Flashcards in Pharm Quiz #7 Deck (59):
What is defined as stage 1 of anesthesia?
It is the analgesia stage. It is from the beginning of induction to loss of consciousness.
What is defined as stage 2 of anesthesia?
It is the excitement or delirium stage. It is from the loss of consciousness to onset of automatic breathing. Eyelash reflex disappears. Coughing, vomiting & struggling may occur; respiration irregular with breathing-holding.
What is defined as stage 3 of anesthesia?
This is the stage of surgical anesthesia. It is from onset of automatic respiration to respiratory paralysis, divided into four planes.
What is defined as Plane 1 of stage 3 of anesthesia?
It is the onset of automatic respiration to cessation of eyeball movements. Eyelid reflex lost, swallowing reflex disappears, marked eyeball movement may occur, conjunctival reflex is lost a the bottom of the plane.
What is defined as Plane 2 of stage 3 of anesthesia?
It is the cessation of eyeball movements to beginning paralysis of intercostal muscles. Laryngeal reflex lost, corneal reflex disappears, secretion of tears increases(a useful sign of light anesthesia), respiration automatic & regular, movement & deep breathing as response to skin stimulation disappears.
What is defined as Plane 3 of stage 3 of anesthesia?
THIS IS THE DESIRED PLANE FOR SURGERY, ESPECIALLY WHEN MUSCLE RELAXANTS WERE NOT USED.
It is from the beginning to the completion of intercostal muscle paralysis. Diaphragmatic respiration persists, progressive intercostal paralysis, pupils dilated & light reflex is abolished.
What is defined as Plane 4 of stage 3 of anesthesia?
From complete intercostal paralysis to diaphragmatic paralysis.
What is defined as stage 4 of anesthesia?
From stoppage of respiration to death.
-medullary paralysis with respiratory arrest and vasomotor collapse
-pupils widely dilated and profound muscle relaxation.
How are lipid solubility, OGPC and potency related?
Poor lipid solubility = lower OGPC = Less Potency
What are the hallmark characteristics of the insolubility of desflurane?
-precise control of anesthetic concentrations
-prompt recovery independent of length of anesthesia(the longer the case the more valuable desflurane is)
What are the pharmacoeconomics of desflurane?
Desflurane is more expensive/bottle but there is a cost savings of rapid induction and early wake-up. With longer to sleep\wake-up times and flows required for closed circuit technique will actually spend more money using sevoflurane.
What are the physical properties of desflurane?(vapor pressure, odor, BGP, MAC and chemical significant in relation to isoflurane?
vapor pressure = 669
odor = ethereal or monkey perfume
BGP = 0.42
MAC = 6.6%
Desflurane is isoflurane with the chloride atom replaced with a fluorine.(3X greater vp than iso/5X less potent than iso)
*desflurane will never be cheaper than isoflurane because it is made from isoflurane*
What is the only measurable metabolite found in desflurane?
What are the airway characteristics of the use of desflurane?
At what concentration are the airway irritant properties usually seen in desflurane?
Occurs mainly @ concentrations greater than 6%. Airway irritant if inspired concentrations are increased rapidly.
What is a method used to avoid the airway irritant properties that characterize desflurane?
Avoided by incremental increases of inspired concentrations 2% every 2-3 breaths
What are the characteristics of the insolubility of desflurane?
-rapid achievement of alveolar(alveolar=brain) partial pressures necessary for anesthesia
-Fi quickly approximates Fa
-lower blood gas solubility
-more rapid recovery
Desflurane has the lowest tissue solubility(T/F)?
Does desflurane provide retrograde amnesia?
How does desflurane affect cerebral blood flow?
decreases cerebral metabolic rate of O2 consumption
decreases cerebral activity
increases cerebral blood flow(increases ICP)
What effect does desflurane have on an EEG at < 0.4 MAC?
increased frequency and voltage
What effect does desflurane have on an EEG at 0.4 MAC?
begins to reduce CMRO2
What effect does desflurane have on an EEG at 1 MAC?
decrease in EEG frequency, maximal voltage occurs
What effect does desflurane have on an EEG at 1.5 MAC?
suppression of burst activity
What effect does desflurane have on an EEG at 1.5 - 2 MAC?
electrical silence-no s/s of seizure activity
At what MAC does desflurane increasingly depress evoked potentials?
