Filipe Marchesini's Shortform 2020-04-29T13:38:19.597Z · score: 2 (1 votes)
Looking for a Team to Participate on a Competition 2020-04-14T12:29:48.769Z · score: 3 (2 votes)
Hydroxychloroquine: the day science stopped 2020-04-05T18:09:58.290Z · score: 21 (8 votes)
What is the appropriate way to communicate that we are experiencing a pandemic? 2020-03-04T00:02:01.879Z · score: 14 (6 votes)


Comment by filipe-marchesini on Collection of GPT-3 results · 2020-07-20T13:36:09.517Z · score: 1 (1 votes) · LW · GW

Did you pay the premium version? I am using the free version and I am not sure if the free version is GPT-2 or GPT-3.

Comment by filipe-marchesini on Erving Goffman’s ‘paper’ · 2020-07-18T07:55:38.037Z · score: 1 (1 votes) · LW · GW

Welcome Saffron!

Comment by filipe-marchesini on Calibrate words, not just probabilities · 2020-07-18T07:16:28.990Z · score: 2 (2 votes) · LW · GW

Most babble that seems to be "predictions" are actually not predictions and, as pointed by Ericf, they do not reflect the internal confidence of the speaker. Sometimes I hear "I am completely sure my favorite team is going to win the championship", although it is clear that this is not a prediction made by the person, it is his way of saying "I really would like this outcome to happen and that's my way of signal this".

"He is not going to die" doesn't mean "I predict with 90% confidence that he is not going to die" but rather "I wouldn't like him to die, and even though the unknown real probability may be high, just accepting this may create this reality, so I will say he is not going to die and reality will follow my words, and that's the power of words, as god said on the bible".

I really see a lot of people talking about "the power of words", so they don't try to truly have accurate beliefs that predict accurately the results on some timestamps, but just uttering the words "may alter reality in a way that they don't like", so they just pretend to be high confident on some possible good outcomes because, well, "I am absolutely sure coronavirus will not be that bad", but hey, "although it was very bad, I am sure everything is going to be fine". Hey, I am sure we will handle the situation and that there will still be some beds on the hospital for people. Why these fucking words don't work? Your partner says: don't give up, I am sure everything is going to be fine.

After all, if Freddy Forecaster says "70% probability" for events that happen only 60% of the time, I know to correct, in mind, Freddy's forecast- when he says 70%, I know to anticipate that it will actually happen only 60% of the time, and would bet accordingly. So if Peter Pundit says something "certainly" will happen 100 times, and we see 55 of these events actually happen, the next time he says something "certainly" will happen, I would be willing to bet based on his words suggesting a 55% probability.

I agree with you that we should try our best to give our best estimates, and also say our confidence in our estimates, while also creating our historic record of predictions for everyone to calibrate their confidence in our statements. But, for real, every time I see a new pundit, probably this will be the first and also the last time we will be hearing about him. It is hard to have any history of his predictions. It will be very hard to find 100 predictions registered on a platform, and count how many he got it right. And even if such a platform existed with all historic predictions, that also could be gamified in a certain way, e.g, it is easy to predict that the sun will come up tomorrow, and I will win everytime I bet on this. After winning 100/100, I try to predict the price of Tesla shares on the next day. Well, even if you used my history of random easy predictions to calibrate your confidence on my hard predictions, that wouldn't help. Idk, for me it is just ABSOLUTELY hard to calibrate my confidence on the pundits' statements even if he had put "70%" on the middle of the sentence. Probably he doesn't even know what he is talking about. And probably we won't ever have any opportunity to make him to pay rent in anticipated experiences, nor to check any previous hard predictions.

Comment by filipe-marchesini on April Fools: Announcing LessWrong 3.0 – Now in VR! · 2020-07-18T06:28:37.248Z · score: 3 (2 votes) · LW · GW

Very interesting. When I stopped teaching in person due to pandemics, I started to research the best platform to teach online. When I saw this post comparing the options, and then looked YouTube videos using each one, I became absolutely religious after testing Mozilla Hubs, and started shouting out for all directions that this thing is completely awesome and I was all in. Today, I use this platform every week. The students love it! And now I discovered LessWrong is using it too. It couldn't be different.

Comment by filipe-marchesini on Null-boxing Newcomb’s Problem · 2020-07-13T21:09:27.403Z · score: 7 (5 votes) · LW · GW




The statue became motionless again. Maxwell donates the prize to the priests who promised him salvation, for they had always been right.

