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Define the "Maintenance Period" of general anesthesia.
between induction and recovery
What should the anesthetist check before anesthesia?
- check the patient's vital signs and reflexes
- know what the patient's "normal" is
How often should the anesthestist monitor the patient?
- every 3 - 5 minutes in routine cases
- continuously for risky patients
Describe a patient that is too light.
Describe a patient that is too deep.
- prolonged recovery
- brain damage
Explain the importance of monitoring vital signs.
- indicate patient's response to anesthesia
- "how well is the patient doing"
How are vital signs monitored?
- manual monitoring
- electronic monitoring
What kind of machines are used for electronic monitoring?
- pulse oximeter
- blood pressure monitor
What are the different types of vital signs that can be monitored?
- heart rate and rhythm
- blood pressure
- capillary refill time
- mucous membrane color
- respiratory rate
- blood gases
What is a dog's normal away heart beat?
70 - 180 bpm
What is a dog's minimum heart rate under anesthesia?
What is the normal heart rate for a cat?
110 - 200 bpm
What is the minimum heart rate for a cat under anesthesia?
100 bpm penis
Most anesthetic drugs cause _____ heart rate, except _____.
What is a sinus rhythm?
heart rate is increases on inhalation and decreases on exhalation
What animal is sinus rhythm normal in?
What is arrhythmia?
irregular heart beat
What is arrhythmia due to?
irritation of myocardium
What are the causes of arrhythmias?
- anoxia (not enough oxygen)
- hypercapnia (increase in CO2)
- certain drugs (halothane, xylazine)
How do you monitor the heart?
- feeling or hearing the heart beat, or seeing EKG of heart beating
- does not prove that the heart is beating effectively
How do you check to see if the heart is beating effectively?
- feeling pulse
- checking CRT
- blood pressure monitor
What is the normal systolic blood pressure for a dog and cat?
110 - 160 mmHg
What is the normal diastolic blood pressure for a dog and cat?
60 - 100 mmHg
What does normal blood pressure indicate?
adequate blood circulation
What is hypotension?
low blood pressure
What can cause hypotension during anesthesia?
- anesthesia being too deep
- blood loss
When can hypotension be serious?
if a patient is in shock or dehydrated
What is hypertension?
high blood pressure
Is hypertension a problem in veterinary anesthesia?
Where can we palpate for a pulse during anesthesia?
What is "pulse deficit"?
- there is not a pulse with every heartbeat
- this is abnormal
What is a normal CRT?
under 2 seconds
When does the CRT become prolonged?
when BP drops below 70 - 80 mmHg
Does urine decrease or increase when the BP drops?
Describe how to monitor BP.
- put cuff around limb
- inflate until pressuure cuts off arterial flow
- pressure is then decreased until blood flows again
How do you detect blood reflow?
- stethoscope (done with humans)
- doppler device
What is an oscillometer?
detects vibration of blood reflow
What is a doppler device?
detects ultrasound echo of blood reflow
What 2 ways do we detect blood pressure?
How do we do direct venous BP monitoring?
- find central venous pressure
- place catheter through jugular to heart (tip at right atrium)
- not usually done in veterinary medicine
How is the rate of CRT done?
rate of return of color to mucous membrane after gentle finger pressure
What is a normal CRT?
under 2 seconds
What causes a prolonged CRT?
- anesthesia too deep
What are the different locations to check the CRT?
- gums, tongue
- prepuce, vulva
What do the different colors mean...
pale or white
blue or purple
- pink: normal for dogs
- pale pink: normal for cats
- pale or white: anemia, blood loss
- blue or purple: cyanosis - lack of O2
- yellow: icterus, jaundice - liver or hemolysis problem
- red: local inflammation or septicemia
- black: pigment - not a problem, but interferes
How much blood can a dog or cat lose?
15% of total blood volume (about 13 ml/kg)
How can you estimate blood loss during surgery?
3x3 sponge holds about 6 - 15 ml of blood
What is the normal respiratory rate for a dog?
10 - 30 bpm
What is the normal respiratory rate for a cat?
25 - 40 bpm
What is the respiratory rate during anesthesia?
8 - 20 bpm
What is tachypnea?
