Nauseating Evidence Part 3/3 (Isopropyl Inhalation)
My first clinical ride-along with the local Fire Department was a cardiac arrest. As we walked into the room, we quickly hit a wall of foul odor. The patient had clearly defecated all over the floor, exactly where we would be kneeling to do CPR. A kitchen rug was placed down beside where I would be positioned when doing compressions.
As I started performing compressions for the first time in my career, a wave of nausea overtook me. I looked at one of the paramedics applying the defibrillator pads and gave a quick nod of my head. I wanted to assure him that even though I probably was turning green in the face, I was fine. It was only seconds later I felt a gloved finger rub something on my upper-lip. A pat on my back and quick visual of a Vick's bottle, correlated what they had done.
"We carry a bottle of this to help with foul smells in the field," said the lead paramedic.
Within just a few seconds, I felt almost complete relief from any nausea. Throughout my career, I have noticed that alcohol prep's had the same effect when presented with foul-smelling assignments, long trips in the back of the ambulance, or even nausea from a virus. It is hard to tell if the mechanism behind this is legit or perceived. Regardless, it seemed to help. The mind is a powerful thing.
I personally have always chalked the mechanism of action behind this to olfactory distraction. It appears that the nose is somewhat ADHD when it comes to smells.
There has been relatively recent amounts of attention to the use of Isopropyl inhalation to treat nausea in the emergency department and transport setting. However, the benefits of this intervention were only analyzed in post-operative management of nausea. The most common reason for post-operative nausea, is the sedative agent effects on the chemoreceptor trigger zone (CTZ).
Passing The Sniff Test
In July of 2016, the Annals of Emergency Medicine published the first ever RCT comparing inhaled Isopropyl vs. inhaled saline, for the treatment of all comer emergency department nausea. They used a verbal-numerical score of 0-10 (like the one we use for pain) to quantitate a value for inclusion. The patient had to have rated their nausea greater than a three to be considered for the study.
... It Actually Works!
The results were impressive. The intervention arm had a three-point reduction in nausea with improved satisfaction. This was a statistically significant outcome that further validated the hypothesis. There were several limitations to this study that you probably are already considering.
Isopropyl Clearly Smells Different Than Saline
It is difficult to conceal an intervention with a distinct smell. The investigators would instruct the patients included in the study, to not verbalize any information about the smell. If the patient was unable to open the packaging of the concealed pad, the investigators were instructed to open the package at an arm's length to avoid smell identification. Even though there was a good technique to avoid investigator bias, the patient's in the intervention arm would most likely be able to identify the smell of Isopropyl. The control arm, however, would probably not be clued into the fact that they were inhaling saline. If a Hawthorne effect were to take place in either group, it would need to of been apparent in the control arm as well. This did not seem to artificially cure their perception of nausea in the control group.
Did The Nausea Come Back After 10 Minutes?
This study looked at nausea at 10 minutes after the intervention. There is a chance the symptom relief could have been short-lived. Because of the short 10 minute window of evaluation, adverse side effects outside of this parameter would have not been documented as well. Chart review did show no clinical deaths or complications were documented within both arms.
My conclusion... it's sure worth a shot. This intervention appears to be cheap, safe, and effective. Here is how I plan on executing it.
Step 1- Tear off the top portion of the alcohol prep, so that it makes a pouch containing the pad. Leaving it in the pack appears to trap in the scent and allow a more concentrated "whiff." This is purely anecdotal. This study does not describe whether the pad was removed or kept in the pack.
Step 2- Instruct the patient to inhale the packet for about 10 seconds... exhale.... and then do it again. You will perform this 3 times. The study mentions that the patients were instructed to inhale no longer than 30 seconds. It appears 10 seconds is as long as I can inhale without reaching vital capacity... I'm a wimp.
The concentration appears to dilute after a few minutes. For this reason, I suggest waiting to the patient is completely ready and instructed on the steps before opening the package.
Further Reading: Oral Ondansetron compared with Isopropyl inhalation.
All references are hyperlinked throughout the blog.