How is it that a breathalyzer can measure the alcohol content in someone’s blood, hours after they had their last drink, based on their breath alone?
Kako to da alkotest aparat može da izmeri količinu alkohola u nečijoj krvi, nekoliko sati nakon što su popili poslednje piće, samo na osnovu daha?
Exhaled breath contains trace amounts of hundreds, even thousands, of volatile organic compounds: small molecules lightweight enough to travel easily as gases. One of these is ethanol, which we consume in alcoholic drinks. It travels through the bloodstream to tiny air sacs in the lungs, passing into exhaled air at a concentration 2,000 times lower, on average, than in the blood.
Izdahnut vazduh sadrži tragove stotina, čak i hiljada, štetnih organskih jedinjenja, malih molekula dovoljno laganih da putuju lako kao gasovi. Jedan od njih je etanol, koji konzumiramo u alkoholnim pićima. Putuje kroz krvotok do malih vazdušnih kesa u plućima, prelazeći u izdahnut vazduh pri koncentraciji 2,000 puta manjoj, u proseku, nego u krvi.
When someone breathes into a breathalyzer, the ethanol in their breath passes into a reaction chamber. There, it’s converted to another molecule, called acetic acid, in a special type of reactor that produces an electric current during the reaction. The strength of the current indicates the amount of ethanol in the sample of air, and by extension in the blood.
Kada neko dune u alkotest, etanol u njihovom dahu prelazi u reakcijsku komoru. Tamo se pretvara u drugi molekul koji zovemo sirćetna kiselina, u specijalnom tipu reaktora koji proizvodi eletričnu struju tokom reakcije. Jačina struje pokazuje količinu etanola u uzorku vazduha, i po analogiji, u krvi.
In addition to the volatile organic compounds like ethanol we consume in food and drink, the biochemical processes of our cells produce many others. And when something disrupts those processes, like a disease, the collection of volatile organic compounds in the breath may change, too. So could we detect disease by analyzing a person’s breath, without using more invasive diagnostic tools like biopsies, blood draws, and radiation?
Pored isparljivih ogranskih jedinjenja kao što je etanol koje koristimo u hrani i piću, biohemijski procesi naših ćelija proizovde mnoge druge. A kad nešto prekine te procese, kao bolest što može, kolekcija isparljivih ogranskih jedinjena u dahu može da se promeni takođe. Dakle da li bismo mogli da detektujemo bolest analizirajući dah osobe, a da ne koristimo invazivnije instrumente za dijagnostiku kao što su biopsije, vađenje krvi i radijacija?
In theory, yes, but testing for disease is a lot more complicated than testing for alcohol. To identify diseases, researchers need to look at a set of tens of compounds in the breath. A given disease may cause some of these compounds to increase or decrease in concentration, while others may not change— the profile is likely to be different for every disease, and could even vary for different stages of the same disease.
U teoriji, da, ali testiranje na bolest je komplikovanije od testiranja na alkohol u krvi. Da bi se identifikovala bolest, istraživači treba da posmatraju skup od desetine jedinjenja u dahu. Određena bolest može da uzrokuje da se neka jedinjenja povećaju ili smanje u koncentraciji, dok druga mogu da budu nepromenjena, šablon je verovatno drugačiji za svaku bolest, a možda čak i varira za različite etape iste bolesti.
For example, cancers are among the most researched candidates for diagnosis through breath analysis. One of the biochemical changes many tumors cause is a large increase in an energy-generating process called glycolysis. Known as the Warburg Effect, this increase in glycolysis results in an increase of metabolites like lactate which in turn can affect a whole cascade of metabolic processes and ultimately result in altered breath composition, possibly including an increased concentration of volatile compounds such as dimethyl sulfide. But the Warburg Effect is just one potential indicator of cancerous activity, and doesn’t reveal anything about the particular type of cancer. Many more indicators are needed to make a diagnosis.
Na primer, tipovi raka su među najistraživanijim kandidatima koji mogu da se dijagnostikuju putem analize daha. Jedna od biohemijskih promena koju većina tumora uzrokuje je veliko povećanje kod procesa generisanja energije koje se zove glikoliza. Poznato kao Varburgov efekat, ovaj porast u glikolizi prouzrokuje povećanje metabolita kao što je laktat koji zauzvrat može da utiče na celu kaskadu metaboličkih procesa i naposletku rezultira promenjenim sastavom daha, verovatno uključuje povećanu koncentraciju isparljivih jedinjena kao što je dimetil-sulfid. Ali Varburgov efekat je samo jedan potencijalni indikator prisutva raka, i ne otkriva ništa o posebnom tipu raka. Mnogo više indikatora je potrebno da bi se ustanovila dijagnoza.
To find these subtle differences, researchers compare the breath of healthy people with the breath of people who suffer from a particular disease using profiles based on hundreds of breath samples. This complex analysis requires a fundamentally different, more versatile type of sensor from the alcohol breathalyzer. There are a few being developed. Some discriminate between individual compounds by observing how the compounds move through a set of electric fields. Others use an array of resistors made of different materials that each change their resistance when exposed to a certain mix of volatile organic compounds.
Kako bi našli ove subtilne razlike, istraživači upoređuju dah zdrave osobe sa dahom osobe koja pati od neke određene bolesti koristeći šablone zasnovane na uzorcima stotine dahova. Ova kompleksna analiza zahteva fundamentalno drugačiji, prilagodljiviji tip senzora u odnosu na alkotest aparat. Nekoliko njih se razvija. Neki razlikuju individualna jedinjenja tako što posmatraju kako se jedinjenja pomeraju kroz niz električnih polja. Neki drugi koriste niz otpornika napravljenih od različitih materijala gde svaki menja svoju rezistenciju kada je izložen određenoj mešavini isparljivih organskih jedinjenja.
There are other challenges too. These substances are present at incredibly low concentrations— typically just parts per billion, much lower than ethanol concentrations in the breath. Compounds’ levels may be affected by factors other than disease, including age, gender, nutrition, and lifestyle. Finally, there’s the issue of distinguishing which compounds in the sample were produced in the patient’s body and which were inhaled from the environment shortly before the test.
Postoje i drugi izazovi. Ove supstance su prisutne u veoma niskim koncentracijama, obično samo nekoliko delova u milijardi, mnogo manje nego koncentracije etanola u dahu. Na nivoe jedinjenja mogu da utiču faktori koji nisu sama bolest, uključujući godine, pol, ishranu i način života. Na kraju, postoji problem razlikovanja koja jedinjenja u uzorku su proizvedena u telu pacijenta a koja su udahnuta u okruženju neko vreme pred testiranje.
Because of these challenges, breath analysis isn’t quite ready yet. But preliminary clinical trials on lung, colon, and other cancers have had encouraging results. One day, catching cancer early might be as easy as breathing in and out.
Zbog ovih izazova, analiza daha nije skroz spremna za sada. Ali preliminarne kliničke studije na raku pluća, debelom crevu, i ostalim tipovima raka su imale ohrabrujuće rezultate. Jednog dana, rano otkrivanje raka može biti lako kao udisaj i izdisaj.