Issues in pulmonary nursingDuration of action of a single, early oral application of chlorhexidine on oral microbial flora in mechanically ventilated patients: a pilot study
Introduction
Pneumonia is a common complication of mechanical ventilation (ventilator-associated pneumonia [VAP]), occurring in approximately 25% of ventilated patients1, 2, 3 and is responsible for 90% of nosocomial infections in this patient population.4, 5 It is the leading cause of death from nosocomial infections6 and the second most common nosocomial infection in the United States,2 greatly adding to cost,7, 8 duration of mechanical ventilation,9, 10, 11 ICU length of stay,10, 12 hospital length of stay,13, 14 and mortality.7, 15 Data reported by the Centers for Disease Control and Prevention (CDC) through the National Nosocomial Infections Surveillance reporting system16 show that the VAP rate is the highest in trauma, burn, neurosurgical, and surgical patients.4 Patients who suffer trauma and/or undergo surgery of the head, neck, thorax, or abdomen have been shown to be at especially increased risk.4, 17, 18, 19, 20 Furthermore, endotracheal intubation of the acutely ill or injured may be performed in the field where early and repeated oropharyngeal care is not routinely done.
Colonization of the oropharynx is one of the most critical risk factors for the development of nosocomial pneumonia in intubated patients.21, 22 The vast majority of organisms that are associated with VAP have been found to colonize the oral pharynx before the VAP diagnosis.23 Dental plaque is an important site for growth of potentially pathogenic bacteria providing a nidus of infection for microorganisms that are responsible for the development of VAP.21, 24, 25, 26 In addition, the following factors increase bacterial colonization of the oropharynx in the mechanically ventilated critically ill patient after intubation. Within 48 hours of hospital admission, the composition of the oropharyngeal flora of critically ill patients undergoes a change to predominantly gram-negative organisms, constituting a more virulent flora including potential VAP pathogens.27, 28 After intubation, the endotracheal tube provides a pathway for direct entry of bacteria from the oropharynx through an open glottis to the lower respiratory tract. Therefore, reducing the number of microorganisms in the mouth reduces the pool of organisms available for translocation to and colonization of the lung. As a result, reduction of organisms in the oral cavity during the early post-intubation period with an oral care intervention is a theoretically and economically attractive method to reduce the risk of development of VAP, especially in those with the highest VAP risk, ie the trauma and surgical population.
Little is known about the effects of an early (< 24 hours) post-intubation oral care intervention in critically ill patients. Evidence-based protocols for oral care of mechanically ventilated patients after intubation are not available, and oral hygiene measures are generally directed toward patient comfort after intubation rather than microbial removal in the peri-intubation period.29 The lack of published protocols for oral care in intubated patients has been noted in the clinical nursing literature,30 and no testing of an early post-intubation oral intervention has been done. During the first 24 to 48 hours of critical illness, trauma and surgical patients are generally very unstable and nursing care is appropriately focused on achieving physiologic stability. As a result, oral care is not a high priority.31 Because oral flora change in the first 48 hours of critical illness from the usual predominance of viridans streptococci and associated colonizers to more potentially pathogenic microbes responsible for pneumonia (such as S. aureus, S. pneumoniae, A. baumanii, H. influenzae and P. aeruginosa),23, 24, 25, 26, 27 a single, early post-intubation oral intervention may reduce the growth of potential oral pathogens for 24 to 48 hours, until the patient stabilizes and routine oral care can be instituted.
Chlorhexidine gluconate (CHG) is a broad spectrum antibacterial agent that has been used extensively in healthy populations as a daily oral rinse to control plaque and to prevent and treat gingivitis.32, 33, 34, 35 In addition, 2 studies35, 36 have demonstrated reductions in respiratory tract infection rates with oral CHG use before and after elective cardiac surgery when compared with usual care. There are, however, important differences between elective surgery and the emergency surgery populations that influence oral care strategies. Elective surgery subjects are likely to have different comorbidities and better physiologic status at the time of intubation than emergently intubated patients. Respiratory tract infection rates of only 3%36 and 9%35 were noted in placebo groups of the cardiac surgery studies. In addition, both studies used chlorhexidine during several days before and after surgery. The duration of action of a single application of CHG has not been described in the critically ill population. In addition, although studies in other populations have compared CHG rinses with swab administration and found equal efficacy,37, 38 delivery of CHG by swab or spray has not been tested in the intubated, critically ill population. Before testing interventions to reduce oral microbial flora associated with VAP with a single application, the duration of action of CHG must be evaluated in this population. Therefore, the purpose of this study was (1) to describe the effect of an early post-intubation, single oral application of CHG (by spray and by swab) on oral microbial flora and (2) to describe the effect of a single oral application of CHG (by spray and by swab) on VAP.
Section snippets
Setting and sample
The study was conducted in the Emergency Department (ED), the Surgical Trauma Intensive Care Unit (STICU), and the Neuroscience Intensive Care Unit (NSICU) at Virginia Commonwealth University Medical Center. The sample of 34 subjects was drawn from all patients, 18 years of age or older, admitted to the ED, STICU, or NSICU who required endotracheal intubation and were mechanically ventilated. Patients were randomized either to one of the treatment groups (CHG by spray or swab) or to the control
Data analysis
Subjects who remained intubated for at least 12 hours were included in the data analysis for the primary aim (effect of intervention on oral microbial flora). Subjects who remained intubated for at least 48 hours were included in the data analysis for the secondary aim (effect of intervention on development of VAP), because, by definition, VAP occurs after 48 hours of intubation.
Because of the small sample size in each of the 3 groups, descriptive methods were used to document the greatest
Subjects
Thirty-four subjects were recruited (spray group 11, swab group 12, control group 11). There were equal numbers of African Americans and Caucasians; the majority were male, surgical (general, oncology, transplant, or neurosurgery) patients (Table 1). Of those enrolled in the study, oral cultures were obtained on all subjects at study admission, 31 subjects at 12 hours, 27 at 24 hours, 17 at 48 hours, and 12 at 72 hours. Twelve subjects had complete data both at admission and at 48 hours for
Discussion
Use of a single application of CHG (2 mL of 0.12%; as spray and swab) was tested in this study. Though significant differences were not found among groups, there are trends in the data that suggest that use of CHG in the early post-intubation period may mitigate or delay the development of VAP. Specifically, a decline in the level of oral bacterial growth was found only in the treatment groups. The standard self-administered CHG dose is 15 mL. Although the 2-mL dose provided sufficient coverage
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