Hi everybody, welcome to scuba diver magazine, this is the first part of a new series that
focusses on water safety and learning points that we can take from analysing accidents
so that we can all learn from and improve our safety. This first video
looks at a study about snorkelling fatalities in Hawaii and potential causes and factors.
The state was recording an increasing number of snorkelling fatalities as years progress,
and they wanted to know why and how to stop it. Now that the study has
concluded we can take a closer look at the findings and improve our safety.
Snorkelling is essentially a safe pastime – but the conclusion of the final
report from Hawaii’s Snorkel Safety Study is that pulmonary oedema is a hidden danger
that can render that pastime lethal unless you notice a number of red flags and take action.
The study was prompted by the worrying number of snorkelling deaths that occur in the Pacific
island state. In the nine years up to 2021, 204 people are known to have died while snorkelling,
more than in any other water-based activity (by comparison, 25 died while scuba-diving and 49
freediving in the same period). All but 20 of those snorkellers were tourists, about 90%.
The Department of health was looking at this information and many of these fatalities occurred
in mild conditions and were not accompanied by the classic signs of distress. So far,
the cause has been attributed to the assumption that tourists are less likely to be good swimmers,
less likely have a lot of snorkelling experience, experience with Hawaiian waters or that they
suffered heart or other health conditions. That was until this study was proposed.
The Snorkel Safety Study has four components; the Snorkel Airways Resistance Analyser, or SARA,
that studied various snorkel designs on the market today and their breathing resistances using a
custom made analysing machine. Medical Examiners Office Reports examination on MEs findings
on these fatalities, going through autopsy reports and looking for similarities and trends.
A Case Study Investigation and a Snorkel Safety Survey for first-hand accounts from snorkellers
who had gotten into trouble while snorkelling and asking them details about their events and again,
looking for similarities. ROPE
In Hawaii many of the accounts reported an unresponsive snorkeler motionless,
close to shore, in calm conditions, sometimes soon after entering the water, and without signs
of distress. These are not the characteristics of classic Drowning by Aspiration, or inhaling water
first, that usually display active panic. The Snorkel Safety Study hypothesized that this quick
and silent pattern of drowning was consistent with pulmonary edema, where fluid from the body entered
the lungs first and that the snorkel itself may trigger and accelerate this pulmonary edema.
Instead of inhaling water due to struggle, it could be that the increase work that the
snorkeller had to inhale with to draw air through restrictions in the snorkel could
cause an increase in the vacuum inside their lungs or Negative Trans-thoracic Pressure.
This vacuum can draw your bodily fluid from your capillaries into your lungs. The lungs are now
less efficient that lead to reduced blood Oxygen levels, loss of motor strength and
mental confusion, which is calm and quiet. Now, we see pulmanory edema in a few circumstances
from different causes; in scuba diving it’s known as Immersion Pulmonary Edema or IPE, long distance
swimming has Swimming Induced Pulmonary Edema or SIPE, mountain climbing has High Altitude
Pulmonary Edema or HAPE and now from this study snorkelling has Snorkelling Induced Rapid Onset
Pulmonary Edema or ROPE for short. FINDINGS
The key findings of the study are that Hypoxia due to ROPE is the cause for some, if not most,
of the snorkel-related fatal and near fatal drownings. Snorkel Resistance and horizontal
immersion are predisposing factors that can contribute to the onset of ROPE.
Cardiac disease, in particular elevated Left Ventricle End Diastolic Pressure (LVEDP),
has been identified as a risk factor for ROPE. High airflow resistance to inhalation
adds to the risk of developing ROPE and across the snorkel and full face snorkels tested they found a
wide range of airflow resistances. One interesting finding was that full face snorkels masks posed no
inherent advantage or disadvantage compared to other snorkel designs in terms of resistance
to inhalation of air however, they did present additional challenges. Now, only four full face
snorkel designs were tested and I don’t believe they looked into carbon dioxide levels in their
tests, they only looked at breathing resistance. Recent prolonged air travel was also highlighted
as a potential concern as many snorkellers had recently spent a substantial amount of time
in air cabin conditions travelling to Hawaii. Cabin pressure is often equivalent to 8500 feet
above sea level and evidence shows that at these altitudes the permeability of the lungs mechanisms
naturally adjusts and leaves you more susceptible to pulmonary edema soon after longterm flights.
