L9: Monitoring during Anesthesia (Tenenbaum)

Question 1

what systems are monitored at minimum?

Answer 1

CNS
CVS
Respiratory
Renal
(temp)

Question 2

signs to look for when assessing whether patient is in good plane of anesthesia***

Answer 2

position of eye
movement
m. tone
certain reflexes
response to surgical stimulation
nystagmus (esp. in horse)
shivering
eye reflexes present

Question 3

signs of LIGHT plane of anesthesia

Answer 3

• central eye position
• cessation of limb movements
• m. tone remains
• response to sx stimulation
• nystagmus
• eye reflexes
• shivering
• moist cornea

Question 4

signs of MEDIUM plane of anesthesia

Answer 4

• no spontaneous movement
• no reflex movement
• no change in hemodynamic or breathing during sx stim.
• mod. m. tone
• dec. in tidal volume
• no palpebral reflex
• no shivering
• ventromedial rotation of eye
• small pupil aperture
• moist corneas

Question 5

signs of DEEP plane of anesthesia

Answer 5

• dec. in Vt
• abd. breathing
• eyes fixed centrally
• no reflexes
• bradycardia/hypotension and worsening of hemodynamic fx
• dilated pupil
• dry cornea

Question 6

causes of white/pale mm

Answer 6

anemia
vasoconstriction
lack of circulating fluid

Question 7

causes of cyanotic mm

Answer 7

lung disease
dec. in oxygen flow to the breathing circuit
endobronchial intubation

Question 8

causes of red/bright pink mm

Answer 8

hypercapnia

Question 9

common arrhythmias

Answer 9

sinus tachycardia
sinus bradycardia
2nd degree AV block
VPCs

Question 10

ECG:

Answer 10

• good for detecting HR and rhythm but not in evaluating cardiac fx and heart disease
• each patient is different!**
• N dog: 70-140
• N cat: 110-140
• N horse: 30-45

Question 11

mean BP should be maintained above:

Answer 11

60mmHg (70 in horses)

Question 12

direct BP measurement

Answer 12

• arterial catheter connected to pressure transducer
• provides real time beat by beat pressure monitoring
• invasive

Question 13

indirect BP measurement

Answer 13

• aka sphymomanometry
• use of pressure cuff, doppler shift pulse detectors
• if cuff to wide or tight, underestimate blood pressure
• systolic should be >80mmHg

Question 14

oscillometric method

Answer 14

• cuff inflated to a pressure and pressure is slowly released as the monitor detects the oscillations in the cuff caused by the blood flow under the cuff
• MAP >60mmHg

Question 15

how can CO be measured

Answer 15

invasive thermodilution

-not used routinely

Question 16

how is pulse oximetry measured

Answer 16

light absorption of 2 different wavelengths at fast intervals during pulsations

• detects reduced Hb and oxyHb
• % of saturated Hb is calculated
• sensitive to movement, cold, vasoconstriction
• should be >95%

Question 17

central venous pressure

Answer 17

• P within the thoracic vena cava
• balance b/w venous blood volume and contractility of the heart
• dec. CVP: hypovolemia
• inc. CVP: fluid overload

Question 18

urine output depends on

Answer 18

CO
blood volume
renal function

Question 19

normal tidal volume***

Answer 19

10-15mg/kg

Question 20

blood gas analysis

Answer 20

• measures lvls of oxygen and CO2 in arterial blood
• provides acid-base status
• can also measure electrolytes/glucose/lactate

Question 21

capnography**

Answer 21

-measures the end tidal CO2 and the inspired CO2 tension
-connected between the patient and the breathing system
-useful to measure:
hypoventilation
hyperventilation
apnea
disconnection
rebreathing
obstruction
embolism
-provides info on:
1) adequacy of ventilation
2) CV system
3) patient’s metabolism

Question 22

phases of the capnogram: phase I***

Answer 22

Inspiratory baseline

• represents the inspiration of fresh gas with CO2
• should stay at the level that corresponds to zero concentration of CO2

Question 23

phases of the capnogram: phase II***

Answer 23

Expiratory upstroke

• occurs shortly after inspiration ends
• caused by the rapid washing out of the fresh gas in the anatomic space and then replacement by CO2-rich alveolar gas
• should be steep

Question 24

phases of the capnogram: phase III***

Answer 24

Expiratory plateau

• represents continuous exhalation
• horizontal line if no V/Q mismatch, but usually CO2 slowly increases as the gas from the lung areas with lower rate of ventilation to perfusion reaches the sampling site

Question 25

phases of the capnogram: phase IV***

Answer 25

Inspiratory downstroke

• occurs shortly after expiration ends
• represents the rapid washing out of the CO2 by fresh gas as inspiration starts
• should be steep

Question 26

how is pulse oximetry an indicator of the resp. system

Answer 26

lower oxygen tension means lower arterial oxygen saturation

-will also see low saturation w/ pulmonary embolism

Question 27

anesthetic complications of hypothermia

Answer 27

• decreased anesthetic requirements
• not responding to anticholinergics
• prolonged recovery
• cardiopulmonary depression