Ventilator-associated pneumonia

Last updated
Ventilator-associated pneumonia
Other namesVentilator-acquired pneumonia
Specialty Critical Care Medicine

Pulmonology Paediatric Critical Care Medicine

Infectious Diseases
CausesMechanical ventilation, Microaspiration past endotracheal tube cuff, prior use of broad-spectrum antimicrobials

Ventilator-associated pneumonia (VAP) is a type of lung infection that occurs in people who are on mechanical ventilation breathing machines in hospitals. As such, VAP typically affects critically ill persons that are in an intensive care unit (ICU) and have been on a mechanical ventilator for at least 48 hours. [1] [2] VAP is a major source of increased illness and death. Persons with VAP have increased lengths of ICU hospitalization and have up to a 20–30% death rate. [3] The diagnosis of VAP varies among hospitals and providers but usually requires a new infiltrate on chest x-ray plus two or more other factors. These factors include temperatures of >38 °C or <36 °C, a white blood cell count of >12 × 109/ml, purulent secretions from the airways in the lung, and/or reduction in gas exchange. [2] [4]

Contents

A different less studied infection found in mechanically ventilated people is ventilator-associated tracheobronchitis (VAT). [5] As with VAP, tracheobronchial infection can colonise the trachea and travel to the bronchi. VAT may be a risk factor for VAP. [5]

Signs and symptoms

People who are on mechanical ventilation are often sedated and are rarely able to communicate. As such, many of the typical symptoms of pneumonia will either be absent or unable to be obtained. The most important signs are fever or low body temperature, new purulent sputum, and hypoxemia (decreasing amounts of oxygen in the blood). However, these symptoms may be similar for tracheobronchitis.

Cause

Risk factors

Risk factors for VAP include underlying heart or lung disease, neurologic disease, and trauma, as well as modifiable risk factors such as whether the head of the bed is flat (increased risk) or raised, whether the patient had an aspiration event before intubation, and prior antibiotic exposure. [3] As a result of intubation many of the body's defenses against infections are reduced or impaired; this can result in an ability for microorganisms to enter and cause infection. [6] [1] Patients who are in the ICU for head trauma or other severe neurologic illness, as well as patients who are in the ICU for blunt or penetrating trauma, are at especially high risk of developing VAP. [2] Further, patients hospitalized for blunt trauma are at a higher risk of developing VAP compared to patients with penetrating trauma. [2]

Ventilator-associated tracheobronchitis may be a risk factor for VAP, though not all cases of VAT progress to VAP. [7]

Recent studies have also linked the overall oral health of a patient to the potential development of VAP; suggesting that bacteria found in plaque can "migrate to the respiratory system." [8] [1]

Microbiology

The microbiologic flora responsible for VAP is different from that of the more common community-acquired pneumonia (CAP). In particular, viruses and fungi are uncommon causes in people who do not have underlying immune deficiencies. Though any microorganism that causes CAP can cause VAP, there are several bacteria which are particularly important causes of VAP because of their resistance to commonly used antibiotics. These bacteria are referred to as multidrug resistant (MDR).

The development of molecular diagnostic techniques is changing the understanding of the microbiology of VAP, with an increasing appreciation of the role of hard to culture bacteria and the change in the lung microbiome. [9] A recent finding has highlighted the presence of Mycoplasma in the lavage of patients with VAP, a finding which was largely absent from ventilated patients without VAP and healthy controls. [10] The Mycoplasma species most commonly identified, Mycoplasma salivarium , was able to impair the antibacterial functions of monocytes and macrophages. [10]

Pathophysiology

It is thought by many, that VAP primarily occurs because the endotracheal or tracheostomy tube allows free passage of bacteria into the lower segments of the lung in a person who often has underlying lung or immune problems. Bacteria travel in small droplets both through the endotracheal tube and around the cuff. Often, bacteria colonize the endotracheal or tracheostomy tube and are embolized into the lungs with each breath. Bacteria may also be brought down into the lungs with procedures such as deep suctioning or bronchoscopy. Another possibility is that the bacteria already exist in the mucus lining the bronchial tree, and are just kept in check by the body's first line of defenses. Ciliary action of the cells lining the trachea drive the mucus superiorly, leading to a build-up of fluids around the inflated cuff where there is little to no airway clearance. The bacteria can then colonize easily without disturbance and then rise in numbers enough to become infective. The droplets that are driven into the airstream and into the lung fields are lofted by way of Bernoulli's principle. There is also a condition called oxidative damage that occurs when concentrations of pure oxygen come into prolonged contact with cells and this damages the cilia of the cells, thus inhibiting their action as part of the body's first line of defense.

