Ventilator-Associated Pneumonia	11
Rajesh Pande

A 50-year-old diabetic male patient was admitted to the hospital with ischemic stroke (GCS = E1V1M3). He was put on invasive positive-pressure ventilation support. On the fourth day of ICU stay, he developed fever (38.6°C), a rise in total leukocyte count (15.6, N 93%), and heterogeneous, ill-defined shadows in the right lower zone in the chest X-ray. Chest auscultation revealed bronchial breathing in the right infra-axillary area, and the nurse reported an increase in amount and purulence of secretions requiring frequent suctioning. The patient needed 5 mcg/min noradrenaline to maintain systolic blood pressure of more than 100 mmHg.

When a patient on ventilatory support develops new infiltrate in the chest X-ray along with fever and leukocytosis after 48 h of intubation, it is suggestive of venti- lator-associated pneumonia (VAP). This occurs in 9–27% of intubated patients. The risk increases with the duration of mechanical ventilation.

Step 1: Initiate resuscitation

The patient should be resuscitated, as mentioned in Chap. 78.

Step 2: Rule out noninfectious cause of chest infiltrate

There are various noninfectious conditions that can result in pulmonary shadows, which must be ruled out:

•Atelectasis: It is common in postoperative period following upper abdominal surgery due to hypoventilation. Left lower lobe atelectasis is very common following coronary artery bypass grafting. Radiological signs include displaced

R. Pande, M.D., P.D.C.C. (*)

Critical Care & Emergency Medicine, BL Kapur Memorial Hospital, New Delhi, India

e-mail: [e-mail]

R. Chawla and S. Todi (eds.), ICU Protocols: A stepwise approach,	85
DOI 10.1007/978-81-322-0535-7_11, © Springer India 2012

86			R. Pande
Table 11.1 The modified CPIS
CPIS points	0	1	2
Tracheal secretions	Rare	Abundant	Abundant + purulent
Chest X-ray infiltrates	No infiltrate	Diffused	Localized
Temperature (°C)	≥36.5 and ≤38.4	≥38.5 and ≤38.9	≥39 or ≤36
Leukocytes count	≥4,000 and ≤11,000	<4,000 or>11,000	<4,000 or >11,000+ band
(per mm3)			forms ≥500
PaO2/FIO2 (mm Hg)	>240 or ARDS		≤240 and no evidence
			of ARDS
Microbiology	Negative		Positive

fissures; crowded bronchovascular markings and shifts in the positions of the hila, diaphragm, and mediastinum; and increased density or radiopacity of the lung tissue. Fever and leukocytosis may not always be present.

•Aspiration: Right lower lobe is commonly involved. Infiltrates may take up to 12 hrs to appear in the chest x-ray after the event. History of vomiting or bilecolored endotracheal secretions on suctioning is a good clue to the diagnosis. It may be a purely chemical pneumonitis initially, caused by acidic gastric contents.

•Pulmonary embolism: It is generally acute onset in the background of risk factors for deep venous thrombosis and pulmonary embolism (PE).

•Pulmonary hemorrhage may resemble dense alveolar consolidation. Generally, endotracheal (ET) secretions are bloodstained. Coagulation profiles or other immunological markers may be deranged.

•Cardiogenic pulmonary edema.

•Acute respiratory distress syndrome (ARDS).

•Fluid overload.

•Drug reactions.

•Cryptogenic organizing pneumonia.

Scoring systems such as the clinical pulmonary infection score (CPIS) (Table 11.1)

or National Nosocomial Infections Surveillance (NNIS) and biomarkers are a great help in differentiating the pulmonary infiltrate as VAP or noninfectious.

The modified CPIS at baseline is calculated from the first five variables. For positive Gram stain and culture, two points are added to the CPIS baseline score. A score of more than six at baseline or after incorporating the Gram stain or culture result is considered suggestive of pneumonia.

Step 3: Send cultures and initiate empiric antibiotics

•While initial resuscitation is going on, the cornerstone of therapy in suspected infection is prompt and empiric antibiotic therapy.

•Ideally, one should send blood and endotracheal aspirate or do fiberoptic bronchoscopy with bronchoalveolar lavage for Gram stain and quantitative aerobic culture prior to starting antibiotics.

•If there is delay in obtaining samples for logistic reasons beyond an hour, antibiotics should be given without delay.

11 Ventilator-Associated Pneumonia	87
Table 11.2 Microoragnisms causing early and late VAP
Early-onset VAP	Late-onset VAP
Within 4 days of ventilation	³5 days
Pathogens: S. aureus (usually methicillin-sensitive	MDR pathogens: MRSA, Pseudomonas
S. aureus (MSSA)), Streptococcus pneumoniae,	aeruginosa, Acinetobacter baumannii,
Haemophilus influenza, and Gram-negative enteric	and Stenotrophomonas maltophilia
bacilli
Risk of MDR pathogens similar to late onset if	Mortality 33–50%
previous hospitalization or exposure to antibiotics is
present

•The initial choice of antibiotics is of utmost importance. An inappropriate initial choice increases mortality.

