Mechanical constraints to ventilation play a role in the limited exercise endurance seen in adult survivors of very preterm birth.

Adult survivors of preterm birth have a clearly obstructed airflow pattern and when we reduce some of their airflow resistance they can exercise longer, "Dr. Duke told Reuters Health by phone.

The adult etiology of these differences remain unclear, impaired pulmonary gas exchange efficiency, mechanical ventilator constraints and / or dyspnoea, "he and his colleagues note in in Thorax, online September 14. 

Preterm birth

Dr. Duke and his team previously showed that adult survivors of very preterm birth have expiratory flow limitation during exercise.In the new study, they tested whether breathing heliox – in which the nitrogen in normal ambient air is replaced with helium – would improve time to exhaustion.They enrolled 19 adults who had been born at least eight weeks premature, regardless of whether or not they had bronchopulmonary dysplasia.

TTE improved significantly in PRET when they breathed heliox compared to normal air, the researchers found, but breathing heliox did not affect TTE in controls.While there are some similarities between adult survivors of very preterm birth and people with mild COPD or asthma, Dr. Duke noted, the etiology of their lung obstruction is likely to be entirely different.

The real issue here is that these preterm born individuals, there's not really enough of their physiology that is known, particularly with the respiratory system," he said."The survival rate of people born premature continues to rise because neonatal medicine has been getting so good at keeping them alive," he added. "This problem isn't going to be a problem that goes away any time soon, thankfully."

This research was supported by an American Heart Association Scientist Development Grant #2280238 (ATL); American Physiological Society’s Giles F Filley Memorial Award for Excellence in Respiratory Physiology and Medicine (ATL); Medical Research Foundation of Oregon Early Clinical Investigator Award (JWD) and Ohio University Research Committee award (JWD).

In PRET, EFL decreased and time-to-exhaustion increased significantly while breathing heliox. Heliox had a minimal effect on EFL and had no effect on time-to-exhaustion in CONT. We conclude that aerobic exercise endurance in PRET is limited.