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Tech Sisterhood Under Pressure

Historically tech diving has been largely male-dominated, but all you have to do is look around to see that things are changing. For the better! Accordingly we thought it time to examine some of the issues unique to our tech diving sisterhood. Here Florida-based, interventional cardiologist and rebreather instructor Douglas Ebersole MD discusses a number of matters ranging from the risk of decompression illness (DCI) in women versus men, changes in risk due to menstrual cycles, contraceptives, the implications of pregnancy on diving and even cosmetic and reconstructive surgery.

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By Douglas Ebersole, MD
Header photo by Becky Kagan Schott, Selfie with Jitka Hanakova.

Historically, technical diving has been a male-dominated sport; however, that is changing. In fact, at this year’s Bonaire Tek event in October, there were 24 women in attendance, representing almost 30% of the attendees. Little attention has been paid to issues unique to women in technical diving. This article will address a number of these. Specifically, it will discuss the risk of decompression illness (DCI) in women versus men, changes in risk of DCI at various times during the menstrual cycle as well as the effects of oral contraceptives, pregnancy, cosmetic and reconstructive surgery, menopause, and cardiovascular health.

In an attempt to show full transparency, I am NOT a woman, and I fully understand that immediately puts my credibility into question. However, I have lots of family and friends who are women technical divers, and I reached out to them for help deciding on topics to approach. Thanks to my wife, who is a rebreather diver; our daughter, who is a rebreather instructor; Jill Heinreth, Becky Schott, Mel Clark, Jo Mikutowicz, and Rosemary “Roz” Lunn for their input.  I also heavily referenced a textbook by Caroline Fife, M.D. entitled Women Under Pressure.

Decompression Illness and Gender

When looking at women and the risk of decompression illness, three factors bear consideration. First, do women and men differ in their risk for decompression sickness when under the same decompression stress? Second, what (if any) effect does a woman’s menstrual cycle have on her risk for decompression sickness? And, finally, what is the data on decompression sickness risk while on oral contraceptives?

The data we have on DCI risk based on gender is retrospective and inconclusive. In a paper in Undersea Biomedical Research in 1987, Zwingelberg looked retrospectively at Navy divers, 28 women and 487 men, with a combined 878 training dives with equal representations of exposures. In this study there was no difference in risk of DCI by gender.

In 1992, in Undersea Biomedical Research, Robertson retrospectively looked at 111 cases of DCI in Australia. In this report, women had a 4.3 times greater incidence in Type II decompression sickness compared to men.

In 1993, Vann reported on this issue using the Divers Alert Network (DAN) flying after diving data and published in Aviation Space and Environmental Medicine. His data also suggested that women had a higher risk of Type II decompression illness compared to men and had more residual symptoms. However, he mentioned that it was unclear if the incidence was truly higher or if there was reporting bias.

Mother and daughter doing a check.
Photo by Andrea Petersen.

In another study in Aviation Space and Environmental Medicine in 2002, St. Leger Dowse sent questionnaires to divers (53% men and 47% women). This data suggested that before controlling for diving patterns, women had a 1.67 time greater risk of DCI. However, after controlling for diving patterns, men actually had a 2.57 time greater risk of DCI.

Finally, Hagberg reported in Undersea and Hyperbaric Medicine in 2003 on 1,516 male and 226 female diving instructors and dive masters who self-reported their incidence of DCI. This data set contained thousands of dives of various types and showed a risk of DCI for men of 1.52 per 1,000 dives and a risk of DCI for women of 1.27 per 1,000 dives.

In conclusion, the differences in dive profiles in the available observational data make it impossible to draw firm conclusions regarding the effect of gender on DCI among scuba divers.

Decompression Illness and the Menstrual Cycle

A woman’s menstrual cycle is typically 28 days and is controlled by the interactions and levels among three hormones: estrogen, progesterone, and testosterone. Several retrospective studies have tried to correlate the risk of decompression illness at various times during the menstrual cycle. In 1998, Lee et al, reviewed 73 records and found 35% of DCI events occurred within the first five days of the menstrual cycle. 

A group of women technical divers. Photo courtesy of Roz Lunn.