What is a normal respiratory pattern?
- 1:2 ratio inspiration:expiration
- inhale 1 1/2 seconds
- exhale 3 seconds
What is tidal volume?
volume of air taken in per breath
What happens to tidal volume during anesthesia?
Why does the tidal volume decrease during anesthesia?
due to decreased ability of muscles of respiration to contract
What is hypoventilation?
- decreased rate and depth of respiration
- patient retains CO2
- becomes acidotic
- common under anesthesia
What is hyperventilation?
- increased rate and depth of respiration
- patient blows off CO2
- becomes alkalotic
What are the causes of hyperventilation and tachypnea (anesthesia)?
- metabolic acidosis
- retained CO2 - bad CO2 absorber on machine
- underlying respiratory disorder
- response to pain - surgical stimulus
- recovery from anesthesia
What is panting?
rapid rate, shallow depth of respiration
What is the purpose of panting?
- temperature control
- CO2 levels stay normal
What kind of drug can cause panting?
What is atelectasis?
- partially collapsed alveoli
- not breathing deeply will cause alveoli to collapse and stick together
What causes atelectasis?
hypoventilation under anesthesia
What does "bagging" the patient mean?
pressure on reservoir bag to fully inflate lungs
Whats another name for "bag the patient"?
What is dyspnea?
What is dyspnea due to?
- airway obstruction
- mechanical (example...blocked tube)
Describe "rocking boat" respiration.
When does "rocking boat" respiration occur?
occurs under very deep anesthesia
How does "rocking boat" repiration happen?
incoordination of respiratory muscles
What is apneustic pattern breathing?
inspiration followed by prolonged pause before expiration
When does apneustic pattern respiration normally occur?
cats under ketamine
What are some normal respiratory sounds?
gentle blowing sounds
What are some abnormal respiratory sounds?
What is PaO2?
- arterial O2 pressur or concentration
- is the patient getting enough oxygen?
What is PaCO2?
- arterial CO2 pressureor concentration
- is the patient blowing off enough CO2?
How does PaCO2 occur?
- CO2 buildup occurs under anesthesia due to hypoventilation
- causes respiratory acidosis
What is a pulse oximeter?
measures % hemoglobin saturation with O2
What is the normal pulse oximeter?
What is the normal temperature for dogs and cats?
100.5 - 102.5
When should the temperature be checked during anesthesia?
every 30 minutes
What is the most common place to take an animals temperature?
What are some other locations to take a temperature?
What are the causes of hyperthermia?
- surgical prep - shaving, scrubbing, alcohol
- unable to shiver - little muscle activity
- lower metabolic rate - less heat generation
- surgery - body opened
- certain drugs - vasodilation, heat loss
- stainless steel table - cold
- position - spread out - most heat lost through head and feet
What causes a prolonged recovery?
slower metabolism - slower enzymatic breakdown of anesthetic drugs in the body
What causes excessive shivering?
- during and after recovery (reflex response to hypothermia)
- increases O2 demand
- patient may get hypoxia
What are ways to prevent hypothermia
- heating pad
- towels and blankets
- warm IV fluids
- hot water bottles
Is hyperthermia common in anesthesia?
What is the treatment for hyperthermia?
cold compresses, cold bath, alcohol rub, ice packs
What are reflexes?
involuntary response to a stimulus - from spinal cord
Why are reflexes important in anesthesia?
help to indicate depth of anesthesia
What are palpebral reflexes?
How do you test an animals palpebral reflexes?
lightly tap animal's lateral or medial canthus
Why is the swallowing reflex important during anesthesia?
when this reflex returns during recovery, we can remove the trach tube
How do you test an animals pedal reflex?
pinch toe and animal flexes leg
What animal do we use the ear flick reflex for?
How do we test a cats ear flick reflex?
stroke the hair inside the ear and the ear twitches
How do we test an animals corneal reflex?
put a drop of water in eye and the animal will blink and pull eyes back
When does an animal lose it's corneal reflex?
stage lll, plane 4
What is the laryngeal reflex?
How do we test for the laryngeal reflex?
- touch vocal cords
- cords close
Why is the laryngeal reflex important?
must abolish before intubation