Lecture 14: Inhalant Anesthesia Flashcards
What is MAC value
Minimum alveolar concentration of an inhaled anesthetic in the alveoli that will produce immobility in 50% of tested population during a surgical incision
MAC is a measure of ___ and is used for comparing anesthetics
Potency
What are the percentages of anesthesia machine gases: iso, O2, and CO2
Iso: 2%
O2: 94%
CO2: 5%
95% of patients should hold still at MAC of ___
1.2%
100% of patients should hold still at MAC of __
1.5%
What are some factors that decrease MAC
Pregnancy, hypercapnia (PaCO2 >95), hypoxemia (PaO2 <40), hypotension (MAP <50), hyponatremia, systemic disease, hypothermia, increasing age, drugs that suppress CNS
What are some factors that increase MAC
Hyperthermia, hypernatremia, CNS stimulants, hyperthyroidism
What are some factors that increase alveolar concentration
Higher inspired concentration, greater ventilation rate, poor solubility in blood and peripheral tissues
What factors lower alveolar concentration
High CO and high solubility
How can we asses CNS
Palpebral reflex, jaw tone, eye position
What is ideal eye position, palpebral reflex, and muscle tone for surgery
Eyes: Ventral
Absent palpebral
Muscle tone- relaxed
What is the depth of anesthesia if eyes are central, medial canthus palpebral present and relaxed to strong muscle tone
Too light
What is depth of anesthesia if eye positions are central, palpebral is absent and muscle tone is relaxed
Too deep
Isoflurane can cause ___in swine
Malignant hyperthermia
Which is more potent iso or sevo
Isoflurane
Raising the ___partial pressure of an inhalant is key to get the patient anesthetized
Alveolar
How does elimination of anesthetic occur
Pulmonary exchange
What are the cardiovascular effects of sevoflurane, Isoflurane, desflurane
Reduce systemic vascular resistance and maintain CO
Isoflurane and desflurane increase SNS, increase HR and CO2
Which inhalant has the least effects on HR
Sevoflurane
BP= ___x___
CO X SVR
Inhalants cause a dose dependent ___in BP
Decrease
Which inhalants are most likely to cause decrease BP
Isoflurane and sevoflurane»_space;>desflurane
What is the treatment for hypotension caused by inhalants
- Decrease inhalant concentration
- Add drugs that don’t depress CVS: fentanyl, lidocaine, ketamine, local anesthesia
- IV fluids
What are the respiratory side effects of inhalants
Decrease ventilators response to CO2 and hypoxemia
Decrease TV
Respiratory rates increase
