Ventilator associated pneumonias

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Ventilator associated pneumonias

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Ventilator associated pneumonias

  1. 1. Dr.T.V.Rao MD<br />Ventilator-Associated Pneumonias (VAP)<br />
  2. 2. Pneumonia can be a life threatening condition<br />Nosocomial pneumonia (NP), hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP), is an important cause of morbidity and mortality in hospitalized patients. One of the factors contributing to a high mortality rate of HAP and VAP could be antibiotic resistance among the causative agents. <br />
  3. 3. Ventilator Associated Pneumonia (VAP)<br />Ventilator Associated Pneumonia (VAP) is pneumonia occurring in a patient within 48 hours or more after intubation with an endotracheal tube or tracheostomy tube and which was not present before. It is also the most common and fatal infection of ICU<br />
  4. 4. Ventilator Associated Pneumonia (VAP)<br />VAP is the 2nd most common nosocomial infection = 15% of all hospital acquired infections<br />Incidence = 9% to 70% of patients on ventilators<br />Increased ICU stay by several days<br />Increased avg. hospital stay 1 to 3 weeks<br />Mortality = 13% to 55%<br />Centers for Disease Control and Prevention, 2003. <br />; <br />
  5. 5. Challenge and Controversy<br /> The diagnosis and management of VAP remains one of the most controversial and challenging topics in management of critically ill patients.”<br />
  6. 6. Centres for Disease and Control<br />The diagnosis of pneumonia in mechanically ventilated patients is difficult, and still there is no "gold-standard" diagnostic method. It is usually based on the combination of clinical, radiological, and microbiological criteria defined by Centres for Disease and Control (CDC)<br />
  7. 7. 7<br />Incidence<br />It is often difficult to define the exact incidence of HAP and VAP, because there may be an overlap with other lower respiratory tract infections, such as tracheobronchitis, especially in mechanically ventilated patients)<br />The exact incidence of HAP is usually between 5 and 15 cases per 1,000 hospital admissions depending on the case definition and study population; the exact incidence of VAP is 6- to 20-fold greater than in nonventilated patients<br />
  8. 8. Mechanical ventilation predisposes to VAP<br />HAP accounts for up to 25% of all ICU infections <br />In ICU patients, nearly 90% of episodes of HAP occur during mechanical ventilation <br />
  9. 9. Nosocomial infection are Multidrug Resistant<br />Many patients with HAP, VAP, and HCAP are at increased risk for colonization and infection with MDR pathogens<br />HAP and VAP are a frequent cause of nosocomial infection that is associated with a higher crude mortality than other hospital-acquired infections<br />9<br />
  10. 10. Definition– Ventilator Associate Pneumonia<br />Pneumonia that develops in someone who has been intubated<br />-Typically in studies, patients are only included if intubated greater than 48 hours<br />-Early onset= less than 4 days<br />-Late onset= greater than 4 days<br />Endotracheal intubation increases risk of developing pneumonia by 6 to 21 fold<br />Accounts for 90% of infections in mechanically ventilated patients<br />. <br />
  11. 11. Prevalence of VAP<br />Occurs in 10-20% of those receiving mechanical ventilation for greater than 48 hours<br />Rate= 14.8 cases per 1000 ventilator days<br />
  12. 12. When does VAP occur?<br />Cook et al showed . . .<br />40.1% developed before day 5<br />41.2% developed between days 6 and 10<br />11.3% developed between days 11-15<br />2.8% developed between days 16 and 20<br />4.5% developed after day 21<br />Cook et al. Incidence of and risk factors for ventilator-associated pneumonia<br />in critically ill patients.<br />
  13. 13.
