ventilator associated pneumonia by dr imran
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VENTILATOR ASSOCIATED PNEUMONIA
DR IMRAN GAFOOR DR DEBASHISH DHAR
DEPTT OF CRITICAL CARE & EMERGENCY MEDICINE
SIR GANGARAM HOSPITAL
DEFINITIONS
VAP : ventilator associated pneumonia is a nosocomial pneumonia which develops in ICU patients who have been tracheally intubated/MV ≥ 2 days.
VAT : ventilator associated tracheobronchitis,↑
in volume & purulence of resp secretions,fever
leucocytosis but no radiological infiltrates.
HCAP : health care associated pneumonia. RISK FACTORS - hospitalzn. For ≥ 2 days within preceding
90 days, - residencein nursing home or extended
care facility, - home infusion therapy (antibiotics) - chronic dialysis within 30 days, - home wound care - family member with MDR pathogens
OTHER CLASSIFICATION : PRIMARY ENDOGENOUS PNEUMONIA – causative micro-organisms are isolated in surv- eillance cultures on admission. SECONDARY ENDOGENOUS PNEUMONIA- causative micro-organisms later on colonize
oropharynx/GIT & reach lower resp tract EXOGENOUS PNEUMONIA –
pt is not a previous carrier but colonised by ventilator tubes ,bronchoscopes,humidifiers etc.
EARLY vs LATE ONSET VAP : EARLY ONSET (<4 days) – antibiotic sensitive,better
prognosis LATE ONSET (5 days or more) – MDR pathogens,increased
mortality There were no significant differences in the prevalence of
potential MDR pathogens associated with early-onset or
late-onset VAP, even in subjects with prior antibiotics.
Empiric therapy for early-onset VAP should also include
agents likely to be effective for potential MDR
pathogens.
Respir Care. 2013
Jul;58(7):1220-5.
TROVILLET et al found that two variables were significant for predicting infection with MDR VAP :
- mechanical ventilation ≥ 7 days - prior antibiotic use esp broad
spectrum EPIDEMIOLOGY : second most common nosocomial infection
but leading cause of attributable mortality (33-50%)
INCIDENCE IN INDIA :-
Incidence of HAP in india is 53.9%.
Incidence of VAP in india is 8.95/1000
ventilator days.
Mortality rate(attributable) is 37% -
47.3%
Park Es et al Am j inf
control(2000)
VAP IN SGRH ICU (2012)
jan feb mar apr may june july aug sep oct nov dec0
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Series 1Column1
• It is estimated that 9-27% of patient undergoing
MV for > 2 days are affected by VAP.. Cook et al demonstrated that,risk of VAP is
3% on first 5 days of MV,2% from 5-10 days,&
1% for remaining days.MORTALITY : Several cross matching studies
have estimated that one third to half of all VAP related deaths are result of pseudomonas/acinetobacter pneumonia with bacteremia.
- mortality is inversely related to adequacy of initial empirical thereapy.
- Correct & prompt treatment of pneumonia results in better patient survival.
- Inappropriate therapy is strongly associated with worse survival.
PATHOGENESIS : * Pulmonary aspiration of
colonised (whether endo/exogenous) oropharyngeal secretions across tracheal tube cuff is the main pathogenic mechanism for development of VAP.
* Tracheal intubation is the “conditio sine qua non” for development of pneumonia because it
facilitates aspiration of pathogens & hinders
intrinsic respiratory defenses. * Normally ETT has ‘HVLP’ cuff,the
potential diameter of which is two to three times larger than tracheal diameter,so,when tracheal cuff
is inflated within trachea,folds invaraibly form along cuff surface,causing consistent micro/macro aspiration of oropharyngeal secretions.
* ETT is commonly made of PVC & bacteria easily adhere to its internal surface forming a complex structure called BIOFILM (sessile
bacteria embedded within a self produced
exopolysaccharide matrix) * ETT biofilm is difficult to eradicate &
constitutes a persistent source of colonization.
