Severe Pneumonia in the ICU
First Things First (assess & treat for the following)
- Does patient have any respiratory distress that requires immediate attention?
- PaCO2 > 50 mmHg
- pH < 7.2
- PaO2 < 70 mmHg or O2 saturation < 90%
- Does patient have evidence of low BP: systolic < 90 mmHg and/or diastolic < 60 mmHg?
- Does patient have mental status changes?
- Does patient have evidence of renal dysfunction &/or decreased urine output?
- Is the CXR showing bilateral, multilobar or progression of pulmonary infiltrates?
- Is the patient immunocompromised?
- If yes, refer to Infections in Immunocompromised Host. Mgt of infection in immunocompromised hosts is very specific and should mandate early consultation with other specialists.
Definitions
- Community-acquired pneumonia (CAP)
- Severe community-acquired pneumonia (SCAP)
- Nosocomial pneumonia (NP) or hospital-acquired pneumonia (HAP)
- Ventilator-associated pneumonia (VAP)
- Nosocomial pneumonia in a mechanically ventilated patient
- Healthcare-associated pneumonia (HCAP)
- A NP in patients from nursing homes, dialysis centers, etc. who are exposed to multidrug-resistant (MDR) bacteria
- Important to differentiate the different groups of patients who may present with pneumonia in the ICU:
- Patient origin: from the community, immunocompromised host either from the community or a nursing home, or currently in the hospital
- Patient in the hospital and/or ICU who develops a pneumonia, and/or receiving mechanical ventilation, who develops a nosocomial pneumonia
- Demographic characteristics
- Most relevant are age, comorbid conditions, medication use, history of immunosuppression, geographic & travel history, exposure to animals.
- SCAP
- American Thoracic Society (ATS) defines SCAP & need for ICU admission by of at least 2 of the minor criteria parameters (systolic BP 90 mmHg or less, multilobar disease, PaO2/FIO2 < 250 torr) or one of the major criteria (need for mechanical ventilation or septic shock).
- Mortality due to SCAP: 35-40%
- NP (HAP, VAP, HCAP)
- Mortality rate of NP in the ICU is 35-70%.
- Risk factors for NP are grouped into 3 categories:
-
- Underlying acute illness that predisposes to secondary pneumonia
- Acute lung injury
- Abdominal, thoracic or cardiac surgery
- Head injury/coma
- Immunosuppressive illness
- Coexisting medical illness
- Age >60 yo
- Obesity
- Cardiac diseases
- Albumin < 2.2 g/dl
- Burns
- Multiple organ failure
- Chronic pulmonary diseases (chronic obstructive pulmonary disease, asthma, bronchiectasis, etc.)
- Renal failure
- Malignancies
- Diabetes mellitus
- Splenic dysfunction
- Factors associated with therapies frequently used in ICU
- Intubation with mechanical ventilation >2 days: most important, risk factor increases the risk 7- to 21-fold!
- Antibiotic therapy
- Bacteriologically virulent pathogens (Pseudomonas aeruginosa, Acinetobacter spp.)
- Tracheostomy
- Nasogastric tube use
- Transfusion >4 units PRBC
- Use of corticosteroids, immunosuppressants, H2 antagonists
- Prolonged sedation and/or paralysis
- Head of bed elevation < 30 degrees
- Underlying acute illness that predisposes to secondary pneumonia
Etiology
- SCAP
- Patients with severe pneumonia in the ICU may have a pneumonia acquired:
- In the community (SCAP),
- In the hospital (HAP),
- While being mechanically ventilated (VAP) or
- From nursing homes, dialysis centers, etc. who are exposed to MDR bacteria (HCAP)
- Most common cause of CAP is S. pneumoniae. 40% of S. pneumoniae is resistant to penicillin and is called drug-resistant S. pneumoniae.
- S. pneumoniae, H. influenzae, Mycoplasma pneumoniae, influenza A virus, coronavirus (SARS), S. aureus, C. pneumoniae, C. psittaci, L. pneumophila, C. burnetii, gram-negative bacilli (Klebsiella spp, E. coli, Pseudomonas aeruginosa, etc). P. aeruginosa infection is a risk factor in patients with underlying lung diseases, as seen in bronchiectasis, cystic fibrosis & chronic corticosteroid use.
- Opportunistic pathogens: P. carinii, cytomegalovirus, Cryptococcus neoformans, M. tuberculosis, M. avium intracellulare, A. israelii, N. asteroides, Aspergillus spp.
- Rare pathogens: pertussis, typhoid, paratyphoid, brucellosis, leptospirosis, tularemia, anthrax, plague, Q fever
- Viruses: Epstein-Barr virus, cytomegalovirus, measles, varicella, herpes, hantavirus
- Patients with severe pneumonia in the ICU may have a pneumonia acquired:
- NP (HAP, HCAP, VAP)
- In the first 5 days of hospitalization, pneumonia is usually caused by Streptococcus pneumoniae, Haemophilus influenzae, anaerobic bacteria & less frequently Staphylococcus aureus (SA) (including methicillin-resistant SA [MRSA]) & Moraxella catarrhalis.
- >5 days after admission, pneumonia is more commonly caused by hospital-acquired pathogens such as aerobic gram-negative bacilli, SA (often MRSA), Legionella pneumophila. Less frequent: influenza A & B, respiratory syncytial virus, Aspergillus spp., Pneumocystis carinii, Mycobacterium tuberculosis.
- Gram-negative rods: Pseudomonas aeruginosa, Enterobacter spp., Acinetobacter spp., & enteric gram-negative rods (Klebsiella, E. coli, Proteus, Serratia) are the predominant pathogens & are at high risk to be drug-resistant.
- SA (20-30% are MRSA). MRSA is seen in patients with underlying COPD or prior antibiotic use and/or in patients receiving mechanical ventilation.
- Polymicrobial infections (60%) are common in patients on mechanical ventilation. MRSA, S. pneumoniae & H. influenzae are found in early-onset (before day 5) nosocomial pneumonia.
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Last updated: May 5, 2010
Citation
"Severe Pneumonia in the ICU." Pocket ICU Management, PocketMedicine.com, Inc, 2010. Anesthesia Central, anesth.unboundmedicine.com/anesthesia/view/Pocket-ICU-Management/534213/all/Severe_Pneumonia_in_the_ICU.
Severe Pneumonia in the ICU. Pocket ICU Management. PocketMedicine.com, Inc; 2010. https://anesth.unboundmedicine.com/anesthesia/view/Pocket-ICU-Management/534213/all/Severe_Pneumonia_in_the_ICU. Accessed December 1, 2024.
Severe Pneumonia in the ICU. (2010). In Pocket ICU Management. PocketMedicine.com, Inc. https://anesth.unboundmedicine.com/anesthesia/view/Pocket-ICU-Management/534213/all/Severe_Pneumonia_in_the_ICU
Severe Pneumonia in the ICU [Internet]. In: Pocket ICU Management. PocketMedicine.com, Inc; 2010. [cited 2024 December 01]. Available from: https://anesth.unboundmedicine.com/anesthesia/view/Pocket-ICU-Management/534213/all/Severe_Pneumonia_in_the_ICU.
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T1 - Severe Pneumonia in the ICU
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Y1 - 2010/05/05/
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