In 2006, St. Leger Dowse reviewed more than 50,000 dives and 11,000 menstrual cycles in 570 women. This showed the highest incidence of diving problems was in the first week of a 28-day cycle while the lowest risk was in week three. She then also reported in 2006 the results of 250 prospective DCI records and found the highest incidence of DCI was in the first week while the lowest incidence was in the third week of a 28-day cycle.

While the data above for menstruating women suggests a higher risk of DCI in the first week of their cycle, the data for women on birth control pills is less clear. These women have a pharmaceutically driven menstrual cycle.  While studies have assumed a 28-day cycle in these women, St. Leger Dowse in the Journal of Obstetrics and Gynecology in 2007 reported that only 42% of women on oral birth control pills had a 28-day cycle. The remainder ranged from 21 to 60 days. As a result, the data on DCI in women on birth control pills is clouded, inconclusive, and confusing.  

In conclusion, the mechanism of risk across the menstrual cycle is not known, but hormonal fluctuations may be a possible factor. And one final note – while menstruation may decrease exercise tolerance due to anemia and volume depletion, it does NOT increase the likelihood of shark attack.  

Cari Baun and Jennifer Mayfield having fun underwater. Courtesy of Jennifer Mayfield.

Pregnancy and Diving

Human data on the effects of hyperbaric oxygen on the fetus are limited. In 1980, Bolton reported in Biomedical Research on 109 women who dived before and during pregnancy compared to 69 women who dived before pregnancy but stopped diving once pregnancy was diagnosed. Babies born to  women who dived during pregnancy had lower birth weights, more respiratory difficulty, and birth defects, including hemivertebrae, absence of a hand, a ventricular septal defect, coarctation of the aorta, and pyloric stenosis. It should be noted that there were no birth defects in the babies born to women who stopped diving when they learned they were pregnant. 

Once again, St. Leger Dowse chimed in on this issue. She reported in Obstetrics and Gynecology in 2006 on retrospective data from 1990-1992 and prospective data from 1996-2000 on 129 women who continued to dive, either purposely or inadvertently, during their pregnancy. This involved 1,465 dives during 157 pregnancies. Of note, while only 65% of women stopped diving during the first trimester of their pregnancy in 1990-1992, by 1996-2000 this number increased to 90%. For the total population, the incidence of spontaneous abortion was 14% and the serious birth defect rate was 2.7%, which is similar to the rate in nondivers.

Photo by Meredith Tanguay.

Of course, if DCI occurs in a pregnant woman, the fetus also becomes a patient. Because of fetal blood flow, venous bubbles in the mother will be arterialized into the systemic circulation of the fetus through the foramen ovale, which could be devastating. Of note, there is no data on fetal injury related to maternal hyperbaric therapy. 

There are other issues with diving during pregnancy not related to decompression stress. Pregnancy increases total body water and swelling of mucous membranes, making equalization difficult. Two-thirds of women have nausea and vomiting, or “morning sickness,” in early pregnancy. Additionally, gastric reflux (heartburn) is very common during pregnancy and is already common with immersion for any diver.

After vaginal delivery, women should refrain from diving for 21 days postpartum to allow time for the cervix to close so as to lessen the risk of ascending infection. After cesarean delivery, most obstetricians recommend refraining from diving for 4-6 weeks.

The issue for diving during breastfeeding is the risk of marine bacteria colonizing on the skin, resulting in mastitis in the mother and bacterial diarrhea in the infant.

Diving and Breast Augmentation

In the early 1980s, Divers Alert Network began receiving calls about the concern of dissolved gas expanding on a commercial flight home putting stress on the seams of breast implants. In 1988, Vann reported in Plastic and Reconstructive Surgery on the results of hyperbaric followed by hypobaric conditions on a variety of saline and silicone implants. Depths were as deep as 120 ft/37 m and dives times of up to 72 hours. Then, after a 21-hour surface interval, the implants were taken to 7000 ft/2.1 km for two hours and then to 30,000 ft/9.1 km for two hours to simulate loss of cabin pressure. The implant volume increased 1.0-4.0% at the surface, 0.0-5.0% at 7000 ft/2.1 km, and 4.0-12.0% at 30,000 ft/9.1 km. Saline implants were less affected than silicone implants, all bubbles resolved over time, and the volume change was not enough to risk rupture.

