Session C - Decompression Theory and Mechanisms

Plenary: Why Flight Surgeons Also Worry About DCS

Speaker: Michael Harrison, MD
Time: 8:00 am - 8:55 am

HarrisonAbout the Lecture:
Decompression sickness (DCS) is commonly associated with diving and other underwater activities. However, DCS can occur in any setting where a change in barometric pressure occurs in the presence of an inert gas. In diving, DCS typically occurs after surfacing from depth and the gold standard of treatment is often recompression in a hyperbaric chamber. Flight surgeons are charged with caring for the pilots and passengers of any number of flying vehicles ranging from hot air balloons to high-performance fighter jets to space travelling vessels. One of the concerns of any flight surgeon is high-altitude DCS. This form of DCS differs in many ways from the traditional form of DCS in presentation, consequences, and treatment options available. This plenary presentation will provide an exploratory introduction to the topic of high-altitude DCS and a discussion of the challenges a flight surgeon faces with respect to its prevention and management.

About Dr. Harrison:

Dr. Harrison is the Senior Associate Consultant, Departments of Emergency Medicine and Critical Care Medicine, Mayo Clinic, Jacksonville, Florida.  Dr. Harrison completed his undergraduate and graduate studies in exercise physiology at the University of New Brunswick, Fredericton NB. He completed a doctorate in exercise physiology and advanced statistical analysis at the University of Regina, Regina, Saskatchewan, prior to medical school. While attending Saba University School of Medicine, Saba, Netherlands Antilles he earned a master’s degree in hyperbaric medicine concurrent to his MD. He served as a chief resident at Henry Ford Hospital in Detroit, Michigan, while completing a combined emergency medicine / internal medicine / critical care medicine training program. Dr Harrison obtained a master’s in public health from the University of Minnesota and completed his fellowship training in aerospace medicine at Mayo Clinic in Rochester, Minnesota, in July 2018. He is faculty at Mayo Clinic in Jacksonville, Florida, in the departments of emergency medicine and critical care medicine. His research interests include spaceflight, military aviation, decompression sickness, and high-altitude physiology. He is a three-time Ironman finisher; nitrox-certified rescue diver; an instrument rated private pilot; and the CEO of Lightyear Medical PLLC, a company providing contracted flight surgeon services to the commercial space industry.


Plenary: Decompression Modeling Panel

Speakers: Gregory Murphy, PhD; Dave Doolette, PhD; Laurens Howle, PhD
Time: 8:55 am - 9:50 am

About the lecture:
Reduction in ambient pressure can results in tissue gas supersaturation and bubble formation, which in turn may result in decompression sickness (DCS). Models of these processes underlie decompression schedules used to minimize the probability of DCS (PDCS). The most venerable model of DCS was proposed by Bucquoy (1861) who drew the parallel with bubble formation in an uncorked carbonated beverage. Haldane and colleagues (1908) established the common model structure in which gas supersaturation is modelled in a collection of compartments that represent different rates of gas uptake and washout in the body. Weathersby et al (1984, 1992) revolutionized how PDCS is quantified when they applied survival analysis and likelihood maximization to the use of gas and bubble dynamics to predict the occurrence of decompression sickness. Development of these probabilistic DCS models requires a large set of dive trial data which includes the pressure-time history of the dives with breathing gas information and DCS outcome information. Although there has been recent development on modeling venous gas emboli (VGE) the two primary categories of probabilistic DCS models are gas supersaturation and bubble dynamic models. Gas supersaturation models assign a risk to hypothetical tissue compartments in proportion to gas supersaturation above some level. Bubble dynamic models assign risk to the growth of hypothetical gas bubbles. Either type of model requires determination of some number of fitted parameters. Typically, model fitting is accomplished through log likelihood maximization but other methods such as Bayes inference may be used. Once optimized, the probabilistic models are typically tested against extrapolation data (data not included in the training data set). Optimized and tested models may then be used to estimate PDCS of decompression schedules or generate new decompression schedules at a target PDCS.

