Teacher: Given an abstract, generate a keyword (a noun phrase) that best describes the focus or contribution of the paper. Such keywords can be directly from the given abstract or outside it.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Abstract: Some patients converted from ventricular fibrillation to organized rhythms by defibrillation - trained ambulance technicians(EMT - Ds) will refibrillate before hospital arrival.The authors analyzed 271 cases of ventricular fibrillation managed by EMT - Ds working without paramedic back - up.Of 111 patients initially converted to organized rhythms, 19(17 % ) refibrillated, 11(58 % ) of whom were reconverted to perfusing rhythms, including nine of 11(82 % ) who had spontaneous pulses prior to refibrillation.Among patients initially converted to organized rhythms, hospital admission rates were lower for patients who refibrillated than for patients who did not(53 % versus 76 % , P = NS), although discharge rates were virtually identical(37 % and 35 % , respectively).Scene - to - hospital transport times were not predictively associated with either the frequency of refibrillation or patient outcome.Defibrillation - trained EMTs can effectively manage refibrillation with additional shocks and are not at a significant disadvantage when paramedic back - up is not available.
Solution: Ventricular Fibrillation
Reason: This term is directly present in the abstract and it is one of the main topic in it. So can be chosen as the medical subject heading.

Now, solve this instance: Abstract: The measurement of subjective pain intensity continues to be important to both researchers and clinicians. Although several scales are currently used to assess the intensity construct, it remains unclear which of these provides the most precise, replicable, and predictively valid measure. Five criteria for judging intensity scales have been considered in previous research: ease of administration of scoring; relative rates of incorrect responding; sensitivity as defined by the number of available response categories; sensitivity as defined by statistical power; and the magnitude of the relationship between each scale and a linear combination of pain intensity indices. In order to judge commonly used pain intensity measures, 75 chronic pain patients were asked to rate 4 kinds of pain (present, least, most, and average) using 6 scales. The utility and validity of the scales was judged using the criteria listed above. The results indicate that, for the present sample, the scales yield similar results in terms of the number of subjects who respond correctly to them and their predictive validity. However, when considering the remaining 3 criteria, the 101-point numerical rating scale appears to be the most practical index.
Student:
Adult