Vasoconstrictors-Pain-1 Flashcards
All clinically effective injectable local anesthetics are
vasodilators
Local anesthetic injection into tissues results in, ______(decreased/increased ) perfusion at thesite
increased
Local anesthetic injection into tissues results in, increased perfusion at thesite, leading to the following reactions
- Increased rate of absorption into thecardiovascular system, removes it from theinjection site (redistribution)
- Higherplasmalevelsof the local anesthetic, increases in therisk of localanesthetic toxicity (overdose)
- Decrease in both the depth and duration of anesthesia because the local anesthetic diffuses away fromthe injection site more rapidly
- Increased bleeding atthe siteof treatment asa result of increased perfusion
Vasoconstrictors are important additions to a local anesthetic solution for thefollowing reasons:
- By constricting blood vessels, vasoconstrictors decreaseblood flow (perfusion) tothe site of drug administration.
- Absorption of the local anesthetic intothe cardiovascular system is slowed, resulting in lower anesthetic blood levels.
- Localanesthetic blood levelsare lowered,thereby decreasingthe risk oflocalanesthetic toxicity.
- More local anesthetic enters into the nerve, where it remainsfor longer periods,thereby increasing the duration of action (in some cases significantly, in others minimally) of most local anesthetics.
- Vasoconstrictorsdecrease bleeding at the siteof administration;therefore they are useful when increased bleeding is anticipated (e.g., during asurgical procedure)
Catecholamine
- Epinephrine
- Norepinephrine
- Levonordefrin
- Isoproterenol
- Dopamine
Non-catecholamine
- Amphetamine
- Methamphetamine
- Ephedrine
- Phenylephrine
Direct Acting Drugs
exert their action directly on adrenergic receptors
Indirect Acting Drugs
stimulate the release of the cathecholamine norepinephrine from adrenergic nerve terminals (Tachyphylaxis)
Mixed Acting
acts on both direct and indirect receptors
Activation of A receptors by a sympathomimetic drug usually produces a response that includes
contraction of smooth muscle in blood vessels (vasoconstriction).
A 1 receptors =
excitatory-postsynaptic
A 2 receptors =
inhibitory-postsynaptic
Activation of beta receptors produces ?
smooth muscle relaxation (vasodilation andbronchodilation) and cardiac stimulation (increased heart rate and strength ofcontraction).
Beta 1are found in
heart and small intestines
Beta 1are responsible for ? (slide 15)
cardiac stimulation and lipolysis;
Beta 2are found in
the bronchi, vascular beds, and uterus,
Beta 2are responsible for ? (slide 17)
produce bronchodilation and vasodilation
A concentration of1:1000means?
1 g(1000mg)of solute(drug) iscontained in 1000mL of solution.
Epinephrine concentrations used in clinical dentistry are much lower yet very effective.
T/F
T
To producea 1:10,000 concentration,1 mLof a1:1000solution is added to___mLof solvent(e.g., sterile water);
To producea 1:10,000 concentration,1 mLof a1:1000solution is added to9 mLof solvent(e.g., sterile water); therefore 1:10,000 = 0.1 mg/mL (100µg/mL)
To producea 1:100,000concentration, 1mL ofa 1:10,000concentration isaddedto___mL ofsolvent
To producea 1:100,000concentration, 1mL ofa 1:10,000concentration isaddedto 9mL ofsolvent;
therefore 1:100,000 = 0.01 mg/mL (10 µg/mL)
How much in a cartridge?
If a 1:100,000 concentration contains 0.01mg/ml and a cartridge contains 1.7 ml of solution, then:
0.01 mg/ml X 1.7 ml = .017 mg per cartridge
If you use 2 cartridges, then 2 X .017 = .034 mg
How much in a cartridge?:
If a 1:100,000 concentration contains 0.01mg/ml and a cartridge contains 1.7 ml of solution, then:
0.01 mg/ml X 1.7 ml = .017 mg per cartridge
If you use 2 cartridges, then 2 X .017 = .034 mg
epinephrine reaction
even following usual precautions (e.g., aspiration, slow injection), sufficient epinephrine can be absorbed to cause sympathomimetic reactions such as apprehension, tachycardia, sweating, and pounding in thechest (palpitation)—the so-called epinephrine reaction.
Epinephrine A or B?
- Beta effects predominate
- Epinephrine acts directly on both alpha and beta adrenergic receptors
Epinephrine»CVS?
Increased systolic Increased cardiac output (CO = HR X SV) Increased stroke volume Increased heart rate Increased strength of contraction Increased myocardial oxygen consumption
Rebound Bleeding»>Epinephrine
- Due to predominantly alpha receptor stimulation, and hemostasis.
- As levels decrease over time, its primary action on blood vessels reverts to vasodilation because beta 2 actions predominate; (Rebound Bleeding)
- Post Extraction bleeding occurred in 13 of 16 patients receiving epinephrine with their local anesthetic for hemostasis
Small doses of epinephrine produce ?
dilation of these vessels as a result of beta 2actions. Beta 2receptors are more sensitive to epinephrine than are alphareceptors.
Large doses of epinephrine produce ?