Gregory Murphy, PhD
Dr. F. Gregory Murphy has both a bachelor’s and master’s degree in computer science from Michigan Technological University and a Ph.D. from the department of Mechanical Engineering and Material Science at Duke University. His research interests are focused the development of gas supersaturation and bubble dynamics models to predict the onset and incidence of decompression sickness in humans. Other work includes the development of dive procedures and searching for solutions to computational problems related to the implementation of real time probabilistic algorithms predicting the risk of decompression sickness. Dr. Murphy is currently employed at the Navy Experimental Diving Unit as a research biomedical engineer studying decompression sickness. Outside of research Dr. Murphy remains active in the civilian diving community as a dive instructor for PADI, SDI, and TDI. He is also an avid cave diver which is what originally precipitated his move from Michigan to the panhandle of Florida.

David DooletteDavid Doolette, PhD
Assoc. Prof. David Doolette is a research scientist specializing in undersea medicine and physiology. His principal expertise is the development and testing of decompression. Other areas of expertise are diving and life support systems, diving procedures, and diving safety. He has published widely in the scientific and military technical literature. He has conducted basic academic research ranging from cellular to integrated system physiology. He has conducted applied research, providing solutions for recreational technical diving, commercial diving, and military diving communities. He has been diving since 1979 and is an avid underwater cave explorer. He has been a member of the Undersea Hyperbaric Medical Society since 1987.

HowleLaurnes Howle, PhD
Lars Howle is an Associate Professor of Mechanical Engineering and Materials Science at Duke University.

Professor Howle's research interests span the disciplines of thermal science, fluid dynamics, and nonlinear dynamics. His present research projects - visualization of convective fluid patterns, stabilization of the no-motion state in free convection and bifurcation in imperfect or distributed parameter systems - are split evenly between experimental and computational methods.

A key problem facing researchers studying convection in fluid-saturated porous media is the lack of a general, non-invasive method for pattern visualization and wave number measurement. Professor Howle designed innovative porous media which allow optical techniques to be used for the first time as a pattern visualization tool in the study of porous media convection.

Computational spectral methods are efficient methods of simulation of small aspect ratio convection systems. For large problems, these methods can become too expensive to be practical. Professor Howle developed a reduced Galerkin method which decreases the execution time by orders of magnitude for large problems. This extends the range of problems for which certain spectral methods may be used. He is currently studying porous free convection in systems with distributed properties and binary convection using the reduced Galerkin method.

Session D - Diving Medicine

Plenary: Assessing aftereffects of COVID related to Diving Medicine Panel

Speakers: Peter Lindholm, MD, PhD; Charlotte Sadler, MD; Tony Alleman, MD; CDR Joy Dierks
Time: 1:00 pm - 1:55 pm

About the Lecture:
Integration of challenges in fitness to dive over commercial, recreational and military divers. Imaging considerations in presented cases. Panel moderation. The aim of this lecture is to discuss the challenges of divers returning to dive after having recovered from COVID 19. This will be a panel discussion with representatives from the recreational, scientific, commercial, and military communities. Panelists will discuss their unique challenges encountered with their divers during the pandemic and will each present cases to be discussed. This will be followed by an audience Q&A with the panelists.

Lindholm photo for onlinePeter Lindholm, MD, PhD
Dr. Lindholm is Professor in Residence, Gurnee Endowed Chair of Hyperbaric and Diving Medicine Research, Department of Emergency Medicine, University of California San Diego. He is a radiologist (licensed in Sweden), and associate professor in physiology and radiology from the Karolinska Institutet in Sweden. Together with colleagues at UCSD he developed the widespread guidelines for clinicians in evaluation of divers post-covid: Sadler C, Alvarez Villela M, Van Hoesen K, Grover I, Lang M, Neuman T, Lindholm P. Diving after COVID-19: Fitness to dive assessment and medical guidance. Diving Hyperbaric Medicine 2020 2020 Sep 30;50(3):278-287. doi: 10.28920/dhm50.3.278-287. PMID: 32957131.



sadler headshot 2Charlotte Sadler, MD
Charlotte Sadler is currently an Assistant Professor of Emergency Medicine and Hyperbaric Medicine at University of California, San Diego. She is also the program director of the Undersea and Hyperbaric Medicine fellowship at UCSD. She graduated medical school in her home state of Iowa at the Carver College of Medicine, University of Iowa. She completed her residency in Emergency Medicine and fellowship in Hyperbaric Medicine at UCSD. She currently serves on the UHMS board of directors and is co-chair of the UHMS Diving Committee. Her research interests include diving fatalities, cardiovascular disease and diving, rebreathers, and COVID-19 in divers. She helps run the diving medicine clinic at UCSD and was lead author of the UCSD Guidelines for returning to dive after COVID -19.

