Science desk
< September 13	<< Aug \| September \| Oct >>	September 15 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

September 14

Defibrillator units

I was watching an early episode of Law & Order (season 2, episode 5 "God Bless the Child") in which hospital staff use a defibrillator in an attempt to resuscitate a small child. The doctor holding the paddles instructs a nurse to set the device to "18 watts per second". Now I'm no brilliant physicist, but if I remember rightly, watts are already joules per second. That would make this unit joules per second per second which would be rate of change of power. I googled around and there are other sources that refer to watts per second as the unit for defibrillation such as this one (which seems to get the relationship between joules and watts wrt time backwards). Some other sources quote doses in watt seconds, which would make more sense, as that reduces to joules but the terminology makes it clear to the operator that the machine is delivering a power for a time period. Does anyone know how the units of defibrillators are normally used in a typical hospital setting? 114.124.175.125 (talk) 00:49, 14 September 2018 (UTC)[reply]

Here is a great review article from the American Heart Association: Defibrillation - 2010 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations. It's part of a whole series of scientific review, published in the October 2010 issue of Circulation (Vol. 122, No. 16), in which a panel of experts detailed the scientific studies and made recommendations for clinical use.

In scientific literature, defibrillation is characterized using several parameters: among them are the paddle type and placement; the total energy; the waveform of the shock; the number of shocks; and the energy level per shock, measured in Joules.

In a clinical setting - like a hospital - scientific accuracy might be sacrificed during common use. If the machine is an AED - an Automated external defibrillator - the operator might have limited or zero medical and scientific training. Though in many places, use of an AED is restricted to only those emergency responders who have certain levels of professional qualification - in other places, the recommended procedure is for the first person near the victim - trained or otherwise - to use the machine. So you can see how the operator might mess up some of the details of the physics.

"Watts per second" is a nonsensical physical unit, at least in the context of measuring an electrical shock during a medical defibrillation procedure. Even if we're generous and we assume the fictional character misspoke, and meant to say "eighteen watts-times-seconds," that's equal to eighteen joules, and it's not a meaningful or reasonable quantity of energy for a defib. Defib shocks are normally in the range of 100 to 300 joules. The duration of time that this energy is delivered is very short - different machines use different waveforms, but all the energy is usually delivered in the first 15 or 20 milliseconds. Normally this would be characterized by describing the energy (in Joules) and the waveform (by naming it, out of a small set of common waveforms like "Pulsed Biphasic Waveform" or "Biphasic Truncated Exponential Waveform"). If the user were a physicist and felt like wasting time during the emergency, they might convert to using watts as the unit of measurement, and compute somewhere between 1 and 2 kilowatts during the application of the shock.

As always, the easy way out is to forgive a little poetic license in a work of fiction - they shouted some technobabble for dramatic effect, and the show's writers probably spent less time researching the topic than I did just now. But hey, in addition to being a volunteer science-enthusiast, I'm also a volunteer emergency-responder and I like to know a little bit of theory in case it ever saves a few seconds during an emergency.

You can sign up to learn more about AEDs; a great resource that's probably available in your community is the Red Cross AED training class - they'll probably encourage you to get a CPR refresher too. "The average response time for first responders once 911 is called is 8-12 minutes. For each minute defibrillation is delayed, the chance of survival reduces by approximately 10%." Or, as I like to phrase it: the professionals are, by definition, the second responders to your emergency: you are the first responder - so why not take some time to prepare for it now?

Nimur (talk) 05:00, 14 September 2018 (UTC)[reply]

Eighteen joules is certainly a reasonable quantity of energy for a pediatric defibrillation (as implied by the original question). Generally the "dose" is 2 J/kg for the first attempt, so 18 joules is right for a 9 kg (20 lb.) child. - Nunh-huh 19:12, 14 September 2018 (UTC)[reply]

I second what Nimur said about the value of getting even minimal training. AEDs are widely deployed in public places now and stupid-easy to use. Some are just "slap the pads on two places on the chest--there is a pictograph on the pads themselves and it doesn't matter which goes where; press the big button and then follow the instructions that the device's voice tells you" (things like "call 911; hands off; shock delivered" and a metronome for chest compressions). And hands-only CPR is pretty simple too (plus a great soundtrack!). Some key AHA data are that the survival rate for cardiac arrest that occurs outside of a hospital setting in communities where AEDs are available and people have AED/CPR training is nearly 40%, vs <10% overall. Part of the basis for improvement is that 23% of those patients initially have shockable rhythms. DMacks (talk) 15:16, 14 September 2018 (UTC)[reply]