  14. 14. Time frame of intubation and risk<br />Risk of pneumonia at intubation days<br />3.3% per day at day 5<br />2.3% per day at day 10<br />1.3% per day at day 15 <br />.<br />
  15. 15. Who gets VAP? (Risk factors)<br />Study of 1014 patients receiving mechanical ventilation for 48 hours or more and free of pneumonia at admission to ICU<br />Increased risk associated with admitting diagnosis of :<br />Burns (risk ratio=5.09)<br />Trauma (risk ratio=5.0)<br />Respiratory disease (risk ratio=2.79)<br />CNS disease (risk ratio=3.4)<br />
  16. 16. 16<br />
  17. 17. PAHOGENESIS<br />The pathogenesis of ventilator-associated pneumonia usually requires that two important processes take place: <br />Bacterial colonization of the aero digestive tract <br />The aspiration of contaminated secretions into the lower airway.<br />17<br />
  18. 18. 18<br />
  19. 19. Etiology<br />Bacteria cause most cases of HAP, VAP, and HCAP and many infections are polymicrobial; rates are especially high in patients with ARDS<br />19<br />
  20. 20. VAP Etiology<br />Most are bacterial pathogens, with Gram negative bacilli common:<br />Pseudomonas aeruginosa<br />Proteus spp<br />Acinetobacter spp<br />Staphlococcus aureus<br />Early VAP associated with non-multi-antibiotic-resistant organisms<br />Late VAP associated with antibiotic-resistant organism<br />
  21. 21. Common and Uncommon isolates in VAP<br />HAP, VAP, and HCAP are commonly caused by aerobic gram-negative bacilli, such as P. aeruginosa, K. pneumoniae, and Acinetobacter species, or by gram-positive cocci, such as S. aureus, much of which is MRSA; anaerobes are an uncommon cause of VAP<br />
  22. 22. Drug resistance a concern in Ventilator Associated Pneumonias<br /> A. baumanni was the most common isolated pathogen many of them were multidrug-resistant (MDR) or pan drug-resistant (PDR). The other common isolated pathogens were K. pneumoniae, P. aeruginosa and methicillin-resistant S. aureus (MRSA).<br />
  23. 23. 23<br />Other Isolates in Ventilator associated Pneumonias<br />Pseudomonas aeruginosa.<br />the most common MDR gram-negative bacterial pathogen causing HAP/VAP, has intrinsic resistance to many antimicrobial agents<br />Klebsiella, Enterobacter, and Serratia species.<br />Klebsiella species<br />intrinsically resistant to ampicillin and other aminopenicillins and can acquire resistance to cephalosporins and aztreonam by the production of extended-spectrum –lactamases (ESBLs)<br />However ESBL-producing strains remain susceptible to carbapenems<br />Enterobacter species<br />Citrobacter and Serratia species<br />
  24. 24. Acinetobacter speciesAcinAcinetobacter species<br />Acinetobacter species<br />More than 85% of isolates are susceptible to carbapenems, but resistance is increasing <br />Stenotrophomonas maltophilia, and Burkholderia cepacia: <br />resistant to carbapenems <br />24<br />
  25. 25. Acinetobacter species a Growing Concern<br />Acinetobacter species<br />More than 85% of isolates are susceptible to carbapenems, but resistance is increasing <br />An alternative for therapy is sulbactam<br />Stenotrophomonas maltophilia, and Burkholderia cepacia: <br />Resistant to carbapenems <br />Susceptible to trimethoprim–sulfamethoxazole, ticarcillin–clavulanate, or a fluoroquinolone <br />
  26. 26. 26<br />Staphylococcus aureus and Streptococcus pneumoniae <br />Methicillin-resistant Staphylococcus aureus<br />vancomycin-intermediate S. aureus<br />sensitive to linezolid <br />linezolid resistance has emerged in S. aureus, but is currently rare <br />Streptococcus pneumoniae and Haemophilus influenzae.<br />sensitive to vancomycin or linezolid, and most remain sensitive to broadspectrum quinolones <br />
  27. 27. L. Pneumophila and environment <br />Rates of L. pneumophila vary considerably between hospitals and disease occurs more commonly with serogroup 1 when the water supply is colonized or there is ongoing construction<br />27<br />
  28. 28. Influenza too can cause VAP<br />Nosocomial virus and fungal infections are uncommon causes of HAP and VAP in immunocompetent patients. Outbreaks of influenza have occurred sporadically and risk of infection can be substantially reduced with widespread effective infection control, vaccination, and use of anti influenza agents<br />28<br />
  29. 29. Fungal pathogens can cause VAP<br />Fungal pathogens.<br />Aspergillus species<br />Candida albicans<br />
