Clinical Significance of Upper Airway Virus Detection in Critically Ill Hematology Patients

Association Between Type of Immunosuppression and the Incidence, Microbiology, and Outcomes of Bacterial Ventilator-Associated Lower Respiratory Tract Infections: A Retrospective Multicenter Study

OBJECTIVES

Ventilator-associated lower respiratory tract infections (VALRTIs) are among the most common ICU-acquired infections in patients receiving invasive mechanical ventilation (IMV). Immunocompromised patients may have a lower incidence of VALRTI when compared with nonimmunocompromised patients, but the influence of the type of immunosuppression on the epidemiology of VALRTI has not been investigated. The study objectives were to assess the association of the type of immunosuppression with the incidence, microbiology, and outcomes (ICU mortality, ICU length of stay, and duration of IMV) of VALRTI related to bacterial pathogens.

DESIGN

Multicenter, international retrospective cohort study.

SETTING

One hundred eighteen ICUs (118) in nine countries.

PATIENTS

Eight hundred fifty-four immunocompromised adult patients (median age, 65 yr; 57.6% males) requiring IMV for greater than 48 hours, including 162 with hematologic malignancies.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients with hematologic malignancies had a lower 28-day cumulative incidence of bacterial VALRTI than patients with other types of immunosuppression (13.6% vs. 20.1%; adjusted cause-specific hazard ratio, 0.61; 95% CI, 0.37-0.97), mostly due to a lower incidence of ventilator-associated pneumonia (9.3% vs. 13.9%). The proportion of VALRTI cases related to multidrug-resistant bacteria was similar between groups. Occurrence of bacterial VALRTI was associated with an increased mortality and a longer ICU length of stay, but this effect was independent of the type of immunosuppression.

CONCLUSIONS

Patients with hematologic malignancies had a lower 28-day cumulative incidence of bacterial VALRTI than patients with other types of immunosuppression, mainly due to a lower incidence of ventilator-associated pneumonia.

Emergency medicine updates: Management of sepsis and septic shock

INTRODUCTION

Sepsis is a common condition associated with significant morbidity and mortality. Emergency physicians play a key role in the diagnosis and management of this condition.

OBJECTIVE

This paper evaluates key evidence-based updates concerning the management of sepsis and septic shock for the emergency clinician.

DISCUSSION

Sepsis is a life-threatening syndrome, and rapid diagnosis and management are essential. Antimicrobials should be administered as soon as possible, as delays are associated with increased mortality. Resuscitation targets include mean arterial pressure ≥ 65 mmHg, mental status, capillary refill time, lactate, and urine output. Intravenous fluid resuscitation plays an integral role in those who are fluid responsive. Balanced crystalloids and normal saline are both reasonable options for resuscitation. Early vasopressors should be initiated in those who are not fluid-responsive. Norepinephrine is the recommended first-line vasopressor, and if hypotension persists, vasopressin should be considered, followed by epinephrine. Administration of vasopressors through a peripheral 20-gauge or larger intravenous line is safe and effective. Steroids such as hydrocortisone and fludrocortisone should be considered in those with refractory septic shock.

CONCLUSION

An understanding of the recent updates in the literature concerning sepsis and septic shock can assist emergency clinicians and improve the care of these patients.

Diagnostic value of metagenomic next-generation sequencing combined by medical thoracoscopy surgery among infectious pleural effusion patients

BACKGROUND

Metagenomic next-generation sequencing (mNGS) is a novel method for identifying pathogens in infectious diseases. This study aimed to explored the application value of mNGS in diagnosing pulmonary infections with pleural effusion, confirmed by medical thoracoscopy.

METHODS

We retrospectively reviewed 25 patients with pulmonary infections and pleural effusion between July 2020 and December 2021. All patients had their diagnosis confirmed by medical thoracoscopy to obtain tissue samples for both traditional testing and mNGS. Samples included pleural effusion, successive sputum, and tissue obtained through medical thoracoscopy. We wanted to assess how effective mNGS was in accurately diagnosing these infections.

RESULTS

This study found that the positive predictive value of mNGS (76% (19/25)) was significantly higher than that of traditional testing (32% (8/25)). The most commonly identified pathogens were Mycobacterium tuberculosis (n = 5), followed by Fusobacterium nucleatum (n = 4), Torque teno virus (n = 4), Streptococcus intermedius (n = 3), Peptostreptococcus stomatis (n = 2), Porphyromonas endodontalis (n = 2), and Campylobacter rectus (n = 2). The percentage of mNGS-positive cases was significantly higher than that from traditional testing for bacteria, but the superiority of mNGS for tuberculosis detection was insignificant. Ten cases were identified with mixed infections by mNGS, while no mixed infections were found by traditional testing.

CONCLUSIONS

Our study showed that using mNGS in combination with biopsy samples obtained through medical thoracoscopy resulted in higher positive rates compared to traditional tests and provided more evidence of pathogens for patients with infectious pleural effusion.

Coronavirus Disease 2019 and Emerging Lung Infections in the Immunocompromised Patient

The immunocompromised are at higher risk of COVID-19 and lung infections, and these are associated with more severe presentations and greater risk of complication, increasing the risks of intensive care unit admission and poor outcomes. However, only limited high-quality data are available about the diagnosis and management of lung infections in this population, with many clinical trials and other large studies excluding the immunocompromised. Well-designed studies are needed to better understand the optimal diagnostic and management options to improve outcomes in the increasingly heterogeneous group of immunocompromised patients.

Utilizing Targeted Next-Generation Sequencing for Rapid, Accurate, and Cost-Effective Pathogen Detection in Lower Respiratory Tract Infections

Objective

To evaluate the diagnostic performance and clinical impact of targeted next-generation sequencing (tNGS) in patients with suspected lower respiratory tract infections.

Methods

Following propensity score matching, we compared the diagnostic performances of tNGS and metagenomic next-generation sequencing (mNGS). Furthermore, the diagnostic performance of tNGS was compared with that of culture, and its clinical impact was assessed.

Results

After propensity score matching, the coincidence rate of tNGS was comparable to that of mNGS (82.9% vs 73.9%, P=0.079). The detection rates for bacterial, viral, fungal, and mixed infections were not significantly different (P>0.05). Bacterial-viral co-infection (16.7%) was the most common mixed infection detected by tNGS. tNGS showed a higher detection rate than culture (75.2% vs 19.0%, P<0.01). The positive detection rate by tNGS was not significantly different between immunocompromised and immunocompetent patients (88.6% vs 80.5%, P=0.202), but was significantly higher than that by culture (P<0.001). Moreover, 65 patients (44.5%) had their medications modified based on the tNGS results, and the majority exhibited notable improvement regardless of treatment adjustment.

Conclusion

tNGS performs comparably to mNGS and surpasses culture in detecting lower respiratory tract infections. Nevertheless, tNGS is faster and more cost-effective than mNGS, making it highly significant for guiding rational treatment.

