DIAGNOSIS AND DIFFERENTIAL DIAGNOSIS OF VENTILATOR-ASSOCIATED PNEUMONIA

The utility of endotracheal aspirate bacteriology in identifying mechanically ventilated patients at risk for ventilator associated pneumonia: a single-center prospective observational study

Background

Ventilator-associated pneumonia (VAP) is a well-known, life-threatening disease that persists despite preventative measures and approved antibiotic therapies. This prospective observational study investigated bacterial airway colonization, and whether its detection and quantification in the endotracheal aspirate (ETA) is useful for identifying mechanically ventilated ICU patients who are at risk of developing VAP.

Methods

240 patients admitted to 3 ICUs at the Lahey Hospital and Medical Center (Burlington, MA) between June 2014 and June 2015 and mechanically ventilated for > 2 days were included. ETA samples and clinical data were collected. Airway colonization was assessed, and subsequently categorized into “heavy” and “light” by semi-quantitative microbiological analysis of ETAs. VAP was diagnosed retrospectively by the study sponsor according to a pre-specified pneumonia definition.

Results

Pathogenic bacteria were isolated from ETAs of 125 patients. The most common species isolated was S. aureus (56.8%), followed by K. pneumoniae, P. aeruginosa, and E. coli (35.2% combined). VAP was diagnosed in 85 patients, 44 (51.7%) with no bacterial pathogen, 18 associated with S. aureus and 18 Gram-negative-only cases, and 5 associated with other Gram-positive or mixed species. A higher proportion of patients who were heavily colonized with S. aureus developed VAP (32.4%) associated with S. aureus compared to those lightly colonized (17.6%). The same tendency was seen for patients heavily and lightly colonized with Gram-negative pathogens (30.0 and 0.0%, respectively). Detection of S. aureus in the ETA preceded S. aureus VAP by approximately 4 days, while Gram-negative organisms were first detected 2.5 days prior to Gram-negative VAP. VAP was associated with significantly longer duration of mechanical ventilation and hospitalization regardless of microbiologic cause when compared to patients who did not develop VAP.

Conclusions

The overall VAP rate was 35%. Heavy tracheal colonization supported identification of patients at higher risk of developing a corresponding S. aureus or Gram-negative VAP. Detection of bacterial ETA-positivity tended to precede VAP.

Electronic supplementary material

The online version of this article (10.1186/s12879-019-4367-7) contains supplementary material, which is available to authorized users.

Effectiveness of heat and moisture exchangers in preventing ventilator-associated pneumonia in critically ill patients: a meta-analysis

BACKGROUND

Patients may acquire ventilator-associated pneumonia (VAP) by aspirating the condensate that originates in the ventilator circuit upon use of a conventional humidifier. The bacteria that colonize the patients themselves can proliferate in the condensate and then return to the airways and lungs when the patient aspirates this contaminated material. Therefore, the use of HME might contribute to preventing pneumonia and lowering the VAP incidence. The aim of this study was to evaluate how the use of HME impacts the probability of VAP occurrence in critically ill patients.

METHODS

On the basis of the acronym "PICO" (Patient, Intervention, Comparison, Outcome), the question that guided this review was "Do critically ill patients under invasive mechanical ventilation present lower VAP incidence when they use HME as compared with HH?". Two of the authors of this review searched the databases PUBMED/Medline, The Cochrane Library, and Latin-American and Caribbean Literature in Health Sciences, LILACS independently; they used the following keywords: "heat and moisture exchanger", AND "heated humidifier", AND "ventilator-associated pneumonia prevention". This review included papers in the English language published from January 1990 to December 2012.

RESULTS

This review included ten studies. Comparison between the use of HME and HH did not reveal any differences in terms of VAP occurrence (OR = 0.998; 95% CI: 0.778-1.281). Together, the ten studies corresponded to a total sample of 1077 and 953 patients in the HME and HH groups, respectively; heterogeneity among the investigations was low (I(2) < 50%). Information about the outcome mortality was available in only eight of the ten studies. The use of HME and HH did not afford different results in terms of mortality (OR = 1.09; 95% CI: 0.864-1.376). The total sample size was 884 and 762 patients, respectively. Heterogeneity among the studies was low (I(2) = 0.0%).

CONCLUSION

Current meta-analysis was not sufficient to definitely exclude an associate between heat and moisture exchangers and VAP. Despite the methodological limitations found in selected clinical trials, the current meta-analysis suggests that HME does not decrease VAP incidence or mortality in critically ill patients.

Alternative diagnosis in the putative ventilator-associated pneumonia patient not meeting lavage-based diagnostic criteria

BACKGROUND

The clinical picture of ventilator-associated pneumonia (VAP) can be mimicked by other infectious and non-infectious diseases. The aim of this study was to determine the alternative diagnoses and to develop a diagnostic flow chart for patients suspected of having VAP not meeting the diagnostic broncho-alveolar lavage (BAL) criteria.

METHODS

Adult intensive care patients with a clinical suspicion of VAP and negative BAL results were included. The clinical suspicion of VAP was based on the combination of clinical, radiological, and microbiological criteria. BAL was considered positive if cell differentiation revealed ≥ 2% cells with intracellular organisms and/or quantitative culture results of ≥ 10(4) cfu/ml. The most likely alternative diagnosis of fever and pulmonary densities was retrospectively determined by two authors independently.

RESULTS

In all, 110 of 207 patients with suspected VAP did not meet the diagnostic BAL criteria and required further diagnostic evaluation. In 67 patients an alternative diagnosis for fever could be found. In 51 patients an alternative diagnosis of both fever and pulmonary densities could be established. In almost 40% of patients no alternative diagnosis could be provided. Non-bacterial pneumonia was diagnosed in 10 patients with Herpes simplex virus 1 (HSV-1) as the most common pathogen. In eight patients non-infectious pneumonitis was diagnosed.

