and pulmonary endothelium
It begins a cycle of inflammation and lung damage
Squamous cell skin carcinoma is more common in which sex
2-3 times more common in men than women due to higher cumulative lifetime UV exposure
What can cause reactive gastritis
The main cases are severe trauma, burns, intracranial disease, major surgery, severe illness and other forms of physiological stress
List surgical management options for raised ICP
Surgical decompression
Remove mass lesions
CSF diversion
What are lobar haemorrhages
Haemorrhages that effect the lobes of the cerebral hemispheres
Type of haemorrhagic CVA
What determines the prognosis of ARDS
Prognosis varies with age of the patient, cause and the number of organs involved.
Cause - pneumonia 86% and trauma 38% mortality
3 organs or more is invariably fatal
What is communicating hydrocephalus
This is when the flow of CSF is blocked after it exits the ventricles.
Called communicating because the CSF can still flow between the
ventricles, which remain open
What causes a fat emboli
They occur in those that have suffered large fracture
Can also get bone marrow emboli
What are the 3 subtypes of reactive gastritis ulcers
Stress ulcers
Curling ulcers
Cushing ulcers
Describe the process of endothelial activation in ARDS
Occurs early on
Pneumocyte injury is sensed by the alveolar macrophages which then start to secrete mediators like TNF which act on the nearby endothelium
Another mechanism is via circulating inflammatory mediators which activate it directly - occurs in sepsis or systemic illness
Some cells will get damaged by the mediators in the process, but others start to express adhesion molecules, procoagulant proteins and chemokines.
A GCS score of 8 or below requires which interventions
GCS ≤8 indicates intubation
ICP monitoring where GCS ≤8 w/ abnormal CT head
What can cause ARDS
Can be caused by direct lung injury or occur secondary to severe systemic illness
Several genes have been linked to ARDS - mostly linked to coagulation or inflammation
What effect does an extradural haemorrhage have on the surrounding structures
As it enlarges, it strips the dura from the bone but is restrained at the sutures
Gives the convex/lemon shaped appearance
Describe the maturation phase of wound infection
Dominant features – wound contraction, scar formation, remodeling
Which type of CVA is more common - ischaemic or haemorrhagic
Ischaemic - they account for 82-92% of CVA’s
What is the most common cause of ganglionic intracerebral haemorrhage
Hypertension
Associated with deep brain (ganglionic) parenchymal haemorrhages.
Where do most berry aneurysms present
90% of saccular aneurysms are near major arterial branch points in the anterior circulation
Multiple aneurysms exist in 20-30% of cases
What increase the risk of developing ICU delirium
Increased risk from infection, kidney, heart or lung failure and certain drugs.
Specific patients will also be at a higher risk: elderly and those with existing memory/cognitive issues.
List possible symptoms seen in a vertebrobasilar artery stroke
Vertigo Nystagmus Diplopia Visual field defects Dysphagia Dysarthria Facial hypaesthesia Syncope Ataxia
What can cause an increased production of CSF
Choroid plexus papilloma
ICU survivors are two to five times more likely to die compared with age and sex-matched population controls - true or false
True
Haemorrhagic CVAs are most common in which age group
They most often occur in mid to late adult life ( peak incidence approx 60yrs)
Describe the features of a class 1 - clean surgical wound
Uninfected operative wound No acute inflammation Closed primarily Respiratory, gastrointestinal, biliary, and urinary tracts not entered No break in aseptic technique Closed drainage used if necessary
What are the two main microscopic patterns of basal cell carcinoma
Multifocal superficial type – Multifocal growths originating from the epidermis and sometimes extending
Nodular lesions growing downward deeply into the dermis as cords and islands of variably basophilic cells w/ hyperchromatic nuclei, embedded in a mucinous matrix and often surrounded by fibroblasts and lymphocytes
List the macroscopic features of cellulitis
Swelling, erythema, warmth
Petechiae or hemorrhage
Necrotic
Involves deeper dermis and subcutaneous fat
Describe how the release of TNF can trigger DIC
It causes the endothelial cells to express tissue factor and decrease thrombomodulin expression which tips the balance towards coagulation
It also promotes the adhesion of leukocytes (via adhesion molecule expression) which damage the cells.