Acute respiratory failure in adult patients with acute myeloid leukemia

INTRODUCTION

Patients with acute myeloid leukemia (AML) are at high risk of developing life-threatening complications. It is estimated that a quarter of adult patients diagnosed with AML will require admission to the intensive care unit (ICU) at least once during their disease. Acute respiratory failure (ARF) is the main reason for ICU admission and is associated with high mortality rates, depending on the etiology of ARF.

AREAS COVERED

In this population, the high prevalence of severe pulmonary infections highlights the importance of immunosuppression caused by the disease and its treatment. In the early stages of the disease, in addition to pneumonia, which should be systematically sought, leukemia-specific lung involvement (leukostasis, leukemic pulmonary infiltration, and acute lysis pneumopathy) is an important cause of ARF in this population, representing up to 60% of cases. This review aims to help understand the pathophysiology and management of leukemia-specific lung involvement, based on the most contemporary literature.

EXPERT OPINION

The number of AML patients requiring ICU care is expected to increase. AML patients admitted to the ICU for ARF have a high mortality rate, but survivors have encouraging long-term outcomes. Future research will focus on improving risk stratification, cytoreduction, oxygenation strategies, and diagnostic techniques for ARF.

The clinical application of metagenomic next-generation sequencing in immunocompromised patients with severe respiratory infections in the ICU

BACKGROUND

Early targeted antibiotic therapy is crucial for improving the prognosis of immunocompromised patients with severe respiratory infections (SRIs) in the intensive care unit (ICU). Metagenomic next-generation sequencing (mNGS) has shown significant value in pathogen detection, but research on lower respiratory tract microorganisms remains limited.

METHODS

This study enrolled 234 patients with SRIs in the ICU, and individuals were categorized into immunocompromised and immunocompetent groups. We compared the diagnostic performance of mNGS using bronchoalveolar lavage fluid (BALF) with conventional microbiological tests (CMTs) and analyzed the value of mNGS in immunocompromised patients with SRIs in the ICU.

RESULTS

Among all patients, the pathogenic microorganism detection rate of mNGS was higher than that of CMTs (94.02% vs 66.67%, P < 0.05), both in the immunocompromised group (95.0% vs 58.75%, P < 0.05) and the immunocompetent group (93.51% vs 71.43%, P < 0.05). mNGS detected more pathogens than CMTs did (167 vs 51), identifying 116 organisms that were missed by CMTs. The proportion of antibiotic regimen adjustments based on mNGS results was significantly higher compared to CMTs in both the immunocompromised (70.00% vs 17.50%, P < 0.05) and immunocompetent groups (48.70% vs 15.58%, P < 0.05). In the immunocompromised group, patients who had their antibiotic treatment adjusted on mNGS results had improved prognosis, with significantly lower ICU mortality (8.93% vs 50%, P < 0.05) and 28-day mortality rates (30.36% vs 68.75%, P < 0.05) than CMTs. In the immunocompetent group, no statistically significant differences were observed in ICU mortality or 28-day mortality (20.00% vs 33.33%, P > 0.05; 42.67% vs 45.83%, P > 0.05).

CONCLUSION

mNGS shows significant value in detecting pathogens in immunocompromised patients with SRIs in ICU. For immunocompromised patients who respond poorly to empirical treatment, mNGS can provide an etiological basis, helping adjust antibiotic regimens more precisely and thereby improving patient prognosis.

Clinical Impact of Community-Acquired Respiratory Viruses in Patients With Solid Organ Transplants

BACKGROUND

Community-acquired respiratory viruses (CARVs) are associated with poor outcome in solid organ transplant recipients. We reviewed some of these outcomes such as respiratory support, length of stay, admission to the intensive care unit, steroid use, and 30-day all-cause mortality.

METHODS

Multihospital, single center, retrospective review of electronic health records from January 1, 2014, to December 31, 2019.

RESULTS

Twenty-three solid organ transplant recipients (20 male and 3 female) who tested positive for CARVs were identified. The mean age at admission was 60 years, average length of stay was 8 days with 2 patients needing >2 weeks. Six patients required intensive care unit and 8 required supplemental oxygen support. CARV distribution was rhinovirus in 48%, parainfluenza in 29%, metapneumovirus in 12%, respiratory syncytial virus in 0.03%, adenovirus in 0.03%, and non-novel coronavirus in 0.06%. All patients were immunosuppressed, intravenous immunoglobulins were used in 3 patients, antivirals in 7 patients (ribavirin in 6 and oseltamivir in 1), and steroids in 10 patients. Twelve patients had transplant organ biopsy with 5 showing acute cellular rejection. Thirty-five percent of patients died within 1 year (2 during the same admission).

CONCLUSION

Transplant recipients are at a high risk of infections, especially CARVs, which may increase morbidity and mortality. In our observational study, we assessed patients with solid organ transplants who were admitted and tested positive for CARVs, and the associated impact on their clinical course. Careful analysis of the results will help us to emphasize the importance of timely diagnosis and treatment in specific populations.

Severe Community-Acquired Pneumonia in Immunocompromised Patients

Due to higher survival rates with good quality of life, related to new treatments in the fields of oncology, hematology, and transplantation, the number of immunocompromised patients is increasing. But these patients are at high risk of intensive care unit admission because of numerous complications. Acute respiratory failure due to severe community-acquired pneumonia is one of the leading causes of admission. In this setting, the need for invasive mechanical ventilation is up to 60%, associated with a high hospital mortality rate of around 40 to 50%. A wide range of pathogens according to the reason of immunosuppression is associated with severe pneumonia in those patients: documented bacterial pneumonia represents a third of cases, viral and fungal pneumonia both account for up to 15% of cases. For patients with an undetermined etiology despite comprehensive diagnostic workup, the hospital mortality rate is very high. Thus, a standardized diagnosis strategy should be defined to increase the diagnosis rate and prescribe the appropriate treatment. This review focuses on the benefit-to-risk ratio of invasive or noninvasive strategies, in the era of omics, for the management of critically ill immunocompromised patients with severe pneumonia in terms of diagnosis and oxygenation.

Novel and Rapid Diagnostics for Common Infections in the Critically Ill Patient

There are several novel platforms that enhance detection of pathogens that cause common infections in the intensive care unit. These platforms have a sample to answer time of a few hours, are often higher yield than culture, and have the potential to improve antibiotic stewardship.

ICU-acquired infections in immunocompromised patients

Immunocompromised patients account for an increasing proportion of the typical intensive care unit (ICU) case-mix. Because of the increased availability of new drugs for cancer and auto-immune diseases, and improvement in the care of the most severely immunocompromised ICU patients (including those with hematologic malignancies), critically ill immunocompromised patients form a highly heterogeneous patient population. Furthermore, a large number of ICU patients with no apparent immunosuppression also harbor underlying conditions altering their immune response, or develop ICU-acquired immune deficiencies as a result of sepsis, trauma or major surgery. While infections are associated with significant morbidity and mortality in immunocompromised critically ill patients, little specific data are available on the incidence, microbiology, management and outcomes of ICU-acquired infections in this population. As a result, immunocompromised patients are usually excluded from trials and guidelines on the management of ICU-acquired infections. The most common ICU-acquired infections in immunocompromised patients are ventilator-associated lower respiratory tract infections (which include ventilator-associated pneumonia and tracheobronchitis) and bloodstream infections. Recently, several large observational studies have shed light on some of the epidemiological specificities of these infections-as well as on the dynamics of colonization and infection with multidrug-resistant bacteria-in these patients, and these will be discussed in this review. Immunocompromised patients are also at higher risk than non-immunocompromised hosts of fungal and viral infections, and the diagnostic and therapeutic management of these infections will be covered. Finally, we will suggest some important areas of future investigation.

