L&J Chp 27 Phys, Pathophys, Ax Management of Patients with Respiratory Dz Flashcards
Normal changes in resp fxn seen in anesthetized animal compared to conscious, awake, spont breathing animal
- PaO2 often lower than observed with same species for same FiO2
- PaCO2 usually above conscious resting values if anesthetized patient spontaneously breathing
- Increased airway resistance unless intubated
What are some other things that affect resp function in our anesthetized patients?
- Positioning
- Concurrent drug use
- Magnitude of preax cardiorespiratory dysfunction
What are three important considerations of respiratory function as it pertains to GA?
- Neural control of resp, its effect on alveolar ventilation (VA)
- Influence of GA on airway, lung volumes, chest wall
- Alterations in vent-perfusion relationships during GA
What are the two respiratory function parameters that can be measured in conscious animals?
- TV
- FRC
(others require patient cooperation, GA)
Respiration
Total process whereby oxygen is supplied to, used by body cells; CO2 eliminated by means of gradients
Ventilation
Movement of gas into, out of alveoli
-Ventilation requirement for homeostasis varies with body size, level of activity, body temp, ax depth
Pulmonary Ventilation
Accomplished by expansion, ctx of the lungs
Eupnea
Quiet, ordinary breathing
Dyspnea
Labored breathing
Tachypnea
Increased RR
Hyperpnea
Fast +/- deep respiration, indicating “over respiration”
Polypnea
Rapid, shallow, panting type of respiration
Bradypnea
Slow, regular respiration
Hypopnea
Slow +/- shallow breathing –> under respiration
Apnea
Transient (or longer) cessation of breathing
Cheyne-Stokes respirations
Increase rate, depth then become slower followed by brief periods of apnea
Biot’s respirations
Sequences of gasps, apnea and several deep gasps
Kussmaul’s respirations
Regular, deep respirations without pause
Apneustic Respirations
Animal holds an inspired breath at the end of inhalation for short period of time before exhaling
Tidal volume (VT or TV)
Volume of air inspired or expired in one breath
Inspiratory reserve volume (IRV)
Volume of air that can be inspired over, above normal tidal volume
Expiratory Reserve volume (ERV)
amount of air that can be expired by forceful expiration after N expiration
Residual volume (RV)
Air remaining in the lungs after most forceful expiration
Minute ventilation (VEmin) or minute respiratory volume
VT x RR
Inspiratory capacity (IC)
TV + IRV
Amount of air that can be inhaled starting after a normal expiration and distending the lungs to maximum amount
Functional residual capacity (FRC)
ERV + RV
Amount of air remaining in the lungs after normal expiration
-At FRC, inward ‘pull’ of lungs due to their elasticity equals outward ‘pull’ of chest wall
Vital Capacity (VC)
IRV + TV + ERV
Maximum amount of air that can be expelled from the lungs after first filling them to maximum capacity
Total lung capacity (TLC)
IRV + TV + ERV + RV
maximum volume to which the lungs can be expanded with the greatest possible inspiratory effort (or by full inflation to 30cm H20 airway pressure when patient anesthetized)
Main differences btw managing resp in human med vs vet med
- IV anesthetics used without supplemental O2
- Less use of peripheral muscle relaxants
- IPPV sometimes, not always
- Carrier gas = 100% O2 whereas in ppl, 2:1 mixture of air, N2, N2O, O2
4 major components of the resp system
- Neural control
- Bellows mechanism (chest wall, diaphragm)
- Upper and lower airway
- Parenchyma
Control of respiration
- Central respiratory center
- Central peripheral chemoreceptors
- Pulmonary reflexes
- Non-resp neural input
