ANESTHETICS

LOCAL ANESTHETICS

·         These substances induces a temporary loss of sensation in a specific body parts or region by blocking action potential propagation along neural axons

·         Indication:

o    Symptomatic relief of pain (analgesic effect) from minor surface irritation or injury (e.g minor burns, abrasions, inflammation)

o    Minor surgical procedures (e.g circumcision, wound cleansing, myringotomy, suturing)

o    Chronic pain management

·         Contraindication: known hypersensitivity to the substance

·         Methods of administration

o    Tropical

§  Applied directly to the surface of the skin, mucous membrane, cornea & other regions

o    Infiltration anesthesia

§  The drug is injected directly into the selected tissue and allowed  to diffuse to the sensory nerve endings within the tissue

o    Peripheral nerve block

§  The drug is injected close to the nerve trunk

o    Central nerve block

§  The drug is injected within the spaces surrounding the spinal cord (e.g subarachnoid space).

o    Sympathetic ganglion injection

Generic names	Brand names
benzocaine	Oragel®, Americaine® *T
buvivacaine	Marcaine®, Vivacaine® *I, PNB, CNB,SB
butamben	Butesin Picrate® *T
chloroprocaine	Nesacaine® *I, PNB,CNB
dibucaine	Nupercainal® *T
etidocaine	Duranest® *I, PNB, CNB
lidocaine	Xylocaine® *T, I, PNB, CNB, SB
mepivacaine	Carbocaine® *T, I, PNB, CNB
pramoxine	Dermoplast®, Tronothane® *T
prilocaine	Catinest® *I, PNB
procaine	Novocain® *I, PNB, SB
tetracaine	Pontocaine® *T, CNB

* T - topical; PNB - peripheral nerve block; CNB - central nerve block; SB - sympathetic block

GENERAL ANESTHETICS

·         Drugs that depress the central nervous system, alleviate pain, inhibit the autonomic reflexes, relax skeletal muscle and cause loss of consciousness.

Stages of General Anesthesia:

I. Analgesia	Patient begins to lose somatic sensation. He is conscious and somewhat aware of what is happening.
II. Excitement (delirium)	Patient loses consciousness which is caused by depression of the cerebral cortex. Patient may appear agitated and restless. Efforts should be made to move the patient to the next stage as soon as possible to avoid injury.
III. Surgical anesthesia	Surgical procedure is performed at this stage.  Respiration becomes shallow and rapid (tachypnea).
IV. Medullary paralysis	Respiration is lost and circulatory collapse occurs due to the cessation of the medullary respiratory and vasomotor control centers as inhibited by the anesthetic substance. Ventilatory assistance is indicated.

Inhalation Anesthetics

·         This method of administering general anesthetic substances is usually performed during the third (3rd) stage of anesthesia.

·         Most of the currently used inhaled anesthetics are in halogenated volatile liquid state. The only gaseous anesthetic that is widely used today is nitrous oxide and is usually used for relatively short-term procedures (e.g tooth extractions).

Drug	Induction	Recovery
methoxyflurane (Penthrane®)	Slow	Recovery of unconsciousness: 1 hour after cessation of drug administration.
halothane (Fluothane®)	Rapid
enflurane (Ethrane®)	Rapid
isoflurane (Forane®)	Rapid
sevoflurane (Ultane®)	Rapid	Recovery of unconsciousness: within minutes after cessation of drug administration.
desflurane (Suprane®)	Rapid
Nitrous oxide "laughing gas"	Rapid

·         n.b Usaully combined with: barbiturate (thiopental), strong analgesic (morphine), muscle relaxant (pancuronium).

·         Use of succinylcholine, a depolarizing muscle relaxant, with inhaled anesthetics predisposes patient to malignant hyperthermia.

·         Malignant hyperthermia is an inherited myopathy characterized by a hypermetabolic state which is triggered when the patient is exposed to some anesthetic agents.

