New issues and controversies in the prevention of ventilator-associated pneumonia

Prevention of ventilator-associated pneumonia through aspiration of subglottic secretions: a systematic review and meta-analysis

Ventilator-associated pneumonia (VAP) is a subset of hospital-acquired pneumonias and is a serious, sometimes fatal, complication in patients who need mechanical ventilation. In addition, pay-for-performance initiative has placed increased emphasis on preventing nosocomial infections including VAP. Facilities may not be reimbursed for costs associated with prevalence infections. This article presents a review and meta-analysis of the prevention of VAP through the aspiration of subglottic secretion.

A clinical assessment of the Mucus Shaver: a device to keep the endotracheal tube free from secretions

OBJECTIVE

: We evaluated a new device designed to clean the endotracheal tube in mechanically ventilated patients, the Mucus Shaver.

DESIGN

: Prospective, randomized trial.

SETTING

: University hospital intensive care unit.

PATIENTS

: We enrolled 24 patients expected to remain ventilated for >72 hrs.

INTERVENTIONS

: The Mucus Shaver is a concentric inflatable catheter for the removal of mucus and secretions from the interior surface of the endotracheal tube. The Mucus Shaver is advanced to the distal endotracheal tube tip, inflated, and subsequently withdrawn over a period of 3-5 secs. Patients were prospectively randomized within 2 hrs of intubation to receive standard endotracheal tube suctioning treatment or standard suctioning plus Mucus Shaver use until extubation.

MEASUREMENTS AND MAIN RESULTS

: During the study period, demographic data, recent medical history, adverse events, and staff evaluation of the Mucus Shaver were recorded. At extubation, each endotracheal tube was removed, cultured, and analyzed by scanning electron microscopy. Twelve patients were assigned to the study group and 12 were assigned to the control group. No adverse events related to the use of the Mucus Shaver were observed. At extubation, only one endotracheal tube from the Mucus Shaver group was colonized, whereas in the control group ten endotracheal tubes were colonized (8% vs. 83%; p < .001). Scanning electron microscopy showed little secretions on the endotracheal tubes from the study group, whereas thick bacterial deposits were present on all the endotracheal tubes from the control group (p < .001 by Fisher exact test, using a maximum biofilm thickness of 30 μm as cut-off). The nursing staff was satisfied by the overall safety, feasibility, and efficacy of the Mucus Shaver.

CONCLUSIONS

: The Mucus Shaver is a safe, feasible, and efficient device for endotracheal tube cleaning in the clinical setting. The Mucus Shaver is helpful in preventing endotracheal tube colonization by potentially harmful microorganisms.

Early ICU energy deficit is a risk factor for Staphylococcus aureus ventilator-associated pneumonia

BACKGROUND

Caloric insufficiency during the first week of ICU stay has been associated with increased infection rates. The connection between specific pathogens and host nutritional status in the ICU is not well known. This study was undertaken to determine the impact of patients' early in-ICU energy balance on the pathogens responsible for ventilator-associated pneumonia (VAP).

METHODS

In this prospective, observational, cohort study conducted in a teaching hospital ICU, energy balance (energy delivered - calculated resting energy expenditure) was compared according to the microbiologic results of the fiber-optic BAL cultures of 76 consecutive patients receiving acute prolonged (≥ 96 h) mechanical ventilation who developed VAP during their ICU stay.

RESULTS

Among the 76 BAL cultures, 22 contained significant Staphylococcus aureus concentrations. The cumulated energy deficit of patients with S aureus VAP was greater than those with VAP caused by other pathogens (-10,275 ± 4,211 kcal vs -7,376 ± 4,013 kcal from ICU admission to day of BAL, P < .01). ICU admission, nutritional status, and conditions potentially limiting feeding did not differ significantly between the two groups. Patients with S aureus VAP had lower prescribed and delivered energy, causing higher energy deficits. Multivariate analysis identified energy deficit as being independently associated with S aureus VAP. More-severe energy deficit and higher rate of S aureus-positive BAL cultures (P = .01 comparing quartiles) were observed.

CONCLUSIONS

Early ICU energy deficit is an independent determinant for acquiring S aureus VAP in patients on acute prolonged mechanical ventilation.

Impact of the ventilator bundle on ventilator-associated pneumonia in intensive care unit

OBJECTIVE

The ventilator bundle is being promoted to prevent adverse events in ventilated patients including ventilator-associated pneumonia (VAP). We aimed to: (i) examine adoption of the ventilator bundle elements; (ii) determine effectiveness of individual elements and setting characteristics in reducing VAP; (iii) determine effectiveness of two infection-specific elements on reducing VAP; and, (iv) assess crossover effects of complying with VAP elements on central line-associated bloodstream infections.

DESIGN

Cross-sectional survey.

SETTING

Four hundred and fifteen ICUs from 250 US hospitals.

PARTICIPANTS

Managers/directors of infection prevention and control departments.

INTERVENTIONS

Adoption and compliance with ventilator bundle elements.

MAIN OUTCOME MEASURES

VAP rates.

RESULTS

The mean VAP rate was 2.7/1000 ventilator days. Two-thirds (n = 284) reported presence of the full ventilator bundle policy. However, only 66% (n = 188/284) monitored implementation; of those, 39% (n = 73/188) reported high compliance. Only when an intensive care unit (ICU) had a policy, monitored compliance and achieved high compliance were VAP rates lower. Compliance with individual elements or just one of two infection-related element had no impact on VAP (β = -0.79, P= 0.15). There was an association between complying with two infection elements and lower rates (β = -1.81, P< 0.01). There were no crossover effects. Presence of a full-time hospital epidemiologist (HE) was significantly associated with lower VAP rates (β = -3.62, P< 0.01).