SOURCES OF COLONIZATION : - hands of ICU staff - colonised bronchoscopes - water supply
- respiratory equipments - humidifiers - ventilator temp sensors - nebulizers - contaminated environment.- In critically ill patients endogenous oral
flora shifts early to aerobic gram – pathogens (pse-
udomonas,MRSA),pulmonary aspiration of
which leads to pneumonia.
* Azarpazhooh et al showed that improved oral
hygiene & frequent professional oral health
care reduces progression or occurrence of
respiratory infection among patients in ICU.
* Orotracheal as compared to nasotracheal intu-
bation is associated with a decreased incidence
of sinusitis & thus VAP. IMPAIREMENT OF RESPIRATORY
DEFENSES DURING CRITICAL ILLNESS & TRACHEAL INTUBATION : - no protection from adduction of
true/false vocal cords.
- no protection from epiglottis - cough not possible - tracheally intubated patients have very
low muco ciliary velocity (0.8-1.4mm/min)–
higher risk for pulmonary complication. - Temporary immunoparalysis during
early course of ICU stay (low levels of HLA-
DR expression on monocytes),may
predispose to colonization.
ETIOLOGIC AGENTS : * VAP is commonly caused by aerobic gram – bacilli(peudomonos,E.coli,klebsiella,acine- tobacter),while S.AUREUS is predominant gram + organism.• EPIC-II study confirmed that pseudomonos & staph aureus are most common isolated patho- gens in ICU. UNDERLYING DISEASES : - patients with COPD have higher risk for H.infl, moraxella,pseudomonos,pneumococcus, aspergillus
In a study of nosocomial pneumonia in 51 ICU patients in india,the most commonly isolated organisms were P.auroginosa(20%), Acinetobacter spp (38%),klebsiella(23%),
MRSA(5%).The data also clearly demonstrate that the incidence
and prevalence of multidrug-resistant pathogens arerising in Asian countries. A. baumannii–calcoaceticus
complex is emerging as a major pathogen in
most of
the ICUs in these countries. MRSA, although present,
is not as big a problem as in the Western world; doi:10.1016/j.ajic.2007.05.011
- Candida & aspergillus are m/c isolated fungi in
immunocompromised.- Recent reviews show that candida in
respiratory samples demonstrate only colonosation rather than pneumonia.
- Viruses causing VAP : HSV-I,CMV- PREVENTIVE STRATEGIES FOR
NOSOCOMIAL PNEUMONIA : 1) Implementation ,as VAP bundle,of noso- comial pneumonia preventive strategies that have proven efficacy in reducing
mo- rbidity & mortality.
2) Implementation of education programmes
(respiratory care physicians & nurses being
primary recepients),& frequent performance feedbacks & compliance assesment.
3) Strict alcohol based hand hygiene.4) Avoidance of tracheal intubation & use of
NIV when indicated(acute exacebn. of COPD, acute hypoxemic resp
failure,immunocomp. with pulmonary infiltrates) -Recent reports emphasize role of
NIV in preventing re-intubation in recently
extubated pts at risk for relapse & respiratory
failure.
5) Daily sedation vacation & implementation of weaning protocols.
6) No ventilatory circuit tube changes unless soiled or damaged.
7) Use of tracheal tubes with cuff made of novel materials(polyurethane; & LVLP cuffs made of silicone &latex) & shape(conical)
8)Application of low level PEEP(5-8cm H2O)during tracheal intubation.
9) Use of silver coated ETT – NASCENT trial concluded that silver coated ETT has ↓ incidence of VAP,↓ mortality in
pts with VAP,is cost effective & has greatest impact during first 10 days.
10) Aspiration of subglottic secretions(every 4-6hrs)
11) Internal cuff pressure maintained within 25-30
cm H2O & carefully controlled during transport of patients outside ICU.