Contraindications:

·         Halothane, enflurane & isoflorane are contraindicated in obstetrics unless uterine relaxation is desired.

·         Eflurane should not be given to patients with seizure disorders

Intravenous Anesthetics

Drugs
Barbiturates: o thiopental (Pentothal®) o methohexical o thiamylal	§ It has a rapid-acting effect once administered intravenously and is relatively safe if used appropriately. § It potentiates the effects of GABA therefore decreases the level of arousal.
droperidol (Innovar®)	§  Droperidol and fentanyl combination induces neuroleptanalgesia which is characterized by dissociation of the patient from what is happening around him with or without loss of consciousness.
etomidate (Amidate®)	§ A hypnotic-like drug that causes a rapid onset of general anesthesia with minimum cardiorespiratory side effects § Mimics the inhibitory effects of GABA
ketamine hydrochloride (Ketalar®)	§ Induces dissociative anesthesia. Useful during relatively short diagnostic or surgical procedures (endoscopy, burn dressing) or during invasive procedures in children § Binds to N-methyl-D-aspartate receptor in the brain  and thus inhibiting the excitatory effects of glutamate

Commonly administered for the induction and maintenance of anesthesia or conscious sedation for minor surgery or procedures:

Drugs
Benzodiazepines: o midazolam o diazepam o lorazepam	§  It potentiates the effects of GABA and depresses neuronal excitability therefore induces general anesthesia/decreases the level of arousal.
Propofol (Diprivan®)	§  It can also be used as a short-acting hypnotic that is useful as a general anesthetic in short-invasive procedure. §  Recovery is more rapid as compared with other anesthetics.
Opioid analgesics fentanyl morphine meperidine	§  It decreases transmission of nociceptive pathways by binding to specific neuronal receptors in the brain and spinal cord.

Balanced Anesthesia

·         Frequently used in general anesthesia because it has fewer adverse reactions as compared to large doses of general anesthesia.

·         Balance anesthesia generally includes:

o    Narcotic analgesic: butorphanol (Stadol^®)

o    Benzodiazepine: midazolam (Midazolam Injection^®)

o    Anticholinergic: atropine

o    Short-acting barbiturate: thiopental sodium (Pentothal^®)

o    Nitrous oxide

o    Muscle relaxant (e.g succinylcholine: Anectine^®)

Advantages of balance anesthesia:

·         Minimizes cardiovascular problems

·         Decreases the amount of general anesthetic needed

·         Reduces possible postanesthetic nausea & vomiting

·         Minimizes the disturbance of organ function

·         Increases recovery from anesthesia

Nursing Consideration:

·         Constant monitoring of VS is imperative for patients administered with anesthetics. Respiratory and cardiovascular distress (e.g hypotension, dysrhythmias, malignant hyperthermia) may occur.

·         Monitor patient's state of sensorium after operation. Notify physician if patient remains unresponsive or confused for a time.

·         Monitor urine output and report deficits

·         Patients with large deposits of fats may take longer to washout anesthetics in the tissue. Patient may experience confusion, disorientation and lethargy. General anesthetics are highly lipid soluble and tend to get stored in adipose tissue.

·         Propofol supports microbial growth and increase the risk of bacterial infection. Discard open vials within 6 hours to prevent sepsis.

·         Have intubation supplied readily available.

TEST TAKING STRATEGIES (NLE)

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BRONCHODILATORS

·         Used to prevent or terminate bronchospasms caused by pulmonary disease, allergy, exercise, or emotional factors.