  30. 30. Pathogenesis – Entry of Pathogens<br />Where do the bacteria come from?<br />Tracheal colonization- via oropharyngeal colonization or GI colonization<br />Ventilator system<br />How do they get into the lung?<br />Breakdown of normal host defenses<br />Two main routes<br />Through the tube<br />Around the tube- microaspiration around ETT cuff<br />
  31. 31. Causative Organisms<br />Early onset:<br />Hemophilus influenza<br />Streptococcus pneumoniae<br />Staphylococcus aureus (methicillin sensitive)<br />Escherichia coli<br />Klebsiella pneumoniae<br />Late onset:<br />Pseudomonas aeruginosa<br />Acinetobacter spp.<br />Staphylococcus aureus (methicillin resistant)<br />Most strains responsible for early onset VAP are antibiotic sensitive. Those responsible for late onset VAP are usually multiple antibiotic resistant<br />Am J Resp Crit Care (1995)<br />
  32. 32. Oropharyngeal colonization can be source of VAP<br />Scannapieco et al showed a transition in the colonization of dental plaques in patients in the ICU<br />Control=25 subjects presenting to preventive dentistry clinic<br />Study group=34 noncardiac patients admitted to medical ICU at VA hospital (sampled within 12 hours of admission and every third day)<br />
  33. 33. Gastrointestinal colonization<br />Increased gastric pH leads to bacterial overgrowth<br />Reflux can then lead to colonization of oropharynx<br />Use of antacids and H2 blockers associated with GI colonization<br />Safdar et al. The pathogenesis of ventilator-associated pneumonia: <br />its relevance to developing effective strategies for prevention<br />
  34. 34. Viral Pathogens<br />Outbreaks of HAP, VAP, and HCAP due to viruses, such as influenza, parainfluenza, adenovirus, measles, and respiratory syncytial virus have been reported and are usually seasonal. <br />Influenza, pararinfluenza, adenovirus, and respiratory syncytial virus account for 70% of the nosocomial viral cases of HAP,VAP, and HCAP<br />
  35. 35. Multidrug resistant organisms are associated with …<br />The prevalence of MDR pathogens varies by patient population, hospital, and type of ICU, which underscores the need for local surveillance data<br />MDR pathogens are more commonly isolated from patients with severe, chronic underlying disease, those with risk factors for HCAP, and patients with late-onset HAP or VAP<br />35<br />
  36. 36. Supine patients<br />Studies using radioactive labeling of gastric contents showed that radioactive counts were higher in larynx of supine patients<br />One of the studies showed the same organisms in stomach, pharynx and endobronchial samples1<br />Drakulovic et al. studied rate of VAP and found it to be higher in supine compared to semi-recumbent patients<br />
  37. 37. Tracheal colonization<br />Cendrero et al:<br />25 patients of 110 studied developed VAP<br />In these 25 patients, 22 had their trachea colonized 3.63 days prior to diagnosis of VAP<br />17 of the 22 had oropharyngeal colonization prior to trachea<br />Only 7 had prior colonization of the stomach<br />
  38. 38. Infected biofilms too contribute to increased incidence of VAP<br />Infected biofilm in the endotracheal tube, with subsequent embolization to distal airways, may be important in the pathogenesis of VAP <br />
  39. 39. ET tubes increases Biofilm formation<br />Exopolysaccharide outer layer with quiescent bacteria within<br />Difficult for bacteria to penetrate outer layer and bacteria within resistant to bactericidal effects of bacteria<br />
  40. 40. Difficult to kill biofilm organismsComparison of MBC of antibiotics for tracheal isolates vs. biofilm isolates<br />
  41. 41. 41<br />Clinical Strategy in Diagnosis of VAP<br />Clinical Strategy<br />The presence of a new or progressive radiographic infiltrate<br />At least two of three clinical features <br />fever greater than 38_C, <br />leukocytosis or leukopenia, <br />purulent secretions<br />Represents the most accurate combination of criteria for starting empiric antibiotic therapy. <br />
  42. 42. Pathogens in VAP (1) <br />Pathogens that cause VAP differ depending on whether the condition occurs early (less than 96 hours after intubation or admission to ICU) or late (greater than 96 hours after intubation or admission to ICU)<br />
  43. 43. Pathogens in VAP (2)<br />Early–Onset Pneumonia (< 96 hours of intubation or ICU admission)<br />Community-acquired <br />Pathogens:<br />Streptococcus pneumoniae<br />Haemophilus influenzae<br />Staphylococcus aureus<br />Antibiotic-sensitive ?<br />
  44. 44. Pathogens in VAP (3)<br />Late-Onset Pneumonia(> 96 hours of intubation or ICU admission)<br />Hospital-acquired <br />Pathogens:<br />Pseudomonas aeruginosa<br />Methicillin resistant Staphylococcus aureus (MRSA)<br />Acinetobacter<br />Enterobacter<br />Antibiotic-resistant ???<br />
