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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.

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
Why? 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.

New input: Abstract: We assessed in ponies the adequacy of using rectal (Tre) rather than arterial temperature (Tar) under conditions common to ventilatory control experiments, i.e., CO2 breathing, thermal stress, and particularly exercise. We were interested in whether, and to what extent, Tar-Tre differences could lead to errors in arterial blood gas corrections. At control environmental temperatures (Ta) of 5 degrees C in the winter and 21 degrees C in the summer, Tar and Tre (37.1 degrees C) did not differ (P greater than 0.05). Elevating winter or summer Ta by 10-18 degrees C for 2-days or lowering summer Ta by 9 degrees C (2-days) did not change Tar or Tre (P greater than 0.05). Furthermore, elevating inspired PCO2 to 42 Torr for 15 min did not alter Tar or Tre from control (P greater than 0.05). During treadmill exercise, at 1.8 mph 5% grade, Tar and Tre did not change significantly (P greater than 0.05) from rest by 11 min of work. At 3 mph 5% grade, Tar increased progressively by 0.3 degrees C (P less than 0.05) while Tre tended to increase 0.1 degree C by 11 min. During moderate exercise at 6 mph 5% grade, Tar increased 0.9 degree C (P less than 0.05) while Tre increased 0.25 degree C (P less than 0.05). Finally, by 6 min of heavy exercise at 8 mph 20% grade, Tar increased 2 degrees C (P less than 0.05) while Tre increased 0.5 degree C (P less than 0.05). The Tar-Tre differences during the latter three work loads were statistically significant (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)
Solution:
Animal