Respiratory diseases and anesthesia Flashcards
What factors increase anesthesia risk with a respiratory tract infection?
- underlying resp disease
- smokers/second hand
- manipulation of airway (intubation vs lma)
- within 6 weeks of active infection
Intraoperative management of acute repirtory infection
- hydrate
- reduce secretions
- limit manulation
*prophylactic bronchodilators? Not established
Asthma is characterized by
REVERSIBLE expiratory airway obstruction
chronic airway inflammation increases resistance
bronchial hyperractiviity = bronchospasm
asthma anesthesia considerations
- deep anesthesia
- steroids before extubation
1 astham pathogenesis/cause
Atopy (allergies)
asthma diagnosis flow-volume loop
Flow volume loops show characteristic downward scooping of expiratory limb
Asthma diagnosis FEV1 (forced expiratory volume in 1 second) and MMEF (mid-expiratory flow rate)
direct measure of airflow obstruction
What helps determine asthma vs airway obstruction
where loop is flat helps determine where the obstruction is (inhaled or exhaled portion)
FRC in asthma
moderate - severe increased
TLC in asthma
remains unchanged
Diffusing capacity for CO and asthma
does not change
PaO2 and astham
mild asthma PaO2 is normal
Drug classes for asthma
- anti-inflammatory drugs (corticosteroids)
- Bronchodilators (beta agonsits and antocholinergics)
- Methylxanthines
In asthma, what indicates intubation?
PaCO2 > 50 despite aggressive anti-inflammatory and bronchodilator therapy - respiratory fatigue
Prior to surgery in asthmatic, what does optimization look like
- peak expiratory flow > 80% predicted
- absence of wehezes
Asthma PFTs prior to surgery: what predicts risk for perioperative complications?
- FEVV1 < 70% predicted
- FEV1/FVC ration less than 65%
Asthma induction
Propofol > etomidate
Ketamine = bronchodilation (but increases secretions, consider glycopyrolate)
Ventilator strategies in asthma
- LMA > ETT
- decrease inspiratory flow rate, longer exhalation
- humidification
- avoid histamine
- deep extubation/ lidocaine
Bronchospasm presentation
rapid increase in peak airway pressure and inability to ventilate (but consider other possibilities as cause)
bronchospasm treatment
- deepen anesthetic
- bronchodilator (albuterol)
- corticosteroid administration (hours)
FEV1 range
forced expiratory volume in one second
based on age and gender
normal is within 80% of predicted values
What is useful in distinguishing between restrictive and obstructive disesase
FEV1/FVC
should be greater than 0.7
less than 0.7 = obstruction