Case 24- Pathology Flashcards
Approach to a patient with a fracture
- Mechanism of injury
- High energy- ABCDE
- Physiology of patient- extremes of age
- Associated co-morbidities
Open fracture
The bone fragment communicates with the outside. You can have inside out or outside in. Inside out is when the bone pokes out of the skin. Outside in could be when there is gun powder around the bone
• Higher risk of contamination
• Generally high energy trauma
• More soft tissue injury
• Delayed healing or non-union due to loss of heamatoma
• Soft tissue cover required- otherwise infection will occur
Managing a patient with a fracture
- Wound care
- Pain management
- Imaging- Generally plain Xrays
- Fracture care- conservative or surgical
- Reduction, immobilisation- most important
- Conservative- Plaster/ splints
- Operative- Fixation
- Early movements
Clinical symptoms of a fracture
- Pain
- Deformity
- Bone crepitus
- Abnormal mobility
- Associated soft tissue injury
- Neurovascular comprimise
Fracture classification
- Growth plate involvement- Skeletally mature/immature
- Anatomy- location- proximal/distal, diaphysis, metaphysis, epiphysis
- Extent- complete/ incomplete
- Orientation- transverse/ oblique/ spiral
- Displacement- Non displaced/ displaced, angulated
- Fragmentation- comminuted/ segmental
- Soft tissue- open/ closed
Direction of fracture- LARA
• Length- two parts of the bone move away from each
• Alignment- the two parts of the bone tilt away from each other
• Rotation
• Apposition- one part of the bone moves slightly to the side
Where is the fracture= Intra-articular and Extra-articular
Complication of bone fractures
• Neurovascular injuries
• Compartment syndrome
• Infection
• Long term- stiffness, arthritis, instability, growth disturbances, non-union, avascular necrosis, complex regional pain syndrome
• General- DVT/PE, Chest infection/ UTI/ Pressure sores
Growth arrest- the growth plates may fuse together
Anaesthesia
- “Insensitivity to pain, especially as artificially induced by the administration of gases or the injection of drugs before surgical operations.”
- Not the same as analgesia – typically used to refer to reduced sensitivity to pain
- Local anaesthesia – insensitivity to pain in a specific area
- General anaesthesia – insensitivity to pain everywhere; also involves loss of consciousness (or a dissociative state)
When is a single anaesthetic used
In simple, short surgical procedure
The variety of anaesthetics used during surgery
- A sedative premedication (e.g. a benzodiazepine)
- An intravenous anaesthetic for rapid induction (e.g. propofol)
- A perioperative opioid analgesic (e.g. alfentanil or remifentanil)
- An inhalation anaesthetic to maintain anaesthesia during surgery (e.g. nitrous oxide and isoflurane)
- A neuromuscular blocking agent to produce adequate muscle relaxation (e.g. vecuronium)
- An antiemetic agent (e.g. ondansetron)
- A muscarinic antagonist to prevent or treat bradycardia or to reduce bronchial and salivary secretions (e.g. atropine or glycopyrrolate)
- An anticholinesterase agent towards the end of the procedure (e.g. neostigmine) to reverse the neuromuscular blockade
- An analgesic for postop pain relief (e.g. an opioid such as morphine and/or a NSAID)
Stage 1 of anaesthesia- Analgesia
- Analgesia (depends on agent)
- Amnesia
- Euphoria
Stage II of Anaesthesia: Excitement
Excitement, Delirium and Combative behaviour
Stage III Anaesthesia: Surgical anaesthesia
Unconsciousness, Regular respiration, Decreasing eye movement
Stage IV of Anaesthesia: Medullary depression
- Respiratory arrest
- Cardiac depression and arrest
- No eye movement
Stages of Anaesthesia- Danger
- Stage 2 is the dangerous “excitement” stage.
- Irregular respiration and heart rate, possible uncontrolled movements, vomiting and breath holding.
- Since the combination of spastic movements, vomiting, and irregular respirations may lead to airway compromise, rapidly acting drugs are used to minimize time in this stage and reach stage 3 as fast as possible.
Mechanisms of general anaesthesia
- Change in excitability- inhalational anaesthetics in particular tend to hyperpolarise neurons, generally through activation of K+ channels
- Changes in synaptic signalling- both IV and volatile anaesthetics influence synaptic transmission; in general these effects are potentiation of GABA A and glycine signalling and inhibition of NMDA-R’s but reductions in presynaptic calcium signals are also seen
- Changes in action potential firing- many anaesthetics have a modest effect on sodium channels
Intravenous anaesthetic
- Parenteral anesthetics are the most common drugs used for anesthetic induction of adults
- High lipophilicity, coupled with the relatively high perfusion of the brain and spinal cord, results in rapid onset and short duration after a single bolus dose.
- These drugs ultimately accumulate in fatty tissue.
- Each of these anesthetics has its own unique properties and side effects
Iv anaesthetic half lives are ‘context sensitive’
- Drug t1/2 varies greatly from drug to drug, as might be predicted based on their differing hydrophobicities and metabolic clearances.
- After a single bolus of thiopental, patients usually emerge from anesthesia in ~ 10 min; however, it may take more than a day to awaken from a prolonged thiopental infusion.
- Most individual variability is due to PK factors, e.g., in patients with lower cardiac output, the relative perfusion of the brain and the fraction of anesthetic dose delivered to the brain are higher; so patients in septic shock or with cardiomyopathy usually require lower doses of parenteral anesthetics.
- The elderly also typically require a smaller parenteral anesthetic dose, primarily because of a smaller initial volume of distribution.
Common parenteral general anaesthetics
Thiopental, Etomidate, Ketamine, Propofol
How do Propofol and etomidate act
- Propofol and etomidate act (at least in part) through potentiation of GABA A receptors
- Potentiating actions of the intravenous anaesthetics, propofol (PROP) and etomidate (ETOM) on α2β3γ2 GABAA receptors
How do Propofol and etomidate act
- Propofol and etomidate act (at least in part) through potentiation of GABA A receptors
- Potentiating actions of the intravenous anaesthetics, propofol (PROP) and etomidate (ETOM) on α2β3γ2 GABAA receptors
Propofol
- Propofol is the most commonly used parenteral anesthetic
- Formulation is an emulsion in soybean oil (possible allergen) and water.
- MOA is believed to be primarily GABA-A, with different subunits mediating analgesia and sedation. Some effect also on nicotinic receptors and voltage gated sodium channels
- Because of its fast induction and recovery time, propofol is also widely used for sedation of infants and children undergoing MRI. It is also often used in combination with ketamine as the two together have lower rates of side effects
- One of propofol’s most frequent side effects is pain on injection, especially in smaller veins. This pain arises from activation of the pain receptor, TRPA1, found on sensory nerves and can be mitigated by pretreatment with lidocaine.