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The influence of skill level on snowboarding injuries
RESEARCH FORUM A B S T R A C T S
60
Fractal Versus Harmonic Components of Heart Rate in Atrial Tachyarrhythmias
Ruiz F. Ditto W. In V. Neff J/University of California-San Francisco, San FranciscoGeneral Hospital, San Francisco, CA; Georgia Institute of Technology.Atlanta. GA Variability in heart rate has both harmonic (oscillating) and nonharmonic (fractal) components. Study objective: We examined variability patterns m atrial tachyarrhythmias using coarse graining spectral analysis to characterize them as primarily fractal or harmonic and to generate hypotheses concerning rite use of those patterns in climcal practice Methods: We digitally recorded 15 minutes of heart rate tracings in i4 acutely ill emergency department patients with narrow complex tachycardias. Three patients had paroxysmal supraventricular tachycardia (PSVT), 1 had atrial flutter (AF1), 6 had atrial fibrillation (AF), and 4 had sinus tachycardia (ST). R-R intervals were precisely measured using a computerized technique that allows visual confirmation of each peak. Interval data was then subjected to coarse-graining spectral analysis to separate fractal from harmonic components. Results: Fractal components predominated in all 3 patients with PSVT (range 54% to 84%), all 4 patients with ST (range 75% to 88%), and a single patient with AF1 (67%). Patients in AF displayed a broader range, from a low of 43% to a high of 76% fractal. Conclusion: Heart rate variability patterns in ST, PSVT, and AF1 were all primarily fractal and failed to distinguish between the groups. Heart rate variabihty in AF was mathematically heterogeneous, with harmonic components predominating in some patients, suggesting the possibility of distinct clinical subgroups.
61
Resuscitation From Prolonged Ventricular Fibrillation and Induction of Selective Brain Hypothermia via Extracorporeal Bypass
Mori K. Saito J. TakeyamaY, Kurata Y, Itch Y, Elgas R, Renzi FP, Dickson E/Sappore Medical University, Sapporo,Japan; University of Massachusetts Medical School, Worcester, MA Restoration of coronary perfnsion by extracorporeal bypass may assist with the resurrection of normal cardiac activity after prolonged cardiac arrest. However, the central nervous system is less likely to recover in this setting. One technique, which has shown promise in improving neurologic recovery, is the induction of postresuscitative brain hypothermia. This study was conducted to determine whether extracorporeal bypass is capable of assisting in the return of spontaneous circulation and induction of brain hypothermia in a pig model of prolonged cardiac arrest. Methods: Venmcular fibrillation was reduced in common swine (n=12). After 20 minutes of cardiopulmonary arrest, femol~al venous/arterial extracorporeal bypass was instituted at a rate of 50 tnlA~g per minute. After 10 minutes of circulatory support, external defibrillation was attempted. On restoration of normal sinus rhythm, animals were randomized to receive either normothermia or selective brain hypothermia (SBH). Normothermic animals were maintained with ventilatory support and intervenous fluids for 24 hours. SBH pigs received 12 hours of femoral/carotid bypass at a rate of 5 mL/kg per minute at a temperature of 32~ The bypass temperature was then increased 1 degree per hour until reaching 37~ and continued at this temperature until completion of the protocol. Results: Normal sinus rhythm was restored m all animals at an average of 6.3 minutes after the venous/arterial bypass was started. Nasal temperature was used as a proven surrogate to direct brain temperate measurement. In control ammals, nasal temperature was greater than 37.0~ throughout the 24-hour recovery period. SBH animals bad a reduction of nasal temperature to 32.5~ 20 minutes after the institution of femoral/carotid bypass. This was maintained throughout the 12-hour cooling period without significantly affecting core temperature or hemodynamics. Nasal temperature slowly returned to normothermic levels during the second 12 hours of recovery. Pathology of the brains was then compared. Conclusion: Extracorporeal bypass was useful in restoring spontaneous circulation and reducing selective brain hypothermia m pigs with prolonged ventricular fibrillation.