Dr. Alleman TNTony Alleman, MD
Dr. Alleman is a Louisiana native who joined Regional One Health in TN to treat patients in the hyperbaric oxygen therapy facility in our Wound Care Center.
Dr. Alleman earned his medical degree and completed his residency as co-chief resident in family practice at Louisiana State University Medical School in Shreveport. He is board-certified in family practice, occupational medicine and undersea and hyperbaric medicine.
Dr. Alleman completed two fellowships: one in hyperbaric medicine at LSU, New Orleans and one in occupational medicine at Duke University Medical Center in Durham, North Carolina.
He became interested in hyperbaric medicine while working as an occupational medicine physician in Lafayette, Louisiana. After Hurricane Katrina he recruited a physician from New Orleans who treated commercial divers. To further his own knowledge, Dr. Alleman completed his hyperbaric fellowship and earned board certification in undersea and hyperbaric medicine.
“It’s a wonderful treatment for a very diverse group of conditions,” Dr. Alleman said of hyperbaric medicine. “In many cases it offers a patient their best or only chance at recovery.”
Dr. Alleman was chairman of the Undersea and Hyperbaric Medical Society committee that published the UHMS Medical Fitness to Work Guidelines for Multiplace Inside Attendants 1st edition. He is chairman of the Association of Diving Contractors Physician’s Diving Advisory Committee and has been on the faculty of the UHMS fitness to dive course for six years.

DierksCDR Joy Dierks, MD, MPH, MSTI

About CDR Dierks:

CDR Joy Dierks was commissioned in 2000 and selected to attend the Uniformed Services University of the Health Sciences School of Medicine in Bethesda Maryland. She graduated in 2004 with her Doctorate of Medicine and completed a transitional internship at Portsmouth Naval Hospital in Norfolk, VA in 2005.

Following internship CDR Dierks was selected for the Diving Medical Officer program. She completed school at Naval Diving and Salvage Training Center, Panama City, FL and Undersea Medicine at the Naval Undersea Medical Institute, Groton, CT. Upon graduation she received Surgeons General’s award for the outstanding graduate.

Her first assignment was as the Diving and Undersea Medical Officer, assigned to the USS Emory S. Land (AS-39) home ported in La Maddalena, Italy.  During this assignment she completed a deployment to the Gulf of Guinea and executed the base closure/change of homeport to Naval Base Kitsap in Bremerton, WA.  The base closure involved one of the largest salvage operations in naval history, CDR Dierks served as Medical Support Supervisor for this operation, providing medical treatment and care coordination for visiting naval and civilian divers in addition to participating in the clean up working as a salvage diver. During this tour she earned her surface warfare device.

In April 2008, CDR Dierks reported to Explosive Ordnance Disposal (EOD) Group ONE to serve as Senior Medical Officer/ Force Surgeon. Her responsibilities included medical oversight of seven subordinate EOD Mobile Units and Mobile Diving Salvage Unit ONE with several thousand sailors scattered throughout the Pacific.  During her tenure she over saw the creation of the new Expeditionary Support Unit ONE Medical department, standardized of medical training for EOD operators at Training and Evaluation Unit ONE, Hanta virus control/abatement at Darwin Wash training area on Naval Weapons Station China Lake. She jointly presented her Hanta virus work with NEPMU-5 at the Navy Marine Corps Public Health Conference.

In June 2013 CDR Dierks completed Preventive Medicine residency and earned a Master’s in Public Health from Johns Hopkins University School of Public Health in Baltimore, MD. In addition, she completed the Public Health Emergency Officer (PHEO) course and served as the resident representative on the Johns Hopkins Residency Advisory Council.

