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CEREBRAL RESUSCITATION PAPER COMPETITION The following two abstracts were the finalists for the Cerebral Resuscitation Paper Competition at the National Association of EMS Physicians Annual Meeting, January 10,1998, Ft. Lauderdale, Florida. Names of presenters are shown in boldface type.

THE EFFECTS OF NORMOXIC VENTILATION ON NEUROLOGIC OUTCOME AFTER CARDIAC ARREST IN RATS

AUTHORS:

AFFILIATIONS:

CHRISTOPHER A. LIPINSKI, MD CLIFTON W. CALLAWAY, MD, PHD SHAWN D. HICKS, BS, EMT-P

DEPARTMENT OF EMERGENCY MEDICINE, UNIVERSITY OF MEDICINE, PITTSBURGH, PENNSYLVANIA UNIVERSITY OF PITTSBURGH, SCHOOL OF MEDICINE CENTER FOR EMERGENCY MEDICINE OF WESTERN PENNSYLVANIA

OBJECTIVE: Reducing oxygen tension during reperfusion after cerebral ischemia may reduce formation of reactive oxygen species and brain injury. This study examined the influence of normoxic (FiO, = 0.21) vs hyperoxic (FiO, = 1.0) ventilation on neurologic outcome for 72 hours after cardiac arrest and resuscitation in rats.

METHODS: Under halothane anesthesia, asphyxia was induced in mechanically ventilated, paralyzed, male rats. Asphyxia produced cardiac arrest within 200 seconds. After 8 minutes, circulation was restored by reinstitution of normoxic (n = 9) or hyperoxic (n = 7) ventilation, performing chest compressions, and administering epinephrine and bicarbonate. Neurologic deficit scores (NDS) (0 = no deficit, 100 = brain death) were determined for each animal at 24,48, and 72 hours. Histologic damage at 72 hours (Nissl-stained sections) was ascertained in the CAI, CA2, and CA3 areas of the hippocampus and compared with the more robust neurons of the hippocampal dentate (total cells per high-powered field and dead vs live cells).

RESULTS: The NDS did not differ statistically between the normoxic (26.6 2 2.5, 16.6 2 6.0, and 15.0 5 5.0) and the hyperoxic (23.7 -C 6.2,18.7 5 3.4, and 21.2 ? 7.7) groups at any time point. Animals included in the analysis did not differ statistically in any hemodynamic parameter. The PaO, differed statistically between groups (p > 0.001) as expected, but there was no difference in the pH, pCO,, BE, and HCO,. There was no difference in histologic injury in any hippocampal subpopulation.

CONCLUSION: Normoxic ventilation during resuscitation from cardiac arrest does not substantially improve 72-hour outcome in rats. The equality of histologic damage between groups serves to substantiate these findings.

This competition was supported by Genentech, Inc.

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CEREBRAL RESUSCITATION ABSTRACTS 165

THE IMPACT OF STROKE SEVERITY AND DURATION OF

SYMPTOMS IN ACCESSING E M S

AUTHORS: E. DAVID BAILEY, MD ROBERT E. O'CONNOR, MD, MPH KELLY A. BAILEY, BSN

AFFILIATION: DEPARTMENT OF EMERGENCY MEDICINE, MEDICAL CENTER OF DELAWARE, NEWARK, DELAWARE

OBJECTIVE: Thrombolytic therapy in the treatment of stroke is restricted to the first three hours following symptom onset, making access to care a critical step in treatment. This study was an attempt to identify factors associated with EMS access by stroke patients.

METHODS: This study was conducted by retrospective emergency department (ED) chart review of consecutive patients with an ICD-9 code of stroke from September 1,1996, to April 30,1997. Information abstracted from the charts included mode of arrival (MOA; EMS or other), NIH stroke scale (NIHSS), CT scan abnormalities, time interval from symptom onset to ED arrival (onset:ED), and time from arrival until seen by a physician (ED:PHY). Patients transferred from other facilities were excluded. Statistical analysis employed chi-square, Mann-Whitney test, and the t-test.

RESULTS: A total of 239 charts were evaluated, and the following results were tabulated:

MOA NIHSS 0nset:ED (hr) ( 1 3 hr) EDPHY (min)

EMS (n = 145) 7.44 23.9 52% 40.5 Other (n = 94) 3.32 27.2 21 % 56.7

p-value <0.00001 Not significant <0.000001 0.003

There was poor correlation between NIHSS and onset:ED interval (r2 = O.OOS), between NIHSS and ED:PHY (r2 = 0.07), and between onset:ED and ED:PHY (9 = 0.02). The mean NIHSS was significantly higher for those arriving before, compared with those arriving after, three hours (6.9 vs 5.1; p = 0.001).

CONCLUSIONS: Stroke patients arriving by ambulance had significantly higher NIHSS scores, were seen more quickly, but did not seek treatment any sooner than those arriving by other means. Even though there was no difference between the two MOA groups in average duration of symptoms prior to presentation, a greater percentage of the ambulance group arrived within three hours of symptom onset. Additional efforts should be made to educate the public to recognize the symptoms of stroke and access care in a timely fashion.

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