Patient Monitoring During Anesthesia Flashcards by Kate Guiremand

what is the motto of anesthesia

Vigilance!!

expresses the need for quick recognition of a problem

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why monitor?

provide better patient care (early Dx and Tx)

prevent mortality and morbidity

protect the anesthetist (records!)

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how often should you monitor?

ideally a responsible person is always available

monitor and record the results every 5 minutes

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what 4 main things should be monitored

circulation

oxygenation

ventilation

temperature

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common methods for monitoring circulation

mucous membrane color, CRT

palpation of pulse

ascultation of heart beat

ECG

blood pressure - recommended for all patients

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when palpating the pulse, assess:

rate, rhythm and quality

subjective measure of adequacy of CO

NOT a surrogate for BP

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T/F pulses at different sites may feel different

True

varible soft tissue coverage

variable distance from the heart

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which artery is affected earlier by hypotension and low CO?

Distal artery/dorsal metatarsal

if it feels strong than it likely indicates good CO

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common pulse palpation sites in small animals

labial

digital

dorsal pedal

metatarasal

femoral

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pulse palpation sites in large animal

auricular

transverse facial

facial

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ausculation of the heart assess:

heart sounds, rate and rhythm

respiratory sounds and rate

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T/F the ECG does not indicate that the heart is contracting

True!

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clinical uses of ECGs

determine heart rate and rhythm

aid in Dx and Tx of electrolyte disturbances (Hyperkalemia)

Dx chamber enlargement

may provide clues about myocardial oxygenationa dn perfusion abnormalities and location of certain cardiac disease

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Mammalian type A conduction system

small animals

purkinjie fibers excite the endocardium only

base to apex current flow

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Mammalian type B conduction system

horses, ruminants, pigs

purkinje fibers penetrate the myocardium

apex to base current flow

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which lead is preferred in small animals

lead II

yeilds tallest R-wave

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which lead is perferred in large animals

lead I

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T/F you may need to be creative with ECG lead placement

True

surgical prepartation may prevent standard electrode placement

ECG traces that look normal will suffice for anesthesia

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T/F ECG gel or saline can be used for elextrode contact but not alcohol

True

alcohol may ignite if patient had to be defibrillated, poor conductor of electricity

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what is the most clinically relevant information gained from the ECG

heart rate

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T/F normal HR and strong pulse indicates adequate cardiac output even if not sinus rhythm

True

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what is the best way to dertermine HR

count yourself while looking at watch

asculate, palpate pulse, listen to doppler

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what can effect HR/PR given by the ECG and pulse oximeter

bad signal quality

double counting

uneven HR (signal is averaged over time)

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what are common arrhythmias under anesthesia

sinus bradycardia and tachycardia AV blocks (1st and 2nd degree)

what can prevent/ reduce runs of V-tach while under anesthesia

phenoxybenzamine pretreatment

what happens to blood pressure when HR is high

plummets

when should you treat ventricular arrythmias under anesthesia

if there is severe underlying heart disease risk of sudden death

when might you consider treating ventricular arrhythmias

severe systemic disease

if a patient has ventricular arrhythmia with moderate systemic disease or trauma should you treat the arrhythmia

only if it affects hemodynamics

what is the first line of Tx for ventricular arrhythmias

Lidocaine IV

what does blood pressure monitoring depend on

where and how it is measured

how does the BP signal change as move from central to periphery

systolic becomes higher diastolic becomes lower mean remains similar

systolic pressure on the BP waveform

highest point of BP curve represents afterload for the left ventricle

mean pressure on the BP waveform

aver BP over a full cycle determinant of tissue perfusion

diastolic pressure on BP waveform

lowest point of the BP curve determinant of mycoardial perfusion

mean and systolic that indicate hypotension in small animals

**Mean:** \<60 **Systolic:** \<80

mean and systolic that indicate hypotension in large animals

**Mean:** \<70 **Systolic:** \<90

how should you treat hypotension under anesthesia

decrease anesthetic administration give fluid bolus give drugs (inotropes or vasocontrictors)

what other things does a BP measurement yeild

heart rate BP changes with respiration: indicate hypovolemia waveform: info about inotropy, CO and effect of arrhythmias

how can BP be calculated

**BP= (HR x SV) x SVR** SV: depends on the preload and contractility; preload depends on circulating volume CO=HR x SV

what are the 4 crucial elements of CV function

HR (and rhythm) contractility Circulating volume Vasconstriction \*\*these elements must be **normal**, not maximal\*\*

what is the gold standard for measung BP

Invasive (direct): continuously via arterial catheter

what are the most common types of non-invasive (indirect) BP measurement

oscillometric and doppler intermittently use a pressure cuff

how do you measure IBP

insert catheter into an artery connect to saline filled rigid tubing connect transducer to a monitor ensure that blood does not clot in the catheter (flush it)

