Vet 135 Chapter 5

Front 1

apnea monitor

Back 1

a monitor used to alert the anesthetist when the patient has not taken a breath within a set period of time. it detects a change in the temperature of the air moving between the endotracheal tube and the breathing circuit as the patient breathes

Front 2

atelectasis

Back 2

collapse of a portion or all of one or both lungs

Front 3

blood gas analysis

Back 3

measurement of the pH, bicarbonate level, and partial pressure of oxygen and carbon dioxide in the blood

Front 4

blood pressure

Back 4

the force exerted by flowing blood on vessel walls

Front 5

calculated oxygen content

Back 5

the total volume of oxygen in the blood including both dissolved and bound forms (ml/dl). CaO2 = calculated oxygen content in arterial blood. Arterial oxygen content is calculated using: CaO2 = (Hb x 1.30 x SaO2/100) + (PaO2 x 0.003)

Hb =hemoglobin grams/dl

SaO2 = oxygen saturation

PaO2 = partial pressure of oxygen

Front 6

capnogram

Back 6

the graphic representation of CO2 levels generated by a capnograph

Front 7

capnograph

Back 7

(end-tidal CO2 monitor)

a device that measures the amount of CO2 in the air that is breathed in and out by the patient by sampling air passing between the ET tube connector and the breathing circuit

Front 8

cardiac arrhythmia

Back 8

any pattern of cardiac electrical activity that differs from that of the healthy awake animal

Front 9

central venous pressure

Back 9

the blood pressure in a large central vein, used to assess blood return to the heart and heart function

Front 10

diastolic blood pressure

Back 10

arterial blood pressure when the heart is in its resting phase between contractions

Front 11

Doppler blood flow detector

Back 11

a monitoring device that uses ultrasound frequency to convert the motion of red blood cells in small arteries into an audible whooshing sound. used to monitor pulse rate and systolic blood pressure when used with a sphygomanometer

Front 12

esophageal stethoscope

Back 12

a monitoring device used to detect and amplify heart sounds via a catheter placed in the esophagus

Front 13

flaccid

Back 13

lacking muscle tone

Front 14

icterus

Back 14

yellow discoloration of the skin and mm

Front 15

mean arterial pressure (MAP)

Back 15

the average arterial blood pressure = diastolic pressure + 1/3 (systolic pressure - diastolic pressure)

Front 16

oscillometer

Back 16

a monitoring device used to measure systolic, mean, and diastolic blood pressure by detecting and analyzing pulsations of blood in the arteries of an extremity

Front 17

partial pressure of oxygen (PO2)

Back 17

a measurement of the unbound O2 molecules dissolved in the plasma expressed mmHg

PaO2 = PO2 in arterial blood

PvO2 = PO2 in venous blood

Front 18

percent oxygen saturation (SO2)

Back 18

a measurement of the percentage of the total hemoglobin binding sites occupied by oxygen molecules

SaO2= SO2 in arterial blood

SvOo2= SO2 in venous blood

SpO2 = SO2 measured by a pulse oximeter

StO2 = SO2 in tissues

Front 19

pressure transducer

Back 19

an instrument designed to measure fluid pressure that converts the pressure wave form into an electrical signal

Front 20

pulmonary thromboembolism

Back 20

the presence of one or more blood clots in the lung

Front 21

pulse oximeter

Back 21

a monitoring device used to estimate the percent oxygen saturation of hemoglobin by measuring subtle differences in light absorptions and the pulse rate by detecting blood pulsations in the small arterioles

Front 22

respiration

Back 22

the process by which oxygen is supplied to and used by the tissues, and carbon dioxide is eliminated from the tissues

Front 23

respirometer

Back 23

a monitoring device used to measure the tidal volume and respiratory minute volume

Front 24

sphygomanometer

Back 24

a monitoring deice consisting of a pressure gauge and cuff used to measure arterial blood pressure

Front 25

systolic blood pressure

Back 25

arterial blood pressure during contraction of the ventricles

Front 26

tachypnea

Back 26

rapid respiratory rate

Front 27

ventilation

Back 27

the movement of gases into and out of the alveoli

Front 28

monitor

Back 28

latin monere "to warn"

