Ingestion of caustic substances is a pretty common occurrence in the U.S., usually by curious toddlers and occasionally by adults who just want to die in a horrifically painful and prolonged way. I’ve already examined a case here where a man committed suicide by downing a bunch of sulfuric acid like it was tequila on spring break. Acid substances usually have to have a pH < 2 in order to cause significant damage. In that particular case that guy drowned himself with it and it messed his guttyworks up beyond all recognition. Surprisingly, acidic substances aren’t as bad as alkali substances because your digestive tract is built to withstand the acid of your stomach up to a certain threshold. Acidic substances disrupt the covalent bonds that help keep your cell together with their excess H+ ions floating around. This results in coagulative necrosis, destroying the outermost layers of cells and causing them to slough off. Alkali substances destroy the tissue all the way through because they act like a detergent that obliterates cellular membranes and liquefies your cells, also known as liquefactive necrosis. If acidic substances need a pH<2 in order to cause substantial damage, the inverse is that an alkali substance requires a pH>11.2 to wreck stuff up, and hoo-boy does it ever.
While H+ is what makes acid so… acidy, OH- is what makes alkali so… alkali-y. OH- is pretty particular about collagen, muscle and blood vessels unlike acid. So while the OH- is smashing through the cell membranes like they’re made of glass, it also causes clots to form in the underlying blood supply, cutting the tissues off from the oxygen supply and killing them.
But wait, there’s more chemistry! Once that alkali mixes with the acidic environment that constitutes your digestive track an exothermic reaction occurs, releasing heat that further burns the tissues. All of this quick, penetrating damage can cause tissue to swell, like your airway for instance. That too is a bad thing.
So how is caustic ingestion managed? Well like most emergency situations to want to maintain the airway, breathing and circulation so they don’t die. The horrific nature of these injuries is that you have to let them take their course. You don’t want to try to dilute whatever they ingested or lavage it out because if they puke and aspirate the caustic substance into their lungs they’re likely going to die. So you have to let the caustic substance ride it out through the digestive tract till it’s tired of causing death and mayhem to cells. One thing you want to keep an eye out for is air in the thorax or abdomen because that means something was damaged so severely it ruptured. After 24 hours an esophagoscopy should be performed to assess the level of damage and check for edema or perforation. You’re also going to want to pump that patient full of antibiotics and proton pump inhibitors to reduce any further damage and complications. The biggest worry is the formation of strictures, where the damaged tissue tightens up and narrows the lumen permanently.
One way to prevent this from happening is a NG tube or stents to help keep the lumen open. If that doesn’t work, they often replace the esophagus with a piece of bowel.