CONCLUSIONS

The ventilator bundle was frequently present but not well implemented. Individual elements did not appear effective; strict compliance with infection elements was needed. Efforts to prevent VAP may be successful in settings of high levels of compliance with all infection-specific elements and in settings with full-time HEs.

Prevention of ventilator-associated pneumonia with oral antiseptics: a systematic review and meta-analysis

BACKGROUND

We did a systematic review and random effects meta-analysis of randomised trials to assess the effect of oral care with chlorhexidine or povidone-iodine on the prevalence of ventilator-associated pneumonia versus oral care without these antiseptics in adults.

METHODS

Studies were identified through PubMed, CINAHL, Web of Science, CENTRAL, and complementary manual searches. Eligible studies were randomised trials of mechanically ventilated adult patients receiving oral care with chlorhexidine or povidone-iodine. Relative risks (RR) and 95% CIs were calculated with the Mantel-Haenszel model and heterogeneity was assessed with the I(2) test.

FINDINGS

14 studies were included (2481 patients), 12 investigating the effect of chlorhexidine (2341 patients) and two of povidone-iodine (140 patients). Overall, antiseptic use resulted in a significant risk reduction of ventilator-associated pneumonia (RR 0.67; 95% CI 0.50-0.88; p=0.004). Chlorhexidine application was shown to be effective (RR 0.72; 95% CI 0.55-0.94; p=0.02), whereas the effect resulting from povidone-iodine remains unclear (RR 0.39; 95% CI 0.11-1.36; p=0.14). Heterogeneity was moderate (I(2)=29%; p=0.16) for the trials using chlorhexidine and high (I(2)=67%; p=0.08) for those assessing povidone-iodine use. Favourable effects were more pronounced in subgroup analyses for 2% chlorhexidine (RR 0.53, 95% CI 0.31-0.91), and in cardiosurgical studies (RR 0.41, 95% CI 0.17-0.98).

INTERPRETATION

This analysis showed a beneficial effect of oral antiseptic use in prevention of ventilator-associated pneumonia. Clinicians should take these findings into account when providing oral care to intubated patients.

FUNDING

None.

What is new in the prevention of ventilator-associated pneumonia?

PURPOSE OF REVIEW

Ventilator-associated pneumonia (VAP) remains a frequent and severe complication in endotracheally intubated patients. Strict adherence to preventive measures reduces the risk of VAP. The objective of this paper is to review what has come forward in recent years in the nonpharmacological prevention of VAP.

RECENT FINDINGS

It seems advantageous to implement care bundles rather than single prevention measures. A solid basis of knowledge seems necessary to facilitate implementation and maintain a high adherence level. Continuous educational efforts have a beneficial effect on attitude toward VAP. Intermittent subglottic secretions drainage, continuous lateral rotation therapy, and polyurethane cuffed endotracheal tubes decrease the risk of pneumonia. In an in-vitro setting, an endotracheal tube with a taper-shaped cuff appears to better prevent fluid leakage compared to cylindrical polyurethane or polyvinylchloride cuffed tubes. Cuff pressure control by means of an automatic device and multimodality chest physiotherapy need further investigation, as do some aspects of oral hygiene.

SUMMARY

New devices and strategies have been developed to prevent VAP. Some of these are promising but need further study. In addition, more attention is being given to factors that might facilitate the implementation process and the challenge of achieving high adherence rates.

Prevention of VAP: is zero rate possible?

Infection prevention measures, specifically targeting ventilator-associated pneumonia (VAP), have been purposed as quality-of-care indicators for patients in intensive care units. The authors discuss some of the recent evidence of the prevention of nosocomial infections, with a particular emphasis on VAP. Moreover, there are several pitfalls in considering VAP rates as a safety indicator. Because of these limitations, the authors recommend the use of specific process measures, designed to reduce VAP, as the basis for interinstitutional benchmarking.

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.

Differences in biofilm formation and antimicrobial resistance of Pseudomonas aeruginosa isolated from airways of mechanically ventilated patients and cystic fibrosis patients

Pseudomonas aeruginosa biofilms exhibit increased antimicrobial resistance compared with planktonic isolates and are implicated in the pathogenesis of both acute and chronic lung infections. Whilst antibiotic choices for both infections are based on planktonic antibiotic susceptibility results, differences in biofilm-forming ability between the two diseases have not previously been explored. The aim of this study was to compare differences in biofilm formation and antibiotic resistance of P. aeruginosa isolated from intubated patients and from patients with chronic pulmonary disease associated with cystic fibrosis (CF). The temporal evolution of antibiotic resistance in clonal P. aeruginosa strains isolated from CF patients during periods of chronic infection and acute pulmonary exacerbation was also evaluated. Biofilm formation and biofilm antibiotic susceptibilities were determined using a modified microtitre plate assay and were compared with antibiotic susceptibility results obtained using traditional planktonic culture. Clonality was confirmed using random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) analysis. Pseudomonas aeruginosa isolates collected from intubated patients produced substantially more biofilms compared with CF isolates. There was considerable heterogeneity in biofilm-forming ability amongst the CF isolates and this was unrelated to pulmonary status. Biofilm antibiotic resistance developed rapidly amongst clonal CF isolates over time, whilst traditional antibiotic resistance determined using planktonic cultures remained stable. There was a significant positive correlation between imipenem/cilastatin and ceftazidime resistance and biofilm-forming ability. The variability in biofilm-forming ability in P. aeruginosa and the rapid evolution of biofilm resistance may require consideration when choosing antibiotic therapy for newly intubated patients and CF patients.