362
Taxis Legislation. When Enforced, Impacts Seat Belt Use in Urban
Milzrnan D, Sammadar R, Sammadar C, Janchar T, Zlidenny A/Georgetown University Medical School, ProvidenceHospital, Washington, DC Study objective: Seat belt use in private vehicles currently approaches 60% and has been steadily increasing over the past 10 years, with enforcement resulting in
S 92
improved compliance. Few studies focused on the disparagingly low rates of safety restraint use in vehicles for hire. Methods: This was a prospective randomized survey conducted on passengers disembarking from taxis at airport and tram stations m a large urban setting over a 2-year period to include 1 year with and 1 year without enforcement of seat belt use for taxi riders. Responses were recorded using a 10-cm visual analog scale; researchers noted seat belt availability and use before questioning. Analysis included t test and %~; P<.05. Results: Four hundred seventy-nine passengers were included; 50.1% were male, and mean age was 40.4 years (95% confidence interval [CII 36.8 to 44.0). Actual belt use in taxis was 17%, not different from repotted regular use of 23% (P=NS), decreased from the reported use in private vehicles of 91.1% (95% CI 88.9 to 93.3; P<.01). After i year of enforced seat belt laws, an additional 443 passengers were resurveyed, with rider usage increasing to 31% versus 17% (P<.01). Use in private vehicles also increased to 95% versus 80% before legislation (P<.03). Conclusion: Without laws enforcing use, most taxi riders do not wear seat belts even though the) practice fair compliance in their private vehicles. However, when laws were enforced, seat belt usage increased significantly not only in cabs but also m private vehicles.
363
The Influence of Skill Level on Snowboarding Injuries
Janchar T. Zlidenny A, Coury T. Milzman D, PaluskaT/Georgetown University School of Medicine, ProvidenceHospital. Washington, DC Snowboarding is one of most rapidly growing winter sports with a proportional rise m associated injuries. With several thousand people learning to snowboard each year, there is a wide range in the skill levels of riders on the slopes; these differences in skill level have a potential influence on both the location and frequency of injuries seen Study objective: To determine the influence of skill level on snowboarding injuries. Methods: This study is a retrospective analysis of injuries seen at the medical clinic of Big Sky Resort (Big Sky, MT) over 2 years. Patients filled out study surveys after presenting to the clinic. Skill level was evaluated as beginner (first day or first weeD, intermediate (early intermediate or advanced intermediate), and expert (expert or extreme). Data were then analyzed by the authors using Epistat software. Results: Over the 2 years, 539,000 skier/snowboarder days were reported with 812 patients presenting to the clinic for evaluation. Of these patients, 144 (19%) had injuries related to snowboardmg. The average age of the injured snowboarder was 19.9 years with 73% being male. Of those injured, the skill levels were as follows: 48 (33%) were beginner, 23 (16%) were early intermediate, 41 (28%) were advanced intermediate, 26 (18%) were expert, and 6 (4%) were extreme. Wrist injuries predominated in the beginner group with 41% of injuries in this group being wrist-related versus 14% in the expert group (P<.05) and 34% in the intermediates (P=NS). Shoulder injuries predominated in the intermediate group with 38% of the injuries shoulder-related versus 21% in the expert group (P<.05) and 26% in the beginners (P=NS). Head injuries predominated in the expert group with 36% of the injuries m this group head-related versus 15% in the beginners (P=NS) and 16% in the intermediate group (P=NS). Age and gender data ranges were too narrow to draw any significant correlations between injury mechanisms. Discussion: Overall, more injuries were seen in the beginner group. Comparisons drawn were the predominance of wrist injuries in beginners, shoulder injuries in the intermediate group, and head injuries in the expert group. The high rate of wrist injuries in beginners can be explained by the tendency for these riders to fall on outstretched arms to break falls. As riders' balance and skill improve, they move to more difficult terrain and are more likely to attempt more dangerous jumps and moves increasing the susceptibility to head injuries. Precautions that can be taken include more educational classes and lessons for beginners and the use of helmets and protective gear for aII riders, especialty those on more ditt~cuft terrain or attempting jumps or difficult moves
364
Parental Report of Child Restraint Device Use in an Emergency Department Population
