What preoperative evaluation and preparation
would you order for this patient? Would you cancel the case if the patient said
that she was just recovering from a “bad cold” and had a few scattered wheezes
on auscultation? Would you continue the aminophylline during the perioperative
period?
History and physical examination are the first
step. Important information to elicit is the frequency and severity of attacks,
the response to treatment, the need for emer-gency room visits, hospital
admissions and mechanical ventilation, and the use of systemic steroids (dose,
dura-tion, last use). If the patient uses a peak expiratory flow (PEF) device,
the best PEF and the current value should be obtained. There is probably no
benefit in obtaining pre-operative PFTs for a patient with asthma. Although the
importance of the presence of wheezing on physical exam-ination is often
discussed, it should be noted that severe bronchospasm often manifests as
almost absent breath sounds with little to no wheezing.
Patients with mild asthma do not need any
special test-ing or preparation. Oral medications such as cromolyn, leukotriene
inhibitors, and steroids should be continued until the day of surgery. The
patient should use their MDI β2-agonist before entering the operating room because this has been shown to decrease the incidence of intra-operative
bronchospasm. As appropriate, infection should be eradicated with antibiotics;
chest physiotherapy should be used to improve bronchial drainage; and cessation
of smoking should be maintained for at least 2 months to restore ciliary
function and decrease mucus production. Cessation of smoking for 12–48 hours
preoperatively decreases carboxyhemoglobin concentrations but has been shown to
increase mucus production and possibly lead to an increased incidence of
postoperative pulmonary complications.
The 1991 National Institutes of Health (NIH)
expert panel recommended that asthmatics with an FEV1 <80% of
predicted receive a preoperative course of oral steroids. This has been shown
to decrease perioperative pulmonary complications. Wound healing and infection
is not affected by a short course of steroids. Treatment should be initiated
24–48 hours before surgery and can consist of 40–60 mg of prednisone per os
once a day or 100 mg of hydrocortisone intravenously (IV) 8-hourly. This should
be continued for 1 or 2 days after surgery and can usually be discontinued
without tapering.
A history of recent airway viral infection
increases airway reactivity in normal patients, and is one of the main triggers
for exacerbations. In the adult patient with a clear chest auscultation, it is
probably safe to proceed. Whether an elective case should be delayed in a
sympto-matic patient is controversial and no clear cut-off point can be given
beyond which the risks justify the inconven-ience. Response to treatment with
inhaled β2-agonists
and steroids might help in determining the risk. A small child, on the other
hand, would have more severe bronchospasm with the same trigger, because the
airway diameter is smaller. Therefore, an elective case should be delayed for a
few weeks. A recent study confirmed the increased inci-dence of adverse
respiratory events in children with upper respiratory infections, but no
long-term sequelae were noted.
If there are no signs of toxicity, such as
tachycardia, tremulousness, nausea or vomiting, aminophylline should be
continued during the perioperative period, with drug levels checked as
indicated.
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