These processes can cause widespread deposition of fibrin within the microvasculature (forms clots)
Describe the humoral theory of cerebral blood flow autoregulation
Theory is that it is the action of metabolic by-products that controls flow
It is common to see microbleeds in the brains of those with CAA - true or false
True
They have weakened vessels that are prone to rupture
ARDS can occur as a result of cardiopulmonary bypass - true or false
True
List the most common symptoms of DIC
Microangiopathic anaemia
Dyspnoea, cyanosis and respiratory failure
Oliguria and acute renal failure
Bleeding and bruising – can occur anywhere
Convulsions and coma
Circulatory collapse and shock
What determines the survival of an ischaemic portion of the brain
It will depend on the duration of the ischemia, the magnitude and rapidity of the reduction of blood flow an the presence of collateral circulation
These factors also determine the clinical presentation of cerebrovascular disease as they determine the site and size of the damaged area
What is the biggest predictor of prognosis in reactive gastritis
How quickly/easily the underlying condition can be treated
Describe the treatment of ARDS
No specific treatments for ALI/ARDS
Overview - admit to ICU, give supportive therapy and treat the underlying cause.
Supportive resp - CPAP or most need careful ventilation
Supportive circulation - monitoring and careful fluid management
Most need nutritional support
Ventilation usually needed at high pressure due to stiffening of the lungs.
Which type of CVA do bone marrow emboli typically cause
Focal ischemic CVA
Appears as widespread haemorrhagic lesions in the white matter
Describe the typical appearance of a basal cell carcinoma
Waxy papules with central depression Pearly appearance Erosion or ulceration, often central Bleeding, especially when traumatized Crusting Rolled (raised) border Translucency Telangiectases over the surface Slow growing (0.5 cm in 1-2 y)
What is DIC
It is an acute, subacute or chronic thrombohaemorrhagic disorder that is characterised by the excessive activation of the coagulation pathway and the formation of thrombi in the microvasculature
What is the main mechanism of death in reactive gastritis
Fatal GI bleeds or the consequences of GI perforation.
One study reported a mortality rate of 46% in critically ill patients with GI bleeding, compared with 21% inpatients without bleeding.
Describe the pathogenesis of reactive gastritis
Biggest underlying cause is thought to be local ischaemia.
This can be caused by systemic hypotension or reduced blood flow caused by stress-induced vasoconstriction of the vessels supplying the GI tract.
Redistribution of blood flow occurs in conditions like sepsis
In some cases, there is increased release of the vasoconstrictor endothelin-1 which also contributes
List some of the complications associated with drains and catheters
Central venous catheters can result in bloodstream infections
Urinary catheters have a high risk of causing UTI
List the microscopic features of ARDS
Diffuse alveolar damage, interstitial and intra-alveolar damage, inflammation and fibrin deposition are all seen.
Inflammation characterised by scattered neutrophils and macrophages
Presence of the waxy hyaline membranes in the alveoli - consisting of fibrin-rich oedema and necrotic epithelial cells
Describe the role of metabolic autoregulation in the autoregulation of cerebral blood flow
Arterioles dilate in response to chemicals, e.g. lactic acid and CO2
What is pulmonary oedema
The presence of excess interstitial fluid within the alveoli
It can result from haemodynamic disturbances (cardiogenic) or increased capillary permeability due to microvascular injury (non-cardiogenic).
How is the GCS score used
Generally used to categorise traumatic brain injury into mild (13-15), moderate (9-12) and severe (3-8)
Part of the APACHE II scoring system, which is used to predict ICU mortality
How common are wound infections
A survey sponsored by WHO demonstrated a prevalence of nosocomial infections in the range of 3-21%, with wound infections accounting for 5-34% of the total
It is possible to determine whether a CVA is ischemic or haemorrhagic from the clinical presentation alone -true or false
False
Not possible
List potential complications of aneurysm clipping
Stroke Seizure Vasospasm Bleeding The clip being placed incorrectly so that it does not stop the bleeding or blocks another artery
List some of the complications associated with tracheostomies
Patients will be unable to speak to begin with which can be distressing.
Will leave a scar.
What are ganglionic haemorrhages
Haemorrhages effecting the basal ganglia and thalamus
Type of haemorrhagic CVA
What is the most common region of the brain to get a focal ischemic CVA due to an emboli
The territory supplied by the middle cerebral artery
It is as common for each hemisphere in this territory to be effected
How does sepsis cause DIC
Endotoxins released in sepsis can inhibit endothelial expression of thrombomodulin directly or indirectly by stimulating immune cells to make TNF
Can also activate factor XII
These trigger coagulation
Antigen-antibody complexes are also sometimes produced in response to infection and can activate the classic compliment pathway and secondarily activate platelets = coagulation
List the consequences of PPI treatment
PPI low incidence of adverse effects or drug interactions.
Describe the pathogenesis of a haemorrhagic CVA
Brain tissue is damaged due to a raise in ICP
Blood from the ruptured vessels compresses the surrounding tissue causing it to become infarcted.