Impact of bronchoalveolar lavage on the management of immunocompromised hosts

BACKGROUND

Respiratory infections are an important cause of morbidity and mortality in immunocompromised individuals. Fiberoptic bronchoscopy with bronchoalveolar lavage (BAL) is an important tool to detect infectious agents in immunocompromised patients with low respiratory tract infections (LRTI).

RESEARCH QUESTION

BAL changes the management of immunocompromised patients with suspected LRTI.

STUDY DESIGN AND METHODS

Immunocompromised patients with a suspicion of LRTI underwent diagnostic BAL. The primary composite outcome consisted of pre-defined modifications in the management of the immunocompromised patients following BAL. We quantified the impact of bronchoscopy up to 30 days after the procedure.

RESULTS

A total of 2666 visits from 1301 patients were included in the study and immunosuppression was classified as haematological (n = 1040; 544 patients), solid organ transplantation (n = 666; 107 patients) and other causes (n = 960; 650 patients). BAL led to a change in management in 52.36% (n = 1396) of all cases. This percentage, as well as the 30-day mortality differed significantly amongst the three groups. Age, C-reactive protein and aetiology of infection determined significantly the risk of 30-day mortality in all patients. In 1.89% (n = 50) of all cases, a combination of 2 respiratory viral agents was identified and 24.23% (n = 646) were diagnosed with a single respiratory viral agent.

INTERPRETATION

BAL leads to changes in management in the majority of immunosuppressed patients. There is a high prevalence of multimicrobial infections and respiratory viral infections in immunocompromised patients with respiratory symptoms. Individual virus infection is associated with diverse risk of a negative outcome.

A Randomized Controlled Trial to Study the Transmission of SARS-CoV-2 and Other Respiratory Viruses During Indoor Clubbing Events (ANRS0066s ITOC Study)

BACKGROUND

In the context of the circulation of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.617.2 (Delta) variant, vaccination re-authorized mass indoor gatherings. The "Indoor Transmission of coronavirus disease 2019 (COVID-19)" (ITOC) trial (ClinicalTrials.gov, NCT05311865) aimed to assess the risk of transmission of SARS-CoV-2 and other respiratory viruses during an indoor clubbing event among participants fully vaccinated against COVID-19.

METHODS

ITOC, a randomized controlled trial in the Paris region (France), enrolled healthy volunteers aged 18-49 years, fully vaccinated against COVID-19, with no comorbidities or symptoms, randomized 1:1 to be interventional group "attendees" or control "non-attendees." The intervention was a 7-hour indoor event in a nightclub at full capacity, with no masking, prior SARS-CoV-2 test result, or social distancing required. The primary outcome measure was the number of reverse transcriptase-polymerase chain reaction (RT-PCR)-determined SARS-CoV-2-positive subjects using self-collected saliva 7 days post-gathering in the per-protocol population. Secondary endpoints focused on 20 other respiratory viruses.

RESULTS

Healthy participants (n = 1216) randomized 2:1 by blocks up to 10 815 attendees and 401 non-attendees, yielding 529 and 287 subjects, respectively, with day-7 saliva samples. One day-7 sample from each group was positive. Looking at all respiratory viruses together, the clubbing event was associated with an increased risk of infection of 1.59 (95% CI, 1.04-2.61).

CONCLUSIONS

In the context of low Delta variant of concern circulation, no evidence of SARS-CoV-2 transmission among asymptomatic and vaccinated participants was found, but the risk of other respiratory virus transmission was higher. Clinical Trials Registration. ClinicalTrials.gov, NCT05311865.

Multiplex Polymerase Chain Reaction Assay to Detect Nasopharyngeal Viruses in Immunocompromised Patients With Acute Respiratory Failure

BACKGROUND

In immunocompromised patients with acute respiratory failure (ARF), the clinical significance of respiratory virus detection in the nasopharynx remains uncertain.

RESEARCH QUESTION

Is viral detection in nasopharyngeal swabs associated with causes and outcomes of ARF in immunocompromised patients?

STUDY DESIGN AND METHODS

This preplanned post hoc analysis of a randomized controlled trial enrolled immunocompromised patients admitted to 32 ICUs for ARF between May 2016 and December 2017. Nasopharyngeal swabs sampled at inclusion were assessed for 23 respiratory pathogens using multiplex polymerase chain reaction (PCR) assay. Causes of ARF were established by managing physicians and were reviewed by three expert investigators masked to the multiplex PCR assay results. Associations between virus detection in nasopharyngeal swabs, causes of ARF, and composite outcome of day 28 mortality, invasive mechanical ventilation (IMV), or both were assessed.

RESULTS

Among the 510 sampled patients, the multiplex PCR assay results were positive in 103 patients (20.2%), and a virus was detected in 102 samples: rhinoviruses or enteroviruses in 35.5%, coronaviruses in 10.9%, and flu-like viruses (influenza virus, parainfluenza virus, respiratory syncytial virus, human metapneumovirus) in 52.7%. The cause of ARF varied significantly according to the results of the multiplex PCR assay, especially the proportion of viral pneumonia: 50.0% with flu-like viruses, 14.0% with other viruses, and 3.6% when no virus was detected (P < .001). No difference was found in the composite outcome of day 28 mortality, IMV, or both according to positive assay findings (54.9% vs 54.7%; P = .965). In a pre-established subgroup analysis, flu-like virus detection was associated with a higher rate of day 28 mortality, IMV, or both among recipients of allogeneic hematopoietic stem cell transplantation compared with those without detected virus.

INTERPRETATION

In immunocompromised patients with ARF, the results of nasopharyngeal multiplex PCR assays are not associated with IMV or mortality. A final diagnosis of viral pneumonia is retained in one-third of patients with positive assay results and in one-half of the patients with a flu-like virus.

