Intra Operative complications

Question 1

Why do complications occur?

Answer 1

Patient factors
Procedure factors
Anaesthesia factors

Question 2

What are the common complications?

Answer 2

• Three “Hs”
  –Hypotension
  –Hypothermia
  –Hypoventilation (hypercapnia, hypoxaemia)
• Other complications
  –Bradycardia
  –Tachycardia

Question 3

What does blood pressure need to be above to avoid hypotension?

Answer 3

• MAP > 60 mmHg to maintain vital organ
  perfusion (Doppler > 90mmHg)
• Hypotension
• MAP < 60 mmHg

Question 4

What are the causes of hypotension?

Answer 4

*reduced CO, SV, HR,
Vascular resistance
*Drugs
*hypovolaemia

Question 5

Tx of hypotension?

Answer 5

1. Check cuff, repeat reading
2. Check plane of anaesthesia and reduce
3. Check heart rate
   - Treat if low
4. Give fluid therapy
   - Crystalloids 10ml/kg iv over 10-15 minutes
5. Drugs

Question 6

What are the consequences of hypotension?

Answer 6

• Organ/tissue damage
  –Acute kidney injury
  –Myopathy (in horses)
• Severe hypotension
  –Poor perfusion of heart
  * Arrhythmias
  * Death

Question 7

What are the causes of hypothermia?

Answer 7

Hypothermia = <37*C
–Increased heat loss
–Reduced heat production
–Abolished behavioural responses
–Alterations in hypothalamic function from
anaesthetic drugs

Question 8

How do you prevent hypothermia?

Answer 8

• Pre-operative warming
• Blankets
• Bubble wrap
• Warm air
• Heated mats
• Heat and moisture exchanger (HME)

Question 9

What are the consequences of hypothermia?

Answer 9

• Cardiovascular and haematological
  –Arrhythmias = > can be
  fatal
  –Coagulopathies
  –Reduced immune
  function = > post op
  infection
• Metabolic
  –Reduced drug metabolism
  = > prolonged effects
  and delayed recoveries
  –Shivering = > increased O2 demand

Question 10

What can hypoventilation lead to?

Answer 10

Hypercapnia
Hypoxaemia

Question 11

What are the causes of hypoventilation?

Answer 11

• Effects of drugs on
  –CNS
  –Respiratory muscles
• Positional changes
  –Dorsal vs sternal
  recumbency

Question 12

What is hypercapnia
What is normal values?
when would you treat?

Answer 12

Hypercapnia = high co2 in blood
* Normal CO2 35-45 mmHg
* Hypercapnia > 45 mmHg
* Treatment if ETCO2 > 60mmHg

Question 13

Hypercapnia Tx?

Answer 13

1) Lighten plane of anaesthesia
–Reduce vaporiser setting
–Reduce rate of drug
administration
2) Mechanical ventilation
–Squeezing reservoir bag
–Intermittent Positive
Pressure Ventilation
(IPPV)

Question 14

What is hypoxaemia?
When would you treat?
What animals are more at risk?

Answer 14

• Reduced level of O2 in blood
• Measured either
  –Sampling arterial blood (PaO2)
  –Via pulse oximeter (SpO2)
• Treatment if SpO2 < 90 mmHg or PaO2 < 60
  mmHg
  *Horses more at risk

Question 15

Causes of hypoxaemia?

Answer 15

1. Not enough oxygen delivered
2. Profound hypoventilation
3. Impaired gas exchange
4. Airway obstruction
5. Severe hypovolaemia

Question 16

Tx of hypoxaemia?

Answer 16

1. Increase oxygen up to 100%
   2.Start mechanical ventilation
2. Disease –Bronchodilators
   Positional compression – head up, recruitment manoeuver
3. Check ETT for mucous/blood, change ETT
4. ‘Shock’Fluid therapy, vasopressors

Question 17

Bradycardia causes?

Answer 17

–Increased parasympathetic system activation
* Drugs
* Vagal response
–Hypothermia
–Disease e.g.
* Hyperkalaemia
* Raised intra cranial
pressure (ICP)

Question 18

Tx of bradycardia?

Answer 18

• If MAP > 60 mmHg no
  need to treat
• If MAP < 60 mmHg
  –Antagonise drugs
  –Give parasympatholytics
• Due to disease
  –Treat underlying diseases
  e.g. hyperkalaemia, ICP

Question 19

Tachycardia causes?

Answer 19

–Increased sympathetic tone
* Pain
–Hypovolaemia
–Hyperthermia
–Hypercapnia

Question 20

Consequence of tachycardia?

Answer 20

• Cardiac dysfunction
  –Heart failure
  –Malignant arrhythmias
  –Death

Question 21

Tx of tachycardia?

Answer 21

• Treat underlying cause
  –Pain = analgesics
  –Hypovolaemia = restore
  circulating volume
  –Hyperthermia = cool
  –Hypercapnia = reduce
  anaesthetic plane, start
  ventilation