  45. 45. Diagnosis is imprecise and usually based on a Combination of<br />Clinical factors - fever or hypothermia; change in secretions; cough; apnea/ bradycardia; tachypnea<br />Microbiological factors - positive cultures of blood/sputum/tracheal aspirate/pleural fluids<br />CXR factors - new or changing infiltrates<br />
  46. 46. Strategies in Diagnosis in VAP are multifaceted<br />Clinical Strategy<br />Bacteriologic Strategy<br />Comparing Diagnostic Strategy<br />46<br />
  47. 47. Gram stain is highly sensitive<br />Sputum or tracheal suction gram stain <br />NO ORGANISMS<br />in non-neutropenic pts.<br />NO HAP/VAP 94%<br />
  48. 48. Gram staining of secretions are useful in early decisions<br />The upper respiratory tract of patients is colonized with potential pulmonary pathogens a few hours after intubation. A positive Gram's stain may guide the initial antibiotic therapy. However prior antibiotic and corticosteroid therapy can reduce the sensitivity of this technique<br />
  49. 49. Bacterial culture of tracheal secretion<br />Qualitative culture <br /> - non specific<br />Semi-quantitative culture <br /> - low specificity<br />Quantitative culture : TS, BAL, PSB<br /> - increase specificity <br />
  50. 50. Specimen collection for Optimal Results<br />Distal airway samples may be obtained by using bronchoscopic or nonbronchoscopic techniques. With nonbronchoscopic techniques, a catheter is blindly advanced through the endotracheal tube or tracheostomy and wedged in the distal airway. Various sampling methods include blind bronchial suction (BBS), blind BAL, and blind PSB sampling. <br />
  51. 51. Semiquantitative<br />1+ :rare <10 colonies/plate<br />2+: few 10-102 colonies/plate<br />3+: moderate >102-3 colonies/plate<br />4+: numerous >103-4 colonies/plate<br />5+: numerous >104 colonies/plate<br />
  52. 52. Tracheal aspirates are valuable specimens<br />A reliable tracheal aspirate Gram stain can be used to direct initial empiric antimicrobial therapy and may increase the diagnostic value of the CPIS<br />A negative tracheal aspirate (absence of bacteria or in-flammatory cells) in a patient without a recent (within 72 hours) change in antibiotics has a strong negative predictive value (94%) for VAP and should lead to a search for alternative sources of fever<br />52<br />
  53. 53. Bacteriologic Strategy<br />Quantitative cultures can be performed on endotracheal aspirates or samples collected either bronchoscopically or nonbronchoscopically, and each technique has its own diagnostic threshold and methodologic limitations. The choice of method depends on local expertise, experience, availability, and cost<br />
  54. 54. Bacterial culture of tracheal secretion<br />Qualitative culture <br /> - non specific<br />Semi-quantitative culture <br /> - low specificity<br />Quantitative culture : TS, BAL, PSB<br /> - increase specificity <br />
  55. 55. Collection of bronchial Secretions<br />Distal airway samples may be obtained by using bronchoscopic or nonbronchoscopic techniques. With nonbronchoscopic techniques, a catheter is blindly advanced through the endotracheal tube or tracheostomy and wedged in the distal airway. Various sampling methods include blind bronchial suction (BBS), blind BAL, and blind PSB sampling. <br />
  56. 56. Qualitative and quantitative <br />Qualitative endotracheal aspirates are easy to obtain but have a high false-positive rate in ICU patients because of airway colonization. When quantitative endotracheal-aspirate cultures are used, a cutoff value of 106 is the most accurate, with a sensitivity of 38-82% and a specificity of 72-85%<br />
  57. 57. False negative – False Positive Results<br />Investigators reported that the clinical diagnosis of VAP is associated 30–35% false-negative and 20–25% false-positive results . And also, ICU patients do not always have systemic signs of infection due to their underlying disease (chronic renal failure)<br />
  58. 58. Other Supporting Bacterial Cultures<br />Bacteraemia and positive pleural effusion cultures are generally considered to be able to identify the organisms causing thepneumonia, if no other source of infection is found. Therefore,most experts recommend that investigation of suspected VAP shouldinclude taking two sets of blood samples for culture and tappingpleural  > 10 mm, even though spread to the blood orpleural space occurs in < 10% of VAP<br />
