Suspension Syndrome

Study Overview
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Brief Summary
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Suspension syndrome refers to a potentially life-threatening condition that can occur in unconscious persons after prolonged suspension in a harness. To date, our understanding of the pathophysiology and appropriate treatment is based primarily on case reports and expert opinion. The main pathophysiological hypothesis implicates blood pooling in the lower extremity and lack of return via muscle pumping. However, a recent French study could not support this hypothesis. Other mechanisms, such as a central vagal reflex may play a role in the pathophysiology of suspension syndrome. The aim of this study is to better understand the pathophysiological basis of suspension syndrome and to develop practical recommendations for prevention and treatment.

Official Title
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Suspension Syndrome

Conditions
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Circulatory Collapse, Circulatory Failure, Syncope, Vasovagal, Neurally-Mediated, Orthostatic Hypotension

Intervention / Treatment
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* Other: Suspension in a harness
* Other: Climbing


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy volunteers Age 18-50 years ASA class 1 Signed informed consent Exclusion Criteria: Age <18 or >50 years ASA class >1 Informed consent not signed

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 50 Years

Sexes Eligible for Study
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Male

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Suspension without prior climbing<br>Free Suspension in a harness after baseline measurements and without prior climbing | Other: Suspension in a harness<br> <br> |
| Experimental: Suspension with prior climbing<br>Free Suspension in a harness after baseline measurements and after climbing in moderate intensity for 10 minutes | Other: Suspension in a harness<br> <br> Other: Climbing<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Heart rate |  | Change from baseline (measurement at minute 0) -> suspension phase (minute 10, timepoint immediately before interruption of suspension phase [max 60 minutes]) -> minute 5 and minute 15 after suspension phase | 
| Blood pressure |  | Change from baseline (measurement at minute 0) -> suspension phase (minute 10, timepoint immediately before interruption of suspension phase [max 60 minutes]) -> minute 5 and minute 15 after suspension phase | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in maximal Diameter of superficial femoral vein | Ultrasound measurement of the Diameter of the superficial femoral vein in millimeters | Change from baseline (measurement at minute 0) -> suspension phase (minute 10, timepoint immediately before interruption of suspension phase [max 60 minutes]) -> minute 5 and minute 15 after suspension phase | 
| Change in interbeat-interval | electrocardiographic measurement of interbeat interval in milliseconds (ms) | Change from baseline (measurement at minute 0) -> suspension phase (minute 10, timepoint immediately before interruption of suspension phase [max 60 minutes]) -> minute 5 and minute 15 after suspension phase |