Renata on Hoki mast. Photo by Becky Kagan Schott.

Post operatively after breast augmentation, women should wait 4-6 weeks before returning to diving and avoid putting tight shoulder straps over the implants to avoid undue pressure.  Finally, while saline implants are neutrally buoyant, silicone implants are negatively buoyant.

Diving, Smoking, and Oral Contraception

Fourteen percent of women age 14-44 use oral contraceptives. These birth control pills have been shown to increase the risk for forming blood clots resulting in stroke, heart attack, deep venous thrombosis (blood clots in the legs), and pulmonary emboli (blood clots in the lungs) in women who smoke. While nonsmoking women on birth control pills who are less than 35 years of age have no increase in risk compared to nonsmoking women not on birth control pills, women who smoke have a significant increase in the risk for these conditions.

Compared to nonsmokers who are not on birth control pills, women who smoke less than one pack per day while on birth control pills have a three-fold increased risk of these conditions, while smokers of more than one pack per day have a 23-fold increased risk. 

Diving and Menopause

Rebreather selfie by Jill Heinerth.

Twenty-two percent of women divers making more than eight dives per year are 55 years of age or older. During menopause, women are at a much higher risk for osteoporosis than men due to a baseline lower bone density, followed by the loss of estrogen which accelerates the rate of bone demineralization. The average age for menopause is 50 years, and bone loss increases dramatically after this. Significant bone loss will be seen at 60-70 years and fractures begin occurring at 70-75 years. Thankfully, there are now treatments to blunt this bone loss. Women with significant osteoporosis of the spine should be cautious about walking while wearing scuba cylinders due to an increased risk of vertebral crush fractures.

Cardiovascular Disease and Menopause

The leading cause of death in women is cardiovascular disease. In addition, approximately 100 U.S. and Canadian divers, both women and men, die while scuba diving each year. Twenty-five percent of those over age 35 have a cardiac cause. While the risk for cardiovascular death is quite low in premenopausal women, after menopause, the risk for women quickly becomes comparable to that of men. As a result, all women, like their male counterparts, should be vigilant in controlling the risk factors for cardiovascular disease, emphasizing blood pressure and cholesterol control, screening for and treating diabetes, and avoiding smoking in addition to exercise and weight control.

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Conclusions

  • Women are at increased risk for decompression illness during the first week of their menses.
  • The risk of decompression illness for a woman on oral contraceptives is unclear.
  • A woman diver should stop diving as soon as she knows or suspects that she is pregnant.
  • Breast implants can swell when going from hyperbaric (diving) to hypobaric (air travel) environments, but not enough to risk rupture.
  • Women, especially those on oral contraceptives, are at a much greater health risk if they smoke.
  • Osteoporosis with aging can put women at risk for spinal compression fractures.
  • Cardiovascular health is as important a concern for women as it is for men.
 Nathalie Lasselin with her big camera. Courtesy Nathalie Lasselin.

Dive Deeper:

Dive Risk Factors, Gas Bubble Formation, and Decompression Illness in Recreational SCUBA Diving: Analysis of DAN Europe DSL Data Base


Douglas Ebersole, MD, is an interventional cardiologist at Watson Clinic in Lakeland, Florida, and the Director of the Structural Heart Program at Lakeland Regional Health. He is also an avid technical diver, cave diver, and CCR trimix instructor, as well as cardiology consultant to Divers Alert Network (DAN).

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The Top Stories of 2022

We kick off the New Year with 10 hand-curated stories from our growing sea of content. They represent some of the most read, important, and fun stories from the last year. We hope you will enjoy them!

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Header image by InDEPTH art director SJ Alice Bennett. Two Dirty Dozen rebreather divers exploring a sunken armored tank at Chuuk Lagoon.

Greetings tekkies and mission-oriented divers,

January marks our fourth full year publishing InDEPTH, and it has arguably been our best year yet for content. In 2022, we published 113 new stories, and conducted seven surveys with our partner, The Business of Diving Institute—yes, it’s all about the data!

