Anaesthethics: Complications of Anaesthetics Flashcards
Give some respiratory complications of general anaesthetics
1) Injury to lips, tongue, gum, dentition and other oral soft tissue structures
2) Injury to structures of glottis e.g. epiglottis, vocal cords and cartilage
3) Sore throat
4) Bronchospasm/laryngospasm
5) Aspiration of gastric contents
6) Injury to trachea, bronchial structures or alveoli
7) Pulmonary oedema
8) Pharyngeal obstruction
9) Hypoxia
10) PE (postoperative setting)
What may injury to glottic structures result in?
Transient changes in voice, stridor, laryngospasm
Who is bronchospasm and laryngospasm more common in in general anaesthetics?
1) Those with hyper-responsive airways e.g. asthma, recent respiratory tract infection.
2) Can also occur following aspiration of gastri contents during anaesthesia
Presentation of bronchospasm and laryngospasm?
- hypoxia
- increased CO2
- reduced ventilation
- classical wheeze (bronchospasm)
- high pitched stridor (laryngospasm)
Does a wheeze indicate bronchospasm or laryngospasm?
Bronchospasm
Does a high pitched stridor indicate bronchospasm or laryngospasm?
Laryngospasm
Who is at increased risk of aspiration of gastric contents in GA?
1) Non-fasted patients with increased intra-abdo pressure
2) Impaired lower oesophageal sphincter competence
3) Pregnant women
4) Obese individuals
5) Hiatus hernias
6) Impairment laryngeal reflexes
7) Reduced GCS
Clinical features of aspiration of gastric contents in GA?
- bronchospasm
- laryngospasm
- hypoxia
- increased airway pressures: may collapse a lung lobe secondary to bronchial obstruction
- pneumonia
How may injury to the trachea, bronchial structures or alveoli following an episode of anaesthesia present?
Subcutaneous emphysema or pneumothorax.
N.B. Pneumothorax may also result from the rupture of pre-existing bullae.
When may pulmonary oedema occur in GA?
Pulmonary oedema may occur in patients following laryngospasm or airway obstruction, especially during the recovery phase from anaesthesia.
Inspiratory effort against the closed glottis leads to excessive negative pressure within the alveoli resulting in pulmonary oedema.
When should you suspected pulmonary oedema after GA?
Pulmonary oedema should be suspected in hypoxic patients following laryngospasm.
Presentatin of pulmonary oedema in GA?
- hypoxia following laryngospasm
- fine bi-basal crepitations
Why is pharyngeal obstruction common in GA?
Due to sedation following anaesthesia, especially when using long-acting sedative agents.
What condition may worsen pharyngeal obstruction in GA?
Obstructive sleep apnoea
How can pharyngeal obstruction be identified?
Snoring
Management of pharyngeal obstruction?
- basic airway manoeuvres
- place patient in lateral position
- overnight CPAP may be required following a general anaesthetic.
What can cause hypoxia in GA?
Hypoxia is common among patients immediately following GA and is multifactorial:
- 2ary to anaesthetic agents and opioid analgesia
- atelectasis
Who is more prone to hypoxia in GA?
- pre-existing respiratory disease
- obese patients
- patients following upper abdominal or thoracic surgeries
What type of operations are more prone to hypoxia?
Abdo & thoracic surgeries
Give some CVS complications of general anaesthetics
1) Hypotension
2) Arrhythmias
3) HTN
Give some causes of hypotension following GA
1) Anaesthetic agents: can reduce the contractility of the heart and slow the heart rate –> However, the effects of most of these agents are short-lived, and other causes of hypotension should be considered.
2) Haemorrhage (resulting in hypovolaemia)
3) Reduced vascular tone
If hypotension persists following GA despite initial management, what should be considered?
Other causes e.g. myocardial infarction, pulmonary embolism and pneumothorax
Give some causes of arrhythmias following GA
Can be both bradycardia and tachycardia.
1) Post-op pain
2) Anxiety
3) Electrolyte imbalances
4) Cardiac surgery
5) Myocardial infarctions/ischaemia
6) Hypoxia/hypercarbia
7) Acid-base imbalances
8) Worsening of pre-existing arrhythmias
Causes of HTN following GA?
