fever in the icu: more then just an infection part 1fever in the icu: more then just an infection...

Fever In The ICU: More Then Just An Infection

Part 1Professor Maurice Sinclair, MS, RRT, RPFT, RRT-NPS, RRT-ACCS

Long Island University/Brooklyn Campus

Division of Respiratory

Legal Disclaimer

• Throughout this presentation, there may be images or specific manufacturer technologies. These images are used only as an example of the technology being discussed and in no way are a endorsement by either employees of FOCUS Conferences Inc. or the speaker.

Conflict of Interest

• I do not have any affiliations with, special interest, or have conducted business with the following companies that are in the context within this presentation.

Objectives

• Discuss the key factors that may contribute to abnormal temperature regulation within the body.

• Evaluate how to differentiate between the many different ways of developing a fever within the ICU setting.

Temperature Regulation

• In humans, thermoregulation plays a vital role in homeostasis. The ability to maintain a normal body temp (98.6 degrees Fahrenheit/37 degrees Celsius) despite the changes in environmental temperature is amazing! This control of temperature within the body is mainly performed by the Hypothalamus. This portion of the brain provides a connection between the endocrine system and nervous system to ensure that core body temperature does not vary.


• Natural response to an increase in body temperature

• Hypothalamus sends signals to the sweat glands to secrete sweat onto the surface of our skin. Heat is loss via evaporation during this method.

• Next, hair on the skin lie flat to prevent heat at the skin surface from being trapped due to “still air” in between the hair. These flat hairs increase airflow next to the skin increasing heat loss via convection.

• Also arteriolar vasodilation increases arterial blood flow and capillary blood flow which bring more blood to the skin surface increasing the heat loss by conduction and radiation.

Temperature Regulation• Natural response to a decrease in body temperature

• Hypothalamus sends signals to decrease sweat production, hair that once lied flat raise up (goose bumps) due to minute muscles under the skin attached to the hair follicle. This insulates the skin, preventing heat loss.

• Arteries that once was dilated, now constrict to divert blood flow to the body’s core to warm it. Preventing heat loss by removing warm blood from the skin surface (extreme cold conditions may cause pale skin and numbness).

• Muscles receive signals to shiver to produce heat reducing heat lost to the environment through convention, also the mitochondria can metabolize brown fat (newborns & animals that hibernate) to produce heat energy increasing the temperature of all cells in the body.


• Body heat is generated mostly in deep organs (liver, brain, heart) and skeletal muscles. Heat loss can occur four different ways: Conduction, Convection, Radiation, and Evaporation

• Ex. If skin temperature is greater than that of the surrounding temperature, the body can lose heat via conduction and radiation (and vice versa). During activities such as exercise or sports, evaporation is the main source of heat loss.


• Question: Which is a more effective mechanism to increase body temperature? Shivering or Exercise? Why?

Hyperthermia vs. Fever

Hyperthermia

• A condition where an individual’s body temperature is elevated beyond normal due to failed thermoregulation.

• The individual produces or absorbs more heat than it dissipates.

• The body’s temperature set point remains unchanged unlike with fever.

• Defined as a temperature > 37.5 to 38.3 degrees Celsius (99.5 to 100.9 degrees Fahrenheit)

Causes of Hyperthermia

• Exertional

• Situational (precipitated by medications that reduce vasodilating and sweating mechanisms)

• Drugs (increase internal heat production)

• PPE

Effects of Hyperthermia

• Increase HR and RR

• Headaches, nausea, and vomiting

• Decreased BP

• Dry skin due to the inability to cool the body through perspiration

• Confused, dizziness, delirium

• Organ failure, unconsciousness, and death


• Factors that can hinder the body’s natural mechanism to regulate an increase body temperature

ClothingPlasticHigh vapor pressuresHot, humid environmentsTropical environmentsDeep mines (highly saturated areas)

Fever in the ICU

Fever

• A body temperature > 38.3 degrees Celsius (101 F) represents a fever, while a lower threshold of 38.0 degrees Celsius (100.4 F) can be used for immunocompromised patients with neutropenia.

