Exam 1 Flashcards
What are the five components of general anesthesia
- Unconsciousness
- Muscle Relaxation and immobility
- Amnesia- can’t remember anything
- Attenuation of autonomic reflexes- keeps sympathetic NS from being activated
- Analgesia- relieving pain before it even happens
What are the risk factors for general anesthesia
old age, high ASA status, urgent/emergent procedure, procedure preformed at night, very small size, endotracheal intubation in cats (don’t over inflate cuff), pulse ox not used
What are the risk factors and risk of general anesthesia
Anesthetic drugs have the smallest therapeutic index of any drugs we use, dogs have a 0.17% chance of dying under anesthesia, cats have 0.24%, horses if healthy have a 1% if unhealthy have a 2% chance, and rabbits have a 0.73% chance of death if healthy and if sick a 7.37% chance of death
Patients can die from overdoses, cardiovascular or respiratory complications, or other reasons like anaphylaxis or aspiration
Describe the American Association of Anesthesiologist (ASA) classification
ASA 1- normal healthy patient, elective procedure
ASA 2- patient with mild systemic disease (like dental disease)
ASA 3- Patient with severe systemic disease (diabetes or cushings)
ASA 4- Patients with severe systemic disease that is a constant threat to life (ex. HCM or pneumothorax)
ASA 5- moribund patients not expected to survive one day with or without operation
What are the components of a patient pre-anesthetic assessment
Identification of the animal
Signalment- age, breed, species, sex
Body weight in kilograms
History
physical exam
What are the minimum components of pre-anesthetic testing
Everyone should get a PCV/TS
If indicated minimum database (CBC, Chem, UA)- geriatric (achieved >70% of life expectancy) are always indicated
When should you do further diagnostics prior to anesthesia
If geriatric (minimum database) or if something found on physical (abnormal auscultation on respiratory or cardio, if needs parasite testing, if anything is concerning in history, etc.)
What are the appropriate fasting times for patients undergoing anesthesia
Healthy dogs and cats- 6 hours
Ruminants- 24 hours
Pigs- 12 hours
Horses- maybe 12 hours
Neonates and tiny creatures (<2kg)- 1-2 hours (hypoglycemia concern)
How do you prep a patient for anesthesia
Fast for appropriate about of time
Resolve and deficits or abnormalities- dehydration, electrolyte abnormalities, heart failure, anemia, respiratory distress
Supportive care- temp support, pre-oxygenate, place monitors to get first readings
Informed consent from owner
What does the circulation of blood depend on
A functional heart (pump)
Normal vasculature (pipe)
Adequate blood volume (fluid)
What is the function of the cardiopulmonary system
to maintain a constant internal environment for all cells
How do anesthetics usually impact the mechanical activity of the heart
by altering the electrical potential across membranes (affect Na, K, Ca, and Cl)
What is meant by excitability of cardiac cells
the intrinsic property they have to generate an action potential
What are the steps of an action potential for non-pacemaker cell
Phase 0- Rapid inward Na flux- depolarization
Phase 1- Transient outward K flux- initial repolarization
Phase 2- Large, slow inward Ca flux trigger Ca release and cell contraciton
Phase 3- Outward K flux- repolarization
Phase 4- resting
What are the steps of an action potential for a pacemaker cell
Phase 0- slow inward Na and Ca flux- slow depolarization
Phase 1- none
Phase 2- Large, slow inward Ca flux trigger Ca release and cell contraciton
Phase 3- Outward K flux- repolarization
Phase 4- slow inward Na flux- slow depolarization
What are all the pacemaker cells and which one usually sets the heart rate
SA and AV nodes, bundle of His, R and L branches, and Purkinje fibers
SA node usually sets heart rate because it has the most rapid rate of phase 4 (usually)
How does calcium cause a muscle contraction
it binds to troponin C which enables the actin to interact with the myosin and cause a muscle contraction
What makes up the distribution of total blood flow
