Fever & Intro to Pain Flashcards
T or F: a fever is a condition
false - a symptom
Define: fever
1) a normal response to various circumstances - usually due to viral or bacterial infection
2) controlled response where the core temp of body is increased to a new set point and a new balance of heat loss and production is established
What oral temp classifies as a fever?
over 37.5 degrees C
over 38 degrees C (rectal temp)
how long do fevers usually last?
3 days
What rectal temp classifies as a fever?
over 38 degrees C
What axillary (armpit) temp classifies as a fever?
over 37.3 degrees C
What tympanic (ear) temp classifies as a fever?
over 38 degrees C
What is the recommended way to measure temp: for children aged 0 to 2 yrs
1) rectal
2) axillary
- tympanic not recommended
- can damage something
- ear canal is not fully developed so you won’t get the best reading
What is the recommended way to measure temp: for kids aged 2 to 5 yrs
1) rectal
2) axillary, tympanic
What is the recommended way to measure temp: older than 5 yrs
1) oral
2) axillary, tympanic
Explain the pathophysiology of a fever
- fever produced by pyrogens or either endogenous or exogenous origins
- endogenous pyrogens are proteins that induce fever (including interleukin-1, tumor necrosis factor alpha, interleukin-6, ciliary neurotropic factor and interferon gamma)
- exogenous pyrogens are chemicals produced by bacteria or by components of the organism (these then stimulate the release of endogenous pyrogens)
- prostaglandins of the E2 series (PGE2) are produced in response to circulating pyrogens and elevate the thermoregulatory set point in the hypothalamus
When the hypothalamus reaches it’s new set point - how does the body temp increase to reach the new set point?
- vasoconstriction of peripheral blood vessels
- shivering to increase heat production
- behavioural changes (putting on more clothes/blankets)
hyperthermia
increase in body temperature not due to the hypothalamus (ex. physical exertion)
List a few risk factors for fever
- bacterial infection
- viral infection
- cancer
- multisystem diseases (ex. rheumatic diseases, connective tissue disorders, anything that affects more than one system)
- medications
What age group do you want to refer if they have a fever?
babies less than 6 months old
You want to refer a fever lasting > ___ hours (with or without treatment)
72 (3 days)
You want to refer a fever lasting > ___ hours w/o obvious cause
24
You want to refer a fever > ___ degrees C
40.5
When else do you want to refer a fever?
- child appears ill, irritable, cries inconsolably
- child other symptoms that bother parents
- pt has persistent wheezing/cough
- pt has rash
- recently had chemo
- pt has other serious disease
- pt has recently travelled
- recently had surgery
- eaten raw/poorly cooked meat/fish
- recently started a new drug
Signs/symptoms associated with fever
- sweating
- headache
- fatigue
- pain
- discomfort
- dehydration
- chills
- febrile seizures
goals of therapy for fever?
- patient comfort
- reduce parental anxiety
- reduce metabolic demand caused by fever in its with CV (cardiovascular) or pulmonary disease
- prevent/alleviate fever-associated mental dysfunction in the elderly
Why is reducing temp not a goal of therapy?
- because the fever is fighting off infection
- it is providing an increased temp environment so bacteria or virus cannot survive
List some non-pharms for treating a fever
- remove excess clothing, blankets, bedding (keep cool and comfortable)
- increase fluid intake
- avoid physical exertion
- maintain normal room temp
antipyretic
used to prevent or reduce fever
how do antipyretic agents work to reduce body temp?
decreases prostaglandin synthesis by inhibiting the cyclooxyegenase (COX) enzyme
What are the only 2 therapeutic choices for managing fever in children
acetaminophen
ibuprofen
How do acetaminophen and ibuprofen help manage a fever?
reduce the hypothalamus set point
*they do not lower normal body temp
Why is regular/short term use of agents recommended?
to remain consistent in treating the fever
-intermittent use may cause swings in temp (which will put an increased metabolic demand on the body)
MOA for acetaminophen
inhibits the formulation and release of prostaglandins in the CNS and by inhibiting endogenous pyrogens and the hypothalamic thermoregulatory centre
What temp decrease can you expect from acetaminophen?
1-2 degrees C
Oral onset for acetaminophen
30 mins
Rectal onset for acetaminophen
slow onset and incompletely absorbed
acetaminophen: time to peak
3 hours
acetaminophen: duration
4-6 hours
acetaminophen: where is it metabolized
liver
acetaminophen: GI Tract?
rapidly and completely absorbed from the GI tract
acetaminophen: adult dosing
325 - 650 mg Q4 to 6H PRN
*max 4000 mg/day
acetaminophen: pediatric dosing
PO 10-15 mg/kg/dose Q4 to 6H PRN
Max:
65-75 mg/kg/day
OR
5 doses/day
*can never exceed adult dose - even if the weight calculates that you should
acetaminophen: safe in children?
yes - short term use tho
acetaminophen: safe in pregnancy and lactation
yes
acetaminophen: dosing adjustment may be needed for Pts with ???
renal dysfunction
*i.e. bad CrCl
acetaminophen & alcohol: ?
increased risk of hepatotoxicity
acetaminophen & enzyme inducers: ?
decreased acetaminophen levels
acetaminophen & warfarin: ?
chronic use can occasionally enhance warfarin’s anticoagulant effect (this is rare tho)
NSAIDS: include ?
