I am presently undertaking two major areas of research.
- I am seeking to get a better insight into regulation of blood flow at the level of the capillaries and tissues, with an emphasis on assessing how this is controlled by the autonomic nervous system.
- Detecting when somebody is dehydrated or is losing blood before the change in volume status can cause significant harm to the body.
- New means of monitoring body temperature through a surface temperature monitor.
- Developing a common score for assessing the local impact of disorders, the systemic impact of disorders, and the impact of challenges such as surgery.
Extensive Research Description
1. Using a multi-dimensional computerized data acquisition system, we are integrating input from arterioles and capillaries (laser Doppler flowmetry), arteries and veins (plethysmography), with continuous monitors of blood pressure and heart rate to gain insight into two major areas of cardiovascular physiology: a) the regulation of microvascular perfusion, with a focus on autonomically-mediated autoregulatory processes; b) the assessment of the cardiovascular responses to volume loss intraoperatively and in healthy volunteers (withdrawal and reinfusion of two units of blood; simulated hypovolemia with the use of lower body negative pressure). These studies involve time-domain and spectral-domain analytical techniques in collaborative efforts with Cardiology, Emergency Medicine, Pulmonary Medicine, and Physiology at Yale and the J.B. Pierce Foundation as well as with Chairman of Biomedical Engineering at another institution. The work has led to intellectual property that has been transferred to Yale University School of Medicine.
2. In collaboration with Dr. Marc Abreu, the discoverer of the “brain temperature tunnel”, we have been determining the ability to monitor core and, more specifically, brain temperature, with a continuous sensor in the superiomedial orbit. We anticipate that this will have major impact with respect to continuous monitoring of core temperature and, more specifically, brain temperature.
3. I have introduced a new way for uniform scoring of bodily systems and the disorders affecting them and integrating this with the anticipated risks associated with anesthesia and surgery.1. Assessment of hemodynamic responses to lower body negative pressure with a focus on autoregulatory processes at the level of the cerebral circulation: comparison of systemic changes, mental status changes, transcranial Doppler, and laser Doppler flowmetry (in collaboration with other members of my Department as well as Nina Stachenfeld, Ph.D., Vahid Mohsenin, M.D., and Chris Moore, M.D.).
2. Assessment of the responses to withdrawal of two units of blood from healthy volunteers: We identified processes that are occurring prior to the development of hypotension and/or tachycardia.
3. Evaluation of continuous monitoring of core (and perhaps brain) temperature via the brain temperature tunnel at the superior medial orbit.
4. Application of the database we are collecting on patients scheduled for surgery who are seen in the Pre-Admission Testing Center.
- Silverman DG. Rosenbaum SH. Integrated assessment and consultation for the preoperative patient. Medical Clinics of North America. 93(5):963-977, 2009 Sep.
- Holt NF, Silverman DG: Modeling Perioperative Risk – Can Numbers Speak Louder Than Words? In: Rosenbaum SH (editor). Anesthesiology Clinics of NA 24:427-459, 2006
- Awad AA. Haddadin AS. Tantawy H. Badr TM. Stout RG. Silverman DG. Shelley KH. The relationship between the photoplethysmographic waveform and systemic vascular resistance. Journal of Clinical Monitoring & Computing. 21(6):365-72, 2007 Dec.
- Jablonka DH, Awad AA, Stout RG, Silverman DG, Shelley KH: Comparing the effect of arginine vasopressin on ear and finger photoplethysmography. Journal of Clinical Anesthesia 20:90-93, 2008
- Silverman DG, Stout RG: Distinction between atropine-sensitive control of microvascular and cardiac oscillatory activity. Microvasc Res 63:196-208, 2002
- Silverman DG, Jotkowitz AB, Freemer M, Gutter V, O'Connor TZ, Braverman IM: Peripheral assessment of phenylephrine-induced vasoconstriction by laser Doppler flowmetry and