CONCLUSION

Due to the wide range of alternative diagnoses and applied tests the diagnostic work-up proved to be necessarily individualized and guided by repeated clinical assessment. The most frequently found alternative diagnoses were viral pneumonia and non-infectious pneumonitis.

Hospital-acquired pneumonia in patients undergoing coronary artery bypass graft; comparison of the center for disease control clinical criteria with physicians' judgment

BACKGROUND

Following coronary artery bypass graft (CABG), patients are at high risk (3.2%-8.3%) for developing hospital-acquired pneumonia (HAP) with mortality rate of 24% to 50%. Some of routine features in patients undergoing CABG are similar to clinical criteria of Center of Disease Control (CDC) for diagnosis of pneumonia. This may lead to over-diagnosis of pneumonia in these patients.

OBJECTIVES

This study aimed to assess the frequency of CDC criteria for diagnosis of pneumonia in patients undergoing CABG.

PATIENTS AND METHODS

This study was performed on CABG candidates admitted to post cardiac surgery Intensive Care Unit (ICU) in a six-month period. Patient's records, Chest-X-Ray, and Laboratory tests were assessed for PNU1-CDC criteria for HAP diagnosis. At the same time, a physician who was unaware of the study protocol assessed the clinical diagnosis. Then the results were compared with CDC criteria-based diagnosis.

RESULTS

Of total 300 patients, 9 (3%) met CDC criteria for diagnosis of pneumonia while none of the cases were diagnosed as HAP according to the physicians' clinical diagnosis. All nine patients were discharged with proper general condition and no need of antibiotic therapy. This study showed that loss of consciousness, tachypnea, dyspnea, PaO2 < 60 mm Hg, PaO2/FiO2 < 240, and local infiltration in 24 hours of operation were misleading features of CDC criteria, which were not considered in physicians' clinical judgment to establish the diagnosis.

CONCLUSIONS

Our findings suggest that in Post-CABG patients, physicians could judge the occurrence of HAP more accurately in comparison to making the diagnosis based on CDC criteria alone. Expert physician may intentionally do not take some of these criteria into account according the patients' course of disease. Therefore, it is suggested that the value of these criteria in special group of patients like those undergoing CABG should be re-evaluated.

[Impact of early elective tracheotomy in critically ill patients]

INTRODUCTION

Tracheotomy is one of the most frequent surgical procedures performed in critically ill patients hospitalized at intensive care units. The ideal timing for a tracheotomy is still controversial, despite decades of experience.

OBJECTIVE

To determine the impact of performing early tracheotomies in critically ill patients on duration of mechanical ventilation, intensive care unit stay, overall hospital stay, morbidity, and mortality.

METHODS

Retrospective and observational study of cases subjected to elective tracheotomy at one of the intensive care units of this hospital during five consecutive years. The patients were stratified into two groups: early tracheotomy group (tracheotomy performed from day one up to and including day seven of mechanical ventilation) and late tracheotomy group (tracheotomy performed after day seven). The outcomes of the groups were compared.

RESULTS

In the early tracheotomy group, there was a statistically significant reduction in duration of mechanical ventilation (6 days vs. 19 days; p<0.001), duration of intensive care unit stay (10 days vs. 28 days; p=0.001), and incidence of ventilator-associated pneumonia (1 case vs. 44 cases; p=0.001).

CONCLUSION

Early tracheotomy has a significant positive impact on critically ill patients hospitalized at this intensive care unit. These results support the tendency to balance the risk-benefit analysis in favor of early tracheotomy.

Improving Antibiotic De-Escalation in Suspected Ventilator-Associated Pneumonia: An Observational Study With a Pharmacist-Driven Intervention

BACKGROUND

Recommendations for treatment of ventilator-associated pneumonia (VAP) emphasize early empiric broad-spectrum antibiotics. However, appropriate antibiotic de-escalation is also critical for optimal patient care.

MATERIALS AND METHODS

We examined how often intensivists in our institution appropriately de-escalated antibiotics in cases of suspected VAP, and whether decision support by intensive care unit pharmacists could improve rates of antibiotic targeting and early antibiotic discontinuation in low-risk patients.

MAIN RESULTS

A total of 92 (observation phase = 50; intervention phase = 42) patients with suspected VAP were identified. During the observation phase, 39 cases yielded positive sputum cultures, but in only 23 (59%) were antibiotics targeted to culture results. This rate improved during the intervention phase when 29 (91%) of 32 cases with positive cultures were targeted (P value .003). There were 48 cases in which the risk of pneumonia was considered low. Of the 26 low-risk cases in the observation phase, 5 (19%) had antibiotics discontinued early versus 5 (23%) of the 22 cases in the intervention phase.

CONCLUSIONS

Decision support by clinical pharmacists significantly improved rates of appropriate antibiotic targeting in cases of culture-positive suspected VAP but did not have a significant effect on early antibiotic discontinuation in patients at low risk of true pneumonia.

Common complications in the critically ill patient

Critically ill patients in intensive care units are subject to many complications associated with therapy. Many of these complications are health care-associated infections and are related to indwelling devices, including ventilator-associated pneumonia, central line-associated bloodstream infection, catheter-associated urinary tract infection; surgical site infection, venous thromboembolism, deep venous thrombosis, and pulmonary embolus are other common complications. All efforts should be undertaken to prevent these complications in surgical critical care, and national efforts are under way for each of these complications. In this article, epidemiology, risk factors, diagnosis, treatment, and prevention of these complications in critically ill patients are discussed.

Bilateral versus unilateral bronchoalveolar lavage for the diagnosis of ventilator-associated pneumonia

BACKGROUND

Ventilator-associated pneumonia (VAP) complicates the clinical course of critically injured intubated patients. Bronchoscopic bronchoalveolar lavage (BAL) represents an invasive and accurate means of VAP diagnosis. Unilateral and blinded techniques offer less invasive alternatives to bronchoscopic BAL. This study evaluated clinical criteria as well as unilateral directed versus bilateral BAL for VAP diagnosis.