12) Earlier tracheostomised pts (mean~7 days)
had shorter length of M/V & ICU stay,a ↓trend
towards pneumonia but no survival benefit as
compared to late tracheostomy(mean~14 days)
13) Routine saline instillation before tracheal suctioning not recommended
14) Intubated pts should be kept in semi-recumbent position(30-45°),rather than supine to prevent aspiration;especially when enterally fed.
15) Continuous lateral rotation of bed helps to reduce extravascular lung water,improveV/Q
& enhance mobilization of secretions.16) Post pyloric feeding in patients with
impaired gastric emptying17) Risk of VAP associated with early
enteral feeding didn`t translate into ↑ risk of death,so,early enteral feeding advised.
18) Stress ulcer prophylaxis in high risk pts(coagulopathy,↑ duration of M/V,h/o
GI bleed.19) Oral care with 2% chlorhexidine.20) SELECTIVE CONTANINATION OF DIGESTIVE
TRACT (SDD) : - consists of nonabsorbable antibio. Against gram – (tobramycin.polymyxin E) +
nystatin/ ampho B for candida administered into GI to prevent oropharyngeal & gastric
colonization. - SDD reduces incidence of VAP & it’s the only strategy that has shown survival benefit
- SDD may promote growth of MRSA & enterococcus,so,its highly recommended to
conduct appropriate surveillance of antibiotic resistance pattern.
21) Use of probiotics is promising but additional
evidence required.DIAGNOSIS : - fever,tachycardia,leucocytosis – too
nonspecific - tachypnea & consolidation – more
specific - in elderly & immunocomp. Lethargy &
confusion – main symptoms
An imaginary vertical line from the sternal notch to the mouth, passing through the middle of the trachea should be used as a surface landmark in order to identify an orientation that could prevent
aspiration of oropharyngeal contents across the
cuff and improve drainage of airway scretions. - Lateral slight-Trendelenburg position
achieved with the bed tilted few degrees below horizontal
Current Opinion in Critical Care 2011,17:57–63
- Chest x rays : difficult to interpret,limited technical quality,misses subtle lung infiltrates.
- D/d for infiltrates : - cardio/non cardiogenic pulmo.
Edema - atelectasis - pulmonary contusions - no radiographic sign has d/g accuracy of
>68%- Air bronchograms or alveolar opacities in
pts without ARDS co-related well with pneumonia.
- Pleural effusion seen with H.infl>pneumoco pneumonia
- diarrhea/abdominal pain – legionella p.- Otitis media /pharyngitis – M.pneumonia- Herpes labialis – pneumococcal- Ecthyma gangrenosum – pseudomonos
septicemia- NOTE : >30 bpm & Na < 130 during
admission predict poor outcome.- CAVITATIONS : - multiple cavitory nodules – rt sided
endocarditis - rapid – gram (–) pneumonia - subacute – anaerobic/mycobacterial chronic – carcinoma,lymphoma,wegners
granulomatosis
CLINICAL PULMONARY INFECTION SCORE (CPIS) :
CRITERION 0 1 2 tracheal secn. (-) not purulent
purulent x- ray infiltrates NO DIFFUSE
LOCALISED temp °C ≥36.5&≤38.4 ≥38.5&≤38.9
≥39or≤36 leucocytes ≥4000&≤11000 <4000or>11000
+immature
neutro>50% PaO2/FiO2 >240 or ARDS ≤240,noARDS
microbio (-) (+)
CPIS ≥ 6 is regarded as threshold for pneumonia but value remains to be validated.
QUANTITATIVE CULTURES OF ENDOTRACHEAL ASPIRATES MAY HAVE AN ACCEPTABLE DIAGNOSTIC ACCURACY.
