A researcher from the Prince Charles Hospital in Brisbane has defined the time it takes for a lung transplant patient to reach their optimum lung function following surgery.

Presenting to delegates as part of the ANZSRS young investigator oral presentations Emma Smith said previous research quoting optimum lung function after surgery had varied as much as between 10 to 2949 days.

Patients are understandably curious as to how long their lung function will continue to improve after their transplant and our answer has always been “every set of lungs is different,” Smith told delegates.

It got her thinking that surely this was something that was easy to look up.

“But as I started to look into it there were two things that struck me. The first one was that there was no real consensus on how long it takes — there’s a really wide range.”

The second thing was that there were differing definitions of best lung function and maybe it was this that was contributing to the large discrepancy in results, she said.

So she decided to analyse 319 patients who had received lung transplants between 1996-2014 at her hospital. The final analysis involved 206 patients after some were excluded for incomplete/missing data or transplant having occurred too recently.

Result showed the best FEV1 was 3.04 L ±0.77  and the mean peak FEV1 was 2.98 L ± 0.78. The time to best lung function was just under two years, “with an enormous standard deviation”.

And the range was fairly similar to the study that quoted 2949 days, Smith said.

So they included patients who had undergone transplants in 2011 and 2013 in the analysis — they had previously been excluded.

The researchers then had a look at the single best FEV1 and took o.35L away from that to create a small but clinically insignificant range around it and calculated how long it took before a patient got into that range.

They found that while the mean time to FEV1 was 561 days ± 538, the mean time peak to FEV1 was 321 days ± 331.

Best lung function occurred within the first year after lung transplant, she said.

Expanding the definition of “best lung function to include a small range around the best recorded FEV1 can make a significant difference to the calculation of time before highest lung function is reached, but not the FEV itself, she concluded.