0.5 MAC; the use of nitrous with desflurane does not abolish this characteristic
At what MAC does desflurane produce increased cerebral blood flow?
> 0.6 MAC with normocapnia desflurane produces:
-reduced cerebral vascular resistance
these changes occur in minutes
How long does CBF last with desflurane?
up to 4 hours, you only need to hyperventilate for 4 hours if patient has a space occupying lesion
How does the CMRO2 reduction of desflurane compare to isoflurane and sevoflurane?
less than isoflurane
comparable to sevoflurane
How does desflurane affect ICP?
desflurane will raise ICP. Patients with space occupying intracranial lesions are at increased risk.
What is the MAC in which desflurane increases ICP?
0.8 - 1.1 MAC
What is the treatment to offset the increased ICP properties of desflurane?
What are the circulatory characteristics of desflurane?
-lower system BP
-increased HR(compensatory affect secondary to reduced SVR)
-alterations in CO, SV, RAP
-reduction of SVR
-alterations in heart rhythm
-alterations in coronary blood flow
What is the cause of a decrease in MAP that is caused by desflurane and what can be done to offset this affect?
SVR and it can be offset by substitution of nitrous for an equal MAC portion
What effect does desflurane have on heart rate?
Desflurane increases heart rate secondary as a compensatory mechanism of decreased SVR. This phenomenon is less in the elderly. Des does not cause dysrhythmias or Q-T interval changes. Also does not alter the carotid sinus/SA
How might desflurane's effect on heart be blunted or treated?
This effect is blunted by many drugs including: opioids an beta blockers
How does desflurane effect cardiac output?
Left ventricular stroke volume is reduced 15-30% in patients who receive desflurane, just like isoflurane and sevoflurane.
How long are the stroke volume effects of desflurane seen?
This effect dissipates within 5 hours of desflurane anesthesia.
How does desflurane effect heart pressures?
raises right atrial pressure
does not appreciably alter pulmonary vascular resistance
By what mechanism does desflurane decrease SVR?
primarily due to increased(up to 4 times) skeletal muscle perfusion.
What sites mediate the neurocirculation response to desflurane?
How is the neurocirculation effects of increased HR an BP treated?
What are 4 effects does desflurane have on the patients myocardium?
1. inhibition of CNS outflow
2. autonomic ganglionic blockade
3. decreases catecholamine release
4. decreased influx of calcium ions
*also may afford myocardial protection against prolonged ischemia & repercussion injury*
Does desflurane play any part in Coronary Steal?
Desflurane not clinically significant with Coronary Steel.
Phrase used to described the breathing pattern of patient on desflurane.
"lizard on a hot rock"
Desflurane produces increases in RR up to what mac?
At what MAC does apnea occur with desflurane?
1.5 - 2 MAC
How is the best way to control the desflurane mediated ventilatory depression/alteration?
What affect does desflurane have on the hepatic system?
Total hepatic blood flow and hepatic artery blood flow are maintained. There may be transient increases in LFTs following desflurane administration.
*****Post-op liver dysfunction may occur--->may be associated with hepatocyte hypoxemia*****
How is desflurane metabolized?
Desflurane oxidative metabolized by cytochrome P-450 to form acetylated liver protein adducts by mechanisms similar to halothane.
How does desflurane affect the Renal system?
produces dose dependent decreases in renal blood flow, GFR and urine output
By what mechanism are the affects of desflurane on the renal system?
reduced SVR and cardiac output
***should be treated with pre-op hydration***
Is there any compound A or free fluoride ion problems with desflurane administration?
How does desflurane affect the neuromuscular junctions?
provides dose dependent enhancement of NM blockers.
This effect is similar to isoflurane/sevoflurane. Desflurane will trigger MH, but is a less potent trigger than halothane.
At what MAC does desflurane produce decreases in uterine smooth muscle contractility?
modest changes @ 0.5 MAC and significant decreases in uterine smooth muscle contractility @ 1 MAC
Desflurane should be avoided in OB
Does desflurane decrease resistance to bacterial infections, alter leukocyte phagocytotic function or is it a mutagenic or carcinogenic?
Where is the site of metabolism for desflurane?
ether bond or ether-halogen bonds
greater metabolism with higher inspired concentrations
What percent metabolism is desflurane?
0.02%(know the metabolism % of all 4 VA for final exam)
metabolic pathways parallels that of isoflurane, results in inorganic fluorides, trifluoroacetic acid, CO2 and water