Probable Ventilator-associated Pneumonia Research Articles

Increasing rates of ventilator-associated events: Blame it on COVID-19?

Background: Rates of ventilator-associated events (VAEs), including infection-related ventilator-associated complications (IVACs) and probable ventilator-associated pneumonia (PVAPs) have increased nationwide since the onset of the COVID-19 pandemic. In December 2021, our health system adopted a new electronic medical record (EMR), which changed the way surveillance for VAEs is performed. We reviewed surveillance criteria, COVID-19 status, and culturing practices in attempts to understand why VAE rates continue to be elevated. Methods: We collected data on VAE type, culture data, COVID-19 status, and surveillance criteria for all patients meeting NHSN definitions for VAE from 2018 through November 2022. For all patients in 2022 (post-EMR transition), 2 physicians (A.D. and M.D.) manually reviewed documented ventilator settings from flow sheets to validate the automated EMR data, and they evaluated culture data for appropriateness. Cultures were defined as appropriate unless they were included in “pancultures” for leukocytosis without concern for pneumonia documented. Rates were compared using an interrupted time series (ITS) analysis before and after the onset of the COVID-19 pandemic and the EMR transition. Patient level data were compared across periods using the χ2 test. All analyses were performed using SAS version 9.4 software. Results: COVID-19 has been implicated in the increasing number of VAEs since the pandemic began: 6% of patients in 2020, 18% in 2021, and 23% in 2022 (P < .001). The percentage of patients meeting criteria for VAE by positive end-expiratory pressure (PEEP) decreased from 2018 to 2022 (92%, 95%, 93%, 85%, 85%, respectively; P = .0004). Patients meeting criteria for VAE by fraction of inspired oxygen (FiO2) increased from 2018 to 2022 (9%, 6%, 11%, 17%, 19%, respectively; P = .0002). Manual review of 2022 data indicated opportunities for test stewardship in 8 of 65 patients with cultures (12%). ITS analysis revealed that IVAC+ rates were climbing prior to the onset of the COVID-19 pandemic (Fig. 1). We observed a marked increase in rates with the implementation of our new EMR and the changes to our surveillance process (0.32 cases per 100 ventilator days). Manual review of records from 2022 revealed 5 patients in which documentation of ventilator settings to meet VAE diagnosis could not be retrieved from flow sheets. Conclusions: COVID-19 continues to affect VAE despite vaccine availability and may partially account for elevated rates nationwide. However, changes in EMR-automated VAE surveillance may also affect rates. Our findings suggest that automated surveillance captures transient or spurious changes in ventilator machine settings that do not accurately represent clinical status. These data may contribute to spurious increases in VAE. More studies are needed to better understand the impact of both COVID-19 and automated surveillance on VAE.Disclosures: None

Increased rates of secondary bacterial infections, including Enterococcus bacteremia, in patients hospitalized with coronavirus disease 2019 (COVID-19).

We compared the rates of hospital-onset secondary bacterial infections in patients with coronavirus disease 2019 (COVID-19) with rates in patients with influenza and controls, and we investigated reports of increased incidence of Enterococcus infections in patients with COVID-19. Retrospective cohort study. An academic quaternary-care hospital in San Francisco, California. Patients admitted between October 1, 2019, and October 1, 2020, with a positive SARS-CoV-2 PCR (N = 314) or influenza PCR (N = 82) within 2 weeks of admission were compared with inpatients without positive SARS-CoV-2 or influenza tests during the study period (N = 14,332). National Healthcare Safety Network definitions were used to identify infection-related ventilator-associated complications (IVACs), probable ventilator-associated pneumonia (PVAP), bloodstream infections (BSIs), and catheter-associated urinary tract infections (CAUTIs). A multiple logistic regression model was used to control for likely confounders. COVID-19 patients had significantly higher rates of IVAC and PVAP compared to controls, with adjusted odds ratios of 4.7 (95% confidence interval [CI], 1.7-13.9) and 10.4 (95 % CI, 2.1-52.1), respectively. COVID-19 patients had higher incidence of BSI due to Enterococcus but not BSI generally, and whole-genome sequencing of Enterococcus isolates demonstrated that nosocomial transmission did not explain the increased rate. Subanalyses of patients admitted to the intensive care unit and patients who required mechanical ventilation revealed similar findings. COVID-19 is associated with an increased risk of IVAC, PVAP, and Enterococcus BSI compared with hospitalized controls, which is not fully explained by factors such as immunosuppressive treatments and duration of mechanical ventilation. The mechanism underlying increased rates of Enterococcus BSI in COVID-19 patients requires further investigation.