SYMPATHOMIMETIC

·         Dilate the airways of the respiratory tree, making air exchange & respiration easier, relaxing the smooth muscle

·         Indications:

o    Bronchospasm associated with acute and chronic bronchial asthma, exercise-induced bronchospasm, bronchitis, emphysema, bronchiectasis, other obstructive pulmonary diseases

·         Contraindications:   

o     Hypersensitivity to the drug, cardiac arrhythmias, associated with tachycardia, organic brain damage, cerebral arteriosclerosis, narrow-angle glaucoma

o    Long acting not used alone to control

Example: (Bronchodilators: Sympathomimetics)

albuterol (Ventolin®)

ephinephrine  (Adrenalin®)

salmeterol (Serevent®)

terbutaline sulfate (Brethine®, Bricanyl®, Brethaire®)

metaproterenol sulfate (Medihaler-Iso®)

Adverse Reactions:

·         Tachycardia, palpitations, or cardiac arrhythmias

·         Nervousness, anxiety

·         Hypertension

·         Insomnia

Nursing Considerations:

ü  Assess the respiratory status before and after each dose.

ü  During attack or to prevent attack use albuterol as a rescue drug.

ü  To control asthma daily use salmeterol long acting.

ü  Wait at least one minute between puffs, use spacer.

XANTHINES

·         Stimulate the central nervous system, respiration, dilate coronary & pulmonary vessels, cause diuresis, and relax the smooth muscle

·         Indications:

o    Bronchospasm associated with acute and chronic bronchial asthma, allergic rhinitis, sinusitis

·         Contraindications:   

o    Hypersensitivity to the drug, peptic ulcer disease, severe cardiac disease or dysrhythmias, hyperthyroidism, chronic obstructive pulmonary disease, emphysema

Example: (Bronchodilators: Xanthines)

aminophylline (Truphylline®, Phyllocontin®)

theophylline (Aerolate®, Slo-Phyllin®, Theolair®)

theophylline (Theo-Dur®, Slo-Bid®, Theo-24®, Uni-Dur®, Uniphyl®)

oxtriphylline ( Choledyl®, Choledyl- SA®)

Adverse Reactions:

·         Anorexia	·         Nausea, vomiting
·         Gastric pain	·         Hypotension
·         Hyperreflexia	·         Seizures
·         Tachycardia, palpitations, cardiac dysrhythmias

 Nursing Considerations:

ü  Do not dissolve, crush, or chew enteric –coated or sustained-release products.  

ü  Follow instructions for drug administration and dosage schedule.

ü  Take the drug regularly and with a full glass of water.

ü  For a patient who can’t swallow the whole pill, sprinkle its contents over soft foods.

ü  Provide precautions and slowly administer IV aminophylline or theophylline preparations, or always an infusion pump.

ü  Teach the patient who missed a dose or vomits shortly after taking a dose to consult physician for instructions.

ü  Change position slowly and avoid hazardous activities during drug therapy.

ü  Avoid caffeine products such as coffee, tea, cola, and chocolate.

ü  Advise the patient to stop smoking and provide information regarding support resources.

ü  Monitor for a therapeutic serum theophylline level of 10-20 mg/mL. Note that toxicity is likely to occur when the serum is greater than the normal value. Notify physician if this occurs.

LEUKOTRIENES

·         Bronchoconstrictive substances released by the body during the inflammatory process wherein when production is inhibited, bronchodilation is facilitated.

·         Indications:

o    (Zileuton & montelukast): used in the prophylaxis and treatment of chronic asthma in adults and children older than 12 years old

o    (Zafirlukast): used in the prophylaxis and treatment of chronic asthma in adults and in children older than 5 years old

·         Contraindications:   

o    Hypersensitivity, bronchospasm in acute asthma attacks, or liver disease, pregnancy, lactation

Leukotriene Receptor Antagonists	Leukotriene Formation Inhibitors
montelukast sodium (Singulair®)	zileuton (Zyflo®)
zafirlukast (Accolate®)

Adverse Reactions:

·         Headache, dizziness	·         Nausea, vomiting
·         Dyspepsia	·         Flu symptoms, cough
·         Diarrhea, abdominal pain

Nursing Considerations:

ü  Assess for wheezing, decreased breath sounds, cough and sputum production.