Funk DL, McErlean M, Verdile VP/Albany Medical College, Albany, NY Study objective: To survey parents regarding their use of child restraint devices (CRD) and knowledge of CRD recommendations. Methods: Parents of children 14 years or younger presenting to a university tertiary care children's hospital emergency department from November 4 through December 3, 1998, were surveyed as a convenience sample. Parents were asked to provide demo-
ANNALS OF EMERGENCY MEDICINE 34:4 OCTOBER 1999, PART2
60
Fractal Versus Harmonic Components of Heart Rate in Atrial Tachyarrhythmias
Ruiz F. Ditto W. In V. Neff J/University of California-San Francisco, San FranciscoGeneral Hospital, San Francisco, CA; Georgia Institute of Technology.Atlanta. GA Variability in heart rate has both harmonic (oscillating) and nonharmonic (fractal) components. Study objective: We examined variability patterns m atrial tachyarrhythmias using coarse graining spectral analysis to characterize them as primarily fractal or harmonic and to generate hypotheses concerning rite use of those patterns in climcal practice Methods: We digitally recorded 15 minutes of heart rate tracings in i4 acutely ill emergency department patients with narrow complex tachycardias. Three patients had paroxysmal supraventricular tachycardia (PSVT), 1 had atrial flutter (AF1), 6 had atrial fibrillation (AF), and 4 had sinus tachycardia (ST). R-R intervals were precisely measured using a computerized technique that allows visual confirmation of each peak. Interval data was then subjected to coarse-graining spectral analysis to separate fractal from harmonic components. Results: Fractal components predominated in all 3 patients with PSVT (range 54% to 84%), all 4 patients with ST (range 75% to 88%), and a single patient with AF1 (67%). Patients in AF displayed a broader range, from a low of 43% to a high of 76% fractal. Conclusion: Heart rate variability patterns in ST, PSVT, and AF1 were all primarily fractal and failed to distinguish between the groups. Heart rate variabihty in AF was mathematically heterogeneous, with harmonic components predominating in some patients, suggesting the possibility of distinct clinical subgroups.
61
Resuscitation From Prolonged Ventricular Fibrillation and Induction of Selective Brain Hypothermia via Extracorporeal Bypass
Mori K. Saito J. TakeyamaY, Kurata Y, Itch Y, Elgas R, Renzi FP, Dickson E/Sappore Medical University, Sapporo,Japan; University of Massachusetts Medical School, Worcester, MA Restoration of coronary perfnsion by extracorporeal bypass may assist with the resurrection of normal cardiac activity after prolonged cardiac arrest. However, the central nervous system is less likely to recover in this setting. One technique, which has shown promise in improving neurologic recovery, is the induction of postresuscitative brain hypothermia. This study was conducted to determine whether extracorporeal bypass is capable of assisting in the return of spontaneous circulation and induction of brain hypothermia in a pig model of prolonged cardiac arrest. Methods: Venmcular fibrillation was reduced in common swine (n=12). After 20 minutes of cardiopulmonary arrest, femol~al venous/arterial extracorporeal bypass was instituted at a rate of 50 tnlA~g per minute. After 10 minutes of circulatory support, external defibrillation was attempted. On restoration of normal sinus rhythm, animals were randomized to receive either normothermia or selective brain hypothermia (SBH). Normothermic animals were maintained with ventilatory support and intervenous fluids for 24 hours. SBH pigs received 12 hours of femoral/carotid bypass at a rate of 5 mL/kg per minute at a temperature of 32~ The bypass temperature was then increased 1 degree per hour until reaching 37~ and continued at this temperature until completion of the protocol. Results: Normal sinus rhythm was restored m all animals at an average of 6.3 minutes after the venous/arterial bypass was started. Nasal temperature was used as a proven surrogate to direct brain temperate measurement. In control ammals, nasal temperature was greater than 37.0~ throughout the 24-hour recovery period. SBH animals bad a reduction of nasal temperature to 32.5~ 20 minutes after the institution of femoral/carotid bypass. This was maintained throughout the 12-hour cooling period without significantly affecting core temperature or hemodynamics. Nasal temperature slowly returned to normothermic levels during the second 12 hours of recovery. Pathology of the brains was then compared. Conclusion: Extracorporeal bypass was useful in restoring spontaneous circulation and reducing selective brain hypothermia m pigs with prolonged ventricular fibrillation.
