fever in icu

FEVER IN ICU

SAMIR EL ANSARY

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9555/ Wellcome in our new group ..... Dr.SAMIR EL ANSARY

Temperature constitutes a

fever

A temperature of 38°C (100.4"F) in infants or

38.3"C (100.9"F) in adults defines a fever.

However, immunocompromised or functionally

immunocompromised patients may not be able

to mount a temperature high enough to

constitute a fever by this definition.

In these patients low-grade temperature

elevations should be addressed cautiously.

Examples of patients in which the clinician

should maintain a high index of suspicion for

masked fever include the elderly, diabetics,

intravenous drug users, chronic alcoholics,

people with HIV / AIDS, people on chronic

steroids or immune-modulating drugs, and

Temperature constitutes a

fever

A temperature of 38°C (100.4"F) in infants or

38.3"C (100.9"F) in adults defines a fever.

However, immunocompromised or functionally

immunocompromised patients may not be able

to mount a temperature high enough to

constitute a fever by this definition.

In these patients low-grade temperature

elevations should be addressed cautiously.

Examples of patients in which the clinician

should maintain a high index of suspicion for

Masked fever include the elderly,

diabetics, intravenous drug users,

chronic alcoholics, people with HIV /

AIDS, people on chronic steroids or

immune-modulating drugs, and

neutropenic patients.

Methods of measuring

temperature equivalent

Rectal temperaturesAre the most accurate representation of core

body temperature and are, therefore,

considered the gold standard.

Oral, axillary, and tympanic temperature

measurements lack sensitivity

And thus a lack of fever when measured by

these methods does not rule out a fever.

Methods of measuring

temperature equivalent

In addition, there is no reliable correction factor

for these alternate modalities.

When an accurate temperature measurement

is crucial to the patient's care

A rectal temperature measurement

is necessary.

How does the body create

fever?

Core body temperature is controlled by

the anterior hypothalamus.

A fever is caused by elevation of the

hypothalamic set point.

The body responds by attempting to

generate heat (e.g., by shivering or by

increasing the basal metabolic rate) to

elevate core temperature.

The difference between a fever

and hyperthermia

In contrast to fever, hyperthermia results in

an elevated temperature without alteration of

the hypothalamic set point.

In cases of hyperthermia, the body attempts

to cool itself to achieve a normal

temperature, primarily by increasing

sweating.

A temperature of 41.5"C

(106.7"F) or greater usually

represents hyperthermia

and not a true fever,

especially in adults.

Some examples of

hyperthermia include

Heat stroke, thyroid storm,

burns, and toxidromes, such as

neuroleptic malignant

syndrome, serotonin syndrome,

and malignant hyperthermia.

How do I address a patient with a

subjective fever at home who is

afebrile in the ED?

This situation is mostly commonly encountered

in pediatrics.

Mothers are accurate in assessing the

presence or absence of a fever 50% to 80% of

the time, and they seem to be more accurate

at detecting when the child is febrile than they

are at determining that the child is afebrile.

Most experts feel that palpable fevers

reported by mothers are probably real

and need to be taken seriously.

Additionally, the practice of attributing

fevers to bundling has been disproved;

bundling does not alter core body

temperatures in infants.

Does the degree of fever indicate

the severity of the illness?

In general, no. There is no degree of fever that

has been clearly associated with a specific risk

of serious infection in patients.

The exception to this may be in nonimmunized

children; prior to the widespread use of the

Haemophilus influenza vaccine, temperatures

over 41.1 "C (105.98"F) were associated with

a higher incidence of serious bacterial illness

in children.

Prior to the approval of the

pneumococcal conjugate vaccine in

2000, occult pneumococcal

bacteremia was observed to be

three times more likely in children with a fever of 39.5"C (103.1°F) or

greater versus a fever of 39.0°C

(102.2"F).

The best way to reduce a fever

Most physicians use antipyretics for patients

who are uncomfortable because of fever.

Within the range of 40°C to 42"C, there is no

evidence that fever is injurious to tissue.

Use of antipyretics should be considered in

pregnant women and patients with preexisting

cardiac compromise who would not tolerate the

increased metabolic demands of a fever.

Acetaminophen is the antipyretic of

choice in most hospitals.

Ibuprofen, other nonsteroidal anti-

inflammatory drugs (NSAIDS), and

aspirin are also effective.

However, due to the association with

Reye's syndrome, aspirin is usually

not recommended for children.

Response to these agents is seen with both

serious and benign causes of fever.

Recurrence of fever after antipyretics wear off is

often concerning for parents

But it does not distinguish between serious and

benign causes of fever, and base our concerns

on the child's behavior rather than the height of

the fever or its response to antipyretics.

Complementary methods, such as

cool bathing and undressing the

patient, are generally not felt to be

effective at significantly lowering core

body temperature and should be

reserved as adjuncts for higher

temperatures.

If the temperature is above

41.5"C (106.7"F)

The diagnosis of hyperthermia

should be considered and rapid

cooling measures used if any

concern about this condition

exists.

Causes of feverFirst and foremost, at the top of the list is

infection (both bacterial and viral).

Infection causes the vast majority of fevers,

but other causes must also be included in the

differential diagnosis:

•Neoplastic diseases

•(e.g., leukemia, lymphoma, or solid tumors)

•Collagen vascular diseases

•(e.g., giant cell arteritis, polyarteritis nodosa,

systemic lupus erythematosus, or rheumatoid

arthritis)

Causes of fever

•Central nervous system lesions(e.g., stroke, intracranial bleed, or trauma)

•Illicit drug use(cocaine, ecstasy [MDMA], or methamphetamines)

•Withdrawal syndromes•(delirium tremens or benzodiazepine withdrawal)

•Factitious fever

•Medications

Medications can cause fevers

Any drug is capable of producing a drug

fever; however, the most common culprits are

penicillin and penicillin analogs .

