Can a Placebo Smell Like Nothing? A Critical Appraisal of a Randomized Trial Comparing Inhaled Isopropyl Alcohol With Oral Ondansetron
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RN to BSN Program, Aspen University
N494: Essentials of Nursing Research
Instructor Name
Month Day, Year
Can a Placebo Smell Like Nothing? A Critical Appraisal of a Randomized Trial Comparing Inhaled Isopropyl Alcohol With Oral Ondansetron
Critical appraisal asks three questions of a study: are the results valid, what are the results, and will they help in caring for my patients (Melnyk & Fineout-Overholt, 2023). This paper applies those questions to a randomized controlled trial retrieved in the literature search for the Module 1 clinical question, which asks whether inhaled isopropyl alcohol relieves nausea in emergency department adults faster than oral ondansetron or placebo within half an hour. The trial, by April et al. (2018), compared inhaled isopropyl alcohol with oral ondansetron in 122 adult emergency department patients.
Study Overview and Level of Evidence
The study is a randomized, blinded, placebo-controlled trial conducted in the emergency department of an urban tertiary care hospital. Adults with nausea or vomiting who did not need immediate intravenous access were randomly assigned to one of three arms: inhaled isopropyl alcohol plus 4 mg oral ondansetron, inhaled isopropyl alcohol plus an oral placebo, or inhaled saline placebo plus 4 mg oral ondansetron. The primary outcome was the change in nausea on a 0 to 100 mm visual analog scale from enrollment to 30 minutes. Secondary outcomes were the use of rescue antiemetic medication and adverse events (April et al., 2018).
As a single randomized controlled trial, the study represents Level II evidence in a common hierarchy, below systematic reviews of randomized trials and above nonrandomized and observational designs (Melnyk & Fineout-Overholt, 2023). Its design is well suited to an intervention question because randomization, when done well, balances known and unknown factors between groups, so differences in outcome can be attributed to the intervention.
Are the Results Valid?
Several features support validity. Participants were randomized, the trial used placebos to allow blinding, and follow-up was nearly complete: 120 of 122 enrolled participants (98.3 percent) finished the study, so attrition is unlikely to have biased the results (April et al., 2018). The outcome measure, a visual analog scale for nausea, is widely used and has been validated for this purpose, and the 30-minute time point matches the clinical need for rapid relief.
Other features limit confidence. Participants were a convenience sample enrolled when research staff were available, which may not represent all patients who present with nausea. The study took place at a single center, and patients who needed intravenous access were excluded, so the findings apply to less severely ill patients. The most important concern is blinding. Isopropyl alcohol has a distinctive smell, while inhaled saline has none, so participants could likely tell which inhaled treatment they received. When patients can guess their assignment, a subjective outcome such as nausea severity is vulnerable to expectation effects, and the design cannot fully separate the effect of the alcohol from the effect of believing one has received an active treatment. The authors used an oral placebo so that ondansetron was blinded, but the inhaled comparison could not be truly masked.
What Are the Results?
Nausea scores fell by a mean of 30 mm in the isopropyl alcohol plus ondansetron arm, 32 mm in the isopropyl alcohol plus placebo arm, and 9 mm in the saline plus ondansetron arm. The 95 percent confidence intervals for the two isopropyl alcohol arms (22 to 37 mm and 25 to 39 mm) did not overlap with the interval for the ondansetron-only arm (5 to 14 mm), indicating a clear difference. Fewer patients in the isopropyl alcohol arms needed rescue antiemetics (27.5 percent and 25.0 percent) than in the ondansetron-only arm (45.0 percent) (April et al., 2018).
The size of the difference is clinically meaningful as well as statistically significant: a reduction of more than 20 mm on a 100 mm scale is a change patients would notice. The finding that adding ondansetron to isopropyl alcohol did not improve relief at 30 minutes is also informative. It may reflect the fact that oral ondansetron takes time to be absorbed, so a 30-minute window favors a fast-acting inhaled treatment.
