Management of Fever Flashcards
What is fever?
A normal response to various circumstances - usually due to viral or bacterial infection.
A controlled physiologic response where the core temperature of the body temperature is increased and new balance of heat loss and production is established
It’s a defence system; the body’s immune response to pyrogens
What are the 6 methods of taking body temperature?
Rectal Ear Oral Forehead Axillary Transcutaneous
What defines a fever?
Generally defined as rectal temperature over 38ºC
The degree of the child’s fever may correlate the likelihood of a serious bacterial infection
Generally self-limiting (3 days)
A fever is generally accompanied by what?
Mild dehydration, febrile seizures, delirium and discomfort (reassure parents; monitor; and refer to physician if necessary)
What is considered above normal temperature?
Rectal: above 38ºC
Oral: above 37.5ºC
Axillary: above 37.3ºC
Tympanic: above 38ºC
What is the recommended technique for measuring temperature from birth to two years?
- Rectal
- Axillary
Tympanic is not recommended
What is the recommended technique for measuring temperature from 2 to 5 years old?
- Rectal
2. Axillary, tympanic
What is the recommended technique for measuring temperature for children older than 5?
- Oral
2. Axillary, tympanic
What are some practical points for measuring temperature?
Do not use an oral thermometer for rectal purposes and vice versa
A digital thermometer may be used for either oral or rectal (plastic sheaths are available)
Digital is preferred - convenience (safer, faster, easier) and cost (cheaper in the long run)
Fever strips (transcutaneous method) no longer recommended - not an accurate reading
Describe the pathophysiology of a fever
Fever is produced by pyrogens of either endogenous or exogenous origins
Prostaglandins of E2 series are produced in response to the circulating pyrogens and elevate the thermoregulatory set point in the hypothalamus
Within hours, the body temperature increases the new set point and fever occurs
Body temperature is increased by vasoconstriction of peripheral blood vessels, shivering to increase heat production, behavioural changes
What are endogenous pyrogens?
Proteins that induce fever including chemicals such as interleukin-1, tutor necrosis factor alpha, interleukin-6, ciliary neurotropic factor and interferon gamma
What are exogenous pyrogens?
Chemicals produced by bacteria or by components of the organism. Stimulate the release of endogenous pyrogens
What controls the body’s temperature?
Hypothalamus is the body’s thermoregulatory centre - balancing heat production/dissipation
Fever is controlled by the hypothalamus which increases body temperature when exposed to pyrogens (increased production of prostaglandins)
What is hyperthermia?
An increase in body temperature not due to the hypothalamus (i.e., physical exertion)
What are risk factors?
Bacterial infection Viral infection Cancer Multisystem diseases Medications
When should a patient be referred?
Babies under 6 months
Fever lasting over 72 hours (with out without treatment)
Fever lasting over 24 hours without obvious cause
Fever over 40.5ºC
Child appears very ill, is excessively cranky or irritable, cries inconsolably
Patient has persistent wheezing and cough
Patient has rash with fever (could be life threatening)
Patient is difficult to arouse, confused or delirious, has recently received chemotherapy or has serious underlying disease
Patient had recent surgery or dental procedures, recently travelled or eaten raw or poorly cooked meat/fish or recently started a new drug (associated with hypersensitivity)
Child has any other symptoms that bothers the parents
What are signs and symptoms associated with fever
Sweating Headache Malaise and fatigue Backache, myalgia and arthralgia Dehydration Discomfort Febrile seizures
What are the goals of therapy?
Provide patient comfort
Reduce parental anxiety
Reduce metabolic demand caused by fever in patients with cardiovascular or pulmonary disease
Prevent or alleviate fever-associated mental dysfunction
What are non-pharmacological options?
Remove excess clothing, blankets and bedding (keep person cool and comfortable)
Increase fluid intake to replace water loss from fever produced sweating (prevent dehydration)
Avoidance of extreme physical exertion
Maintain normal room temperature
Should a fever be treated pharmacologically?
There are arguments against treating a fever (it’s part of the body’s defence mechanism)
The decision to use antipyretics must be individualized
The main reason to treat a fever is the patient discomfort associated with fever
What is fever phobia?
Unrealistic concerns and misconceptions that can result in heightened anxiety and inappropriate treatment of fever
What do antipyretics do?
Antipyretic agents reduce body temperature in febrile patients via decreasing prostaglandin synthesis by inhibiting the cyclo-oxygenase (COX) enzyme
Can acetaminophen and ibuprofen be used for a fever?
They are the the only therapeutic choices for managing a fever in children
What is the goal of pharmacological treatment of a fever?
Reduction of the hypothalamic set point
Do not lower “normal” body temperature
Regular/short term use of agents is recommended - intermittent use may cause ‘swings’ in temps (increased metabolic demand)
What is the MOA of acetaminophen?