Front 29

reflex

Back 29

involuntary response to a stimulus

Front 30

Normal cattle vitals during anesthesia

Back 30

HR: 50-80 report if less than 40 or greater than 100

Heart rhythm: NSA or SA

RR: 6-12, rapid shallow breathing common, report if less than 6 or greater than 20

Temperature: 97-100 report if less than 97 or greater than 103.5

Front 31

Normal Dog Vital signs during anesthesia

Back 31

HR: 60-150bpm report if less than 60 or greater than 140 (large) and less than 70 or greater than 160 (small)

Heart rhythm: NSR or SA

RR: 8-20 report if less than 6 or greater than 20

Temperature: 97-100 report if less than 97 or greater than 103.5

MAP: >60

Front 32

Normal Cat vital signs during anesthesia

Back 32

HR: 120-180 report if less than 100 or greater than 200

Heart rhythm: NSR

RR: 8-20 report if less than 6 or greater than 20

Temperature: 97-100 report if less than 97 or greater than 103.5

MAP: >60

Front 33

Normal Horse vitals during anesthesia

Back 33

HR: 28-40 report if less than 25 or greater than 60

Heart rhythm: NSR, SA or first or second degree AV heart block

RR: 6-12 report if less than 6 or greater than 20

Temperature: 97-100 report if less than 97 or greater than 101.5

MAP: >70

Front 34

Normal PR intervals

Back 34

Dog: 0.6 - 0.13 seconds

Cat: 0.05 - 0.09 seconds

Horse: 0.22 - 0.56 seconds

Front 35

Sinus arrhythmia

Back 35

HR decreases during expiration and increases during inspiration

Front 36

Sinus tachycardia

Back 36

abnormally fast HR, may be caused by inadequate anesthetic depth, drug reactions, and surgical stimulation

Front 37

Sinus bradycardia

Back 37

abnormally slow HR, may be caused by drug reactions or excessive anesthetic depth

Front 38

AV heart block

Back 38

delay in conduction of the electrical impulse through the AV node

First degree: prolonged PR interval, may be caused by alpha2 agonists (dexdomitor)

Second degree: occasional missing QRS complexes, may be caused by administration of alpha2 agonists (dexdomitor), high vagal tone, hyperkalemia, and cardiac disease

Third degree: atrial and ventricular contractions occur independently, decreases cardiac output

Front 39

Premature Complexes

Back 39

Supraventricular premature complexes (SPCs): appear as one or more normal QRS complexes that closely follow the previous QRS complex interrupting an otherwise normal rhythm, p waves may or may not be seen.

Supraventricular tachycardia: a series of three or more SPCs in a row

Ventricular premature complexes (VPCs): one or more wide, bizarre QRS complexes. Isolated VPCs commonly seen in anesthetized animals, can be caused by heart disease, drugs, hypoxia, and acid-base or electrolyte disorders, epinephrine release in fearful animals especially in patients given arrhytomogenic agents.

Ventricular tachycardia: a series of three or more VPCs in a row, significantly compromises cardiac output. IV lidocaine is most common treatment

Front 40

Fibrillation

Back 40

chaotic, uncoordinated contraction of small muscle bundles within the atria or ventricles that appears as an undulating baseline with or without QRS complexes

-Atrial fibrillation: fine undulations of the baseline, an abscense of p waves, a high HR and normal QRS complexes with irregular intervals between them.

-Ventricular fibrillation: irregular undulating baseline with complete absence of recognizable QRS complexes, associated with cardiac arrest

Front 41

stroke volume

Back 41

the volume of blood ejected by the heart on each beat

Front 42

vascular resistance

Back 42

the diameter of the vessels

Front 43

Common causes of hypotension

Back 43

-anesthetic agents (ace, alpha2 agonists, barbiturates, propofol, inhalant gases)

-excessive anesthetic depth

-vasodilation secondary to allergic reactions or endotoxic shock

-blood loss

-dehydration

-cardiac arrhythmias

-preexisting heart disease

-positive pressure ventilation

-gastric distention

Front 44

Mean arterial pressure (MAP)

Back 44

average pressure through the cardiac cycle, best indicator of perfusion

=diastolic pressure + 1/3(systolic pressure - diastolic pressure)

Front 45

Chapter 5 notes

Back 45

-anesthetist must observe vital signs, reflexes, and other indicators of anesthetic depth

-vital signs are variables that indicate the response of an animals homeostatic mechanisms to anesthesia (HR, heart rhythm, RR and depth, mm color, CRT, pulse strength, BP, temperature. These indicate how well the patient is maintaining basic circulatory and respiratory function under anesthesia. They are not reliable indicators of anesthetic depth.

