Final Flashcards
Analgesia
Feel no pain
Amnesia
No memory
What comprises of balanced anesthesia?
Analgesia, amnesia, relaxation and hypnosis.
What are the desirable attributes of N2O?
Analgesic, anxiolytic, relative amnestic, rapid onset, titration, rapid cognitive recovery, minimal side effect.
Moderate Sedation
Independent airway.
Responds to physical or verbal command.
Deep Sedation
Partial loss of protective reflexes.
Inability to maintain airway.
Inability to respond to physical stimulation or verbal command.
General anesthesia
Unconciousness.
Partial or complete loss of protective reflexes.
Inability to maintain airway.
Inability to respond to physical stimulation or verbal command.
What are Guedel’s stages of Anesthesia?
Analgesia
Delirium/Excitement
Surgical anesthesia
Respiratory paralysis.
Pain
An unpleasant sensory and emotional experience arising from potential or actual tissue damage.
Provides damage protection to tissue.
Anxiety
A non-specific feeling of apprehension, worry, uneasiness, or dread the source of which may be vague or unknown.
Fear
A feeling of fright or dread related to an identifiable source recognized by the individual
Phobia
Any persistent or irrational fear of something specific such as an object, activity or situation that results in avoidance or desire to avoid the feared stimulus.
How do you assess fear and anxiety?
Physiologic indicators such as heart rate and BP. Behavioral indicators, Pt. history, anxiety questionnaires.
What controls the respiratory physiology?
Medullary center of the brainstem. Diaphragm and external intercostals assist inspiration.
Tidal volume
Volume of exhaled air after normal inspiration.
Minute Ventilation
Amount of gas brought into the lungs. In N2O sedation, concerns the amount of gas given. Tidal volume times respiratory rate.
What is the average minute ventilation?
6-7 L/min
Alveolar Ventilation
Concerns the amount of gas reaching the alveoli, and the amount capable for gas exchange. Usually about 150 mL less than the tidal volume.
What is the composition of Air?
79% Nitrogen and 21% Oxygen.
Is Nitrous Oxide dissolved in the blood?
NO! This allows for quick equilibrium in the blood and brain, and quick expulsion.
What is diffusion hypoxia?
Likely cause of post op headache, nausea, lethargy. Treated with post op 100% O2 for 3-5 min.
Nitrous oxide leaving blood causes lower O2.
Why shouldn’t hydrocarbons such as lubricants be used around the delivery system?
It is an oxidizing gas. Can ignite the hydrocarbons if there are rapid changes in pressure.
Molecular weight and specific gravity of N2O.
44
1.58 (Heavier than N2 and O2.
Blood Gas Partition Coefficient
Difference in partial pressures between gas and liquid. Determines how quickly it crosses the pulmonary membrane and enters the blood stream. If a drug is insoluble it will reach a equilibrium quickly and it will cross the BBB quickly/rapid onset.
What is N2O blood gas coefficient?
0.47
31 times that of N2.
Is N2O stored in the body?
Nope! Tissues don’t hold the N2O.
What is the concentration effect?
High concentration alveolar partial pressures are reached rapidly with little decrease in the concentration of the gas. Negative pressure pull more gas into the lungs. Less effect at analgesic doses.
What is the second gas effect?
With high concentrations causing rapid uptake, there is a simultaneous effect of increasing uptake of a second gas. This second gas uptake occurs faster than it normally would.
Minimum Alveolar Concentration
Amount of drug necessary to prevent movement in 50% of individuals with surgical stimulation.
What is the least potent of all anesthetic gases?
N20! MAC is 104%
What is the mechanism of action of N2O?
Opioid receptors.
Where does elimination of N20 Occur?
Primarily through the lungs. Recovery in 3-5 min. Not metabolized in the liver/GI tract.
How does barometric pressure changes affect N2O?
Need a slight increase in N2O concentration to obtain the same effects as sea level.
What are some uses of N2O?
Hospitals, food industry, auto racing, airbags, computer, ambulatory health settings, etc.
How does N2O provide synergistic effects?
Sedative and hypnotic agents. Reduces the does of the primary anesthetic agents required.
Nitrous oxide transport and cost.
Inexpensive, but potentially dangerous to transport.
What color is N2O?
Blue
What color is CO2?
Grey
What color is O2?
Green
When does the dial drop in the gas tank with nitrous as opposed to O2?
O2: drops proportionally with use. 2000 psi
Nitrous: Dial does not drop until tank is nearly empty. 750 psi
Pin Index Safety System
Prevents inadvertent attachment of N2O cylinder to O2 yoke site.
Diameter Index Safety System
Prevents inadvertent attachment of N2O hose to O2 outlet.
Min/Max O2 and N2O.
Min O2: 30%
Max N2O: 70%
O2 Failsafe mechanism
Provides automatic termination of N2O flow if O2 supply inadequate or depleted.
Oxygen Flush Valve
Provides rapid delivery of 100% O2 when needed. Replaces admixture of gasses in reservoir bag with 100% O2.
What does the Audible Alarm signal?
O2 failure. N2O failure. Located on unit or other location.
