One of my daughters just became an RRT after passing a practical exam demonstrating her understanding of the respiratory system and the devices and tools used to treat the lungs. She was talking about a video of someone promoting putting hydrogen peroxide solutions into nebulizers instead of approved treatments. While hydrogen peroxide solutions are used to treat the mouth in some strengths and for some conditions, they are not similarly recommended for use in the lungs. What is the main factor making the lungs so susceptible to harm when exposed to hydrogen peroxide solutions?
A. Area differences between lungs and mouth
B. Bioavailability differences between lungs and mouth
C. Catalase activity differences between lungs and mouth
D. Depth of tissue layers differences between lungs and mouth
Answer: A Notes: While not designed in humans for absorbing gases, the GI tract has evolved in some species to do a decent job of gas absorption and once you get down to the small intestines, which lots of things taken into the mouth eventually get to, the surface area is considerably larger than the mouth thanks to all of the villi and microvilli.
Also, since the blood caries oxygen they contain significant amounts of catalase to deal with the endogenous production of hydrogen peroxide. So, there's an additional barrier to hydrogen peroxide taken into the oral route making its way to other organs.
For hydrogen peroxide solutions the primary risks of ingestion tend to be injury to the lining and gas buildup in the stomach. However, apparently it is possible to cause systemic gas embolisms if a concentrated solution gets ingested.
One person accidentally drank ~50 mls of 50% hydrogen peroxide stored in a water bottle at work.
From Household Chemical to Medical Emergency: Stroke Induced by Hydrogen Peroxide Ingestion - PMC https://pmc.ncbi.nlm.nih.gov/articles/PMC11285714/
Bioavailability does not significantly differ with strong oxidizers exposed directly to mucous membranes in the digestive or respiratory systems. Catalase activity is highest in the blood due to the red blood cells transporting oxygen and their need to detoxify endogenously produced hydrogen peroxide. Both the mouth and the lungs being directly exposed to air containing ~21% oxygen have catalase activity. So does the red blood cells providing oxygen to those and other organs. However, the linings of the alveoli are very thin to allow for gas exchange. It is this limited tissue depth in the smallest parts of the lungs which makes them so much more susceptible to acute chemical damage than the much thicker linings making up the oral cavity.
Asbestos causes mesotheliomas in the lung through what mechanism?
A. Asbestos contains carcinogens (e.g., benzo(a)pyrene) that leach out leading to carcinogen
B. Asbestos only causes mesotheliomas in the gut and not the lungs
C. Large surface area of nanoparticles generates reactive oxygen species causing chronic inflammation that leads to carcinogenesis
D. Long fibers too big to be removed by macrophages get trapped in the lungs cause chronic inflammation that leads to carcinogenesis
Answer: D Notes: Asbestos is a carcinogen. Asbestos causes mesothelioma in the gut and lungs but even in cases where mesothelioma occurs in the peritoneum, inhalation is thought to be the initial route of exposure with the fibers being carried out of the lungs along with mucous or lymph. It is the length of the fibers making them too long to be carried out by a single cell leading to frustration and damage due to cellular defenses going wrong that is considered the way asbestos fibers cause cancers. The "turtles on a log" images showing many immune cells attacking a single fiber are a good visual of this process.
Which of the following is an acute response to chemical lung injury?
A. Asthma
B. Bronchiolitis obliterans
C. COPD
D. Pulmonary edema
Answer: D. Notes: Asthma, Bronchiolitis obliterans, and COPD are all chronic conditions with COPD standing for Chronic Obstructive Pulmonary Disease.
The P in P100 stands for oil-Proof while the N in N95 stands for Not resistant to oil. The 100 and the 95 refer to the efficiency of removing particles of a certain size respectively. These filters, similar to the respiratory system they are protecting, trap particles using a combination of impaction, interception and diffusion. Which of the following is going to be most dependent on impaction and interception and least dependent on diffusion at room temperature in terms of both getting trapped in the filter and if a filter is not worn, getting trapped in the lung?
A. Asbestos
B. Brodifacoum
C. Chlorine gas
D. Dichlorvos
Answer: A. Notes: These are all bad things to breathe in, but chlorine gas is the smallest in terms of size while brodifacoum and dichlorvos are rodenticide and insecticide small molecule biocides respectively. Asbestosis is encountered as a mineral in its friable form and as such is most dependent on impaction and interception.
Cases of a kind of severe lung damage called bronchiolitis obliterans have been associated with the presence of tocopherol acetate particularly as part of THC vaping liquids. This kind of lung damage has also been associated with occupational exposures to what other chemical?
A. Avocado oil
B. Brewer's yeast
C. Capsaicin (chili spice)
D. Diacetyl (buttery popcorn flavoring)
Answer: D. Notes: Oil, even vegetable oil, can cause lipid pneumonia if it gets into the lungs. This can occur through aspiration but can also occur through inhalation through occupational exposures (e.g., cutting oil, cooking oil). Brewer's yeast when aerosolized can cause yeast infections in the lungs or even in cuts in the skin. Capsaicin causes immediate irritation to mucous membranes and can cause breathing difficulties if inhaled. But it is the use of diacetyl in butter popcorn flavoring that led to bronchiolitis obliterans also being called, "popcorn lung." If you're ever in a position where you have to help answer questions for a company's annual insurance assessments, like me you may even have to answer questions about the risk of worker exposure to diacetyl.
