Trauma and burns Flashcards
Factors determining the severity of electrical injuries
Magnitude of current and duration of exposure are the two most important factors
Size of the current: the greater the current (in amperes) the worse the injury. This is the most important determinant of electrical injury; the severity is the most directly related to amperage. Current in excess of 5A can cause sustained asystole.
Duration of the current: the longer the duration of exposure, the worse the burn
Type of circuit – AC current worse than DC
Magnitude of the voltage: the higher the voltage, the greater the damage. > 1000 V is high voltage and causes greater tissue damage
Tissues traversed by the current: the most important examples being the brain and heart.
Contact conduction vs. arcing: i.e. current arcing though ionised air causes surface flash burns which may be diffuse, whereas contact with an electrode causes burns at the specific site of contact.
Presence of a surface conductor, eg. water. Wet skin has its normally high resistance reduced a hundred-fold, with a much larger
Contraindications for resuscitative thoracotomy
No signs of life witnessed in the pre-hospital setting
Prolonged pre-hospital CPR
Asystole on presentation, and no cardiac tamponade
Massive extrathoracic injuries which may be unsurvivable
Accepted indications for resusciatative thoractotomy
Penetrating injury with -
- previously witnessed cardiac activity
- unresponsive hypotension (<70) despite vigorous fluid resus
Blunt thoracic injury with -
- rapid exanguination from chest tube (1500ml immediately returned)
- unresponsive hypotension (<70) despite vigorous fluid resus
Relative/controversial indications of resuscitative thoracotomy
Penetrating thoracic injury with traumatic arrest without previously witnessed cardiac activity
penetrating non-thoracic injury (eg abdominal) with traumatic arrest with previously witnesses cardiac activity
Blunt thoracic injuries with traumatic arrest with previously witnessed cardiac activity
what is Resuscitative thoracotomy
a procedure of last resort that is nearly always performed in the emergency department and involves gaining rapid access to the heart and major thoracic vessels through an anterolateral chest incision or clam shell incision to control exsanguinating haemorrhage or other life-threatening chest injuries
what is “Traumatic asphyxia”
“a form of suffocation where respiration is prevented by external pressure on the body”
features of traumatic asphyxia
Common features:
- Cyanosis of the upper body, especially the face
- Conjunctival haemorrhage
- Conjunctival oedema
- Petechial haemorrhages and purpura over the face, neck and upper face
- Oedema and congestion of the head
The “brassiere sign” - petechhii and congestion of asphyxia spare those areas of the thorax which were covered by tight-fitting clothing, as it obstructs cutaneous blood flow and prevents the formation of petechii.
Uncommon features:
- Chemosis
- Exophthalmos
- Retinal haemorrhages and visual loss
- Vitreous haemorrhagic exudates
- Retrobulbar (posterior orbital) haemorrhages
- Haemotympanum
Other sequelae:
- Loss of consciousness
- Seizures
- Blindness
- Hearing loss
- Cerebral venous infarction
specific management issues of penetrating neck injury
Requires management at a trauma centre with appropriate expertise. May require multiple speciality input - interventional radiology, ENT, vascular, cardiothoracic.
A)
Assess for airway compromise (eg. by expanding haematoma)
Assess for airway injury (eg. subcutaneous emphysema)
Organise expert help.
Awake fiberoptic intubation by an experienced operator would be ideal, with an ENT surgeon on standby. Risks include intubating a false passage, or causing complete tracheal disruption.
B)
Assess for respiratory compromise.
Ausculation and percussion may reveal pneumothorax due to injury of the dome of pleura, or the raised hemidiaphragm of a phrenic nerve injury
C)
Assess the circulation in the arm on the affected side. There may be vascular compromise.
Angiography is very important; occlusion balloons may be very useful in controlling haemorrhage from deep vessels.
D)
Assess the neurology of the patient, starting with GCS.