1. Selection of empiric antibiotic therapy should be based on the following:

(a)Patient risk factors

(b)Earlyor late-onset pneumonia (Table 11.2)

(c)Recent exposure to specific antibiotic classes

(d)Local epidemiology of infection and antibiogram

(e)Previous antibiotic therapy

2. Detailed history should be taken to identify patients who are at high risk of drug-resistant infection as mentioned below:

•Antimicrobial therapy in preceding 90 days

•Current hospitalization of 5 days or more

•High frequency of antibiotic resistance in the community or in the specific hospital unit

•Presence of risk factors for health care-associated pneumonia (HCAP)

•Hospitalization for 2 days or more in 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 multidrug-resistant pathogen

–Immunosuppressive disease and/or therapy

3.Principles of choosing an antibiotic:

•Cover common organisms responsible for pneumonia depending on the epidemiology of infection and their sensitivity in your ICU.

•Cover resistant organisms like ESBL in patients at risk.

•Avoid the antibiotic class to which the patient has been recently exposed.

•Use parenteral antibiotics.

•Use antibiotics in adequate dose and frequency (see Chap. 49).

4.Follow the antibiotic policy of your unit/hospital.

A. Limited-spectrum antibiotic therapy is appropriate in patients with suspected VAP with no risk factors for multidrug-resistant (MDR) pathogens (early-onset pneumonia).

88	R. Pande

•Recommended antibiotics for early-onset pneumonia as per the guidelines are ceftriaxone or fluoroquinolone, or ampicillin/sulbactam or ertapenem.

B.Late-onset VAP (Table 11.2)

•Gram-negative bacteria (GNB) including ESBL-producing Klebsiella,

Escherichia coli, MDR Acinetobacter, MDR Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus (MRSA), and rarely Enterococcus (vancomycin-resistant enterococci) are the common organisms causing late-onset pneumonia.

•These ESBL bugs are resistant to the thirdand fourth-generation cephalosporins and show an inoculum effect to beta-lactam/beta-lacta- mase inhibitor (BL/BLI) combinations.

•The suggested recommendation is to use carbapenems as empirical therapy in late-onset VAP. In less critically ill patients, BL/BLI combinations may be used.

•For Pseudomonas infections, two antipseudomonal agents should be used. The treatment should be started on the basis of local epidemiology of the ICU. Many of the Pseudomonas species are MDR and are sensitive only to colistin or polymyxin B (use adequate dosage).

•Vancomycin is the preferred choice for Gram-positive organisms (MRSA). Teicoplanin or Linezolid can also be used.

•MDR Acinetobacter strains are currently sensitive only to colistin, high doses of sulbactam, and tigecycline.

Step 4: Send further investigations

While initial resuscitation and empirical antibiotics are being given, basic diagnostic workup should be sent. These should include the following:

•Complete blood count

•CRP, urea, creatinine

•Liver function test

•Prothrombin time, Na, K

•Blood culture—two sets if not sent earlier

•Endotracheal aspirates or fiberbronchoscopy with protected specimen brush (PSB) or bronchoalveolar lavage (BAL)

•Arterial blood gas, lactate

•Procalcitonin

•Urine for microscopy

•Chest X-ray

•ECG or echocardiogram optional if the patient is in septic shock

Step 5: De-escalate antibiotics

•Clinical improvement usually takes 2–3 days, and therapy should not be changed during this time unless the condition deteriorates.

•If protected specimen brush (PSB) or bronchoalveolar lavage (BAL) culture results are negative in a patient who is clinically improving and hemodynamically

11 Ventilator-Associated Pneumonia	89

stable, antibiotic therapy should be discontinued or given for a short duration (5 days).

•If the culture is negative for MRSA, linezolid or vancomycin can be safely stopped, and if the culture is positive for MRSA, other antibiotics can be stopped.

•If no organism is found, one should try to look for other causes of lung shadows, that is, atelectasis, collapse, aspiration, pulmonary embolism, and hemorrhage. It decreases unnecessary exposure to antibiotics and helps to reduce resistance to antibiotics.

•Change to oral therapy once the patient accepts orally and is hemodynamically stable.

•The initial antibiotics should be given intravenously with changeover to oral therapy in responsive patients with an intact gastrointestinal function. The organism should be sensitive to oral antibiotics.

•Fluoroquinolones and linezolid are equally bioavailable in either intravenous or oral preparations.

•All patients with VAP (except the patients with VAP due to non-fermenting Gram-negative bacilli) should receive antibiotics for not more than 8 days.

•Patients with VAP due to P. aeruginosa or Acinetobacter species may be given a 2-week therapy to prevent the risk of recurrence.

•Antibiotic dosing should be adjusted in patients with impaired renal or hepatic function (Fig. 11.1).

Step 6: Prevention of VAP in the ICU

Evidence-based guidelines have recommended a number of measures that may affect the development of VAP (labeled as VAP bundles)

Pharmacological methods	Non-pharmacological methods
1. Hand hygiene with alcohol based	1.	Use of noninvasive mask ventilation
solution
2. Oral care with chlorhexidine	2.	Avoid reintubation
3. Short course of antibiotic therapy (when	3.	Orotracheal and orogastric intubation
clinically applicable)
4. Sedation control and weaning protocol	4.	Use of heat moisture exchanger
5. Restricted blood transfusion	5.	Closed endotracheal suction
6. Vaccines (influenza and pneumococcal)	6.	Subglottic secretion drainage
	7.	Change of ventilator circuit only for each new
		patient
	8.	Semirecumbent positioning
	9.	Shortening duration of mechanical ventilation
	10.	Rotational beds
	11.	Adequate intensive care staffing
	12.	Use of protocol bundles
	13.	Education and training