Whether bacteria also travel from the sinuses or the stomach into the lungs is, as of 2005, controversial. However, spread to the lungs from the blood stream or the gut is uncommon.

Once inside the lungs, bacteria then take advantage of any deficiencies in the immune system (such as due to malnutrition or chemotherapy) and multiply. Patients with VAP demonstrate impaired function of key immune cells, including the neutrophil, both in the blood and in the alveolar space, [11] with this impairment being driven by pro-inflammatory molecules such as C5a. [12] These defects in immune function appear to be causally linked to the development of VAP, as they are seen before clinical infection develops. [13] A combination of bacterial damage and consequences of the immune response lead to disruption of gas exchange with resulting symptoms.

Diagnosis

Diagnosis of ventilator-associated pneumonia is difficult and is not standardized. [14] The criteria used for diagnosis of VAP varies by institution, but tends to be a combination of several of the following radiographic, clinical sign, and laboratory evidence: [15]

  1. Temperature greater than 38 °C or less than 36 °C [15]
  2. White blood cell count greater than 12,000/mm3 or less than 4,000/mm3 [15]
  3. Purulent secretions, increased secretions, or change in secretions [15]
  4. Positive tracheal cultures or bronchoalveolar lavage cultures [15]
  5. Some sign of respiratory distress, such as shortness of breath, rapid breathing, abnormal breathing sounds when listening with stethoscope [15]
  6. Increased need for oxygen on the ventilator [15]
  7. Chest X-rays: at least two serial x-rays showing sustained or worsening shadowing (infiltrates or consolidations) [15]
  8. Positive cultures that were obtained directly from the lung environment, such as from the trachea or bronchioles [15]

As an example, some institutions may require one clinical symptoms such as shortness of breath, one clinical sign such as fever, plus evidence on chest xray and in tracheal cultures. [15]

There is no gold standard for getting cultures to identify the bacteria, virus, or fungus that is causing the pneumonia, and there are invasive and non-invasive strategies for obtaining the culture sample. [16] One non-invasive strategy collects cultures from the trachea of people with symptoms of VAP. Another is more invasive and advocates a bronchoscopy plus bronchoalveolar lavage (BAL) for people with symptoms of VAP. Both strategies also require a new or enlarging infiltrate on chest x-ray as well as clinical signs/symptoms such as fever and shortness of breath. There is no strong evidence to suggest that an invasive method to collect cultures is more effective than a non-invasive method. [16] In addition, a quantitative approach to assessing the culture (performing a bacterial count of the pathogen that is causing the pneumonia) does not appear to be superior to a qualitative approach (determining the presence of the pathogen). [16] In recent years there has been a focus on rapid diagnostics, allowing for detection of significant levels of pathogens before this becomes apparent on microbial cultures. Several approaches have been used, including using host biomarkers such as IL-1β and IL-8. [17] [18] Alternatively, molecular detection of bacteria has been undertaken, with reports that amplifying the pan-bacterial 16S gene can provide a measure of bacterial load. [19] A trial of biomarker-based exclusion of VAP (VAP-RAPID2) demonstrated test effectiveness but did not impact on clinical antibiotic prescribing decisions. [20] Studies of pathogen-focussed molecular diagnostics have shown more promise in improving antimicrobial prescribing, [21] [22] with formal findings from the INHALE randomised controlled trial awaited. Highly sensitive molecular diagnostics have the potential to increase antimicrobial use [23] as they detect dead or colonising bacteria, a combination of host-immune profiling and microbial detection may provide the optimal diagnostic technique. [24]