Utility of Respiratory Pathogen Panels in the Outpatient Oncology Setting

Oncology patients presenting for outpatient evaluation of a respiratory tract infection (RTI) are often tested for a variety of viruses with a respiratory pathogen panel (RPP) in addition to influenza and SARS-CoV-2. This triad of testing is expensive and uncomfortable because it requires 2 nasal swabs. Little evidence supports the use of an RPP in outpatient settings, but it is routinely ordered. This retrospective chart review analyzed 183 RPPs performed at Jefferson between April 2020 and November 2021 in outpatient oncology patients presenting with RTI. Data collected included patient demographics, symptoms, and exam findings at time of RPP, additional testing completed, results of RPP, antibiotic and antiviral use before and after RPP results, and patient outcomes 30 days after RPP. Descriptive statistics were calculated. Of the 183 RPPs analyzed, 16.9% (31) were positive for at least 1 respiratory virus. Fifty-two patients (28.4%) started antibiotics before results of the RPP. Of those, 2 patients (3.8%) had a change in antibiotic plan after RPP results returned. Zero patients were started on antiviral medication before results of the RPP. One patient started antiviral treatment after RPP results returned. In total, only 3 patients (1.6%) had an RPP-driven change in medication management. This study suggests limited utility in use of RPPs for oncology patients presenting to the office with RTI symptoms. Targeted testing with a single nasal swab for influenza, RSV, and SARS-CoV-2 may be more clinically relevant. The authors hope to use these data to implement a quality improvement initiative to reduce RPP utilization in this population.

Society of Critical Care Medicine and the Infectious Diseases Society of America Guidelines for Evaluating New Fever in Adult Patients in the ICU

RATIONALE

Fever is frequently an early indicator of infection and often requires rigorous diagnostic evaluation.

OBJECTIVES

This is an update of the 2008 Infectious Diseases Society of America and Society (IDSA) and Society of Critical Care Medicine (SCCM) guideline for the evaluation of new-onset fever in adult ICU patients without severe immunocompromise, now using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology.

PANEL DESIGN

The SCCM and IDSA convened a taskforce to update the 2008 version of the guideline for the evaluation of new fever in critically ill adult patients, which included expert clinicians as well as methodologists from the Guidelines in Intensive Care, Development and Evaluation Group. The guidelines committee consisted of 12 experts in critical care, infectious diseases, clinical microbiology, organ transplantation, public health, clinical research, and health policy and administration. All task force members followed all conflict-of-interest procedures as documented in the American College of Critical Care Medicine/SCCM Standard Operating Procedures Manual and the IDSA. There was no industry input or funding to produce this guideline.

METHODS

We conducted a systematic review for each population, intervention, comparison, and outcomes question to identify the best available evidence, statistically summarized the evidence, and then assessed the quality of evidence using the GRADE approach. We used the evidence-to-decision framework to formulate recommendations as strong or weak or as best-practice statements.

RESULTS

The panel issued 12 recommendations and 9 best practice statements. The panel recommended using central temperature monitoring methods, including thermistors for pulmonary artery catheters, bladder catheters, or esophageal balloon thermistors when these devices are in place or accurate temperature measurements are critical for diagnosis and management. For patients without these devices in place, oral or rectal temperatures over other temperature measurement methods that are less reliable such as axillary or tympanic membrane temperatures, noninvasive temporal artery thermometers, or chemical dot thermometers were recommended. Imaging studies including ultrasonography were recommended in addition to microbiological evaluation using rapid diagnostic testing strategies. Biomarkers were recommended to assist in guiding the discontinuation of antimicrobial therapy. All recommendations issued were weak based on the quality of data.

CONCLUSIONS

The guidelines panel was able to formulate several recommendations for the evaluation of new fever in a critically ill adult patient, acknowledging that most recommendations were based on weak evidence. This highlights the need for the rapid advancement of research in all aspects of this issue-including better noninvasive methods to measure core body temperature, the use of diagnostic imaging, advances in microbiology including molecular testing, and the use of biomarkers.

Prognosis of critically ill immunocompromised patients with virus-detected acute respiratory failure

BACKGROUND

Acute respiratory failure (ARF) is the leading cause of ICU admission. Viruses are increasingly recognized as a cause of pneumonia in immunocompromised patients, but epidemiologic data are scarce. We used the Groupe de Recherche en Réanimation Respiratoire en Onco-Hématologie's database (2003-2017, 72 intensive care units) to describe the spectrum of critically ill immunocompromised patients with virus-detected ARF and to report their outcomes. Then, patients with virus-detected ARF were matched based on clinical characteristics and severity (1:3 ratio) with patients with ARF from other origins.

RESULTS

Of the 4038 immunocompromised patients in the whole cohort, 370 (9.2%) had a diagnosis of virus-detected ARF and were included in the study. Influenza was the most common virus (59%), followed by respiratory syncytial virus (14%), with significant seasonal variation. An associated bacterial infection was identified in 79 patients (21%) and an invasive pulmonary aspergillosis in 23 patients (6%). The crude in-hospital mortality rate was 37.8%. Factors associated with mortality were: neutropenia (OR = 1.74, 95% confidence interval, CI [1.05-2.89]), poor performance status (OR = 1.84, CI [1.12-3.03]), and the need for invasive mechanical ventilation on the day of admission (OR = 1.97, CI [1.14-3.40]). The type of virus was not associated with mortality. After matching, patients with virus-detected ARF had lower mortality (OR = 0.77, CI [0.60-0.98]) than patients with ARF from other causes. This result was mostly driven by influenza-like viruses, namely, respiratory syncytial virus, parainfluenza virus, and human metapneumovirus (OR = 0.54, CI [0.33-0.88]).

CONCLUSIONS

In immunocompromised patients with virus-detected ARF, mortality is high, whatever the species, mainly influenced by clinical severity and poor general status. However, compared to non-viral ARF, in-hospital mortality was lower, especially for patients with detected viruses other than influenza.

Sepsis and acute respiratory failure in patients with cancer: how can we improve care and outcomes even further?

PURPOSE OF REVIEW

Care and outcomes of critically ill patients with cancer have improved over the past decade. This selective review will discuss recent updates in sepsis and acute respiratory failure among patients with cancer, with particular focus on important opportunities to improve outcomes further through attention to phenotyping, predictive analytics, and improved outcome measures.

RECENT FINDINGS

The prevalence of cancer diagnoses in intensive care units (ICUs) is nontrivial and increasing. Sepsis and acute respiratory failure remain the most common critical illness syndromes affecting these patients, although other complications are also frequent. Recent research in oncologic sepsis has described outcome variation - including ICU, hospital, and 28-day mortality - across different types of cancer (e.g., solid vs. hematologic malignancies) and different sepsis definitions (e.g., Sepsis-3 vs. prior definitions). Research in acute respiratory failure in oncology patients has highlighted continued uncertainty in the value of diagnostic bronchoscopy for some patients and in the optimal respiratory support strategy. For both of these syndromes, specific challenges include multifactorial heterogeneity (e.g. in etiology and/or underlying cancer), delayed recognition of clinical deterioration, and complex outcomes measurement.

SUMMARY

Improving outcomes in oncologic critical care requires attention to the heterogeneity of cancer diagnoses, timely recognition and management of critical illness, and defining appropriate ICU outcomes.

[Invasive mechanical ventilation in patients with solid tumor or hematological malignancy]

Invasive mechanical ventilation in onco-hematology patients has become relatively routine, and is now part and parcel of their care pathway. Nevertheless, specific complications and subsequent therapeutic possibilities require discussion. To a greater extent than with regard to other patient populations, cooperation between specialist and ICU physician is mandatory, the objective being to more comprehensively assess a therapeutic project before or during the period of invasive mechanical ventilation. After an overview of recent results concerning ventilated patients in intensive care, this review aims to describe the specific complications and factors associated with mortality in this population.