Comment by filipe-marchesini on What problem would you like to see Reinforcement Learning applied to? · 2020-07-08T16:57:33.147Z · score: 5 (4 votes) · LW · GW

Problem: Automatic planting

Action space: the agent obtains data from the sensors and decides how to use the actuators (temperature modifiers, humidity, exposure to sunlight/other modifier) to maximize specific crop characteristics

The reward: the agent knows that he is performing better when he minimizes the time needed for the plants to reach specific characteristics. For example, when trying to minimize the time required for three plants to reach a specific height of 0.2m, a higher score would be attributed to the action policy that led the plant to grow faster to (0.02, 0.05, 0.10, 0.15, 0.20)m. Or say a watermelon plantation, the policy of mapping conditions of temperature, humidity (etc) that led to the emergence of the largest watermelon (given a threshold) in the shortest time possible would reward the agent with higher scores.

If it is possible to achieve high efficiency on food production using RL agents that control cheap sensors on a simple wooden box and cheap products (earth, seeds, water), we could mass produce boxes and distribute them with the embedded agent and a few rules to the final user. Users with this system would get enough food that would pay the cost of the system itself. Users could buy more boxes by selling the exceeding food, and they could distribute the boxes with neighbours, providing substantial positive impact on the world.

I really believe we should decentralize food production and it would be easier with low cost systems that automate practically the whole process, and the user would just do easy things. People would get healthier foods, they would spend less money on food (leaving more money to invest in other needs), they would develop less diseases associated with the consumption of high industrialized products or products with high amount of herbicides.

Comment by filipe-marchesini on Thoughts as open tabs · 2020-06-29T17:25:57.325Z · score: 2 (2 votes) · LW · GW

One thing I tried was keeping open tabs infinitely, and I would just close them when I had finished the work on them. Sometimes I have 40 tabs opened, and I feel the pressure to "stop opening new tabs and finish those that are already open". And then, I click on them one by one, sometimes realizing that I already did what should be done and closing them. Sometimes, I keep postponing. After a new check, I think there are tabs that don't add too much and I close them.

When you keep your tabs on mind, but not on the browser (e.g. chromium) you'll eventually lose the state of mind that you had. So I would say to you write the thought, even if it is just a summary, so you can't lose what you were thinking. Write it down, and check it later.

Comment by filipe-marchesini on Open & Welcome Thread - June 2020 · 2020-06-13T13:46:28.184Z · score: 1 (1 votes) · LW · GW

I think you are referring to Goodheart's law, because all the measures your examples used as a proxy to achieve some goal were gamified in a way that the proxy stopped working reliably.

Comment by filipe-marchesini on 2020 LessWrong Demographics Survey · 2020-06-12T13:07:51.862Z · score: 1 (1 votes) · LW · GW

Exactly, I am from Brazil and I can't see any option that fit my race.

According to Wikipedia, "According to the American census, the Hispanic or Latin category would not include Brazilians or Americans with origins in Brazil, [3] [4] [8] as it is specific to people of "Spanish culture or origin". [3] [4]. Technically speaking, people from Portugal or of Portuguese origin are called Lusitanians. In Portugal, the term "hispanic" refers to something related to ancient Hispania, Spain or the Spanish language and culture [9]. The common modern term for identifying both Portuguese and Spanish cultures under a single nomenclature is "Iberian", and the term referring to cultures derived from both countries in the Americas is "Ibero-American". These designations can be mutually recognized by people in Portugal and Brazil, in contrast to "Hispanic", which is totally devoid of any self-identification in these countries, and quite the contrary, is used to mark a clear distinction in relation to the culture of neighboring Spanish-speaking countries (Hispanics) in relation to Portuguese-speaking countries (Portuguese-speaking)."

Comment by filipe-marchesini on Open & Welcome Thread - June 2020 · 2020-06-09T21:32:39.239Z · score: 7 (4 votes) · LW · GW

I think you can refer the person to orthogonality thesis

Comment by filipe-marchesini on Open & Welcome Thread - June 2020 · 2020-06-03T10:58:46.386Z · score: 34 (16 votes) · LW · GW

LessWrong warned me two months before it occurred here. The suggested preparedness was clear and concise, and I felt the power on my hands. I had valuable info no one on my tribe had. I alarmed my mom and she listened me, stayed home and safe, when everyone was partying out (carnival). I long-talked with friends, and explained to them what I believed it was happening and why I believed that. I showed the numbers, the math, the predictions to the next week, next week came, and reality presented its metallic taste. Week after week, the light was getting brighter and brigher until it turned really hard to refuse to see it, or to believe on the belief that everything was just fine.