Larger doses produce vasoconstriction because alpha receptors are stimulated
epinephrine»_space; primary action on smaller arterioles and precapillary sphincters
Produces constriction in the vessels supplying the skin, mucous membranes, and kidneys primarily contain alphareceptors.
Epinephrine is a potent ______ (constrictor/dilator) (beta 2 effect) of bronchiole smooth muscle
Epinephrine is a potent dilator (beta 2 effect) of bronchiole smooth muscle
Epi is an important drug for management of more refractory episodes of bronchospasm (e.g., status asthmaticus) _______ ?
potent dilator (beta 2 effect) of bronchiole smooth muscle.
Epinephrine _______ (increases/decreases) oxygen consumption in all tissues.
Epinephrine increases oxygen consumption in all tissues.
Epinephrine that escapes reuptake is rapidly inactivated in the blood by the enzymes ______ and ______, both of which are present in the liver.
catechol-O-methyltransferase (COMT) and
monoamine oxidase (MAO)
Epinephrine» Clinical Applications:
Acute allergic reactions Bronchospasm Cardiac arrest Vasoconstrictor for hemostasis Vasoconstrictor for local anesthetics To produce mydriasis
Epinephrine»Side Effects and Overdose
CNS stimulation increases fear, anxiety, tension, restlessness, headache, tremor, weakness
Cardiac dysrhythmias
Increased systolic blood pressure
Angina
In patients with _____, norepinephrine may account for up to 80% of adrenal medullary secretions.
pheochromocytoma (tumor of the adrenal medulla, )
Norepinephrine is ____as potent as epinephrine
1/4 th
Norepinephrine receptors? A/b?
- The actions of norepinephrine are almost exclusively on alphareceptors (90%).
- It also stimulates beta actions in the heart (10%).
Norepinephrine CVS effects?
Decreased heart rate Increased systolic pressure Increased diastolic pressure Unchanged or slightly decrease cardiac output Increased stroke volume Increased total peripheral resistance
Norepinephrine _______ (does/does not ) relax bronchial smooth muscle, as does epinephrine
Norepinephrine does NOT relax bronchial smooth muscle
Norepinephrine is clinically effective in the management of bronchospasm. T/F?
F.
Norepinephrine is NOT clinically effective in the management of bronchospasm.
Norepinephrine ______ (increases/decreases) the basal metabolic rate
increases BMR
Tissue oxygen consumption is also increased in the area of injection. Norepinephrine produces an elevation in the blood sugar level in the same manner as epinephrine, but to a lesser degree.
The degree and duration of ischemia noted after norepinephrine infiltration into the palate have led to soft tissue necrosis. Why?
Norepinephrine, through alphastimulation, produces constriction of cutaneous blood vessels. This leads to increased total peripheral resistance and increased systolic anddiastolic blood pressures
Norepinephrine: Side Effects and Overdose
-Excessive levels of norepinephrine in the blood produce markedly elevated systolic and diastolic pressures with increased risk of hemorrhagic stroke, headache, anginal episodes in susceptible patients, and cardiac dysrhythmias
-Extravascular injection of norepinephrine into tissues may produce necrosis and sloughing because of intense alpha stimulation.
In the oral cavity, themost likely site is hard palate. Norepinephrine should be avoidedfor vasoconstricting purposes (e.g., hemostasis), especially on the palate.
Clinical Applications of Norepinephrine:
It is used as a vasoconstrictor in local anesthetics and for the management of hypotension.
Levonordefrin: Side Effects and Overdose
hypertension, ventricular tachycardia, and anginal episodes in patients with coronary artery insufficiency
Max dose of Levonordefrin
For all patients,the maximum dose should be 1 mg per appointment; 20 mL of a 1:20,000 dilution (11 cartridges).
Phenylephrine Hydrochloride: A/B?
Direct alpha receptor stimulation occurs (95%). Although the effect is less thanwith epinephrine, duration is longer.
Phenylephrine exerts little or no beta action on the heart. Only a small portion of its activity results from its ability to release norepinephrine.
Phenylephrine is only5% as potent as epinephrine.
Phenylephrine Hydrochloride: Applications?
Phenylephrine is used as avasoconstrictor in local anesthetics, for the management of hypotension, as a nasal decongestant, and inophthalmic solutions to produce mydriasis.
Two vasoconstrictors are available in local anesthetic solutions in North America:
epinephrine and levonordefrin.
Selection Criteria for aVasoconstrictor
- the length of the dental procedure
- the need for hemostasis during and following the procedure.
- the requirement for post operative pain control
- medical status of the patient
Addition of any vasoactive drug prolongs the duration (and depth) of pulpal and soft tissue anesthesia of most local anesthetic
: T/F
T
Epinephrine and other vasoconstrictors cannot be administered, within limits, to patients with mild to moderate cardiovascular disease (ASA2 or 3): T/F
F: Can be
______ vasocontrictor may be used for ASA3 or 4 cardiovascular risk patient
felypressin
Because felypressin has minimum cardiovascular stimulatory action and is non-dysrhythmogenic
Administration of ___ or ______ is absolutely contraindicated in patients receiving tricyclic antidepressants.
levonordefrin or norepinephrine»> absolutely contraindicated»_space;>tricyclic antidepressants.
Large doses of vasoconstrictor may induce severe (exaggerated) responses.