Vessel rich group (brain, kidneys, heart, etc)- 75% of blood distribution
Muscle group
Fat group
vessel poor group
How do anesthetics interact with cardiovascular function and how can you minimize the effect
most of them depress CV function by causing hypotension, bradycardia, and decreased contractility
minimize by careful dosing and balanced anesthesia and ensuring adequate delivery of oxygen
What makes up your inspiratory capacity? How about the functional reserve capacity of your lungs
Inspiratory is your inspiratory reserve volume and your tidal volume
Functional reserve capacity is the expiratory reserve volume and residual volume
What makes up your vital capacity
The inspiratory and expiratory reverse volumes and tidal volume (excludes residual volume)
What makes up your upper airway and what is this considered
nasal passages, larynx, trachea, bronchi, bronchiole- it is the anatomic dead space
Inspiration has what kind of pressure and expiration has what
inspiration has slight negative intrathoracic pressure and expiration has slight positive pressure
Explain the two ends of the range of V/Q matching
V/Q= infinity means there is great ventilation but no perfusion
V/Q= 0 means there is no ventilation but good perfusion
What determines oxygens delivery to tissues
cardiac output and blood oxygen content (CaCO2) aka affinity of Hb for O2
What components make up CaO2 (blood oxygen content)
the oxygen bound to hemoglobin and the oxygen dissolved in plasma
Explain the benefits of hand monitoring and machine monitoring
Hand monitoring can be more subjective whereas something like a machine can give you exact numbers or show you exact problems (like an arrhythmia on an ECG)
Hand measuring with a doppler is actually more accurate than oscillometric
What is used to assess anesthetic depth
jaw tone (loose), eye position (central if light or deep, ventromedial if adequate), palpebral/corneal reflexes (absent if deep), rectal tone (absent if deep)
What are examples of subjective cardiovascular monitoring
Mucous membranes, capillary refill time, cardiac auscultation, pulse palpation
Describe the parts of the ECG
P wave- atrial depolarization
QRS- ventricular depolarization and contraction
T- repolarization of ventricle
Where do the ECG leads usually go on small animals
White- right forelimb
Black- left forelimb
Red- left hindlimb
Explain a sinus arrhythmia
The heart rate increases in inspiration and decreases in expiration- normal in dogs and horses
What is a 1st, 2nd, and 3rd degree AV block
1st- there is a prolonged P-R interval
2nd- occasional dropped QRS
3rd- no relationship between P and QRS- sinus node and ventricle not speaking, ventricle beats without a p wave
What does atrial fibrillation look like
F waves, high ventricular rate, irregular rhythm, no set p waves and random QRS
What does a ventricular premature complex (VPC) look like
wide and bizarre QRS with no p wave
What is systolic blood pressure
the peak pressure reached by arterial pulses
What does Pulse Ox measure
The percent of hemoglobin saturated with oxygen
What is the driving force for loading oxygen onto hemoglobin
The partial pressure of oxygen (PaO2)
What is hypoxemia in terms of PaO2
When PaO2 is less than 60mmHg, after this saturation rapidly falls
How does pulse oximetry work
it uses alternating red and infrared light to analyze pulsatile fluid (aka the blood in the arteries) to see how much the hemoglobin is saturated with oxygen
What are examples of subjective and objective monitoring for ventilation
Subjective- respiratory rate and depth
Objective- Capnography and blood gas analysis
Capnography is an indirect measurement of what
the patients cardiac output and metabolic rate
a decrease in CO2 means there is a decrease in cardiac output
Inadequate ventilation is represented as what on capnography
A high ETCO2 (hypercapnia), represents hypoventilation
Excessive ventilation is represented as what on capnography
A low ETCO2 (hypocapnia), represents hyperventilation
What is normal ETCO2 ventilation range
35-45mmHg
What corresponds to the end expiration on a capnogram
the beta angle