Two-State Collaborative Study of a Multifaceted Intervention to Decrease Ventilator-Associated Events.

Ventilator-associated events are associated with increased mortality, prolonged mechanical ventilation, and longer ICU stay. Given strong national interest in improving ventilated patient care, the National Institute of Health and Agency for Healthcare Research and Quality funded a two-state collaborative to reduce ventilator-associated events. We describe the collaborative's impact on ventilator-associated event rates in 56 ICUs. Longitudinal quasi-experimental study. Fifty-six ICUs at 38 hospitals in Maryland and Pennsylvania from October 2012 to March 2015. We organized a multifaceted intervention to improve adherence with evidence-based practices, unit teamwork, and safety culture. Evidence-based interventions promoted by the collaborative included head-of-bed elevation, use of subglottic secretion drainage endotracheal tubes, oral care, chlorhexidine mouth care, and daily spontaneous awakening and breathing trials. Each unit established a multidisciplinary quality improvement team. We coached teams to establish comprehensive unit-based safety programs through monthly teleconferences. Data were collected on rounds using a common tool and entered into a Web-based portal. ICUs reported 69,417 ventilated patient-days of intervention compliance observations and 1,022 unit-months of ventilator-associated event data. Compliance with all evidence-based interventions improved over the course of the collaborative. The quarterly mean ventilator-associated event rate significantly decreased from 7.34 to 4.58 cases per 1,000 ventilator-days after 24 months of implementation (p = 0.007). During the same time period, infection-related ventilator-associated complication and possible and probable ventilator-associated pneumonia rates decreased from 3.15 to 1.56 and 1.41 to 0.31 cases per 1,000 ventilator-days (p = 0.018, p = 0.012), respectively. A multifaceted intervention was associated with improved compliance with evidence-based interventions and decreases in ventilator-associated event, infection-related ventilator-associated complication, and probable ventilator-associated pneumonia. Our study is the largest to date affirming that best practices can prevent ventilator-associated events.

Prevention does not always improve patient outcomes—use of a ventilator associated events prevention bundle as a quality metric

Over the last decade, and particularly since the public reporting of the Center for Medicare and Medicaid Service’s (CMS) quality based performance evaluation of potentially preventable conditions in hospitalized patients, the incidence of ventilator associated pneumonia (VAP) has taken a sharp drop with several institutions in United States reporting a “zero incidence” (1). Lately this discrepancy between VAP rates among quality monitoring reports and the actual care given to patients has widened, and the accuracy of reporting zero VAP has been questioned. While the application of several infection prevention measures, implemented as a “bundled approach” ,with effective implementation, has been viewed to be an effective measure for decreasing the incidence of VAP, the credibility of these reports has been questioned (2-5). Recognizing the formidable challenge of accurately diagnosing VAP and the existing gaps between surveillance and clinical definitions, the Centers for Disease Control and Prevention (CDC) in 2013 shifted its focus to complications related to ventilation, rather than to identifying infection, through the new surveillance definition—ventilator associated events (VAE) (6). VAE includes ventilator-associated complications (VAC), infection-related ventilator-associated complications (IVAC), as well as possible and probable VAP (PVAP).

Does ventilator-associated event surveillance detect ventilator-associated pneumonia in intensive care units? A systematic review and meta-analysis.

