2. Background
• Feverish illness in children:
• is the most common reason for children to be
taken to the doctor
• is a cause of concern for parents and carers
• Fever occurs in response to infection, injury, or
inflammation and has many causes.
• can be a result of a simple self-limiting
infection or a life-threatening disorder.
3. DEFINITION OF FEVER
• Fever is an elevation of body
temperature that exceeds the normal
daily variation, in conjunction with an
increase in hypothalamic set point.
• Fever is defined as a before-noon
temperature of more than 37.2°C or an
after-noon temperature of more than
37.7°C .
4. Important Notes
• Fever without localizing signs (without a focus),
frequently occurring in a child younger than 3 years
old, in which a history and physical examination fail to
establish a cause, although a diagnosis of occult
bacteremia may be suggested by laboratory studies
• Fever of unknown origin (FUO), which defines fever
for more than 14 days without an identified etiology
despite history, physical examination, and routine
laboratory tests or after 1 week of hospitalization and
evaluation.
• Fever can be classified depend on whether it has
lasted 7 days or less (acute) or more than 7 days
(chronic).
5. Important Notes
• Bacteremia is defined as a positive blood culture
and may be primary or secondary to a focal
infection.
• Sepsis is the systemic response to infection that is
manifested by hyperthermia or hypothermia,
tachycardia, tachypnea, and shock.
• Children with septicemia and signs of CNS
dysfunction (irritability, lethargy), cardiovascular
impairment (cyanosis, poor perfusion), and
disseminated intravascular coagulation
(petechiae, ecchymosis) are readily recognized as
toxic appearing or septic.
6. Pathophysiology
• Core body temperature is normally
maintained within 1°C to 1.5°C in a range of
37°C to 38°C.
• Normal body temperature is often considered
to be 37°C .
• Rectal temperatures greater than 38 °C
(>100.4°F) generally are considered abnormal.
7. VARIATION IN TEMPERATURE
• There is normal diurnal variation, with maximum
temperature in the late afternoon.
• Maximum normal oral temperature
• At 6 AM : 37.2
• At 4 PM : 37.7
• Anatomic variation
• Physiologic variation:
• Age
• Sex
• Exercise
• Circadian rhythm
• Underlying disorders
8. Pathophysiology
• The normal body temperature is maintained
by a complex regulatory system in the anterior
hypothalamus.
• Development of fever begins with the release
of endogenous pyrogens into the circulation
as the result of infection, inflammatory
processes (rheumatic disease), or malignancy.
9. Pathophysiology
• Microbes and microbial toxins act as exogenous pyrogens
by stimulating release of endogenous pyrogens, which
include cytokines such as interleukin-1, interleukin-6,
tumor necrosis factor, and interferons that are released by
monocytes, macrophages, mesangial cells, glial cells,
epithelial cells, and B lymphocytes.
• Endogenous pyrogens reach the anterior hypothalamus via
the arterial blood supply, liberating arachidonic acid, which
is metabolized to prostaglandin E2, resulting in an elevation
of the hypothalamic thermostat.
• Endotoxin stimulates endogenous pyrogen release and
directly affects ther-moregulation in the hypothalamus.
11. ACUTE PHASE RESPONSE
• Metabolic changes
– Negative nitrogene
balance
– Loss of body weight
• Altered synthesis of
hormones
• Hematologic alterations
– Leukocytosis
– Thrombocytosis
– Decreased
erythrocytosis
• Altered hepatocyte function
(Acute phase reactants)
– C reactive protein(increased)
– Serum amyloid A(increased)
– Fibrinogen(increased)
– Fibronectin(increased)
– Haptoglobin(increased)
– Ceruloplasmin(increased)
– Ferritin(increased)
– Albumin(decreased)
– Transferrin(decreased)
12. DISCOMFORT DUE TO FEVER
• For each 1 °C elevation of body temperature:
–Metabolic rate increase 10-15%
–Insensible water loss increase
300-500ml/m2/day
–O2 consumption increase 13%
–Heart rate increase 10-15/min
13. ATTENUETED FEVER RESPONSE
• Fever may not be present despite infection in:
–Newborn
–Elderly
–Uremia
–Significant malnourished individual
–Taking corticosteroids
14. Benefits of fever
• Benefits of fever
– Protective role in the immune system
• Inhibition of growth and replication of microorganisms
• Aids in body’s acute phase reaction
• Enhanced immunologic function of wbc’s
– lymphocyte response to mitogens
– bactericidal activity of neutrophils
– production of interferon
• Promotion of monocyte maturation into macrophages
• Promotion of lymphocyte activation and antibody
production
• Decreased availability of free iron for bacterial replication
15. HOW TO TAKE A CHILD’S
TEMPERATURE
• A child's temperature can be taken:
• from the rectum, ear, mouth, forehead, or
armpit.