Acetaminophen reduces fever by inhibiting the formulation and release of prostaglandins in the CNS and by inhibition endogenous pyrogens and the hypothalamic thermoregulator centre
It’s a safe and effective analgesic and antipyretic that causes a 1-2ºC decrease in temperature
What is the onset, time to peak, duration of acetaminophen?
Oral: 30 minutes
PR: slowly and incompletely absorbed
Time to peak: 3 hours
Duration: 4-6 hours
It is extensively metabolized by the liver
It is rapidly and completely absorbed from the GI tract
What is the adult dosing for acetaminophen?
325-650 mg q4-6h PRN (max 4g/24 hours)
New dosing guidelines being discussed
What is the pediatric dosing for acetaminophen?
PO/PR 10-15 mg/kg/dose given q4-6h PRN
Max 65 mg/kg/day (max 5 doses/24 hours)
How safe is acetaminophen?
Generally, considered a safe analgesic
Relatively safe for short term use in children, pregnancy and lactation
Dosing adjustment may be necessary for patients with renal dysfunction but not in the elderly
What are the adverse reactions of acetaminophen?
Adverse effects are considered rare. They include: allergic reaction, nausea and upper GI discomfort, serious skin reactions
What are clinically important drug interactions of acetaminophen?
Alcohol (increased hepatotoxicity)
Enzyme inducers (decreased acetaminophen levels)
Chronic use can occasionally enhance warfarin’s anticoagulant effect (rare)
What are possible causes for acetaminophen toxicity
Overdose
Disease and lifestyle (hepatitis, liver disease (cirrhosis), chronic alcohol use, binge drinking and fasting)
What are the available dosage forms of acetaminophen?
Immediate release tablet/caplet Extended-release caplet Gelcap Chewable tablet Rapidly-dissolving tablet Liquid Rectal suppository
What are NSAIDs? What are examples of NSAIDs?
Non-steroidal anti-inflammatory drugs
Acetylsalicylic acid, ibuprofen, naproxen
What are the pharmacological properties of NSAIDs?
Analgesic, antiplatelet, antipyretic, anti-inflammatory (may require higher doses than often seen in OTC)
What is the MOA of ibuprofen?
Inhibits the COX enzyme in the periphery and CNS and thereby inhibits prostaglandin synthesis
It is a safe and effective analgesic and antipyretic, causes a 1-2ºC decrease in temperature
What is the OOA of ibuprofen?
Antipyretic: over an hour
Analgesic: within 60 minutes
Anti-inflammatory: 7 days or more (peak effect: 1-2 weeks)
What is the DOA of ibuprofen?
Time to peak: 2-4 hours
Duration: 6-8 hours
How is ibuprofen metabolized?
Liver
What is the adult dosing for ibuprofen?
For a fever: 200-400 mg/dose q4-6h PRN
Max: 1.2 g/day
What is the paediatric dosing for ibuprofen?
PO 5-10 mg/kg q6-8h PRN
Max: 40 mg/kg/day or 4 doses/24 hours
What are the adverse effects of ibuprofen?
Most frequent: abdominal pain with cramps, dizziness, heartburn, nausea, skin rash
Sodium and water retention, diarrhea, GI bleeding, headache, nervousness, allergic reactions, reduced renal function, acute renal failure
What are contraindications/precautions for ibuprofen?
CI/precaution: PUD, GI perforation or bleeding, hypersensitivity, bleeding disorders, concomitant alcohol use, patients relying on vasodilatory renal prostaglandins for renal function
Caution: CHF, hypertension, dehydration, decreased renal
What are the drug interactions of ibuprofen?
It can reduce ASA’s anti platelet effect
It can increase the risk of GI pain/ulceration when taken with alcohol and/or corticosteroids
Antihypertensive agents (the antihypertensive effect is inhibited, possible hyperkalemia)
Increase the risk of bleeding with anticoagulants
Increase the risk of nephrotoxicity with cyclosporine
It can increase the levels of lithium and/or methotrexate
What are the consequences of overdose?
Serious toxicity is unusual
GI disturbances, bleeding, CNS depression, bradycardia, seizures, drowsiness, liver dysfunction, hypotension, death
Children who are at greatest risk of ibuprofen related renal toxicity include what?
Dehydrated (avoid in children with diarrhea and vomiting)
Cardiovascular disease
Pre-existing renal disease
Concomitant use of other nephrotoxic agents
Those younger than 6 months
Can be ibuprofen be taken while pregnant/breastfeeding?
There’s a risk in the first and third trimester
It’s compatible with breastfeeding
What are the dosage forms of ibuprofen?
Tablets, caplets Gel caplets, liquid-gels Paediatric drops Children's suspension Chewable tablets
What is the MOA of ASA?
