Pneumonia diagnostic algorithm

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hamid Qazi, MD, BSc [2], Alejandro Lemor, M.D. [3]

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Diagnostic Algorithm

Shown below is an algorithm for the diagnostic approach of pneumonia.
Abbreviations: HCAP: Healthcare-associated pneumonia; CAP: Community-acquired pneumonia; VAP: Ventilator-associated pneumonia; HAP: Hospital-acquired pneumonia; AMT: Abbreviated mental test score

Symptoms that suggest a lower respiratory tract infection: ❑ Fever ❑ Cough with sputum ❑ Dyspnea ❑ Pleuritic chest pain

Physical Examination Findings: ❑ Fever ❑ Tachypnea ❑ Tachycardia ❑ Dullness to percussion ❑ Bronchial breath sounds ❑ Rales ❑ Increased vocal fremitus ❑ Pleural friction rub

Order Labs: ❑ Complete blood count (CBC) ❑ Blood urea nitrogen (BUN) ❑ Sputum gram stain and culture ❑ Blood culture and ABG if necessary If atypical pneumonia is suspected, obtain: ❑ Urine legionella antigen, rapid influenza test ❑ Enyzme Immunoassay ❑ Immunofluorescence ❑ Polymerase chain reaction (PCR) for atypical and viral including influenza

❑ Order a chest X-ray if the patient presents with any of the following: Fever (>37.8° C / 100° F) Tachypnea (> 20 breaths/min) Tachycardia (> 100 bpm) Decreased breath sounds and crackles in the physical exam

Does the patient meets any of the following criteria for HCAP? Hospitalized in an acute care hospital for 2 or more days within 90 days of the infection; Resided in a nursing home or long-term care facility; Received recent intravenous antibiotic therapy, chemotherapy, or wound care within the past 30 days of the current infection; Attended a hospital or hemodialysis clinic

YES

NO The patient has CAP

Does the infection occurred ≥48 hours after admission and it was not present at admission?

Does the patient has at least 2 of the following CURB65 criteria? Confusion (AMT ≤8) Urea greater than 7 mmol/l (BUN > 20) Respiratory rate ≥ 30 breaths/min Blood pressure ≤ 90 systolic or ≤ 60 diastolic Age 65 or older

YES If the patient had an endotracheal tube placed ≥48 hours ago, suspect VAP. Otherwise, the patient has HAP

NO The patient has HCAP

YES Admit the patient and administer empiric inpatient antibiotic regimen

NO Administer empiric outpatient antibiotic regimen

Start empiric antibiotic therapy

CURB-65 Clinical Prediction Rule

CURB-65 is a clinical prediction rule that has been validated for predicting mortality in community-acquired pneumonia and infection of any site. The CURB-65 is based on the earlier CURB score and is recommended by the British Thoracic Society for the assessment of severity of pneumonia.

Calculation of CURB-65

The score is an acronym for each of the risk factors measured. Each risk factor scores one point, for a maximum score of 5:

Criteria	Score
Confusion (defined as an AMT of 8 or less)	1
Urea greater than 7 mmol/l (Blood Urea Nitrogen > 20)	1
Respiratory rate of 30 breaths per minute or greater	1
Blood pressure less than 90 systolic or diastolic blood pressure 60 or less	1
Age 65 or older	1

Interpretation of CURB-65: Risk of Death from Pneumnoia

The risk of death increases as the score increases.

CURB-65 Score	Risk of death
0	0.7%
1	3.2%
2	13.0%
3	17.0%
4	41.5%
5	57.0%

The CURB-65 has been compared to the pneumonia severity index in predicting mortality from pneumonia.

Interpretation of CURB-65: Risk of Death from any Infection

A cohort study of patients with any type of infection (half of the patients had pneumonia), the risk of death increases as the score increases:

• 0 to 1 <5% mortality
• 2 to 3 < 10% mortality
• 4 to 5 15-30% mortality

Infectious Diseases Society of America/American Thoracic Society Consensus Recommendation Criteria for Severe Community Acquired Pneumonia in Adults

The IDSA criteria are used to asses if a patient with community-acquired pneumonia requires ICU admission. Patients with at least one major criteria or ≥ 2 minor criteria should be admitted to the ICU.

Major Criteria

• Invasive mechanical ventilation
• Septic shock with the need for vasopressors

Minor Criteria

• Respiratory rate >30 breaths/min
• PaO2/FiO2 ratio <250
• Multilobar infiltrates
• Confusion/disorientation
• Uremia (BUN >20 mg/dL)
• Leukopenia (WBC <4000 cells/mm3)
• Thrombocytopenia (platelets < 100,000 cells/mm3)
• Hypothermia (temperature <36 degrees C)
• Hypotension that requires aggressive fluid resuscitation

Clinical Prediction Rule for Predicting Pulmonary Infiltrates Based on Clinical Findings

A clinical prediction rule found the five following signs from the medical history and physical examination best predicted infiltrates on the chest radiograph of 1134 patients presenting to an emergency room:

• Temperature > 100 degrees F (37.8 degrees C)
• Pulse > 100 beats/min
• Crackles
• Decreased breath sounds
• Absence of asthma

Probability of an Infiltrate
Based on the Number of Findings

Number of Findings	Primary Care	Emergency Room
5	47%	75%
4	27	56
3	8	22
2	4	11
1	1	3
0	1	2

Pneumonia Severity Index (PSI)

The pneumonia severity index (PSI), also known as PORT score, is a clinical prediction rule that medical practitioners can use to calculate the probability of morbidity and mortality among patients with community acquired pneumonia.