Verterbral artery damage may present with spinal syndromes (eg. Brown-Sequard) or brainstem stroke signs
Carotid artery damage may present with hemispheric stroke signs
Definitive Mx -
Urgent surgical exploration required for haemodynamic compromise, expanding or pulsatile haematoma, extensive subcutaneous emphysema, stridor, or neurological deficit with intra op bronchoscopy/ endoscopy/ angiography if available.
If no indication for urgent surgical exploration requires CT angiography (or equivalent) with close observation in ICU +/- flexible laryngoscopy +/- endoscopy +/- oral contrast swallow study.
Specific concerns in a Zone 1 neck injury:
massive haemothorax
arteriovenous fistula (subclavian vessels)
Thoracic duct damage (if it was the left side of the neck, as it tends to be with a right-handed attacker coming from the front)
brachial plexus damage
Horner’s syndrome
Root of the neck and contents
the junction between the thorax and the neck
Subclavian artery and branches
- vertebral artery
- internal thoracic artery
- thyrocervical trunk
- costocervical trunk
Subclavian vein and tributaries (EJV)
Trachea
Oesopahagus
Vagus nerve
Recurrent Laryngeal nerve
Dome of pleura
Brachial plexus
Lymphatics and thoracic duct
Phrenic nerve
Sympathetic chain, stellate ganglion
Scalene muscle.
Clavicle
Issues specific to pregnant trauma
A)
risk of difficult airway.
aspiration risk.
B)
The respiratory function is impaired by decreased FRC;
chest drains higher, so as to avoid the pushed-up diaphragms
Maintain resp alkalosis - paco2 30mmHg in late pregnancy.
C)
signs of shock will develop late.
Vena cava compression means the patient needs to be positioned at a 30° tilt
Neonatal and foetal welfare
- Pelvic binders are inappropriate
- Pelvic fractures may threaten the near-term foetus
- Placental abruption may result in massive haemorrhage and needs to be excluded early in the primary survey
- Foetal heart rate monitoring is essential
- Early transfer to an O&G-equipped hospital is essential
- Retroperitoneal haemorrhage from dilated pelvic veins can be difficult to assess without ultrasound
- A vaginal examination needs to be performed, looking for amniotic fluid (a pH of 7.0-7.5 will confirm this - the normal vaginal pH is much lower than this)
Transfusion and general haematology issues
- Rhesus-negative mothers need to receive IV immunoglobulin at least within 48 hours of the trauma
- Transfusion needs to be Rh compatible
- The pregnant trauma patient is in an even more hypercoagulable state than the normal trauma patient, and thus requires special attention to DVT prophylaxis
Drug choices
- Antibiotic choices are limited; tetracyclines and fluoroquinolones are to be avoided
- If urgent caesarian delivery is planned, intubation drugs wil affect the foetus; thus there is need for NICU involvement for ventilation
Issues to consider in investigations and the secondary survey
- need for Rh blood grouping to prevent Rh isoimmunisation (where the mother is Rh negative and the foetus is Rh positive).
- An abdominal ultrasound (FAST) is still performed, with additional focus on the uterus; uterine rupture or placental abruption need to be detected early.
- Foetal welfare can be monitored by CTG, and the O&G specialist should be invited to perfrom their own focused ultrasound to investigate the pregnancy.
- Though radiation exposure is undesirable, it is tolerated (particularly in late term pregnancy) because organogenesis has already taken place, and because the risk from ionising radiation exposure is minute in comparison to the risk of missed injuries and haemorrhage.
Pathophysiology of heat stroke:
Exposure to high temperature leads to an increase in the cardiac output, cutaneous vasodilation and sweating.
Dehydration by sweating leads to hypovolemia and salt loss
In the absence of plentiful water and salt, sweating becomes impossible and thermoregulation is thus impaired.
As the convective cooling is now impossible, the core body temperature increases.