The presence of the blood in the parenchymal tissue and the associated oedema will raise the ICP pressure which will damage the brain tissue
The brain also becomes infracted due to a loss of blood supply
The blood that is leaking from the ruptured vessels was intended for somewhere so the site it was intended for will become ischemic
What is the normal ICP in a newborn
1.5-6 mmHg (often < 0)
What are the main causes of subarachnoid haemorrhage
Trauma - typically associated with underlying parenchymal injury.
e.g. RTA
Vascular abnormality (AV malformation or aneurysm)
The onset of DIC is always sudden - true or false
False
It can be sudden - e.g. in sepsis
However in other cases it can be more insidious and chronic - e.g. in malignancy or dead foetus
Describe the myogenic theory of cerebral blood flow autoregulation
Theory is that it is a direct reaction of smooth muscle to the stretch
How are surgical wounds classified
Class 1 - clean
Class 2 - clean-contaminated
Class 3 - contaminated
Class 4 - dirty infected
Obstruction to CSF flow leads to what
Hydrocephalus
This causes increase ICP
Head injury is a common cause of death and disability in RTAs - true or false
True
Some cells in the CNS will be more sensitive to ischemia than others - true or false
True
Neurones are the most sensitive
Astrocytes and glial cells are also particularly sensitive
List symptoms of severe cellulitis infections
Systemic – violaceous color and bullae Lymphangitic spread, crepitus, hemodynamic instability Cutaneous hemorrhage Skin sloughing Skin anesthesia Rapid progression Gas in the tissue
Uraemia can cause ARDS - true or false
True
Describe how PTCH mutations lead to basal cell carcinoma
PTCH protein is a receptor for sonic hedgehog (SHH), a component of the Hedgehog signaling pathway
Typically have a germline loss-of-function mutation in one PTCH allele
The second normal allele is inactivated in tumours by an acquired mutation, usually caused by exposure to mutagens (particularly UV light)
In this ‘off’ state PTCH exists in a complex with another transmembrane protein called SMO
Binding of SHH to PTCH releases SMO
This activates the transcription factor GLI1 which turns on the expression of genes that support tumor cell growth and survival
List the pathological features of lacunar infarcts
They are lake shaped, hence the name, <15mm wide and can be single or multiple
Microscopically they show gliosis surrounding areas of tissue loss
The vessels that are effected can also have a widening of their perivascular spaces which is termed etat crible
What is the purpose of craniotomy in haemorrhagic CVA
To remove the collected blood and damaged brain tissue to relive the pressure on the surviving brain
Done if bleeds are large
Which features of haemorrhagic CVA suggest a poor prognosis
A low GCS suggests a high mortality and poor prognosis
A large blood volume at presentation also suggests a poorer prognosis
Very large bleeds or bleeds that extend into the ventricular system can be devastating
Which age group is most prone to facial cellulitis
adults > 50 yo
List complications of shunts for hydrocephalus
Mechanical failure
Infections
Obstructions
Which type of CVA do fat emboli typically cause
Focal ischemic CVA
They tend to cause shower embolisation
How can hydrocephalus be classified
As communicating vs non-communicating
As congenital vs acquired
Or by aetiology
List local complications of wound infection
Delayed and non-healing of wound
Abscess formation
How do CVAs caused by fat emboli typically present
Present with generalised cerebral dysfunction, a lack of localising signs and disturbances of higher cortical function
Describe the neurogenic theory of cerebral blood flow autoregulation
Theory is that it is the action of perivascular nerves that controls flow
List potential causes of pulmonary oedema due to undetermined origin
High altitude
Neurogenic - CNS trauma
List the microscopic features of melanoma
Cells are usually larger than normal melanocytes
They have enlarged nuclei with irregular contours and chromatin clumped at periphery of nuclear membranes
Prominent red nucleoli (eosinophilic)
ICP is determinant of cerebral perfusion pressure - true or false
True
CPP = MAP – ICP
List the macroscopic features of melanoma
Striking variations in color, appearing in shades of black, brown, red, dark blue and gray
Zones of white or flesh-colored hypopigmentation appear on occasion due to focal regression
Irregular and notched border
Radial growth – horizontal spread of melanoma within the epidermis and superficial dermis
Vertical growth phase – is often heralded by the appearance of a nodule
What is the GCS scored out of
15
eyes out of 4
verbal response out of 5
motor response out of 6
Which parts of the brain may be involved in a intra-parenchymal brain haemorrhage
Selective involvement of the crests of gyri, where the brain is in contact with the inner surface of the skull (frontal & temporal tips, orbitofrontal surface)
Petechial haemorrhages in an area of previously ischaemic brain, usually following the cortical ribbon.
“Lobar” haemorrhage involving subcortical white matter and often with extension into the SAS.
Centred in the deep white matter, thalamus, basal ganglia, or brainstem; may extend into the ventricular system.
