Ventilator-associated pneumonia: update on etiology, prevention, and management

Meta-Analysis of the Efficacy and Safety of Chlorhexidine for Ventilator-Associated Pneumonia Prevention in Mechanically Ventilated Patients

Objective

To explore the efficacy and safety of chlorhexidine oral care in the prevention of ventilator-associated pneumonia (VAP) by means of meta-analysis.

Methods

Randomized controlled trials on the effect of chlorhexidine oral care on the incidence of VAP in patients on mechanical ventilation were searched in PubMed, Scopus, Cochrane Library, and Embase from May 1, 2022. Two researchers independently screened and included the study, extracted the data, and evaluated the literature quality. RevMan5.3 software was used for meta-analysis.

Results

Meta-analysis of 13 included literature studies involving 1533 patients showed that oral care with chlorhexidine solution could reduce the incidence of VAP in patients with mechanical ventilation and the difference was statistically significant (RR = 0.61, 95% CI (0.46, 0.82), P=0.04). However, the results showed that the incidence of VAP of low concentration (0.02%, 0.12%, and 0.2%) and high concentration (2%) of chlorhexidine in the intervention group was lower than that in the control group and the difference was statistically significant (RR = 0.70, 95% CI (0.51, 0.96), P=0.03; RR = 0.41, 95% CI (0.27, 0.62)). There was no significant difference in mortality between the two groups (RR = 1.01, 95% CI (0.85, 1.21), P=0.87). There was no statistical significance in days ventilated or days in ICU between the two groups (RR = -0.02, 95% CI (-0.19, 0.16), P=0.84; RR = 0.01, 95% CI (-0.11, 0.14), P=0.85).

Conclusion

Existing evidence shows that chlorhexidine used for oral care of patients with mechanical ventilation can reduce the incidence of VAP, and high concentration of chlorhexidine (2%) or low concentration of chlorhexidine (0.02%, 0.12%, 0.2%) has a significant effect on the prevention of VAP. Considering the safety of clinical application, it is recommended to use 0.02%, 0.12%, and 0.2% chlorhexidine solution for oral care.

Efficacy of antibiotic prophylaxis against ventilator-associated pneumonia

Ventilator-associated pneumonia (VAP) is one of the most important problems of intensive care units. Eighty-four neurologic patients with acute stroke (Glasgow Coma Score ≤8) were entered into a double-blind clinical trial. Patients in the intervention group received piperacillin-tazobactam 4 g/0.5 g at the time of intubation and 12 h later. The incidences of early-onset (within four days of intubation) and late-onset VAP were 9.2 and 26.9 episodes per 1000 days of mechanical ventilation in the intervention and control groups, respectively (odds ratio: 0.217; 95% confidence interval: 0.056-0.085; P = 0.028). Administration of prophylactic piperacillin-tazobactam may reduce early-onset VAP, but the benefit does not extend to late-onset VAP.

Antibiotic Utilization Patterns in Patients with Ventilator-Associated Pneumonia: A Canadian Context

This retrospective cohort study describes the patterns of antibiotic use for the treatment of ventilator-associated pneumonia (VAP) in the Calgary Zone of Alberta Health Services. Timing, appropriateness, and duration of antibiotics were evaluated in two hundred consecutive cases of VAP derived from 4 adult intensive care units (ICU). Antibiotic therapy was initiated in less than 24 hours from VAP diagnosis in 83% of cases. Although most patients (89%) received empiric therapy that demonstrated in vitro sensitivity to the identified pathogens, only 24% of cases were congruent with the 2008 Association of Medical Microbiology and Infectious Disease (AMMI) guidelines. Both ICU (p = 0.001) and hospital (p = 0.015) mortality were significantly lower and there was a trend for shorter ICU length of stay (p = 0.051) in patients who received appropriate versus inappropriate initial antibiotics. There were no outcome differences related to compliance with AMMI guidelines. This exploratory study provides insight into the use of antimicrobials for the treatment of VAP in a large Canadian health region. The discordance between the assessments of appropriateness of empiric therapy based on recovered pathogens versus AMMI guidelines is notable, emphasizing the importance of using as much as possible local microbiologic and antimicrobial resistance data.

Lack of added predictive value of portable chest radiography in diagnosing ventilator-associated pulmonary infection

INTRODUCTION

The accurate diagnosis of ventilator-associated pulmonary infection (VAPI) poses an ongoing challenge. At our institution, patients in whom VAPI is strongly suspected on the basis of the Clinical Pulmonary Infection Score (CPIS) undergo diagnostic mini-bronchoalveolar lavage (mBAL) with quantitative cultures, followed by empiric antibiotic therapy in our surgical intensive care unit (sICU). We sought to determine the role of portable chest X-radiography (pCXR) in the diagnosis of VAPI.