- reflexes used: palpebral, corneal, pedal, swallowing, laryngeal, PLRs

-other indicators include: spontaneous movement, eye position, pupil size, muscle tone, nystagmus, salivary and lacrimal secretions, and response to surgical stimulation

-P1 and P2 patients should be monitored at least once every 5 minutes.

-P3, P4, and P5 patients should be monitored continuously

-loss of spontaneous muscle movement marks the border between stage two and three

-loss of consciousness marks the border between stage one and two

-Stage 1(period of voluntary movement): patient begins to lose consciousness, characterized by fear, excitement, disorientation, struggling, HR and RR increase, typically in this stage patients are hard to handle, near the end of the stage, the patient loses the ability to stand and becomes recumbent

-Stage 2 (period of involuntary movement): patient loses voluntary control, breathing becomes irregular, vocalizing, struggling, paddling, HR and RR are often elevated, pupils dilate, muscle tone is marked, reflexes are present. Stage ends when the patient shows signs of muscle relaxation, slower RR, and decreased reflex activity. Potentially hazardous stage, risk of epinephrine release and potential for cardiac arrhythmias and arrest. This stage is very pronounced with mask or chamber induction

-Stage 3 (period of surgical anesthesia):

Plane 1: respiratory pattern becomes regular and involuntary limb movements cease, eyeballs start to rotate ventrally, pupils may become partially constricted and pupillary response to bright light is diminished, gagging and swallowing reflexes are depressed allowing intubation, pedal and palpebral reflexes still present. Patient will not tolerate surgical procedures and will move and exhibit increased HR, RR and depth and BP in response to pain.

Plane 2: suitable for most surgical procedures, stimulation may cause a mild increase in HR or RR but patient remains immobile. PLRs are sluggish and pupil size is moderate, respirations are regular but shallow, RR, HR, and BP are mildly decreased. Muscle tone is more relaxed, pedal and swallowing reflexes are absent, laryngeal and palpebral reflexes are diminished or lost, ventromedial eye rotation. Loss of pedal and swallowing reflexes mark entry into plane 2.

Plane 3: significant depression of circulation and respiration often present, considered excessively deep for most procedures, HR and RR are low and tidal volume is decreased, manual or mechanical ventilation may be necessary, HR remains decreased even in the presence of sx stimulation, pulse strength may be reduced due to a fall in BP, CRT may increase from 1.5 to 2 seconds, PLR is poor and maybe absent, eyes are often central and with moderately dilated pupils, reflexes are totally absent, muscles are so relaxed that there is no resistance to opening the mouth.

Plane 4: period of early anesthetic overdose, abdominal breathing, fully dilated pupils, absence of all reflexes, flaccid, cardiovascular system is markedly depressed with a dramatic drop in HR and BP, pale MM, prolonged CRT

-Stage 4 (stage of anesthetic overdose): cessation of respiration, which may be followed by circulatory collapse and death

-objectives of surgical anesthesia are that the patient does not move, is not aware, does not feel pain, and has no memory of the procedure

-lack of unconscious movement is evidence of sufficient depth

-Indicators of Circulation:

1. heart rate: may be determined through palpation of the apical pulse through the thoracic wall or of a peripheral pulse or auscultation with a stethoscope or mechanically with an electrocardiograph, bp monitor. Heart is harder to hear with a stethoscope during anesthesia because of decreased contraction strength and gravity. Alpha2 agonists (dexdomitor, xylazine, dormosedan) and opioids (torb, buprenex, tramadol) likely to cause bradycardia as well as excessive anesthetic depth. Tachycardia is caused by inadequate depth, pain during light surgical anesthesia, hypotension, blood loss, shock, hypoxemia, and hypercapnia

-arrhythmias are commonly caused by anticholinergics, alpha2 agonists, barbiturates, and cyclohexamines, but can also be caused by certain disease states, hypoxia, hypercarbia, heart disease, trauma, and GDV

