Monitoring Anaesthesia Flashcards

1
Q

What should be observed during anaesthesia? What can be monitored using equipment?

A
  • depth
  • mucous membranes
  • pulse
  • chest movement
  • pupil size
  • responses to surgery
  • blood loss
  • urine output?
    machines
    > respiratory gases
    > pulse ox
    > blood pressures
    > ECG
    > thermometer
    > blood gases
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2
Q

What can be used to assess depth of anaesthesia?

A
  • eye position
  • presence of nystagmus
  • lacrimation
  • pupil size and response to light
  • nuero responses (eg. cranial nerve reflexes)
  • muscle relaxation (jaw, neck)
  • EEG changes (people)
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3
Q

What does capnography measure? How can arterial CO2 be estimated?

A
  • CO2 in resp gases
  • end-tidal and inspired CO2
  • End tidal = Alveolar = Arterial CO2
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4
Q

Normal PaCO2?

A

35-45mmHg

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5
Q

How can kPa be calculated from hhMg?

A

divide mmHg by 7.5 to give kPA

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6
Q

At waht PaCo2 is IPPV warranted?

A

> 60mmHg

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7
Q

Causes of hypercapnia?

A
  • alveolar hypoventilation
  • ^ CO
  • hyperthermia
  • bicarbonate administration
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8
Q

Causes of hypocapnia?

A
  • v CO (eg. shock)
  • hyperventilation/shallow breaths
  • artefact
  • hypothermia
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9
Q

What shape is the normal capnogram?

A
  • log increase from baseline, alveolar plateaux phase, sharp drop to baseline (where end tidal values measured)
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10
Q

What can changes in the capnograph indicate?

A
  • rebreathing
  • asthma
  • cardiogenic oscillations -> ripple effect
  • VQ mismatch
  • tachypnoea
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11
Q

What is FI/ET anaesthetic agent concentration useful for?

A
  • helps assess depth
  • need to know MAC for this to be useful
  • useful when using v low flows in circle system
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12
Q

How can oxygenation be assessed?

A
  • cyanosis
  • pulse ox
  • blood gases
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13
Q

What does pulse ox tell you? What does it not tell you?

A

Saturation of Hbg (SpO2%)
pulse rate
adequate tissue perfusion? (be aware may squash underlying vessels and give false reading)
- does NOT measure ventilation

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14
Q

How is oxygen delivery calculated?

A

Oxygen content x CO

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15
Q

Normal SpO2 range? What do low number indicate?

A

95-100%

<60mmHg = hypoxaemia

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16
Q

What is spirometry similar to?

A

Peto tube measuring airspeed in planes

17
Q

Causes of low SpO2 on 100% oxygen?

A
  • oxygen supply, probe position, BP may be affected reading, alpha 2 agonist given??
    > R->L shunt
  • anatomical shunt
  • intrapulmonary shunt (VQ mismatch) esp horses
    > diffusion impaired (rare)
18
Q

What effect does 2,3 DPG have on the O2 dissociation curve?

A

shifts it right

2,3-DPG produced in chronic anaemia

19
Q

What does ECG not tell you?

A
  • cardiac output
  • blood pressure
  • mechanical activity of the heart
20
Q

What methods of measuring blood pressure are there?

A
  • Invasive (direct, IBP)
  • Non-invasive (NIBP) > doppler (cats true value between mean and systole) and oscillometry (tends to under read, MAP value most accurate)
21
Q

Normal BP systole, diastole and mean?

A
  • 100-160mmHg systole
  • 60-100mmHg diastole
  • 80-120mmHg mean
  • mean must stay above 60 or renal perfusion will fall
22
Q

Where does the transducer of invasive blood pressure probes need to be positioned?

A
  • point of shoulder in dorsal recumbency
  • manubrium sternea in lateral
    > at level of the heart
23
Q

Tx for blood pressure dropping < 60-70mmHg?

A
  • reduce depth
  • fluid bolus (5-10ml/kg)
  • inotropes (dopamine, dobutamine)
  • AVOID NSAIDs
24
Q

Which blood gases are analysed for which parameters?

A
  • arterial = ventilation

- venous = acid/base balance

25
Q

How can PaO2 be calculated from inspired O2?

A

PaO2 = 5 x FiO2

26
Q

How are serious hypoxaemia and critical hypoxaemia defined?

A

Normal PaO2 >80mmHg

Serious hypox PaO2 <40mmHg

27
Q

What should the PaO2/FiO2 be greater than?

A

300

28
Q

What does PaO2 tell you?

A

How well the lungs can oxygenate blood

29
Q

What does the arterial CO2 tension (PaCO2) tell you?

A

Measure of alveolar ventilation

  • normally similar to ETCO2 in healthy animals
  • Arterial - alveolar PCO2 may be larger if lungs diseased or during thoracotomy
30
Q

How are hypo and hyper ventilation defined by PaCO2 parameters?

A

normal 35-45
hypo >45
hyper <35mmHg

31
Q

Where is core temperature most accurately measured from?

A

rectum or oesophagus

32
Q

Which patients are at greatest risk of developing hypothermia?

A

small

33
Q

Which animals are very susceptible to hypoxaemia?

A

Horses (when breathing 100% oxygen PaO2 should be ~500mmHg, may be ~60mmHg!!)

34
Q

What level of PaO2 = risk of cardiac arrest?

A

<40mmHg