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53 Cards in this Set

  • Front
  • Back
Static Lung Volumes
Static Lung Volumes
-A: Inspiratory reserve volume
-B: Tidal volume
-C: Functional residual capacity
-D: Vital capacity
-E: Total lung capacity
-F: Expiratory reserve volume
-G: Residual volume
Residual lung volume
-define
-volume remaining when as much air as possible is removed from the lungs
Expiratory reserve volume
-purpose
-needed for exercise to oxygenate blood effectively
Minute ventilation
-equation
V(E) = V(T) x f
Minute ventilation = Tidal volume x frequency
Minute ventilation
-effect of increase
-effect of decrease
-inc. = hyperventilation
-dec. = hypoventilation
Why is hypoventilation difficult when the patient is awake?
-CO2 is a potent respiratory stimulant
Tidal volume
-equation
V(T) = V(A) + V(D)

Tidal volume = Alveolar volume + Dead space volume
Normal ratio of alveolar volume to dead space volume
-2/3 alveolar volume
-1/3 dead space volume
When can dead space volume increase?
-when breaths are smaller
Anesthetic effects on ventilation
-many sedatives, tranquilizers, induction agents, and modern inhalation anesthetics reduce ventilation
-hypoventilation
Potent ventilation depressant drugs
-opioids

-all inhaled agents depress ventilation
Pulmonary changes in anesthetized patients
-dec. lung volume
-inc. intrapulmonary shunt
-inc. PaCO2
-dec. PaO2
-dec. tidal volume
Pulmonary changes are affected greatly by anesthesia in what sp?
-horse
Definitive measure of pulmonary ventilation
-PaCO2
PaO2 levels
-useful for
-determining oxygenation issues
Values that are not good indicators of ventilator adequacy
-tidal volume
-minute ventilation
-frequency
-flow

***PaCO2 defines ventilation
Ventilation values that can help to monitor anesthetic depth
-frequency
-flow
Horse v. Dog
-effects of inhaled induction agents
-more profound hypoventilation in the horse
-decreased PaO2 in larger animals (horse) due to pulmonary dysfunction
MAC of inhaled anesthetics for surgical procedures
about 1.5x MAC
Spontaneous ventilation
-define
-patient determines rate, rhythm, and volume of breathing
Controlled ventilation
-define
-the anesthetist controls rate, rhythm, volume, and flow of each breath
Mechanical Ventilatory Support
-indications for use
-depression of respiratory centers by anesthetics
-limitation to thoracic movement
-diaphragmatic hernia
-ineffective respiratory exchange
-thoracic surgery
-anesthetic management
Limitation to thoracic movement
-examples
-bulldog w/ smaller thorax
-tight bandaging
Reason thoracic surgery is an indication for mechanical ventilator support
-when the thorax is opened, the lungs collapse from the ribs being unable to be held open
Mechanical ventilator support
-goals
-reduce PaCO2
-reduce work of breathing
-increase PaO2
Intermittent Positive Pressure Ventilation (IPPV)
-cardiovascular effects
-Inc. intrathoracic pressure
-Dec. venous return
-Dec. cardiac output
-Dec. blood pressure
-Dec. pulmonary blood flow

*All changes proportional to the mean pressure in the thorax
Manual IPPV for anesthetized patients
-procedure
-close pop-off valve
-squeeze rebreathing bag
-stop squeezing to allow rebreathing bag to fill with expired gas
-periodically open pop-off valve to relieve excess gas
What should the gas pressure in the circuit not get above for manual IPPV of an anesthetized patient?
-30 mL/kg/min
Mechanical ventilator
-why put the bag in a container with a hole
-bag movement depends on air flow in/out of the container

-squirt air in = give breath
-let air out = expiration
Reason to replace rebreathing bag with a bellows for mechanical ventilation
-easier to quantitate volume
Mechanical ventilator
-facts
-ventilator always connected to where the rebreathing bag was located
-ventilator bellows replace rebreathing bag
-ventilator squeezes bellows to deliver breath to the patient
Switching from a spontaneous breath to the ventilator
-procedure
-empty rebreathing bag
-close pop-off valve
-remove rebreathing bag and attach the ventilator corrugated hose
-turn pre-set ventilator on
-attach waste gas tubing from waste gas interface to ventilator waste gas outlet
-fine tune ventilator adjustments while observing patient
Switching from the ventilator to spontaneous ventilation
-procedure
-reduce minute ventilation to allow PzCO2 to rise and stimulate patient to breath (gradually reduce rate, volume, or both)
-when breathing efforts return, switch the ventilator to off
-disconnect corrugated hose and replace the rebreathing bag on breathing circuit
-open the pop-off valve
-remove waste gas from ventilator and attach to pop-off valve
-manually assist ventilation if necessary
Ventilator arrangement
-types
-single circuit
-double circuit
Single circuit ventilator
-define
-all or part of the same gas supplied to the ventilator goes to the patient
Double circuit ventilator
-gas from the ventilator compresses another device (bag/bellows) that in turn forces gas into the lungs
Single circuit ventilator
-used primarily for
-ICU
Double circuit ventilator
-used primarily for
anesthesia
Suggested ventilator settings for dogs
-frequency
-tidal volume (mL/kg)
-inspiratory time
-peak airway pressure (cmH2O)
-frequency = 8-15

-tidal volume (mL/kg) = 10-15

-inspiratory time = <1 sec

-peak airway pressure (cm H2O) = 10-15
Suggested ventilator settings for horses
-frequency
-tidal volume (mL/kg)
-inspiratory time
-peak airway pressure (cmH2O)
-frequency = 6-10

-tidal volume (mL/kg) = 10-15

-inspiratory time = 1-2sec

-peak airway pressure (cm H2O) = 20-30
Reasons patient is not accepting mechanical ventilation
-anesthetic plane is too light (inc. anesthetic delivery)
-PaCO2 is too high (inc. minute ventilation)
-PaO2 is too low (determine reasons for hypoxemia
Returning to spontaneous ventilation
-how to
Allow PaCO2 to rise
-dec. frequency
-dec. tidal volume
-both

Dec. anesthetic depth
-ocean bellows ventilator
Ocean bellows ventilator
-power source
-pneumatic
Oceanic bellows ventilator
-bellows type
-ascending bellows
Oceanic bellows ventilator
-controls
-inspiratory volume
-ventilator rate
-flow
Oceanic bellows ventilator
-how to control tidal volume
-flow
Omni-vent ventilator
-power source
-pneumatic
Omni-vent ventilator
-use
-common for non-rebreathing systems
Drager Control Ventilator
-control source
-electricity
Large animal ventilators
-types
-Surgivet DHV 1000 ventilator
-Drager Control Center
Surgivet DHV 1000 ventilator
-facts
-descending bellows
-pneumatically powered
-pneumatically controlled
-variable flow control
-infinite I:E ratios
-can deliver larger tidal volume more rapidly than drager
Drager control cent
-facts
-descending bellows
-pneumatically powered
-electronically controlled
-variable flow control
-5 I:E ratios
-breathing rates <4 breaths/min have a long inspiratory time