#Chimborazo2015 Expedition Post 9: Gill’s Blog - What’s wrong with my blood?
Published on October, 22nd 2015
By Greg Wells
So I’ve finally stopped being sick and am feeling, dare I say, something that resembles acclimatized. Living at 4000 m and making daily trips to >5000 m is starting to feel manageable, if not normal. I’ve noticed that when we’re climbing uphill, if I focus on my climbing rhythm, despite the incessant pounding in my chest and heavy breathing, I am finding a steady state that is bordering on enjoyable (or in my aside to Greg “some sick part of me is actually enjoying the climbs”).
Although I’m feeling stronger and better adapted, my heart rate and my blood oxygen saturation continue to be well below Greg and Sara’s and it’s really starting to piss me off. Today, we set out to climb a smaller (5020 m) mountain, which began with about 2 h of moderate uphill hiking through these incredible plant/earth formations called almoadilla (translation – “pillows”) covered in aurellia a green grass type plant with white flower – it was other worldly. It was rainy/misty and everyone seemed to be pretty introspective for this stretch. For me it was “I’m not sick anymore, I’ve been averaging about 1L of water more than the rest of the group every day, I’m feeling adapted and strong, why the hell is my heart rate still consistently around 140-150 bpm and why is my blood oxygen saturation so low? What’s wrong with my blood!?” We’ve been using a portable blood analyzer (iStat™ by Abbott Diagnostics) to measure a few blood components every morning and night, including pH, glucose, hematocrit (percent of blood cell volume in your blood), hemoglobin (oxygen binding molecule in red blood cells), glucose, electrolytes, etc. Among these is one called BEecf, or Base Excess, which is more or less an overall composite of your blood’s alkalinity (opposite of acidity). This is the only measure that I could recall being different from Greg and Sara.
As an acute or short-term adaptation to altitude, your blood becomes more alkaline by virtue of hyperventilation. When you hyperventilate, you expire more CO2 than your body is producing metabolically – this causes a shift in buffers in the blood to bind hydrogen ions so that your blood become less acidic and more alkaline. The purpose of this accommodation is that when the blood is more alkaline the oxygen-hemoglobin dissociation curve (or how attracted oxygen is to the hemoglobin molecules on red blood cells) shifts in favour of binding oxygen at the lungs. The opposite of this is when your blood is acidic, it favours off-loading oxygen – this can be important when muscles produce a lot of lactic acid because it promotes the delivery of oxygen for aerobic metabolism. At altitude, this is helpful since the lower partial pressure (or concentration) of oxygen in the environment reduces its availability for binding to red blood cells passing the tissue of the lung. When your BEecf is greater, your blood is more alkaline, and you are able to more effectively bind oxygen in the lungs in the extreme environment of altitude.
This difference between me and Greg and Sara is key. My hematocrit has settled around 46% of volume (roughly the same as Greg’s and slightly higher than Sara’s) and we all have hemoglobin content around 15-16 g/dL. So this means that we all have experienced a similar increase in red blood cell numbers and accompanying hemoglobin content, yet I am the only one who is climbing with 65% the amount of oxygen in the blood as at sea level and a heart rate that would have cardiologists concerned.
So this leaves me to believe the shift in the oxygen-hemoglobin dissociation curve due to differences in blood chemistry is the culprit. I guess, technically speaking, nothing is wrong with my blood, I just didn’t spend my formative years as an athlete holding my breath racing in a swimming pool and unknowingly making my body used to dealing with high CO2 levels – or at least that’s my speculation because it can’t be fitness. It just can’t be.