METHODS

A retrospective chart review of 113 consecutive intubated trauma patients with clinically suspected VAP undergoing unilateral versus bilateral BAL was performed with comparison of positive culture results (>10(4) colony-forming units [CFU]/mL). Culture results were compared with chest radiograph (CXR) infiltrates and white blood cell (WBC) count elevation.

RESULTS

Bilateral BAL was more likely to be positive than unilateral BAL (50.4% vs. 25.5%). In 37.1% of bilateral BALs, there was discordance between the sides of positivity or the bacteria isolated. A CXR infiltrate and WBC count elevation did not predict positive BAL.

CONCLUSIONS

Clinical indicators of VAP are inaccurate, and bilateral bronchoscopic BAL is more likely than unilateral BAL to provide a positive sample in intubated trauma patients. Techniques that do not sample both lungs reliably should be avoided for diagnosis in this patient population.

Effect of heat and moisture exchangers on the prevention of ventilator-associated pneumonia in critically ill patients

Ventilator-associated pneumonia (VAP) remains one of the major causes of infection in the intensive care unit (ICU) and is associated with the length of hospital stay, duration of mechanical ventilation, and use of broad-spectrum antibiotics. We compared the frequency of VAP 10 months prior to (pre-intervention group) and 13 months after (post-intervention group) initiation of the use of a heat and moisture exchanger (HME) filter. This is a study with prospective before-and-after design performed in the ICU in a tertiary university hospital. Three hundred and fourteen patients were admitted to the ICU under mechanical ventilation, 168 of whom were included in group HH (heated humidifier) and 146 in group HME. The frequency of VAP per 1000 ventilator-days was similar for both the HH and HME groups (18.7 vs 17.4, respectively; P = 0.97). Duration of mechanical ventilation (11 vs 12 days, respectively; P = 0.48) and length of ICU stay (11 vs 12 days, respectively; P = 0.39) did not differ between the HH and HME groups. The chance of developing VAP was higher in patients with a longer ICU stay and longer duration of mechanical ventilation. This finding was similar when adjusted for the use of HME. The use of HME in intensive care did not reduce the incidence of VAP, the duration of mechanical ventilation, or the length of stay in the ICU in the study population.

Postoperative pulmonary complications: pneumonia and acute respiratory failure

Postoperative pulmonary complications (atelectasis, pneumonia, pulmonary edema, acute respiratory failure) are common, particularly after abdominal and thoracic surgery, pneumonia and atelectasis being the most common. Postoperative pneumonia is associated with increased morbidity, length of hospital stay, and costs. Few institutions have pneumonia prevention programs for surgical patients, and these should be strongly considered. Acute respiratory failure is a life-threatening pulmonary complication that requires institution of mechanical ventilation and admission to the intensive care unit, and is associated with increased risk for ventilator-associated pneumonia. This article discusses epidemiology, risk factors, diagnosis, treatment, and prevention of these pulmonary complications in surgical patients.

Significant Reduction of Ventilator-Associated Pneumonia Rates Associated With the Introduction of a Prevention Protocol and Maintained for 10 Years

Objective: To determine if the institution of a ventilator-associated pneumonia (VAP) prevention protocol was associated with VAP decrease in mechanically ventilated patients at a long-term acute care (LTAC) hospital over time. Introduction: VAP is the most common serious nosocomial infectious disease in mechanically ventilated patients. It has a high mortality and morbidity and significantly increases the cost of care. Design: A prospective preintervention and postintervention observational study comparing the number of episodes of VAP per 1000 patient ventilator-days in the 16 months preceding and 120 months (10 years) after the introduction of a VAP prevention protocol. Setting: A 73-bed, university-affiliated LTAC hospital. Methods: The implementation of a VAP prevention protocol included the following: (1) head of bed raised at 30°; (2) twice-weekly whole-body chlorhexidine-based bath with mupirocin 2% ointment applied to nares; (3) adequate hand washing; (4) adequate nutrition; (5) early tracheotomy by Day 7 if patients had endotracheal tubes; (6) monitor staff compliance; (7) infection control–run campaign involving posters, handouts, small group education events, positive reinforcement of good infection control practices, and focus on hand washing and universal precautions. Results: The initial VAP rate of 6.1 fell to 1.98/1000 ventilator-days within 5 months ( P < .001), and this was maintained. Relative risk was 0.32 ( P = .001) (68% relative risk reduction). Conclusion: The institution of a VAP prevention protocol showed a significant reduction in VAP episodes after the first 5 months of implementation. This rate was sustained for 10 years.

Early tracheotomy in elderly patients results in less ventilator-associated pneumonia

OBJECTIVES

To determine if the timing of tracheotomy in elderly patients results in less ventilator associated-pneumonia, mortality, and morbidity.

STUDY DESIGN

Historical cohort study.

SUBJECTS AND METHODS

This study included 158 ICU patients aged >65 who underwent tracheotomy from March 2003 to June 2007. Patient demographics, outcomes, and ventilation data were collected and analyzed.

RESULTS

The early tracheotomy group (continuous intubation time <7 days) included 43 patients, and 115 patients were included in the late group. There were no statistically significant differences in the demographics of the two groups. A statistically significant difference in the rate of ventilator-associated pneumonia was noted in the early versus late tracheotomy group (-0.29% VAP, 95% CI: -0.46, -0.12). There were more intubations per patient noted in the early tracheotomy group versus the late tracheotomy group (0.70 intubations, 95% CI: 0.41, 0.99). The early tracheotomy group has a lower total ICU admission time (-9.5 days, 95% CI: -21.81, -2.25) and total hospital admission time (-10 days, 95% CI: -33.69, -2.249). There was no difference in mortality, although there was a trend of lower mortality in the early tracheotomy group (-11.3% mortality, 95% CI: -0.27, -0.05).

