Energy Expenditure Performing Hands-Only Cardiopulmonary Resuscitation During Average Emergency Response Times

Early cardiopulmonary resuscitation (CPR) by civilian responders is a critical aspect in the survival of cardiac arrest patients. According to the American Red Cross (ARC), the average response time to a 911 call is 8-12 min. High-quality CPR performed as soon as possible following cardiac arrest considerably increases a person’s chances of survival and recovery. It is possible that fatigue may decrease CPR quality, and to date no data exists on the metabolic cost of preforming hands-only CPR. PURPOSE: To determine the energy expenditure of performing hands-only CPR during the average emergency response time. METHODS: Eight college-aged participants (23.6 ± 4.6 years) with a current CPR certification from the ARC or American Heart Association (AHA) volunteered for the study. Anthropometric measurements were collected, participants were then fitted with a heart rate (HR) monitor. Indirect calorimetry was used to measure oxygen consumption and caloric expenditure during hands-only CPR for the minimum 8-minute response time. Participants were instructed to provide hands-only CPR to a manikin at a rate of 100-120 compressions per minute with a metronome (110 bpm) providing pacing. Descriptive statistics (mean ± SD) were evaluated for peak HR, peak metabolic equivalents (MET), estimated maximal HR, percent of maximal HR and caloric expenditure (kcals). RESULTS: Participants expended 33.3 ± 13.7 kcals when performing hands-only CPR for 8 minutes. Further, participants provided compressions at an intensity of 5.7 ± 1.5 METs. CONCLUSION: Our data suggest that the metabolic cost of performing hands-only CPR for the minimum 8-minute response time is comparable to the energy expenditure of a very brisk walk. One of the common reasons to discontinue CPR is that the responder is too exhausted to continue. The results of our study suggest it is unlikely that cardiorespiratory fatigue is the primary cause of exhaustion. Therefore, future research should aim to measure the energy expenditure of hands-only CPR to volitional exhaustion and identify perceived sources of fatigue

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements