High bronchospasm risk – The big concern in asthmatics is bronchospasm. This has been reported to happen during 0.2% – 4.2% of procedures on asthmatics using general anesthesia. Upper abdominal surgery and oncological procedures are the highest risk.

Signs/symptoms of bronchospasm – upsloping ETCO2 waveform, wheezing, high PIP, desaturation

Avoiding bronchospasm – Avoid light anesthesia. This is the number one cause of bronchospasm in general – asthma patients will be especially at risk of bronchospasm if light. Avoid airway instrumentation (where possible). Regional anesthesia is an attractive option to avoid instrumenting the airway and inducing a bronchospasm. LMA use, if not contraindicated, will also reduce the chances of bronchospasm when compared to using an ETT tube. Deep extubation should be considered if not contraindicated. Preoperative steroids have shown little benefit in preventing bronchospasm unless started 2 or 3 days in advance of surgery.

Other ways to avoid bronchospasm – to avoid bronchospasm throughout the perioperative period, you’ll want to treat pain and suppress CNS stimulation using opioids that do not trigger histamine-release. Remifentanil is recommended, but fentanyl is the more practical option that is proven to be safe with asthmatics.

Preoperative assessment – auscultate for expiratory wheezes, crepitus, and use of accessory muscles. No wheezing should be heard prior to surgery. An ABG should be obtained if there is any question whatsoever about the adequacy of oxygenation or ventilation. Eosinophil counts can help gauge the level of airway inflammation. Check pulmonary function tests if available. PEFR should be > 80% OR at the patients personal best prior to surgery. Radiographs most often appear normal. Hilar vascular congestion and hyperinflation may be seen in patients with severe asthma

Prescribed anti-inflammatory or bronchodilator therapy – should continue up to induction of anesthesia.

Treatment – Options for treatment of asthma during the perioperative period include using antibiotics, chest physiotherapy, and bronchodilators.

Drug considerations – Lidocaine is good for suppressing cough reflexes (1.5 mg/kg) that can lead to bronchospasm. Use of non-depolarizing paralytics is best. Succinylcholine triggers histamine release. Neuromuscular blockade will have no effect on preventing or treating a bronchospasm. Ketamine is an excellent IV anesthetic for these patients as it will both sedate and bronchodilate. Use opioids that have a fast onset/offset (e.g. remifentanil). These are preferred to avoid prolonged respiratory depression. Avoid any opioids that would trigger histamine release (e.g. morphine). NSAIDs have been shown to induce asthma/bronchoconstriction in asthmatics

Choice of inhaled anesthetic – use the least pungent inhaled gas (sevoflurane < isoflurane < desflurane)

Upper respiratory infection – There is an 11-fold increase in respiratory risk in patients with asthma when the patient also has an active upper respiratory infection. Recommendations are to wait for 2-3 weeks AFTER RECOVERY from the URI before elective surgery.

Major surgery – consider checking pulmonary function tests (with a focus on FEV1) prior to and after bronchodilator therapy. Perioperative respiratory complications risks are high in patients demonstrating:
Less than 70% predicted FEV1
Less than 70% predicted FVC
FEV1:FVC ratio less than 65%

Asthma is considered an obstructive respiratory disease

Worldwide, this condition affects more than 300 million people.

Causes are believed to be both genetic and environmental. Genetic factors would include a family history of asthma and exposure to viruses such as rhinovirus and RSV. Environmental factors include limited exposure to infectious environments. These would include public daycares, farms, etc.

The array of symptoms include wheezing, chest tightness, shortness of breath, bronchial hyperreactivity, bronchoconstriction, and chronic lower airway inflammation. Chronic inflammation leads to thickening of the basement membrane as well as edema within the airway wall. This all leads to disruption of normal gas exchange within the lower airways.

Asthma is characterized by exacerbations and remissions. Remissions are typically symptom-free. In very few cases, symptoms will persist for days after an attack.

Treatment resistant bronchospasm is known as status asthmaticus, a medical emergency.

Treatment with a bronchodilator which is quickly followed by an increase in pulmonary air flow is a diagnostic indicator of asthma.

Further diagnostics helpful for assessing the severity of airway obstruction would include pulmonary function tests. Asthmatics MAY demonstrate a reduced FEV1, FEF, PEFR, and midexpiratory phase (FEF 25%–75%). Most patients that present to the hospital for an asthma attack will demonstrate an FEV1 of less than 35% of normal.

Differential diagnoses include COPD, foreign body aspiration, viral tracheobronchitis, sarcoidosis, rheumatoid arthritis with bronchiolitis, epiglottitis, croup, mediastinal compression, thoracic aneurysm, vocal cord dysfunction, tracheal stenosis, congestive heart failure, pulmonary embolism, and chronic bronchitis.