Thursday, July 24, 2014

Review: HDM Z1 CPAP

Two weeks before my 2014 Tour of the Alps, my doctor told me about the HDM Z1. Now, I've been very happy with my ResMed S9. It's quiet, durable, and works well for sailing. However, even with the portable 30W power supply the entire package weighed 40oz, discounting the hose and the CPAP mask. For a cycle tour with big mountains, this was not ideal, and the HDM Z1 at half the weight of the ResMed S9 was very appealing.

There are a few issues with this machine compared with the S9:

  • It is much louder. After comparing this machine with the S9, Arturo found that the S9 was almost silent in comparison. Subjectively, I rate the difference between the machines at 5dB. The HDM Z1 was so loud my wife refused to let me test it. One interesting thing is that adding the HME to the tube makes the machine quieter, which indicates that the increased noise isn't just due to the louder air pump, but also to do with the resonant frequency of the output into the hose.
  • For at home use, there's no elegantly integrated humidifier like the S9. Instead, you buy a Fisher & Paykel humidifier, or you use a HME. HMEs are consumables, and each one is good for only 7 days, which at $6/pop is significant over the usual 2 year depreciation period of a CPAP machine. Since you'll almost certainly need to travel with HMEs, the HMEs add some bulk but not significant weight to the final package.
  • The ResMed S9 is an auto-PAP, adjusting pressure according to how much you need to avoid apnea events. The Z1, however, is a fixed pressure CPAP, so you only get to set one setting, and live with it for the entire trip. My 95% pressure was 9, so that's what I used. I initially didn't think there was much difference for me, but at the end of the trip, I switched back to the S9 and immediately felt more refreshed after a night's sleep, indicating that the auto PAP algorithm on the ResMed is more effective and provides better sleep.
  • There are reports as to the robustness of the machine, with some users reporting failure after 4 weeks of use. HDM offers a 2 year warranty, but that's of no use to you while you're traveling if your machine fails! My trip was only 3 weeks, so I decided it was worth the risk.
Was this enough to offset the 20oz difference between the ResMed and the HDM Z1? No, so if you've been hankering to an independent bicycle tour and the weight/bulk of carrying a CPAP was putting you off, stop reading and just buy it now.

The machine itself is interesting. it comes with the machine, which weighs in at 10oz, and a power supply, which also weighs in at 10oz. I was wondering why the power supply hadn't gone in for more weight reduction, but that's probably because the machine is rated for higher pressure than I use, and so the power supply has to handle that, rather than my relatively low pressure rating. It comes with an adapter for use with the standard CPAP hose. The adapter basically splits the hose so the pressure measuring system can be separated from the output of the pump. You could just leave the adapter in place all the time, but I wouldn't recommend it while traveling, since the tongue of the adapter is in a particularly highly leveraged place, which would cause it to break off.

The machine comes with a micro-SD slot, but I didn't have time to buy a micro SD card to put in the machine, so did not test the software or get details about my apnea events while using the machine. Given that the primary symptom of my apnea is incredibly loud snoring and my roommates did not kill me while I slept, however, I think we can safely say that the machine works.

You can buy a Powershell battery for the Z1, which is basically an integrated battery for camping and other off-the-grid uses. The battery is also incredibly light at 200g, with the downside being that you can only charge the battery with Powershell, so you can't charge multiple batteries at once, for instance. Since the Tour of the Alps is a hotel-based credit card tour, I opted out of buying one and did not test it.

The biggest feature of the machine, however, is the weight and size. It's truly remarkable, and done (as far as I can see) without exotic materials like carbon fiber, titanium, or magnesium, which means that there's ample room for even lighter, more premium versions. The cost of the machine is around $600, which is affordable and much cheaper than a planet ticket to Europe these days. The cost/weight reduction ratio is much better than the typical weight reduction measures on bicycles, so this represents an exceedingly good deal for cycle tourists who carry their own baggage.

All in all, I'm very impressed, and would highly recommend this product.
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