One thing I learned is that it doesn't matter if you just know something really valuable, but can't convince those that do matter for you. I tried to explain my 50 years experienced physician father that he should listen to me. He blamed my low status. But even after weeks, police at the streets forcing citizens to stay at home, he could not believe. He was in denial and my incompetence to change his mind made him to the hospital, 16 days and he isn't still back. Don't worry, he is getting better and I am just babbling around. Father of a cousin died. Brother tested positive. Stepmother obviously got it too, but tested negative. You know, I really tried, not just tried to try, not even planned to try, I really did it right way. Successive failures. It wasn't enough. I don't have anything valuable to share more than 'you have to learn ways of convincing your most loved ones' urgently, if you don't have this tool, but I don't know how to do it yet, I am struggling to find a way, and I would ask you to share when you get one. Things as simple as "there is food over there" or "there is a lion coming to you", on level 1 talk. Maybe the dark arts could have helped me when level 1 failed, but not sure. But I feel very happy for a lot of peers I helped along the way, and all is due to LessWrong, I am thankful for this community, and I changed the behavior of some people I know on the right moment of the outbreak. This simple text forum saves many lives and I am on the path to contribute too on larger scale.

I know I am not that new on the forum, I don't remember exactly when I started here, but I believe it was on the last months of the last year, but I still think I am noob, but learning. Don't upvote this comment, but do comment if you wanna say something.

Comment by filipe-marchesini on What aspects of the world emotionally bothers you on an immediate personal level on a daily basis? · 2020-05-24T11:00:16.501Z · score: 11 (9 votes) · LW · GW

The people on my personal circle I like the most don't know basic math and are not interested in learning anything about it.

I can't talk with relatives about optimizing anything, because mostly they don't allow me to talk. When I do talk, they don't listen anything. For them, the game is just about status. Or politics. Trash talk all the time. Nothing objective. As time goes on, I talk less and less with them. I don't see any solution for this, and I feel guilty for thinking on giving up on trying to express my thoughts for them.

I feel bad about realizing I killed animals and ate their corpses my whole life. And this is considered the norm, and my family can make me feel bad for even considering not murdering more non-human animals. I feel bad the most of the world don't care about non-human animals.

I feel bad for not being able to buy for my mom a house that does not flood every rain that has been happening daily.

Comment by filipe-marchesini on On Negative Feedback and Simulacra · 2020-05-04T18:44:14.522Z · score: 2 (3 votes) · LW · GW

Hot sauce:

"[...] insults her cooking and insinuates that she doesn’t know how to cook"

If my girlfriend had said something like that, I think an appropriate solution would be:

[curious] what you mean... [\curious]. [surprised] AHHHH, the hot sauce?? [\surprised]. [empathy] Ohhh, my love. Really sorry for that [\empathy]. [confession ~ lower speaking] I have to tell you something. I am so addicted to hot sauce that I even didn't remember that I shouldn't use it in (clearly exaggerating) every meal I eat. Your meal is [emphasis] really amazing [\emphasis] and I didn't want to make you feel bad. This action of putting hot sauce was completely automatic (this conveys that I wasn't carefully choosing my actions, I was just acting by default), because I am very used to put this thing on quite every meal, I swear this isn't a special occasion. Sorry me for that, next time I won't use it and I will really try to appreciate the meal without it. It isn't even healthy to put this thing on every meal. Thanks for remembering me that.

Thinking again about it, if my girlfriend had said that, she wouldn't be trying to signal that I was insulting her cooking, but she would be trying to signal that I should praise her food. I think the guy on the post wasn't praising from the beginning. For example, once I get the first mouthful, I should already say "woooww, this is delicious". Then if I proceeded to put hot sauce, she wouldn't simply say "you are insulting me", but maybe she would assert "are you really liking the food? I see you are putting extra condiments", then I would reply, "no, this is really delicious. I am putting the hot sauce because I am addicted to it, but if you find this bad, I won't put it anymore. I really would like to leave this addiction."