Rebreathers, of course, were the hot topic in 2022, particularly as helium prices continued to rise and availability was limited in some areas. In response, we offered a variety of stories on rebreather diving including in-depth looks at various units.

This burgeoning interest in rebreathers comes at a time when diving professionals from around the world will be headed to Malta this coming April for an industry, governmental and scientific symposium called Rebreather Forum 4. If you are professionally involved in rebreather diving, we encourage you to attend. 

I would like to thank our readers and subscribers, for your continuing interest and support. We want to be your number one, go-to source for serious diving content, and we will continue to work hard to win your loyalty! I also want to thank our many contributors from the global tech community, whose work and labors of love are represented here and elsewhere in InDEPTH. Thank you for your contributions! Special shout to our phenomenal, go-to picture makers and writers Jason Brown, Stratis Kas and Fan Ping! Keep your eyes on them people!

Lastly, I want to thank our illustrious sponsors, who make InDEPTH possible! Please join me in giving a big shout out to; Azoth Systems, Buddy Dive Resort, DAN Europe, Dirty Dozen Expeditions, Dive Rite, Divesoft, Extreme Exposure, Fathom Systems, Fourth Element, Halcyon Dive Systems, O’Three, OZTek, Shearwater Research, and The Human Diver. Thank you!! We hope that you will support these depth full diving brands!

In what has now become a tradition, we kick off the New Year with 10 hand-curated stories from our growing sea of content in The Top Stories of 2022. They represent some of the most read, important, intriguing and fun stories from the last year. We hope you will enjoy them!

We would appreciate it, if you would take a few minutes to complete our annual Reader’s Survey. This will help us deliver better content to your inbox. Our thanks in advance for your help!

 We have some exciting stories planned for 2023, so stay tuned!

Safe diving,
Michael Menduno/M2
Editor-in-chief

Here are the results of our 2022 surveys that we conducted with the Business of Diving Institute: InDEPTH’s 2022 Surveys .

There’s also a FREE DOWNLOAD of aquaCORPS #6 COMPUTING for you at the bottom of the page!


Divers Helping Divers: Next Stop Ukraine

June 1, 2022


1. Will Open Circuit Go the Way of the Dinosaur?

Closed circuit rebreathers have arguably become the platform of choice for BIG DIVES. So, does it make any sense to continue to train divers to conduct deep, open circuit mix dives? Here physiologist Neal Pollock examines both platforms from an operational and physiological perspective. The results? Deep open circuit dives may well be destined to share the fate of the Spinosaurus. Here’s why.

And if you’re wondering exactly, how many “deep” open circuit dives you’d have to conduct—you are using helium aren’t you?—to pay for a rebreather, training, and necessary experience dives, you’re in luck! Rebreather instructor and tech Instructor trainer Guy Shockey does the math in: The Economics of Choosing CCR Vs OC

Want a deeper understanding of how your rebreather’s scrubber works? Get a copy of John Clarke’s geeky new monograph, “Breakthrough: Revealing the Secrets of Rebreather Scrubber Canisters..” Dr. Clarke was the scientific director of the US Navy Experimental Diving Unit (NEDU) for 27 years.

Helium Technical Diving

2. The Price of Helium is Up in the Air

With helium prices on the rise, and limited or no availability in some regions, we decided to conduct a survey of global GUE instructors and dive centers to get a reading on their pain thresholds. We feel your pain—especially you OC divers! InDEPTH editor Ashley Stewart then reached out to the gas industry’s go-to helium market expert Phil Kornbluth for a prognosis. Here’s what we found out.

3. The Diving Industry Is Run By Middle Aged White Blokes. Our Future Depends on Making Them Uncomfortable.

Ahead of Women’s Dive Day, July 16, 2022 UK instructor and course director Alex Griffin examines why the industry appears to have trouble attracting and retaining divers from diverse backgrounds—and what we all can do about it. It might make you uncomfortable.

4. How Deep is Your Library?

Technical diving requires a deep body of knowledge that must be kept current. So, it seemed appropriate to ask, what books should tekkies have on their shelves? To answer that question, we turned to DAN’s nerdy risk mitigation coordinator cum cave diver, Christine Tamburri to suss out suitable tekkie tomes. Here is what she uncovered. Feed your head!

