Anesthesia for Patients with Asthma

Asthma is a chronic pulmonary disease characterized by airway inflammation and hyper-responsiveness resulting in episodic wheezing, coughing, breathlessness, chest tightness, and reversible airflow obstruction (1). Worldwide, this condition is estimated to occur in 300 million persons and is implicated in one of every 250 deaths. In the United States, the overall asthma prevalence is 7.7% for adults and 9.5% for children, with a slightly higher prevalence in women (9.2%) than in men (7.0%). A large closed-claim analysis further revealed that although bronchospasm comprised only 2% of the database, around 90% of the claims involved severe brain injury or death. In short, intraoperative bronchospasm—which is most likely to occur at induction—is an uncommon but potentially devastating complication of anesthesia (2). Due to the symptoms of their condition, asthmatic patients undergoing surgery are at risk for perioperative morbidity and mortality, and thus present unique challenges for the anesthesiologist.

A stepwise approach to managing asthma is recommended to gain and maintain preoperative disease control in asthmatics scheduled to undergo general anesthesia. As the disease increases in severity, the number and types of medications used to treat the patient also increase (1). For patients with mild symptoms, long-acting beta-2 agonists are a good form of preoperative therapy, and can often provide short-term relief from bronchospasm. However, long-acting agents do not suppress inflammation and should not be used without anti-inflammatory treatment for the control of asthma (2). On the other hand, inhaled corticosteroids are potent anti-inflammatory agents that constitute the mainstay of therapy for patients with persistent asthma. Corticosteroids have been shown to reduce airway reactivity and block reactions to provocative allergens (1). Asthmatic patients who are treated with corticosteroids preoperatively have been shown to have a low incidence of complications during surgery (1).

Preoperative assessment and intervention is key to the successful management of a patient with asthma. When asthma is well controlled, it probably confers no additional risk for perioperative complications; when it is poorly controlled, it almost always does (2). Patients can be asymptomatic at the time of evaluation. However, key clues to severe disease include a history of frequent exacerbations, hospital visits, and, most importantly, prior tracheal intubation and mechanical ventilation to deal with a severe attack. The patient should be interrogated regarding their most common triggering agents—they will usually be acutely aware of them. Type, dose, frequency, and degree of benefit of therapy provide important clues to the severity and control of the disease. Lastly, the preoperative physical examination should focus on detecting signs of acute bronchospasm or active lung infection (which should defer elective surgery), chronic lung disease, and right heart failure (2).

The main goal of anesthetizing a patient with asthma is to avoid bronchospasm and reduce the response to tracheal intubation (1). It is extremely important that the patient be at a deep level of anesthesia prior to instrumenting the airway, as tracheal intubation during light levels of anesthesia can precipitate bronchospasm. As for intravenous anesthetics, propofol is the induction agent of choice in the hemodynamically stable patient due to its ability to attenuate the bronchospastic response to intubation both in asthmatics and non-asthmatics (3). Care should be taken in patients with depressed cardiac function, as propofol decreases cardiac contractility and chronicity (1). Volatile anesthetics are excellent choices for general anesthesia, as they depress airway reflexes and produce direct bronchial smooth muscle relaxation (2). Sevoflurane has emerged as the volatile agent of choice, as studies indicate it has the most pronounced bronchodilatory effect of all volatile anesthetics. Desflurane increases airway resistance and should be avoided in asthmatics, specifically at lighter levels of general anesthesia (3).

The postoperative care of the asthmatic patient is often dictated by the intraoperative course. If the surgery was uneventful, and pain, nausea, and respiratory status are well-controlled, asthmatics may safely be discharged either to home or to an appropriate inpatient unit

without further intervention. However, in the setting of significant intraoperative complications such as severe bronchospasm, special care must be taken to ensure patient safety during the postoperative period. Postoperative ventilation should be considered, allowing time

for further medical management, recovery of airway function, and metabolism of neuromuscular blockers without the need of reversal agents (1).

References

1. Applegate R, Lauer R, Lenart J, Gatling J, Vadi M. The perioperative management of asthma. J Allergy Ther. 2013;S11:007.
2. B. D. Woods, R. N. Sladen, Perioperative considerations for the patient with asthma and bronchospasm, BJA: British Journal of Anaesthesia, Volume 103, Issue suppl_1, December 2009, Pages i57–i65, https://doi.org/10.1093/bja/aep271
3.  Burburan SM, Xisto DG, Rocco PR. Anaesthetic management in asthma. Minerva Anestesiol. 2007;73(6):357–365.