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Diabetes Insipidus

 

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Diabetes insipidus is a disorder of the posterior lobe of the pituitary gland due to a deficiency of vasopressin, the antidiuretic hormone (ADH). it is characterized by polydipsia and polyuria. Diabetes insipidus may be (1) secondary, related to head trauma, brain tumor, or surgical ablation or irradiation of the pituitary gland or infection of the central nervous system or metastatic tumors (lung or breast); (2) nephrogenic (faliure of the renal tubules to respond to ADH), possibly related to hypokalemia, hypercalcemia, and a variety of medications (eg, lithium, demeclocycline); (3) primary (hereditary), with symptoms possibly beginning t birth (defect in pituitary gland).

The disease cannot be controlled by limiting the intake of fluids because loss of high volumes of urine continues even without fluid replacement. Attempts to restrict fluids cause the patient to experience an insatiable carving for fluid and to develop hypernatremia and severe dehydration.

Clinical Manifestations

  • Polyuria: enormous daily output of very dilute urine (specific gravity 1.001 to 1.005). Primary diabetes insipidus may have ab abrupt onset or an insidious onset in adults.
  • Polydipsia: patient experiences intense thirst, drinking 2 to 20 liters of fluid daily, with a special craving for cold water.
  • Polyuria continues even without fluid replacement.

Assessment and Diagnostic Findings

  • Fluid deprivation test: fluids are withheld for 8 to 12 hours until 3% to 5% of the body weight is lost. Inability to increase specific gravity and osmolality of the urine during test is characteristic of diabetes insipidus.
  • Urine specific gravity, serum osmolality, and serum sodium levels may be obtained.

Medical Management

Objectives of the therapy are to ensure adequate fluid replacement, to replace vasopressin, and to search for and correct the underlying intracranial pathology. Treatment for diabetes insipidus of nephrogenic origin involves using thiazide diuretics, mild salt depletion, and prostaglandin inhibitors (eg. ibuprofen, indomethacin, and aspirin).

Vasopressin Replacement

  • Desmopressin (DDAVP), administered intranasally, 1 or 2 administrations daily to control symptoms.
  • Lypressin (Diapid), absorbed through nasal mucosa into blood; duration may be short for patients with severe disease.
  • Intramuscular administration of ADH (vasopressin tannate in oil) every 24 to 96 hours to reduce urinary volume (shake vigorously or warm; administer in the evening, rotate injection sites to prevent lipodystrophy)

Fluid Conservation

  • Clofibrate, a hypolipidemic agent, has an antidiuretic effect on patients who have some residual hypothalamic vasopressin.
  • Chlorpropramide (Diabinese) and thiazide diuretics are used in mild forms to potentiate the aciton of vasopressin; may cause hypoglycemic reactions.

Nursing Management

  • Encourage and support patient undergoing studies for possible cranial lesion.
  • Instruct patient and family members about follow-up care and emergency measures.
  • Advise patient to wear a medical identification bracelet and to carry medication information about the disorder at all times.
  • Use caution with administration of vasopressin if coronary artery disease is present because of vasoconstrictive action of this drug.

 

Reference:

Joyce Young Johnson et. al Handbook for Brunner & Suddarth’s Textbook of Medical-Surgical Nursing 11th edition

Lippincott Williams & Wilkins pp.297-299

 

 

 

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Introduction to Nerves and the Nervous Systems

Introduction to Nerves and the Nervous System

Role of the Nervous System

  • Controls the functions of the human body
  • Analyzes incoming stimuli
  • Integrates internal and external responses

Makeup of the Nervous System

  • Central nervous system (CNS)
    • Composed of the brain and spinal cord
  • Peripheral nervous system (PNS)
    • Sensory receptors bring information into the CNS
    • Motor nerves carry information away from the CNS
  • Autonomic nervous system (ANS)
    • Uses components of the CNS and PNS to regulate automatic or unconscious responses to stimuli

Functions of the Cells That Make Up the Nervous System

  • Allow movement
  • Allow realization of various sensations
  • Provide response to internal and external stimuli
  • Stimulate learning, thinking, and emotions

Neuron

Neuron
Neuron

 

 

Types of Axons

  • Afferent fibers
    • Nerve axons that run from peripheral receptors into the CNS
  • Efferent fibers
    • Nerve axons that carry nerve impulses from the CNS to the periphery to stimulate muscles or glands

Action Potential

Action Potential
Action Potential

 

 

