The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts

A NEW DELIVERY CIRCUIT IN EVALUATING VASODILATOR RESPONSE OF INHALED NITRIC OXIDE IN PATIENTS WITH IDIOPATHIC PULMONARY ARTERIAL HYPERTENSION

Ching-Tzu Huang1, Lan-Ti Chou1, Hsiu-Feng Hsiao1, Chung-Chi Huang2,3, Kuo-Chin Kao2,3, Wan-Jing Ho4; 1Department of Respiratory Therapy, Chang Gung Memorial Hospital, Taoyuan, Taiwan; 2Division of Thoracic Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan; 3Department of Respiratory Care, Chang Gung University, Taoyuan, Taiwan; 4Department of Cardiology, Chang Gung Memorial Hospital, Taoyuan, Taiwan

Background: Idiopathic pulmonary arterial hypertension (IPAH) is a rare and devastating disease. Acute vasodilator test is important in selecting effective drugs of treatment in IPAH. A number of studies indicated that inhaled nitric oxide (iNO) can be safely and effectively used in assessing the response to the vasodilator, however there was no standard circuit for applying iNO. Here we propose a new iNO delivery circuit to evaluate the response of vasodilator in patients with IPAH during spontaneous breathing. METHOD: Idiopathic PAH patients were enrolled for the vasodilator test. Hemodynamic measurements were recorded by cardiac catheterization at baseline breathing room air and after breathing iNO. An INOvent delivered NO from source tanks to achieve proper dosing. With the patients breathing spontaneously, a NO and oxygen mixture was injected into the inspiratory limb of the circuit and delivered to the patient via a non-rebreathing mask. Flow rates were maintained at a rate greater than the patients’ minute ventilation through a one-way valve into a non-rebreathing facemask. All patients received iNO at doses of 10, 20, 40 and 80 ppm, or stopped at the dose with positive response. Five minutes was allowed at each iNO dose before hemodynamic assessment was undertaken. A positive response to vasodilator testing was defined as a decrease of mean pulmonary artery pressure (mPAP) >=10 mmHg to reach an absolute value of mPAP £40 mmHg with an increased or unchanged cardiac output. RESULTS: We studied 7 patients, including 4 females and 3 males, the average age was 35 ± 13 years. Two of 7 patients (28.6%) were positive response to iNO, and 5 patients were non-response (71.4%). Two patients were positive responder at 40ppm and 5 patients were non-responder even at 80ppm NO inhalation (Table). All of patients were tolerated the iNO test without adverse effects. CONCLUSION: This study revealed that this new delivery circuit can be effective and safe in evaluating vasodilator response of iNO in patients with IPAH. Sponsored Research - None

Acute vasodilator test with NO inhalation in patients with idiopathic pulmonary arterial hypertension

mPAP, mean pulmonary artery pressure; CI, cardiac index; CO, cardiac output; PVR, pulmonary vascular resistance; SVR, systemic vascular resistance.