Study investigators have retracted an earlier report that N95 respirators prevent flu transmission better than surgical masks (see November 2009 Research Monitor, page 132). Re-analysis of study data showed no significant between-mask differences in flu transmission, co-investigator Holly Seale, Ph.D., from the University of New South Wales in Sydney, Australia, reported at the Infectious Diseases Society of America in October 2009.
Unfortunately, the original and now apparently erroneous findings helped form the Institute of Medicine, Centers for Disease Control and Prevention, and Occupational Safety and Health Administration recommendations that health care workers use the more expensive and less widely available N95 respirator when treating H1N1 patients. In response, the Society for Healthcare Epidemiology of America, Infectious Diseases Society of America, and the Association of Professionals in Infection Control and Epidemiology have urged modified federal guidance on personal protective equipment needs during H1N1 patient care. To view their statements, visit shea-online.org/Assets/files/policy/Obama_Letter.pdf. — MedPage Today Oct. 31, 2009, and Nov. 2, 2009; Medical News Today Nov. 8, 2009.
Editor’s note: Study findings reported at medical meetings should generally be considered preliminary, as this issue demonstrates. Research Monitor covers study findings only to keep readers informed of research issues that may potentially impact the management of emergency services.
Some conference reports of EMS-notable, but preliminary, study findings include:
- Resuscitation Outcomes Consortium investigators reported that audible, automated CPR coaching vs. no voice prompting modestly improved EMS delivery of AHA-compliant CPR. But voice vs. no prompts did not result in statistical differences in return of spontaneous circulation (48 vs. just under 49 percent, respectively) or survival to hospital discharge (11 vs. 12 percent, respectively) among 1,521 patients treated over 25 months.
- The University of Arizona Sarver Heart Center and the Save Hearts in Arizona Research and Education programs reported that their state’s bystander CPR rose from 25 percent in 2005 to 34 percent during the first quarter of 2009. During this period, continuous chest compression (CCC) CPR among lay-providers increased from 16 to 77 percent. Patient survival to hospital discharge was higher among those who received CCC vs. standard CPR.
- Fifteen European EMS systems trained in an intranasal brain-cooling procedure, preferably within 10 minutes of initiating CPR, reported that 59 percent of chilled vs. 29 percent of non-chilled patients survived to hospital discharge. Good neurological function at discharge was also reported in just under 46 vs. 18 percent of patients, respectively.
- The Richmond Ambulance Authority and Virginia Commonwealth University Medical Center reported that survival to hospital discharge rates rose from just fewer than 10 percent in 2001 to nearly 18 percent by the end of 2008 for patients suffering out-of-hospital cardiac arrest. During this time, return of spontaneous circulation rates rose from 25 to 46 percent. Ambulance and hospital spokespeople cite the area’s efficient 911 system; use of prehospital IV drugs; high-quality, mechanically delivered CPR; and prehospital initiation of patient cooling with cold saline that is continued in-hospital as factors leading to improved patient survival.
To view the findings, visit scientificsessions.americanheart.org/portal/scientificsessions/ss/resuscitationsciencesymposium2009.
Unplanned development may increase ambulance response times. Matthew J. Trowbridge, M.D., and colleagues at the University of Virginia in Charlottesville measured commercial and residential density in areas surrounding more than 43,000 motor vehicle accidents. Accounting for time of day, weather and the presence of construction, the researchers found that in 69 percent of the sprawl-area crashes, ambulances took more than eight minutes to arrive on scene. They took that long in just 31 percent of areas that better regulated development. The use of smart community growth and design regulations may improve EMS response, the researchers conclude. — American Journal of Preventive Medicine 37(5):428–432, November 2009.
When working a night shift, don’t reach for a cup-a-java or caffeine drinks and then expect to get a good day’s sleep. Professor Julie Carrier and colleagues at the Hospital du Sacre–Coeur Sleep Disorders Center in Montreal assessed daytime recovery sleep in 24 men and women after 25 hours of wakefulness. The subjects had either had no caffeine or a dose of 200 milligrams of caffeine on two separate sleep-assessment occasions. While quality sleep time declined for all after having caffeine, the 45- to 60-year-old participants slept 50 percent less than the 20- to 30-year-old group. — Sleep Medicine 10(9):1016–1024, October 2009.
Lack of benefit or harm caused the National Heart, Lung and Blood Institute and an independent monitoring board to halt further enrollment in a prehospital study of CPR methods. The PRIMED study (Prehospital Resuscitation Using an Impedance Valve and Early Versus Delayed) looked at patient outcomes after no use or use of an impedance threshold device that, in animals, enhanced intra-chest pressure and circulation during CPR. The study also assessed patient outcomes after EMS-delivered CPR for 30 seconds or three minutes before evaluating the need for defibrillation. The Resuscitation Outcomes Consortium investigators will continue to monitor long-term outcomes of the 11,500 study participants and plan to publish their observations in the near future. — Medical News Today, Nov. 9, 2009.
ACLS-delivered IV epinephrine may not benefit out-of-hospital cardiac arrest patients, researchers from Norway have found. Survival to hospital discharge was 10.5 percent (44 of 418 patients) in the epinephrine vs. 9.2 percent (40 of 433 patients) in the no-epinephrine groups. Allowing for ventricular fibrillation, response interval, witnessed arrest or arrest in a public place, researchers report corresponding survival rates at one year of 9.8 and 8.4 percent. Theresa M. Olasveengen, M.D., at Oslo University Hospital, and co-investigators call for further investigations of the efficacy of epinephrine and other prehospital IV treatments in larger groups of patients. — Journal of the American Medical Association 302(20):2222–2229, Nov. 25, 2009.
Twenty-eight police trainees (including four women) showed no adverse cardiac events from three separate, five-second Taser zaps, reported William P. Bozeman, M.D., and colleagues at Wake Forest University School of Medicine in Winston Salem, N.C. The volunteers’ heart rates increased almost 11 beats per minute, and systolic and diastolic BP readings rose about three points each on average, but they had no cardiac dysrhythmias or aberrant heartbeats from the zaps. — Emergency Medicine Journal 26(8):567–570, August 2009.
— Joene Hendry, contributing writer
