From Outcomes Measure in Research to Daily Rehabilitation Practice-Heart Rate Variability

 

Chair

Michal Katz-Leurer

Presenters:

Michal Katz-Leurer
Hemda Rotem
Nurit Stern
Simon-Henri Schless

 

Description:

Traumatic brain injury (TBI) is the main cause of long-term disability in children and young adults. Children post severe TBI have a low tolerance for physical activity when compared with healthy peers which is often explained by the impaired motor abilities and or sedentary behavior post injury. Although less discussed, an impaired autonomic heart regulation system is frequently experienced by children post TBI with hyper stimulation of the sympathetic nervous system. This impairment might be associated with or even be the cause of the observed reduced tolerance.

The cardiac autonomic regulation system frequently assesses using the Heart rate variability (HRV) parameters. HRV present the dynamic interplay between multiple physiologic mechanisms that regulate the instantaneous HR and reflect the heart’s ability to adapt to changing circumstances. HRV is a useful signal for understanding the status of the autonomic nervous system (ANS). The balancing action of the sympathetic nervous system (SNS) and parasympathetic nervous system (PNS) branches of the autonomic nervous system (ANS) controls the HR.

In a study assessed the cardiac autonomic system in children 2.5 years (range 1-5) post injury, the autonomic regulation system presents higher sympathetic tone at rest. The HR values of children post TBI were 1.3 times higher as compared to TD controls (p<0.01) and the instantaneous HRV measure was lower by 0.51 times (p=0.04). In addition, an interaction effect was noted during activity; while almost no change in HR and HRV was noted in children post TBI, a remarkable increase in HR (p<0.01) and decrease in HRV was noted in the controls (p<0.05), which represent lower autonomic adaptation to treadmill walking for 6 minutes.

Two years later, only two children were regularly physically active, and the same trend of autonomic impairment was noted. At rest the HR of children TD was 80±8 bpm, while in children post TBI 101±12 bpm. The long-term measure of HRV was lower by 0.73 fold, and the short term measure of HRV was low by 0.69 fold as compared to TD age and gender matched controls which again represent higher sympathetic tone at rest. In a next stage the children were asked to walk on a treadmill for 6 minutes in their comfortable walking velocity and significant interaction was noted, while children with TD perform the task their HR increased and their HRV decrease significantly more as compared to the change in these values in children post TBI.

Taking these outcomes to clinic reveal two main intervention: the first associate with continues assessment of the autonomic system during treatment in seeking interventions that may from one side reduced rest hyper sympathetic tone and on the other hand activities which stimulate the autonomic system. The second is in establishing two high aerobic programs for these children; one is “a long distance adapted bicycle activity group” the second is the “running for long distance” group. HR and HRV constantly assessed before during and after activities.

The main aerobic program structure and follow up, in particular the HRV measures as a tool for assessment, ruling exercise structure and progress will be present.

 

 

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