BackgroundVentilator-associated event (VAE) is a new surveillance paradigm for monitoring complications in mechanically ventilated patients in intensive care units (ICUs). The National Healthcare Safety Network replaced traditional ventilator-associated pneumonia (VAP) surveillance with VAE surveillance in 2013. The objective of this study was to assess the consistency between VAE surveillance and traditional VAP surveillance.MethodsWe systematically searched electronic reference databases for articles describing VAE and VAP in ICUs. Pooled VAE prevalence, pooled estimates (sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV)) of VAE for the detection of VAP, and pooled estimates (weighted mean difference (WMD) and odds ratio ([OR)) of risk factors for VAE compared to VAP were calculated.ResultsFrom 2191 screened titles, 18 articles met our inclusion criteria, representing 61,489 patients receiving mechanical ventilation at ICUs in eight countries. The pooled prevalence rates of ventilator-associated conditions (VAC), infection-related VAC (IVAC), possible VAP, probable VAP, and traditional VAP were 13.8 %, 6.4 %, 1.1 %, 0.9 %, and 11.9 %, respectively. Pooled sensitivity and PPV of each VAE type for VAP detection did not exceed 50 %, while pooled specificity and NPV exceeded 80 %. Compared with VAP, pooled ORs of in-hospital death were 1.49 for VAC and 1.76 for IVAC; pooled WMDs of hospital length of stay were −4.27 days for VAC and −5.86 days for IVAC; and pooled WMDs of ventilation duration were −2.79 days for VAC and −2.89 days for IVAC.ConclusionsVAE surveillance missed many cases of VAP, and the population characteristics identified by the two surveillance paradigms differed. VAE surveillance does not accurately detect cases of traditional VAP in ICUs.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-016-1506-z) contains supplementary material, which is available to authorized users.

Central Nervous System Depressants Poisoning and Ventilator Associated Pneumonia: An Underrated Risk Factor at the Toxicological Intensive Care Unit.

Background:Ventilator-Associated Pneumonia (VAP) is the main cause of nosocomial infection at intensive care units (ICUs), which causes high mortality and morbidity.Objectives:The objective of the present survey was to identify the VAP risk and prognostic factors among poisoned patients, who were admitted to the toxicological ICU (TICU), especially central nervous system (CNS) depressants due to their prevalence and importance.Patients and Methods:A case-control study was conducted at the Loghman Hakim hospital between March 2013 and March 2014. Among 300 poisoned patients with mechanical ventilator ≥ 48 hours, 150 patients, who had developed microbiologically-confirmed VAP were considered as the VAP group and 150 without VAP were defined as the control group. The following data were collected; age, gender, type of poisoning, glasgow coma score, Acute physiology and chronic health evaluation (APACHE) II score, length of hospital stay, previous antibiotic use, microbial culture of the trachea, body temperature, leukocyte count, and patients’ outcome. Based on the type of poisoning, patients were divided into three groups including: opioid, CNS depressants and others. All data were expressed as means (SD) for continuous variables and frequencies for categorical variables. Logistic regression was used to determine the relationship between risk factors and VAP.Results:The mean age of the patients was 33.9 ± 14.3 years. The probable VAP incidence and mortality were 22% and 18.6%, respectively. The rate of CNS depressant versus opioid use (odds ratio, 3.74; P < 0.027), APACHE II (odds ratio, 1.28; P < 0.000) and length of hospital stay (odds ratio, 2.15; P < 0.000) were the independent risk factors for VAP. While, the APACHE II score (odds ratio, 1.12; P < 0.044) and length of hospital stay (odds ratio, 2.15; P < 0.000) were the independent predictors of VAP mortality among these patients. The most common microorganisms in VAP cases were Methicillin-Resistant Staphylococcus aureus (MRSA) and Acinetobacter sp. (56.7% and 12.7%, respectively).Conclusions:Central nervous system depressant was an important risk factor for VAP among poisoned patients. Hypoventilation due to CNS depression can lead to VAP. The APACHE II and length of hospital stay were shown as independent predictors of VAP and mortality among these patients.

Empirical antimicrobial therapy for probable v. directed therapy for possible ventilator-associated pneumonia in critically injured patients.