Anyway I really like your posts Zvi and I would like to see more thoughts of yours here on Lesswrong. I see you carefully making your steps and I admire and learn from that.

Sorry for not exploring more on the other points of the post. Time is out, bye and thanks

Comment by filipe-marchesini on FB/Discord Style Reacts · 2020-05-04T08:33:13.514Z · score: 1 (1 votes) · LW · GW

"I was reading your post, but suddenly I had to leave in the middle of it. I would like to say that I agree/liked your intuition (to the point that I read it), and I would like to signal this immediately, because I'm afraid I won't remember to finish the reading in the future, although I would like myself to finish it in the future."

"Although your post seemed to be going in a direction I like, I had to abandon the reading. Forgive me for leaving it and not finishing absorbing a seemingly important message. I hope this reaction helps you, I'm out of time to explain why I would like to help you, bye"

"That sounds like something someone from my tribe would say. Then you seem to be an ally."

"There's only one part of your message that seems to be important."

"I'll hit like, because you quoted 'the super important thing'. Although I've seen a lot of irrelevant information in your post, I'm short of time to comment and say which part is important and which part is not. This reaction represents that 'there is an important thing in your post' and 'this thing' is the 'super important thing'."

Comment by filipe-marchesini on Peter's COVID Consolidated Brief - 29 Apr · 2020-04-29T20:00:59.961Z · score: 6 (4 votes) · LW · GW

Thanks for the great effort for bringing a summary that really makes me feel I don't have to continue digging for new information. If this work is going to be continued, I will just wait for your new updates, and then finish looking for local news, as things on my country are largely different from yours. Keep it up!

Comment by filipe-marchesini on ESRogs's Shortform · 2020-04-29T19:02:54.299Z · score: 3 (2 votes) · LW · GW

Got it. I wonder why there aren't discussions about cryptocurrencies here on LW. Like, extensively researching the existing protocols and their characteristics and then naming which one is the best and why, and betting on it. Or even using it on the forum. I would suggest you to research these two cryptos I have cited if you are interested on updating your bets.

Comment by filipe-marchesini on ESRogs's Shortform · 2020-04-29T16:52:12.093Z · score: 1 (1 votes) · LW · GW
35% crypto -- XTZ, BTC, and ETH (and small amounts of LTC, XRP, and BCH)

Why do you bet on cryptos with weak fundamentals like LTC, XRP, and BCH, and not on cryptos with stronger fundamentals like Monero and Nano?

Comment by filipe-marchesini on Prospecting for Conceptual Holes · 2020-04-29T16:01:09.779Z · score: 2 (2 votes) · LW · GW

These points really make me update my beliefs on the importance of learning Chinese. Thanks for that.

What am I missing by not speaking Portuguese?

Brazilian speaks with the body, so you are not missing that much. Haha just kidding (although it's true that body language plays a big role here). But there are 250 million total portuguese speakers, and by just knowing Portuguese you will understand Spanish easily, because there is 89% of lexical similarity. I can understand Spanish with no problems and I never studied it. If you know how to search, there is a vast and extensive Brazilian music that you wouldn't like to miss. The literature written in Portuguese remains untranslated, except for very few authors, so you would be able to read very good books (if you like certain genres). Also, Brazil is about half of South America, and is a fantastically interesting place to travel. When new people come here, the reception is warm. Music, cooking, sports and memes here are a real thing. Knowing Portuguese would make you able to connect with our culture and you would be able to access very good content on a lot of subjects. But I am fully biased and mostly looking into the bubble (mathematics, physics and computation) and you don't lose much by just using English sources for these subjects.

For example, this channel is specialized in non verbal behavior analysis and I never found anything better than that on any language. This channel is the best on musical content (how to play drums, guitar, acoustic guitar, etc, how to sing, compose, etc). This on comedy, this on history and science. I mean, if you keep looking, you will always find a lot of good content on very different subjects. You will miss all of this by not knowing Portuguese, as with any language.

If you look on the science side, you can check Brazil here (tables from page 4~9).

There is no good translator from Portuguese to any language yet, and your best tool to date would be DeepL, in case you need to translate Portuguese info to English.

Comment by filipe-marchesini on Filipe Marchesini's Shortform · 2020-04-29T13:38:19.899Z · score: 1 (1 votes) · LW · GW

Suppose a dynamic in which a creator announces that wants to complete a task. E.g.:

Creator: "I would like to give a lesson teaching how to remove the background of a photo".