  59. 59. Multiresistant pathogens in Ventilator associated pneumonias<br />The incidence of multiresistant pathogens is also closely linked to local factors and varies widely from one institution toanother. Consequently, each ICU must continuously collect meticulousepidemiologic data<br />
  60. 60. Uncommon microbes are often missed<br />Legionella species , anaerobes fungi viruses, and even Pneumocystis carinii should be mentionedas potential causative agents but are not considered to be commonin the context of pneumonia acquired during MV. However, severalof these causative agents may be more common and potentially underreportedbecause of difficulties involved with the diagnostic<br />
  61. 61. 61<br />Comparing Diagnostic Strategy<br />A patients with suspected VAP should have a lower respiratory tract sample sent for culture, and extrapulmonary infection should be excluded, as part of the evaluation before administration of antibiotic therapy<br />If there is a high pretest probability of pneumonia, or in the 10% of patients with evidence of sepsis, prompt therapy is required, regardless of whether bacteria are found on microscopic examination of lower respiratory tract samples<br />
  62. 62. Microbiologists / Physicians should consider other Diagnostic results<br />Pugin et al. proposed to combine the seven variables (temperature, leukocytes, tracheal aspirate volume and purulence of tracheal secretions, chest X-ray, oxygenation-PaO2/FiO2- and semi quantitative culture of tracheal aspirate) for the diagnosis of VAP, defined as clinical pulmonary infection score (CPIS) <br />
  63. 63. Mortality<br />Mortality<br />Inappropriate<br />Mortality<br />Appropriate<br />Early<br />Mortality<br />Evidence-based early and appropriate therapy in VAP<br />
  64. 64. Best option in choosing Antibiotics<br />Considerations in making selection<br />Setting (community, NH, hospital)<br />Suspected organism (GNRs, GPCs)<br />Host factors (immunosuppression)<br />Local susceptibility patterns<br />Initial empiric and broad; subsequent narrowing<br />Concept is to not miss the organism with initial coverage and then de-escalate when able<br />
  65. 65. Continuous Removal of Subglottic Secretions<br /><ul><li>Use an ET tube with continuous suction through a dorsal lumen above the cuff to prevent drainage accumulation</li></li></ul><li>HOB Elevation<br />HOB at 30-45oKeep the HOB elevated to at least 30 degrees unless medically contraindicated<br />
  66. 66. Condensate management<br />Heat-moisture exchanger<br />Theoretical advantage=prevents bacterial colonization of tubing<br />Studies= Mixed results<br />Disadvantage=increases dead space and resistance to breathing<br />Heated wire to elevate temp of inspired air<br />Advantage=Decreases condensate formation<br />Disadvantage=Blockage of ET tube by dried secretions<br />CDC.gov. Guidelines for preventing health-care-associated pneumonia, 2003.<br />
  67. 67. Condensate management<br />Nurse and provider education regarding management of tubes with patient position change or manipulation of bed to ensure that condensate in tubing does not flow towards patient<br />
  68. 68. Handwashing<br />What role does handwashing play in nosocomial pneumonias? The greatest role<br />
  69. 69. VAP Prevention<br />Wash hands before and after suctioning, touching ventilator equipment, and/or coming into contact with respiratory secretions.<br />
  70. 70. Epidemiological data differs from situations<br />The incidence of multiresistant pathogens is also closely linked to local factors and varies widely from one institution toanother. Consequently, each ICU must continuously collect meticulousepidemiologic data<br />
  71. 71. Treating patient with VAP is complex<br />Successful treatment of patients with VAP remains a difficult and complex undertaking. Despite broad clinical experience withthis disease, no consensus has been reached concerning issuesas basic as the optimal antimicrobial regimen or its duration.In fact, to date, evaluation of various antimicrobial strategiesfor the treatment of bacterial VAP has been difficult for severalreasons. <br />
  72. 72. Summary<br />Clinical evidence suggests that early use of appropriate empiric antibiotic therapy improves patient outcomes in terms of:<br />reduced mortality <br />reduced morbidity<br />reduced duration of hospital stay<br />
  73. 73. Created by Dr.T.V.Rao MD for ‘e’ learning for Medical Professionals<br />Email<br />doctortvrao@gmail.com<br />

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