Question: 

Knowing that the site of pulmonary gas exchange is solely restricted to alveolar level, remaining parts i.e. conducting zone of the respiratory system is physiologically entitled as "Dead Space". Since the alveolar volume (VA) and the dead space volume (VD) are not anatomically separated from each other, VD pursues indirect contribution in gas exchange by being the site where the later inspired air and earlier expired gases are mixed. Here we report about the impact of artificial dead space volume (VDA) variations on gas exchange.

Methods: 

The anatomical VD of adults ([asymp]150ml) was increased by VDA as an annex to VD. VDA was altered gradually from 0ml to 450ml by different geometrical devices to investigate the effect of an increasing VDA, revolving flow resistance fluctuation.

Results: 

Probes of expired respiratory gases from healthy volunteers were measured. Mean average values have shown a decrease of 5mmHg/100ml of VDA on expired PO2.As well as an increase of 3.2mmHg/100ml of expired PCO2. Identical VDA modules with 50% reduced resistance show a decrease of expired PCO2 by 13mmHg and an increase of expired PO2 by 8mmHg.

Conclusion: 

It is clearly shown that variations either of VDA or its flow resistance could be detected reproducibly through respiratory expired gases. The investigation could be applied in sport medicine or even for therapeutic suggestions.