The effect of air or enriched air nitrox breathing during simulated diving on intravascular bubble formation following decompression

Comparison of bubble formation after diving with air or nitrox using cardiac ultrasound (Comparaison par echocardiographie Doppler du phenomene bulleux a l’issue d’une plongee a l’air et au nitrox)

Status

Active, not recruiting

Phases

Unknown

Study type

Interventional

Source

ISRCTN

Registry ID

ISRCTN31681480

Enrollment

Registered

2016-03-25

Start date

2002-07-03

Completion date

Unknown

Last updated

2023-05-08

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Decompression illness in hyperbaric medicine Injury, Occupational Diseases, Poisoning Caisson disease [decompression sickness]

Interventions

The 47 divers underwent an initial simulated air dive to exclude subjects with low intravascular bubble production (Bubble score = 1) in order to select divers with high bubble production (Bubble scor

21% oxygen) and one simulated dive breathing enriched air nitrox (EAN) with 36% oxygen in a randomized order.

Eligibility

Sex/Gender

All

Inclusion criteria

Inclusion criteria: 1. Forty-seven human volunteers 2. Age >18 years 3. Diving experience as confirmed by possession of a French recreational diver license 4. Absence of contraindication to dive

Exclusion criteria

Exclusion criteria: 1. History of decompression accident(s) 2. Oxygen administration or diving within 24 hours before simulated dive 3. Absent or low intravascular bubble production (Bubble score = 1) after initial simulated test dive

Design outcomes

Primary

Measure	Time frame
Pulsed Doppler measurements of the trunk of the pulmonary artery in order to quantify intravascular bubble formation. Measurements of at least 1 minute duration were performed by a certified cardiologist, blinded for the FiO2 at 0, 30, 60 and 90 minutes after decompression. Images were recorded and analyzed for bubble scores offline. A modified bubble score was used, based on the Doppler score system of Spencer. Bubbles scores were analyzed independently by two blinded reviewers.	—

Measure

Time frame

Pulsed Doppler measurements of the trunk of the pulmonary artery in order to quantify intravascular bubble formation. Measurements of at least 1 minute duration were performed by a certified cardiologist, blinded for the FiO2 at 0, 30, 60 and 90 minutes after decompression. Images were recorded and analyzed for bubble scores offline. A modified bubble score was used, based on the Doppler score system of Spencer. Bubbles scores were analyzed independently by two blinded reviewers.

—

Secondary

Measure	Time frame
Decompression incidents by questionnaire 90 minutes after completion of the simulated dive.	—

Countries

France

Outcome results

None listed

Source: ISRCTN (via WHO ICTRP) · Data processed: Feb 4, 2026