1) Worsening of poorly controlled essential hypertension
2) Pain
3) Anxiety
4) Bladder distension
5) Fluid overload
6) Hypoxemia
7) Hypercarbia
8) Hypothermia
Give some genitourinary complications of general anaesthetics
1) AKI
2) Urinary retention
Acute kidney injury (AKI) is a common complication in the postoperative period.
How may it present?
1) Reduction in urine output
2) Worsening of metabolic parameters (e.g. acid-base balance and electrolyte imbalance)
Who is more at risk of developing urinary retention post GA?
- older patients
- BPH
- spinal anaesthesia
Give some GI complications of general anaesthetics
1) Post-op N&V
2) Ileus
What is post-operative nausea and vomiting (PONV) a direct complication of?
anaesthetic agents and opioid analgesics
Risk factors for PONV?
- female sex
- non-smokers
- post-op opioid use
- previous history of PONV
- type of surgery
- general anaesthesia
- volatile anaesthesia
What types of surgery are higher risk for PONV?
- laparoscopic surgery
- cholecystectomy
- gynaecological surgery
- middle ear surgeries
- squint corrections
What can be given to patients at high risk of PONV?
Prophylactic antiemetic drugs are usually given
Risk factors for post-op ileus?
- type of surgery: GI surgery, open repair of abdominal aortic aneurysms, and other surgical procedures where bowel handling may occur.
- use of opioids
- hyperkalaemia
Give some neuro complications of general anaesthetics
1) post-op cognitive dysfunction
2) peripheral nerve injuries (positioning-related)
What is postoperative cognitive dysfunction (POCD)?
A decline in cognition apparent after a patient recovers from the acute impact of surgery and hospital stay.
May present as acute delirium or be more subtle (e.g. memory impairment, difficulty comprehending etc.).
Risk factors for postoperative cognitive dysfunction?
- increasing age
- lower educational level
- cerebrovascular disease
What can cause peripheral nerve injuries?
prolonged durations in certain positions without appropriate preventive strategies.
Preventative measures to avoid injury to brachial plexus?
1) Avoid stretch or direct compression at the neck/axilla
2) Avoid using shoulder braces to support the Trendelenburg position.
3) Minimise shoulder abduction (aim <90 degrees) and avoid external rotation.
4) Avoid rotation and flexion of neck to the opposite side, try to keep head in neutral position throughout.
Preventative measures to avoid injury to radial nerve?
Avoid compression of the lateral humerus
Preventative measures to avoid injury to ulnar nerve?
Padding at the elbow, forearm supination, avoid elbow extension and extreme flexion.
Preventative measures to avoid injury to common peroneal nerve?
Pad lateral aspects of the upper fibula, avoid extreme lithotomy position and avoid lithotomy position for more than 2 hours
Inadvertent perioperative hypothermia (IPH) is a common consequence of general and regional anaesthesia.
What is IPH defined as?
Core body temp <36 degrees.
Who is at a higher risk of develoing hypothermia during anaesthesia?
- high ASA grade
- combined regional & general surgery
- emergency major surgery
- low BMI
Adverse effects of IPH?
- surgical site infection
- coagulopathy
- increased transfusion requirements
- pain
- altered drug metabolism
- adverse cardiac events.
Preventative measures to avoid IPH?
1) Keeping patients warm during the pre-operative phase
2) Active warming during the intraoperative phase with fluid warmers and forced air warming blankets
3) Keeping the patient covered during the recovery
Give 3 key complications of regional anaesthesia
1) Post-dural puncture headache (PDPH)
2) Peripheral nerve injuries
3) Neuro complications following central neuraxial blocks (CNB)
What is a post-dural puncture headache (PDPH)?
Occurs following an intentional dural puncture (with a spinal needle) or unintentional dural puncture (with an epidural needle).
The leak of CSF through the dural defect causes intracranial hypotension leading to traction on intracranial structures.
When does PDPH typically occur?
72 hours after dural puncture
Describe headache in PDPH
- usually frontal or occipital
- worsened by standing or sitting up
- relieved by lying down
Management of PDPH?
1) refer to anaesthetic team
2) exclude other causes of acute headache
3) bed rest
4) adequate hydration
5) avoiding situations which would give rise to an increase in intracranial pressure
6) simple analgesics
7) epidural blood patch: can be performed if headache persists