CONCLUSION

Early tracheotomy in elderly patients is associated with less ventilator-associated pneumonia, more frequent intubations, less total admission time, and a trend toward lower mortality.

Optimal management therapy for Pseudomonas aeruginosa ventilator-associated pneumonia: An observational, multicenter study comparing monotherapy with combination antibiotic therapy*

OBJECTIVE

To evaluate whether one antibiotic achieves equal outcomes compared with combination antibiotic therapy in patients with Pseudomonas aeruginosa ventilator-associated pneumonia.

DESIGN

A retrospective, multicenter, observational, cohort study.

SETTING

Five intensive care units in Spanish university hospitals.

PATIENTS

Adult patients identified to have monomicrobial episodes of ventilator-associated pneumonia with significant quantitative respiratory cultures for P. aeruginosa.

INTERVENTIONS

None.

MEASUREMENT AND MAIN RESULTS

A total of 183 episodes of monomicrobial P. aeruginosa ventilator-associated pneumonia were analyzed. Monotherapy alone was used empirically in 67 episodes, being significantly associated with inappropriate therapy (56.7% vs. 90.5%, p < .001). Hospital mortality was significantly higher in the 40 patients with inappropriate therapy compared with those at least on antibiotic with activity in vitro (72.5% vs. 23.1%, p < .05). Excess mortality associated with monotherapy was estimated to be 13.6% (95% confidence interval -2.6 to 29.9). The use of monotherapy or combination therapy in the definitive regimen did not influence mortality, length of stay, development of resistance to the definitive treatment, or appearance of recurrences. Inappropriate empirical therapy was associated with increased mortality (adjusted hazard ratio 1.85; 95% confidence interval 1.07-3.10; p = .02) in a Cox proportional hazard regression analysis, after adjustment for disease severity, but not effective monotherapy (adjusted hazard ratio 0.90; 95% confidence interval 0.50-1.63; p = .73) compared with effective combination therapy (adjusted hazard ratio 1). The other two variables also independently associated with mortality were age (adjusted hazard ratio 1.02; 95% confidence interval 1.01-1.04; p = .005) and chronic cardiac insufficiency (adjusted hazard ratio 1.90; 95% confidence interval 1.04-3.47; p = .035).

CONCLUSIONS

Initial use of combination therapy significantly reduces the likelihood of inappropriate therapy, which is associated with higher risk of death. However, administration of only one effective antimicrobial or combination therapy provides similar outcomes, suggesting that switching to monotherapy once the susceptibility is documented is feasible and safe.

Ventilator-associated pneumonia: diagnosis, treatment, and prevention

While critically ill patients experience a life-threatening illness, they commonly contract ventilator-associated pneumonia. This nosocomial infection increases morbidity and likely mortality as well as the cost of health care. This article reviews the literature with regard to diagnosis, treatment, and prevention. It provides conclusions that can be implemented in practice as well as an algorithm for the bedside clinician and also focuses on the controversies with regard to diagnostic tools and approaches, treatment plans, and prevention strategies.

Effect of critical illness polyneuropathy on the withdrawal from mechanical ventilation and the length of stay in septic patients*

OBJECTIVES

No previous study has demonstrated whether critical illness polyneuropathy itself lengthens mechanical ventilation or whether this prolonged duration of ventilatory support is explained by concomitant risk factors for weaning failure. Our objectives were to evaluate the impact of critical illness polyneuropathy on the length of mechanical ventilation after controlling for coexisting risk factors for weaning failure and to assess the impact of critical illness polyneuropathy on the length of the stay in a cohort of septic patients.

DESIGN

Prospective cohort study.

SETTING

Intensive care unit of a tertiary hospital.

PATIENTS

All patients with severe sepsis or septic shock who required mechanical ventilation for > or =7 days who were considered ready to discontinue mechanical ventilation.

INTERVENTIONS

Patients underwent a neurophysiologic evaluation at onset of weaning from mechanical ventilation.

MEASUREMENTS AND MAIN RESULTS

Sixty-four critically ill septic patients were enrolled, and 34 developed critical illness polyneuropathy (53.1%; 95% confidence interval, 40.2-65.7%). Length of mechanical ventilation was significantly higher in patients who had developed critical illness polyneuropathy (median 34 days vs. 14 days, p < .001). The duration of the weaning period was also significantly greater in patients with critical illness polyneuropathy (median 15 days vs. 2 days, p < .001) even though factors suspected to influence the weaning process did not differ between these two groups. Multiple logistic regression analysis indicated that critical illness polyneuropathy was the only risk factor independently associated with weaning failure (odds ratio, 15.4; 95% confidence interval, 4.55, 52.3; p < .001). Lengths of intensive care unit and hospital stays were significantly higher in patients with critical illness polyneuropathy.

CONCLUSIONS

In critically ill septic patients, critical illness polyneuropathy significantly increases the duration of mechanical ventilation and prolongs the lengths of intensive care unit and hospital stays.

An educational intervention to reduce ventilator-associated pneumonia in an integrated health system: a comparison of effects

STUDY OBJECTIVES

To determine whether an educational initiative could decrease rates of ventilator-associated pneumonia in a regional health-care system.

SETTING

Two teaching hospitals (one adult, one pediatric) and two community hospitals in an integrated health system.

DESIGN

Preintervention and postintervention observational study.

PATIENTS

Patients admitted to the four participating hospitals between January 1, 1999, and June 30, 2002, who acquired ventilator-associated pneumonia.

INTERVENTION

An educational program for respiratory care practitioners and ICU nurses emphasizing correct practices for the prevention of ventilator-associated pneumonia. The program included a self-study module on risk factors for, and strategies to prevent, ventilator-associated pneumonia and education-based in-services. Fact sheets and posters reinforcing the information were posted throughout the ICU and respiratory care departments.