Following residency, CDR Dierks reported as the Preventive Medicine Officer to III Marine Expeditionary Force (III MEF) in Okinawa, Japan. Additionally, she served as the acting III MEF Surgeon (May 2014- August 2014). Subsequently as Deputy III MEF surgeon and 3rd Marine Expeditionary Battalion (3rd MEB) Surgeon for the remainder of her tour. She was responsible for health care and force health protection for approximately 27,000 Marines and Sailors operating throughout the Pacific. CDR Dierks served as the JTF-505 forward surgeon for Operation Sahayogi Haat, the 2015 Nepal Earthquake response. She was instrumental in the identification and repatriation of the US Marines, Nepalese civilians and army personnel involved in a helicopter crash.  In addition she spearheaded several initiatives at III MEF to improve force health protection through a quality improvement project targeting increased reporting of heat casualties and quantifying contributing human factors. She facilitated new provider orientation for III MEF medical providers and collaborated with Naval Hospital Okinawa to develop monthly grand rounds for all Okinawa military medical providers. CDR Dierks led the investigation of largest leptospirosis outbreak in US military history coordinating with both military and local Japanese health officials. She was the lead author on a publication detailing this outbreak and the lessons learned. Finally, CDR Dierks earned board certification in Preventive Medicine, Occupation and Environmental Medicine, completed USMC Command and Staff (JPME-1) and earned the Fleet Marine Force (FMF) warfare device.

From August 2015 – August 2018 CDR Dierks served as the Personnel Reliability Program (PRP) Competent Medical Authority (CMA) Community Manager at the Bureau of Medicine and Surgery (BUMED). She was the first full-time person to hold this position and brought Navy Medicine support to the nuclear weapons community to the next level. In this role she oversaw medical support to the Navy Nuclear Deterrence Mission directly serving as the Surgeon General’s liaison to Strategic Systems Programs. She was only the second Navy medically trained person to serve as a Nuclear Weapons Technical Inspector/subject matter expert to Strategic Systems Program (SSP). Additionally she worked with the Head of Undersea Medicine (UM) to increase medical student recruitment and mentorship for Undersea Medicine Programs. In this roles, she oversaw the preparation of UM packages for the Graduate Medical Education Selection Board resulting in the highest undersea medical officer candidate recruitment in the past 10 years. She completed the requirements for her submarine medical officer warfare device. Finally, she graduated in July 2018 with a Masters in Science and Technology Intelligence from National Intelligence University with a concentration is Weapons of Mass Destruction.

In August of 2018 CDR Dierks reported to Naval Hospital Yokosuka Japan. She served as Director, Branch Health Clinics and Preventive Medicine/ Occupational Medicine/ Undersea Medicine Staff Physician. CDR Dierks was responsible for six branch health clinics in two countries and one territory with over 600 personnel and a budget in excess of $ 11 million dollars and travel funds in excess of $400 thousand dollars. Additionally, she served as the Public Health Emergency Officer and Preventive Medicine consultant to Seventh Fleet. For the April-May 2019 American College of Occupational Medicine Conference, CDR Dierks gave two presentations- “Bio-security and Gene editing technologies” and “The Navy’s response to climate change.” She served as the co-champion for telehealth initiatives at the command.

In March of 2020 CDR Dierks returned to BUMED and served as acting Head, Undersea Medicine and Radiation Health from April 2020 – August 2020. During this time she led the Undersea Medicine clinical community that produced return to diving guidance for U.S. Navy diving personnel. In her current position she serves as deputy, for waivers and standards, and is the senior medical reviewer for all special duty (submarine, diving, nuclear field duty, and special warfare) waivers for all Navy and Marine Corps personnel, U.S. Coast Guard, and Department of the Navy (DoN) civilians. She assists with case reviews for the radiation effects advisory board (REAB) for DoN civilians and active duty members in the radiation health program.  Additionally, she current leads the effort to revise the Manual of the Medical Department chapter 15 sections on special duty.  She maintains her clinical currency through regular clinic hours at Fort Belvoir Community Hospital serving as Occupational and Diving Medicine Physican.

CDR Dierks’ personnel awards include the Meritorious Service Medal with two gold stars, the Joint Commendation Medal, Humanitarian Service Medal and the Navy Commendation Medal with gold star. She holds the following warfare devices: Submarine Medical Officer device, Surface Warfare Medical Officer device, and Fleet Marine Force. She holds an active TS-SCI clearance.