As the core temperature increase, enzyme function is altered and cellular energy production becomes impaired
Direct heat-related tissue damage results in cytokine release
At the same time, hypovolemia and shock lead to bacterial translocation from the gut, leading to endotoxaemia
The cytokine response to this endotoxin load results in a systemic inflammatory response
Due to this SIRS, the vascular endothelium is damaged, leading to multi-organ system failure and DIC.
Factors that affect prognosis of heat stroke:
College answer -
- initial core temp
- duration of hyperthemia
- presence of comorbidities
LDH, CK and AST levels (when extremely high) were predictive of non-survivors in a study of heat-stroked Haj pilgrims
Failure to decrease the core body temperature to below 38.9° within the first 30 minutes of presentation.
A hyperdynamic circulation is protective, but a sluggish hypodynamic circulation is associated with a poorer survival
Found collapsed at home (as opposed to public place or care facility)
Preexisting cardiac disease
Use of diuretics
High body temperature
Low Glasgow Coma Score
Low platelet count
Prolonged prothrombin time
High serum creatinine
High SAPS II score
Use of vasoactive drugs within the first 24 hrs in the ICU
expected changes on routine investigations in the presence of heat stroke.
ABG: acidosis, probably mixed metabolic. FBC: haemolysis, thrombocytopenia and anaemia EUC: renal failure, hyperkalemia CMP: hyperphosphataemia LFTs: raised transaminases and bilirubin. Specifically, AST and LDH will be raised. CK: elevated Urinary myoglobin Coagulopathy (DIC): raised PT and APTT
Options for cooling methods:
Evaporation of cold water sponges
Ice packs
Immersion in ice water
Contact cooling by blankets and jackets
Iced gastric, colonic, bladder, or peritoneal lavage
Infusion of cold intravenous fluids
Invasive technique such as cooling of the dialysis circuit, or ECMO
Goals of therapy in heat stroke -
Early, aggressive cooling to under 39°C
Support of multiple failing organ systems
Change in the pattern of injuries associated with morbid obesity
Injury scores are lower in obese patients
Pattern of blunt trauma is different
Injuries that are more likely:
- pulmonary contusion
- rib fractures
- pelvic injuries
- knee dislocations
- extremity fractures
- proximal upper extremities seem to get it worst
Injuries that are less likely:
- head injuries
- liver injuries
Influence of morbid obesity of FAST assessment
Morbid obesity is one of the limitations of FAST
Difficult insonation of the appropriate spaces; image quality is likely to be poor
Pericardial fat can be misinterpreted as clotted blood
Perinephric fat may be misinterpreted as intraperitoneal free fluid
The advantage is, if you can’t fit into the CT scanner this is all you’ve got.
injuries that require specific positioning or immobilisation of the patient
Head injury
C-spine injury - lie flat, and be log-rolled.
Clearance of the C-spine should occur as soon as it is practical
There are many problems with wearing a collar for a prolonged period (eg. pressure areas, increased ICP, and so forth)
T/L spine injuries- lay flat, log rolled, increased risk VAP
Severe chest injuries - Do not lie them with the flail segment down. That lung has probably had a contusion anyway. Lie them “good lung down” - oxygenation will improve.
Gentle lateral rotation may be appropriate
Pelvic # - while unfixed; binder, flat, firm mattress, log roll, flat lift hoist
Long bone # - traction significantly limits movement
Competing interest
- Airway vs. C-spine collar:
Airway wins; the collar can be removed and inline stablisation attempted for intubation
- Head injury vs. C-spine injury:
Head injury wins, even if the C-spine is unstable the ICP must be managed properly. Remove the collar and sandbag the neck. Paralyse and sedate the patient.
If they must remain flat, then angle the bed so the head is still up.
Measuring Intra abdominal pressure
Patient is supine and no active abdominal muscle contractions
Clamp the urinary catheter, after ensuring it is freely flowing and not obstructed.
