Decompression sickness is known to be due to the formation of bubbles in the body as a result of decompression. It is likely that these bubbles form from pre-existing nuclei, which, for bubbles in the bloodstream, are thought to be housed within blood vessel walls. Gas pockets emerging from these sites will be subject to forces due to blood flow, a portion of the gas eventually being swept away to form a free bubble in the bloodstream. These continue to grow and may grow to similar dimensions to the vessel, developing into elongated "gas plugs," potentially occluding the flow. In this correspondence, we derive a simple model to investigate whether this vessel occlusion is a serious concern.