The Puzzles of Ventilator-Associated Pneumonia and COVID-19: Absolute Knowns and Relative Unknowns*

Abstract

T he development of ventilator-associated pneumonia (VAP) (1) in ICU patients with severe COVID-19 is common and associated with higher VAP rates compared with non-COVID-19 patients in several retrospective studies (2-6). Additionally, there is an increased risk of shock and blood stream infections associated with VAP in .A challenge in understanding the reason for this increased rate is the lack of a clear definition of VAP in COVID-19. Due to the frequent concomitant presence of fever, leukocytosis, and lung infiltrates due to the viral infection, differentiating bacterial colonization from a new bacterial secondary infection is challenging in the presence of these symptoms and imaging findings of an acute viral pneumonia. In part due to these challenges, the term ventilator-associated lower respiratory tract infection (VA-LRTI) has been used: the rate of VA-LRTI has also been found to be higher in ICU patients with COVID-19 compared with ICU patients with influenza and those without viral infection (7).A key remaining question is why VAP and VA-LRTI occur at higher rates in COVID-19 patients. Proposed reasons for increased rate of VAP and VA-LRTI in COVID-19 include viral immunomodulation, prolonged mechanical ventilation and hospital stay, steroids use, acute respiratory distress syndrome (ARDS), prone positioning, sedating and neuromuscular blocking agents, vasopressor use, extracorporeal mechanical oxygenation utilization, and increased demands of the healthcare system including patient volume, healthcare worker shortages, and use of personal protective equipment (8). Prior studies have not systematically evaluated how VA-LRTI has changed throughout the pandemic.In this issue of Critical Care Medicine, Hedberg et al ( 9) expand on the epidemiology of VA-LRTIs in COVID-19 using a retrospective analysis of ventilated adults in a large Swedish ICU from January 2011 to December 2020. Their primary goal was to evaluate changes in rate of VA-LRTI in COVID-19 compared with non-COVID-19 patients over time. Specifically, they compared COVID-19 patients with non-COVID-19 patients (including influenza and the 10 most common International Classification of Diseases, 10th Edition ICU diagnoses during and prior to the pandemic) and then performed a second analysis comparing the first wave of the COVID-19 pandemic (March-July 2020) with the second wave (October-December 2020).The cohort included 479 COVID-19 ICU episodes and 19,744 non-COVID-19 ICU episodes. Patients with COVID-19 were younger and had

Pulmonary superinfection diagnosed with bronchoalveolar lavage at intubation in COVID patients: A Swedish single‐centre study

“…Furthermore, the relatively high incidence of VAP could depend on numerous other factors such as the immunological effects of SARS‐CoV‐2, mucus formation, prone position, over‐crowded ICUs, lack of equipment, and understaffed ICUs. This has been described in other studies 11,34 …”

“…This has been described in other studies. 11,34 Several of the species observed in BAL at intubation were also commonly observed in VAP BAL. Surprisingly, we observed only one patient with an indistinguishable strain in the initial superinfection and later VAP development.…”

“…T A B L E 1 Baseline characteristics in all COVID-19 patients with or without pulmonary superinfection diagnosed with bronchoalveolar lavage performed within 24 h after intubation. (22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35) .64…”

The Impact of Coronavirus Disease 2019 on Viral, Bacterial, and Fungal Respiratory Infections

“…Ventilator-associated pneumonia (VAP) is defined as a pneumonia developing greater than 48 hours after endotracheal intubation. 119 Diagnosis of HAP or VAP is based on finding a new lung infiltrate plus clinical evidence that the infiltrate is of an infectious origin (new fever, purulent sputum, leukocytosis, and decline in oxygenation).…”

“…HAP/VAP in COVID-19 should be diagnosed in accordance with IDSA/ATS guidelines. 119 , 120 Although a spot test of procalcitonin on admission to the hospital was not found to be helpful for the diagnosis of bacterial CAP coinfection, 116 a procalcitonin trend for patients in the ICU may be more useful. Richards and colleagues 127 found that a 50% increase in procalcitonin levels from its previous value was independently associated with the presence of a secondary bacterial infection (VAP, ventilator-associated tracheobronchitis, or bacteremia) compared with increases in either white blood cell count or C-reactive peptide.…”