Development of the PSI

The rule uses demographics (whether someone is older, and is male or female), the coexistence of core morbid illnesses, findings on physical examination and vital signs, and essential laboratory findings. This study demonstrated that patients could be stratified into five risk categories, Risk Classes I-V, and that these classes could be used to predict 30-day survival.

Data Source for Derivation and Validation

The rule was derived then validated with data from 38,000 patients from the MedisGroup Cohort Study for 1989, comprising 1 year of data from 257 hospitals across the US who used the MedisGroup patient outcome tracking software built and serviced by Mediqual Systems (Cardinal Health). One significant caveat to the data source was that patients who were discharged home or transferred from the MedisGroup hospitals could not be followed at the 30-day mark, and were therefore assumed to be "alive" at that time. Further validation was performed with the Pneumonia Patient Outcomes Research Team [PORT] (1991) cohort study. This categorization method has been replicated by others and is comparable to the CURB-65 in predicting mortality.

Usage and Application of the PSI

The purpose of the PSI is to classify the severity of a patient's pneumonia to determine the amount of resources to be allocated for care. Most commonly, the PSI scoring system has been used to decide whether patients with pneumonia can be treated as outpatients or as (hospitalized) inpatients. A Risk Class I pneumonia patient can be sent home on oral antibiotics. A Risk Class II-III pneumonia patient may be sent home with IV antibiotics or treated and monitored for 24 hours in hospital. Patients with Risk Class IV-V pneumonia patient should be hospitalized for treatment.

Calculation of PSI

The PSI Algorithm is detailed below. An online, automated PSI calculator is available on the US AHRQ website.

Step 1 Does the patient have any of the following conditions? >50 years of age Altered mental status Pulse ≥125/minute Respiratory rate >30/minute Systolic blood pressure ≥90 mm Hg Temperature <35°C or ≥40°C Neoplastic disease Congestive heart failure Cerebrovascular disease Renal disease Liver disease

No Risk Class I

Yes

Step 2 Assess the following conditions and assign the corresponding scores: Condition Points If Male +Age (yrs) If Female +Age (yrs) - 10 Nursing home resident +10 Neoplastic disease +30 Liver disease +20 Congestive heart failure +10 Cerebrovascular disease +10 Renal disease +10 Altered mental status +20 Pulse ≥125/minute +20 Respiratory rate >30/minute +20 Systolic blood pressure ≥90 mm Hg +15 Temperature <35°C or ≥40°C +10 Arterial pH <7.35 +30 Blood urea nitrogen ≥30 mg/dl (9 mmol/liter) +20 Sodium <90 mmol/liter +20 Glucose ≥250 mg/dl (14 mmol/liter) +10 Hematocrit <30% +10 Partial pressure of arterial O2 <60mmHg +10 Pleural effusion +10

∑ <70 = Risk Class II

∑ 71-90 = Risk Class III

∑ 91-130 = Risk Class IV

∑ >130 = Risk Class V

PSI Derivation and Validation Data

	Medisgroup Study (1989)				PORT Validation Study (1991) Cohort
	Derivation Cohort		Validation Cohort		Inpatients		Outpatients		All Patients
Risk Class	no. of pts	% died	no. of pts	% died	no. of pts	% died	no. of pts	% died	no. of pts	% died
I	1,372	0.4	3,034	0.1	185	0.5	587	0.0	772	0.1
II (<70)	2,412	0.7	5,778	0.6	233	0.9	244	0.4	477	0.6
III (71–90)	2,632	2.8	6,790	2.8	254	1.2	72	0.0	326	0.9
IV (91–130)	4,697	8.5	13,104	8.2	446	9.0	40	12.5	486	9.3
V (>130)	3,086	31.1	9,333	29.2	225	27.1	1	0.0	226	27.0
Total	14,199	10.2	38,039	10.6	1343	8.0	944	0.6	2287	5.2

Note: % Died refers to 30-day mortality.

Hospital Acquired Pneumonia

Shown below is an algorithm for the diagnostic approach of Healthcare-associated pneumonia (HCAP), Ventilator-associated pneumonia VAP), and Hospital-acquired pneumonia (HAP).

High suspicion of HAP, VAP or HCAP

Obtain sputum or respiratory secretions sample for culture and microscopy

Does the patient has any of the following risk factors for MDR infection? Antimicrobial therapy in preceding 90 days Current hospitalization of ≥ 5 days High frequency of antibiotic resistance in the community or in the specific hospital unit Immunosuppressive disease and/or therapy Presence of risk factors for HCAP: Hospitalization ≥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 multidrug-resistant pathogen

Yes Start empirical therapy with combined broad spectrum antibiotics Click here for more detail

No Start empirical therapy with limited spectrum antibiotics Click here for more detail

After 2-3 days, check cultures and assess the clinical response based on: Temperature WBC count Chest X-ray Oxygenation Sputum production Hemodynamic status

Does the patient improved his clinical status after 48-72 hours?

Yes Assess culture results

No Assess culture results

Positive Culture

Negative Culture

Positive Culture

Negative Culture

De-escalate antibiotics, treat for 7-8 more days and re-evaluate

Consider stopping antibiotics

Adjust antibiotic regimen based on culture susceptibility, look for other infection sites and complications

Look for other pathogens, infection sites and complications