Oral hygiene in the ICU: Doing away with oral chlorhexidine prophylactic rinse

De-adoption of the practice of swabbing the mouth with chlorhexidine for the prevention of ventilator-associated pneumonia (VAP) in the intensive care unit (ICU) and implementing a standard oral care bundle does not necessarily reduce mortality, infection-related ventilator-associated complications (IVACs), or procedural pain, according to the results of the CHORAL study.

But the intervention benefits oral health, said Dr Craig Dale from the University of Toronto, Canada, in a virtual presentation at this year’s Critical Care Review Meeting (eCCR21).

CHORAL was a 14-month stepped-wedge cluster randomized controlled trial conducted across six academic ICUs in Toronto, Canada. All ICU clusters commenced the study with a 2-month control period involving 0.12% chlorhexidine oral rinse, which was the pre-existing baseline practice.

The clusters sequentially crossed over to the intervention in a stepwise fashion every 2 months according to a computer-generated randomization schedule. At trial completion, all of them had fully de-adopted chlorhexidine and implemented the standardized oral care bundle comprising oral assessment, tooth brushing, moisturization, and secretion removal.

The analysis included 3,260 patients on invasive mechanical ventilation, with 1,560 in the control period and 1,700 in the intervention period (oral care bundle sans chlorhexidine). Baseline characteristics were generally similar in both study periods. However, there were marked differences in Apache II score and diagnostic categories, operative status, and the number of comorbidities, which, as Dale pointed out, is common in cluster trials.

“After adjusting for differences in baseline characteristics, we found no difference in ICU mortality between control and intervention periods (21.2 percent vs 23.5 percent; p=046). Time to IVACs did not differ (p=0.90), and procedural pain was not significantly changed (p=0.10),” Dale said. 

However, the intervention did improve oral health dysfunction scores (p=0.02) and had a good uptake, he added.

Random observation of intervention fidelity in about 340 oral care encounters demonstrated successful de-adoption of chlorhexidine in the intervention period. Dale and colleagues saw significant increases in most oral care bundle components between control and intervention periods. 

“More specifically, we noted greater than 72 percent of patients receive toothbrushing, suctioning, and oral moisturization as prescribed,” he said.

When less is more

VAP is a lung infection that occurs in patients on artificial breathing machines for more than 48 hours. Safe and effective oral care plays a critical role in the health outcomes of ICU patients on mechanical ventilation. They tend to have reduced salivary flow, contributing to abnormal oropharyngeal colonization with bacteria. [Lancet 2010;376:1339-1346; J Crit Care 2017;37:30-37; Crit Care Med 2003;31:781-786]

Aspiration of bacteria lurking in the mouth and upper respiratory tract can lead to IVACs, including VAP, and ultimately prolong time on mechanical ventilation and increase costs of treatment. It also causes xerostomia, which is associated with severe pain and discomfort. [AACN Adv Crit Care 2010;21:64-79; Intensive Care Med 2014;40:1295-1302]

To prevent VAP, evidence-based guidelines encouraged ICUs to adopt “ventilator bundles,” which incorporate the use of chlorhexidine gluconate mouth rinse. However, two updated meta-analyses suggest that the oral antiseptic may contribute to excess mortality in some patients while failing to prevent VAP. Furthermore, the attributable mortality for VAP turns out to be grossly confounded and is probably closer to just 1 percent. [J Crit Care 2008;23:126-137; JAMA Intern Med 2014;174:751-761; BMJ 2014;348:g2197; Am J Respir Crit Care Med 2011;184:1133-1139]

The evidence for a lack of benefit in VAP prevention, as well as possible harm, served as the impetus behind the CHORAL study. In light of the present data, Dale proposed that clinicians impose a moratorium on the use of chlorhexidine until further evidence supporting its efficacy and effectiveness becomes available. 

“It seems reasonable to adopt an oral care bundle into practice, since there is evidence of benefit and low risk of harm,” he said.

Considering a change in practice

Delivering an editorial on the CHORAL study, Dr Chris Nickson of the Alfred ICU in Melbourne, Australia, commended the investigators for putting the oral health of the ICU patients—which tends to be placed on the backburner—on the map.

Nickson added how it is not easy to just do away with a therapy or an intervention that the healthcare staff has gotten used to, such as components of the VAP prevention bundle.

However, the study was limited by the final patient recruitment falling short of the number anticipated in the sample size calculations, that is 4,200 patients should provide 80 percent power. There was not enough power to definitively address the issue of whether the current practice of using oral chlorhexidine should be changed, Nickson pointed out.

In response, study co-author Dr Brian Cuthberson explained that with a cluster trial, researchers are forced to look at their potential recruitment upfront, perform their power calculations, and set fixed periods for each step.

“So you’re in a situation where you’re forced to start, and you don’t really know if your numbers are going to be right until you’re so far in that you cant do very much about it,” he said. “We did end up underpowered, and that’s a disappointment.”