monitoring with instrumentation

MONITORING ANIMALS WITH THE USE OF INSTRUMENTATION

These machines can be very useful, especially in the situations where the

technician can’t always be with the patient through the entire procedure; however

you should never completely rely on your machines

The following can be monitored via machines: Blood pressure, Central Venous

Pressure, Blood Gases, Pulse Oximetry, Capnography, and Electrocardiography

◦ Measures the electrical activity of the heart – NOT the mechanical activity. REMEMBER THAT THE EKG CAN CONTINUE EVEN

IF YOUR PATIENT’S HEART IS NOT CONTRACTING. This is called ________________________________________

◦ The complexes should be of normal configuration, consistent size, rate, and rhythm

◦ If the complexes look abnormal: Alert the Dr. Check the patient! Check the lead placement

A cardiac arrhythmia is any pattern of electrical activity that differs from the

healthy, awake animal

MOST COMMON EKG ABNORMALITIES SEEN WHICH MUST BE ADDRESSED are:

1) ________________________________◦ Diagnosed when a patient’s HR under anesthesia

is: >200 bpm in cat>180 bpm in small dog> 160 bpm in large dog

◦Causes: Can be _________________ (atropine, ketamine),

or response to surgical stimulation If animal is “huffing” during surgery if reflex activity is present or moving occurs, patient may

be too “light”

Can also occur in situations of ________________, ______________________, or high ______________ levels

Pre-existing conditions of the heart, thyroid, anemia, shock (compensatory/early)

◦Treatment: Emergency treatment can include applying

pressure to the eyeballs

2) _______________________________◦ Diagnosed when patient’s HR under anesthesia is:< 60 bpm in large dog<70 bpm in small dog< 100 bpm in a cat

◦Causes: Can be drug related (xylazine, dexmedetomidine,

opioids) Increased anesthetic depth, hypoxia (late stages),

hypothermia

◦Treatment: Can give reversal agents or atropine Assess other parameters before deciding management

3) ________________________◦ Electrical impulse through the heart is not being

transmitted efficiently.

_______________________: There is a P wave for every QRS complex, but the P-QRS interval is prolonged

_______________________: Some P waves are not followed by QRS complexes

_______________________: The atria and ventricles are contracting independently. No normal relationship between P waves and QRS complexes

2nd and 3rd degree blocks can be seen after alpha-2-agonist administration & high vagal tone

4) _________________________________◦ Impulse arising from the ventricular muscle

causing an uncoordinated heart contraction◦ QRS complexes are wide and bizarre◦ Causes:

hypoxia, heart disease or trauma, electrolyte abnormalities, etc

Epinephrine release can stimulate the formation of VPCs Don’t forcibly restrain an animal during the induction of

anesthesia!

5) ______________________: > 3 VPCs in a row, more than 15 in one minute, or VPCs + falling blood pressure

EMERGENCY!! Can be treated with __________________given IV

6) ________________________◦ Contraction of small muscle bundles within the

atria or ventricles Atrial fibrillation

No p-waves, high HR, normal QRS complexes

Ventricular fibrillation Absence of QRS complexes CARDIAC ARREST IS IMMINENT

ECG: Atrial Fibrillation

Refers to arterial blood pressure _______________________Pressure – produced by

the contraction of the ventricles as it propels blood through the aorta, pulmonary artery, and other major arteries

______________________ Pressure – the pressure that remains when the heart is resting between contractions.

_______________________(MAP) - average pressure through the cardiac cycle and best indicator of organ perfusion under anesthesia

= diastolic pressure + (systolic-diastolic pressures) 3

Pulse pressure – pressure detected by manual palpation◦ the difference between systolic and

diastolic pressure

Blood pressure can vary with age, breed, species, and instrumentation

It is important to monitor TRENDS in blood pressure in addition to actual values

BLOOD BLOOD PRESSUREPRESSURE

Normal systolic BP in awake dogs and cats:120◦ Normal range: 90-150 mm Hg◦ Should ideally remain at or above _______mm Hg in anesthetized

patients

Normal diastolic BP in awake dogs and cats: 80 ◦ Normal range: 50-90 mm Hg

Normal MAP: 90-100 mm Hg ◦ Should be maintained above ________mm Hg in anesthetized

patients◦ This is the best indicator of blood perfusion to the internal

organs

BLOOD PRESSUREBLOOD PRESSURE

INDIRECT BP MONITORING◦ Method most commonly used in private practice◦ Noninvasive, less technically difficult than direct

monitoring

2 types of INDIRECT BP monitors: ______________________

Measures systolic, diastolic, MAP _____________________

Measures systolic only

INDIRECT BP MONITOR: OSCILLOMETRICINDIRECT BP MONITOR: OSCILLOMETRIC

determines, systolic, diastolic, and MAP by detecting the oscillations within the cuff caused by the pulsation of the artery beneath the cuff

Less labor intensive than Doppler monitors but tend to be less consistent in their ability to register blood pressures for smaller patients

The machine can be set to automatically take a BP measurement every 2 to 3 minutes-1 minute cycles tend to create an ischemic

challenge to the extremity

Cuff width should be _______________of limb circumference for dogs and cats

Excessively ___________cuffs will lead to an under-estimation of blood pressure

Excessively ___________ cuffs will lead to an over-estimation of blood pressure

Location of cuff is important Most consistent cuff location for small patients is the