IBP shoudl be used in horses if they are anesthetized for longer than:

45 min

which arteries can be used for IBP in a dog

dorsal pedal, metatarsal

which arteries can be used for IBP in a cat

dorsal pedal, coccygeal

which arteries can be used for IBP in a horse

facia, transverse facial, digital

which arteries can be used for IBP in a cattle

auricular

which arteries can be used for IBP in sheep and goats

median

where should the BP transducer be positioned

point of the shoulder in dorsal recumbency point od sternum in lateral recumbency

what is oscillometric NIBP

arterial blood flowing under an inflated cuff generates pressure flucuations in the cuff that is detected by the monitor

what is doppler NIBP

an inflated cuff is placed over an artery blood flow is detected distally from the cuff using a Doppler flow probe after complete occulsion of lfow, cuff pressure is slowly decreased pressure where blood flow reappears is systolic BP

how wide should the BP cuff be

40% of the circumference of the limb

cuff placement in small animals

distal radius distal tibia metatarsus

cuff placement in large animals

metacarpus, tail

what is an advantage of oscillometry

provides systemolic, mean and diastolic BP

what is the main disadvantge to oscillometry

if patient arrest in between readings you may not know

if you can only afford a single anesthesia monitor you should choose:

a doppler

how is oxygenation measured

by pulse oximeter or blood gas

what is hypoxemia

reduction of oxygenation of arterial blood (reduction of PaO2, SaO2 or Hb content)

a patient is considered hypoxemic when

PaO2 \< 60 mmHg SaO2 \< 90%

PaO2 and SaO2 should always be interpreted in light of:

inspired O2 fraction (FiO2)

a healthy air breathing animal should have a SaO2 of

\>95%

what should SaO2 be if the animal is breathing pure O2

\>98%

what can affect the results of a pulse oximeter

hypoperfusion pigmentation movement abnormal Hb - CO poisoning, methemoglobinemia

when is it important to use a pulse oximeter

patient is breathing room air there is V/Q mismatch there is respiratory disease

what is ventilation defined by

PaCO2 process involved in the movement of air (gas) in and out of the alveoli

what is the normal range for PaCO2

35-45 mmHg

PaCO2 values \>45 can be caused by

hypercapnia or hypoventilation

PaCO2 values \<35 can be caused by

hypocapnea or hyperventilation

T/F tachypnea does not equal hyperventilation

**True** there is no reliable correlation between respiratory pattern and PaCO2

a capnometer measures

only ET CO2

what does a capnograph measure

ET CO2 vs time on a graph continuous

T/F a capnogram can be an indirect assessment of CO

**True** especially during CPR - adequate CO is necessary for the transport of CO2 from the tissues to the alveoli

what factors influence ET CO2 values

CO2 production circulation alveolar ventilation measurement error

what is phase I indicative of

baseline (inspiration)

What is phase II indicative of

Expiratory upstroke

what is phase III indicative of

alveolar plateau

what is phase IV indicative of

inspiration begins

what measurement is indicated by the red arrow (D)

ET CO2

what pattern is seen here

hyperventilation

what pattern is seen here

hypoventilation

what pattern is seen here

CO2 rebreathing

what pattern is seen here

spontaneous breathing during mechanical ventilation

what pattern is seen here

progressive airway obstruction

what pattern is seen here

cardiogenic oscillations

what pattern is seen here

cardiac arrest

what can be seen with hypothermia (\<96º)

decrease in the MAC of the anesthetics (less ISO needed) CV system may be depressed (bradycardia) recovery may be prolonged

T/F hyperthermia is less common but more serrous than hypothermia

**True** \>102ºF, may damage the CNS

how can core body temp be measured

esophageal temperature probe entered into mid thorax

peripheral body temperature is

colder than core temp pharyngeal, nasal, rectal

Tx for hyperthermia

find the cause **COOL!!** - switch off heatng devices/blankets, decrease room temp, ice packs, ice cold infusions etc

T/F anesthetic depth should be determined without reguard to body temp

**True** it would be misconduct to increase vaporizer dial setting as a "treatment" for hyperthermia

what is included in the anesthesia record

drug administration (dose, time, route) monitored variables (HR, RR,) - min every 5 min

T/F it is ideal to have personnel that are fully and continuously dedicated for anesthesia care

**True**

normal limits under GA

check out this super amazing chart!!