Breath Retention

Beloved Dhananjay,

I can hold my breath for 18 seconds over 6 sets during pranayama. When I am about to finish my exhale after my first few sets, my abdomen and diaphragm jerk a bit, but I still try to control it all the way out. Is this unhealthy?

I smoked cigarettes for 2 years, and I do not anymore. I have a small wheeze. I feel that my lungs could use some sort of yoga technique to speed their recovery and cure my wheeze, which I hear when I force my breath out. Do you have a recommended technique for such a situation?

Thank you,
Erik Messick