5. The Challenge for the Technical Diving Community? Connecting Divers With the Environment

While tech diving has come a long way in terms of extending our underwater envelope, enabling tech divers to truly go where no one has gone before, environmental consultant and educator, Alex Brylske, Ph.D argues that as a community there is still room for significant improvement in connecting divers with the environment. In the process, he details the results and meaning of InDEPTH’s survey of Sustainability in the Scuba Diving Industry and offers suggestions for moving forward.

6. Celebrating Wes Skiles

We explore and celebrate the extraordinary life and work of cave diving pioneer, explorer, conservationist, and underwater cinematographer/ photographer Wesley C. Skiles with a collection of curated interviews, portraits and perspectives from Fred Garth and Bret Gilliam, Julia Hauserman, Jill Heinerth, Todd Kincaid, Emory Kristof, and Bill Stone. We also feature nine essential Skiles films, some of his National Geographic photos, and a bevy of articles and content from the National Speleological Society-Cave Diving Section (NSS-CDS).

7. The First Helium-based Mix Dives Conducted by Pre-Tech Explorers (1967-1988)

More than 20 years before the emergence of technical diving, a handful of intrepid cave divers who were perilously pushing the limits of air diving, began experimenting with helium mixes for deep diving. Some succeeded, several were injured, and one almost drowned. Though some of their tales are known, no one had produced a definitive chronology until Woodville Karst Plain Project (WKPP) board member and explorer Chris Werner set out to clarify the record. Here, for the first time, are the origins of the “mixed gas” aka “technical diving revolution” that irrevocably altered the course of sport diving.

8. When Easy Doesn’t Do It: Dual Rebreathers in Extended-Range Cave Diving

Rebreather technology has enabled cave explorers to extend their underwater envelope significantly deeper and longer. As a result, a number of teams are pushing beyond the practical limits of open circuit bailout and so have turned to bailout rebreathers. But not without challenges! Tech instructor and DAN Europe editor Tim Blömeke dives into the latest research and field experience and explains what’s happening.

 9. Can We Create A Safety Culture In Diving? Probably Not. Here’s Why.

How do we improve our safety culture in diving? Is it indeed something that we as a community of divers can affect? Human factors coach Gareth Lock argues that there is no magic bullet and, in fact, that the sports diving industry needs to make a fundamental shift in how it manages diver safety if we are to improve safety. In other words, we still have a ways to go. The retired British Royal Air Force officer explains why.

And without question, the MOST FUN story of 2022, err, it actually dropped DEC 2021—we had it in the can. Call it:

10. Shitwrecks

We teamed up with some potty-minded wreckers to explore the poop decks of shipwrecks around the world, giving a new twist to the term, “Water Sports.” We offer these heady bits.

Note that InDEPTH featured a number of new shipwreck, cave and mine exploration projects in 2022, see: InDEPTH’s EXPLORATION ARCHIVES

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Download some early tech history with a digital copy of aquaCORPS #6 COMPUTING (1993) sponsored by our friends at Shearwater Research!

“Yes! I shall design this computer for you. And I shall name it also unto you. And it shall be called … the Earth.” Douglas Adams, The Hitchhiker’s Guide to The Galaxy

aquaCORPS #6 COMPUTING was published in June 1993 following the magazine’s first technical diving conference, TEK.93, held in Orlando, Florida in January of that year. The issue focused on dive computing and included interviews with nitrox computer developers Randy Bohrer (Bridge), Kevin Gurr (ACE), Paul Heinmiller (Phoenix), an interview with Karl Huggins (EDGE), and a story about commercial decompression software developed by decompression engineer, JP Imbert. Note that there were no trimix diving computers at the time.

There was also a review by Dr. RW Bill Hamilton and John Crea, of four ten newly-released desktop mixed gas decompression programs. The cover of the issue shows a visualization of decompression risk that was rendered by David Story on a high-end Silicon Graphics workstation. The issue went on to envision the future of dive computing and provided a tekkie guide to the newly emerging Internet, and its implication for diving.

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