Ventilator-associated pneumonia (VAP) has recently been classified as possible or probable. Although direct attributable mortality has been difficult to prove, delay in instituting appropriate therapy has been reported to increase morbidity and mortality. Recent literature suggests that in possible VAP, instituting directed therapy while awaiting microbiological culture does not prejudice outcome compared with best-guess empirical therapy. To ascertain outcomes of directed v. empirical therapy in possible and probable VAP, respectively. Endotracheal aspirates were obtained from patients with suspected VAP. Those considered to have possible VAP were given directed therapy following culture results, whereas patients with more convincing evidence of VAP were classed as having probable VAP and commenced on empirical antimicrobials based on microbiological surveillance. Pneumonia was suspected in 106 (36.8%) of 288 patients admitted during January - December 2014. Of these, 13 did not fulfil the criteria for VAP. Of the remaining 93 (32.2%), 31 (33.3%) were considered to have probable and 62 (66.7%) possible VAP. The former were commenced on empirical antimicrobials, with 28 (90.3%) receiving appropriate therapy. Of those with possible VAP, 34 (54.8%) were given directed therapy and in 28 (45.2%) no antimicrobials were prescribed. Of the latter, 24 recovered without antimicrobials and 4 died, 3 from severe traumatic brain injury and 1 due to overwhelming intra-abdominal sepsis. No death was directly attributable to failure to treat VAP. No significant difference in mortality was found between the 34 patients with possible VAP who were commenced on directed therapy and the 31 with probable VAP who were commenced on empirical antimicrobials (p=0.75). Delaying antimicrobial therapy for VAP where clinical doubt exists does not adversely affect outcome. Furthermore, this policy limits the use of antimicrobials in patients with possible VAP following improvement in their clinical condition despite no therapy.

Impact of chlorhexidine mouthwash prophylaxis on probable ventilator-associated pneumonia in a surgical intensive care unit.

Background:Prevention of ventilator-associated pneumonia is a healthcare goal. Although data is inconsistent, some studies suggest that oral chlorhexidine may decrease rates of pneumonia in mechanically-ventilated patients. We sought to assess the rate of pneumonia in the Surgical Intensive Care Unit (SICU) pre and post implementation of routine chlorhexidine mouthwash prophylaxis.Materials and Methods:A retrospective cohort study was conducted, including patients between 1/1/2009 and 12/31/2009 who did not receive chlorhexidine mouthwash compared to patients that received prophylactic chlorhexidine mouthwash between 3/1/2010 and 2/28/2011. The primary outcome of the study was rate of probable ventilator-associated pneumonia (VAP) for the pre-chlorhexidine implementation cohort compared to post-implementation, using the 2013 Center for Disease Control definitions. Mechanically ventilated patients with respiratory cultures were screened for inclusion in the study. Secondary endpoints included duration of mechanical ventilation, in-hospital mortality, ICU and hospital length of stay. Statistical analysis was conducted by Fisher's exact test for nominal data and Mann-Whitney U test for continuous data.Results:A total of 1780 mechanically ventilated patients in the pre-chlorhexidine group and 1854 in the post-chlorhexidine group were screened for inclusion. Of the 601 mechanically ventilated patients that were further evaluated for inclusion; 158 patients (26.3%) had positive cultures and were included in the study (94 pre-group and 64 post-group). The rate of probable VAP was significantly decreased in the post-group compared to the pre-group (1.85% pre vs 0.81% post, P = 0.0082).Conclusion:Use of chlorhexidine mouthwash prophylaxis may reduce rates of probable VAP. Further study is warranted.

A Prospective Evaluation of Ventilator-Associated Conditions and Infection-Related Ventilator-Associated Conditions

The Centers for Disease Control and Prevention has shifted policy away from using ventilator-associated pneumonia (VAP) and toward using ventilator-associated conditions (VACs) as a marker of ICU quality. To date, limited prospective data regarding the incidence of VAC among medical and surgical ICU patients, the ability of VAC criteria to capture patients with VAP, and the potential clinical preventability of VACs are available. This study was a prospective 12-month cohort study (January 2013 to December 2013). We prospectively surveyed 1,209 patients ventilated for ≥ 2 calendar days. Sixty-seven VACs were identified (5.5%), of which 34 (50.7%) were classified as an infection-related VAC (IVAC) with corresponding rates of 7.0 and 3.6 per 1,000 ventilator days, respectively. The mortality rate of patients having a VAC was significantly greater than that of patients without a VAC (65.7% vs 14.4%, P < .001). The most common causes of VACs included IVACs (50.7%), ARDS (16.4%), pulmonary edema (14.9%), and atelectasis (9.0%). Among IVACs, 44.1% were probable VAP and 17.6% were possible VAP. Twenty-five VACs (37.3%) were adjudicated to represent potentially preventable events. Eighty-six episodes of VAP occurred in 84 patients (10.0 of 1,000 ventilator days) during the study period. The sensitivity of the VAC criteria for the detection of VAP was 25.9% (95% CI, 16.7%-34.5%). Although relatively uncommon, VACs are associated with greater mortality and morbidity when they occur. Most VACs represent nonpreventable events, and the VAC criteria capture a minority of VAP episodes.

