348366
Description
Mind Map by melian.yates, updated more than 1 year ago
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Created by melian.yates
about 11 years ago
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Peri-operative Accidents & Emergencies
- Physiological
- Respiratory Arrest/ Dyspnoea/Apnoea
- Apneoa (Total arrest of breathing)
- Results in severe Hypoxia
& Hypercapnia =>
Cardiopulmonary Arresst
- 1) De novo: Acute event that stops breathing)
- 2) End-result of progressive unintended hypoventilation
- A) Neural unresponsiveness to
blood-gas dereangements
- Signs of severe
CNS depression
- B) Mechanical
obstruction/restriction to gas
flow (or ineffective ventilation)
- Lung inflation:
- Low Pressures
- Upper airway
obstruction or
CNS depression
- Upper airway
obstruction or
CNS depression
- High Pressures
(Stiff lungs)
- Pneumothorax or
Bronchospasm
- Pneumothorax or
Bronchospasm
- Low Pressures
- Lung inflation:
- Signs of severe
CNS depression
- A) Neural unresponsiveness to
blood-gas dereangements
- 3) Sign of cardiac arrest
- Results in severe Hypoxia
& Hypercapnia =>
Cardiopulmonary Arresst
- TX: (Cause dependent)
- CNS Depression
- Ventilation should be
supported mechanically or
manually until cause is
identified and
amerliorated
- End Anaesthesia
if cranial nerves
indicate
overdosage
- IV Anesthetic Overdose:
- Ventilate (DON'T
Hyperventilate) the
lungs until the drug
redistributes to
skeletal muscle
- If no breathing after 5
min -> Hyperventialtion
may have cause
Hypocapnia => Reduce
Resp. rate to 2
breaths/min
- Last resort: Opiod
antagonists (Naloxone) &
Analeptics (Doxapram)
- Ventilate (DON'T
Hyperventilate) the
lungs until the drug
redistributes to
skeletal muscle
- Ventilation should be
supported mechanically or
manually until cause is
identified and
amerliorated
- Obstructed Gas Flow
- Cleared or bypassed
(tracheostomy)
- Vomit aspiration:
- Positioned head down, (Conscious) mouth
gagged, oropharynx cleared of
material using dry swabs (held
with towel forceps or haemostats),
moistened swabs
- Unconscious:
Endotracheal
intubation & PPV w/
O2, Endotracheal
suction & lavage
- Will be life saving in
most cases, however
the application of O2
alone is useless if the
victim is not breathing
- Will be life saving in
most cases, however
the application of O2
alone is useless if the
victim is not breathing
- Positioned head down, (Conscious) mouth
gagged, oropharynx cleared of
material using dry swabs (held
with towel forceps or haemostats),
moistened swabs
- Cleared or bypassed
(tracheostomy)
- CNS Depression
- Apneoa (Total arrest of breathing)
- Cardiopulmonary Arrest
- Causes:
- Myocardial Hypoxia
- Systemic Hypoxia
- Insufficient O2 in the
arterial blood perfusing
the myocardium
- Insufficient O2 in the
arterial blood perfusing
the myocardium
- Local Cardiac Effect
- CO may be too low to
ensure it's own
oxygenation under normal
working conditions
- Hypotension
- Inferred Clinically:
Imperceptible pulses in the
periphery, diminished blood
flow at the surgical site
- Severe or prolonged hypotension
diminishes perfusion in splanchic &
renal vasculature => Post-op failure
in these organs
- Equine: Post-anaesthetic
myositis => May result from
prolonged muscle hypoperfusion
- Equine: Post-anaesthetic
myositis => May result from
prolonged muscle hypoperfusion
- Myocardium depends
on adequate Diastolic
BP to maintain its own
perfusion
- (Severe) => Diminishes
coronary blood flow
=> Cardiac arrest
- (arterial)BP = CO x SVR
- CO = SV x HR
- CO = SV x HR
- Tx:
- Infuse fluids rapidly
- Decreased contractility: Inotropes (Dobutamine)
- Decreased SVR: Alpha 1 agonists (Phenylephrine)
- Decreased SVR: Alpha 1 agonists (Phenylephrine)
- Decreased contractility: Inotropes (Dobutamine)
- Infuse fluids rapidly
- Inferred Clinically:
Imperceptible pulses in the
periphery, diminished blood
flow at the surgical site
- Bradycardia
- Very low HR => insufficient
to maintain an adequate
Diastolic BP required for
coronary perfusion
- Very low HR => insufficient
to maintain an adequate
Diastolic BP required for
coronary perfusion
- Arrythmias
- Result of myocardial
hypoxia, or (by
reducing cardiac
output) be the cause of
hypotension
- Often indicate
poor
management
- Causes:
- SNS activation: Light
anaesthesia, Hypoxia,
Hypercapnia, Hypotension,
Hypoglycaemia
- Drugs: Alpha2 agonists,
halogenated hydrocarbons
+ adrenaline
- Electrolyte abnormalities (esp. K+)
- Certain surgical procedures
- Pre-existing heart disease
- Medical conditions
e.g. gastric dilation
volvulus complex
- SNS activation: Light
anaesthesia, Hypoxia,
Hypercapnia, Hypotension,
Hypoglycaemia
- Tx:
- ECG for Dx
- Drugs required depend on
arrhythmia present
- Adequate anaesthesia
& Ventilation restores
normal rhythm
- In Electro-mechanical
dissociation (EMD) the ECG
appears normal, but there is
no mechanical activity of the
heart, No palpable pulses
- In Electro-mechanical
dissociation (EMD) the ECG
appears normal, but there is
no mechanical activity of the
heart, No palpable pulses
- Drugs required depend on
arrhythmia present
- ECG for Dx
- Result of myocardial
hypoxia, or (by
reducing cardiac
output) be the cause of
hypotension
- Hypotension
- Workload of the
heart is
overwhelmingly
increased
- Hypertension
- Tachycardia
- Myocardium O2
requirement > delivery
- Most common cause
of negative myocardial
O2 balance
- Difficult to define/ Tx if:
- The trend is dangerous & unchanging
- The rate is of Haemodynamic significance
- The ECG shows signs of myocardial hypoxia
- If steps not taken to restore a +ve
myocardial O2 balnce, ventricular
premature complexes (VPCs) will arise
=> Ventricular fibrilation (VF)
- The trend is dangerous & unchanging
- Myocardium O2
requirement > delivery
- Hypertension
- CO may be too low to
ensure it's own
oxygenation under normal
working conditions
- Systemic Hypoxia
- Myocardial Hypoxia
- Causes:
- Toxaemia
- Depresses myocardial
contractility & excitability
- Feature of many diseases
(require extensive pre-op
preparation)
- Azotemia in renal diseases
- Lactacidaemia in Hypovolemic shock
- Diabetic keto-acidosis
- Endotoxaemia in canine pyometria
- Endotoxaemia in canine pyometria
- Diabetic keto-acidosis
- Lactacidaemia in Hypovolemic shock
- Tx:
- Correcting underlying condition & restoring
perfusion (mainly by restoring effective circulating
blood volume)
- Correcting underlying condition & restoring
perfusion (mainly by restoring effective circulating
blood volume)
- Anaesthetic overdose
can be regarded as a
toxaemia
- Depresses myocardial
contractility & excitability
- Electrolyte Disturbances
- Hyperkalaemia
- Most Important!
