General Anesthesia questions Flashcards
What stage of anesthesia are patients most vulnerable in?
Stage II - because they are hyperexcitable to external stimuli and have lose both airway reflexes and autonomic stability
What is mallampati class I?
the uvula is entirely visible
What is mallampati class II?
The uvula is partially visible
What is mallampati class III?
The uvula is not visible - intubation likely to be difficult
What is ASA I?
No systemic disease. Normal Healthy
What is ASA II?
Mild systemic disease but no fxnal capacity deficits: smoking, controlled HTN
What is ASA III?
Systemic disease with fxnal capacity deficits: CAD, RAD, mild renal or hepatic impairment
What is ASA IV?
Unstable CAD, COPD, CF
What is ASA V
Imminent death - will die without intervention: ruptured aorta
What are the stages of anesthesia?
Induction, Maintenance, Emergence
What is Stage I?
Lasts from full consciousness until patient closes his eyes
Induction: analgesia, patient is awake and responsive
What is Stage II?
Last from eye closure to regaining autonomic stability
Induction: hyperexcitable, delirium, movement, autonomic instability, loss of airway protection, significant risk of complications, protective airway reflexes lost
What is Stage III?
Return of autonomic stability, preservation of vital functions. 4 planes: planes 2 and 3 are surgical anesthesia
What is Stage IV?
Maintenance: depression of vital functions, autonomic instability
What is Stage V?
Maintenance: cardiac arrest
What is emergence?
Stage III, II, I
What are the indications for tracheal intubation?
Airway access/airway protection
Need for muscle relaxation during surgery
Length of procedure greater than 2 hours
Need for mechanical ventilation
What happens to the cardiovascular system in aging?
Decreased responsiveness in beta receptors - lower HR max for compensation, arterial pressure is more labile
What happens to the pulmonary system in aging
Decreased vital capacity/pulmonary reserve, increased air trapping, increased V/Q, increased residual volume, reduced resting PaO2, decreased ventilatory response to hypoxia and decreased ability to cough and clear secretions
What classes of drugs are the elderly very sensitive to?
Sedative hypnotics
What happens to renal and hepatic function with age?
It declines leading to a reduction in drug elimination from the body
What should be assessed for in an obese patient?
Functional capacity because they could have CHF or pulmonary HTN
Social history - tobacco use! Encourage to quit smoking 6 weeks prior
What could be helpful to draw in a patient with a BMI over 50?
ABG
What are morbidly obese patients at higher risk for?
Intubation difficulty, mask ventilation difficulty, postoperative respiratory failure.
What are patients with OSA at higher risk for?
HTN, arrythmias, ACS, CHF, and sudden death due to increased baseline SNS tone.
What should be done prior to induction of an obese patient?
3-5 minutes of preoxygenation
What does preoxygenation do?
Increase PaO2
Washes out N2 thereby attenuating hypoxemia
Which inhaled anesthetics are preferred in obese patients?
Des or sevo because they have a lower tissue/blood ratio so they wear off quicker. This is important because obese patients need to be fully awake before extubation
Why should NMBs be dosed according to lean body mass?
Because obese patients have an increase in pseudocholinesterase activity
What happens to opioids in the blood when dosed based on TBW in an obese patient?
they have a higher blood level because the high amount of fat are not well perfused.
How should pain be managed in an obese patient postoperatively?
Dose according to lean body mass and deliver via PCA
What is the danger of opioid use in an obese patient?
risk of apnea/decreased respiratory drive
What other non-opioid drugs can be used for postop pain control?
NSAIDs, ketamine, dexmedetomidine (alpha agonist), local
Which drug should be dosed according to TBW in obese patients?
Succinylcholine
What is the innervation of the lower extremity?
L2 to S3
What are the risk of neuraxial anesthesia in an anticoagulated patient?
local bleeding, epidural hematoma
Where does a spinal anesthetic go?
The subarachnoid space