• It can be taken with a glass or digital
thermometer.
16. • Glass thermometers need to be shaken before
use to make sure the temperature they show is
below the normal body temperature (98.6° F, or
about 37° C). Then they must be left in place for 2
to 3 minutes.
• Digital thermometers are easier to use and give
much quicker readings (and usually give a signal
when they are ready).
• Glass thermometers containing mercury are no
longer recommended because they can break
and expose people to mercury.
17. • Oral temperatures are taken by placing a glass
or digital thermometer under the child's
tongue. Oral temperatures provide reliable
readings but are difficult to take in young
children. Young children have difficulty
keeping their mouth gently closed around the
thermometer, which is necessary for an
accurate reading. The age at which oral
temperatures can be reliably taken varies from
child to child but is typically after age 4.
18. • Rectal temperatures are most accurate. That is, they
come closest to the child's true internal body
temperature. For a rectal temperature, the bulb of the
thermometer should be coated with a lubricant. Then
the thermometer is gently inserted about 1/2 to 1 inch
(about 1 1/4 to 2 1/2 centimeters) into the rectum
while the child is lying face down. The child should be
kept from moving.
• Ear temperatures are taken with a digital device that
measures infrared radiation from the eardrum. Ear
thermometers are unreliable in infants under 3 months
old. For an ear temperature, the thermometer probe is
placed around the opening of the ear so that a seal is
formed, then the start button is pressed. A digital
readout provides the temperature.
19. • Forehead (temporal artery) temperatures are taken with a
digital device that measures infrared radiation from an
artery in the forehead (the temporal artery). For a forehead
temperature, the head of the thermometer is moved lightly
across the forehead from hairline to hairline while pressing
the scan button. A digital readout provides the
temperature. Forehead temperatures are not as accurate
as rectal temperatures, particularly in infants under 3
months old.
• Armpit temperatures are taken by placing a glass or digital
thermometer in the child's armpit, directly on the skin.
Doctors rarely use this method because it is less accurate
than others (readings are usually too low and vary greatly).
However, if caretakers are uncomfortable taking a rectal
temperature and do not have a device to measure ear or
forehead temperature, measuring armpit temperature may
be better than not measuring temperature at all.
20. Thermometers ? Age
Oral and rectal temperature measurements
• Do not routinely use the oral and rectal routes to measure
the body temperature of children aged 0–5 years.
• Measurement of body temperature at other sites
• In infants under the age of 4 weeks, measure body
temperature with an electronic thermometer in the axilla.
In children aged 4 weeks to 5 years, measure body
temperature by one of the following methods:
• electronic thermometer in the axilla
• chemical dot thermometer in the axilla
• infra-red tympanic thermometer.
21. • Healthcare professionals who routinely use
disposable chemical dot thermometers should
consider using an alternative type of
thermometer when multiple temperature
measurements are required.
• Forehead chemical thermometers are
unreliable and should not be used by
healthcare professionals.
22. Grades of Fever
• A fever may be classified as mild (or 'low
grade') if it's between 37.8°C and 38.5°C; or
• high (or 'high-grade') above 38.5°C.
• very high: body temperatures in excess of
41°C,
23. • The pattern of fever in children may vary depending on the age of
the child and the nature of the illness.
• Neonates may not have a febrile response and may be hypothermic
despite significant infection,
• whereas older infants and children younger than 5 years old may
have an exaggerated febrile response with temperatures of up to
105°F (40.6°C) in response to either a serious bacterial infection or
an otherwise benign viral infection.