- Addison's disease
- Iatrogenic
- Renal failure
- Major injury/burns
- Acidaemia
- Acidaemia
- Major injury/burns
- Renal failure
- Iatrogenic
- Tx:
- Resolving initiating
cause & rapidly
lowering [K+] levels by:
- Hyperventilation
- Fluids
- HCO3-
- Ca gluconate
- Insulin glucose
- Peritoneal dialysis
- Peritoneal dialysis
- Insulin glucose
- Ca gluconate
- HCO3-
- Fluids
- Hyperventilation
- Resolving initiating
cause & rapidly
lowering [K+] levels by:
- Most Important!
- Hyperkalaemia
- Hypothermia
- Under anaesthesia:
- Hypothalamic thermoregulation impaired
- Blood vessels (skin) vasodilate
- Skeletal muscle activity ceases
- Shivering is inhibited
- Visceral surfaces exposed
- Inspired gases are cold & dry
- Inspired gases are cold & dry
- Visceral surfaces exposed
- Shivering is inhibited
- Skeletal muscle activity ceases
- Blood vessels (skin) vasodilate
- Hypothalamic thermoregulation impaired
- Animals most at risk:
- High surface to volume
ratios (e.g. neonates, birds,
small lab animals
- Underdeveloped/impaired
thermoregulatory reflexes
(Age extremes)
- High surface to volume
ratios (e.g. neonates, birds,
small lab animals
- Effects:
- Reduced alveolar ventilation (VA)
- Reduced HR & CO
- LT-shifted oxyhaemoglobin
dissociation curve
- Increased blood viscosity
- Shivering (recovery) elevates O2
consumption & plasma catecholamines
- Shivering (recovery) elevates O2
consumption & plasma catecholamines
- Increased blood viscosity
- LT-shifted oxyhaemoglobin
dissociation curve
- Reduced HR & CO
- Reduced alveolar ventilation (VA)
- Consequences:
- Prolonged recoveries
- Decreased elimination of volatile agents
- Decreased drug redistribution, elimination
- Decreased BMR
- Self-reinforcing cycle
- Self-reinforcing cycle
- Decreased BMR
- Decreased drug redistribution, elimination
- Decreased elimination of volatile agents
- Cardiac arrest
- Ventricular fibrilation is
likely when T falls below
28 degrees C
- Ventricular fibrilation is
likely when T falls below
28 degrees C
- Prolonged recoveries
- Prevention:
- Physical Factors
- Increase operating room
environment T
- Insulate surfaces animals lay on
- BAIR Hugger, aluminum
foil, bubble wrap, heater
blankets, hot water bottles,
heat lamps
- Heat incoming fluids
- Heat incoming fluids
- BAIR Hugger, aluminum
foil, bubble wrap, heater
blankets, hot water bottles,
heat lamps
- Insulate surfaces animals lay on
- Increase operating room
environment T
- Anaesthetic Factors
- Use short acting anaesthetics
- Ensure anaesthetic depth
is not excessively deep
- Adequate, not excessive, ventilation
- Rebreathing systems where appropriate
- Rebreathing systems where appropriate
- Adequate, not excessive, ventilation
- Ensure anaesthetic depth
is not excessively deep
- Use short acting anaesthetics
- Surgical Factors
- Avoid unnecessary wetting, clipping,
volatile preparations (alcohol)
- Minimize surgical time
- Technique (exposed visceral
surfaces moistened w/ warm
irrigation fluids)
- Avoid wetting non-surgical areas
- Minimize incision
size, Viscera replaced
in body cavity ASAP
- Avoid wetting non-surgical areas
- Technique (exposed visceral
surfaces moistened w/ warm
irrigation fluids)
- Minimize surgical time
- Avoid unnecessary wetting, clipping,
volatile preparations (alcohol)
- Physical Factors
- Tx:
- Post-op: thoroughly dry animal
with towels, heaters (plastic bags
for small lab animals)
- Post-op: thoroughly dry animal
with towels, heaters (plastic bags
for small lab animals)
- Under anaesthesia:
- Respiratory Arrest/ Dyspnoea/Apnoea
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