The Science Journal of the American Association for Respiratory Care
Background: Cardiac asthma is a term used to describe asthma-like symptoms in the presence of severe pulmonary congestion and acute heart failure. The primary characteristics of cardiac asthma are a combination of high pitched inspiratory and/or expiratory wheezing, marked dyspnea, and pronounce inspiratory crackles. Cardiac asthma can also be identified by its response to diuretic therapy and by being refractory to standard treatment of bronchial asthma. Stridor is a harsh, high-pitched wheeze that is characterized as inspiratory, expiratory, or biphasic. It has a frequency of 400 to 800 hertz (normal conversation is around 20 hertz).
Methods: It was postulated that stridor was due to one or more of the following: A. traumatic intubation, B. excessive endotracheal tube cuff pressures (>25cm H2O), C. prolonged length of intubation [(LOI) >24 hours post-op)]. Initial treatment of upper airway wheezing (stridor) consisted of albuterol sulfate 2.5mg/3cc NSS via high flow nebulizer (HFN), racemic epinephrine 0.1 to 0.5cc of a 2.25% solution/3cc NSS via HFN, ipratropium bromide 0.5 mg/3cc NSS via HFN, and patient placement in the Fowlers position. Furosemide was added to the treatment plan secondary to the frequency of crackles, which unremarkably reduced the work of breathing.
Results: During a four month period, 454 cardiac surgery procedures were completed of which 28 patients developed 33 cases (6%) of upper airway wheezing (stridor) approximately 72 hours post-op. Of the 33 cases, 19 (57%) cases required aggressive treatment and remained on the nursing unit [furosemide 20 to 80 mg IVP was given within 5 minutes of onset of symptoms (and terbutaline 0.25 mg injected subcutaneously in 2 of the 19 cases)]. 5 cases (15%) required reintubation and consequently returned back to the SICU with no diuretic being given prior to intubation. 100% of the stridorous population revealed bilateral crackles upon chest auscultation. Endotracheal tube cuff pressures averaged 17.09 cm H2O, LOI averaged 17.4 hours, and all laryngoscopies were atraumatic (as per anesthesia OR flow sheet).
Conclusions: IV furosemide along with acrosolized albuterol sulfate showed the greatest improvement in relief of symptoms over albuterol sulfate, racemic epinephrine, and ipratropium bromide alone. Stridor, by definition, was clinically identified noninvasively in all 33 cases. However, traumatic intubation, prolonged intubation, and excessive endotracheal tube cuff pressures were ruled out.