• Fever to this degree is unusual in older children and adolescents
and suggests a serious process.
• The fever pattern does not distinguish fever caused by bacterial,
viral, fungal, or parasitic organisms from that resulting from
malignancy, autoimmune diseases, or drugs.
PATTERN OF FEVER
24. • Sustained (Continuous) Fever
• Intermittent Fever (Hectic Fever)
• Remittent Fever
• Relapsing Fever:
– Tertian Fever
– Quartan Fever
– Days of Fever Followed by a Several Days Afebrile
– Pel Ebstein Fever
– Fever Every 21 Day
PATTERN OF FEVER
25. • The pattern of fever may vary in different conditions and could assist in
the diagnosis of the cause of the fever. Some of the types of fever are
listed below:
Continuous fever: Fever that does not fluctuate more than 1°C in 24 hours
is called continuous fever. It is seen in conditions like pneumonia, typhoid,
urinary tract infections and infective endocarditis.
Remittent fever: Fever that fluctuates more than 1°C in 24 hours is
referred to as remittent fever. Causes include typhoid and infectious
mononucleosis.
Intermittent fever: Fever that is present only for some time in the day is
called intermittent fever. Malaria caused by Plasmodium vivax results in
fever every third day and that caused by Plasmodium malariae results in
fever every fourth day.
PATTERN OF FEVER
26. • Hectic or septic fever: Fever variation between the highest and
lowest temperatures is very large and more than 5°C. This type of
fever is seen in septicemia.
Pel Ebstein fever: The febrile and afebrile periods alternate and
follow a definite pattern. For example, in Hodgkin’s disease and
other lymphomas, fever for 3 to 10 days is followed by a fever-free
period of 3 to 10 days, with the same cycle repeating.
• Fever with rigors: Rigor is the shaking or excessive shivering that
accompanies fever. Fever accompanied with rigors are seen in
conditions like malaria, kala azar, filariasis, urinary tract infections,
inflammation of gall bladder, septicemia, infective endocarditis or
inflammation of the inner layer of the heart, abscesses and
pneumonia.
27. a) Fever continues
b) Fever continues to
abrupt onset and
remission
c) Fever remittent
d) Intermittent fever
e) Undulant fever
f) Relapsing fever
28. • Personal History:
– Age
– Occupation
– Place of origin,Travel
History
– Habits: Consumption of
Unpasteurized Dairy
Products.
• Underlying Diseases:
– Splenectomy
– Surgical Implantation of
Prosthesis
– Immunodeficiency
– Chronic Diseases:
• Cirrhosis
• Chronic Heart Diseases
• Chronic Lung Diseases
APPROACH TO FEVER
29. • Drug History:
• Antipyretics
• Immunosuppressants
• Antibiotics
• Family History:
• TB in the Family
• Recent Infection in
the Family
• Associated Symptoms:
• Shaking chills
• Ear pain,Ear
drainage,Hearing loss
• Visual and Eye
Symptoms
• Sore Throat
• Chest and Pulmonary
Symptoms
• Abdominal Symptoms
• Back pain, Joint or
Skeletal pain
APPROACH TO FEVER
30. • Physical Examination:
– Vital Signs
– Neurological Exam.
– Skin Lesions,Mucous Membrane
– Eyes
– ENT
– Lymphadenopathy
– Lungs and Heart
– Abdominal Region (Hepatomegaly,Splenomegaly)
– Musculoskeletal
APPROACH TO FEVER
31. • LABORATORY STUDY:
• Assess the extent and severity of the
inflammatory response to infection
• Determine the site(s) and complications of
organ involvement by the process
• Determine the etiology of the infectious
disease.
APPROACH TO FEVER
32. Clinical assessment of the child with
fever
• Check for any immediately life-threatening
features.
• Use traffic light system to check for symptoms
and signs that predict the risk of serious illness.
• Look for a source of fever and check symptoms
and signs associated with specific diseases.
• Measure and record temperature, heart rate,
respiratory rate, capillary refill time and assess for
dehydration.