Blood cultures may reveal the microorganisms causing VAP, but are often not helpful as they are positive in only 25% of clinical VAP cases. [25] Even in cases with positive blood cultures, the bacteremia may be from a source other than the lung infection. [25]

Prevention

Prevention of VAP involves limiting exposure to resistant bacteria, discontinuing mechanical ventilation as soon as possible, and a variety of strategies to limit infection while intubated. Resistant bacteria are spread in much the same ways as any communicable disease. Proper hand washing, sterile technique for invasive procedures, and isolation of individuals with known resistant organisms are all mandatory for effective infection control. A variety of aggressive weaning protocols to limit the amount of time a person spends intubated have been proposed. One important aspect is limiting the amount of sedation that a ventilated person receives.

Weak evidence suggests that raising the head of the bed to at least 30 degrees may help prevent VAP, however further research is required to understand the risks associated with this. [26] Antiseptic mouthwashes (in particular associated with toothbrushing) such as chlorhexidine may also reduce the risk of VAP, [27] although the evidence is mainly restricted to those who have undergone cardiac surgery. [28]

American and Canadian guidelines strongly recommend the use of subglottic secretion drainage (SSD). Special tracheal tubes with an incorporated suction lumen as the EVAC tracheal tube form Covidien / Mallinckrodt can be used for that reason. New cuff technology based on polyurethane material in combination with subglottic drainage (SealGuard Evac tracheal tube from Covidien / Mallinckrodt) showed significant delay in early and late onset of VAP. [29]

There is little evidence that the use of silver-coated endotracheal tubes reduces the incidence of VAP in the first ten days of ventilation. [30] There is tentative evidence that the use of probiotics may reduced the likelihood of getting VAP, however it is unclear if probiotics affect ICU or in-hospital death. [31]

Treatment

Treatment of VAP should be matched to known causative bacteria. However, when VAP is first suspected, the bacteria causing infection is typically not known and broad-spectrum antibiotics are given (empiric therapy) until the particular bacterium and its sensitivities are determined. Empiric antibiotics should take into account both the risk factors a particular individual has for resistant bacteria as well as the local prevalence of resistant microorganisms. If a person has previously had episodes of pneumonia, information may be available about prior causative bacteria. The choice of initial therapy is therefore entirely dependent on knowledge of local flora and will vary from hospital to hospital. Treatment of VAP with a single antibiotic has been reported to result in similar outcomes as with a combination of more than one antibiotics, in terms of cure rates, duration of ICU stay, mortality and adverse effects. [32]

Risk factors for infection with an MDR strain include ventilation for more than five days, recent hospitalization (last 90 days), residence in a nursing home, treatment in a hemodialysis clinic, and prior antibiotic use (last 90 days).

Possible empirical therapy combinations include (but are not limited to):

Therapy is typically changed once the causative bacteria are known and continued until symptoms resolve (often 7 to 14 days). For patients with VAP not caused by nonfermenting Gram-negative bacilli (like Acinetobacter, Pseudomonas aeruginosa) the available evidence seems to support the use of short-course antimicrobial treatments (< or =10 days). [33]

People who do not have risk factors for MDR organisms may be treated differently depending on local knowledge of prevalent bacteria. Appropriate antibiotics may include ceftriaxone, ciprofloxacin, levofloxacin, or ampicillin/sulbactam.

As of 2005, there is ongoing research into inhaled antibiotics as an adjunct to conventional therapy. Tobramycin and polymyxin B are commonly used in certain centres but there is no strong clinical evidence to support their use.

