One of the most common dilemmas for the pediatric anesthesiologist is deciding whether to anesthetize a child who has just recovered from or currently has an upper-respiratory-tract infection (URI). This situation is challenging even for experienced providers who have lots of judgment and experience in this area—junior anesthesiologists should not be at all hesitant about seeking help and advice.

The first problem is to determine if the child has an URI at all. When is a runny nose secondary to an URI, and when is it due to allergic rhinitis? Remember that the symptoms that the parents are most likely to tell you about (“he’s had a runny nose” or “a little bit of a cold”) can be very similar to those of other illnesses or allergies. The most reliable way to tell the difference between an URI and allergic rhinitis or other benign entities is to get further history from the parents. If they relate that the child developed symptoms while in daycare or that he has sick siblings, it is probably an URI. Also, you should suspect that the child has an URI if the parents tell you that their child’s symptoms are new and not a routine occurrence. There are, however, some children who “keep a cold.” In one study, the probability of having an URI in a child younger than 3 years, in daycare, with parents who smoke in crowded house was 0.61 in any given 2-week period! Signs that are associated with an URI include purulent rhinorrhea, fever, sore throat, productive cough, and other lower-tract signs, such as wheezing or rhonchi. Allergic rhinitis is not associated with fever or productive cough, rhinorrhea is usually clear, and it is often associated with a history of atopy.

The second problem is determining whether the URI will affect the child’s anesthetic course. Early studies demonstrated that what is thought to be purely an URI might also involve the lower airways and be associated with decreased pulmonary function, and increased reactivity for up to 6 weeks after the infection. In viral airway infections, much of the bronchial hyperreactivity is vagally mediated. Some viruses are thought to produce a viral neuraminidase that decreases the function of M₂ muscarinic receptors. As a result, there is increased release of acetylcholine in virus-infected airways. There may also be a decrease in the activity of airway neutral endopeptidase, an enzyme responsible for inactivating tachykinins. These effects render the
lower airways more susceptible to smooth-muscle contraction, thus increasing airway reactivity.

The typical URI also is associated with more airway secretions. The combination of increased secretions with increased reactivity leads to the adverse events often described in clinical studies of anesthetized children with URIs: coughing, breath-holding, laryngospasm, bronchospasm, and episodes of desaturation.

The next question is which procedures should be cancelled to avoid serious complications in the child with a URI? Children who present for an elective procedure with moderate-to-severe signs and symptoms of fever, myalgias, lassitude, wheezing, or rhonchi are easily discerned as being at high risk, and their procedures should be delayed. However, those who present with mild or recent symptoms are also at risk for adverse events. One study evaluated more than 1,000 children scheduled for elective surgery who were either well, had a recent URI (within 4 weeks), or had an active URI. The incidence of adverse respiratory events was greater in the children with recent or active URIs than in the children who were well. Independent risk factors for respiratory complications in children with an URI were copious secretions, presence of an endotracheal tube (ETT) in children less than 5 years of age, history of premature birth, nasal congestion, paternal smoking, history of reactive airway disease, and airway surgery. The more serious complications of laryngospasm and bronchospasm were not different among the groups. A second study compared the cases of 1,280 children with preoperative URIs with those of 20,876 children without preoperative URIs and demonstrated that there was an 11-fold increase in the risk of a respiratory complication if the child with an URI required intubation. The first study also confirmed that an ETT in the presence of an URI contributed to more adverse respiratory events, although these events were primarily breathholding.