Differences between novel and conventional surveillance paradigms of ventilator-associated pneumonia

To investigate the concordance between novel and conventional surveillance paradigms for ventilator-associated pneumonia (VAP). This study was conducted at a regional teaching hospital in southern Taiwan with 5 acute intensive care units. To assess the validity of novel ventilator-associated event (VAE) surveillance, we retrospectively applied the VAE algorithm to analyze all VAP cases that were identified using conventional definitions between April 2010 and February 2014. Patient outcomes, including ventilator days, hospital stay lengths, and in-hospital mortality were recorded. Among 165 episodes of conventional VAP, 55 (33.3%), 40 (24.2%), 20 (12.1%), and 2 (1.2%) episodes were classified as a ventilator-associated condition, an infection-related ventilator-associated complication, possible VAP, and probable VAP, respectively, according to the new VAE algorithm. Changes in positive end-expiratory pressure and inspired oxygen fraction levels during the development of VAP were significant higher among each VAE category than for conventional VAP (all P < .001). In-hospital mortality was significantly higher among patients with ventilator-associated condition than for patients with conventional VAP (P = .0185). In our study population, novel VAE surveillance only detected one-third of conventional VAP cases. Thus, more studies are needed to further validate VAE surveillance compared with conventional VAP by using strong microbiologic criteria, particularly bronchoalveolar lavage with a protected specimen brush for diagnosing VAP.

Applicability of the National Healthcare Safety Network's surveillance definition of ventilator-associated events in the surgical intensive care unit: a 1-year review.

In 2012, the National Healthcare Safety Network presented a new surveillance definition for ventilator-associated events (VAEs) to objectively define worsening pulmonary status in ventilated patients. VAE subcategories, ventilator-associated condition (VAC), infection-related VAC, and probable ventilator-associated pneumonia (PrVAP), were vetted predominantly in medical intensive care units. Our goal was to evaluate how well VAE criteria characterize pulmonary complications in surgical intensive care unit (SICU) patients. Since September 2012, all intubated SICU patients were screened prospectively for VAE and monitored for sustained respiratory dysfunction that did not meet VAE criteria. We diagnosed ventilator-associated pneumonia (VAP) using a clinical definition: Clinical Pulmonary Infection Score (CPIS) greater than 6 and catheter-directed bronchoalveolar lavage cultures with 10 or more colony-forming units per milliliter of pathogenic organisms. We admitted 704 intubated patients. A total of 437 were intubated for two or more days (mean [SD], age 46 [18] years; 65% male; median ventilator days, 4 [range, 2-9]; median Sequential Organ Failure Assessment [SOFA] score, 8 [range, 5-10]). Using VAE criteria, we identified 37 patients with VAC, 31 with infection-related VAC, and 22 with PrVAP. While the remaining 400 patients did not meet VAE criteria, we identified 111 patients (28%) with respiratory deterioration and diagnosed 99 additional pneumonias. Of the 111 patients, 85 (77%) never had a period of stable/decreasing oxygenation, requiring elevated vent settings upon initiation of ventilation preventing them from meeting VAE criteria. Of the 99 pneumonia patients, 10% had sustained respiratory deterioration treated with elevations in mean airway pressure; they did not meet VAE criteria as the positive end-expiratory pressure or FIO2 was not elevated. Twenty-seven percent never had a period of stable/decreasing oxygenation. Fifty-eight percent had less than 2 days of respiratory deterioration. Agreement between PrVAP and clinical VAP was 77.3% (κ = 0.243, p < 0.001). The applicability of the new National Healthcare Safety Network categories of VAE to critically ill surgery patients is limited. Agreement between PrVAP and clinical VAP in SICU patients is poor. Most surgical patients are not well categorized by this new definition; a better method of surveillance should be created for this patient population. Diagnostic study, level III.

Prevalence and test characteristics of national health safety network ventilator-associated events.

