Wikipedia:Reference desk/Archives/Science/2018 January 8

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January 8

Cardiopulmonary resuscitation, oxygen in mouth-to-mouth artificial respiration

Since we exhale CO2, why does mouth-to-mouth artificial respiration help by CPR? Should we expire the air as soon as we inspire, holding our breath as short as possible, so to pump more oxygen into a patient?

I have not seen any indications regarding this issue. But is the artificial respiration meant to pump oxygen at all, or just to 'jump start' the breathing in the patient? --Hofhof (talk) 00:39, 8 January 2018 (UTC)

You're beginning with a mistake: We don't exhale CO₂, we expire a mixture of gasses that includes about 4 to 5% more CO₂ than we inhale. That is, the chemical composition of exhaled air is about 78% nitrogen, 18% oxygen, and 4% CO₂ (plus lesser amounts of other gasses). This is sufficent to oxygenate blood when inhaled. - Nunh-huh 01:16, 8 January 2018 (UTC)

The relevant article is at mouth-to-mouth resuscitation, which uses slightly different figures for exhaled oxygen levels (and backs them with a citation). If Nunh-huh has a better reference, s/he should update the article. Matt Deres (talk) 01:50, 8 January 2018 (UTC)

17% and 18% isn't a significant difference. The ref I used isn't better than the one in the article, though a better reference than that one is desirable, - Nunh-huh 02:36, 8 January 2018 (UTC)

I would argue that it is. Air is only 20.9% oxygen to begin with, so a one percentage point difference is pretty significant in terms of respiration efficiency. I was hoping gas exchange would have something better, but I'm not seeing much discussion of oxygen percentages (though there is a lot of text and I'm not familiar with the science). Matt Deres (talk) 03:03, 8 January 2018 (UTC)

I find your argument intriguing, and would like to subscribe to your newsletter. When we were taught CPR, I asked this very question, and was assured that some oxygen is better than no oxygen, and that we exhale a rather large fraction (they weren't specific) of the oxygen we breath in anyways. μηδείς (talk) 06:05, 8 January 2018 (UTC)

A 1% difference in a reported percentage that would vary widely in different measurements is certainly without significance. Variations in water vapor content and variations in metabolism will produce values for exhaled air in a wider range than that. - Nunh-huh 12:00, 8 January 2018 (UTC)

Yes, even assuming Air is 21% O2 and exhaled breath is 17% O2, you are looking at a 20% difference in saturation. Healthy people at sea level normally have a 100% blood O2 saturation, but people with sleep apnea can go for significant periods with a 70% saturation. And, again, 70% or 80% is much better than zero.

There is also the recent change in CPR guidelines which changes the initial order of steps from ABC (airway, breathing, compression) to CAB, so that the first step is compression. See Dragons flight on this below. μηδείς (talk) 15:53, 8 January 2018 (UTC)

In most places the latest guidelines for CPR recommend doing only chest compressions, without the mouth-to-mouth part. See Cardiopulmonary_resuscitation#History and also here. AndrewWTaylor (talk) 08:25, 8 January 2018 (UTC)

To clarify, CPR with rescue breathing is still recommended for trained professionals (as far as I know), and is believed to be of some benefit. However, it was found that when untrained or lightly trained members of the public tried to do rescue breathing they were so often confused and/or ineffective that there was often no benefit and in some cases additional harm when compared to performing chest compressions alone. So the new recommendation is for most people attempting to do CPR to just perform chest compressions, which provides most the benefit and is less likely to confuse non-experts. Dragons flight (talk) 12:20, 8 January 2018 (UTC)

This is covered in Cardiopulmonary resuscitation#Compression only which is linked in the history sectionl and also the effectiveness section. The particular cases where rescue breaths seem to offer some benefit is for children due to the increased likelihood the cardiac arrest has a non cardiac cause, and victims of drowning or drug overdose. Nil Einne (talk) 10:52, 9 January 2018 (UTC)

Good question! We mammals have a relatively inefficient respiratory system, where a lot of work is done pulling in air just to exhale it again. This is because we use tidal respiration, where the gas flow reverses constantly–you breathe in, and then breathe out through the same pathway. Gas exchange only occurs with air that's in contact with the surface of the alveoli; the remaining "dead air" is wasted. This is why there's still plenty of oxygen in the air you exhale. The "limiting factor" in our breathing is the need to get rid of carbon dioxide, not the need to get more oxygen into the lungs. The urge to breathe is, in fact, triggered by blood carbon dioxide levels. This is why you can painlessly asphyxiate from breathing carbon monoxide or an inert gas; you're still getting rid of carbon dioxide, so your body doesn't know anything's wrong. Rebreathers also exploit the fact that exhaled air has plenty of oxygen still in it. They just remove the carbon dioxide, and recirculate the rest of the air to be breathed again. Birds have a much more efficient respiratory system, where air flows in one direction throughout, minimizing "dead air". --47.157.122.192 (talk) 10:09, 8 January 2018 (UTC)

I am reminded that the advice given to those who hyperventilate due to anxiety is to breathe the same air several times using a paper bag [1] to increase the level of carbon dioxide in the blood. The usual advice is to do it about six times: the level of oxygen is clearly safe even when the same air has gone through the system several times. Wymspen (talk) 11:26, 8 January 2018 (UTC)

By its nature, hyperventilating puts out less CO2 per breath, so we can't compare those numbers directly. Carbon dioxide poisoning happens at a few percent (see the table there). Occupational guidelines on carbon dioxide are often quite a bit stricter, though I sense a strong lobbying influence from ASHRAE to turn the top floor of every major building into an HVAC shrine. Wnt (talk) 16:20, 8 January 2018 (UTC)

The point of the whole "breathe into a paper bag" thing is to artificially increase the fraction of inspired CO2 to compensate the respiratory alkalosis caused by hyperventilition with its attendent purging of arterial CO2.

