fever in icu
TRANSCRIPT
FEVER IN ICU
SAMIR EL ANSARY
Global Critical Carehttps://www.facebook.com/groups/1451610115129555/#!/groups/1451610115129555/
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
neutropenic patients.rectal temperature measurement is necessary.
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 COMMONLYASSOCIATEDWITH DRUG FEVERS
Antibioticslsoniazid (INH)NitrofurantoinPenicillins, cephalosporinsRifampinSulfonamidesCardiac drugsHydralazineMethyldopaNifedipinePhenytoinProcainamideQuinidineNonsteroidal anti-inflammatory drugsIbuprofenSalicylates
Anticancer drugsBleomycinStreptozocinAnticonvulsantsPhenytoinCarbamazepineOthersBarbituratesCimetidineIodides
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 intyphoid, 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 countand 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 malignancy
Each 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/1451610115129555/
Wellcome in our new group ..... Dr.SAMIR EL ANSARY