The primary aim of the study was to measure the test characteristics of the National Health Safety Network ventilator-associated event/ventilator-associated condition constructs for detecting ventilator-associated pneumonia. Its secondary aims were to report the clinical features of patients with National Health Safety Network ventilator-associated event/ventilator-associated condition, measure costs of surveillance, and its susceptibility to manipulation. Prospective cohort study. Two inpatient campuses of an academic medical center. Eight thousand four hundred eight mechanically ventilated adults discharged from an ICU. None. The National Health Safety Network ventilator-associated event/ventilator-associated condition constructs detected less than a third of ventilator-associated pneumonia cases with a sensitivity of 0.325 and a positive predictive value of 0.07. Most National Health Safety Network ventilator-associated event/ventilator-associated condition cases (93%) did not have ventilator-associated pneumonia or other hospital-acquired complications; 71% met the definition for acute respiratory distress syndrome. Similarly, most patients with National Health Safety Network probable ventilator-associated pneumonia did not have ventilator-associated pneumonia because radiographic criteria were not met. National Health Safety Network ventilator-associated event/ventilator-associated condition rates were reduced 93% by an unsophisticated manipulation of ventilator management protocols. The National Health Safety Network ventilator-associated event/ventilator-associated condition constructs failed to detect many patients who had ventilator-associated pneumonia, detected many cases that did not have a hospital complication, and were susceptible to manipulation. National Health Safety Network ventilator-associated event/ventilator-associated condition surveillance did not perform as well as ventilator-associated pneumonia surveillance and had several undesirable characteristics.

Improving ventilator-associated event surveillance in the National Healthcare Safety Network and addressing knowledge gaps: update and review.

The Centers for Disease Control and Prevention (CDC) recently transitioned from ventilator-associated pneumonia (VAP) surveillance to ventilator-associated event (VAE) surveillance in adult inpatient settings. Since the transition, several modifications have been made to improve surveillance methods, and there is a growing body of data regarding the epidemiology, risk factors, and preventability of VAEs. The VAE surveillance definition algorithm is based on objective criteria and includes three tiers: ventilator-associated conditions, infection-related ventilator-associated complications, and possible and probable VAP. VAE surveillance expands the purview of surveillance beyond pneumonia alone to include additional complications of mechanical ventilation. Most VAEs are caused by pneumonia, pulmonary edema, atelectasis, or acute respiratory distress syndrome. VAEs are associated with adverse outcomes including prolonged mechanical ventilation, longer intensive care and hospital length-of-stay, and higher mortality rates. Studies to date suggest that minimizing sedation and optimizing fluid management can reduce VAE rates. We review the CDC's recent updates on VAE surveillance definitions, methods, and tools, and provide an overview of the growing evidence base for VAE as a patient safety measure. Further work is needed to affirm and extend the current knowledge about how best to prevent VAEs.

A More Clinically Relevant Model of Ventilator-associated Pneumonia?

A More Clinically Relevant Model of Ventilator-associated Pneumonia?

Surveillance and evaluation of ventilator-associated events as per Centers for Disease Control and Prevention guidelines

While ventilator-associated pneumonia (VAP) can affect all patients ventilated for >2 days in an ICU, an issue during the last two decades has been identification of a universally accepted definition. The Centers for Disease Control and Prevention (CDC) in Atlanta, GA, USA, have designed a new surveillance paradigm aiming to increase the objectivity of VAE diagnosis ranging from ventilator-associated condition (VAC), infective VAC to possible and probable VAP [1]. We assessed the feasibility and accessibility of the audit tool developed from the CDC guidelines as a marker of quality assurance.

Developing a New, National Approach to Surveillance for Ventilator-Associated Events*

To develop and implement an objective, reliable approach to surveillance for ventilator-associated events in adult patients. The Centers for Disease Control and Prevention (CDC) convened a Ventilator-Associated Pneumonia (VAP) Surveillance Definition Working Group in September 2011. Working Group members included representatives of stakeholder societies and organizations and federal partners. The Working Group finalized a three-tier, adult surveillance definition algorithm for ventilator-associated events. The algorithm uses objective, readily available data elements and can identify a broad range of conditions and complications occurring in mechanically ventilated adult patients, including but not limited to VAP. The first tier definition, ventilator-associated condition (VAC), identifies patients with a period of sustained respiratory deterioration following a sustained period of stability or improvement on the ventilator, defined by changes in the daily minimum fraction of inspired oxygen or positive end-expiratory pressure. The second tier definition, infection-related ventilator-associated complication (IVAC), requires that patients with VAC also have an abnormal temperature or white blood cell count, and be started on a new antimicrobial agent. The third tier definitions, possible and probable VAP, require that patients with IVAC also have laboratory and/or microbiological evidence of respiratory infection. Ventilator-associated events surveillance was implemented in January 2013 in the CDC's National Healthcare Safety Network. Modifications to improve surveillance may be made as additional data become available and users gain experience with the new definitions.