-esophageal stethoscopes are lubricated and inserted into the esophagus to the level of about the fifth rib or scapula

-ECG: wave of electrical activity starts at the sinoatrial node travels through the intermodal tracts causing contraction, it is then conducted to the atrioventricular node where is slows down to allow the ventricles to fill with blood, then travels to the ventricles through the bundle of his, bundle branches, and purkinje fibers, causing ventricular contraction

-P wave represents contraction of the atria

-PR interval separates the p wave from the qrs complex and represents the time required for the impulse to move from the sinoatrial node to the purkinje fibers

-QRS complex represents contraction of the ventricles

-T wave represents repolarization of the ventricles, usually no more than one-fourth the size of the QRS complex

-A change in the configuration of the QRS complex or T wave over time indicates hypoxia of the cardiac muscle

-prolonged CRT >2 seconds indicates reduced perfusion in the tissue tested, can be due to vasoconstriction from epinephrine release, low BP caused by anesthetic drugs(ace, propofol, alpha2 agonists, inhalents), hypothermia, cardiac failure, excessive anesthetic depth, blood loss or shock

-blood pressure is used to assess tissue perfusion under anesthesia, it is determined by interactions among the HR, stroke volume, vascular resistance, arterial elasticity, and blood volume so it will be altered by anything affecting these factors (drugs, disease, surgical stimulation, hydration status)

-BP should be monitored in trends

-If MAP falls below 60mmHg blood flow to internal organs is reduced and tissues become hypoxic, kidneys are very sensitived to reduced MAP and can fail postoperatively if MAP is inadequate during anesthesia.

-Doppler BP monitors can underestimate cat systolic pressure by about 15mmHg

-Using BP cuffs that are too narrow will give falsely high readings and cuffs that are to wide will give falsely low readings. The cuff width should be 30% - 50% of the circumference of the patient's leg.

-Oscillometric BP machines tend to underestimate high bp and overestimate low bp, relatively accurate in patients over 7kg, but have difficulty in small dogs and cats, are inaccurate in patients with significant hypotension, arrhythmias, or fast HRs.

--Indicators of oxygenation:

-MM: normal is bubblegum pink

-pale MM indicate intraoperative blood loss, anemia, poor capillary perfusion (vasoconstriction, excessive anesthetic depth, or prolonged anesthesia)

-Cyanosis indicates very low blood oxygen concentration in patients with normal PCV, there must be a minimum concentration of hemoglobin for cyanosis to occur therefore patients who are anemic may not have enough hemoglobin to reach the threshold and my not turn blue even though tissues are hypoxic.

-total oxygen content of blood is carried either unbound dissolved in plasma or chemically bound to hemoglobin.

-each hemoglobin molecule can bind four oxygen molecules

-bound oxygen represents the majority of the oxygen concentration of an animal

-the Pao2 and Spo2 do not give accurate measures of oxygen availability in anemic patients.

-Spo2 should be greater than 95% during oxygen administration

-Spo2 reading of 90%-95% indicates hypoxemia and requires investigation

-Spo2 reading less than 90% indicates a need for therapy and a reading less than 85% for longer thank 30 seconds constitutes and emergency

--Indicators of Ventilation:

-Tidal volume is the amount of air inhaled with a breath, normal tidal volume = 10-15ml/kg but decreases by about 25% in anesthetized animals

-CO2 of 35 -45 mmHg is considered normal in the non-anesthetized patient

-reflexes:

-swallowing reflex: lost during medium surgical anesthesia, returns during recovery just before patient regains consciousness.

-palpebral reflex: lost during medium surgical anesthesia, presence of this reflex while on gas anesthesia indicates patient is too light

-pedal reflex: flexion or withdrawal of a limb in response to vigorous squeezing, twisting or pinching of a digit or pad. Lost during surgical anesthesia.

-PLR: should be present in light and medium surgical anesthesia.

-Eyes: central during light anesthesia, ventromedial during medium anesthesia, and central during deep anesthesia

-Pupils: dilated during stage II anesthesia, normal or constricted during light surgical anesthesia, progressively dilate as anesthetic depth increases and are widely dilated during deep anesthesia.