Essential Clinical Concepts for Healthcare Practice

Posted on Aug 1, 2025 in Airports

Sympathetic vs. Parasympathetic Nervous System Responses

  • Sympathetic Nervous System (SNS) (“Fight or Flight”)

    • Increases heart rate, blood pressure, and respiratory rate
    • Dilates pupils and bronchioles
    • Inhibits digestion and urination
    • Stimulates glucose release from the liver
    • Vasoconstriction increases blood flow to muscles

  • Parasympathetic Nervous System (PNS) (“Rest and Digest”)

    • Decreases heart rate and blood pressure
    • Constricts pupils and bronchioles
    • Stimulates digestion, salivation, and urination
    • Vasodilation increases blood flow to the digestive system

Neurotransmitters and Receptor Types

Adrenergic vs. Cholinergic Systems

  • Adrenergic (SNS) – Uses norepinephrine and epinephrine

    • Receptors:
      • Alpha 1: Vasoconstriction, pupil dilation
      • Alpha 2: Decreases sympathetic outflow, reduces blood pressure
      • Beta 1: Increases heart rate and contractility
      • Beta 2: Bronchodilation, relaxes uterine smooth muscle

  • Cholinergic (PNS) – Uses acetylcholine

    • Receptors:
      • Nicotinic: Found in neuromuscular junctions
      • Muscarinic: Regulate heart rate, secretions, and smooth muscle contraction

Common Reversal Agents

  • Benzodiazepines (e.g., lorazepam, diazepam): Flumazenil
  • Opioids (e.g., morphine, fentanyl): Naloxone (Narcan)
  • Warfarin: Vitamin K, Fresh Frozen Plasma
  • Heparin: Protamine Sulfate
  • Beta-blockers: Glucagon
  • Calcium Channel Blockers: Calcium Gluconate
  • Digoxin Toxicity: Digibind (Digoxin Immune Fab)

Recognizing Serious Adverse Drug Events

  • Serotonin Syndrome (SSRI, SNRI, MAOI overdose)
    • Symptoms: Hyperthermia, tremors, sweating, confusion, seizures, hypertension
  • Neuroleptic Malignant Syndrome (NMS) (Antipsychotics)
    • Symptoms: Fever, muscle rigidity, altered mental status, autonomic instability
  • Extrapyramidal Symptoms (EPS) (First-generation antipsychotics)
    • Symptoms: Dystonia, akathisia, tardive dyskinesia

Important Lab Values & Therapeutic Drug Levels

  • Lithium: 0.6 – 1.5 mEq/L
  • Phenytoin (Dilantin): 10 – 20 mcg/mL
  • Valproic Acid: 50 – 100 mcg/mL
  • Carbamazepine: 4 – 12 mcg/mL

Factors Influencing Metabolic Rate

Metabolic rate is how fast your body burns energy (calories) to keep you alive, similar to a car’s engine running. Some factors make it run faster, while others slow it down.

  • Increased by: Fever, stress, hyperthyroidism
  • Decreased by: Hypothyroidism, fasting, aging

Intravenous (IV) Fluid Types

  • Isotonic: Expands intravascular volume (e.g., 0.9% NaCl, Lactated Ringers, D5W)
  • Hypertonic: Pulls fluid out of cells (e.g., 3% NaCl, D10, D20)
  • Hypotonic: Moves fluid into cells (e.g., 0.45% NaCl)
  • Colloids: Large molecules that stay in the bloodstream (e.g., Albumin, Dextran)

Electrolyte & Acid-Base Imbalances

Normal Electrolyte Levels

  • K+ (Potassium): 3.5 – 5.0 mEq/L
  • Ca2+ (Calcium): 8.5 – 10.5 mg/dL
  • pH (Acid-Base): 7.35 – 7.45

Potassium (K+) Imbalance

  • ⬇ Hypokalemia (Low K+): Arrhythmias, muscle weakness
    • Give KCl (potassium chloride) – NEVER IV BOLUS!
  • ⬆ Hyperkalemia (High K+): Peaked T-waves, cardiac arrest
    • Give Calcium Gluconate, Insulin + D50, Sodium Bicarbonate, Kayexalate