Prognosis

VAP occurring early after intubation typically involves fewer resistant organisms and is thus associated with a more favorable outcome. Because respiratory failure requiring mechanical ventilation is itself associated with a high mortality, determination of the exact contribution of VAP to mortality has been difficult. As of 2006, estimates range from 33% to 50% death in patients who develop VAP. Mortality is more likely when VAP is associated with certain microorganisms (Pseudomonas, Acinetobacter), blood stream infections, and ineffective initial antibiotics. VAP is especially common in people who have acute respiratory distress syndrome (ARDS). [34] [35]

Epidemiology

Between 8 and 28% of patients receiving mechanical ventilation are affected by VAP. [36] VAP can develop at any time during ventilation, but occurs most often in the first week of mechanical ventilation. [3] There is some evidence for gender differences in the course of VAP: men have been found to get VAP more often, but women are more likely to die after contracting VAP. [37] Recent reports indicate that patients with Coronavirus disease 2019 who require mechanical ventilation in an Intensive care unit are at increased risk of ventilator-associated pneumonia, compared to patients without COVID-19 ventilated in the same unit [38] and patients who had viral pneumonitis arising from viruses other than SARS-CoV-2. [39] Why this increased susceptibility should be present remains uncertain, as the noted reports [38] [39] adjusted for duration of ventilation, it is likely that the increased susceptibility relates impaired innate immunity in the lungs. [40] However several observational studies have identified the use of glucocorticoids as a factor associated with increased risk of VAP [41] [42] and other Hospital-acquired infections. [43]

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<span class="mw-page-title-main">Pneumonia</span> Inflammation of the alveoli of the lungs

Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severity of the condition is variable.

<span class="mw-page-title-main">Sepsis</span> Life-threatening organ dysfunction triggered by infection

Sepsis, or blood poisoning, is a potentially life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs.

<span class="mw-page-title-main">Mechanical ventilation</span> Method to mechanically assist or replace spontaneous breathing

Mechanical ventilation, assisted ventilation or intermittent mandatory ventilation (IMV) is the medical term for using a machine called a ventilator to fully or partially provide artificial ventilation. Mechanical ventilation helps move air into and out of the lungs, with the main goal of helping the delivery of oxygen and removal of carbon dioxide. Mechanical ventilation is used for many reasons, including to protect the airway due to mechanical or neurologic cause, to ensure adequate oxygenation, or to remove excess carbon dioxide from the lungs. Various healthcare providers are involved with the use of mechanical ventilation and people who require ventilators are typically monitored in an intensive care unit.

<span class="mw-page-title-main">Intensive care medicine</span> Medical care subspecialty, treating critically ill

Intensive care medicine, also called critical care medicine, is a medical specialty that deals with seriously or critically ill patients who have, are at risk of, or are recovering from conditions that may be life-threatening. It includes providing life support, invasive monitoring techniques, resuscitation, and end-of-life care. Doctors in this specialty are often called intensive care physicians, critical care physicians or intensivists.

<span class="mw-page-title-main">Acute respiratory distress syndrome</span> Human disease

Acute respiratory distress syndrome (ARDS) is a type of respiratory failure characterized by rapid onset of widespread inflammation in the lungs. Symptoms include shortness of breath (dyspnea), rapid breathing (tachypnea), and bluish skin coloration (cyanosis). For those who survive, a decreased quality of life is common.

<i>Klebsiella pneumoniae</i> Species of bacterium

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High-frequency ventilation is a type of mechanical ventilation which utilizes a respiratory rate greater than four times the normal value. and very small tidal volumes. High frequency ventilation is thought to reduce ventilator-associated lung injury (VALI), especially in the context of ARDS and acute lung injury. This is commonly referred to as lung protective ventilation. There are different types of high-frequency ventilation. Each type has its own unique advantages and disadvantages. The types of HFV are characterized by the delivery system and the type of exhalation phase.