33. The Traffic Light System
Tool for identifying the likelihood of serious illness
Children with only symptoms and signs in the
‘green’ column are at low risk
Children with one or more symptom or sign in the
‘amber’ column are at intermediate risk
Children with one or more symptom or sign in the
‘red’ column are at high risk
34. Traffic light system:
Colour Normal colour of skin, lips and tongue
Activity
Responds normally to social cues
Content/smiles
Stays awake or awakens quickly
Strong/normal cry/not crying
Hydration
Normal skin and eyes
Moist mucous membranes
Other None of the amber or red symptoms or signs
35. Traffic light system:
Colour Pallor reported by parent/carer
Activity
Not responding normally to social cues
Wakes only with prolonged stimulation
Decreased activity
No smile
Respiratory
Nasal flaring
Tachypnoea: RR> 50/min age 6-12 months,
RR> 40/min age >12 months
Oxygen saturation ≤ 95% in air
Crackles
Hydration
Dry mucous membranes
Poor feeding in infants
CRT ≥3 seconds
Reduced urine output
Other
Fever for ≥5 days
Swelling of a limb or joint
Non-weight bearing/not using an extremity
A new lump >2cm
36. Traffic light system:
Colour Pale/mottled/ashen/blue
Activity
No response to social cues
Appears ill to a healthcare professional
Unable to rouse or if roused does not stay awake
Weak/high pitched/continuous cry
Respiratory
Grunting
Tachypnoea: RR>60 /min
Moderate or severe chest indrawing
Hydration Reduced skin turgor
Other
Age 0-3 months, temperature ≥38°C
Age 3-6 months, temperature ≥39°C
Non blanching rash Bulging fontanelle
Neck stiffness Status epilepticus
Focal neurological signs Focal seizures
Bile-stained vomiting
37. Symptoms and signs
of specific diseases
Meningococcal
disease
Non-blanching rash, particularly with one or more of the
following:
•an ill-looking child
•lesions >2 mm in diameter (purpura)
•a CRT of ≥3 seconds
•neck stiffness
Meningitis
Neck stiffness
Bulging fontanelle
Decreased level of consciousness
Convulsive status epilepticus
Herpes simplex
encephalitis
Focal neurological signs
Focal seizures
Decreased level of consciousness
Pneumonia
Tachypnoea Chest indrawing
Crackles Cyanosis
Nasal flaring Oxygen saturation ≤95%
38. Symptoms and signs
of specific diseases (2)
Urinary tract
infection (in
children aged
older than 3
months)
Vomiting
Poor feeding
Lethargy
Irritability
Abdominal pain or tenderness
Urinary frequency or dysuria
Offensive urine or haematuria
Septic arthritis/
osteomyelitis
Swelling of a limb or joint
Not using an extremity
Non-weight bearing
Kawasaki
disease
Fever >5 days and at least four of the following:
•bilateral conjunctival injection
•change in upper respiratory tract mucous
membranes
•change in the peripheral extremities
•polymorphous rash
•cervical lymphadenopathy
39. Management of children 3 months
to 5 years
Perform test for urinary
tract infection.
Assess for pneumonia.
Do not perform routine
blood tests or chest X-ray.
Perform (unless deemed unnecessary)
urine test for urinary tract infection
full blood count
blood culture
C-reactive protein.
Perform chest x-ray if fever higher than 39°C
and white blood cell count greater
than 20 x 109/litre.
Consider lumbar puncture if child is younger
than 1-year old.
Perform:
blood culture
full blood count
urine test for urinary tract infection
C-reactive protein.
Consider the following, as guided by
clinical assessment:
lumbar puncture in children of all ages
chest X-ray
serum electrolytes
blood gas.
Consider admission. If admission is not necessary
but no diagnosis has been reached, provide a safety
net for the parents/carers.
If no diagnosis is reached,
manage the child at home with
appropriate care advice.
Assess: look for life-threatening, traffic light and specific diseases symptoms and signs
40. Management of children under
3 months
Assess: look for life-threatening, traffic light and specific diseases symptoms and signs
Observe and monitor:
temperature
heart rate
respiratory rate.
Perform:
full blood count
C-reactive protein
blood culture
urine test for urinary tract infection
chest X-ray if respiratory signs are present
stool culture if diarrhoea is present.