Electrolytes Involved in Nerve Cell Action

  • Sodium
  • Potassium
  • Calcium

Movement of Electrolytes With Action

  • Rest/repolarization
    • Membrane is impermeable to sodium
    • Membrane is permeable to potassium
  • Action/depolarization
    • Sodium goes into the cell
    • Potassium leaves the cell

Formation of Myelin Sheath

Formation of Myelin Sheath
Formation of Myelin Sheath

 

 

Nerve Synapse

  • Presynaptic nerve
  • Synaptic cleft
  • Postsynaptic effector cell

Neurotransmitters

  • Acetylcholine
    • Communicates between nerves and muscles
  • Norepinephrine and epinephrine
    • Catecholamines released by nerves in the sympathetic branch of the ANS
  • Dopamine
    • Involved in the coordination of impulses and responses
  • Gamma-aminobutyric acid (GABA)
    • Inhibits nerve activity and is important in preventing overexcitability or stimulation such as seizure activity
  • Serotonin
    • Important in arousal and sleep and in preventing depression and promoting motivation

Central Nervous System

  • Made up of brain and spinal cord
  • Structures are covered by meninges
  • Blood–brain barrier
  • Blood supply to the brain

Anatomy of the Brain

Anatomy of the Brain
Anatomy of the Brain

 

 

Hindbrain

  • Runs from the top of the spinal cord into the midbrain
  • Most primitive part of the brain: contains the brain stem
  • Controls basic vital functions:
    • Breathing
    • Blood pressure
    • Swallowing
    • RAS

Midbrain

  • Contains the thalamus, the hypothalamus, and the limbic system
    • The thalamus sends direct information into the cerebrum to transfer sensations
    • The hypothalamus acts as the major sensor of activity in the body
      • Temperature regulation
      • Water balance
      • Appetite
      • Endocrine function

Limbic System

  • Contains high levels of the neurotransmitters:
    • Epinephrine
    • Norepinephrine
    • Serotonin
  • Controls expression of emotions

Forebrain

  • Made up of 2 cerebral hemispheres joined together by the corpus callosum
  • Receives and sends nerve impulses, coordinates speech and communication, and facilitates learning

Spinal Cord

  • Made up of 31 pairs of spinal nerves
  • Each spinal nerve has 2 components or roots
    • Sensory fiber (dorsal root)
      • Brings information into the CNS from the periphery
    • Motor fiber (ventral root)
      • Causes movement or reaction

Functions of Central Nervous System

  • Sensory functions
  • Motor functions
  • Intellectual and emotional functions

Intellectual and Emotional Function

  • Two hemispheres of the brain process information differently
  • Right side
    • Artistic
  • Left side
    • Analytical
  • When learning takes place, an actual change occurs in a neuron
  • Some degree of stress facilitates learning
  • Increased stress inhibits learning
  • The limbic system plays a role in learning
  • Emotions associated with memory and the present have an impact on stimulus response
Categories
Chemotherapeutic Agents Nursing Pharmacology

Immune Modulators

Immune Modulators

 

Sites of Actions of Immune Modulators

  • Immune modulators
    • Modify the actions of the immune system
  • Immune stimulants
    • Energize the immune system when it needs help fighting a specific pathogen
  • Immune suppressants
    • Block the normal effects of the immune system in organ transplantation and autoimmune disorders

Immune Stimulants

  • Interferons
    • Naturally released from human cells in response to viral invasion
  • Interleukins
    • Communicate between lymphocytes, stimulate cellular immunity, and inhibit tumor growth
  • T and B cell modulator (levamisole)
    • Restores immune function and activity

Interferon

  • Actions
    • Prevents virus particles from replicating inside other cells
    • Stimulates interferon receptor sites on noninvaded cells to produce antiviral proteins
    • Inhibits tumor growth and replication
  • Pharmacokinetics
    • Absorbed well after subcutaneous or intramuscular injection
    • Broken down in the tissues
    • Excreted in the kidneys
    • May be teratogenic
  • Contraindications
    • Known allergy
    • Pregnancy and lactation
    • Use with caution in cardiac disease, myelosuppression, and with central nervous system dysfunction
  • Adverse reactions
    • Lethargy, myalgia, arthralgia, anorexia, nausea, headache, dizziness, and bone marrow depression
  • Drug-to-drug interactions

