2min CO2 table HR graph

[ADR]

I'd be interested in anyones thoughts/interpretations of the following HR graph over a 2min CO2 table. I've drawn some conclusions from the data and would like to see if they are echoed by anyone else.

some related info
- contractions in each effort began at about 1min
- each hold was 2 mins (full inhale/no packing)
- 1st rest was 2mins and then they reduced by 15secs each time

thanks in advance

 

[sebastien murat]

Thought?:

CO = SV x HR

Large lung volume -> impeded venous return -> lowers stroke volume -> heart-rate increases to compensate and maintain CO. During rest tachycardia to off-load CO2 and recupe O2 stores


Subsequent trials -> reduced heart rate due to better venous return (progressive 'dive response')


Seb

 

[sebastien murat]

PS: HR decreases during holds because of little dive response and increased vasoconstriction

Seb

 

[ADR]

Thanks for the thoughts Seb, what are your thoughts on the decrease in HR for rests 1,2,3 and a plateau for 4&5 and an increase for 6&7? Given the tachycardia is most pronounced in the last two rests, is it fair to say the CO2 table is doing exactly what it was designed to do?

.......a glimmer of a dive response there is rather a nice surprise!!

 

[sebastien murat]

First impressions: hard to say with going invasive.

As at a guess, I would say that:
1,2 & 3 the body has got enough time to off-load CO2 but needs to do this quickly, hence the elevated heart rate. Susequently, 4 & 5, its anticipating another imminent breath-hold and so is delaying CO2-off-loading (& since this would also result in the rapid rise in O2 consumption) storing the excess in the peripheral tissues, until as such time it becomes excessive and, or it anticipates termination of the trials, i.e., 6 & 7. Indeed, note the 8th and final rest/recovery and the particularly elevated HR.

Seb