Hi JustJules,
.... is breath holding on ascent, or ascending faster than air can be vented from the lungs even in the absence of breath holding.
Medical factors that may contribute to the risk of DCI conditions of the type you have referenced include asthma, bronchitis, blisters on the lung (cause largely unknown) & damage from tuberculosis.
I am not aware that obesity per se contributes to the risk of dive-induced subcutaneous or mediastinal emphysema, but it is a risk to general health, especially cardiovascular health, and may be problematic when the exertional demands of a dive become great. There is a fair amount of data suggesting that obesity is related to increased DCS risk, apparently due to the gas solubility properties of fatty tissue.
One would hope that the buoyancy issues occasioned by obesity would have been solved early in the diver's training.
This is educational only and does not constitute or imply a doctor-patient relationship. It is not medical advice to you or any other individual, and should not be construed as such.
Best regards.
DocVikingo