Clinical significance of human metapneumovirus detection in critically ill adults with lower respiratory tract infections

BACKGROUND

Unlike other viruses, the pathogenicity of human metapneumovirus (hMPV) in adults remains uncertain. To address this question, a retrospective monocentric cohort including all patients admitted to ICU with hMPV infection between January 1, 2010, and June 30, 2018 was performed. The characteristics of hMPV infected patients were studied and compared to matched influenza infected patients. Consecutively, a systematic review and meta-analyses investigating PUBMED, EMBASE and COCHRANE databases was conducted to explore the hMPV infections in adult patients (PROSPERO number: CRD42018106617). Trials, case series, and cohorts published between January 1, 2008 and August 31, 2019 compiling adults presenting hMPV infections were included. Pediatric studies were excluded. Data were extracted from published reports. Primary endpoint was the rate of low respiratory tract infections (LRTIs) among all hMPV infected patients.

RESULTS

During the study period, 402 patients were tested positive for hMPV. Among them 26 (6.5%) patients were admitted to the ICU, 19 (4.7%) for acute respiratory failure. Twenty-four (92%) were immunocompromised. Bacterial coinfections were frequent 53.8%. Hospital mortality rate was 30.8%. In the case-control analysis, the clinical and imaging characteristics were not different between hMPV and influenza infected patients. The systematic review identified 156 studies and 69 of them (1849 patients) were eligible for analysis. Although there was heterogeneity between the studies, the rate of hMPV LRTIs was 45% (95% CI 31-60%; I² = 98%). Intensive care unit (ICU) admission was required for 33% (95% CI 21-45%; I² = 99%). Hospital mortality rate was 10% (95% CI 7-13%; I² = 83%) and ICU mortality rate was 23% (95% CI 12-34%; I² = 65%). Underlying malignancy was independently associated with increased mortality rate.

CONCLUSIONS

This preliminary work suggested that hMPV may be associated with severe infection and high mortality in patients with underlying malignancies. However, regarding the small size of the cohort and the heterogeneity of the review, more cohort studies are warranted.

Ventilator-Associated Pneumonia in Immunosuppressed Patients

Immunocompromised patients-including patients with cancer, hematological malignancies, solid organ transplants and individuals receiving immunosuppressive therapies for autoimmune diseases-account for an increasing proportion of critically-ill patients. While their prognosis has improved markedly in the last decades, they remain at increased risk of healthcare- and intensive care unit (ICU)-acquired infections. The most frequent of these are ventilator-associated lower respiratory tract infections (VA-LTRI), which include ventilator-associated pneumonia (VAP) and tracheobronchitis (VAT). Recent studies have shed light on some of the specific features of VAP and VAT in immunocompromised patients, which is the subject of this narrative review. Contrary to previous belief, the incidence of VAP and VAT might actually be lower in immunocompromised than non-immunocompromised patients. Further, the relationship between immunosuppression and the incidence of VAP and VAT related to multidrug-resistant (MDR) bacteria has also been challenged recently. Etiological diagnosis is essential to select the most appropriate treatment, and the role of invasive sampling, specifically bronchoscopy with bronchoalveolar lavage, as well as new molecular syndromic diagnostic tools will be discussed. While bacteria-especially gram negative bacteria-are the most commonly isolated pathogens in VAP and VAT, several opportunistic pathogens are a special concern among immunocompromised patients, and must be included in the diagnostic workup. Finally, the impact of immunosuppression on VAP and VAT outcomes will be examined in view of recent papers using improved statistical methodologies and treatment options-more specifically empirical antibiotic regimens-will be discussed in light of recent findings on the epidemiology of MDR bacteria in this population.

Association between early corticosteroid administration and long-term survival in non-infectious pulmonary complications after allogeneic hematopoietic stem cell transplantation

Non-infectious pulmonary complications (NIPCs) after allogeneic hematopoietic stem cell transplantation (HSCT) are associated with poor outcomes. It is important to maximize the effectiveness of primary treatment because secondary treatment has not been established. We analyzed data from 393 patients who underwent allogeneic HSCT during a 10-year period. Thirty-seven were diagnosed with NIPCs, which consisted of idiopathic pneumonia syndrome, bronchiolitis obliterans, and interstitial lung disease including cryptogenic organizing pneumonia. Among these, 18 died (Dead group) while 19 remained alive (Alive group) during the study period. The median time between NIPC diagnosis and first administration of ≥ 1 mg/kg/day corticosteroids (prednisolone dose equivalent) was significantly longer in the Dead group than the Alive group, at 9 days versus 4 days (p = 0.01). We further divided these cases into those who received prednisolone within seven days and after 8 days. We found that the ≤ 7 days group were more likely to survive after their NIPC diagnosis compared to the ≥ 8 days group (p = 0.06). Our analysis showed that early initiation of corticosteroid therapy is associated with long-term survival in NIPCs.

Novel and Rapid Diagnostics for Common Infections in the Critically Ill Patient

There are several novel platforms that enhance detection of pathogens that cause common infections in the intensive care unit. These platforms have a sample to answer time of a few hours, are often higher yield than culture, and have the potential to improve antibiotic stewardship.

Ventilator-associated pneumonia prevention in the Intensive care unit using Postpyloric tube feeding in China (VIP study): study protocol for a randomized controlled trial

BACKGROUND

Ventilator-associated pneumonia is a challenge in critical care and is associated with high mortality and morbidity. Although some consensuses on preventing ventilator-associated pneumonia are reached, it is still somewhat controversial. Meta-analysis has shown that postpyloric tube feeding may reduce the incidences of ventilator-associated pneumonia, which still desires high-quality evidence. This trial aims to evaluate the efficacy and safety profiles of postpyloric tube feeding versus gastric tube feeding.

METHODS/DESIGN

In this multicenter, open-label, randomized controlled trial, we will recruit 924 subjects expected to receive mechanical ventilation for no less than 48 h. Subjects on mechanical ventilation will be randomized (1:1) to receive postpyloric or gastric tube feeding and routine preventive measures simultaneously. The primary outcome is the proportion of patients with at least one ventilator-associated pneumonia episode. Adverse events and serious adverse events will be observed closely.

DISCUSSION

The VIP study is a large-sample-sized, multicenter, open-label, randomized, parallel-group, controlled trial of postpyloric tube feeding in China and is well-designed based on previous studies. The results of this trial may help to provide evidence-based recommendations for the prevention of ventilator-associated pneumonia.

TRIAL REGISTRATION

Chictr.org.cn ChiCTR2100051593 . Registered on 28 September 2021.

Epidemiologic Characteristics and Clinical Significance of Respiratory Viral Infections Among Adult Patients Admitted to the Intensive Care Unit

Background

The diagnosis of respiratory viral infections (RVIs) in critically ill patients is important for determining treatment options and adhering to infection-control protocols. However, data on the incidence and occurrence patterns of RVIs are scarce. We investigated the epidemiology and clinical impact of RVIs in critically ill patients.