<span class="mw-page-title-main">Hospital-acquired pneumonia</span>

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<span class="mw-page-title-main">Alcoholic lung disease</span> Human disease

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<span class="mw-page-title-main">Proning</span> Nursing technique

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References

  1. 1 2 3 Cooper, Adam S. (2021). "Oral Hygiene Care to Prevent Ventilator-Associated Pneumonia in Critically Ill Patients". Critical Care Nurse. 41 (4): 80–82. doi:10.4037/ccn2021314. PMID   34333609. S2CID   236773722.
  2. 1 2 3 4 Michetti CP, Fakhry SM, Ferguson PL, Cook A, Moore FO, Gross R (May 2012). "Ventilator-associated pneumonia rates at major trauma centers compared with a national benchmark: a multi-institutional study of the AAST". The Journal of Trauma and Acute Care Surgery. 72 (5): 1165–73. doi:10.1097/TA.0b013e31824d10fa. PMID   22673241. S2CID   19476292.
  3. 1 2 3 Cook D (2000). "Ventilator associated pneumonia: perspectives on the burden of illness". Intensive Care Medicine. 26 (Suppl 1): S31-7. doi:10.1007/s001340051116. PMID   10786956. S2CID   22849696.
  4. Koenig SM, Truwit JD (October 2006). "Ventilator-associated pneumonia: diagnosis, treatment, and prevention". Clinical Microbiology Reviews. 19 (4): 637–57. doi:10.1128/cmr.00051-05. PMC   1592694 . PMID   17041138.
  5. 1 2 Craven DE, Chroneou A, Zias N, Hjalmarson KI (February 2009). "Ventilator-associated tracheobronchitis: the impact of targeted antibiotic therapy on patient outcomes". Chest. 135 (2): 521–528. doi:10.1378/chest.08-1617. PMID   18812452.
  6. Gupta A, Gupta A, Singh TK, Saxsena A. Role of oral care to prevent VAP in mechan- ically ventilated intensive care unit patients. Saudi J Anaesth. 2016;10(1):95-97
  7. Abu-Salah T, Dhand R (September 2011). "Inhaled antibiotic therapy for ventilator-associated tracheobronchitis and ventilator-associated pneumonia: an update". Advances in Therapy. 28 (9): 728–47. doi: 10.1007/s12325-011-0051-z . PMID   21833701.
  8. Atashi V, Yousefi H, Mahjobipoor H, Bekhradi R, Yazdannik A. Effect of oral care program on prevention of ventilator-associated pneumonia in intensive care unit patients: a randomized controlled trial. Iran J Nurs Midwifery Res. 2018;23(6):486-490
  9. "Lung Bacterial Population Diversity in CAP, VAP and Health using 16S rDNA Sequencing". ResearchGate. Retrieved 2016-04-19.
  10. 1 2 Nolan TJ, Gadsby NJ, Hellyer TP, Templeton KE, McMullan R, McKenna JP, et al. (July 2016). "Low-pathogenicity Mycoplasma spp. alter human monocyte and macrophage function and are highly prevalent among patients with ventilator-acquired pneumonia". Thorax. 71 (7): 594–600. doi:10.1136/thoraxjnl-2015-208050. PMC   4941152 . PMID   27071419.
  11. Conway Morris A, Kefala K, Wilkinson TS, Dhaliwal K, Farrell L, Walsh T, et al. (July 2009). "C5a mediates peripheral blood neutrophil dysfunction in critically ill patients". American Journal of Respiratory and Critical Care Medicine. 180 (1): 19–28. doi:10.1164/rccm.200812-1928OC. PMC   2948533 . PMID   19324972.
  12. Morris AC, Brittan M, Wilkinson TS, McAuley DF, Antonelli J, McCulloch C, et al. (May 2011). "C5a-mediated neutrophil dysfunction is RhoA-dependent and predicts infection in critically ill patients". Blood. 117 (19): 5178–88. doi: 10.1182/blood-2010-08-304667 . PMID   21292772.
