Managing Intraoperative Bronchospasm
Bronchospasm, or the severe constriction of bronchial smooth muscle, is a potentially dangerous complication that every anesthesia provider should be prepared to manage in the operating room. With an overall incidence of 0.2%, bronchospasm is relatively rare, but common enough that nearly every provider in the operating room will encounter bronchospasm several times in their careers, especially providers who care for children. Risk factors for bronchospasm include any type of reactive airway disease, most commonly asthma or COPD, as well as history of smoking or recent upper respiratory infection. Bronchospasm can be an isolated sign or part of an anaphylaxis reaction, and is thought to be caused by simultaneous bronchial constriction, mucosal edema and mucous plugging. Luckily, bronchospasm is a reversible smooth muscle spasm. However, anesthesia providers must be especially equipped to handle bronchospasm because it is often caused by airway manipulation, which can include instrumentation (eg. intubation), or other noxious stimuli such as gas inhalation, cold air, etc.
In a clinical scenario, when a patient is being mechanically ventilated, bronchospasm presents with the following signs: sudden increase in peak airway pressures (with stable plateau pressures), wheezing (or lack of airflow) on auscultation, and difficulty or inability to ventilate the patient. The provider may also notice an upslope in the capnography graph, indicating obstruction to exhalation, as well as decreased tidal volumes. The first step in treatment of bronchospasm is diagnosis. Other issues that can potentially present similarly must be ruled out, and these include ETT obstruction (kink, mucous in the tube, etc.), pulmonary edema, tension pneumothorax, foreign body, aspiration, and pulmonary embolism. Once the diagnosis of bronchospasm is being considered, the provider should switch to 100% oxygen, and take the patient off the ventilator and begin hand ventilating the patient. This will allow the provider to determine if the lungs are having difficulty ventilating. At this point, if anaphylaxis is being considered, check for rash, monitor blood pressure, and stop any possible offending agents. Rule out an ETT obstruction or other causes of high pulmonary pressures. If bronchospasm has risen to the top of the differential, the provider should deepen anesthesia and give albuterol (or a similar bronchodilator) aggressively via the ETT circuit. If the patient’s respiratory status does not improve, give epinephrine IV (10-100 mcg), titrating to patient response. IV ketamine, as well as Ipratropium and IV steroids, can all also be considered as well, though long acting beta agonists and steroids are more long term solutions that will help over the following several hours.
Like many potential complications in the operating room, bronchospasm is more easily prevented than treated. Providers should take prophylactic measures in patients with reactive airway disease to help prevent bronchospasm before it starts. Asthmatics and patients with COPD should receive bronchodilators prior to surgery. If severe, IV or oral steroids should be considered before surgery as well (these will take hours to work, so should be given well in advance of the operating room). In addition, if sedation (without an airway device) or a supraglottic airway (rather than an endotracheal tube) can be safely used, avoiding direct airway manipulation can decrease the chance of bronchospasm in a patient with a very reactive airway.
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Morgan GE, Jr., Mikhail MS, Murray MJ, “Chapter 23. Anesthesia for Patients with Respiratory Disease” (Chapter). Morgan GE, Jr., Mikhail MS, Murray MJ: Clinical Anesthesiology, 4e