Continuous Noninvasive Measurement of Pulsus Paradoxus Complements Medical Decision Making in Assessment of Acute Asthma Severity: Prospective Cohort
Patients and Protocol: Adult patients who were 18 to 70 years of age, had a documented history of asthma, and were presenting with shortness of breath and probable asthma exacerbation were approached for study enrollment by trained clinical research assistants. Informed consent was obtained during the ED triage process or shortly thereafter, before ED treatment was initiated. Following patient consent, ED treatment was standardized and completed within 60 min according to NAEPP guidelines, as follows: three sequential nebulized albuterol treatments; and either IV solumedrol, 125 mg, or oral prednisone, 60 mg. Just prior to the initiation of ED treatment and at the end of ED treatment, patients’ AT-PP was measured, and both the treating physician and another physician performed objective asthma scoring. Physicians were blinded to the AT-PP values. Research assistants also measured patient vital signs during the AT-PP measurements. Following treatment, patient disposition was determined by the treating emergency physician, who was blinded to AT-PP measurements. A poor outcome was defined as either patient admission to the hospital or the relapse of a patient who had been discharged from the hospital within 72 h. All patients discharged from the hospital were contacted to determine whether they had made an unscheduled visit for their asthma exacerbation after ED discharge. This study was reviewed and approved by the Institutional Review Board.
The medical records of enrolled patients were analyzed to confirm that a prior diagnosis of asthma existed. Among patients who were admitted to the hospital, a physician who was blinded to AT-PP values and the ED record audited all inpatient records. Patients who had been inappropriately admitted to the hospital were identified as those whose level of care could have been accomplished as an outpatient. These patients were treated with oral steroids and metered-dose inhalers, and were not aggressively monitored.
Physician Objective Scoring: Both physicians assessed each patient using eight visual analog scales measuring the following: accessory muscle use; wheezing; prolonged expiratory phase; objective dyspnea (OD); air entry; cyanosis; sternocleidomastoid muscle use; and mental status. Each scale ranged from 0 to 3, with anchor points at each integer. All of the scales were on the same side of a single sheet of paper. The physicians completed this assessment sequentially and filled in the form separately.
They were instructed to mark the visual analog scale with an “X” along the continuum that best reflected the patients’ conditions for each of the above physical examination findings. The scoring of these data was accomplished with a ruler, measuring the distance of the X from the origin for each scale.