MEASUREMENTS AND RESULTS

Completion rates for the module were calculated by job title at each hospital. Rates of ventilator-associated pneumonia per 1,000 ventilator days were calculated for all hospitals combined and for each hospital separately. Overall 635 of 792 ICU nurses (80.1%) and 215 of 239 respiratory therapists (89.9%) completed the study module. There were 874 episodes of ventilator-associated pneumonia at the four hospitals during the 3.5-year study period out of 129,527 ventilator days. Ventilator-associated pneumonia rates for all four hospitals combined dropped by 46%, from 8.75/1,000 ventilator days in the year prior to the intervention to 4.74/1,000 ventilator days in the 18 months following the intervention (p < 0.001). Statistically significant decreased rates were observed at the pediatric hospital and at two of the three adult hospitals. No change in rates was seen at the community hospital with the lowest rate of study module completion among respiratory therapists (56%).

CONCLUSIONS

Educational interventions can be associated with decreased rates of ventilator-associated pneumonia in the ICU setting. The involvement of respiratory therapy staff in addition to ICU nurses is important for the success of educational programs aimed at the prevention of ventilator-associated pneumonia.

[Diagnostic value of quantitative cultures of endotracheal aspirate in ventilator-associated pneumonia: a multicenter study]

OBJECTIVE

To study the validity of quantitative cultures of tracheal aspirate (TA) in comparison with the plugged telescoping catheter (PTC) for the diagnosis of mechanical ventilator-associated pneumonia.

METHOD

Prospective multicenter study enrolling patients undergoing mechanical ventilation for longer than 72 hours. TA samples were collected from patients with suspected ventilator-associated pneumonia, followed by PTC sampling. Quantitative cultures were performed on all samples. Patients were classified according to the presence or not of pneumonia, based on clinical and radiologic criteria, clinical course and autopsy findings. The cutoff points were > or = 103 colony-forming units (cfu)/mL for PTC cultures; the TA cutoffs analyzed were > or = 105 and > or = 106 cfu/mL.

RESULTS

Of the 120 patients studied, 84 had diagnoses of pneumonia and 36 did not (controls). The sensitivity values for TA > or = 106, TA > or = 105, and PTC, respectively, were 54% (95% confidence interval [CI], 42%-64%), 71% (95% CI, 60%-81%), and 68% (95% CI, 57%-78%). The specificity values were 75% (95% CI, 58%-88%), 58% (95% CI, 41%-74%), and 75% (95% CI, 58%-88%), respectively. Staphylococcus aureus was the microorganism most frequently isolated in both TA and PTC samples, followed in frequency by Pseudomomonas aeruginosa in TA samples and Haemophilus influenzae in PTC samples. No significant differences were found between the sensitivity of TA > or = 105 and that of PTC, nor between the specificities of TA > or = 106 and PTC.

CONCLUSIONS

No differences in the specificities of PTC and TA were found when a TA cutoff of > or = 106 cfu/ml was used. Moreover, at a cutoff of > or = 105 the sensitivity of TA was not statistically different from that of PTC. Quantitative cultures of TA can be considered acceptable for the diagnosis of ventilator-associated pneumonia.

The closed tracheal suction catheter: 24 hour or 48 hour change?

Closed suction catheters (CSC) for removal of bronchial secretions in intubated patients have been used in intensive care units (ICU) for many years. Manufacturers still recommend daily changes of the catheter in order to reduce the incidence of ventilator associated pneumonia (VAP). There is, however, a lack of clinical evidence to support this recommendation. The objective of this study was therefore to compare the incidence of VAP in patients who receive either 24 hourly or 48 hourly changes of the CSC. Eligible patients were randomised to one of the two groups to receive either a 24 hourly change (n = 53) or a 48 hourly change (n = 48) of the CSC. Sputum specimens were sent second daily for quantitative culture. Chest x-rays (CXR) and white blood cell counts were attended daily. A VAP was diagnosed according to previously established criteria. A second set of modified criteria were also used to conduct a further analysis of the results. Of the 158 patients randomised, 101 completed the study. These patients had a mean age of 65 years and a mean APACHE II score of 28.2 in the first 24 hours of the study. The average duration in the trial was 10 days. The two groups were comparable in terms of demographic features. There were no reported cases of VAP in either group using the criteria originally selected in the study design. Using a modified criteria to diagnose VAP there were 10 (19%) patients with VAP in the 24 hour group and 13 (27%) in the 48 hour group. The incidence of VAP between the two groups was not statistically different (p = 0.35). To conclude, there was no difference in the incidence of VAP between the two groups studied. Based on previous studies conducted by Quirke and Kollef and the experience of our study we have changed our clinical practice to a 48 hour change of the CSC. We would, however, suggest further study or a meta-analysis of the available literature before a recommendation is made.

Bronchoalveolar interleukin-1 beta: a marker of bacterial burden in mechanically ventilated patients with community-acquired pneumonia

OBJECTIVE

To assess the relationship between concentrations of bronchoalveolar cytokines and bacterial burden (quantitative bacterial count) in intubated patients with a presumptive diagnosis of community-acquired pneumonia.

DESIGN

A cross-sectional and clinical investigation. SETTING Medical/surgical and respiratory intensive care unit of a tertiary 1,200-bed medical center.

PATIENTS

According to the time course of community-acquired pneumonia at the time of study with bronchoalveolar lavage, 69 mechanically ventilated patients were divided into three subgroups: primary (n = 11), referral (n = 23), and treated (n = 35) community-acquired pneumonia.

INTERVENTIONS

Bronchoalveolar lavage was performed in the most abnormal area on chest radiograph by fiberoptic bronchoscope. Bronchoalveolar lavage fluid was processed for quantitative bacterial culture. The concentrations of bronchoalveolar lavage cytokines (tumor necrosis factor-alpha, interleukin-1 beta, interleukin-6, interleukin-8, and interleukin-10) also were measured.