METHODS

We conducted a retrospective analysis of mechanically ventilated adult (>18 y of age) patients with suspected VAPI undergoing concomitant pCXR and diagnostic mBAL in a combined tertiary-care unit for trauma and surgical intensive care. Portable chest X-radiographs were evaluated in a blinded manner by surgical intensivists, critical care fellows, general surgical residents, and radiologists, and were rated as: (0) Not suspicious for pneumonia, (1) possible pneumonia, or (2) likely pneumonia. These results were compared with the microbiologic results of mBAL culture. Demographic and clinical characteristics including age, gender, white blood cell count (WBC), temperature, purulence of secretions, blood and urine culture results, and length of hospitalization were correlated with the results of mBAL.

RESULTS

Regardless of interpreter specialty or level of training, pCXR had no predictive value for VAPI. The overall sensitivity and specificity of pCXR were 77% and 74%, respectively, and its positive predictive value, negative predictive value, and receiver-operating characteristic (ROC) curve areas all had values below 50%. The inter-rater agreement (ρ) was 0.965, showing little discrepancy between raters. The degree of purulence on mBAL, concurrent blood stream infection, and increase in the number of days of hospitalization before diagnostic testing were correlated with an increased frequency of VAPI. The three CPIS criteria of febrile response, leukocytosis/leukopenia, and arterial oxygenation correlated poorly with the results of mBAL culture.

CONCLUSION

Portable chest X-radiography has no added predictive value in identifying patients who should be evaluated further for VAPI. This supports the elimination of findings on chest X-radiography as defining characteristics of VAP, which accords with the U.S. Centers for Disease Control and Prevention's recent definition of VAP as but one of a number of types of ventilator-associated pulmonary infection (VAPI).

The effect of a nurse-led multidisciplinary team on ventilator-associated pneumonia rates

Background. Ventilator-associated pneumonia (VAP) is a worrisome, yet potentially preventable threat in critically ill patients. Evidence-based clinical practices targeting the prevention of VAP have proven effective, but the most optimal methods to ensure consistent implementation and compliance remain unknown. Methods. A retrospective study of the trend in VAP rates in a community-hospital's open medical intensive care unit (MICU) after the enactment of a nurse-led VAP prevention team. The period of the study was between April 1, 2009, and September 30, 2012. The team rounded on mechanically ventilated patients every Tuesday and Thursday. They ensured adherence to the evidence-based VAP prevention. A separate and independent infection control team monitored VAP rates. Results. Across the study period, mean VAP rate was 3.20/1000 ventilator days ±5.71 SD. Throughout the study time frame, there was an average monthly reduction in VAP rate of 0.27/1000 ventilator days, P < 0.001 (CI: −0.40–−0.13). Conclusion. A nurse-led interdisciplinary team dedicated to VAP prevention rounding twice a week to ensure adherence with a VAP prevention bundle lowered VAP rates in a community-hospital open MICU. The team had interdepartmental and administrative support and addressed any deficiencies in the VAP prevention bundle components actively.

The accuracy of Gram stain of respiratory specimens in excluding Staphylococcus aureus in ventilator-associated pneumonia

OBJECTIVE

To evaluate the Gram stain of deep tracheal aspirate as a tool to direct empiric antibiotic therapy, and more specifically as a tool to exclude the need for empiric antibiotic coverage against Staphylococcus aureus in ventilator-associated pneumonia (VAP).

DESIGN

A prospective, single-center, observational, cohort study.

SETTING

All wards at a community hospital.

PATIENTS

Adult patients requiring mechanical ventilation, identified as having VAP in a 54-month prospective surveillance database.

INTERVENTIONS

Sampling of lower airway secretions by deep endotracheal aspiration was taken from each patient who developed VAP. Samples were sent immediately for Gram stain and qualitative bacterial cultures. Demographic and relevant clinical data were collected; Gram stain, culture, and antibiotic susceptibility results were documented; and outcome was followed prospectively.

MEASUREMENTS AND MAIN RESULTS

The analysis included 114 consecutive patients with 115 episodes of VAP from June 2007 to January 2012. Sensitivity of Gram stain compared with culture was 90.47% for gram-positive cocci, 69.6% for gram-negative rods, and 50% for sterile cultures. Specificity was 82.5%, 77.8%, and 79%, respectively. Negative predictive value was high for gram-positive cocci (97%) and sterile cultures (96%) but low for gram-negative rods (20%). Acinetobacter baumanii (45%) and Pseudomonas aeruginosa (38 %) were the prevailing isolates. S aureus was found in 18.3% of the patients. Most isolates were multiresistant.

CONCLUSIONS

Absence of gram-positive bacteria on Gram stain had a high negative predictive value. These data can be used to narrow the initial empiric antibiotic regimen and to avoid unnecessary exposure of patients to vancomycin and other antistaphyloccocal agents.