Current d/g threshold for tracheal aspirates is
10-10^ CFU/ml
“ “ “ “ contaminants is
10 CFU/ml
“ “ “ “ BAL is 10 CFU/ml
“ “ “ “ PBS is 10³ CFU/ml
- NON INFECTIOUS CAUSES OF FEVER/INFILTRATES MIMICKING NOSOCOMIAL PNEUMONIA :
- chemical pneumonitis - atelectasis - pulm embolism - ARDS - pulmomary hemorrhage - lung contusion - infiltrative tumour - radiation pneumonitis - drug reaction - BOOP
MOST RECENT IMPROVEMENTS IN D/G :
* direct antibiogram using E test strips
applied directly to resp samples have
proved to be reliable,effective &
anticipate susceptibility by
≥ 48 hrs
* q PCR for mecA gene - for MRSA
pneumonia
Diagnostic strategies for hospital acquired pneumonia :
- new or progressive chest infiltrate + atleast 2 of
3 clinical criteria(fever>38°c,leucocytosis or leucopenia,purulent secretions) represent beginning of diagnostic procedures
- clinical,non invasive semiquantative strategy
major drawback is high sensitivity of semi quantative culture results which leads to over estimation of incidence of nosocomial pneumonia.
Invasive and quantitative culturing strategy for VAP :
- strongly recommended that d/g sampling of
respiratory tract be obtained before starting any new antibiotic or changing previous antimicrobial therapy.
PRACTICAL IMPLEMENTATION OF A DIAGNOSTIC STRATEGY
STEP I : pt admitted/intubated for> 2 days,with no evident alternative foci of infection with atleast 2 of 3 criteria :-
- fever > 37.8°c or hypothermia < 36°c
- TLC >12000/µl or <4000/µl - purulent respiratory secretions ↓ with new infiltrates in chest x ray : if yes(NP/VAP)||| if no (VAT)
STEP II : before initiating new empirical antibiotics ,collect sample as follows :-
a) expectoration b) tracheo-bronchial aspirate c) BAL or mini –BAL d) PBS - 2 blood cultures - pleural fluid sample for parapneumonic
effusion - legionella/pneumococcal antigens in
urine - CBC/electrolytes/RFT/LFT/procal/ABG/ CRP
STEP III : calculate CPIS (TO IMPROVE OBJECTIVE ASSESMENT OF CLINICAL PARAMETERS)
TREATMENT :- most frequently isolated organisms are
s.aureus,pseudomonos f/b enterobacteriacea(e coli,klebsiella,enterobacter) then gram – as acinetobacter,stenotrophomonas,burkholdheria & lastly h influenzae,pneumococcus.
selection of antimicrobial tailored to local prevelance of pathogens & antimicrobial patterns of resistance.
DYNAMICS OF CHANGE OF ORAL FLORA
1) Healthy subjects → pneumococcus,N menin., strepto pyogenes2) acute/chronic
co→pneumococc,H.influen,enterobac. morbidities MSSA3) 2 + antibiotics for→ESBL+
enterobac.,pseudomonos 3-5 days MRSA4) 3 + antibiotics for→3 + non fermenting MDR
GNB 7 days
(peudomonos,stenotropho., acineto,candida)
Choice of empiric anti microbials
ATS/IDSA recommendations t/t based on timing of onset & risk
factors for MDR pathogens
Risk Factors for Multidrug-Resistant Pathogens Antimicrobial therapy in preceding 90 days Current hospitalization of at least 5 days High frequency of antibiotic resistance in the
community or in the specific hospital unit.
Presence of risk factors for HCAP:
—Hospitalization for at least 2 days in the preceding 90 days
—Residence in a nursing home or extended care facility—Home infusion therapy (including antibiotics)—Chronic dialysis within 30 days—Home wound care—Family member with infection involving MDR pathogen—Immunosuppressive disease and/or therapy
Initial Intravenous Adult doses of Antibiotics
Niederman M. et al, AJRCCM, 2005 Antibiotics Dosage*
Antipseudomonal cephalosporinCefepime 1-2g every 8-12hCeftazidime 2g every 8h Carbapenems Imipenem 500mg every 6h or 1g every 8hMeropenem 1g every 8h ß-Lactam/ ß-lactamase inhibitorPiperacillin-tazobactam 4.5g every 6h AminoglycosidesGentamicin 5-7mg/kg per dTobramycin 7mg/kg per dAmikacin 20mg/kg per d Antipseudomonal quinolonesLevofloxacin 750mg every dCiprofloxacin 400mg every 8h Vancomycin 15mg/kg every 12hs Linezolid 600mg every 12h
NOTE : for legionella → azithro + cipro/levoflox
- For resistant acineto → carbapenem or colistin +
tigecycline - Nebulised colistin/tobramycin are used
as adjunct to systemic antibiotics in severe gram – pneumonia,or,resistant bug eliminated only by high level local drug conc.