  13. Conway Morris A, Anderson N, Brittan M, Wilkinson TS, McAuley DF, Antonelli J, et al. (November 2013). "Combined dysfunctions of immune cells predict nosocomial infection in critically ill patients". British Journal of Anaesthesia. 111 (5): 778–87. doi: 10.1093/bja/aet205 . PMID   23756248.
  14. Marino PL (2014). Marino's the ICU book (Fourth ed.). Wolters Kluwer Health/Lippincott Williams & Wilkins. ISBN   978-1451121186.
  15. 1 2 3 4 5 6 7 8 9 10 "Pneumonia (Ventilator-associated [VAP] and non-ventilator-associated Pneumonia [PNEU]) Event" (PDF). Centers for Disease Control and Prevention. January 2015.
  16. 1 2 3 Berton DC, Kalil AC, Teixeira PJ (October 2014). "Quantitative versus qualitative cultures of respiratory secretions for clinical outcomes in patients with ventilator-associated pneumonia". The Cochrane Database of Systematic Reviews (10): CD006482. doi:10.1002/14651858.CD006482.pub4. PMID   25354013.
  17. Conway Morris A, Kefala K, Wilkinson TS, Moncayo-Nieto OL, Dhaliwal K, Farrell L, et al. (March 2010). "Diagnostic importance of pulmonary interleukin-1beta and interleukin-8 in ventilator-associated pneumonia". Thorax. 65 (3): 201–7. doi:10.1136/thx.2009.122291. PMC   2866736 . PMID   19825784.
  18. Hellyer TP, Morris AC, McAuley DF, Walsh TS, Anderson NH, Singh S, et al. (January 2015). "Diagnostic accuracy of pulmonary host inflammatory mediators in the exclusion of ventilator-acquired pneumonia". Thorax. 70 (1): 41–7. doi:10.1136/thoraxjnl-2014-205766. PMC   4992819 . PMID   25298325.
  19. Conway Morris A, Gadsby N, McKenna JP, Hellyer TP, Dark P, Singh S, et al. (November 2017). "16S pan-bacterial PCR can accurately identify patients with ventilator-associated pneumonia". Thorax. 72 (11): 1046–1048. doi:10.1136/thoraxjnl-2016-209065. PMC   5738539 . PMID   27974525.
  20. Hellyer, Thomas P.; McAuley, Daniel F.; Walsh, Timothy S.; Anderson, Niall; Conway Morris, Andrew; Singh, Suveer; Dark, Paul; Roy, Alistair I.; Perkins, Gavin D.; McMullan, Ronan; Emerson, Lydia M.; Blackwood, Bronagh; Wright, Stephen E.; Kefala, Kallirroi; O'Kane, Cecilia M. (February 2020). "Biomarker-guided antibiotic stewardship in suspected ventilator-associated pneumonia (VAPrapid2): a randomised controlled trial and process evaluation". The Lancet. Respiratory Medicine. 8 (2): 182–191. doi:10.1016/S2213-2600(19)30367-4. ISSN   2213-2619. PMC   7599318 . PMID   31810865.
  21. Navapurkar, Vilas; Bartholdson Scott, Josefin; Maes, Mailis; Hellyer, Thomas P.; Higginson, Ellen; Forrest, Sally; Pereira-Dias, Joana; Parmar, Surendra; Heasman-Hunt, Emma; Polgarova, Petra; Brown, Joanne; Titti, Lissamma; Smith, William Pw; Scott, Jonathan; Rostron, Anthony (2021). "Development and implementation of a customised rapid syndromic diagnostic test for severe pneumonia". Wellcome Open Research. 6: 256. doi: 10.12688/wellcomeopenres.17099.3 . ISSN   2398-502X. PMC   9617073 . PMID   36337362.
  22. Clark, John A.; Conway Morris, Andrew; Curran, Martin D.; White, Deborah; Daubney, Esther; Kean, Iain R. L.; Navapurkar, Vilas; Bartholdson Scott, Josefin; Maes, Mailis; Bousfield, Rachel; Török, M. Estée; Inwald, David; Zhang, Zhenguang; Agrawal, Shruti; Kanaris, Constantinos (2023-01-10). "The rapid detection of respiratory pathogens in critically ill children". Critical Care. 27 (1): 11. doi: 10.1186/s13054-023-04303-1 . ISSN   1466-609X. PMC   9831374 . PMID   36627688.