Calcium (Ca2+) Imbalance

  • ⬇ Hypocalcemia: Muscle cramps, Trousseau’s sign
    • Give Calcium Gluconate
  • ⬆ Hypercalcemia: Stones, moans, bones, groans
    • Give fluids, diuretics

Acid-Base Imbalances

  • ⬇ Acidosis (pH < 7.35): Slow breathing, confusion
    • Give Sodium Bicarbonate
  • ⬆ Alkalosis (pH > 7.45): Muscle cramps, twitching
    • Give Normal Saline + Potassium

Endocrine Disorders & Medications

Thyroid Disorders

  • ⬇ Hypothyroidism (Slow Metabolism)
    • Signs & Symptoms (S/S): Fatigue, weight gain, cold intolerance ❄
    • Treatment (Tx): Levothyroxine (Synthroid) – Take in AM, empty stomach
  • ⬆ Hyperthyroidism (Fast Metabolism, Graves’ Disease)
    • Signs & Symptoms (S/S): Weight loss, sweating, tachycardia
    • Treatment (Tx): Methimazole, Propylthiouracil (PTU)

Other Endocrine Conditions

  • Diabetes Insipidus (Excessive Urination)
    • Treatment (Tx): Desmopressin (DDAVP)
  • Adrenal Insufficiency (Low Cortisol, Addison’s Disease)
    • Treatment (Tx): Hydrocortisone, Fludrocortisone

Medication Contraindications & Allergies

  • Penicillin Allergy: Avoid cephalosporins (cross-reactivity)
  • Beta-Blockers (e.g., metoprolol): Avoid in asthma/COPD (bronchospasm risk)
  • MAOIs (e.g., phenelzine): Avoid tyramine foods (cheese, wine = Hypertensive Crisis)
  • Phenytoin: Avoid in pregnancy (birth defects risk)

Metabolism: Anabolism and Catabolism

Metabolism is your body’s way of building up and breaking down energy, encompassing all chemical reactions within your body.

Anabolism (Build Up)

  • Purpose: Growth, repair, energy storage
  • Example: Protein synthesis (building muscle)

Catabolism (Break Down)

  • Purpose: Releases energy (for movement, heat, etc.)
  • Example: Breaking down glucose for ATP

Nutritional Considerations for Specific Diets

  • Ketogenic Diet: Used for epilepsy
  • Low Sodium Diet: Used for hypertension, heart failure
  • Diabetic Diet: Controlled carbohydrate intake

Blood Culture Collection & Antibiotic Administration

  • Always collect cultures BEFORE giving antibiotics
  • Use aseptic technique

Antiseizure Medications

Phenobarbital (Barbiturate)

  • Class: Antiseizure, sedative, GABA receptor agonist
  • Mechanism of Action (MOA): Enhances GABA effects, depressing CNS neuron firing
  • Uses: Treats and prevents seizures (except absence seizures), sedation
  • Adverse Effects: Respiratory depression, sedation, dependency, vitamin deficiencies, coma, death
  • Nursing Implications: Avoid in pregnancy, monitor for CNS depression, taper to discontinue, interacts with CNS depressants

Lorazepam (Benzodiazepine)

  • Class: Sedative-hypnotic, anxiolytic, antiseizure
  • Mechanism of Action (MOA): Enhances GABA receptor activity, inhibiting CNS function
  • Uses: Anxiety, seizures, insomnia, alcohol withdrawal
  • Adverse Effects: Drowsiness, amnesia, respiratory depression, paradoxical reactions
  • Nursing Implications: Flumazenil is the antidote, avoid alcohol/CNS depressants, monitor breathing

Phenytoin (Hydantoin)

  • Class: Antiseizure, sodium-influx suppressant
  • Mechanism of Action (MOA): Desensitizes sodium channels to prevent abnormal CNS discharges
  • Uses: Seizures (except absence), epilepsy
  • Adverse Effects: Gingival hyperplasia, hypotension, rash, ataxia, Stevens-Johnson Syndrome, agranulocytosis
  • Nursing Implications: Therapeutic range: 10-20 mcg/mL, do not give with tube feedings, extravasation risk (purple glove syndrome)