The creator optionally puts a threshold in which, once the users already demonstrated enough interest, the creator starts streaming his job. Let's suppose, e.g., that the last creator have put the threshold: "$50.00".

Users decide to "put money on the table" on the platform, signaling interest in seeing the creator accomplishing the task.

Users can also signal interest without putting money on the table. The conventional "Like system". The creator can also put a threshold on the number of likes he would be willing to create the content.

Suppose during an hour these users demonstrated interest:

Users_and_values = {User1: $0.50; User2: $2.50; User3: $1.50; User4: $0.25; User5: $0.00004522; ... ; UserN: $0.10}

Once the sum(Users_and_values.values()) == 50 (it hits the threshold), the platform signal to the creator that there are enough users willing to pay for his content.

The creator starts streaming what he promised he would do (all registered users on the creator channel receive notification messages). During the stream, the users that had showed interest (and those that hadn't too) in paying can pay any time, any amount of what has been promised. For example, once the streamer already have accomplished 50% of what he promised (and signal that), users could decide to pay 50% of what they promised. "Paying as he goes" would be very cool and it would have a bar being automatically updated showing the amount already collected by the creator during the stream. If the job is not good or it is not like what has been promised by the creator, users can simply not pay. Users could simply pay 100% of what they said they were willing to pay once the streaming ends. I think you get the idea. If not, let me know if this is not clear.


Users can not show willingness to pay more than what they have on their wallet;

If a user says he is willing to pay $1.00 for seeing a task accomplished by a creator and the user didn't pay anything after the creator accomplished his job, the user should justify why. If he doesn't justify, his karma will be lowered and the next time he promises to pay $1.00, the amount would be multiplied by the probability of he paying.

There should be a threshold on maximum willingness to pay. Otherwise, an user with $1,000,000 could just show fake willingness to pay for all creators.

The payments would occur using the digital currency NANO, that allows free and instant transactions. I would like to see your input on the general idea, there are several details not discussed yet.

For instance, this could be used to reward LessWrong creators for creating their posts. Or even noobs like me would be willing to try more crazy ideas just because there are enough money on the game. Normally, I wouldn't randomly "create a sale system for bakeries". But if people suddenly said they would pay $50 bucks for seeing me doing that, that's a completely new story.

Users could also create their posts requesting what they want:

Eliezer: "Suppose you underwent a low-risk Corona exposure situation, but you very much want to avoid infecting a pool of friends or housemates. Is there a 50/20 (if maybe not 80/20) on quarantining yourself away during the time when you are most likely to be (quite?) contagious without having developed symptoms? [...] $500 for a definitive response of this kind with citations. "

So Eliezer creates the post, and puts the money. Users start submitting their answers to the post, and whenever Eliezer sees a satisfying solution, he simply clicks on "reward user".

If Eliezer never pays anyone on a sucession of posts and without justification, he could have his karma lowered. Users could report other people that are creating baits

Comment by filipe-marchesini on Prospecting for Conceptual Holes · 2020-04-29T08:56:21.174Z · score: 6 (2 votes) · LW · GW

Learning a new language (English) was decisive in my life to fill a lot of type 1, type 2 and 3 holes as you presented on this post.

In 2013 "I felt" I should learn English. I didn't have a clear goal on doing it, but "it seemed important on the long-term", but I couldn't explain why it would be important to care about really learn another language.

In 2016 I heard from a YouTuber from my country talking about AI. My goals changed completely, and I could only find real quality discussions about AI or state-of-the-art information in English.

Then it came programming, blockchain, decision theory, etc, etc. Subjects that I only started caring because I learned English and found really good English content about these subjects.

This post makes me wonder what would happen if suddenly I started to learn Chinese.

Comment by filipe-marchesini on Seeking opinions on the pros and cons of various telepresence tools · 2020-04-05T22:25:20.121Z · score: 3 (2 votes) · LW · GW

Are you aware or worried about reported Zoom privacy and security issues?

Comment by filipe-marchesini on Hydroxychloroquine: the day science stopped · 2020-04-05T19:58:01.022Z · score: 1 (1 votes) · LW · GW

Thanks, corrected it now.

