Asthma and Obstructive Sleep Apnea Flashcards
Definition and Epidemiology Pathophysiology of Asthma Risk factors Clinical features, evaluation and diagnostics Treatment Patient Education and Home monitoring Complications
Definition of Asthma
Characterized by airway inflammation, airway hyperreactivity, and reversible airway obstruction
Classification of Asthma (Types)
Intrinsic: no documented history of allergies; attack triggered by URI, stress, GERD Extrinsic: Allergic asthma. Allergen exposure and hx of atopy Exercise-Induced: Symptoms begin 5-10 minutes into exercise and resolve with rest Occupational: Inquire into occupational exposure
Pathophysiology of Asthma
Airway Hyperresponsiveness –Exaggerated bronchoconstriction response to stimuli, inflammation, dysfunctional neuroregulation, and remodeling
Bronchoconstriction– bronchial smooth muscle contraction in response to stimuli. IgE dependent release of mediators from Mast Cells (histamine, tryptase, leukotrienes, prostaglandins). Less well defined in cold air, ASA/NSAID, exercise and stress induced asthma.
Airway Edema –Mast cell mediation inflammation, mucus hypersecretion and remodeling
Airway remodeling-- Subepithelial fibrosis, smooth muscle hypertrophy and hyperplasia, angiogenesis
More generally, think:
**Airway hyperresponsiveness is the tendency of airway smooth muscle to constrict in response to inhaled irritant. The irrant causes mast cell degranulation by binding to IgE, leading to bronchoconstriction, edema, and mucus secretion. **
Historical clinical features of Asthma
Typically diagnosed before age 7
Triad: wheezing, episodic dyspnea, chronic cough
Sxs are worse at night
Chracteristic triggers: allergens, cold air, exercise
Personal or FHx of atopy
Features that make the probability of asthma less likely:
Lack of improvement with anti-asthmatic meds (inhalers and oral steroids)
Onset of sxs after 50
Associated sxs such as CP, lightheadedness, syncope, and palpations
Hx of smoking >20 pack years (think COPD)
Physical Exam Findings of Asthma
Characteristic feature: Diffuse expiratory wheezing on auscultation
**Vital signs: **
- Tachypnea, tachycardia, use of accessory muscles
- Asaccessory muscles begin to fatigue: bradypnea
- Hypoxia: mental status changes. fever
Upper airway: signs of allergy, nasal mucosa swelling, rhinorrhea, polyps
**Lower airway: **
- Hyper-expansion of the thorax
- Accessory muscle use
- Wheezing
- Prolonged expiration or force expiratory wheeze (not a reliable indicator of airflow limitation)
Skin: atopy
Differential Diagnosis of Wheezing
PE
Cardiac Failure
Foreign Body
Central Airway Tumors
Aspiration
Laryngeal Edema
Anxiety Disorders
Evaluation of Asthma
Pulmonary Function Testing:
- Spirometry: FEV1 and FEV1/FVC will be decreased (follows obstructive pattern)
- PEFR: monitoring tool to help with early intervention
- Bronchodilator response: should see improvement when bronchodilator is administered
- Lung Volumes/DLCO
- Bronchoprovocation Testing
Peak Expiratory Flow Rate in Monitoring Asthma
Good tool for monitoring pts with an established diagnosis. PEFR diary.
Peak flow zones:
- Green Zone: (80-100%): Asymptomatic. Where you should be everyday.
- Yellow Zone (50-79%): Mild to moderate sxs. If don’t improve with rescue medications, call your doctor.
- Red Zone (<50%) Take rescue medications. Medical Emergency.
Limitations of PEFR:
- Peak flow meters can’t be calibrated
- Technique determines the validity of the measurements
- Not useful in distinguishing between upper or lower airway obstruction or restriction lung dz
*
Danger signs in asthma
Use of acessory muscles
Fragmented speech
Unable to lay flat
Profound diaphoresis
Agitation
Unable to protect airway (mechanical ventilation may be needed)
Cyanosis
Decreased LOC
Status Asthmaticus
Severe bronchospasm:
- Hypoxemia and expiratory flow continue to decrease
- Effective ventilation decrease
- Acidosis develops
- Arterial PaCO2 begins to rise
Life threatening signs
- Silent chest (no audible air movement)
- PaCO2 >70mmHg
Patient Education and Monitoring of Asthma
Goals:
- Improve quality of life: improve sxs; address fears, misconceptions; encourage family support
- Improve medication compliance
- Fewer UC/ER/Hospital visits
Definition of Obstructive Sleep Apnea
Repetitive upper airway obstruction during sleep with cycles of sleep, snoring, obstruction, arousal and sleep
This causing excessive daytime sleepiness, poor neurocognitive performance and increased risk for medical disorders
Definition of Central Sleep Apnea
Periodic cessation of airflow (10 or more seconds) during sleep due to the lack of stimulation to respiratory muscles, sometimes not associated with an arousal from sleep
Seen with neurologic abnormalities: CVA, postpolio syndrome, endocrine dysfunction, idiopathic
Risk factors
Obesity
Current Smokers
Nasal Congestion
Short neck
Tonsillar Hypertrophy
Facial Abnormalities (Curling of lower lip; small, receding jaw)