Methods

This retrospective observational study was conducted in a tertiary hospital in South Korea between November 2014 and September 2020. Adult patients (≥ 18 years of age) who tested positive for an RVI by multiplex polymerase chain reaction (mPCR) and were admitted to the intensive care unit (ICU) were included in the study. Clinical characteristics and outcomes were obtained by reviewing electronic medical records. Pearson's χ2 test and Fisher's exact test, Mann-Whitney U test was used to compare between groups of patients. Trend analysis and the χ2-based Q test was used to analyze test behavior of physicians performing mPCR test.

Results

Among 22,517 patients admitted to the ICU during the study period, 2,222 (9.9%) underwent mPCR testing for an RVI. The median timing of mPCR testing after ICU admission was 1 day (IQR, 0-2). A total of 335 (15.1%) non-duplicative RVI-positive cases were included in the analysis. The incidence rate of RVIs in ICU patients was 30.45 per 10,000 patient-days. The most frequently detected RVI was influenza A (27.8%), followed by rhinovirus (25.4%). Thirty-two (9.6%) RVI-positive patients were diagnosed with upper respiratory infections, 193 (64.1%) with community-acquired, and 108 (35.9%) with hospital-acquired pneumonia. All-cause mortality and mortality related to respiratory tract infection (RTI) were 30.7% and 22.1%, respectively. The initial presentation of septic shock, requirement for mechanical ventilation, and lymphocytopenia were significant predictors of RTI-related mortality. Of the RVI-positive patients, 151 (45.1%) had nonviral coinfections and presented with higher clinical severity and longer hospital stays than patients infected solely with viral pathogens.

Conclusion

The incidence of RVIs in ICU patients is common. ICU patients with RVIs had high mortality and frequently presented with coinfections with nonviral pathogens, which were associated with a higher clinical severity than sole RVI. Increased testing for RVIs will enhance infection-control efforts and improve patient care.

New Insights into the Prevention of Hospital-Acquired Pneumonia/Ventilator-Associated Pneumonia Caused by Viruses

A fifth or more of hospital-acquired pneumonias may be attributable to respiratory viruses. The SARS-CoV-2 pandemic has clearly demonstrated the potential morbidity and mortality of respiratory viruses and the constant threat of nosocomial transmission and hospital-based clusters. Data from before the pandemic suggest the same can be true of influenza, respiratory syncytial virus, and other respiratory viruses. The pandemic has also helped clarify the primary mechanisms and risk factors for viral transmission. Respiratory viruses are primarily transmitted by respiratory aerosols that are routinely emitted when people exhale, talk, and cough. Labored breathing and coughing increase aerosol generation to a much greater extent than intubation, extubation, positive pressure ventilation, and other so-called aerosol-generating procedures. Transmission risk is proportional to the amount of viral exposure. Most transmissions take place over short distances because respiratory emissions are densest immediately adjacent to the source but then rapidly dilute and diffuse with distance leading to less viral exposure. The primary risk factors for transmission then are high viral loads, proximity, sustained exposure, and poor ventilation as these all increase net viral exposure. Poor ventilation increases the risk of long-distance transmission by allowing aerosol-borne viruses to accumulate over time leading to higher levels of exposure throughout an enclosed space. Surgical and procedural masks reduce viral exposure but do not eradicate it and thus lower but do not eliminate transmission risk. Most hospital-based clusters have been attributed to delayed diagnoses, transmission between roommates, and staff-to-patient infections. Strategies to prevent nosocomial respiratory viral infections include testing all patients upon admission, preventing healthcare providers from working while sick, assuring adequate ventilation, universal masking, and vaccinating both patients and healthcare workers.

Prevalence and clinical course of upper airway respiratory virus infection in critically ill patients with hematologic malignancies

Background

The clinical significance of upper airway respiratory virus (RV) detection in patients with hematologic malignancies remains unclear. We aimed to investigate the association between upper airway RV detection and prognosis in critically ill patients with hematologic malignancies.

Methods

This retrospective observational study included 331 critically ill patients with hematologic malignancies who presented respiratory symptoms and their nasopharyngeal swab was tested using a multiplex PCR assay between January 2017 and December 2018. A logistic regression model was used to adjust for potential confounding factors in the association between assay positivity and in-hospital mortality.

Results

Among the 331 analyzed patients, RVs were detected in 29.0%. The overall mortality rates in the intensive care unit and hospital were 56.8% and 65.9%, respectively. Positive upper airway RV detection was associated with relapsed hematologic malignancies, higher level of C-reactive protein, and prior use of high dose steroids and anti-cancer chemotherapeutic drugs. Furthermore, it was independently associated with in-hospital mortality (adjusted odds ratio, 2.36; 95% confidence interval, 1.23 to 4.54). Among different RVs, parainfluenza virus was more prevalent among patients who died in the hospital than among those who survived (11.5% vs. 3.5%, P = 0.027).

Conclusions

RV detection in the upper respiratory tract was relatively common in our cohort and was significantly associated with a poor prognosis. Thus, it can be used as a predictor of prognosis. Moreover, RV presence in the upper respiratory tract should be examined in patients who have previously been prescribed with high dose corticosteroids and anti-cancer drugs.

Herpesviridae in critically ill hematology patients: HHV-6 is associated with worse clinical outcome

PURPOSE

Although viral infections are frequent among patients with hematological malignancies (HM), data about herpesviridae in critically ill hematology patients are scarce. We aimed at determining the impact of herpesviridae reactivation/infection in this population.

MATERIAL AND METHODS

We performed a single center retrospective study including all consecutive adult hematology patients admitted to our comprehensive cancer center ICU on a 6-year period. Clinical characteristics, microbiological findings, especially virus detection and outcome were recorded.

RESULTS

Among the 364 included patients, HHV-6 was the predominant retrieved herpesviridae (66 patients, 17.9%), followed by HSV1/2 (41 patients, 11.3%), CMV (38 patients, 10.4%), EBV (24 patients, 6.6%) and VZV (3 patients). By multivariable analysis, HHV-6 reactivation was independently associated with hospital mortality (OR, 2.35; 95% CI, 1.03-5.34; P = 0.042), whereas antiviral prophylaxis during ICU stay had a protective effect (OR, 0.41; 95% CI, 0.18-0.95; P = 0.037). HHV-6 pneumonitis was independently associated with 1-year mortality (OR, 6.87; 95% CI, 1.09-43.3; P = 0.04).

CONCLUSIONS

Among critically ill hematology patients, HHV-6 reactivation and pneumonitis are independent risk factors for hospital and 1-year mortality, respectively. Impact of prevention and treatment using agents active against HHV-6 should be assessed to define a consensual diagnostic and therapeutic strategy.