25 ml of sterile saline is instilled into the bladder via a port in the urinary catheter catheter and the catheter filled with fluid
A pressure transducer is connected to the urinary catheter, between the clamp and the bladder
Allow 30-60 seconds after instillation of the saline so as to allow for bladder detrusor muscle relaxation
Zero transducer at the mid-axillary line and at the level of the iliac crest
Measure pressure at end-expiration
Intra-abdominal Hypertension (IAH)
a sustained IAP ≥12 mmHg
Abdominal Compartment Syndrome (ACS)
sustained IAP >20 mmHg (with or without APP <60 mmHg) that is associated with new organ dysfunction OR as IAH-induced new organ dysfunction without a strict IAP threshold
Abdominal Perfusion Pressure (APP)
MAP – IAP
How to measure IAP
- Patient is supine and no active abdominal muscle contractions
- Clamp the urinary catheter, after ensuring it is freely flowing and not obstructed.
- 25 ml of sterile saline is instilled into the bladder via a port in the urinary catheter catheter and the catheter filled with fluid
- A pressure transducer is connected to the urinary catheter, between the clamp and the bladder
- Allow 30-60 seconds after instillation of the saline so as to allow for bladder detrusor muscle relaxation
- Zero transducer at the mid-axillary line and at the level of the iliac crest
- Measure pressure at end-expiration
adverse cardiorespiratory effects of an increase in IAP in a mechanically ventilated patient
Cardiac
Decreased cardiac output –
- Reduced venous return - due to intrabdominal venous compression and raised intrathoracic pressure.
- Increased systemic afterload – due to increased compression of intrabdominal arterial vessels, and PVR due to raised intrathoracic pressure.
- Decreased Right Ventricular output from raised intrathoracic pressure, raised PVR Increased CVP and LVEDP
- Reduced compliance - due to elevation of diaphragm displacing the heart and increased afterload
- Hypotension – decreased cardiac output.
Respiratory
- Deteriorating O2 A-a gradients due to increased – raised diaphragm and atelectasis, increased intrapulmonary shunt / V/Q mismatch
- Hypercapnia – decreased chest wall and lung compliance.
- Increased airway pressure – altered respiratory compliance.
Warning signs for airway burns
Burns occurred in an enclosed space
Stridor, hoarseness, or cough
Burns to face, lips, mouth, pharynx, or nasal mucosa
Soot in sputum, nose, or mouth
Dyspnoea, decreased level of consciousness, or confusion
Hypoxaemia (low pulse oximetry saturation or arterial oxygen tension) or increased carbon monoxide levels (>2%)
Complications of burns on legs
Compartment syndrome and limb ischaemia Rhabdomyolysis Escharotomy Amputation Infection Scarring Peripheral nerve compression Contracture Pain DVT Loss of function
Generic approach to assessing a patient with burns
A) - Airway burns
B) - Carbon monoxide or cyanide poisoning
C) - Hypotension, hypovolemia, adequacy of fluid resuscitation;
- problems gaining vascular access
D) - Decreased level of consciousness, head injury; analgesia
E) - Electrolyte disturbance
- Exposure and assessment of total burned areas
F) - Urine output
Emergency management issues in drowning
A)
Assessment of the airway and of the need for immediate intubation.
B)
Drowning is associated with a high risk of aspiration (and not just of lake water).
Ventilation with high FiO2
High PEEP, 12-15
Investigation of possible aspiration with CXR and ABG
C)
Establishment of IV access and correction of hypovolemia;
drowning victims may become hypovolemic following prolonged immersion due to the hydrostatic effects of water (particularly salt water)
D)
Investigate causes of drowning related to intracranial events, eg. ICH, or trauma resulting from a fall into submerged obstacles
E)
Assessment of temperature, and rewarming actively to 34 and passively above (the immersed patient is invariably hypothermic, as it is rare to drown in a body of water with an ambient temperature higher than human core body temperature).