- DURATION OF T/T :- - majority of infections can be treated by
8 days course,for non fermenting gram( – ) 14 days
- prolonged t/t is required in : - legionella infection - biofilms/prosthetic devices
- Tissue necrosis,abscess,empyema- persistence of original
infection(perforation, endocarditis)FAVOURABLE CLINICAL COURSE :- - defervescence - improved PaO2/FiO2 - ↓ CRP in 3-5 days - third day CPIS < 6
PREVENTIVE APPROACHES TO VAP
- have focussed on ↓ cross transmission,pulm.
aspiration across ETT cuff, ↓ bacterial load in oropharynx.
HIGHLY EFFECTIVE INTERVENTIONS : 1. SEMIRECUMBENT POSITION 2. SEDATION VACATION 3. DAILY ORAL CLEANSING WITH 2% CHLORHEXIDINE 4. SUBGLOTTIC SECRETION DRAINAGE
FERRER M (clinical infectious d/e 2010) :
- first study that validates 2005 ATS/IDSA guidelines
- the study demonstrated worse microbial prediction of 2005 guidelines,in comparison to previous guidelines,in pts considerd at low risk
for acquiring MDR pathogens & similar low prediction for fungi.
Rather than focusing on VAP, the new surveillance definition
algorithm for adults broadens the surveillance spectrum to
ventilator associated events(VAE) A ventilator-associated
condition (VAC) is identified if, after a 2-day
period of stability or improvement on the
ventilator, the patient develops worsening oxygenation
(specific increases in levels of FIO2 or PEEP
over two or more calender years)
Infection –related ventilator-associated complication (IVAC) is identified in pts with
VAC who meet 2 additional criteria of clinical signs of infection (specifically, defined values for an abnormal temperature or white
count) and antibiotics prescribed for atleast 4 days. Identification of possible & probable VAP within IVAC patients is determined by purulent respiratory secretions and/or specific laboratory and diagnostic tests. The
new algorithm remains complex and the CDC is developing additional guidance for its implementation
Several features of the new VAE definition are important. First, chest radiographs, a
required component in the current definition of VAP,
are no longer used in the definitions of VAEs (including VAP).Second patients who
are receiving rescue ventilation are excluded. Third patients must have a period of at least 2 days of stability or improvent on
mechanical ventilation prior to worsening.fourth,
VAC (and by extension, IVAC and VAP) is limited to patients who have have
been mechanically ventilated for atleast 3 calendar days
The VAP Surveillance Definition Working Group
recommended removing chest radiography from
the surveillance definition entirely. The CDC NHSN definition of VAP (and nowVAE, VAC, and IVAC) was developed to enablesurveillance of an important event; the CDC
specifically states that it should not be used for clinical diagnosis.
AMERICAN JOURNAL OF CRITICAL CARE, September 2012, Volume 21, No. 5
VENTILATOR ASSOCIATED CONDITIONS :- pt on mechanical ventilation > 2 days ↓ baseline period of stability or
improvement,followed by sustained period of worsening
oxygenation ↓ VENTILATOR ASSOCIATED CONDITION(VAC) ↓ general objective evidence of
inflammation/infection ↓ INFECTION RELATED VENTILATOR ASSOCIATED COMPLICATION (IVAC) ↓
positive results of microbiological/laboratory testing
↓
possible or probable VAP
April 2013 CDC/NHSN Protocol