MEASUREMENTS AND MAIN RESULTS

Thirty-two patients had a positive bacterial culture (bronchoalveolar lavage > or = 10 colony-forming units/mL)., and made up 76% of pathogens recovered at high concentrations. The concentrations of bronchoalveolar lavage interleukin-1 beta were 199.1 +/- 32.1 and 54.9 +/- 13.0 pg/mL (mean +/- se) in the patients with positive and negative bacterial culture, respectively (p < .001). Bronchoalveolar lavage interleukin- 1 beta was significantly higher in the patients with a high bacterial burden (p < .001), with mixed bacterial infection (p < .001), and with pneumonia (p < .001), compared with values in patients without these features. The relationship between bacterial load and concentrations of bronchoalveolar lavage interleukin-1 beta was very strong in the patients with primary and referral community-acquired pneumonia but was borderline in treated community-acquired pneumonia.

CONCLUSIONS

The common pathogens were similar to the core pathogens of hospital-acquired pneumonia, probably due to antibiotic effects, delayed sampling, and superimposed nosocomial infection. Since the concentration of bronchoalveolar lavage interleukin-1 beta was correlated with bacterial burden in the alveoli, it may be a marker for progressive and ongoing inflammation in patients who have not responded to pneumonia therapy and who have persistence of bacteria in the lung.

Effect of an education program aimed at reducing the occurrence of ventilator-associated pneumonia

OBJECTIVE

The purpose of the study was to determine whether an education initiative could decrease the hospital rate of ventilator-associated pneumonia.

DESIGN

Pre- and postintervention observational study.

SETTING

Five intensive care units in Barnes-Jewish Hospital, an urban teaching hospital.

PATIENTS

Patients requiring mechanical ventilation who developed ventilator-associated pneumonia between October 1, 1999, and September 30, 2001.

INTERVENTIONS

An education program directed toward respiratory care practitioners and intensive care unit nurses was developed by a multidisciplinary task force to highlight correct practices for the prevention of ventilator-associated pneumonia. The program consisted of a ten-page self-study module on risk factors and practice modifications involved in ventilator-associated pneumonia, inservices at staff meetings, and formal didactic lectures. Each participant was required to take a preintervention test before the study module and identical postintervention tests following completion of the study module. Fact sheets and posters reinforcing the information in the study module were also posted throughout the intensive care units and the Department of Respiratory Care Services.

MEASUREMENTS AND MAIN RESULTS

One hundred ninety-one episodes of ventilator-associated pneumonia occurred in 15,094 ventilator days (12.6 per 1,000 ventilator days) in the 12 months before the intervention. Following implementation of the education module, the rate of ventilator-associated pneumonia decreased to 81 episodes in 14,171 ventilator days (5.7 per 1,000 ventilator days), a decrease of 57.6% (p <.001). The estimated cost savings secondary to the decreased rate of ventilator-associated pneumonia for the 12 months following the intervention were between $425,606 and $4.05 million.

CONCLUSIONS

A focused education intervention can dramatically decrease the incidence of ventilator-associated pneumonia. Education programs should be more widely employed for infection control in the intensive care unit setting and can lead to substantial decreases in cost and patient morbidity attributed to hospital-acquired infections.

Diagnosis of pneumonia and monitoring of infection eradication

Pneumonia can be classified as community-acquired (CAP) or hospital-acquired (nosocomial). Both are frequent infections that demand a great amount of medical resources. The diagnosis of CAP is based on clinical signs and the presence of a pulmonary infiltrate visible on chest radiograph. For practical purposes, CAP has been classified as typical, with an acute onset in which the most representative microorganism is Streptococccus pneumoniae, and atypical, with a subacute onset (Mycoplasma pneumoniae). Nevertheless, so far no studies have clearly demonstrated the utility of this classification in predicting the aetiology. Guidelines on CAP recommend associating the aetiology of CAP with comorbidity, age and severity. The microbiological diagnosis relies mainly on Gram stain and sputum culture, but this technique has disadvantages such as frequent contamination of the sample with oropharyngeal commensal flora, frequent sterile cultures associated with previous antibiotic treatment, and the fact that approximately 40% of patients are not able to expectorate. Other diagnostic techniques such as blood cultures, serological tests and fibreoptic bronchoscopy must be reserved for patients who are hospitalised, especially if they need admission to an intensive care unit. Compared with CAP, nosocomial pneumonia has major diagnostic problems due to the presence of other diseases able to mimic pneumonia and frequent bacterial colonisation of the lower respiratory tract. Most of the diagnostic techniques produce a high percentage of false-negative and false-positive results. This is especially true for ventilator-associated pneumonia. There is controversy over using a comprehensive aetiological work-up based on bronchoscopic techniques or only on quantitative culture of endotracheal aspiration. By contrast, there is consensus about the importance of the adequacy of empirical antibiotic treatment, since mortality rates are higher in patients who are inadequately treated. Once treatment of pneumonia has begun, it must be maintained for 48 to 72 hours because this is the minimum time to evaluate a clinical response. Antibacterial agents have to be adjusted according to microbiological findings. In nonresponding patients, pneumonia-related complications and the presence of multiresistant micro-organisms or non-covered pathogens must be ruled out.

Pulmonary Infections in Ventilated Patients: Diagnostic and Therapeutic Options

The diagnosis of pulmonary infections in the ventilated patient has threatened the foundations of medicine. Although the lifesaving techniques of endotracheal intubation (developed for the treatment of diphtheria) and artificial ventilation (developed for the management of poliomyelitis) contribute greatly to medical care, they have resulted in the production of the "progress"-related infection of ventilator-associated pneumonia (VAP). Modern ventilator therapy is a substantial technologic advance from earlier days and, as technology inherently does, has removed some of the human element, the main foundation of Oslerian medical practice. The time-honored clinical diagnosis based on physical examination by an experienced physician has been seriously compromised in the approach to VAP.