Comment by filipe-marchesini on How strong is the evidence for hydroxychloroquine? · 2020-04-05T18:35:35.562Z · score: 5 (4 votes) · LW · GW

Gautret et al. 2020° shouldn't be considered a study of hydroxychloroquine efficacy. It should be considered a failed attempt at studying hydroxychloroquine efficacy. Here is why I believe that.

Comment by filipe-marchesini on Welcome to Less Wrong! · 2020-03-11T09:27:17.935Z · score: 16 (6 votes) · LW · GW

WHO I AM: I have 24 years of existence. I give math, chemistry and physics lessons to high school students since 17. I am pretty good at it and I never announced anywhere on planet that I give lessons - all new students appear from recommendations from older students. On the end of 2016 I already had 38 months going to the university, trying to get mechanical engineering credentials. I wasn't interested on the course - I really liked the math and the subjects, but the teachers sucked and the experience was, in general, terrible. I hated my life and was doing it just to look good for my parents - always loved arts and I study classical music since 14. I heard about "artificial intelligence" just once, and I decided all my actions in life should be towards automate the process of learning. I started a MIT Python course and then dropped out university. I am completely passionate about learning.

WHAT I'M DOING: (short-term) I am currently learning and doing beautiful animations with the python library called MANIM (Mathematical ANIMations). I am searching for people to unite forces to transform tens of posts in The Sequences into video content with this library. I hope to gather money from it and spread rationality in general, turning it more popular. My family and my best friends have shit quality life and I would like to get enough money to change that. Most of my reasoning is "explore the solution space and find the best ways to help most people, if you really help and it is something scalable, you will get money on the way". If I get the money (instrumental goal), I will help those who need (relatives and close friends). As soon as I achieve this goal, I will jump to my long-term goals on helping ending disease, extending life (first) then killing unwanted death, refining art, playing games.

HOW I FOUND YOU: I googled "pascal wager artificial intelligence" after seeing a Robert Miles (AI researcher) video. Then I found Roko's basilisk, read a lot about it and had a bad week. Then I found Eliezer Yudkowsky talking about it, and my fear went away. Then I discovered this forum and it turned out to be my main source of truth-seeking. I don't know personally anyone who has access to this kind of source of information (Lesswrong), collective truth-seeking with strong grounds.

I VALUE: I value people who works towards making the life of others better. I value people who really seeks truth. I value people who takes ethical problems seriously. I value people who spends more than 5 minutes by the clock looking for better solutions for our everyday problems.

TO ACHIEVE WHAT I VALUE: To make the life of others better, I am daily trying to discover how can I use the programming knowledge I am acquiring daily about blockchain, artificial intelligence and mobile/web/software development to create real solutions for real problems - solutions for drinking water, food (automate prodution/distribution), education (for all ages), energy, housing, income, health and environment. I didn't develop a scalable solution for any of these problems, because I am still learning and it is very hard, I admit, but I will help, no matter what, and if you wanna lose, just bet against me. I just need a little more time.

Comment by filipe-marchesini on Coronavirus: Justified Practical Advice Thread · 2020-03-06T05:31:12.239Z · score: 5 (4 votes) · LW · GW

Thanks for the suggestion, ESRogs. I'm adding the shortened version now.

Comment by filipe-marchesini on Coronavirus: Justified Practical Advice Thread · 2020-03-04T02:45:10.655Z · score: 36 (14 votes) · LW · GW

TL;DR. If you have (slightly) low PaO2, but no trouble breathing, you probably don't need to go to the hospital. And if you have trouble breathing, you should probably go to the hospital whether or not you have low PaO2. So testing for oxygen saturation doesn't add much.

I had an online conversation with an intensive care physician. I sent him a translated version of juliawise's text and he said he didn't think buying the pulse oximeter would help and then sent me a 5 minute audio explaining why. The following text is his audio translated from Portuguese to English, I hope there are no wrong translations and I changed my mind after listening to him. Please also share what you think about his response:

"All pneumonia will desaturate the patient. O2 saturation is related to perfusion (gas exchange). Patient with acute respiratory syndrome (inflammation of the lungs by viral or bacterial infection) may course with poor tissue perfusion, that is, inadequate tissue oxygenation. One way to evaluate this is pulse oximetry, PaO2.