Major pulmonary complications following Hematopoietic stem cell transplantation: What the pulmonologist needs to know

Hematopoietic stem cell transplantation (HSCT) is used for treatment of a myriad of both malignant and non-malignant disorders. However, despite many advances over the years which have resulted in improved patient mortality, this subset of patients remains at risk for a variety of post-transplant complications. Pulmonary complications of HSCT are categorized into infectious and non-infectious and occur in up to one-third of patients undergoing HSCT. Infectious etiologies include bacterial, viral and fungal infections, each of which can have significant mortality if not identified and treated early in the course of infection. Advances in the diagnosis and management of infectious complications highlight the importance of non-infectious pulmonary complications related to chemoradiation toxicities, immunosuppressive drugs toxicities, and graft-versus-host disease. This report aims to serve as a guide and clinical update of pulmonary complications following HSCT for the general pulmonologist who may be involved in the care of these patients.

Exploring the Clinical Utility of Metagenomic Next-Generation Sequencing in the Diagnosis of Pulmonary Infection

INTRODUCTION

We aimed to explore the real-world clinical application value and challenges of metagenomic next-generation sequencing (mNGS) for pulmonary infection diagnosis.

METHODS

We retrospectively reviewed the results of mNGS and conventional tests from 140 hospitalized patients with suspected pulmonary infections from January 2019 to December 2020. The sample types included bronchoalveolar lavage fluid, lung tissue by transbronchial lung biopsy, pleural effusion, blood, and bronchial sputum. Apart from the mNGS reports that our patients received, an extra comprehensive and thorough literature search was conducted.

RESULTS

Significant differences were noticed in the positive detection rates of pathogens between mNGS and conventional diagnostic testing (115/140, 82.14% vs 50/140, 35.71%, P < 0.05). The percentage of mNGS-positive patients was significantly higher than that of conventional testing-positive patients with regard to bacterial detection (P < 0.01), but no significant differences were found with regard to fungal detection (P = 0.67). Significant statistical differences were found between mixed infection cases (15, 22.70%) and single infection cases (4, 7.84%) in terms of diabetes (P = 0.03). The most frequent pattern of mixed infection was bacteria and fungi mixed infection (40, 40/89 = 44.94%), followed by bacteria mixed infection (29, 29/89 = 32.58%). The sensitivity of mNGS in pulmonary infection diagnosis was much higher than that of conventional test (89.17% vs 50.00%; P < 0.01), but the specificity was the opposite (75.00% vs 81.82%; P > 0.05).

CONCLUSION

mNGS is a valuable tool for the detection of pulmonary infections, especially mixed pulmonary infections. The most common combinations we found were bacterial-fungal coinfection and bacterial-bacterial coinfection. Still, there are many challenges in the clinical application of mNGS in the diagnosis of pulmonary infections. There is still a lot of work to be done in interpreting the mNGS reports, because both clinical judgment and literature analysis strategy need to be refined.

Role of the inflammatory response in community-acquired pneumonia: clinical implications

INTRODUCTION

Despite adequate antibiotic coverage, community-acquired pneumonia (CAP) remains a leading cause of hospitalization and mortality worldwide. It induces both a local pulmonary and a systemic inflammatory response, particularly significant in severe cases. The intensity of the dysregulated host response varies from patient to patient and has a negative impact on survival and other outcomes.

AREAS COVERED

This comprehensive review summarizes the pathophysiological aspects of the inflammatory response in CAP, briefly discusses the usefulness of biomarkers, and assesses the clinical evidence for modulating the inflammatory pathways. We searched PubMed for the most relevant studies, reviews, and meta-analysis until August 2020.

EXPERT OPINION

Notable efforts have been made to identify biomarkers that can accurately differentiate between viral and bacterial etiology, and indeed, to enhance risk stratification in CAP. However, none has proven ideal and no recommended biomarker-guided algorithms exist. Biomarker signatures from proteomic and metabolomic studies could be more useful for such assessments. To date, most studies have produced contradictory results concerning the role of immunomodulatory agents (e.g. corticosteroids, macrolides, and statins) in CAP. Adequately identifying the population who may benefit most from effective modulation of the inflammatory response remains a challenge.

Critical Care of Hematopoietic Stem Cell Transplant Patients

Life-threatening complications are frequent after hematopoietic stem cell transplant (HSCT), and optimum critical care is essential to ensuring good outcomes. The immunologic consequences of HSCT result in a markedly different host response to critical illness. Infection is the most common cause of critical illness but noninfectious complications are frequent. Respiratory failure or sepsis are the typical presentations but the sequelae of HSCT can affect nearly any organ system. Pattern recognition can facilitate anticipation and early intervention in post-HSCT critical illness. HSCT critical care is a multidisciplinary endeavor. Continued investigation and focus on process improvement will continue to improve outcomes.

Acute respiratory failure in immunocompromised patients: outcome and clinical features according to neutropenia status

Background

The impact of neutropenia in critically ill immunocompromised patients admitted in a context of acute respiratory failure (ARF) remains uncertain. The primary objective was to assess the prognostic impact of neutropenia on outcomes of these patients. Secondary objective was to assess etiology of ARF according to neutropenia.

Methods

We performed a post hoc analysis of a prospective multicenter multinational study from 23 ICUs belonging to the Nine-I network. Between November 2015 and July 2016, all adult immunocompromised patients with ARF admitted to the ICU were included in the study. Adjusted analyses included: (1) a hierarchical model with center as random effect; (2) propensity score (PS) matched cohort; and (3) adjusted analysis in the matched cohort.

Results

Overall, 1481 patients were included in this study of which 165 had neutropenia at ICU admission (11%). ARF etiologies distribution was significantly different between neutropenic and non-neutropenic patients, main etiologies being bacterial pneumonia (48% vs 27% in neutropenic and non-neutropenic patients, respectively). Initial oxygenation strategy was standard supplemental oxygen in 755 patients (51%), high-flow nasal oxygen in 165 (11%), non-invasive ventilation in 202 (14%) and invasive mechanical ventilation in 359 (24%). Before adjustment, hospital mortality was significantly higher in neutropenic patients (54% vs 42%; p = 0.006). After adjustment for confounder and center effect, neutropenia was no longer associated with outcome (OR 1.40, 95% CI 0.93–2.11). Similar results were observed after matching (52% vs 46%, respectively; p = 0.35) and after adjustment in the matched cohort (OR 1.04; 95% CI 0.63–1.72).

Conclusion

Neutropenia at ICU admission is not associated with hospital mortality in this cohort of critically ill immunocompromised patients admitted for ARF. In neutropenic patients, main ARF etiologies are bacterial and fungal infections.

Respiratory virus-associated infections in HIV-infected adults admitted to the intensive care unit for acute respiratory failure: a 6-year bicenter retrospective study (HIV-VIR study)

Introduction

Acute respiratory failure is the main reason for admission to the intensive care unit (ICU) in HIV-infected adults. There is little data about the epidemiology of respiratory viruses in this population.

Methods

HIV-infected adults admitted to two intensive care units over a 6-year period for an acute respiratory failure and explored for respiratory viruses with multiplex polymerase chain reaction (mPCR) were retrospectively selected. Objectives were to describe the prevalence of respiratory viruses, coinfections with non-viral pathogens, and hospital outcome.

