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Presenter: Melina Bowdwin Mentor: Dr. David Pendergast

Negative Pressure Breathing to Enhance Nitrogen Elimination during DISSUB Rescue and other diving operations. CSTEP Oral Presentation July 18 th , 2012. Presenter: Melina Bowdwin Mentor: Dr. David Pendergast. Center for Research and Education in Special Environments (CRESE )

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Presenter: Melina Bowdwin Mentor: Dr. David Pendergast

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  1. Negative Pressure Breathing to Enhance Nitrogen Elimination during DISSUB Rescue and other diving operations. CSTEP Oral Presentation July 18th, 2012 Presenter: Melina Bowdwin Mentor: Dr. David Pendergast • Center for Research and Education in Special Environments (CRESE) • Department of Physiology and Biophysics, • University at Buffalo (SUNY)

  2. Overview • Significance of Negative Pressure Breathing and Nitrogen Elimination • Hypotheses • Methods & Materials and Experimental setup • A closer look at selected cardiovascular parameters • Conclusions and Summary

  3. Body nitrogen, What determines it, and why is elimination important: • The body is saturated with Nitrogen (78% air) • Atmospheric pressure changes should cause the body to give off nitrogen • Decompression sickness (DCS): N2 gas bubbles pressurizing nerves of the body • Increasing nitrogen elimination will decrease the risk of decompression sickness in astronauts and divers returning to the surface http://www.youtube.com/watch?v=lAyELTIM38g

  4. Hypotheses: • Negative pressure breathing (NPB) at -10 and -15 cmH2O performed by subjects while sitting erect at rest will enhance nitrogen elimination • This will result from an increase in cardiac output. Negative Pressure Breathing (NPB): volume of the thoracic cavity is increased, causing air to be forced into the lungs.

  5. Methods/Materials: • 8 healthy male subjects (18-35 yrs) • 2 types of mouthpieces: Continuous (inspiration and expiration) and intermittent (expiration, only) • 2 gas mixtures: Normoxic(21% oxygen in Argon) and 100% Oxygen • 2 negative pressures: -15 cmH2O and -10 cmH2O

  6. Subject sits in a 0% Nitrogen tent and is breathing on continuous mouthpiece. Monitor to the left of the subject records heart rate, blood pressure and cardiac output.

  7. Finapress sensor on the wrist measures CO Subject on finapres device Monitor records CO, HR, AND BP

  8. Sub-Project: Using Negative Pressure Breathing to Enhance Nitrogen Elimination and its Effect on Specific Cardiovascular Parameters.

  9. CO is increased significantly Cardiac output increased significantly from the control (normoxic and oxygen without NPB) in all conditions!

  10. CO increased due to an increase in Stroke Volume Blood pressure and heart rate did not statistically change from the control condition (no NPB) according to ANOVA for repeated measures (P≤0.05). The increase in CO was offset by a vasodilatation of blood vessels. This tells us that the increase in CO was due primarily to the increase in Stroke Volume!

  11. Summary/Conclusion • Negative pressure breathing enhances cardiac output. • Enhanced cardiac output plays a role in increasing nitrogen elimination. • Increasing nitrogen elimination leads to a decreased risk for DCS in divers and astronauts as well as a safer decompression to the surface!

  12. Acknowledgements • Funded by the Naval Sea Systems Command • Michael Fletcher, Research Technician • Lukas Eckhardt, Research Technician • David Pendergast, Ed.D (Mentor) • CSTEP Staff!!!

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