Chapter 21 Anesthesia Principles and Monitoring Flashcards
Oxygen: Cylinder type, color, pressure and volume
Oxygen: green
E - 1900 PSI and 660 L
H - 2200 PSI and 6900 L
Medical Air: Cylinder type, color, pressure and volume
Medical air : Yellow
E - 2200 PSI and 6550 L
Nitrous oxide: Cylinder type, color, pressure and volume
Nitrous Oxide: Blue
E - 745 PSI and 1590 L
Carbon Dioxide: Cylinder type, color, pressure and volume
Carbon dioxide: grey
E - 838 PSI and 1590 L
Nitrogen: Cylinder type, color, pressure and volume
Nitrogen: Black
H - 2200 PSI and 6400L
What are three indications for IPPV
- Hypoventilation
- Manipulate alveolar ventilation in hypoxemic patients
- Limit atelectasis
When is positive pressure maintained during IPPV
Positive pressure is maintained only during inspiration
Tidal volume in dogs
Tobias: 15ml/kg
Lumb and Jones: 10 - 20ml/kg
Label the inspiratory, expiratory, and APL valves
Why should a patient ≥ 5kg use a rebreathing system
Dead space exits the rebreathing system where the inspiratory and expiratory breathing tubes meet at the patient (the Y piece). This is enough to cause rebreathing of CO2 in small patients
How much is the fresh gas flow rate in a non-rebreathing system in relation to the patients respiratory minute volume
At least 3x the patients respiratory minute volume
Non-rebreathing requires a high flow rate to prevent rebreathing. What is the recommended flow rate
200-500 ml/kg to prevent rebreathing
What is the flow rate of the oxygen flush valve
30-50L/min which can cause significant barotrauma and should not be used in non-rebreathers
What does the one-way valve system on the rebreathing circuit do
The circle (aka rebreathing) system incorporates one-way valves to prevent immediate rebreathing of exhaled gas
Pressure regulator function
An internal pressure regulator reduces the carrier gas pressure from that in the tank or wall outlet to 50 PSI
What are the ingredients in soda lime
Sodium hydroxide, potassium hydroxide, water, and calcium hydroxide
Soda lime MOA
CO2 reacts with water to form carbonic acid which then dissociates to free protons and carbonate
How could a dual flow meter aid in preventing alveolar collapse
Dual flow meter is used to mix two gases. To prevent alveolar collapse mix 100% oxygen with medical air or nitrogen. Nitrogen will provide a scaffold for alveoli once all O2 is removed by pulmonary blood flow
How does a higher fresh gas flow affect soda lime
The absorbent may lose water to evaporation and become less effective
What is PEEP and IPPV effect on cardiac output
PEEP benefits oxygenation without negatively impacting cardiac output and prevents alveolar collapse
IPPV depresses CO
What causes a progressive increase in ETCO2 plateau
Hypoventilation
What causes a progressive decrease in ETCO2 plateau
Hyperventilation
Causes of hypoventilation
Neuromuscular disorders
Diaphragmatic hernia
Pleural space disease
Flail chest
Airway obstruction
CNS disorders
CO2 in tissues is increased and the lungs are incapable of expelling the excess - Malignant hyperthermia and heatstroke
Purpose of adding helium to oxygen
Helium may be combined with oxygen in a 70:30 ratio to protect against fires caused by laser ignition of anesthetic carrier gas.
Cause of absorption atelectasis
Oxygen is rapidly absorbed from the alveoli. An alveolus filled with 100% oxygen will gradually collapse as that oxygen is removed by the pulmonary blood flow.
How to prevent absorption atelectasis
Mix with other gas such as nitrogen which provides structural support to the alveolus or PEEP at 5cm H2O.
Is the inhalant vaporizer knob indicative of the concentration of inhalant in the rebreathing circuit? Explain
No, the circuit concentration of the inhalant to start is 0%. Incoming inhalant increases the concentration but there’s some already in the circuit so it’s diluted and doesn’t match what’s set on the vaporizer.
Is the inhalant vaporizer knob indicative of the concentration of inhalant in the non-rebreathing circuit? Explain
Yes - common gas outlet enters near the patient, the gas from the common gas outlet is delivered directly to the patient. - no dilution occurs as does with rebreathing system
If rebreathing of CO2 is seen on capnograph but absorbent is not discolored, does the absorbent need to be changed
Yes
T/F: If flow rate is high then the condensation results in an increased weight of CO2 obsorbent
False, At higher fresh gas flows, the absorbent may lose water to evaporation and become less effective
Label each
A. Normal
B. Hypoventilation
C. Rebreathing CO2
D. Leak
E. Hyperventilation
F. Cardiac arrest
How do one way valves affect gas flow
During inspiration, the inspiratory one way valve opens, allowing gas to move from the fresh gas inlet and reservoir bag to the valve into the inspiratory limb of the breathing circuit
During expiration, the inspiratory valve is closed , preventing exhaled gas from entering the inspiratory limb of the breathing circuit, forcing it into the expiratory limb of the breathing circuit
The inspiratory valve helps direct gas into the expiratory limb of the breathing system
How to calculate reservoir bag
[BWkg x TV (10-20 ml/kg)] x 5-10
5-10 x the patients normal tidal volume
How are vaporizers classified (5 classes)
Regulation of vapor output
Method of vaporization
Vaporizer location in the anesthetic circuit
Temperature compensation
Agent specificity
MOA of beta-blockers when given under anesthesia to decrease blood pressure
Control blood pressure through reduction in HR and CO
Also inhibit RAS due to blockade of B1-adrenergic receptors at the juxtaglomerular apparatus
What is the order of MAC in dogs and cats for isoflurane, sevoflurane, and desflurane
Dogs have a lower MAC
Isoflurane 1.3%
Sevoflurane 2.1%
Desflurane 7.2%
Cats have a higher MAC
Isoflurane 1.7%
Sevoflurane 3.1%
Desflurane 10.3%
What are the cardiovascular effects of IPPV
Alters CV function by changing the intrathoracic pressure and lung volume. This effects CV directly by altering preload, after load, and/or HR.
Intrapleural pressure increases during inspiration, leading to a decrease in venous return and right ventricular output
IPPV increases vagal tone and reduces sympathetic input therefore decreasing heart rate - which decreases cardiac output.
What are the physicals signs of anesthetic depth within stage III
Plane 1 - light - central eyeball position, positive palpebral, medium to large pupil size, positive PLR, Moist cornea, lots of eyelid muscle tone, lots of mandibular muscle tone, reflex movement to nociception - maybe, physiologic response to nociception present
Plane 2 - Light-medium - rotated or med/vent eye ball, absent palpebral, small to medium pupil size, positive PLR, moist cornea, some eyelid muscle tone, some mandibular muscle tone, no reflex movement to nociception, maybe physiologic response to nociception
Plane 3 - Deep-medium - rotated or med/vent eyeball, medium to large pupil size, absent PLR, intermediate corneal moistness, little eyelid and mandibular muscle tone, absent physiologic response to nociception.
Plane 4 - Deep - Central eyeball, large pupil size, dry cornea, absent eyelid and mandibular muscle tone
Define hyperalgesia
An exaggerated and prolonged response to a noxious stimulus
