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:

Epidural fentanyl-bupivacaine compared with clonidine-bupivacaine for analgesia in labour . Alpha-adrenergic agonists produce pain relief through an opioid independent mechanism and may be alternatives to opioids for combination with local anaesthetics for analgesia during labour . We studied 41 pregnant women . Epidural block was performed with 75 microg clonidine ( n = 20 ) or 50 microg fentanyl ( n = 21 ) combined with 0.125 % bupivacaine ( 10 mL ) . Maternal vital parameters were measured . Analgesia was evaluated using a visual analogue scale ( VAS ) ; sedation was scored using a five-point scale . There were no differences in maternal vital parameters , fetal heart rate ( FHR ) or Apgar scores between the groups . Analgesia lasted longer in the bupivacaine-clonidine group ( 139.4 +/- 31 min ) compared with the bupivacaine-fentanyl group ( 127.9 +/- 48 min ) ( P = 0.42 ) . Additional analgesic requirement was more often in the fentanyl-bupivacaine group and total bupivacaine requirement was less in the clonidine-bupivacaine group ( 22.5 +/- 12.5 mg vs. 30.9 +/- 12.8 mg ) ( P = 0.04 ) . This small study confirms that this combination of bupivacaine and clonidine provides satisfactory analgesia for first-stage labour , and of longer duration than bupivacaine-fentanyl .
{"Intervention": ["combined with 0.125 % bupivacaine", "bupivacaine-fentanyl", "bupivacaine", "bupivacaine-clonidine", "clonidine", "fentanyl-bupivacaine", "Epidural fentanyl-bupivacaine", "clonidine-bupivacaine", "50 microg fentanyl"], "Outcome": ["sedation", "maternal vital parameters , fetal heart rate ( FHR ) or Apgar scores", "Analgesia", "satisfactory analgesia", "duration", "Maternal vital parameters", "Additional analgesic requirement", "pain relief"], "Participant": ["women", "41", "analgesia in labour"]}