Exam 1 Flashcards
Pain
An unpleasant sensory and emotional experience associated with or resembling that associated with actual or potential tissue damage
Components of Pain
Perception
Physical component, message of pain carried through the nerves to the cortex, transmitted as an impulse, can be affected by disease
Components of Pain
Reaction
Psychologic component, patients emotional response, varies greatly
Pain Threshold
Point of increasing perception of a stimulus at which pain begins to be felt by the individual, interpretation of the stimulus, varies greatly
Decreased Pain Threshold
Greater reaction to pain. Anxiety, fatigue, youth, female gender, fear
Increased Pain Threshold
Reduced reaction to pain. Sleep, sympathy, actitivies
Fear and Anxiety
Fear= an emotion induced by perceived danger or threat, physiological changes
Anxiety= your body’s natural response to stress, feeling of fear about what’s to come
BOTH LOWER THE PAIN THRESHOLD
LA Pharmacologic Effects
Peripheral nerve blocker, road block for the nerve transmission, prevents brain from interpreting the impulse as pain
Membrane Expansion Theory
LA molecules diffuse to hydrophobic regions of membranes, preventing an increase in permeability to sodium ions, decreased diameter of sodium channels
Specific Receptor Theory
Most favored theory, LA act by binding to specific receptors on the sodium channel, action of the drug is direct, LA gains access to the receptors and permeability to sodium ions is decreased
Vasoactivity of LA
All anesthetic produce some level of vasodilation. Ester drugs are potent vasodilators, procaine most powerful vasodilator, cocaine vasoconstriction
Vasodilation
An increase in the rate of absorption of the LA into the blood, dresses duration and quality of pain control, increases the anesthetic blood concentration
Greatest Percentages of LA Areas in Body
Skeletal muscles
Blood level of LA Influenced by (3)
- Rate of absorption
- Rate of distribution of drug from vascular compartment to tissues. More quickly in healthy patients
- Elimination of drug through metabolic or excretory pathways
Metabolism of LA
A balance between its rate of absorption into the bloodstream and its rate of removal from the blood through tissue uptake and metabolism
Absolute Contraindication
Under no circumstance should the drug be administered as the possibility of potentially toxic or lethal reactions is increased
Relative Contraindication
Drug may be administered after weighing the risk associated with the use of the drug, smallest clinically effective dose is used
Metabolism of Ester Drugs
Hydrolyzed in the plasma by the enzyme pseudocholinesterase, procaine undergoes hydrolysis to PABA (metabolic product), allergic reactions are related to PABA not the drug itself
Atypical Pseudocholinesterase
Hereditary trait 1 in every 2,800 people, inability to hydrolyze an ester, increases toxicity potential
Relative Contradiction of Ester Drugs
Atypical pseudocholinesterase and PABA allergy
Metabolism of Amide Drugs
Biotransformation occurs in the liver, lidocaine, mepivacaine, etidocaine, and bupivacaine.
Amide Drug Prilocaine
Primary metabolism in the liver, some in the lung
Amide Drug Articaine
Contains both ester and amide components, metabolism in both the blood (primarily) and the liver
Increased Risk of Toxicity Amide Drugs
Patients with lower than normal hepatic blood flow and poor lover function. Unable to biotransform amide drug at a normal rate
Methemoglobinemia
Condition in which a cyanosis like state develops in the absence of cardiac abnormalities, blood levels become elevated with it
Relative Contraindication of Amide Drugs
Liver dysfunction ASA 4 or 5, heart failure ASA 4 or 5, methemoglobinemia (prilocaine)
Blood Level of the LA depends on (4)
Rate of uptake, rate of distribution, rate of biotransformation (in liver), processes to remove drug from blood
Anti-convulsive Level
0.5-4
Pre-seizure Signs and Symptoms
4.5-7
Signs: talkative, sweating, vomiting, elevated heart rate
Symptoms: dizziness, metallic taste, warm, sensation of twitching
Tonic-clonic Seizure
> 7.5
Signs: generalized CNS depression, depressed blood pressure, heart rate and respiratory rate
