Affects: up to 22 million in the US
Reversible airflow obstruction unlike COPD - bronchoconstriction, airway inflammation, hyperirritability of tracheal tree
Wheezing, productive/nonproductive cough, dyspnea, chest discomfort that may lead to air hunger, tachypnea, prolonged expiratory phase, and fatigue. Eosinophilia (can be elevated).
Allergens, pharmacologic agents (aspirin, beta-antagonists, some non-steroidal anti-inflammatory drugs, sulfiting agents, infections), exercise (mainly after), emotional stress.
Diagnose severity with flow volume measurements. The normal FEV1/FVC ratio is >80% in normal people, and FEV3/FVC is >95% in normal people. Asthma patients have higher lung volumes as they cannot "get rid" of the air, which is why FRC (Functional Residual Volume) is increased
Hyperreactive airway increases the risk of bronchospasm
Cessation of cigarette smoking 8 weeks before surgery is optimal
Optimal airway status - no acute infection
Sedate to avoid anxiety
Anticholinergic drugs increase the viscosity of secretions, making them more challenging to remove. Propofol is used due to its relative broncho-dilating effect compared to Thiopental
Consider pretreatment with systemic corticosteroids
H2 blockers (Zantac/Tagamet) should be avoided as they have been associated with bronchospasm
Consider regional anesthesia if not contraindicated (avoid levels above T6)
Use laparoscopic procedures if possible
Mask and LMA preferred over ETT
Give Lidocaine to attenuate the effect of DL. Another option is to mask with a volatile agent (Sevoflurane, as it is less irritating to the airway) and deepen the anesthetic level prior to intubation.
Avoid nondepolarizing muscle blockers known for Histamine release (Atracurium). Histamine release has been attributed to Succinylcholine, but there is no evidence of increased airway resistance in asthmatic patients
Morphine and Meperidene can cause histamine release as well
Consider Fentanyl (2 mcg/kg low dose) for attenuation of DL/surgical incision
Ventilation: A slow inspiratory flow rate provides optimal ventilation distribution relative to perfusion. Sufficient time for exhalation to prevent air trapping (prolong inspiratory time?)
Avoid PEEP - may impair adequate exhalation in narrow airways
Liberal administration of fluids for hydration and less viscous airway secretions
Before extubation, consider giving IV Lidocaine or inhaled bronchodilator (beta-2-agonist) to prevent any bronchospasm
Deep versus awake extubation
Deepen the anesthetic level
100 % O2
Beta-2-agonist
Epinephrine IV or SQ
IV corticoids 2-4 mg/kg
Consider aminophylline drip for long-term post-op mechanical ventilation
If bronchospasm does not resolve, check for kinking of ETT, secretions, overinflated balloon, bronchial intubation, active expiratory efforts, pulmonary edema or embolism, and pneumothorax.