Category Archives: water

SteriPEN, convenient or worthless?


Clean water is of utmost importance, whether you’re backcountry hiking, camping, or travelling abroad. And there are many ways to disinfect water, including chemical tablets, mechanical filters, simply boiling, and ultraviolet light. And while we know that UV light from the sun works with enough contact time, does a handheld UV light work well enough to be safe?

They’ve been around since the late 90s, but decreases in size and cost have made them more popular recently. They are lighter than ceramic filters, don’t require heating and then cooling the water, and they don’t leave a funky taste in the water after use. And while you can go to SteriPENs’s website and see a bunch of articles they sponsored showing how awesome they are, it’s nice that an independent group has finally looked into their effectiveness.

One of the things the article points out is that UV light is bacteriostatic, not bacteriocidal. Their DNA is damaged, so they can’t reproduce or cause infection (probably), but the water is disinfected, not sterile. Also, while still effectively treated by UV light, viruses and spores require much higher doses to be inactivated.

They tested the function against of the SteriPEN against water bottles contaminated with Escherichia coli, Staphylococcus aureus, and the spore of Geobacillus stearothermophilus. Using 1 L bottles in 3 different styles (wide mouth reusable, narrow mouth reusable, and disposable narrow mouth bottles), they either agitated as per the instructions for the device, or let the water remain calm. For wide mouth containers, you can stir. With narrow mouth bottles, you need to plug the mouth with the pen and invert and shake. However, knowing that many people don’t do this, they also did a test by simply stirring the narrow mouth bottle as well. They also measured the spectrum emitted by the device during use.

Used correctly the SteriPEN works pretty well. Bacteria counts were reduced more than 99.99%, but spores were only reduced 99.57% on average. If you don’t agitate the water, this drops to 94.2% on average. The SteriPEN does emit its maximal intensity of UV at 254nm, which is the most efficient wavelength for bacterial DNA. And in a bottle made of glass, PET, or metal, there’s no risk of UV injury to the user, as it’s all blocked. However, in a big open-topped pot, there’s a risk of UV emission that could be hazardous to the eyes. Thankfully, the device won’t turn on if not immersed in water.

Therefore it is ok to use a SteriPEN to disinfect your water, as long as you’re doing it right. You’ve got to agitate the water, not just put it in and let it sit there. These authors also didn’t test against viruses, but the manufacturer does have data, and since this paper replicates some of their other results, it’s not unreasonable to state that it likely works against those as well.

Downsides are a few. 4 AA batteries only gives you 100 cycles and the bulb is pretty fragile, so pack extras. It doesn’t filter out toxins, and turbid water decreases efficacy, so you might night a filter anyway. This particular device has 2 settings, 90s of light for 1L containers, 48s for 0.5L ones, so you’ll need to make sure you have it set for the correct size as well. Finally, it doesn’t keep the water disinfected forever, so be aware that the water can become contaminated again and require re-treatment.

Drinking water treatment with ultraviolet light for travelers – Evaluation of a mobile lightweight system
http://www.travelmedicinejournal.com/article/S1477-8939(15)00174-X/abstract
And it’s FOAMed!

Don’t use compression-only CPR for drowning victims

Vasily Perov: The drowned, 1867

Compression-only CPR has improved bystander participation and patient survival for OOCA. Advertisements on television and in print media have done a good job of increasing layperson awareness of this modality. And for many patients, it’s the right thing to do. But only if the etiology of their cardiac arrest is cardiac in nature. As is explained in this short little “article in press” that’s actually a letter to the editor, this can ignore the true cause of arrest in drowning victims and decrease their chance of survival.

In drowning victims, it’s primarily respiratory in nature, and they absolutely need ventilations. But how many of the ads for CCPR are that nuanced? I certainly haven’t seen any, and I would imagine many of the rest of you haven’t either. The major societies (ECR and AHA) are certainly aware of it, as their guidelines strongly urge proper use of respiratory support.

European Resuscitation Council Guidelines for Resuscitation 2015. Section 2 and 4.

“Most cardiac arrests of non-cardiac origin have respiratory causes, such as drowning (among them many children) and asphyxia. Rescue breaths as well as chest compressions are critical for successful resuscitation of these victims.”

“Most drowning victims will have sustained cardiac arrest secondary to hypoxia. In these patients, compression-only CPR is likely to be ineffective and should be avoided.”

American Heart Association (AHA) 2010

“CPR for drowning victims should use the traditional A-B-C approach in view of the hypoxic nature of the arrest”

“The first and most important treatment of the drowning victim is the immediate provision of ventilation.”

And since preventable drowning deaths can be due to improperly or not-at-all performed bystander CPR, this gap between the guidelines and the layperson needs to be closed by education. Anticipatory guidance for parents with pools, people who take part in watersports, and lifeguards can help, but really there needs to be a public campaign for CPR for drowning that’s similar to that of cardiac arrest of coronary artery disease. Specifically, any instructional materials need to address the dreaded mouth foam that can appear during resuscitation, as this is a major deterrent for anyone performing mouth to mouth.

So yeah, maybe we can dial back on the CCPR a bit, and focus on getting patients the best care available specific to their process.

A call for the proper action on drowning resuscitation
http://www.resuscitationjournal.com/article/S0300-9572(16)30043-0/fulltext