Unexpected hemophagocytic syndrome in a post-cardiac surgery patient

In a recent issue of Critical Care, we read with interest the article on the incidence of hemophagocytic lympho-histiocytosis (HLH) in patients with H1N1 infection [1]. Acquired HLH is associated with infections (particularly viral), malignancy, and auto-immune disorders [2]. We describe a case of HLH in a 66-year-old woman admitted to the intensive care unit after aortic valve replacement. She had a history of a cerebral vascular event and diabetes mellitus type 2. After surgery, she had an unexplained increase in oxygen demand and a fever. Standard antibiotics were started for probable ventilator-associated pneumonia and were discontinued after negative cultures. A cardiac evaluation showed good valve patency. Laboratory tests showed elevated creatine kinase (3,562 U/L), lactate dehydrogenase (1,380 U/L), ferritin (3,960 μg/L), and triglyceride (2.29 mmol/L) and decreased hemoglobin (64 g/L), platelets (54 × 109/L), fibrinogen (1.0 g/L), and haptoglobin (<0.2 g/L). Th e results of a Coombs test were negative. Schistocytes were absent. Bone marrow aspiration showed marked hemophagocytosis. An eliciting factor could not be found. Because criteria for HLH were met, we started prednisone treatment. Our patient made a satisfactory recovery. Fever, thrombocytopenia, and anemia are common after cardiac surgery. Without the finding of a markedly elevated ferritin level in our patient, the proper diagnosis could have been missed or her condition could have been misclassified as sepsis with multiple organ failure [3]. To the best of our knowledge, this is the first published case of HLH to occur after cardiac surgery but without a known eliciting cause. This raises a tantalizing thought: unknown triggers may have a role in the pathogenesis of HLH. It would be interesting to search for HLH in a cohort of cardiac surgery patients.

Tracheal Aspirate Correlates With Protected Specimen Brush in Long-term Ventilated Patients Who Have Clinical Pneumonia

This study was undertaken to determine whether tracheal aspirate cultures correlate with protected specimen brush (PSB) cultures in the diagnosis of probable ventilator-associated pneumonia (VAP). Retrospective evaluation of 52 episodes of clinical pneumonia in 38 patients who underwent bronchoscopy and PSB as well as tracheal aspirate cultures. The study took place in long-term, acute care hospital associated with a university medical school. This hospital specializes in ventilator-assisted patients. The patient population consisted of long-term ventilated patients (average ventilation time was 22 weeks; range, 4 weeks to 3 years) who presented with the clinical diagnosis of VAP (fever, increased white blood cell count, new infiltrate on chest radiograph, and bronchorrhea). No patient had received antibiotics for the preceding 5 days at the time of bronchoscopy or tracheal aspirate culture. The tracheal aspirate and PSB culture and sensitivities results. Identical organisms were recovered in both the tracheal aspirate and PSB cultures in 36 of 52 episodes of VAP (69 percent). No organism was recovered in either the tracheal aspirate or the PSB in 4 of 52 suspected episodes (8 percent). Positive bacterial cultures in the tracheal aspirate but not the PSB were found in 8 of 52 (15 percent) episodes. In 3 of 52 episodes (6 percent), 1 isolate of pathogenic bacteria was found on PSB and 2 were found on tracheal aspirate cultures. However, all three isolates had the similar antibiotic sensitivities. In the final episode, the PSB culture grew an organism that was not present in the tracheal aspirate culture (2 percent). When comparing the tracheal aspirate with the PSB, the following were calculated: sensitivity = 97.7 percent; specificity = 50 percent; positive predictive value = 91.3 percent; and negative predictive value = 80 percent. Tracheal aspirate cultures correlate with PSB cultures in patients receiving long-term ventilation who have clinical pneumonia, and they can be used to direct initial antibiotic therapy in this group of patients.