  23. Conway Morris, Andrew; Bos, Lieuwe D. J.; Nseir, Saad (June 2022). "Molecular diagnostics in severe pneumonia: a new dawn or false promise?". Intensive Care Medicine. 48 (6): 740–742. doi:10.1007/s00134-022-06722-0. ISSN   1432-1238. PMID   35552790. S2CID   248725370.
  24. Jeffrey, Mark; Denny, Kerina J.; Lipman, Jeffrey; Conway Morris, Andrew (2023-06-21). "Differentiating infection, colonisation, and sterile inflammation in critical illness: the emerging role of host-response profiling". Intensive Care Medicine. 49 (7): 760–771. doi:10.1007/s00134-023-07108-6. ISSN   1432-1238. PMID   37344680. S2CID   259221137.
  25. 1 2 Marino PL, Sutin KM, Gast P (2009). The little ICU book of facts and formulas. Philadelphia: Wolter Kluwer Health/Lippincott Williams & Wilkins. ISBN   978-0781778237.
  26. Wang L, Li X, Yang Z, Tang X, Yuan Q, Deng L, Sun X (January 2016). "Semi-recumbent position versus supine position for the prevention of ventilator-associated pneumonia in adults requiring mechanical ventilation". The Cochrane Database of Systematic Reviews. 2016 (1): CD009946. doi:10.1002/14651858.CD009946.pub2. PMC   7016937 . PMID   26743945.
  27. Zhao T, Wu X, Zhang Q, Li C, Worthington HV, Hua F (24 December 2020). "Oral hygiene care for critically ill patients to prevent ventilator-associated pneumonia". The Cochrane Database of Systematic Reviews. 2020 (12): CD008367. doi:10.1002/14651858.CD008367.pub4. PMC   8111488 . PMID   33368159.
  28. Klompas M, Speck K, Howell MD, Greene LR, Berenholtz SM (May 2014). "Reappraisal of routine oral care with chlorhexidine gluconate for patients receiving mechanical ventilation: systematic review and meta-analysis". JAMA Internal Medicine. 174 (5): 751–61. doi: 10.1001/jamainternmed.2014.359 . PMID   24663255.
  29. Lorente L, Lecuona M, Jiménez A, Mora ML, Sierra A (December 2007). "Influence of an endotracheal tube with polyurethane cuff and subglottic secretion drainage on pneumonia". American Journal of Respiratory and Critical Care Medicine. 176 (11): 1079–83. doi:10.1164/rccm.200705-761OC. PMID   17872488.
  30. Tokmaji G, Vermeulen H, Müller MC, Kwakman PH, Schultz MJ, Zaat SA (August 2015). "Silver-coated endotracheal tubes for prevention of ventilator-associated pneumonia in critically ill patients". The Cochrane Database of Systematic Reviews. 2018 (8): CD009201. doi:10.1002/14651858.CD009201.pub2. PMC   6517140 . PMID   26266942.
  31. Bo L, Li J, Tao T, Bai Y, Ye X, Hotchkiss RS, et al. (October 2014). "Probiotics for preventing ventilator-associated pneumonia". The Cochrane Database of Systematic Reviews. 10 (10): CD009066. doi:10.1002/14651858.CD009066.pub2. PMC   4283465 . PMID   25344083.
  32. Arthur LE, Kizor RS, Selim AG, van Driel ML, Seoane L (October 2016). "Antibiotics for ventilator-associated pneumonia". The Cochrane Database of Systematic Reviews. 2016 (10): CD004267. doi:10.1002/14651858.CD004267.pub4. PMC   6461148 . PMID   27763732.
  33. Grammatikos AP, Siempos II, Michalopoulos A, Falagas ME (December 2008). "Optimal duration of the antimicrobial treatment of ventilator-acquired pneumonia". Expert Review of Anti-Infective Therapy. 6 (6): 861–6. doi:10.1586/14787210.6.6.861. PMID   19053899. S2CID   22071191.