How we use burning Energy?

Anlagenwirkungsgrade vs Anlagennutzungsgrade

Ich habe gelesen, auch in Pennsylvania wird Deitsch gschprochn, ein Dialekt welcher von vielen Amish gesprochen wird. Daß die Amish aus Glaubensgründen viele der uns lieb gewonnenen "technischen" Errungenschaften konsequent ablehnen ist bekannt. Im Hinblick auf eine gewünschte Reduzierung der Kohlendioxidemissionen möchte ich mit diesem Beitrag an die Community der Amish-People die Frage stellen inwieweit die Nutzung Photoelektrischer und solarthermischer Effekte mit Ihrer Lebensphilosophie vereinbar ist. Viele Gründe sprechen dafür sich der Kraft von Sonne und Wind zu bedienen. To collect the Energy from the Sun is easy and there are different Systems available they will produce Electricity or Heat by using the Physical Way. It is not Chemistry, when we use Collectors to catch that Photons, the Sun will deliver us most of the Days in the Year. What do Amish People think about Decarbonisation and Renewables, which can they use in the Future written by Umweltheizung - 4. January 2018 to translate into the "Deitsch" writing and speaking Wikipedia-Community in USA and Canada.

Isn´t it a technical and economical Process, How we are transforming Energy into Electricity and Heat? The Efficience is less than 70% and we can do that same with enormous higher efficiency Results. Using Renewables, like the Power of Wind and the Power of the Photons we could collect a lot of Energy, and transform into Electricity and we can save this Energy easy and cheap into hot Water Storage´s.

Anlagenaufwandszahlen|Diskussion — Preceding unsigned comment added by Umweltheizung (talk • contribs) 14:35, 8 January 2018 (UTC)

The Amish, many of whom have a "Pennsylvania Dutch" heritage and may continue to use Deitsch, have a strongly organized religious community that uses shunning to maintain an unusual degree of homogeneity. A chief goal of many of their beliefs -- including resistance to electrification and gasoline power -- is actually to preserve their independence from "the English" (who have since come to call themselves Americans). As such, renewable energy is clearly very appealing to their beliefs: [2] [3] It is already not uncommon to see Amish businesses that are well equipped with power tools, doing high quality technical craftsmanship. Wnt (talk) 16:30, 8 January 2018 (UTC)

The word "Deitsch" can refer to both the people and their language. The link Deitsch is a redirect to the article on the people, the article about their language is located at Pennsylvania German language. --Jayron32 19:50, 8 January 2018 (UTC)

health effects of RF radiation

Hi, I came across a video that quotes some figures for health effects of Radio Frequency Electromagnetic radiation at various power densities. https://www.youtube.com/watch?v=QHkOdoDx-0c at 8:10. I am looking for this kind of data, which should form the basis of allowable levels of either power density or Specific Absorption Rate. I have not been able to find anything useful. Any help is appreciated. GilHamiltonTheArm (talk) 20:38, 8 January 2018 (UTC)

There is an article Electromagnetic radiation and health that may have some of what you need.

ApLundell (talk) 22:56, 8 January 2018 (UTC)

I should note that the video linked is quite the pile of batshit crazy. The gist is that electromagnetic radiation causes brain damage by interacting with "micro-antennas" delivered to the brain by mandatory vaccines. This is the level of crazy that, if this person says the sky is blue, go outside and double-check. I wouldn't take anything from the video as factual. Anyway, "health effects of radio frequency" is a very large subject. I think our article gives a decent overview, but if you have a more specific question, we could answer in better detail. Someguy1221 (talk) 01:58, 9 January 2018 (UTC)

OP: Hi again, I don't know how to make my question more specific. The level of mammalian excrement in the video is beside the point. I am looking for the data that underlies the officially determined allowable levels. There are health effects at high field strength and at high power density: I want to see the data, so I can determine whether the allowable levels make sense. GilHamiltonTheArm (talk) 08:00, 9 January 2018 (UTC)

This page of references from the U.S. Occupational Safety and Health Administration seems to have a wealth of leads to help you research the answers to your question. Here is a study from a journal called "Environmental Health Perspectives" that seems to be pretty good as well. Hope that helps some! --Jayron32 13:49, 9 January 2018 (UTC)

Generally radio frequencies do no harm, even if you stand right next to a 100 kilowatt frequency generator, which i once did on a guided tour at a public day of a big radio station. I never forget the amazing trick the guide pulled of to show us how much power was in the air: He grabbed a standard big neon lamp tube, naked without anything connected, held it near the generator and it brightly lid up. Of course he enshured us that this causes no harm, not even when you spend your working life next to it.

The miracle with frequencies is simply about when they resonate (start to affect/swing) something - in our personal safety case water. Simply put you could safely sleep inside a 100 kilowatt radio frequency generator but you can not put your hand into a 700 watt Microwave oven for more than maybe 10 seconds - best not at all, ever. Simply put because the microwave frequency resonates with water and the radio waves dont. --Kharon (talk) 17:15, 9 January 2018 (UTC)

Microwave ovens actually don't cause water molecules to resonate [4]. Someguy1221 (talk) 18:42, 9 January 2018 (UTC)