My PhD title is 'The effect of apnea on blood flow dynamics'

Apnea is the suspension of external respiration. Under resting conditions the intervals between successive R peaks of the ECG of a healthy individual exhibit considerable variation. It is known that respiration has a significant effect on the interval between successive R-R peaks. The interval decreases during inspiration, and increases during expiration.

“Free divers” can readily suspend external respiration for sustained periods. Several British free divers can achieve breath holds in excess of 5 minutes. In such subjects it is possible to observe blood flow dynamics in the absence of external respiration. A major aspect of my PhD is to explore the dynamics of ECGs in the absence of respiration. It is possible that despite the absence of external manifestations of respiration there may still be an internal 'respiratory oscillator mechanism' which couples to the heart rate dynamics. It is also possible that the absence of respiration may affect the very low frequency oscillations observed in the diameter of very small blood vessels. This will also be explored as part of my research.

Free divers are generally very willing subjects as they recognise that relatively little is known about how their bodies adapt to permit extended breathholds. At Lancaster we have been fortunate that several national champions are contributing to our research as volunteers. One of these is the Norwegian ladies champion, Elisabeth Kristoffersen; see her blog.