M10

• Ventilation


  The movement of air from the atmosphere through the upper and lower airways to the alveoli
• Respiration


  The process whereby gas exchange occurs at the alveolar-capillary membrane
• Phases of respiration

  • Ventilation
  • Perfusion
  • Diffusion
• Ventilation


  The phase in which oxygen passes through the airways
• Perfusion


  Involves blood flow at the alveolar-capillary bed
• Diffusion


  Takes place when oxygen passes into the capillary bed to be circulated, and carbon dioxide leaves the capillary bed and diffuses into the alveoli for ventilatory excretion
• Acute rhinitis


  The common cold is caused by the rhinovirus and affects primarily the nasopharyngeal tract
• Acute rhinitis


  Acute inflammation of the mucous membranes of the nose
• Acute rhinitis is not the same as allergic rhinitis, often called hay fever, which is caused by pollen or a foreign substance (e.g., animal dander)
• Nasal secretions increase in both acute rhinitis and allergic rhinitis
• A cold is most contagious 1 to 4 days before the onset of symptoms (the incubation period) and during the first 3 days of the cold
• Antihistamines (H1 blockers or H1-receptor antagonists)


  Commonly used as cold remedies, also used to treat allergic rhinitis
• Antihistamines


  Do not prevent histamine release, but they reduce the symptoms of an allergic reaction if the concentration of the antihistamine exceeds the concentration of histamine at the receptor site
• Antihistamines are more effective if they are taken before histamine is released or when symptoms first appear
• Diphenhydramine is also used as an antitussive to alleviate cough
• First-generation antihistamines

  • Diphenhydramine
  • Chlorpheniramine
  • Clemastine fumarate
• Second-generation antihistamines

  • Azelastine (nasal spray)
  • Cetirizine
  • Loratadine
• Mechanism of action of antihistamines

  Antihistamines, or H1-receptor antagonists, are chemical agents that compete with the allergy-liberated histamine for H1-receptor sites in the patient's arterioles, capillaries, and secretory glands in the mucous membranes
• Therapeutic outcome of antihistamines

  Reduced symptoms of allergic rhinitis (e.g., rhinorrhea, lacrimation, itching, conjunctivitis)
• Antihistamines should be used with caution in patients who have a productive cough. If the cough continues but becomes nonproductive, consider additional hydration and discontinue the antihistamine
• Diphenhydramine blocks the effects of histamine by competing for and occupying H1 receptor sites. It has anticholinergic effects and should not be used by patients with narrow-angle glaucoma
• Side effects of first-generation antihistamines

  • Drowsiness, dizziness, fatigue, and disturbed coordination
  • Skin rashes and anticholinergic symptoms such as: dry mouth, urine retention, blurred vision, and wheezing may occur
• Side effects of second-generation antihistamines

  Have little to no sedating effect, fewer anticholinergic symptoms
• The most common adverse effect of many antihistaminic agents is sedation
• Nursing implications for antihistamines

  • Review the patient's history for evidence of glaucoma, prostatic hyperplasia, or asthma
  • Inquire about urinary pattern, particularly in male patients over the age of 55 who may be developing prostatic hyperplasia
  • Assess cardiac and respiratory status
  • Assess for signs and symptoms of urinary dysfunction, including retention, dysuria, and altered frequency
  • Note complete blood count (CBC) during therapy
  • Assess the patient's work environment and consider whether drowsiness will affect safety and work performance
  • Warn patients to avoid driving a motor vehicle and performing other dangerous activities if drowsiness occurs or until stabilized on the drug
  • Advise patients to avoid alcohol and other central nervous system depressants
  • Encourage patients to take drugs as prescribed. Notify a health care provider if confusion or hypotension occurs
  • Teach patients on prophylaxis for motion sickness to take diphenhydramine at least 30 minutes before the offending event and also before meals and at bedtime during the event
  • Inform breastfeeding mothers that small amounts of drugs pass into breast milk. Because children are more susceptible to the side effects of antihistamines (e.g., unusual excitement or irritability), breastfeeding is not recommended while using these drugs
• Antitussives


  Act on the cough-control center in the medulla to suppress the cough reflex
• Types of antitussives

  • Opioid antitussives
  • Nonopioid antitussives
  • Expectorants
• Opioid antitussives

  Codeine, Guaifenesin, Codein
• Nonopioid antitussives

  Benzonatate, Dextromethorphan
• Expectorants

  Guaifenesin, Dextromethorphan
• Mechanism of action of dextromethorphan


  Reduces the viscosity of tenacious secretions, acts as a nonopioid antitussive by changing a nonproductive cough to a less frequent, productive cough, acts directly on the medullary cough center of the brain to depress the cough reflex, but does not suppress respiration
• Therapeutic outcome of antitussives


  Reduced frequency of nonproductive cough
• Antitussives are not given to patients who have undergone thoracic and abdominal surgeries because they need to cough to maintain airway patency
• Precautions are instituted when giving antitussives to patients with asthma, emphysema, or COPD because an accumulation of secretions may occur
• Side effects of antitussives


  • Respiratory: dryness of mucosal membranes, increased viscosity of secretions
  • CNS: drowsiness, dizziness, and sedation
  • GIT: nausea, constipation, and dry mouth, GIT upset
• Adverse effects of antitussives include nephrolithiasis, psychosis, respiratory depression, and serotonin syndrome
• Nursing implications for antitussives


  • Emphasize that the drug should be taken only on a specified time frame as ordered
  • Provide other measures to relieve cough like provide humidified oxygen, cool temperatures, fluids, and use of lozenges
  • Caution that alcohol, narcotics, sedatives-hypnotics can cause CNS depression when used with antitussives
• Outcome expected from antitussive therapy


  Reduced frequency of nonproductive cough
• Side effects of antitussives

  • Respiratory: dryness of mucosal membranes, increased viscosity of secretions
  • CNS: drowsiness, dizziness, and sedation
  • GIT: nausea, constipation, and dry mouth, GIT upset
• Adverse effects of antitussives

  • Nephrolithiasis, psychosis
  • Respiratory depression, serotonin syndrome