I agree that it's useful to be trained in AEDs (even a bonehead like me can follow their instructions), but they're entirely a side issue to the question. The OP specified that the scene took place in a hospital, not at the scene of a first respondent attempting to use an AED. Matt Deres (talk) 17:05, 14 September 2018 (UTC)[reply]

Coming back to the original scenario (thanks Matt Deres for keeping us loosely on track!), doi:10.1001/jama.2010.1576 has the interesting conclusion that "Among hospitalized patients with cardiac arrest, use of AEDs was not associated with improved survival." It had no statistically significant effect on those with shockable rhythms (and these accounted for a lower percentage of patients than out-of-hospital case) and a detrimental effect on those without shockable rhythms. They propose that a major effect is that AED delays CPR and other emergency treatment actions. A systematic review study[1] reminds that although AEDs in hospitals are not effective, the basis for comparison is normal external defibrilation (which is presumably promptly available in that setting). I haven't yet found data for effectiveness of non-external. DMacks (talk) 22:38, 14 September 2018 (UTC)[reply]

Did Prohibition Reduce Drinking?

Our article on Repeal of Prohibition in the United States says that:

Alcohol consumption declined dramatically during Prohibition.
Violent crime did not increase dramatically during Prohibition.
Organized crime did not increase during prohibition.

There are indeed some sources that support at least some of those claims,[2][3] but a `quick web search also finds:

So which view is supported by the sources? Or could it be, as one source says, "In truth, nobody really knows exactly how much alcohol consumption increased or decreased during Prohibition. The reason was simple enough -- people like Al Capone didn't pay taxes on their product and thereby report their production to the government. Licensed saloons became illegal speakeasies, and many common citizens took advantage of the high sales price of illegal booze by secretly manufacturing booze in their own bathtubs."? --Guy Macon (talk) 04:43, 14 September 2018 (UTC)[reply]

And don't forget the yeast-flavored grape juice that would "go bad" if you added sugar and then waited. Anyway, regarding at least the first point, it is true that the certainty on this is pretty shit, and scholars bicker over the flaws in any method, but as far as I can tell, all the indirect evidence points to a singular conclusion: alcohol consumption declined a lot. Both contemporary and modern estimates of illegal alcohol production and consumption are vastly below the surrounding time periods, arrests for public drunkenness declined by two thirds, deaths from alcohol related illnesses declined by 80%... I'd say that there are arguments that the mainstream view is wrong, or poorly supported by the evidence, and it's certainly true that all available evidence is circumstantial, but it seems pretty damned uniform in where it points: [4]. Someguy1221 (talk) 06:16, 14 September 2018 (UTC)[reply]

Deaths from alcohol related illnesses declined by 80%?

"Deaths from Alcoholism. In New York City, from 1900 through 1909, there was an average of 526 deaths annually attributable to alcoholism.

From 1910 through 1917, the average number was 619.

It plummeted to 183 for the years 1918 through 1922.

Thereafter, the figure rose, averaging a new high of 639 for the years 1923 through 1927.

Total deaths from alcoholism in the United States show a comparable trend, with the gradual increase resuming somewhat earlier, about 1922."

"These statistics should be qualified by the observations of Dr. Charles Morris, Chief Medical Examiner for New York City: 'In making out death certificates (which are basic to Census Reports) private or family physicians commonly avoid entry of alcoholism as a cause of death whenever possible. This practice was more prevalent under the National Dry Law than it was in preprohibition time' ".[5] --Guy Macon (talk) 07:15, 14 September 2018 (UTC)[reply]

80% decline is the figure from Gebhart, J. C., Statistical studies of enforcement and social effects, 1930, which is based on contemporary nation-wide statistics, though I can't find an online version. Specifically 5 per 100,000 persons per year prior, dipping to a low of 1 per 100,000 during. Notably, Gebhart was actually anti-prohibition, and believed certain causes of death were under-reported (indeed, it is today a point of contention with this type of measure that at the time, there was no consistent nationwide reporting of causes of death, and standards varied over time in particular places). Someguy1221 (talk) 07:31, 14 September 2018 (UTC)[reply]

And yet The Effect of Alcohol Prohibition on Alcohol Consumption[6] by Jeffrey Miron [7] of the National Bureau of Economic Research says "The overall conclusion of this paper is that Prohibition exerted a modest and possibly even a positive effect on alcohol consumption". So alcohol deaths dropped by a whopping 80% while alcohol consumption stayed about the same? Is there something extra healthy about bathtub gin? Or did Gebhart's 1930 figures simply reflect that during prohibition physicians avoided listing alcohol as a cause of death? --Guy Macon (talk) 12:32, 14 September 2018 (UTC)[reply]