How does N2O affect the Cardiac System.
Does not negatively affect. May be slightly cardiotonic. Positive effect on myocardial ischemia by providing O2. Lower BP as a result of relaxation. Doesn’t have measurable effects on lowering BP or cardiac output.
How does N2O affect the respiratory system?
Minimal sedation. Doesn’t suppress the resp. rate. Airway patency is mandatory for adequate administration. Doesn’t decrease protective reflexes. Emphysema and chronic bronchitis appear to have increase susceptibility to hypoxia. Decreases the hypoxic drive.
How does N2O affect the CNS?
Can effect cerebral blood flow, ICP, cerebral blood velocity, cerebral perfusion pressure and O2 consumption. Less effect than other inhaled anesthetics. Little concern when used in ambulatory setting. Can affect EEG in dose dependent manner. pneumocephalus can result in increased intracranial pressure. Can see ataxic gait with chronic exposure.
How does N2O affect the hematopoetic system?
Chronic exposure leads to megaloblastic bone marrow changes. Use with caution with pt.s with vit B12 deficiency.
How does N2O affect the endocrine system?
No negative effects
How does N2O affect the hepatic system?
No effects
How does N2O affect the GI tract?
Can expand gas containing areas in the GI system. Potential nausea.
How does N2O affect the genitourinary system?
No negative effects.
How does N2O affect the reproductive system?
Avoid during the first trimester.
How does N2O affect the neuromuscular system?
Relaxes musculature indirectly. No effect on pts with neuromuscular conditions.
Are there allergic reactions to N2O?
No.
How does N2O affect pts recieving bleomycin sulfate for cancer treatment?
Can increase pulmonary fibrosis.
Is N2O a trigger for malignant hyperthermia?
No.
What nutritional disorders are affected by N2O?
Vitamin B12 deficiencies.
What are absolute contraindications for N2O?
Pneumothorax, cystic fibrosis, chronic obstructive pulmonary disease, recent pneumoencephalography, pernicious anemia or vitamin B12 deficiency, bowel obstruction, first trimester of pregnancy, cancer therapy using bleomycin sulfate, psychological impairment, current psychotropic drug use, current or recovering drug use/addiction, pt in shock, semi-conscious or with serious head/facial injuries, consent.
What are some relative contraindications?
Current upper respiratory tract infection. Middle ear disturbance/surgery. Recent eye surgery using perfluopropane or sulfur hexafluoride.
What are the appropriate sedation symptoms?
Light headedness, tingling hands/feet, wave of warmth, numbness hands/feet, euphoria, feeling of lightness/heaviness of extremities, analgesia.
Appropriate sedation signs?
BP/HR-initial rise from baseline. Respirations normal/smooth. Peripheral vasodilations, flushing. Decreased muscle tone.
Mild oversedation symptoms
Hearing more acute, confused visual images, sleepiness, laughing/crying, dreaming, nausea.
Mild oversedation signs
Movement, HR, BP, sweating, lacrimation
Profound oversedaton symptoms
Spontaneous mouth breathing, closing of mouth, complaints of nausea, uneasiness and too intense an experience.
Profound oversedation signs
Failure to respond rationally, sleepiness/dreaminess, incoherent speech, uncooperative, laughing/crying/giddy, uncoordinated movements
What discharge criteria?
Vital signs and tests of recovery. Record what you did, what you gave, condition upon discharge, post op instructions, give pt written instructions.
What is diffusion hypoxia?
Capillary tension quickly rises to that above alveolar pressure and N2O is quickly forced into the alveoli and exhaled through the lungs. N2O exits faster than the N2 that replaces it, diluting the supply of O2, and O2 blood saturation is reduced.
How does chronic exposure to high levels shown to affect DNA synthesis and reproduction?
Concern for fetal development, concern for those with poor wound healing, heatopoietic changes. First trimester has need for folic acid for organogenesis.
Myeloneuropathy
Myelin degeneration. Exhibits as a sensory and proprioception abnormalities. May be permanent but usually temporary with slow recovery.
How does inactivation of vitamin b12 affect it?
Methionine synthetase is necessary for DNA production. It catalyzes the methylation of homocysteine to methionine. N2O irreversibly oxidizes the colbalt atom of the cofactor vit. B12 cobalamin, inhibiting the activity of the cobalamin-dependent enzyme. Methionine is the pricinciple substrate for methylation in many biochemical reactions including assembly of the myelin sheath, methyl substitutions in neurotransmitters and DNA synthesis in rapidly proliferating tissues.
Clinical effects of methionine deficiency
Less methionine inhibits DNA synthesis which creates problems with hematopoiesis. Long term exposure leads to peripheral neuropathy. In most cases full recovery of the methionine deficiency occurs over several days following administration.
How many hours is needed for a lasting affect on hematopoiesis?
6 hours.
What leads to post op myocardial ischemia
Acute increases in plasma homocysteine, leading to impaired endothelial function and procoagulant effects.
What does scavenging do?
Minimizing trace amounts of gas, removing exhaled gas.
What is the suction flow rate?
45 L/Min