Patients with respiratory discomfort due to lung inflammation may or may not present desaturation. PaO2 < 90 indicates oxygen therapy. But perfusion and ARDS severity should be evaluated by the PaO2/FiO2 ratio (serum O2 concentration/offered amount of O2) to maintain good oxygenation.

What takes the patient to the emergency room is not the oxygen saturation level. You won't see a patient say "I'm feeling bad, let me see my saturation level" and suddenly find 80 or 85. If you start running and put the oximeter on your finger you can easily find 91~92.

What takes the patient to the emergency room is respiratory distress. He will feel shortness of breath and we will evaluate this with the methods of severity assessment, which would be oxygen saturation. And we would see in more severe patients a value below 90%.

The clinical picture of pneumonia is coughing, shortness of breath, respiratory discomfort, pain and by doing an x-ray he will detect a pulmonary opacity. You'll see a white field, where there should be air, there'll be fluid. Then you diagnose pneumonia.

The medical reasoning is this: I think about pneumonia based on the symptoms, I observe the saturation and it correlates with pneumonia, I see the x-ray and it correlates with pneumonia so I start the protocol... actually when I do the physical exam and I think "ah, it's an acute respiratory distress syndrome" I don't even want to know what it is initially, I want to offer oxygen, guarantee the airways, improve the gas exchange and keep the patient alive until finally I can test for coronavirus.

In fact, the saturation will indicate a marker of severity in a dyspneic patient. Not a diagnostic marker. There is no way to observe a patient who is desaturating and give a diagnosis for coronavirus.

Many things change oxygen saturation. Like I told you, oxygen saturation measures the amount of oxygen inside the RBC, right? So if I have a RBC with low hemoglobin inside, like with an anemic patient, it changes the oxygen saturation. If the patient is not doing good gas exchange, it changes the oxygen saturation. For example, lowering of consciousness will give low saturation. Also if he is shocked, hypotensive or hypothermic. Another thing that also changes is the use of enamel on his fingers. "

Then I sent him an audio saying:

Me: "I got it. But let's suppose we were in the following situation: there are 10,000 infected in the city, the government starts to declare quarantine. Suppose you're home with a fever and another symptom like cough. You're left wondering, "Should I go to the hospital and test for coronavirus?" But knowing there is an outbreak and that the hospital is crowded with people with the disease, chances are you will get the disease when you go to the hospital if you don't have it. I am at home, isolated because I have the symptoms of the disease, but I am not sure if I have coronavirus and I do not know if I should really go to the hospital. How do I know if I should really go to the hospital? Should I wait until a respiratory problem like difficulty to breathe starts to appear? Is it possible that I take the measurement with the oximeter and it gives a low oxygen saturation before I even start having a breathing difficulty?

He: "Not under normal conditions. Under normal conditions, a patient with only a cough, fever, runny nose, or an upper airway condition will not change oxygen saturation. That wouldn't make you think about going to the hospital, you'd stay home, like you did every time you had a common flu picture.

Even because you will not change the treatment. You will be treated as supportive therapy like all viral infections: H1N1, etc. But if you stay home without any signs of severity, it will resolve as if nothing had happened and the diagnosis would not be closed, you know? It would be a syndromic diagnosis... a flu picture, a common flu without any complications. What happens is that in the face of the epidemic, people are testing coronavirus for patients with acute respiratory syndrome, respiratory discomfort. Then, for fear of serious evolution, these patients are tested [for coronavirus] for early ventilatory support."

Then I sent him this text message:

Me: "1) Fever → coughs → respiratory discomfort → recommend going to hospital to test for ncov and receive early ventilatory support.

Would the mistake in my reasoning be to assume that there would be low oxygen saturation before even presenting respiratory discomfort?"

He: "Yes."

Thinking about it, now I believe if I have Fever → coughs → respiratory discomfort or shortness of breath → I should go to the hospital.

If I have Fever → coughs → NO respiratory discomfort and NO shortness of breath → check oxymeter and low PaO2 → Do not go to the hospital.

So having the oxymeter wouldn't make me go to the hospital. So I don't need an oxymeter.

Comment by filipe-marchesini on Coronavirus: Justified Practical Advice Thread · 2020-03-04T01:16:14.023Z · score: 1 (1 votes) · LW · GW

Should I expect a faster infection rate on my country (Brazil) because most people here use paper money to make trades? Should I recommend people to stop using paper money and instead opt for a contactless card? Most people don't have access to banking services; so is there any option for them?