The Miron study is however based entirely on the correlation between the number of deaths due to cirrhosis and alcohol usage (something the author somehow fails to mention in the abstract), since there is simply no real data on alcohol supply or demand in that period. The study does acknowledge one weakness of this method: cirrhosis is correlated mainly with heavy alcohol usage, and so may not be greatly effected by a decrease in casual alcohol consumption. A more solid conclusion from the study then would be to say that the number of heavy drinkers probably did not decrease significantly during prohibition. That is not to say that the total amount of alcohol consumed stayed the same. Also note that this is a working paper, so it has not undergone peer review (yet). - Lindert (talk) 13:13, 14 September 2018 (UTC)[reply]

Using cirrhosis as an indicator of alcohol consumption is an interesting idea. According to our article on it, worldwide 57% of cirrhosis is attributable to hepatitis, and 20% to alcohol consumption. In the US the (current) number is 40% alcohol -- probably because we have better treatments for hepatitis. I wonder whether those percentages hold in the 1920s and 1930s, and whether the incidence of hepatitis remained steady during that period.

Another interesting factor; a bunch of light drinkers consuming X amount of alcohol would result in less cirrhosis than a smaller number of heavy drinkers consuming the same amount. It's heaviy drinking that ruins your liver. I don't have any figures, but it is plausible that light drinkers were more likely to become nondrinkers once it became illegal.

There is also a matter of timing. Increased alcohol consumption doesn't cause an immediate increase in deaths by cirrhosis. It take a while to destroy your liver. A decrease in deaths by cirrhosis follows a decrease in alcohol consumption much quicker; livers that aren't yet bad enough to kill you start healing if you stop drinking. The two are certainly cause/effect related, but it isn't a simple one-to-one correlation. --Guy Macon (talk) 17:54, 14 September 2018 (UTC)[reply]

Death from cirrhosis can also go under-reported (if there is no autopsy). Ruslik_Zero 20:23, 15 September 2018 (UTC)[reply]

I wonder if the autopsy rate was different in the 1920s compared to the 1930s. The more I look into this the less I like the absolute certainty that is in our article. --Guy Macon (talk) 04:04, 16 September 2018 (UTC)[reply]

All of the 3 assumptions on Developments are based on official statistics, which seem most unfit to estimate black markets and their circumstances. Therefor any such assumption should be mentioned as "based on very limited official knowledge" due to their systematically hidden nature. --Kharon (talk) 10:59, 16 September 2018 (UTC)[reply]

There is an interesting article about similar anti-alcohol campaign. Ruslik_Zero 20:19, 16 September 2018 (UTC)[reply]

Internation standard

Is anyone having knowledge of international quality standard that are to be followed for equipment racks and enclosures. 112.133.223.2 (talk) —Preceding undated comment added 06:24, 14 September 2018 (UTC)[reply]

Try here: 19-inch_rack#Specifications 196.213.35.147 (talk) 06:56, 14 September 2018 (UTC)[reply]

Best also search for ISO-Norms (International Organization for Standardization). --Kharon (talk) 10:41, 16 September 2018 (UTC)[reply]

Unidentified farm crop

Can anyone help me identify the crop in this picture? Taken on 9 June at 36°20′58″N 76°59′53″W / 36.34944°N 76.99806°W / 36.34944; -76.99806; there were a lot of fields in the area with the same crop, and I can't remember ever seeing such a crop anywhere else. Nyttend (talk) 14:00, 14 September 2018 (UTC)[reply]

Looks like clary sage to me. 216.59.42.36 (talk) 16:40, 14 September 2018 (UTC)[reply]

To me too: https://www.ncfieldfamily.org/farm/on-the-scent-of-sage/ 194.174.73.80 (talk) 16:57, 14 September 2018 (UTC) Marco Pagliero Berlin[reply]

Another option is lavender, though the plants tend to form more rounded shrubs that you see in the OP's picture. Matt Deres (talk) 17:11, 14 September 2018 (UTC)[reply]

Per the clary sage article, "In the United States, large scale production is concentrated in northeastern North Carolina in the counties surrounding Bertie County, NC." This is just the next county north of Bertie. Thanks! Nyttend (talk) 17:19, 14 September 2018 (UTC)[reply]

Wikipedia:Reference desk/Archives/Science/2018 September 14

Contents

September 14

Defibrillator units

Did Prohibition Reduce Drinking?

Internation standard

Unidentified farm crop