________________, other: tail base, distal tibia Don’t hesitate to try all locations as needed Good locations for larger animals include

metacarpus, metatarsus, and distal tibia just above tarsus

-More consistently effective when monitoring small patients

-Measures systolic pressure only

-Hair is clipped at the probe site-The depression in the probe must be filled with ultrasound gel-place the probe over the metacarpal or metatarsal artery-Once you hear the swishing sound of the heart beat, tape the probe in

place-Both excessive and inadequate pressure can create difficulties

measuring accurately

◦Cuff width is as important with doppler BP measurement as with oscillometric BP measurement

Cuff width should be 30-50% of limb circumference for dogs

Excessively wide cuffs will lead to an underestimation of blood pressure

Excessively narrow cuffs will lead to an overestimation of blood pressure

◦ 5 readings are taken, the highest and lowest are thrown out. The average of the other 3 are used to determine the SAP.

http://www.youtube.com/watch?v=Li4oGhfKmDQ

http://www.vasg.org/

doppler_use.htm

Used less than indirect methods in private practice◦ Indwelling catheter is placed in ___________

or ______________________artery◦ Catheter is connected to a manometer or

pressure transducer via a fluid-filled tubing and the pressure is displayed

http://www.vasg.org/direct_arterial_pressures.htm

◦ Check the patient!

◦ _______________________ the inhalant anesthetic setting

◦ ____________________the IV fluid flow rate

◦ ____________________ to ensure proper placement/size

◦ Finally…. Hetastarch, Dopamine, Dobutamine ….to be used in emergencies!

Measurement of the blood pressure in a central vein: ______________________

Assesses how well the blood is returning to the heart and the ability of the heart to receive and pump blood◦ Helpful in monitoring animals with right sided

heart failure and preventing over-hydration in animals receiving IV fluids

www.dcavm.org/08techmar.html

http://books.google.com/books?id=LtGS0t1MIskC&pg=PA410&lpg=PA410&dq=manometer+veterinary+medicine&source=web&ots=BIOCQL_14Z&sig=MZnEtUSN6vpdi4TTnNjYkAduva4&hl=en&sa=X&oi=book_result&resnum=9&ct=result#PPA410,M1

Refers to measurement of ____________ by measuring dissolved oxygen and carbon dioxide gas in arterial blood.

Indicate how well the patient is obtaining oxygen and delivering it to the tissues and how well the lungs are expelling carbon dioxide◦ All of these depend on the respiratory

function of the patient.

OXYGEN EXISTS IN 2 FORMS IN THE BLOOD: 1) Free molecule dissolved in plasma (PO2 or

PaO2)Measured by a blood gas analyzerValues below 60 mm Hg indicate hypoxia!!

2) Chemically combined with hemoglobin in RBCs (SO2 or SpO2)Measured by a _____________________

Not commonly used in private practice Blood sample should be taken from an artery

Sample is placed on ice and should be run within 2 hours of collection

Inexpensive, noninvasive, portable, easy to use

Clip is placed on a thin strip of tissue that is nonpigmented and hairless◦ Most commonly the _____________, but can also

use the pinna, rectal mucosa, toe webbing, lip, vulvar fold, Achilles tendon, under base of tail

Values should read _________% or greater under anesthesia

◦ Values between _______________% indicate hypoxemia

◦ Values less than 90% indicate a need for therapy Treatment: assisted ventilation, supplement oxygen

◦ Values less than ______% for greater than 30 sec. is a medical emergency

PaCO2 : The portion of carbon dioxide that is dissolved in plasma (Carbon dioxide partial pressure in the arteries)◦ Measured using a blood gas analyzer

◦ An awake patient’s levels are usually less than 45 mm Hg. It is common to see levels of ____________mm Hg in an anesthetized patient because the animal doesn’t breathe deeply enough to eliminate the usual amount of CO2

◦ If greater than 60 mm Hg, hypoventilation is present. Assess other parameters to determine oxygenation and assist ventilation if necessary

Carbon dioxide build-up can result in respiratory __________________◦ Commonly seen levels are 7.2-7.3 as compared to

normal values of 7.35-7.45◦ Blood pH is measured via blood gas analyzers

A ___________________ is placed on the endotracheal tube: it monitors the amount of CO2 that is expired

Noninvasive◦ Info is displayed as a graph

Measures ______________________ As inspiration occurs, CO2 should be around

__________ Hypercapnea: ET CO2 greater than ________mm Hg

◦ Causes: CO2 canister needs changing, hypoventilation (should correct when patient is bagged)

Hypocapnea = ET CO2 less than 35 mm Hg◦ Tachypnea, dead space, too much assisted

ventilation, improper endotracheal tube placement/connection

◦ The main reason for a low SpO2 in an anesthetized patient is decreased ventilation

1) The animal is not breathing well and you need to assist it Respiratory rate should be 8 – 20 breaths /min

for the average patient (avg = 10-12 bpm). Small patient may need more breaths.

Try just occasional breaths at first

2) The patient has _________________________– the oxygen isn’t getting to the areas in the lungs where the blood is Check that the machine is hooked up properly Check that the oxygen is turned on/in tank Check that the endotracheal tube is placed correctly

and the cuff is properly inflated. If the tube is in too far, the gas/O2 will only go to one side of the lungs.

3)  The patient’s pulse is weak Check that the patient isn’t too deep Check the blood pressure and act accordingly

(see section on blood pressure)

 4)  The sensor is slipping off the patient

5)   The sensor has been at one location for a long time and is too dry or is pinching off blood supply to the area. The following locations may be used for the pulse ox. probe: tongue, lips, ear, toe webbing, prepuce, and vulva.