Eosinophil as a protective cell in S. aureus ventilator-associated pneumonia

Cell counts of leukocytes subpopulations are demonstrating to have an important value in predicting outcome in severe infections. We evaluated here the render of leukogram counts to predict outcome in patients with ventilator-associated pneumonia (VAP) caused by Staphylococcus aureus. Data from patients admitted to the ICU of Hospital Clínico Universitario de Valladolid from 2006 to 2011 with diagnosis of VAP caused by S. aureus were retrospectively collected for the study (n = 44). Leukocyte counts were collected at ICU admission and also at VAP diagnosis. Our results showed that nonsurvivors had significant lower eosinophil counts at VAP diagnosis. Multivariate Cox regression analysis performed by the Wald test for forward selection showed that eosinophil increments from ICU admission to VAP diagnosis and total eosinophil counts at VAP diagnosis were protective factors against mortality in the first 28 days following diagnosis: (HR [CI 95%], P): (0.996 [0.993–0.999], 0.010); (0.370 [0.180–0.750], 0.006). Patients with eosinophil counts <30 cells/mm³ at diagnosis died earlier. Eosinophil counts identified survivors: (AUROC [CI 95%], P): (0.701 [0.519–0.882], 0.042). Eosinophil behaves as a protective cell in patients with VAP caused by S. aureus.

Ventilator-associated complications, including infection-related complications: the way forward

Acute respiratory failure represents the most common condition requiring admission to an adult intensive care unit. Ventilator-associated pneumonia (VAP) has been used as a marker of quality for patients with respiratory failure. Hospital-based process-improvement initiatives to prevent VAP have been successfully used. The use of ventilator-associated complications (VACs) has been proposed as an objective marker to assess the quality of care for this patient population. The use of evidence-based bundles targeting the reduction of VACs, as well as the conduct of prospective studies showing that VACs are preventable complications, are reasonable first-steps in addressing this important clinical problem.

Management of critically ill patients receiving noninvasive and invasive mechanical ventilation in the emergency department

Patients requiring noninvasive and invasive ventilation frequently present to emergency departments, and may remain for prolonged periods due to constrained critical care services. Emergency clinicians often do not receive the same education on management of mechanical ventilation or have similar exposure to these patients as do their critical care colleagues. The aim of this review was to synthesize the evidence on management of patients requiring noninvasive and invasive ventilation in the emergency department including indications, clinical applications, monitoring priorities, and potential complications. Noninvasive ventilation is recommended for patients with acute exacerbation of chronic obstructive pulmonary disease or cardiogenic pulmonary edema. Less evidence supports its use in asthma and other causes of acute respiratory failure. Use of noninvasive ventilation in the prehospital setting is relatively new, and some evidence suggests benefit. Monitoring priorities for noninvasive ventilation include response to treatment, respiratory and hemodynamic stability, noninvasive ventilation tolerance, detection of noninvasive ventilation failure, and identification of air leaks around the interface. Application of injurious ventilation increases patient morbidity and mortality. Lung-protective ventilation with low tidal volumes based on determination of predicted body weight and control of plateau pressure has been shown to reduce mortality in patients with acute respiratory distress syndrome, and some evidence exists to suggest this strategy should be used in patients without lung injury. Monitoring of the invasively ventilated patient should focus on assessing response to mechanical ventilation and other interventions, and avoiding complications, such as ventilator-associated pneumonia. Several key aspects of management of noninvasive and invasively ventilated patients are discussed, with a particular emphasis on initiation and ongoing monitoring priorities focused on maintaining patient safety and improving patient outcomes.

Recent advances in chronic thromboembolic pulmonary hypertension

Surgical excellence in pulmonary thromboendarterectomy (PTE) for chronic thromboembolic pulmonary hypertension (CTEPH) has begun to spread around the world. The perioperative mortality for this procedure is typically under 10%. The maximal benefit from PTE is derived in those patients who have a high proximal clot burden that is surgically accessible, as outlined by the Jamieson classification. Residual pulmonary hypertension after successful PTE is common and increasingly is managed with maintenance oral pulmonary vasodilator therapy such as endothelin antagonists, phosphodiesterase inhibitors, and/or prostaglandins. The role of pulmonary vasodilator therapy in CTEPH before PTE is limited and should not delay definitive surgical therapy. Although plain deep hypothermic circulatory arrest (DHCA) is the classic technique for CTEPH, alternatives such as DHCA with antegrade cerebral perfusion are feasible as well. Prolonged mechanical ventilation after PTE remains common in part because of reperfusion pulmonary edema. Careful perioperative management can reduce the incidence of this syndrome. Because ventilator-associated pneumonia is also a common complication after PTE, it represents a major opportunity for outcome improvement, particularly because there are multiple modalities for its prevention and prompt diagnosis.