AMP 45: Monitoring the anesthetized patient

Question 1

A patient is breathing 100% oxygen, what is the expected oxygen saturation on pulse oximetry?

Answer 1

SO2 should not be less than 98%

SpO2 < 95% should spur re-evaluation

Question 2

What is the ideal PaO2 in a patient breathing 100% O2?

Answer 2

500 mm Hg

V/Q mismatch from atalectasis or physiologic shunt makes this usually slightly lower

Question 3

What are the differentials for a patient developing cardiac arrhythmias during anesthesia?

Answer 3

• myocardial hypoxemia/hypoperfusion
• systemic acidosis
• specific anesthetic drugs (e.g., thiopental, ketamine)

Question 4

What CVP should indicate that your patient may be becoming fluid overloaded?

Answer 4

CVP approaching 8 cm H2O

Question 5

What colloid osmotic pressure (COP) warrants colloid administration?

Answer 5

COP < 15 mm Hg

Question 6

What is the ideal plane of anesthesia for surgery?

Answer 6

light to medium stage III anesthesia

for a surgical plane of anesthesia the palpebral reflex may be sluggish but does not need to be absent

Question 7

Explain how the eye position in dogs changes from awake to deep anesthesia

Answer 7

eyeball position in awake and stage II: central
stage III (light and medium): medioventral
stage III (deep): central

central eye position indicates either too light or too deep anesthesia

Question 8

What is the normal respiratory minute volume (RMV) in awake dogs and cats?

Answer 8

approximately 200 mL/kg/minute

Question 9

What adverse effects are produced by hypercarbia?

Answer 9

• respiratory acidosis
• decreased vascular tone and cardiac function
• narcosis
• increaed ICP
• cardiac arrhythmias
• hypoxemia
• cardiac arrest

Question 10

What are the main differentials for hyperventilation during anesthesia?

Answer 10

• inadequate anesthetic depth
• elevated body temperature
• hypoxemia

Question 11

What drug may be administered to patients with malignant hyperthermia?

Answer 11

Drantolene IV 1-10 mg/kg

alters intracellular calcium kinetics
at-risk patients should be treated with drantolene orally prior to elective surgery

Question 12

What are the main differntials for a drop in ETCO2 with no change in RR or tidal volume?

Answer 12

• decrease in CO and tissue perfusion (e.g., hemorrhage, arrhythmias)
• decreaed metabolic rate (e.g., hypothermia)

Question 13

What are the ideal ranges for MAP, SAP, DAP during anesthesia?

Answer 13

MAP 70-100
SAP 100-140
DAP 40-65

Question 14

What organ is mostly at risk with a DAP < 40 mm Hg?

Answer 14

DAP < 40 mm Hg may result in poor coronary artery perfusion
the heart is only perfused durign diastole

Question 15

Direct arterial catheters for use during anesthesia may be placed in…?

Answer 15

• metatarsal arteries
• caudal artery
• auricular arteries
• femoral arteries

Question 16

anemia should not affect the pulse oximeter reading unless < ____ ?

Answer 16

< 10 %

Question 17

What is the expected CVP range in an anesthetized patient

in cm H2O and mmHg

Answer 17

0-10 cm H2O
0-7 mm Hg

Question 18

during what phase of the respiratory cycle should you measure CVP in a patient undergoing positive pressure ventilation?

Answer 18

during the expiration

inspiration will raise CVP