Rob Casserley

‘My name is Rob Casserley, medical doctor and high altitude climber. I have summited Cho Oyu twice and Everest four times. I have used supplemental oxygen on all occasions and have experience with both the Poisk mask (1st generation) and the Topout mask. Topout has revolutionised the way big mountains are climbed. You don’t need to be a medical practitioner to know that oxygen deprivation is a major contributing factor to the reason why climbers fail to summit Everest, safely. Massive fatigue, frostbite, pulmonary & cerebral oedema are all problems caused by hypoxia (low oxygen levels) and so an efficient oxygen delivery device is an essential if this is your ‘one shot’ at Everest.

Topout has a working resevoir bag that allows you to inhale a higher concentration of oxygen for every breath, even at the same flow rate as other masks and there is no wastage of oxygen during expiration (breathing out) as the flow is directed into the reservoir bag. This makes it the best delivery device out there and the most oxygen efficient, meaning 2 things:

1. You can travel faster
2. Even at the same speed, you don’t use as much oxygen – allowing you to climb longer and use less oxygen

An additional benefit, is that it is smaller than the Poisk, which improves visibility no end and you don’t get that irritating thing that happens when the mask pushes up your goggles in to your eyes – that helps absolutely nobody!

Basically, Topout has made the mountain lower – it has made it more accessible – even to those who might have ordinarily struggled. It has enbled climbers to enjoy the experience and therefore retain the most amazing memories of what can only be described as a life-changing experience – to stand on the summit of the world…

Finally, Ted’s a great bloke, who’s really passionate about this project. He has developed the mask from start to finish and knows it inside out. I have no interest in writing such a positive statement – other than to help you improve your chances of making it to the summit.

Good luck,

Rob Casserley’

From Dr Andrew Sutherland of the successful Everestmax Expedition

Dear Ted,

I found the the Topout oxygen delivery system excellent.  At 7500m we measured our oxygen saturations at rest and they were about 95% – almost as high as at sea level.  On exertion between 7500m and 8000m my saturations were 73% (on 2L/min oxygen).  This compared to 54% on air the previous day. Unfortunately I could not compare it directly with a Poisk mask as we didn’t have one up at that height.  I can say that I climbed very well on oxygen and I am confident that this was helped by the Topout system.

At the summit I took my mask off to radio back to base camp.  During this time the valve froze up but I was able to clear this easily.  Some members of our group had more problems with their mask freezing up but this was partly due to the fact that they didn’t know how to clear the ice. One thing I would have found useful is a table with direct comparison with the Poisk system.  Most climbers use 2L/min with the Poisk system.  I used 2l/min with the Topout but I suspect I could have used less but I didn’t want to take the risk!  I understand Jeremy Windsor may be doing a study next year on the Extreme Everest expedition – I think this would provide some very useful information.  The crucial data is how the different systems help our oxygen saturations on exertion.

Best wishes,


British Military Reserves - Dr Raj Joshi Army Expedition Doctor

“I was fortunate enough to summit Mount Everest. I was in a team of 8 and every single one of us summited on the same day. It was notable that we all used the Topout system. In my opinion a large factor in our team’s success was due to the Topout system. I have used the old oxygen system in the past but have found Topout to be less cumbersome, with improved oxygen delivery and better line of vision due to the excellent mask design.

A good supply of oxygen not only helped us move faster but enables one to think more clearly which is crucial in decision making.

The Topout system not only allowed us to successfully summit but more importantly make it back down with our lives and digits intact.”

Dr Raj Joshi Army Expedition Doctor

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