Nosocomial pneumonia in patients undergoing heart surgery

OBJECTIVE

To determine the risk factors related to the presence of postsurgical nosocomial pneumonia (NP) in patients who had undergone cardiac surgery.

DESIGN

A case-control study.

SETTING

Postcardiac surgical intensive care unit at a university center.

PATIENTS

A total of 45 patients with NP and 90 control patients collected during a 4-yr period.

INTERVENTIONS

Pre-, intra-, and postoperative factors were collected and compared between two groups of patients (cases vs. controls) to determine their influence on the development of NP. The diagnosis of NP was always microbiologically confirmed as pulmonary specimen brush culture of > or =10(3) colony-forming units/mL or positive blood culture/pleural fluid culture by the growth of identical microorganisms isolated at the lung. For each patient diagnosed with NP, we selected control cases at a ratio of 1:2.

MEASUREMENTS AND MAIN RESULTS

The incidence of NP was 6.5%. Multivariate analysis found a probable association of the following variables with a greater risk for the development of NP: reintubation (adjusted odds ratio [AOR], 62.5; 95% confidence interval [CI], 8.1-480; p = .01); nasogastric tube (AOR, 19.7; 95% CI, 3.5-109; p = .01), transfusion of > or =4 units of blood derivatives (AOR, 12.8; 95% CI, 2-82; p = .01) and empirical treatment with broad-spectrum antibiotics (AOR, 6.6; 95% CI, 1.2-36.8; p = .02). Culture results showed 13.3% of the NP to be of polymicrobial origin, whereas 77.3% of the microorganisms isolated were Gram-negative bacteria. The mortality (51 vs. 6.7%, p < .01) and the length of stay in the intensive care unit (25+/-14.8 days vs. 5+/-5 days, p < .01) were both greater in patients with NP.

CONCLUSIONS

We conclude that the surgical risk factors, except the transfusion of blood derivatives, have little effect on the development of NP. Reintubation, nasogastric tubing, previous therapy with broad-spectrum antibiotics, and blood transfusion are factors most likely associated with NP acquisition.

Mortality and the increase in length of stay attributable to the acquisition of Acinetobacter in critically ill patients

OBJECTIVE

To determine the impact of Acinetobacter baumannii (AB) acquisition in intensive care unit (ICU) patients on mortality and length of stay (LOS).

DESIGN

Pairwise matched 1:1 case-control study.

SETTING

Medical-surgical ICU in a tertiary health care institution.

PATIENTS

During 16 months, all patients admitted to the ICU were eligible. Case patients were defined as every patient with an AB isolation 48 hrs after ICU admission. Control patients were retrospectively selected from ICU patients without any AB isolation, according to seven matching variables.

MEASUREMENTS AND MAIN RESULTS

Attributable mortality and excess LOS in the ICU were measured. Eighty-seven patients were included, with 75 pairs successfully matched. Infection was defined in 48 patients (23 respiratory). The attributable mortality rate for AB acquisition was 30% (49% vs.19%) (95% confidence interval [CI] = 23%, 37%): 43% (CI = 34%, 52%) in patients with infection (58% vs.15%) and 53% (CI = 41%, 65%) in patients with respiratory infections (70% vs.17%). The estimated risk rates for death were 2.6 (CI = 1.6, 4.5; p < .001), 4.0 (CI = 1.9, 8.3; p < .001), and 4.0 (CI = 1.6, 10.2; p < .01), respectively. The attributable excess LOS was 13 days for both AB acquisition and infection (23 vs. 10 days; p < .001) and respiratory infections (23 vs. 10 days; p < .01). In noninfected patients, no significant excess of mortality was found (33% vs. 26%), but LOS increased in 15 days.

CONCLUSION

AB acquisition involved an excess LOS in ICU patients and increased risk of death, but the latter could be found only in patients with proven infection.

Fiberoptic bronchoscopy in coronary care unit patients: indications, safety, and clinical implications

STUDY OBJECTIVES

To evaluate the indications, safety, therapeutic impact, and outcome of fiberoptic bronchoscopy (FOB) in coronary care unit (CCU) patients.

DESIGN

Retrospective review of all CCU patients undergoing FOB during a 6-year period.

SETTING

Tertiary care university hospital.

RESULTS

Among 8,330 patients admitted to the CCU; 40 (0.5%) patients underwent FOB to evaluate pulmonary abnormalities, most often (78%) to appraise clinically suspected pneumonia. Thirty-five (88%) patients were intubated and 21 (53%) had acute myocardial infarction (MI) before FOB. There were two major complications (bleeding, intubation) occurring within 24 h of FOB, one of which appeared due to the procedure. No episodes of chest pain or ischemic events were recorded and no significant increase in major complications was noted in MI patients (3% vs 5%). Patients having FOB within 10 days of MI had higher survival (79%) than those undergoing FOB later (29%) (p = 0.05). Seven different bacterial pathogens were isolated in 6 (15%) patients, probably reflecting prior empiric antibiotics in 32 (80%) patients. Therapy was changed in 64% of patients in whom a potential pathogen was identified. Despite alterations in treatment, patients with clinically suspected pneumonia and any organisms isolated by FOB had greater mortality (79% vs 31%, p = 0.003) than those with sterile FOB cultures.

CONCLUSION

FOB may be diagnostically useful in the evaluation of pulmonary abnormalities in selected patients with acute cardiac disease, can be performed safely, and may influence management decisions. Positive bronchoscopy cultures often influence therapy but are associated with higher mortality, suggesting a lethal effect of nosocomial pneumonia in this subset of CCU patients. The risks of FOB must be weighed with the impact of FOB results on patient outcome, and its role requires further investigation.