Inhibits the COX enzyme in the periphery and CNS
What is the OOA and DOA of ASA?
Onset: Within an hour
Time to peak: 3 hours
Duration: 4-6 hours
Can be ASA be used in children?
Not recommended in children. Avoid in children less than 18 years old who have a viral illness (due to Reye’s syndrome). The cause of fever is often unknown, therefore avoid ASA in children
What is Reye’s syndrome?
Rapidly progressive encephalopathy with cerebral oedema, hepatic dysfunction and metabolic derangements which begins several days after apparent recovery from a viral illness (especially varicella or influenza A or B)
Characterized by vomiting and confusion, quickly evolving to seizures and coma
Salicylate use identified as a major precipitating factor
What is the adult dosing for ASA?
325-650 mg q4-6h PRN
Max: 4 g/day
What are the adverse effects of ASA?
Most frequent: abdominal pain with cramps, heartburn, dyspepsia, GI irritation
GI bleeding, skin rash, allergic reaction, sodium and water retention, platelet dysfunction
What are contraindications and precautions for ASA?
Less than 18 years old, active GI lesions, history of recurrent GI lesions, bleeding disorders, hypersensitivity, concomitant alcohol use, patients relying on vasodilatory renal prostaglandins for renal function
Precaution in renal failure and severe hepatic insufficiency
What are the drug interactions of ASA?
Increase risk of GI pain/ulceration with alcohol and corticosteroids
Increase risk of gastroduodenal ulcers and bleeding with NSAIDs
Antihypertensives (antihypertensive effect is inhibited, possible hyperkalemia)
Increased risk of bleeding with anticoagulants
Increase levels of methotrexate
Decreased therapeutic effect of probenecid and sulfinpyrazone
What are signs of ASA overdose?
Tinnitus, hyperpyrexia, hyperventilation, acid-base disturbances, nausea/vomiting, dehydration, coma, seizures, bleeding, hepatoxicity, renal failure, hyper or hypoglycemia, death
Is ASA safe in pregnancy/breastfeeding?
Risk in first and third trimester (compatible at low doses)
Potential toxicity in breastfeeding
What is ASA-induced asthma?
30 minutes to 3 hours post ingestion of ASA, it’s possible to observe clinical syndrome characterized by the onset of asthma
It’s common in 5-20% of asthmatics with concomitant allergic rhinitis or nasal polyps
Prosposed mechansim: decrease in prostaglandins results in an increase in leukotrienes (important mediator in asthma and allergies)
What is the MOA of naproxen?
Same as ibuprofen
For adults only
What is the dosing for naproxen for adults 12-65 years?
1 tab (220 mg) q8-12h Max 2 tabs in a 24 hour period
What is the dosing for naproxen for adults over 65 years?
q12h
Max 2 tabs in a 24 hour period
What is the OOA of naproxen?
Unknown for fever (20 minutes for analgesic effects)
Is naproxen safe to take in pregnancy/breastfeeding?
Pregnancy risk factor C
Not recommended for breastfeeding
Describe renal tolerability of NSAIDs
Prostaglandins (PGs) are important for maintenance of renal blood flow and tubular transport of electrolytes. Increased PG release occurs to compensate for an increased level of angiotensin II and norepinephrine
NSAIDs inhibit this compensatory mechanism therefore they can lead to:
-renal and systemic vascular resistance
-increased BP
-worsening of pre-existing CHF
NSAIDs therefore often interfere with the effects of antihypertensive agents
What are the patients at risk of renal failure when using NSAIDs?
Volume depletion states
Severe congestive heart failure
Hepatic cirrhosis (with or without ascites)
Clinically significant dehydration
Creatinine clearance is less than 30 ml/min
Intrinsic renal disease secondary to diabetes nephrotic syndrome or hypertension
Should products for treatment of fever be alternated or combined?
It is not recommended due to safety issues with this practise
- risk of overdose
- medication errors due to complexity regimen
- increased side effects
What is considered first line for treatment of fever?
Consider acetaminophen first line therapy in:
- ASA-sensitive asthma
- gastritis or PUD
- increased risk of bleeding
- patients with renal dysfunction
- CV or hypertensive patients
- multiple concurrent therapy
- pregnant or breastfeeding (especially third trimester)
What are monitoring parameters?
Watch for the development of rash or allergic reactions
Side effects (GI intolerances, tinnitus)
Monitor patients with pre-existing co-morbid conditions (CHF, CV or pulmonary insufficiencies)
Improvement should be seen within 24-72 hours
Treatment should not be used for more than 3 days without referral to determine underlying cause
Comfort is the goal
Monitor for dehydration and seizures in children at risk
Should a child be woken up for treatment?
No, unless they are at risk for seizures