  34. Ayzac L, Girard R, Baboi L, Beuret P, Rabilloud M, Richard JC, Guérin C (May 2016). "Ventilator-associated pneumonia in ARDS patients: the impact of prone positioning. A secondary analysis of the PROSEVA trial". Intensive Care Medicine. 42 (5): 871–878. doi:10.1007/s00134-015-4167-5. PMID   26699917. S2CID   22418365.
  35. Luyt CE, Bouadma L, Morris AC, Dhanani JA, Kollef M, Lipman J, et al. (December 2020). "Pulmonary infections complicating ARDS". Intensive Care Medicine. 46 (12): 2168–2183. doi:10.1007/s00134-020-06292-z. PMC   7656898 . PMID   33175277.
  36. Chastre J, Fagon JY (April 2002). "Ventilator-associated pneumonia". American Journal of Respiratory and Critical Care Medicine. 165 (7): 867–903. CiteSeerX   10.1.1.492.8006 . doi:10.1164/ajrccm.165.7.2105078. PMID   11934711.
  37. Sharpe JP, Magnotti LJ, Weinberg JA, Brocker JA, Schroeppel TJ, Zarzaur BL, et al. (July 2014). "Gender disparity in ventilator-associated pneumonia following trauma: identifying risk factors for mortality". The Journal of Trauma and Acute Care Surgery. 77 (1): 161–5. doi:10.1097/TA.0000000000000251. PMID   24977772. S2CID   1349973.
  38. 1 2 Maes M, Higginson E, Pereira-Dias J, Curran MD, Parmar S, Khokhar F, et al. (January 2021). "Ventilator-associated pneumonia in critically ill patients with COVID-19". Critical Care. 25 (1): 25. doi: 10.1186/s13054-021-03460-5 . PMC   7797892 . PMID   33430915.
  39. 1 2 Razazi K, Arrestier R, Haudebourg AF, Benelli B, Carteaux G, Decousser JW, et al. (December 2020). "Risks of ventilator-associated pneumonia and invasive pulmonary aspergillosis in patients with viral acute respiratory distress syndrome related or not to Coronavirus 19 disease". Critical Care. 24 (1): 699. doi: 10.1186/s13054-020-03417-0 . PMC   7747772 . PMID   33339526.
  40. Roquilly A, Jacqueline C, Davieau M, Mollé A, Sadek A, Fourgeux C, et al. (June 2020). "Alveolar macrophages are epigenetically altered after inflammation, leading to long-term lung immunoparalysis". Nature Immunology. 21 (6): 636–648. doi:10.1038/s41590-020-0673-x. PMID   32424365. S2CID   218682792.
  41. Scaravilli, Vittorio; Guzzardella, Amedeo; Madotto, Fabiana; Beltrama, Virginia; Muscatello, Antonio; Bellani, Giacomo; Monti, Gianpaola; Greco, Massimiliano; Pesenti, Antonio; Bandera, Alessandra; Grasselli, Giacomo (December 2022). "Impact of dexamethasone on the incidence of ventilator-associated pneumonia in mechanically ventilated COVID-19 patients: a propensity-matched cohort study". Critical Care. 26 (1): 176. doi: 10.1186/s13054-022-04049-2 . ISSN   1364-8535. PMC   9191402 . PMID   35698155.
  42. Martínez-Martínez, María; Plata-Menchaca, Erika P.; Nuvials, Francesc X.; Roca, Oriol; Ferrer, Ricard (December 2021). "Risk factors and outcomes of ventilator-associated pneumonia in COVID-19 patients: a propensity score matched analysis". Critical Care. 25 (1): 235. doi: 10.1186/s13054-021-03654-x . ISSN   1364-8535. PMC   8258490 . PMID   34229747.
  43. Conway Morris, Andrew; Kohler, Katharina; De Corte, Thomas; Ercole, Ari; De Grooth, Harm-Jan; Elbers, Paul W. G.; Povoa, Pedro; Morais, Rui; Koulenti, Despoina; Jog, Sameer; Nielsen, Nathan; Jubb, Alasdair; Cecconi, Maurizio; De Waele, Jan; for the ESICM UNITE COVID investigators (December 2022). "Co-infection and ICU-acquired infection in COIVD-19 ICU patients: a secondary analysis of the UNITE-COVID data set". Critical Care. 26 (1): 236. doi: 10.1186/s13054-022-04108-8 . ISSN   1364-8535. PMC   9347163 . PMID   35922860.

Further reading