Impact of tracheotomy on colonization and infection of lower airways in children requiring long-term ventilation: a prospective observational cohort study

STUDY OBJECTIVES

Determination of the following: (1) colonization and infection rates in children requiring long-term ventilation initially via a transtracheal tube and subsequently via a tracheotomy; (2) the number of infection episodes per 1,000 ventilation days, during both types of artificial airways; and (3) routes of colonization/infection of the lower airways, ie, whether the pathogenesis was endogenous (via the oropharynx) or exogenous (via the transtracheal tube or tracheotomy).

DESIGN

Observational, cohort, prospective study over 2 1/2 years.

SETTING

Pediatric ICU (PICU), Royal Liverpool Children's National Health Service Trust of Alder Hey, a tertiary referral center.

PATIENTS

Twenty-two children requiring long-term mechanical ventilation initially transtracheally and subsequently via a tracheotomy.

INTERVENTION

Nil.

RESULTS

The lower airways were colonized in 71% of children during transtracheal ventilation; posttracheotomy, this was 95% (p=0.03). Children developed significantly fewer infections following colonization with a microorganism posttracheotomy (8/15 pretracheotomy vs 6/21 posttracheotomy; p=0.013). Throughout the study, there were a total of 17 episodes of infection, all of which were preceded by colonization. Haemophilus influenzae, Staphylococcus aureus, Acinetobacter baumannii, and Pseudomonas aeruginosa were the same four causative pathogens during mechanical ventilation both transtracheally and via tracheotomy. Forty-nine episodes of colonization were observed, 15 pretracheotomy and 34 posttracheotomy; of these, 12 (80%) and 19 episodes (56%), respectively, were primary endogenous, ie, present in the oropharynx on hospital admission and subsequently at tracheotomy. Only one colonization episode (7%) of exogenous pathogenesis was observed during transtracheal intubation, while 12 (35%) (p=0.02) occurred after tracheotomy. An equal number of secondary endogenous colonization episodes (two and three, ie, acquired in the oropharynx after PICU admission and after tracheotomy, respectively, were recorded.

CONCLUSIONS

(1) Despite a high level of hygiene, exogenous colonization without subsequent infection was common. (2) Although all patients were colonized, the infection rate was lower after tracheotomy. This may be due to enhanced immunity (medically stable) and improved tracheobronchial toilet. (3) Microorganisms in children with tracheotomy differ from those in adults.

Use of bronchoalveolar lavage semiquantitative cultures in cystic fibrosis

To assess bronchoalveolar lavage (BAL) in adult CF patients with respiratory symptoms, we studied BAL fluid (BALF) culture results from 28 bronchoscopies in 11 patients. Patients were asked to provide sputum for culture. All but two patients were receiving antibiotics at the time of bronchoscopy, with 13 bronchoscopies done on patients who had been receiving antibiotics for more than 10 d. Gram stain of the BALF was positive in 18 cases. In all but one BALF, > 10,000 colony-forming units per milliliter (cfu/ml) BALF of one or more pathogens was identified. The final case grew Burkholderia cepacia, which was not grown in the sputum. In only six cases (21%) were the sputum and BALF culture results the same. Prior to 11 bronchoscopies, the sputum was not adequate. The remaining 11 cases either had different pathogens in the BAL (six cases), or had some but not all of the BALF pathogens in the sputum. BALF cultures changed therapy in 13 (48%) of cases. Semiquantitative culture of BALF was a useful diagnostic tool in CF in patients in whom empiric therapy failed.

Complications of mechanical ventilation. A bedside approach

Instead of cataloging complications reported to occur during mechanical ventilation, the authors have discussed the potential causes for several common scenarios in the management of ventilated patients. These include the new development of hypotension, acute respiratory distress (fighting the ventilator), repeated sounding of the ventilator's high-pressure alarm, hypoxemia, blood from the endotracheal tube, and the problem of diagnosing VAP. In the course of considering likely explanations for this group of circumstances for which the clinician is consulted or called to the bedside, virtually all reported ventilator-associated complications must be discussed. This new approach to an important aspect of ICU care may aid in clinical problem-solving and reduce the likelihood that a diagnosis will be missed or inappropriate measures taken in the absence of a systematic, pathophysiology-based approach.

Prospective evaluation of a semiquantitative dip slide method compared with quantitative bacterial cultures of BAL fluid

BACKGROUND

Quantitative bacteriologic workup of BAL fluid (BALF) has evolved as a sensitive and specific technique for the diagnosis of bacterial pneumonia. Conventional quantitative cultures are expensive, time-consuming, and often unavailable on a 24-h basis. Therefore, we evaluated a dip slide method for the semiquantitative measurement of bacterial cultures in BALF specimens and compared the results with those from conventional quantitative cultures.

METHODS

Fifty BALF specimens from 45 patients with suspected pulmonary infection were examined prospectively with both methods. We compared the microbiologic results of conventional quantitative cultures with those of the dip slide method that is commercially available for blood cultures. Cost-effectiveness analysis of both methods was performed.

RESULTS

In 37 BALF specimens, 64 bacterial strains were detected with both techniques. The dip slide method and conventional cultures showed a high correlation with respect to the colony counts of the individual organisms per milliliter BALF (r=0.935; p= 0.0001) and the sum of colony counts in individual patients (r=0.947; p=0.0001). Although five strains were not detected by the dip slide technique, the diagnostic accuracy was not influenced. In 13 BALF samples, there was no growth of bacteria with both techniques. While the diagnostic yield of both methods was similar, the dip slide technique was 44 to 66% less expensive than conventional cultures.

CONCLUSIONS

The examination of BALF with a clip slide method is highly comparable to conventional quantitative culture techniques, less expensive, and can be used independently of a specialized microbiology laboratory on a 24-h basis.