Case study: Asthma (3)
A 13-month-old male is scheduled for myringotomy and tube insertions. He has a history of wheezing with colds, for which he takes nebulized albuterol as needed. His last episode of wheezing with a cold was 3 weeks ago.
Is there anything else you would like to know before proceeding with general anesthesia?
I’d like to know more about his respiratory history. Specifically, I’m interested to know whether he ever required an emergency room visit or hospitalization for his asthma. This will give me a better idea of the severity of his illness. I want to know about his recent health, with regard to viral illnesses, and I will ask the parents if he is exposed to cigarette smoke at home. Children exposed to second-hand smoke tend to exhibit more airway complications during general anesthesia.
On physical exam, I’ll pay careful attention to the respiratory system. I’ll try to detect the presence of wheezing on auscultation of the lungs, and I will examine his chest to detect use of accessory muscles of respiration. Respiratory rate and pulse oximetry values should be normal.
How will you induce and maintain general anesthesia in this child? Is it any different from a child without asthma?
This child will receive premedication with oral midazolam 0.5mg/kg, and oral acetaminophen 15mg/kg. He will then undergo induction and maintenance of general anesthesia with sevoflurane by facemask throughout the entire procedure, which should last no longer than 10 minutes. I will administer 1-2 mcg/kg of intranasal fentanyl to provide postoperative analgesia. As long as this child does not demonstrate wheezing, I will not do anything differently than I would for a child without asthma. For example, prophylactic inhaled albuterol will not be administered, and no IV line is necessary.
During the procedure you detect wheezing through the precordial stethoscope. What will you do?
Wheezing is a sign of bronchospasm but can also be caused by other entities. Initially, I will rule out light anesthesia and upper airway obstruction by deepening the general anesthetic while I reposition the head and neck, and suction out the oropharynx to clear any secretions. Simultaneously, I will examine the chest, feel the ventilation bag and observe the capnography tracing, all of which can give me clues about efficacy of air entry and expiratory time. I’m trying to differentiate upper from lower airway obstruction. These maneuvers, in combination with deepening the anesthetic using positive-pressure ventilation, will extinguish wheezing in almost all cases without requiring bronchodilator therapy.
How will your treatment differ if the patient is tachypneic and is wheezing in the post-anesthesia care unit (PACU)?
Wheezing in the PACU requires a different treatment strategy from the intraoperative setting. Oxygen supplementation will be administered if the oxyhemoglobin saturation is below 96% on room air. Treatment will consist of nebulized albuterol, 2.5 mg diluted in 3–4 mL of normal saline. In the majority of cases, one treatment is all that is needed for the wheezing to abate, and the child can then be observed and discharged to home if otherwise well. Reasons for hospital admission will include continuing bronchospasm that is not responding to one or two bronchodilator treatments, and a persistent oxygen requirement. Intravenous access will be required for administration of methylprednisolone 2.5 mg/kg. If the child appears to be in pain, I will administer oral oxycodone 0.1 mg/kg.