• Most accurate measure of core body temperature can be measured by thermistor-equipped catheters (continuous temperature monitoring) in the pulmonary artery, esophagus, or urinary bladder.

• Less accurate measurements are rectal, oral, and tympanic.• Axillary and temporal artery sites are not recommended for temperature

measurements.

Fever

• Fever is the result of inflammatory cytokines (endogenous pyrogens) that act on the hypothalamus to elevate the set body temperature. Any condition that triggers a systemic inflammatory response will produce a fever!

• First, a fever is a sign of inflammation not infection. Severity of a fever does not correlate with the presence or severity of infection. High fevers can be caused by drugs and life-threatening infections are sometimes absent fevers. 50% of ICU patients who develop a fever have no apparent infection.

Fever

• Understanding the distinction between inflammation and infection is important to evaluate the cause of the fever, but for also stopping the response to treat fevers with antibiotics.

Fever

• Remember, a fever is not a result of abnormal temperature regulation but involves an intact thermoregulatory system operating at a higher set point.

• Fever enhances immune function by increasing the production of antibodies and cytokines, activating T-lymphocytes, and enhances phagocytosis by neutrophils and macrophages.

• Increased body temperature suppresses bacterial growth and viral replication.

• Fever is normal adaptive response that enhances the ability to eradicate infection.

Fever

• Initial response includes peripheral vasodilation (to loss heat via), increased metabolism, increased oxygen consumption, decreased cerebral blood flow, increase cardiovascular and pulmonary demand.

Noninfectious sources of a fever in the ICU

Noninfectious sources of a fever in the ICU• Early post-op fever- tissue injury sustained during the surgical procedure,

usually resolves in 24 to 48 hours (15% to 40% of patients develop fever during the first week after major surgery)

Atelectasis Does Not Produce A Fever

• Yes, there is a high incidence of patients who develop atelectasis and also may develop a fever.

• Studies were performed and no correlation was shown between lobar atelectasis and fever.


• Venous Thromboembolism- acute pulmonary embolism can produce a fever lasting up to 1 week


• Blood Transfusions- appears during or up to 6 hours after transfusion (platelet transfusion (1 per 14) is more prevalent then packed RBCs (1 per 200)


• Drug Fever- suspicion of drug fever usually occurs when there are no other likely source of fever

• Poorly understood

• Fever can vary from a few hours to more than 3 weeks after the onset of drug therapy

• If suspected, discontinue the drug right away!

Fever

• Drug-Associated Fever in the ICUCommon Offenders Occasional Offenders Clinical Findings

Amphotericin Cimetidine Rigors

Cephalosporins Carbamazepine Myalgias

Penicillins Hydralazine Leukocytosis

Phenytoin Rifampin Eosinophilia

Procainamide Streptokinase Rash

Quinidine Vancomycin Hypotension


• Iatrogenic Fever- faulty thermal regulators in water mattresses, aerosol generators, humidifiers

Nosocomial Infections that may cause a fever in the ICU

Nosocomial Infectionsthat can cause a fever in the ICU

• VAP (Ventilator-Associated Pneumonia)


• Urinary tract infections, catheter-related infections or recent exposure to broad spectrum antibiotics (Candida species),


• Surgical site infections (Staph epidermidis in open heart surgery, gram-negative aerobic bacilli and anaerobes in bowel surgery), appears 5 to 7 days after

• Tx. includes drainage, debridement, and antibiotics


• Necrotizing wound infections (Clostridium species or B-hemolytic streptococci),


• C-Diff


• Sinusitis (caused by nasogastric tubes or endotracheal tubes that can block the ostia draining the paranasal sinuses)

• CT scan is used for detection


• Meningitis in neurosurgery patients


• Endocarditis in patients with damaged or prosthetic heart valve


• Abdominal abscesses in patients who have had major abdominal surgery.

How To Determine The Cause of a Fever


• Blood cultures for all ICU fever cases where a noninfectious source is unlikely.


• Procalcitonin (PCT)- a marker for sepsis and detecting infection in febrile patients, PCT levels above normal >0.5 ng/ml suggest infection.

