The impact of Patent Foramen Ovale (PFO) in diving

A heart condition that can be easily diagnosed which might save a life

A Pfo And Why It Matters

A Patent Foramen Ovale (PFO) is the opening between the two upper chambers of the heart — Atria Septum — the point at which a baby, while developing, is connected through the umbilical. Post birth this normally heals sealing both atria.

gas safely passes into blood stream after which the lungs perform to filter inert gas from body. However, PFO leads to inert gas shunting, passing between right to left Atria, and this circulates the same gas around the body again. The lungs are not able to filter gas bubbles effectively, compounding gas build up and pushing more gas into the saturated tissue increasing the risk of decompression illness.

Why it is relevant for diving is that, as we know, diving saturates the tissues with gases and, subject to the decompression tables, saturated

Numbers Of People With Pfo

How many readers, I wonder, have a PFO? A 1984 study at the Mayo Clinic (Hagen et al.) took 965 autopsy specimens of normal hearts to determine the incidence and size of patent foramen ovale during the first ten decades of life. The findings included that the prevalence of PFOs is evenly distributed by sex over all age groups but that there are age related variations.

with no previous history of sustaining a bend. The incident happened during a dive at a remote location with a maximum depth of 18m. There was, according to USN no.7 table, no decompression profile and the diver’s last dive under pressure had been seven days previous. The diver’s last Gym session had been three days before the dive and had consumed no alcohol nor had he experience any in-water exertion. The water temperature was 15 degrees but the diver reported feeling unwell overnight, with the sensation of pins and needles on the arm. He was treated on USN table 6 with a further 2 Table 6 treatments, then an additional table five treatment prior to repatriation to UK. On return to UK, diagnosed with a PFO.

Incident 2

Proposal

Each Dive team in the UK is highly likely to have at least one diver with a PFO but DCI (Decompression Illness) incidents reduce confidence in the industry and are turning clients away from diving. On top of that, HSE requirements are becoming ever more onerous and incidents are penalised at the highest level. Technology has enabled PFO scans to be readily available and inexpensive so we propose that, at the time of issuing first diver medical, the diver is scanned for a PFO and that the Certificate of PFO is maintained as part of diving documentation.

Incident Examples

Here are a couple of examples of incidents that were found to have been caused by previously undetected PFOs.

In this second incident, the diver was aged 27, male and experienced but with a previous history of sustaining a bend three months prior to the incident but that was not recorded. Again, the location was remote, Skye. The maximum diving depth was 27m. There was, according to USN no.7 table, no decompression profile for the diver whose last dive under pressure had been five days prior to the dive. His last physical exercise had been more than five days before the dive but no alcohol had been consumed and no in-water exertion had been experienced. The water temperature was 14 degrees. The diver reported feeling unwell post shower with a rash on his shoulder and chest. He was treated with O2 immediately then transferred to ABZ Royal Infirmary where he was given one USN Table 6 treatment. He was later diagnosed with a ‘Large’ PFO. The consultant was very surprised on that two DCI events were experienced.