You will be shown an abstract from a biomedical research paper. Given this abstract, your task is to extract all unique entities of the following types: ["Outcome", "Participant", "Intervention"].

Please return the output as a JSON object of the format: {"Participant" : ["patients with COPD", ...], "Intervention" : ["Atenolol", ...], "Outcome" : ["blood pressure", ...]}. The keys should be entity types and values should be lists of extracted entities belonging to the corresponding type. If you cannot find entities belonging to a specific type, the value should be [].

Only output the JSON object and do not include any additional text.

Abstract:

A Double-Blind Placebo-Controlled Study of the Effects of Olprinone , a Specific Phosphodiesterase III Inhibitor , for Preventing Postoperative Atrial Fibrillation in Patients Undergoing Pulmonary Resection for Lung Cancer . BACKGROUND We previously reported that patients with elevated preoperative B-type natriuretic peptide ( BNP ) levels have an increased risk for postoperative atrial fibrillation following lung cancer surgery . The present study evaluated whether the specific phosphodiesterase III inhibitor olprinone can reduce the incidence of postoperative atrial fibrillation in patients with elevated BNP levels undergoing pulmonary resection for lung cancer . METHODS A prospective randomized study was conducted with 40 patients who had elevated preoperative BNP levels ( ≥ 30 pg/mL ) and underwent scheduled lung cancer surgery . All patients were in sinus rhythm at surgery . Low-dose olprinone or placebo was continuously infused for 24 h and started just before anesthesia induction . The primary end point was the incidence of postoperative atrial fibrillation . The secondary end points were perioperative hemodynamics and levels of BNP , WBC counts , and C-reactive protein . RESULTS The incidence of postoperative atrial fibrillation was significantly lower in the olprinone group than in the placebo group ( 10 % vs 60 % , P < .001 ) . Patients in the olprinone group showed significantly lower BNP , WBC counts , and C-reactive protein levels after surgery . CONCLUSIONS Continuous infusion of olprinone during lung cancer surgery was safe and reduced the incidence of postoperative atrial fibrillation following pulmonary resection in patients with elevated preoperative BNP levels . TRIAL REGISTRY Japan Primary Registries Network ; No . : JPRN-UMIN2404 ; URL : http : //www.umin.ac.jp/ctr/ .
{"Intervention": ["Olprinone", "Placebo-Controlled", "olprinone"], "Outcome": [], "Participant": []}