Our text defines a hypothesis as “a claim about a population parameter (population proportion or population mean) or some other characteristic of a population” (Bennett et. al., 2018). According to Bennett et. al. (2018) a hypothesis test refers to a standard method of testing whether a claim can be supported by available evidence. In order to perform a hypothesis test, you must have a null hypothesiswhich is the beginning assumption that claims a specific value for the population parameter being tested and takes the form of equality, and you must also have an alternative hypothesiswhich is a claim that the population parameter being tested is opposite of or differsfrom the null hypothesis value (Bennett et. al., 2018).
As a critical care nurse, I see many patients daily that are on ventilators for airway management and support. “Ventilator-associated pneumonia (VAP) is one of the most commonly encountered hospital-acquired infections in intensive care units and is associated with significant morbidity and high costs of care” (Keyt et. al., 2014). A study that could be done at our facility, or any critical care facility for that matter, could be a hypothetical study of preventative measures for development VAP. For example, our facility could claim providing oral care every 4 hours with chlorhexidine gluconate results in the reduction of VAP development by 20% or more. This would be our null hypothesis. As for the alternative hypothesis, it would state that providing oral care with chlorhexidine gluconate every 4 hours reduces VAP development by less than 20%. In our lesson we learned that the outcome of a hypothesis test neither proves or disproves the claim; it only provides us with the evidence to support or refute the claim.
In 2012, members of the Department of Periodontology conducted a study to evaluate the effectiveness of oral decontamination on VAP prevention. Their study found that out of 61 ventilator dependent ICU patients, 34 developed VAP (55.7%) within 6.8 d. The rate of VAP development was significantly higher in the control group (in which they used saline mouth swabs) than in the chlorhexidine group (68.8% vs. 41.4%, respectively; p = 0.03) with an odds ratio of 3.12 (95% confidence interval = 1.09-8.91). The findings of this study suggest “oral care with chlorhexidine swabbing reduces the risk of VAP development in mechanically ventilated patients, strongly supports its use in ICUs and indeed the importance of adequate oral hygiene in preventing medical complications” (Ozcaka et. al., 2012).
If our facility were to conduct a similar study and the outcomes were such as these, we would not rejectthe null hypothesis because the group’s VAP rates who received oral care with chlorhexidine were decreased by 27.4% when compared to the group that received oral care with saline swabs. This means that the evidence obtained by the study is sufficient in supporting our claim that providing oral care with chlorhexidine gluconate every 4 hours reduces VAP rates by 20% or more.
Many times, we have nurses that think oral care is a waste of time or should be done but isn’t really all that important. If we could put the data for their particular facility in front of them to prove that sometimes it is oral care that makes the difference for patient’s not acquiring VAP, I believe that could change their perspective and encourage compliance with providing the patients with oral care every 4 hours and even as needed between those 4 hours.
Bennett, J., Briggs, W. L., Triola, M.F. (2018). Statistical Reasoning for Everyday Life 5th Edition.Pearson.
Keyt, H., Faverio, P., & Restrepo, M. I. (2014). Prevention of ventilator-associated pneumonia in the intensive care unit: a review of the clinically relevant recent advancements. The Indian journal of medical research, 139(6), 814-21. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4164993/#ref45 (Links to an external site.)
Özçaka Ö, B. O. (2012, October). Chlorhexidine decreases the risk of ventilator-associated pneumonia in intensive care unit patients: a randomized clinical trial.Retrieved from PubMed.gov: https://www.ncbi.nlm.nih.gov/pubmed/22376026 (Links to an external site.)