But, the study does stress that this is still a hypothesis and while it does have credible basis
in physiology and would neatly explain many of these drownings, studies are needed to define
long term flights as a risk factor. When studying snorkel designs,
while the researchers did find a wide range of resistance one factor that
appeared to have a large effect on the work of breathing was the presence of dry valves
with the most basic J snorkel having the lowest median results overall but, the design itself
would not guarantee a low work of breathing. And it was often internal choke points that you can’t
see from the outside that had the most effect. Results from all different designs varied with
some J snorkels with a higher resistance than full face snorkels and vice versa.
And, while full face snorkel masks tested did have a slightly higher median negative pressure
compared to other groups of snorkels the values weren’t significantly higher than separate snorkel
designs. However, in other areas of the study, evaluation of design and first-hand accounts the
study highlights adverse features to full face snorkels including that they cannot be removed
as easily in urgent situations, even if the design had quick releases. You can’t simply spit out the
mouthpiece on the surface for some fresh air. You can’t clear water from the snorkel with a quick
blast, you can’t dive under the surface with them safely and valve malfunction may lead to serious
aspiration consequences. If you’re inhaling when a wave closes the top valve it creates a vacuum
inside the snorkel that holds the valve closed and even with good airway control you need to remember
to exhale before you can continue to inhale. CONCLUSION
The Study states that the most important finding is the conformation that ROPE induced hypoxia is
a mechanism leading to some, possibly most, fatal and non-fatal snorkel-related drownings
and the presence of the snorkel exasperates that. Heart Disease, especially elevated Left Ventricle
End Diastolic Pressure, is a likely risk factor that can lead to ROPE so,
if you have been diagnosed then it’s best to stay out of the water I’m afraid.
Snorkel design is important in reducing chances of ROPE however basic design itself
is not a guarantee of reduced resistance so try to invest in the best snorkel design with minimal
breathing resistance to reduce chances of ROPE. Snorkelling very shortly after a long flight MIGHT
increase your chances of ROPE so it’s safer to leave snorkelling to two or three days
after a flight. Snorkelling from a boat may also increase your chances as you are very quickly out
of your depth and in gear that you haven’t gotten used to yet, if you’re snorkelling from a boat,
take it easy and stay close to floatation before venturing too far, and if you can,
its best to stay in your depth where you can easily stand up if you need to.
And snorkelling should be done with a buddy and you check on one another,
as well as how far you’re travelling from shore frequently, about every 30 seconds or so. And
you shouldn’t over exert yourself when breathing through a snorkel as that can accelerate ROPE,
take it easy and if you feel yourself working hard, slow down and stop, get out if you need to.
If you’re snorkelling and you feel a sudden and unexpected shortness of breath and fatigue. Take
off your mask and snorkel, signal for help, turn on your back, calm yourself, breathe slowly, and
kick to where you can touch the bottom and stand out. Get out of the water ASAP. Don’t ignore those
kinds of feelings because those can be the little red flags that lead to something more serious.
You can Read the final reports of the Snorkel Safety Study here and I’ll pop
links to additional information down in the description under this video.
The bottom line is to take snorkelling seriously. I know we go far deeper while diving but,
a lot of those who answered the questionnaire after getting into trouble themselves were
described as strong and confident swimmers and when you’re investing in a new snorkel,
make sure that it’s from a reputable brand with decent air flow. Remember to subscribe to the
scuba diver magazine channel to stay up to date with the latest scuba diving news as well as tips
and advice videos and articles on how to dive more safely, where to go diving and what gear to use
so please subscribe to the channel. Thanks for watching everybody and safe diving.