Plenary: International perspectives in DCS Management: Controversies in treatment tables. Series of cases and how they would use the tables Panel

Speakers: Richard Moon, MD; Cuauhteomoc Sanchez, MD; Simon Mitchell, MD; Maria-Teresa David, DO
Time: 2:35 pm - 3:30 pm

MOONRichard Moon, MD
Professor of Anesthesiology Medical Director, Hyperbaric Center, Professor of Medicine.
Research interests include the study of cardiorespiratory function in humans exposed to environmental conditions ranging from 200 feet of seawater depth to high altitude, gas exchange during diving, the pathophysiology of high-altitude pulmonary edema, the effect of anesthesia and postoperative analgesia on pulmonary function and monitoring of tissue oxygenation. Ongoing human studies include mechanisms of immersion pulmonary edema and the effect of chemosensitivity on postoperative ventilation and gas exchange.

Cuauhtoemoc Sanchez, MD

Sanchez"Management of DCS in sea harvesters using monoplace chambers with no air brakes."
Decompression illness is normally managed using a US Navy TT6 in a multiplace chamber. The present development of HBO units is with monoplace chambers and many physicians and divers hesitate to use them to treat DCI cases. Sea harvesters around the world, dive extreme profiles and have a large inert gas overload. We present our experience of 500 cases of DCI in sea harvesters, managed with a monoplace chamber with no air brakes. Our results are comparable with those obtained using multiplace chambers with a USN TT6.

About Dr. Sanchez:
E. Cuauhtémoc Sánchez-Rodríguez graduated from the School of Medicine of the National Autonomous University of Mexico (UNAM). He is a Diver Medical Officer NOAA, IADC, and EDTC. He did a 3-year fellowship at the Adam´s Cowley Shock Trauma Center at the University of Maryland. He has a master’s in Medical Sciences, Public Health, Auditing Health Systems, Administration of Hospitals, and is a Master of the APWCA. He co-founded DAN Latin America and is the Director of DAN Mexico and the Caribbean. He is a Professor on Diving and Hyperbaric Medicine at UNAM and an Associate Clinical Professor at MSU. He is a founder of the Mexican Undersea and Hyperbaric Medical Society and of the Mexican Wound Healing Society. He is a past Vice-President of the UHMS, and a Fellow and a member of the Executive Committee of the ACHM. He is the Director of the Wound Care, Undersea and Hyperbaric Medicine Units at O´Horan and CEM Hospitals, in Yucatán, Mexico. 

mitchellSimon Mitchell, MB ChB, PhD
Professor Simon Mitchell, MB ChB, PhD, DipAdvDHM (ANZCA), DipOccMed, FUHM, FANZCA. Professor of Anaesthesiology, School of Medicine, University of Auckland.
Simon is a physician and scientist with specialist training in diving medicine and anaesthesiology. He is widely published with over 150 papers or book chapters. He co-authored the 5th edition of “Diving and Subaquatic Medicine” and has two chapters on decompression illness in the most recent edition of Bennett and Elliott. He has twice been Vice President of the Undersea and Hyperbaric Medicine Society (USA) and in 2010 received the society’s Behnke Award for contributions to the science of diving and hyperbaric medicine. In the past Simon was a naval diving medical officer and medical director of the Wesley Centre for Hyperbaric Medicine in Brisbane. He now works as a consultant anaesthetist at Auckland City Hospital, and Professor in Anaesthesiology at the University of Auckland. He provides on-call cover for diving and hyperbaric emergencies at the North Shore Hospital Hyperbaric Unit in Auckland.
Simon assumed the role of Editor of Diving and Hyperbaric Medicine in January 2019.
Simon’s diving career has included more than 6000 dives spanning sport, scientific, commercial, and military diving. He has been a lead member of teams that were the first to dive and identify three deep wrecks of high historical significance in Australia and New Zealand. At the time of one of these dives (2002) the 180 m depth represented the deepest wreck dive ever undertaken. He was elected to Fellowship of the Explorers’ Club of New York in 2006, and was the DAN Rolex Diver of the Year in 2015.

MTDavid ec19daeaMaria-Teresa David, DO
“Hawaiian Experience and the Deep Tables”
Dr. David will discuss the unique diving population in Hawaii; the utilization and development of UH unique deep dive tables and Hawaii's unique diving population , deep tables, and challenges in treatment.

About Dr. David:
Dr. David has been a faculty member for 21 years with University of Hawaii School of Medicine Hyperbaric Treatment Center -1997-2018 ; Board Certified in Internal Medicine and Undersea and Hyperbaric Medicine; now lives between Maui and St. Augustine Florida.