The Science Journal of the American Association for Respiratory Care

2001 OPEN FORUM Abstracts

CASEREPORT: A NON-INVASIVE TECHNIQUE OF HYPEROXIC HYPERCAPNIC CHALLENGE IN A PEDIATRICPATIENT

TimothyCox, RRT, Aaron Chidekel, M.D., John Rendle, RRT, Jeffery Malatack, M.D.;A. I. duPont Hospital for Children, Thomas Jefferson Medical College, Wilmington,De.

Introduction:If central neurological mechanisms are not depressed, tidal volume and frequencyof ventilation increase, when subjected to a rise in carbon dioxide tension(CO2). We describe a simple procedure using a respiratory profile monitor andgas supply of 5% CO2 / 95% O2 to assess the central neurologic response to anincreased level of CO2.

Case Summary:A 2.5 year old white male with global developmental delay was admitted due toquestionable episodes of seizure activity. The patient had a past medical historyof rigidity and cyanotic episodes since the age of two months age. Throughouthis life the patient was hospitalized for four previous admissions with episodes.A pulmonary consult was obtained to access respiratory control. In additionto polysomonogram a Hyperoxic Hypercapnic Challenge was performed using 5% CO2and 95% oxygen. After sedation with Chloral Hydrate, pulmonary mechanics wererecorded using a CO2SMO Plus, Respiratory Profile Monitor (Novametrix MedicalSystem, Inc., Wallingford, CT) and continuous cardiac and pulse oximetry monitoring.The procedure was performed in the Pediatric Intensive Care Unit with continuousattendance of two respiratory therapists, a sedation nurse and an attendingPediatric Pulmonlogist. A mask was used to create a seal although an intermittentleak was evident. As shown in the accompanying figures an appropriate responsein respiratory rate and minute ventilation was recorded in response to increasinglevels of end tidal CO2.

Discussion: Asimple technique originally introduced by Haldane and Smith in 1862, is basedon progressive increases in PaCO2 and resulting stimulation of ventilation,which occur during rebreathing. This method is rapid and simple, and thereforesuitable for clinical investigation. (Read, DJC: A Clinical Method for Assessingthe Ventilatory Response to Carbon Dioxide: Australas Ann Med, 1967 16(1):20-32).In resurrecting this simple screen with defined concentrations of CO2 (5%) andutilizing advanced technology to measure pulmonary mechanics and gas exchange,we facilitated a non- invasively assessment of respiratory control ina difficult pediatric patient.

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