Infectious Diseases in Critical Care Medicine

System PE ID findings Noninfectious mimics Diagnostic features

Extreme hyper-
pyrexia
(> 1068 F)

1. Gram-negative
   bacteremia (rare)

l Malignant hyperthermia

l Neuroleptic malignant

syndrome

l Central fever including post

craniotomy

l Drug fever

l Heat stroke

l Thyrotoxic crisis

l Cocaine/phencyclidine

Fever of> 1068 F is almost

never due to an infection.

Suppressed TSH with

elevated T 4 ,T 3 in thyro-

toxicosis. Muscle rigidity and

increased CK in NMS.

Sustained fever 1. Gram-negative
pneumonia

l Central fever Blood cultures positive in

bacteremia. There may be

relative bradycardia in

central fever.

Double quotidian
fever

1. Gonococcal endo-
   carditis


2. Mixed malaria
   infection


3. Visceral
   leishmaniasis

l Adult-onset JRA Blood culture and thick

peripheral blood smear. Biopsy

of bone marrow, liver, lymph

node, or spleen for leishmania.

Clinical criteria and elevated

ferritin in JRA

Hypothermia 1. Overwhelming
sepsis

l Exposure/emersion

l Drugs (ethanol,

phenothiazines,

sedative/hypnotics)

l Metabolic (hypothyroidism,

hypoadrenalism,

hypopituitarism, hypoglycemia)

l Acute spinal cord transaction

l Burns/exfoliative dermatitis

l Aggressive fluid resuscitation

Clinical setting. Glucose, TSH,

cortisol level.

Relative
bradycardia

1. Typhoid fever


2. Legionellosis


3. Babesiosis


4. Q fever


5. Dengue fever


6. Rickettsial
   organisms


7. Yellow fever


8. Psittacosis


9. Malaria


10. Leptospirosis


11. Brucellosis


12. Chlamydophila
    pneumoniae
    infection

l Cardiac drugs (i.e., beta

blockers)

l CNS fever

l Drug fever

l Lymphoma

l Factitious fever

l Traumatic hypotension

A pneumonic process and

relative bradycardia suggests

legionellosis, Q fever,

C. pneumoniae, or psittacosis.

Hemolytic anemia suggests

malaria or babesiosis.

Leukopenia suggests typhoid

fever.

Orthopnea 1. Biapical
pneumonia

2. Tuberculous
   pericardial
   restriction/effusion

l Left-sided CHF

l Diffuse interstitial lung disease

l Intrathoracic anterior

mediastinal mass (i.e., goiter,

thymoma, lymphoma, cancer)

l Bilateral diaphragmatic paralysis

l Pulmonary veno-occlusive

disease

Fever, crackles, and signs of

consolidation in the upper

lung fields in pneumonia.

Increased JVP, edema, S 3

gallop in CHF. Kussmaul

sign in pericardial restriction.

Fixed diaphragms on

percussion in diaphragmatic

paralysis. Imaging for

mediastinal masses.

Platypnea 1. Bibasilar
pneumonia

l Cirrhosis

l Bilateral pulmonary emboli

l Severe emphysema

l Bilateral pleural effusions

Fever suggests pneumonia.

Imaging (X Ray, CT) for

other pulmonary disorders.

50 Mishriki