Interleukins

  • Definition
    • Chemicals produced by T cells to communicate between leukocytes
  • Types of preparations
    • Aldesleukin (Proleukin)
      • Human interleukin produced by recombinant DNA technology using Escherichia coli bacteria
    • Oprelvekin (Neumega)
      • A newer agent produced by DNA technology
  • Actions
    • Increase the number of natural killer cells and lymphocytes
    • Activate cellular immunity and inhibit tumor growth
  • Indications
    • Aldesleukin: specific renal carcinomas and possible treatment of AIDS and AIDS-related disorders
    • Oprelvekin: prevention of severe thrombocytopenia after myelosuppressive chemotherapy
  • Pharmacokinetics
    • Rapidly distributed after injection
    • Cleared by the kidneys
    • Teratogenic
  • Contraindications
    • Known allergy, pregnancy, and lactation
    • Caution with renal, liver, or cardiovascular impairment
  • Adverse reactions
    • Lethargy, myalgia, arthralgia, fatigue, fever, and respiratory difficulties

T and B Cell Modulators

  • Action/Indication
    • Levamisole stimulates B cells which in turn stimulate antibody formation, enhancing T cell activity
    • Used in the treatment of Duke’s stage C colon cancer
  • Pharmacokinetics
    • Absorbed from the GI tract
    • Peaks in 1.5 to 2 hours
    • Metabolized in the liver and excreted in the urine
    • T½ of 16 hours
  • Contraindications
    • Known allergy, pregnancy, and lactation
  • Adverse reactions
    • Headache, dizziness, ataxia, nausea, vomiting, and diarrhea
  • Drug-to-drug interactions
    • Disulfiram-type reaction
    • Increased phenytoin levels

Types of Immune Suppressants

  • T and B cell suppressors
  • An interleukin receptor antagonist
  • Monoclonal antibodies
    • Produced by a single clone of B cells that react with specific antigens

T and B Cell Suppressors

  • Azathioprine (Imuran): prevents rejection in renal hemotransplants; treats rheumatoid arthritis
  • Cyclosporine (Sandimmune): suppresses rejection in a variety of transplants; treats rheumatoid arthritis and psoriasis
  • Glatiramer acetate (Copaxone): reduces number of relapses in multiple sclerosis in adults
  • Mycophenolate mofetil (CellCept): prevents rejection after renal or heart transplant in adults
  • Sirolimus (Rapamune): prevents rejection after renal transplantation
  • Tacrolimus (Prograf): prevents rejection after liver transplantation
  • Action
    • Inhibit DNA synthesis
  • Contraindications
    • Known allergy, pregnancy, CNS disease, and hepatic disease
  • Drug-to-drug interactions

T and B Cell Suppressor Adverse Effects

  • Increased risk for infection and development of neoplasms
  • Hepatotoxicity
  • Renal toxicity and renal dysfunction
  • Pulmonary edema
  • Possible headache, tremors, and secondary infections such as acne, GI upset, diarrhea, and hypertension

Interleukin Receptor Antagonists

  • Actions
    • Used to treat rheumatoid arthritis
    • Block activity of interleukin-1
  • Pharmacokinetics
    • Given subcutaneously
    • Reach peak in 3 to 7 hours
    • Metabolized in the tissues
    • T½ of 4 to 6 hours
  • Contraindications
    • Known allergy, pregnancy, lactation, and renal impairment
  • Adverse reactions
    • Headache, sinusitis, nausea, and diarrhea
  • Drug-to-drug interaction
    • Etanercept may cause severe and even life- threatening infections

Monoclonal Antibodies

  • Action
    • Antibodies attach to specific receptors
  • Pharmacokinetics
    • Must be injected
  • Contraindications
    • Known allergy and fluid overload
  • Adverse reactions
    • Pulmonary edema, fluid retention, flu-like symptoms
  • Drug-to-drug interaction
    • Severe immune suppression can occur

Use of Immune Modulators Across the Lifespan

Use of Immune Modulators Across the Lifespan
Use of Immune Modulators Across the Lifespan

Prototype Immune Stimulants

Prototype Immune Stimulants
Prototype Immune Stimulants

Prototype Interleukins

Prototype Interleukins
Prototype Interleukins

Prototype T and B Cell Suppressors

Prototype T and B Cell Suppressors
Prototype T and B Cell Suppressors

Prototype Monoclonal

Prototype Monoclonal
Prototype Monoclonal

Nursing Considerations for Immune Stimulators

  • Assessment (history and physical exam)
  • Nursing diagnosis
  • Implementation
  • Evaluation

Nursing Considerations for Immune Suppressants

  • Assessment (history and physical exam)
  • Nursing diagnosis
  • Implementation
  • Evaluation