Markers of Infection in Febrile ICU Patients

Marker PPV (positive predictive ratio)

NPV (negative predictive ratio)

PLR (positive likelihood ratio)

WBC > 12000/mm3 76% 62% 2.7

CRP > 100 mg/dl 62% 54% 1.4

PCT > 0.5 ng/dl 75% 68% 2.6

PCT > 1.0 ng/dl 90% 72% 8.1


• Empiric Antimicrobial Therapy- recommended for all ICU patients with a fever, unless high likelihood of a noninfectious source. Prompt initiation of therapy is considered essential, especially in patients with neutropenia, <500.

• When fever persist for longer then 3 days even after the start of antibiotics, consider an antifungal agent.

Common Isolates In ICU Patients

Gram-Positive (55%) Gram-Negative (50%)

Staph aureus (27%) Escherichia coli (14%)

MRSA (18%) Pseudomonas spp (13%)

Staph epidermidis (9%) Klebsiella spp (9%)

Presenter

Presentation Notes

Data from 607 ICUs in North America

Treatment for Fever in The ICU


• Antipyretic Drugs or Prostaglandin E inhibitors (prostaglandin E mediates the febrile response to endogenous pyrogens) includes aspirin, acetaminophen, and nonsteroidal anti-inflammatory agents (NSAIDs).

• Acetaminophen is the leading cause of acute liver failure in the USA (do not use with patient that have hepatic problems)

• NSAIDs such as Ibuprofen or Ketorolac is normally used


• External cooling has been used for short term fever suppression (48 hours) and for its ability to provide more continuous temperature control (less risk of adverse effects from antipyretic drugs)

References

• Commichau C, Scarmeas N, Mayer SA. Risk factors for fever in the ICU. Neurology 2003; 60:837-841

• Peres Bolta D, Lopes Ferriera F, Melot C, et al. Body temperature alterations in the critically ill. Intensive Care Med 2004; 30:811-816.

• Freischlag J, Busuttil RW. The value of postoperative fever evaluation. Surgery 1983; 94:358-363

• Vincent j-l, Rello J, Marshall J, et al. International study of the prevalence and outcomes of infection in intensive care units. JAMA 2009; 302:2323-2329

References

• Kluger MJ, Kozak W, Conn CA, et al. The adaptive value of fever. Infect Dis Clin North Am 1996; 10:1-20

• Schmitt BD. Fever phobia: misconceptions of parents about fevers. Am J Dis Child 1980; 134:176-181

• Saper CB, Breder CB. The neurologic basis of fever. N Engl J Med 1994; 330:1880-1886

• Cunch B. Drug fever: The importance of recognition. Post grad Med 1986; 80:123-129

References

• Plaisance KI, Mackowiak PA. Antipyretic therapy. Physiologic rationale, diagnostic implications, and clinical consequences. Arch Intern Med 2000; 160:449-456

• Van Oss CJ, Absolom DR, Moore LL, et al. Effect of temperature on the chemotaxis, phagocytic engulfment, digestion, and oxygen consumption of human polymorphonuclear leukocytes. J Reticuloendothel Soc 1980; 27:5610565

• Engoren M. Lack of association between atelectasis and fever. Chest 1995; 107:81-84

• Shelds RT. Pathogenesis of Postoperative pulmonary atelectasis: and experimental study. Arch Surg 1949; 48:489-503

References

• Cockerill FR, Wilson JW, Vetter EA, et al. Optimal testing parameters for blood cultures. Clin Infect Dis 2004; 38:1724-1730

• Richards MJ, Edwards JR, Culver DH, Gaynes RP. The National Nosocomial Infections Surveillance System. Nosocomial infections in combined medical-surgical intensive care units in the U.S. Infect Control Hosp Epidemiol 2000; 21:510-515

• Horan TC, Andrus M, Dudeck MA. CDC/NHSN surveillance definition of healthcare-associated infection and criteria for specific types of infections in the acute care setting. Am J Infect Contro 2008; 36:309-332

The End. Any Questions?

fever in the icu: more then just an infection part 1fever in the icu: more then just an infection...

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