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
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

Just how clean is that water container?

If you’re drinking water when recreating (and you should be), how important is choice of container to the cleanliness of the water? Proponents of water bottles certainly show how much easier they are to clean than your average hydration bladder. But does this make a difference?

Well, according to this paper, no. At least not in this convenience sample of people using one of 3 trailheads outside Albuquerque, NM. They were cyclists, hikers, or runners who were simply asked if they could have their water tested. They ended up with only 67, but that was more than they needed based on a power calculation for 20% difference between the two.
The total CFUs for each type was low (37 for water bottles, 27 for hydration bladders), which made finding a difference difficult without a much larger sample size. And even if it had reached statistical significance, such a small difference in colony forming units likely wouldn’t really matter in the real world.

The authors were correct that multiple potential biases could have been present. These include simply lying to the investigators about cleaning methods to appear “better”,  forgetting how long they’ve owned the container, and missing the more “hardcore” athletes who simply wouldn’t stop for the surveys. Most importantly, since these were trails close to civilization, nearly 90% were filled with municipal water that may have slightly disinfected the device.

The main problem I have with this is they didn’t get the water through the tube in the group using hydration bladders. Certainly the rationale was there (trying to avoid contamination from oral flora), but the tubing is the hardest part to clean and thus most likely to be colonized. Future studies should look into a way of controlling for this while measuring the water from the orifice used for consumption.

Based on this study, if you’re recreating near a city using municipal water, it doesn’t matter what type of container you put your water in. Just make sure and clean it regularly. I agree with the authors that applying this data to water that is potentially contaminated is more troublesome. It probably still doesn’t matter, as you should be decontaminating that water via whatever method you choose anyway.

A comparison of bacterial colony-forming units in water bottles and hydration bags among outdoor enthusiasts.

Sailing expeditions gone wrong

Ah, sailing. The joy that can be had utilizing just the wind to move effortlessly across the water. At least, that’s what it looks like to the untrained observer. Even casual sailing requires a bit of effort, and if there’s a race involved, the work can be quite strenuous. Combine this with the boat changing direction frequently, often while the rigging is also moving about, and you end up with injuries.

But how do you figure out the common injuries to better prepare for them, or better yet, prevent them altogether? The authors of this paper chose the time-honored method of the internet survey. Ignoring what I said last week about the internet, it certainly allows for greater numbers than you would expect to get in a single site clinical survey. This likely results in reporting bias, as does the fact that in this survey, the average time spent sailing was 65 days per year. Certainly not a beginner group, which would reduce the number of injuries. Also, no fatal injuries were reported by third parties using the surveys, so at the extreme end of injury (death and serious disability) there would be an absence of data as well.

With that out-of-the-way, what were the injuries self-reported by this grizzled group of sailors? Mostly extremity injuries, including contusions and lacerations. Upper and lower extremities were both nearly equal at around 40% of the injuries. Head injuries represent around 10% of the total, and are almost always from the boom or spinnaker pole coming across during a jibe or tack. All of these injuries are broken down into finer detail in the paper, in case you want to know the exact percentages of knee contusions versus leg contusions.

An interesting finding was that fractures are more common in larger keel boats than in smaller dinghies. This is straightforward, as not only are all the things that can break you larger on a keel boat, there often aren’t as many open hatches to fall into on a dinghy. Nearly half of the injuries were minor enough to not need treatment, and only 4% required “evacuation” or “hospitalization”, which sounds like an interesting composite end point. However, there were still a fair amount of injuries that did need treatment, some quite serious.

From these data, certain events that lead to injury can be identified. Jibes in high wind (whether planned or not), falls through hatches or companionways, rig failures, and collisions all have high injury rates. Heavy weather, fatigue, poor communication, and inexperience all contribute to injuries as well. Most injuries occur in the cockpit, but most time is spent there as well.

A smaller part of the paper is devoted to maritime illnesses. Unsurprisingly, more than half were sunburns. Seasickness was next in frequency at nearly a third, and then you get into the single digit rates for hypothermia and dehydration. Prevention is key for these, because if you’re down a crew member, the rest have to work harder to make up the difference, increasing their risk of injury.

An important thing to note from this survey is the self-reported poor use of lifejackets. Only 30% reported using them. Allow me to be clear, the lifejacket isn’t there because you can swim, it’s there for the times you can’t. 2/3 of deaths on the water are caused by drowning, and the majority of those occur while not wearing lifejackets. Other concerning safety behaviors include alcohol use prior to injury (clearly underreported), as well as poor compliance with sunscreen recommendations.

A final point is that their injury rate of 4.6 per 1000 days of sailing is markedly different from earlier studies that had rates of 0.29 and 2.2 injuries per 1000 hours. Thus, while nobody can clearly pin down the injury rate, the ballpark number shows it isn’t the most dangerous recreational activity out there.

Sailing Injury and Illness: Results of an Online Survey