List common ICU interventions/devices that often lead to complications
Ventilators Tracheostomy IV lines and pumps Feeding tubes Drains and catheter Drugs
What is ICP
Theintracranial pressure
It is the pressure within the cranium of the skull
It is measured in millimeters of mercury mmHG
What determines the extent of a focal ischaemic CVA
The duration of the ischemia and the extent of collateral blood supply
This also determines the size, location and shape
List the macroscopic features of reactive gastritis
Lesions range from shallow erosions to ulcers that penetrate the gastric mucosa.
The ulcers are typically rounded, under 1cm in diameter and usually have a black/brown base due to staining by the acid digesting blood products.
These lesions are found anywhere in the stomach and usually occur in multiples.
What are the 3 main injury categories in RTA
Acceleration/ deceleration (may occur even w/out an impact)
1 impact w/ vehicle
2 impact w/ road or stationary object
How do you treat wound infection
Antibiotic prophylaxis
Each surgical specialty, body region and operation type needs to have its strategy to treat due to different microbial spectrum
Early surgical debridement - however, re-opening of surgical site can cause significant morbidity
Sepsis Treatment – antibiotics
Where do most basal cell carcinomas occur
Occurs mostly on face, head and neck, and hands
Which organisms commonly cause wound infection
Patient’s own endogenous flora
e.g. staphylococci (S.aureus strain is most common), MRSA, streptococci, enterococci
List the macroscopic features of non-haemorrhagic infarcts
There will not be much change in their appearance in the first 6 hrs of irreversible injury
The tissue will be soft, swollen and pale and the gray-white matter junction will become indistinct by 48hrs
Between 2-10 days - The brain will become friable and gelatinous
As oedema resolves in the viable adjacent tissue the ill defined border between infracted and normal tissue will become defined
The tissue will then liquefy which will eventually leave a cavity that is filled with fluid which c will keep expanding until all dead tissue has been cleared. This occurs from day 10 and lasts for 3 weeks
List the clinical features of high-grade sarcoma
Gradually enlarging painless mass
Can become quite large, esp. in thigh and retroperitoneum
Pain or symptoms associated with compression by the mass – paresthesias or edema in an extremity
Constitutional symptoms rarely – fever and/or weight loss
Which systemic factors can increase the risk of wound infection
Age Malnutrition Hypovolemia Poor tissue perfusion Obesity Diabetes Steroids and other immunosuppressants
What would happen if a brain tumour continued togrow without intervention
The intracranial pressure will rise to such a degree that the final cranial component, the brain parenchyma, will shift in position and become displaced, this is termedherniation
Which operative characteristics can increase the risk of wound infection
Poor surgical technique Lengthy operation Intraoperative contamination Prolonged preoperative stay in the hospital Hypothermia
List some acceleration/deceleration injuries than may be seen in RTA
Diffuse axonal injury - caused by shearing forces on brain
Aortic dissection - shearing forces generated by arch of aorta continuing forward whilst descending aorta anchored to thoracic spine
How does hydrocephalus affect the surrounding brain tissue
The excess fluid increases the size of the ventricles and puts pressure on the brain.
This can damage brain tissues and cause a range of impairments in brain function.
Describe the structure of the pia mater
Adherent to the brain parenchyma and spinal cord.
Thin and highly vascularised - helps nourish the underlying neural structures
Describe the typical appearance of a squamous cell carcinoma of the skin
Preceded by actinic keratoses
A shallow ulcer with heaped-up edges, covered by a plaque
Which organisms are the most common of cellulitis from bite wounds
Capnocytophaga canimorsus (dog) Eikenella corrodens (human) Pasteurella multocida (dog or cat) Streptobacillus moniliformis (rat)
What causes berry aneurysms
Aetiology is unknown but absence of SM and intimal elastic lamina in affected vessel suggests that they are developmental abnormalities.
When might you see burns in a RTA
May see if vehicle catches fire but unlikely in RTCs otherwise
List the complications of TPA treatment used in focal ischaemic CVAs
Haemorrhagic CVA Hypotension Fluid accumulation on the brain Pericarditis Cardiac tamponade Arrhythmia Heart failure Fluid accumulation in the lungs Seizures Swelling of the vocal cords Internal bleeding
List potential causes of haemodynamic pulmonary oedema
Left-sided heart failure Volume overload Pulmonary vein Hyperalbuminemia Kidney (nephrotic or protein-losing enteropathies) and liver disease Infections - e.g. bacterial pneumonia Lung trauma Liquid aspiration Inhales gases -
Which masses can lead to an increase in ICP
Tumour Infarct Contusions Haematoma Abscess
They distort surrounding brain by increasing pressure
Hypersensitivity reactions to what substances can cause ARDS
Drugs
Organic solvents
How common is reactive gastritis in ICU patients
Most patients admitted to ICU will have some histological evidence of gastric mucosal damage.
In 1-4% of these patients, the bleeding is so severe that transfusions are required.