Results

A total of 123 episodes were included. An HIV infection was newly diagnosed in 9% of cases and 72% of the population were on antiretroviral therapy. Real-time mPCR tests identified at least one respiratory virus in the respiratory tract of 33 (27%) patients, but with a non-viral copathogen in two-thirds of cases. Rhinovirus was predominant, documented in 15 patients, followed by Influenza and Respiratory Syncytial Viruses (both n = 6). The prevalence of respiratory virus-associated infection did not vary along with the level of the CD4 T-cell deficiency, except for Rhinovirus which was more prevalent in patients with a CD4 lymphocyte count below 200 cells/µL (n = 13 (20%) vs. n = 2 (4%), p < 0.01). In multivariate analysis, respiratory virus-associated infection was not associated with a worse prognosis.

Conclusions

Viruses are frequently identified in the respiratory tract of HIV-infected patients with acute respiratory failure that requires ICU admission, but with a non-viral copathogen in two-thirds of cases. Rhinovirus is the predominant viral specie; its prevalence is highest in patients with a CD4 lymphocyte count below 200 cells/µL.

Noninfectious pulmonary complications of haematopoietic stem cell transplantation

Haematopoietic stem cell transplantation (HSCT) is an established treatment for a variety of malignant and nonmalignant conditions. Pulmonary complications, both infectious and noninfectious, are a major cause of morbidity and mortality in patients who undergo HSCT. Recent advances in prophylaxis and treatment of infectious complications has increased the significance of noninfectious pulmonary conditions. Acute lung injury associated with idiopathic pneumonia syndrome remains a major acute complication with high morbidity and mortality. On the other hand, bronchiolitis obliterans syndrome is the most challenging chronic pulmonary complication facing clinicians who are taking care of allogeneic HSCT recipients. Other noninfectious pulmonary complications following HSCT are less frequent. This review provides a clinical update of the incidence, risk factors, pathogenesis, clinical characteristics and management of the main noninfectious pulmonary complications following HSCT.

Ventilator-associated pneumonia in adults: a narrative review

Ventilator-associated pneumonia (VAP) is one of the most frequent ICU-acquired infections. Reported incidences vary widely from 5 to 40% depending on the setting and diagnostic criteria. VAP is associated with prolonged duration of mechanical ventilation and ICU stay. The estimated attributable mortality of VAP is around 10%, with higher mortality rates in surgical ICU patients and in patients with mid-range severity scores at admission. Microbiological confirmation of infection is strongly encouraged. Which sampling method to use is still a matter of controversy. Emerging microbiological tools will likely modify our routine approach to diagnosing and treating VAP in the next future. Prevention of VAP is based on minimizing the exposure to mechanical ventilation and encouraging early liberation. Bundles that combine multiple prevention strategies may improve outcomes, but large randomized trials are needed to confirm this. Treatment should be limited to 7 days in the vast majority of the cases. Patients should be reassessed daily to confirm ongoing suspicion of disease, antibiotics should be narrowed as soon as antibiotic susceptibility results are available, and clinicians should consider stopping antibiotics if cultures are negative.

Diagnosis of severe respiratory infections in immunocompromised patients

An increasing number of critically ill patients are immunocompromised. Acute hypoxemic respiratory failure (ARF), chiefly due to pulmonary infection, is the leading reason for ICU admission. Identifying the cause of ARF increases the chances of survival, but may be extremely challenging, as the underlying disease, treatments, and infection combine to create complex clinical pictures. In addition, there may be more than one infectious agent, and the pulmonary manifestations may be related to both infectious and non-infectious insults. Clinically or microbiologically documented bacterial pneumonia accounts for one-third of cases of ARF in immunocompromised patients. Early antibiotic therapy is recommended but decreases the chances of identifying the causative organism(s) to about 50%. Viruses are the second most common cause of severe respiratory infections. Positive tests for a virus in respiratory samples do not necessarily indicate a role for the virus in the current acute illness. Invasive fungal infections (Aspergillus, Mucorales, and Pneumocystis jirovecii) account for about 15% of severe respiratory infections, whereas parasites rarely cause severe acute infections in immunocompromised patients. This review focuses on the diagnosis of severe respiratory infections in immunocompromised patients. Special attention is given to newly validated diagnostic tests designed to be used on non-invasive samples or bronchoalveolar lavage fluid and capable of increasing the likelihood of an early etiological diagnosis.

Vaccination of the Stem Cell Transplant Recipient and the Hematologic Malignancy Patient

Patients with hematologic malignancy or those who undergo hematopoietic stem cell transplantation experience variable degrees of immunosuppression, dependent on underlying disease, therapy received, time since transplant, and complications, such as graft-versus-host disease. Vaccination is an important strategy to mitigate onset and severity of certain vaccine-preventable illnesses, such as influenza, pneumococcal disease, or varicella zoster infection, among others. This article highlights vaccines that should and should not be used in this patient population and includes general guidelines for timing of vaccination administration and special considerations in the context of newer therapies, recent vaccine developments, travel, and considerations for household contacts.

Community-Acquired Respiratory Viruses in Transplant Patients: Diversity, Impact, Unmet Clinical Needs

Patients undergoing solid-organ transplantation (SOT) or allogeneic hematopoietic cell transplantation (HCT) are at increased risk for infectious complications. Community-acquired respiratory viruses (CARVs) pose a particular challenge due to the frequent exposure pre-, peri-, and posttransplantation. Although influenza A and B viruses have a top priority regarding prevention and treatment, recent molecular diagnostic tests detecting an array of other CARVs in real time have dramatically expanded our knowledge about the epidemiology, diversity, and impact of CARV infections in the general population and in allogeneic HCT and SOT patients. These data have demonstrated that non-influenza CARVs independently contribute to morbidity and mortality of transplant patients. However, effective vaccination and antiviral treatment is only emerging for non-influenza CARVs, placing emphasis on infection control and supportive measures. Here, we review the current knowledge about CARVs in SOT and allogeneic HCT patients to better define the magnitude of this unmet clinical need and to discuss some of the lessons learned from human influenza virus, respiratory syncytial virus, parainfluenzavirus, rhinovirus, coronavirus, adenovirus, and bocavirus regarding diagnosis, prevention, and treatment.

Respiratory syncytial virus in hematopoietic cell transplant recipients and patients with hematologic malignancies

In the USA and other western nations, respiratory syncytial virus is one of the most commonly encountered respiratory viruses among patients who have been diagnosed with a hematologic malignancy or who have undergone a stem cell transplant. Multiple studies have been performed to evaluate the complications associated with respiratory syncytial virus infections. Other studies have evaluated therapeutic agents and strategies in which these agents can be used. There have also been numerous reports of outbreaks in bone marrow transplant units and oncology wards, where infection control measures have been invaluable in controlling the spread of disease. However, despite these novel approaches, respiratory syncytial virus continues to be potentially fatal in immunocompromised populations. In this review, we discuss the incidence of respiratory syncytial viral infections, risk factors associated with progression from upper respiratory tract infection to lower respiratory tract infection, other complications and outcomes (including mortality), management strategies, and prevention strategies in patients with a hematologic malignancy and in hematopoietic cell transplant recipients.