The findings are consistent with an earlier trial by the same research group. That double-blind trial enrolled 84 patients, 80 of whom finished, and found that ten minutes after inhalation began, the median nausea rating stood at three points in the alcohol group against six in the saline group; later use of rescue antiemetics, however, did not differ between groups (Beadle et al., 2016). The earlier trial measured relief at 10 minutes and the later one at 30, so together they suggest the effect begins quickly and is still present half an hour later. Consistency across two trials strengthens confidence that the effect is real, but both were conducted by overlapping investigators at similar military teaching hospitals, so independent replication in other emergency departments would add weight.
Will the Results Help in Caring for Patients?
The results are relevant to the composite fast-track area described in Module 1. The study population, adults with nausea not needing immediate intravenous access, closely matches the fast-track population. The intervention is inexpensive, already stocked, and simple enough to offer at triage under a nursing protocol, and the trial reported few adverse events. The main cautions are that the effect was measured over 30 minutes only, so it does not show whether relief lasts, and that the blinding concern means some of the benefit may reflect expectation. For a low-risk, low-cost intervention offered while patients wait for evaluation, that uncertainty is less concerning than it would be for a costly or risky treatment.
Conclusion
This randomized trial provides Level II evidence that inhaled isopropyl alcohol reduces nausea within 30 minutes more than oral ondansetron alone in adult emergency department patients who do not need intravenous access. Its strengths include randomization, near-complete follow-up, and a clinically meaningful effect; its weaknesses include a convenience sample, a single site, a short outcome window, and a blinding problem inherent in comparing a scented treatment with an unscented placebo. On its own the study is not enough to change practice, but it is a strong piece of the evidence that will be synthesized, with the systematic reviews found in the search, in later modules.
References
April, M. D., Oliver, J. J., Davis, W. T., Ong, D., Simon, E. M., Ng, P. C., & Hunter, C. J. (2018). Aromatherapy versus oral ondansetron for antiemetic therapy among adult emergency department patients: A randomized controlled trial. Annals of Emergency Medicine, 72(2), 184-193. https://doi.org/10.1016/j.annemergmed.2018.01.016
Beadle, K. L., Helbling, A. R., Love, S. L., April, M. D., & Hunter, C. J. (2016). Isopropyl alcohol nasal inhalation for nausea in the emergency department: A randomized controlled trial. Annals of Emergency Medicine, 68(1), 1-9. https://doi.org/10.1016/j.annemergmed.2015.09.031
Melnyk, B. M., & Fineout-Overholt, E. (2023). Evidence-based practice in nursing & healthcare: A guide to best practice (5th ed.). Wolters Kluwer.
How this N 494 Module 2 example is structured
N494 Module 2 typically asks you to select a quantitative study from your literature search and critically appraise it, identifying the study type, its level in the evidence hierarchy and its risk of bias, in an APA paper. Aspen revises courses, so check your classroom for the exact questions and length. This example continues the Module 1 PICOT, uses the three standard appraisal questions as its structure, weighs validity rather than listing design features, reports results with effect sizes and confidence intervals, and judges applicability to the student's own setting.
N494 Module 2 questions, answered
What does N494 Module 2 usually ask for?
Commonly a critical appraisal of one quantitative research study from your literature search: the study type, where it falls in the hierarchy of evidence, how reliable it is and its risk of bias, and whether the results apply to your practice. Your classroom's rubric sets the exact questions and length.
What are the three critical appraisal questions?
Are the results valid, what are the results, and will they help in caring for my patients. The sample uses them as section headings, which makes it easy for a grader to see that each has been answered.
How do I show critical thinking in an appraisal?
Explain how a specific design feature could bias the specific outcome. The sample shows that because isopropyl alcohol has a smell and saline does not, patients could guess their group, which matters for a subjective outcome like nausea. General statements such as 'the sample was small' earn less credit.
Write yours, or have the desk draft it
This paper is an original model document written by our desk, not a submitted student paper and not an official Aspen University document. Read it for the moves, then write your own to the instructions in your classroom. If you want one built to your exact prompt and rubric, the first custom sample is free and arrives in 24 to 48 hours.