www.buffalo.edu Autonomic function appears to be altered in concussed patients; especially when a physiological stressor is present. Heart rate variability (HRV) during whole body exercise is attenuated in concussed patients compared to healthy controls. However; HRV during isometric handgrip exercise has been shown to have a similar response between concussed patients and healthy controls. The cold pressor test (CPT) is an exercise independent test that could be used to identify shifts in autonomic function in concussed patients. We tested the hypothesis that heart rate and the root mean squared of successive differences (representing parasympathetic control) during the CPT in concussed patients is impaired versus healthy controls. We found that parasympathetic control of heart rate is not altered during the CPT in recently concussed patient. However; the blunted heart rate response does indicate that cardiac autonomic control is impaired in recently concussed patients. Heart Rate and Heart Rate Variability during the Cold PressorTest in Recently Concussed Patients Morgan C. O ’Leary, James R. Sackett, Zachary J. Schlader, John J. Leddy, and Blair D. Johnson Department of Exercise and Nutrition Sciences, University at Buffalo, Buffalo, NY, Department of Orthopedics, University at Buffalo, Buffalo, NY Funding Conclusions Abstract Background • There is conflicting evidence that heart rate variability (HRV) at rest is attenuated in concussion patients. • However, concussion patients have been shown to have attenuated HRV during physical stressors, such as hand grip exercise or whole body exercise, versus healthy controls. • Autonomic activation during exercise is reliant on several peripheral feedback mechanisms, which could be impaired in concussion patients. • The cold pressor test (CPT) is widely recognized as a general sympathoexcitatory test that could be easily used to assess autonomic function in concussed patients. • It is currently not known if HRV during the CPT in concussion patients is attenuated versus healthy controls. Purpose We tested the hypothesis that heart rate and the root mean squared of successive differences (RMSSD, which represents parasympathetic control) during the CPT in concussed patients is impaired versus healthy controls. Methods Subjects Concussion Patients : 8 patients diagnosed with a concussion by a physician (4 women; age 20±1) were tested 5±1 days post injury. Controls : 6 subjects (1 woman; age 25±4) were tested. These participants did not have had a history of suspected or confirmed concussion(s) within the last year. Measurements • Heart rate (ECG) • Visual Analogue Scale (VAS) Protocol • Subjects rested in the supine position for a 15 minute baseline period. • Subjects then submerged their right hand up to the wrist in an agitated ice/water slurry mixture (~1°C) for 120 seconds. Data Analysis • Data were analyzed for R to R Interval (RRI), Heart Rate (HR), and RMSSD Using WinCPRS in 60-second increments at baseline, 60 seconds and 120 seconds into the CPT, and 60 seconds post CPT. • Values reported are mean ± standard deviation • These preliminary data indicate that parasympathetic control of heart rate, represented by RMSSD, is not altered during the CPT in recently concussed patients. • However, the blunted heart rate response during the CPT does indicate that cardiac autonomic control is impaired in recently concussed patients. University at Buffalo Center for Undergraduate Research and Creative Activities Undergraduate Research Award Symptom Symptom Headache 4± 2 Difficulty remembering 2± 2 "Pressure in head" 2± 2 Fatigue or low energy 4± 2 Neck pain 1± 2 Confusion 2± 2 Nausea or vomiting 1± 1 Drowsiness 3± 2 Dizziness 2± 3 Trouble falling asleep 3± 2 Blurred Vision 2± 3 More emotional 2± 2 Balance problems 2± 3 Irritability 3± 2 Sensitivity to light 3± 2 Sadness 2± 2 Sensitivity to noise 2± 2 Nervous or anxious 2± 2 Feeling slowed down 3± 2 Worse with physical activity? 87.5% yes Feeling like "in a fog" 3± 2 Worse with mental activity? 87.5% yes "Don't feel right" 4± 2 Worse with stress? 87.5% yes Difficulty concentrating 3± 2 Results Baseline Symptom Severity *Scale: none= 0, mild=1-2, moderate=3-4, severe=5-6 Visual Analogue Scale (VAS) Values for symptom severity are from concussed patients only. Healthy subjects did not report any concussion symptoms * * * * *Different from Baseline (P < 0.05). Feel great, no symptoms Some symptoms but tolerable Symptoms a little worse Symptoms much worse Many symptoms Feel bad, worst I ever felt