ASA (acetylsalicylic acid)
ibuprofen
naproxen
NSAIDS: pharmacological properties ?
analgesic
anti platelet
antipyretic
anti-inflammatory
NSAIDS: how do they work?
act on COX enzyme which inhibits prostaglandin synthesis
Ibuprofen: MOA
-inhibits COX enzyme in periphery and CNS and thereby inhibits prostaglandin synthesis
Ibuprofen: temp decrease?
1-2 degrees celsius
Ibuprofen: onset as an antipyretic
less than 1 hour
Ibuprofen: onset as an analgesic
within 60 mins
Ibuprofen: onset as an anti-inflammatory
less than or equal to 7 days
-peak effect is at 1-2 weeks
Ibuprofen: time to peak
2-3 hours
Ibuprofen: duration
6-8 hours
Ibuprofen: metabolism?
liver
Ibuprofen: adult dosing for fever
200-400 mg/dose Q4 to 6H PRN
-max 1.2g/day (OTC dosing)
Ibuprofen: child dosing for fever
PO 5-10 mg/kg Q6 to 8H
max: 40 mg/kg/day or 4 doses/24 hr
**again cannot exceed adult dosing even if calculations based on weight say you should
Ibuprofen: things to consider?
- risk of kidney damage if pt becomes dehydrated so pt must stay hydrated on this med
- take with food - it can disrupt stomach lining and cause discomfort
Ibuprofen & ASA
decrease ASA’s anti platelet effect
Ibuprofen & (alcohol and corticosteroids)
increased risk of GI pain/ulceration
Ibuprofen & antihypertensive agents (beta-blocker, ACEI, diuretics, vasodilators)
- antihypertensive effect is inhibited
- possible hyperkalemia with ACEI and K+ sparing diuretics
Ibuprofen & anticoagulant
increased risk of of bleeding
Ibuprofen & cyclosporine
increased levels/ risk of nephrotoxicity
Ibuprofen & lithium, methotrexate
increased levels
Ibuprofen: children at greatest risk of ibuprofen related renal toxicity include ?
- dehydrated children (avoid in children with diarrhea/ vomiting)
- CVD
- preexisting renal disease
- concomitant use of other nephrotoxic agents
- those younger than 6 months
Ibuprofen: always take with ?
food man
Ibuprofen: compatible in pregnancy?
risk in 1st and 3rd trimester
*if pt is pregnant - acetaminophen is a better choice
Ibuprofen: compatible in breastfeeding?
yes
ASA: MOA ?
inhibits the COX enzyme in the periphery and CNS
ASA: onset
within 1 hour
ASA: time to peak
3 hours
ASA: duration
4-6 hours
ASA: ok for children?
no!
never recommend for children due to Reye’s syndrome
Reye’s syndrome
- rapidly progressive encephalopathy (disorder of the brain) with cerebral edema, hepatic dysfunction and metabolic derangements which begins several days after apparent recovery from a viral illness
- characterized by vomiting and confusion evolving to seizures and coma
- salicylate use identified as a major precipitating factor
ASA: adult dosing
325 - 650 mg q4 to 6h PRN
max 4000 mg/day
ASA: children dosing
not recommended
ASA & alcohol and corticosteroids
increased risk of GI pain/ulceration
ASA & NSAIDs, including COX-2 inhibitiors
increased risk of gastroduodenal ulcers and bleeding
ASA & anti-hypertensive agents (beta-blockers, ACEI, diuretics, vasodilators)
- antihypertensive effect inhibited
- possibl ehyperkalemia with ACEI and potassium sparing diuretics
ASA & anticoagulants
increased risk of bleeding
both blood thinners?
ASA & methotrexate
increased levels
ASA & probenecid, sulfinpyrazone
decreased therapeutic effect of these agents
ASA - always take with ____
food
ASA compatible in pregnancy?
Risk in 1st and 3rd trimester (at a full dose)
Compatible at low dose
ASA compatible in breastfeeding?
limited data
potential toxicity
What is ASA-induced asthma?
onset of asthma 30mins-3 hours post ingestion of ASA
What is the proposed mechanism for this rxn (ASA-induced asthma) ?
decreased PG (prostaglandins) results in increased leukotrienes (important mediator in asthma and allergies)
Who does ASA-induced asthma affect?
5-20% of asthmatics with concomitant allergic rhinitis (AR) or nasal polyps
branded version of naproxen
aleve
standard dose of naproxen?
220mg
Is aleve for adults only?
yes
What is the dosing for naproxen?
ages:12-65
220 mg every 8-12 hrs
age: >65 (renal insufficiencies)
220mg every 12 hrs
*max 2 tabs per 24 hours
Onset of action for aleve?
unknown for fever
20 mins for analgesic affect
Take naproxen with food?
yes
and water obvs
Naproxen in pregnancy?
compatible
Naproxen in breastfeeding?
not recommended
Don’t take naproxen if …?
allergic to ASA or other NSAIDs
What patients are at risk of renal failure when using NSAIDs?
- volume depletion states
- severe congestive heart failure (CHF)
- hepatic cirrhosis
- creatinine clearance < 30 mL/min
- intrinsic renal disease secondary to diabetes, nephrotic syndrome or hypertension (HTN)
What is used as first line therapy ?
Acetaminophen
Consider acetaminophen as first line treatment in patients that are:
??
- ASA-sensitive asthma
- gastritis of PUD
- inceased risk of bleeding
- pts with renal dysfunction
- CV or hypertensive patients
- multiple concurrent drug therapy
- prego or breastfeeding women (especially 3rd trimester)