The fever usually begins 7 to 10 days after

initiation of drug therapy.

There is an associated rash or eosinophilia in

about 20% of cases.

Drug fever should always be a diagnosis

of exclusion.

Key elements

for

Fever diagnosis

Pay particular attention to

associated symptoms

(e.g., cough, dysuria, diarrhea, or

headache), duration of fever, ill

contacts, history or risk of

immunecompromise, and past

medical history, particularly

comorbid illnesses.

In the physical examination,

note the general appearance of

the patient, such as mild mental

status changes or rashes that

might be indicative of more

serious systemic diseases.

In addition to a thorough routine

physical examination, in appropriate

cases a more detailed examination of

the patient should be done to look for

occult sites of infection, such as the

nose/sinuses, rectum (i.e., prostatitis,

perirectal abscess), and pelvic

examination (i.e., pelvic inflammatory

disease, tubo-ovarian abscess).

DRUGS COMMONLY

ASSOCIATED

WITH DRUG FEVERS

Antibiotics

lsoniazid (INH)

Nitrofurantoin

Penicillins, cephalosporins

Rifampin

Sulfonamides

Cardiac drugs

Hydralazine

Methyldopa

Nifedipine

Phenytoin

Procainamide

Quinidine

Nonsteroidal anti-inflammatory drugs

Ibuprofen

Salicylates

Anticancer drugs

Bleomycin

Streptozocin

Anticonvulsants

Phenytoin

Carbamazepine

Others

Barbiturates

Cimetidine

Iodides

Relationship between fever and

tachycardia

The pulse should increase about 10 beats per minute for each 0.6"C (1°F) increase in

temperature.

A pulse-temperature dissociation occurs when

the patient has a fever but a heart rate that is

lower than would be expected for the degree of

fever.

This dissociation occurs in

typhoid, malaria, Legionnaires' disease, and

mycoplasma.

Relationship between fever and

tachycardia

In early septic shock,

tachycardia that is

inappropriate for the degree of

fever is often seen.

Relationship between fever and

tachycardia

Tachypnea out of proportion to fever is

characteristic of

Pneumonia and gram-negative

bacteremia.

Hypotension, particularly paired with

tachycardia

raises the concern of sepsis.

Do all septic patients have a fever?

No, in fact, remember that within the

definition of systemic inflammatory

response syndrome (SIRS) is

temperature greater than 38°C

(104"F) or less than 36°C (96.8"F).

Not all fevers are caused by

infection, and not all infected

patients have a fever.

Should everyone with a fever

get antibiotics?

Absolutely not.

Antibiotic use should be based on the

patient's specific presentation and

diagnosis after an appropriate history

and physical examination and directed

laboratory and ancillary tests.

Most clinicians advocate giving

antibiotics immediately to any patient

who appears toxic or has suspected

bacterial meningitis, without delaying

for results of ancillary test or culture

results.

Other patients who should be

considered for early antibiotics are

Immuneoc-ompromised patients and

elderly patients.

Neutropenic fever

In patients with neutropenia (an

absolute neutrophil count below 1,000

per square mm),

A single temperature above 38.3"C

(100.9"F) is considered a fever, and

fever in these patients is secondary to

infection until proven other-wise.

Neutropenic fever

The risk of severe sepsis and septicemia is

higher in these patients, and this initial

workup should include screening for all

sources of infection.

Initial studies should include, at a minimum, a

cell count

and differential, metabolic panel, blood

cultures, chest radiograph, and urinalysis; All

these patients should receive antibiotics.

Fever of unknown origin (FUO)A fever greater than 38.3"C (100.9"F)

documented on several occasions during a

period longer than 3 weeks, with an uncertain

diagnosis after 1 week of evaluation in the

hospital.

The most common cause of FUO is

occult infection

(particularly tuberculosis) and

malignancyEach accounting for approximately

30% of cases.

For how long do typical

febrile illnesses last?

In most cases, the fever

resolves within 3 to 7 days.

Is a fever a friend or foe?

Although fever per se is self-limiting and rarely

serious, it is often considered by patients and

doctors to be a major and harmful sign of

illness, and parents and medical practitioners

may develop what has been termed fever

phobia, treating the fever almost as an illness

in itself rather than a symptom.

More and more research is proving, however,

that fever may be beneficial in fighting some

infections.

Higher

Tempertures increase the activity of

neutrophils and lymphocytes and decrease

the levels of serum iron, a substrate that many

bacteria need to reproduce.

It enhances immunological

processes, including the activity

of IL-1, T helper cells and

cytolytic T cells, and B cell and

immunoglobulin synthesis.

Alternating acetaminophen and

ibuprofen for fevers. Is this

effective?

This is not an evidence-based practice.

There is presently no scientific evidence that

this combination is safe or achieves faster

antipyresis than an adequate dose of either

agent alone.

The observed fever reduction of 0.5"C when

combining antipyretics,

Compared with a single antipyretic, is

insufficient to warrant routine use.

Additionally, alternating antipyretics can be

confusing for caregivers, potentially leading to

incorrect dosing of either product.

The practice can also increase parents' fever

phobia because it increases parental

preoccupation with the height of the fever.

Global Critical Carehttps://www.facebook.com/groups/1451610115129555/#!/groups/145161011512

9555/ Wellcome in our new group ..... Dr.SAMIR EL ANSARY

GOOD LUCK

SAMIR EL ANSARY

ICU PROFESSOR

AIN SHAMS

CAIRO

elansarysamir@yahoo.com