362
Taxis Legislation. When Enforced, Impacts Seat Belt Use in Urban
Milzrnan D, Sammadar R, Sammadar C, Janchar T, Zlidenny A/Georgetown University Medical School, ProvidenceHospital, Washington, DC Study objective: Seat belt use in private vehicles currently approaches 60% and has been steadily increasing over the past 10 years, with enforcement resulting in
S 92
improved compliance. Few studies focused on the disparagingly low rates of safety restraint use in vehicles for hire. Methods: This was a prospective randomized survey conducted on passengers disembarking from taxis at airport and tram stations m a large urban setting over a 2-year period to include 1 year with and 1 year without enforcement of seat belt use for taxi riders. Responses were recorded using a 10-cm visual analog scale; researchers noted seat belt availability and use before questioning. Analysis included t test and %~; P<.05. Results: Four hundred seventy-nine passengers were included; 50.1% were male, and mean age was 40.4 years (95% confidence interval [CII 36.8 to 44.0). Actual belt use in taxis was 17%, not different from repotted regular use of 23% (P=NS), decreased from the reported use in private vehicles of 91.1% (95% CI 88.9 to 93.3; P<.01). After i year of enforced seat belt laws, an additional 443 passengers were resurveyed, with rider usage increasing to 31% versus 17% (P<.01). Use in private vehicles also increased to 95% versus 80% before legislation (P<.03). Conclusion: Without laws enforcing use, most taxi riders do not wear seat belts even though the) practice fair compliance in their private vehicles. However, when laws were enforced, seat belt usage increased significantly not only in cabs but also m private vehicles.
363
The Influence of Skill Level on Snowboarding Injuries
Janchar T. Zlidenny A, Coury T. Milzman D, PaluskaT/Georgetown University School of Medicine, ProvidenceHospital. Washington, DC Snowboarding is one of most rapidly growing winter sports with a proportional rise m associated injuries. With several thousand people learning to snowboard each year, there is a wide range in the skill levels of riders on the slopes; these differences in skill level have a potential influence on both the location and frequency of injuries seen Study objective: To determine the influence of skill level on snowboarding injuries. Methods: This study is a retrospective analysis of injuries seen at the medical clinic of Big Sky Resort (Big Sky, MT) over 2 years. Patients filled out study surveys after presenting to the clinic. Skill level was evaluated as beginner (first day or first weeD, intermediate (early intermediate or advanced intermediate), and expert (expert or extreme). Data were then analyzed by the authors using Epistat software. Results: Over the 2 years, 539,000 skier/snowboarder days were reported with 812 patients presenting to the clinic for evaluation. Of these patients, 144 (19%) had injuries related to snowboardmg. The average age of the injured snowboarder was 19.9 years with 73% being male. Of those injured, the skill levels were as follows: 48 (33%) were beginner, 23 (16%) were early intermediate, 41 (28%) were advanced intermediate, 26 (18%) were expert, and 6 (4%) were extreme. Wrist injuries predominated in the beginner group with 41% of injuries in this group being wrist-related versus 14% in the expert group (P<.05) and 34% in the intermediates (P=NS). Shoulder injuries predominated in the intermediate group with 38% of the injuries shoulder-related versus 21% in the expert group (P<.05) and 26% in the beginners (P=NS). Head injuries predominated in the expert group with 36% of the injuries m this group head-related versus 15% in the beginners (P=NS) and 16% in the intermediate group (P=NS). Age and gender data ranges were too narrow to draw any significant correlations between injury mechanisms. Discussion: Overall, more injuries were seen in the beginner group. Comparisons drawn were the predominance of wrist injuries in beginners, shoulder injuries in the intermediate group, and head injuries in the expert group. The high rate of wrist injuries in beginners can be explained by the tendency for these riders to fall on outstretched arms to break falls. As riders' balance and skill improve, they move to more difficult terrain and are more likely to attempt more dangerous jumps and moves increasing the susceptibility to head injuries. Precautions that can be taken include more educational classes and lessons for beginners and the use of helmets and protective gear for aII riders, especialty those on more ditt~cuft terrain or attempting jumps or difficult moves
364
Parental Report of Child Restraint Device Use in an Emergency Department Population
Funk DL, McErlean M, Verdile VP/Albany Medical College, Albany, NY Study objective: To survey parents regarding their use of child restraint devices (CRD) and knowledge of CRD recommendations. Methods: Parents of children 14 years or younger presenting to a university tertiary care children's hospital emergency department from November 4 through December 3, 1998, were surveyed as a convenience sample. Parents were asked to provide demo-
ANNALS OF EMERGENCY MEDICINE 34:4 OCTOBER 1999, PART2