ü  Monitor vital signs and instruct patient how to monitor pulse rate.

ü  Maintain adequate hydration.

ü  Administer zafirlukast 1 hour before or 2 hours after meals for best absorption while montelukast is best absorbed when given at night.

ü  Encourage the use of rescue medication for acute attacks or when a short acting inhaled medication is needed but avoid to taking OTC preparations without prescription.

ü  Stress the importance of continuous use of the prescribed drug for optimal effects.

MAST-CELLS STABILIZERS

·         Mechanism of action is not fully understood, but these drugs are thought to stabilize the mast cell membrane, possibly preventing calcium ions from entering mast cells, therefore, hindering the release of inflammatory mediators.

·         Indications:

o    Used in combination with other drugs in the treatment of asthma and allergic disorders, rhinitis

·         Contraindications:   

o    Hypersensitivity to the drugs, asthma, pregnancy, lactation, patients with impaired renal or hepatic function

       

Example:

cromolyn Sodium (Intal®)

nedocromil (Tilade®)

Adverse Reactions:

·         Headache

·         Pharyngeal, trancheal irritation 

·         Wheezing, bronchospasm, cough

Nursing Considerations:

ü  Monitor respiratory status before therapy and regularly thereafter.

ü  Avoid use of these drugs for reversing bronchospasm during an acute asthma attack.

ü  Monitor for adverse effects of therapy.

ü  Notify physician if condition worsens.

ANTIHISTAMINES (histamine antagonists or H₁ blockers)

·         Prevent histamine from binding to histamine (H1) receptors, thereby blocking the histamine reaction.

·         Indications:

o    Relief of symptoms of seasonal and perennial allergies, common colds, allergic & vasomotor rhinitis, allergic conjunctivitis, mild and uncomplicated angioneurotic edema, urticaria, adjunctive therapy in anaphylactic shock, treatment of parkinsonism, nausea, vomiting , motion sickness, sleep aid, and adjuncts to analgesics

·         Contraindications:   

o    Hypersensitivity, severe liver disease, narrow-angle glaucoma, pregnancy, newborn or premature infant, breastfeeding, angle-closure glaucoma, stenosing peptic ulcer,  urinary retention, patients undergoing monoamine oxidase inhibitor therapy

(First-Generation Antihistamines)

astemizole ( Hismanal®)

azatadine maleate (Optimine®)

bronpheniramine maleate (Dimetane®)

chlorpheniramine maleate ( Aller-Chlor®, Chlor-Trimeton®)

clemastine fumarate ( Tavist ®)

cyproheptadine hydrochloride (Periactin®)

diphenhydramine (Benadryl ®)

doxylamine succinate (Unisom®)

methdilazine hydrochloride (Tacaryl®)

pyrilamine maleate (Nisaval®)

trimeprazine tartrate (Temaril®)

(Second-Generation Antihistamines)

ceritizine hydrochloride ( Zyrtec®)

azelastine hydrochloride (Astelin®)

fexofenadine (Allegra®)

loratadine (Claritin®)

desolaratidine (Larinex®)

Side Effects:

·         Drowsiness, dizziness	·         Fatigue
·         Constipation	·         Blurred vision
·         Skin rashes	·         Disturbed coordination
·         Photosensitivity	·         Dry mouth
·         Urinary retention	·         Wheezing
·         Nervousness, irritability

Nursing Considerations:

ü  Monitor vitals signs & urinary dysfunction.

ü  Administer with food to decrease gastric distress.

ü  Avoid subcutaneous (SC) injection and administer intramuscularly in a large muscle if it is prescribed.

ü  Avoid alcohol and other central nervous system depressants.

ü  Do not drive or perform any hazardous activities if drowsiness occurs.

ü  For motion sickness, take the drug at least 30 minutes before the event, and then before meals and at bedtime during the event.

ü  Provide hard candy, or ice chips to suck on for dry mouth.