Admit, perform lumbar puncture and start parenteral antibiotics if the child is:
younger than 1-month old
1–3 months old appearing unwell
1–3 months old and with a white blood cell count of less than 5 or greater than 15 x 109/litre
Whenever possible, perform lumbar puncture before the administration of antibiotics
41. FEVER IN INFANTS YOUNGER THAN 3
MONTHS OLD
• Fever or temperature instability in infants younger than 3 months
old is associated with a higher risk of serious bacterial infections
than in older infants.
• These younger infants usually exhibit only fever and poor feeding,
without localizing signs.
• Most febrile illnesses in this age group are caused by:
• common viral pathogens,
• but serious bacterial infections that are seen frequently include
bacteremia (caused by S. pneumoniae, Hib, nontyphoidal
Salmonella, group B streptococcus, or N. meningitidis), UTI
(Escherichia coli), pneumonia (S. aureus, S. pneumoniae, or group B
streptococcus), meningitis (S. pneumoniae, Hib, group B
streptococcus, meningococcus, herpes simplex virus [HSV],
enteroviruses), bacterial diarrhea (Salmonella, Shigella, E. coli), and
osteomyelitis or septic arthritis (S. aureus or group B
streptococcus).
42. • Differentiation between viral and bacterial infections in
young infants is difficult.
• Febrile infants younger than 3 months old who appear
ill and all febrile infants younger than 4 weeks old
usually are admitted to the hospital for empirical
antibiotics pending culture results, especially if there is
uncertainty of follow-up.
• After blood, urine, and CSF specimens are obtained for
culture, broad-spectrum parenteral antibiotics
(cefotaxime and ampicillin) are administered.
• The choice of antibiotics depends on the pathogens
suggested by localizing findings, which may indicate
possible pneumonia, infectious arthritis, osteomyelitis,
or meningitis.
43. • Well-appearing febrile infants 4 weeks of age or older:
• without an identifiable focus, with good follow-up, with no
history of prematurity or prior antimicrobial therapy,
• with a white blood cell (WBC) count of 5000 to 15,000/μL,
with urine with less than 10 WBCs/high-power field, with
stool with less than 5 WBCs/high-power field (for infants
with diarrhea), and
• with normal chest x-ray (for infants with respiratory signs)
• may be followed as outpatients without empirical
antibiotic treatment or sometimes are treated with the
long-acting antibiotic ceftriaxone given intramuscularly.
• Regardless of antibiotic treatment, close follow-up for at
least 72 hours, including re-evaluation in 24 hours or
immediately with any clinical change, is essential
44. FEVER IN CHILDREN YOUNGER THAN 3
YEARS OLD
• A common clinical pediatric problem is the evaluation
of a febrile but well-appearing child younger than 3
years old with no localizing signs of infection.
• Although most of these children have self-limited viral
infections, some have occult bacteremia (bacteremia
without an identifiable focus), and a few have severe
and potentially life-threatening illnesses, such as
bacterial meningitis. Particularly in the early stages of
such illness, it is difficult even for experienced clinicians
to differentiate patients with bacteremia from patients
with benign illnesses.
45. • Children between 2 months and 3 years of age
are at increased risk for infection with organisms
with polysaccharide capsules, including S.
pneumoniae, Hib, N. meningitidis, and
nontyphoidal Salmonella.
• Effective phagocytosis of these organisms
requires opsonic antibody. Transplacental
maternal IgG initially provides immunity to these
organisms, but as the IgG gradually dissipates
over the first several months of life, the infant is
at increased risk for infection.
• In this age group, the most common identified
serious bacterial infection is a urinary tract
infection.
46. • Most episodes of fever in children younger
than 3 years old have a demonstrable source
of infection that is elicited by history or
physical examination or a simple laboratory
test; usually a common cold, otitis media,
pneumonia, or UTI.
• Among well-appearing febrile children 3 to
36 months old without localizing signs,
approximately 1.5% have occult bacteremia.
• Risk factors for occult bacteremia include
temperature 102.2°F (39°C) or greater, WBC
count 15,000/mm3 or greater, and elevated
absolute neutrophil count, band count, ESR, or
CRP.
47. • Occult bacteremia in otherwise healthy
children is usually transient and self-limited,
but may progress to serious localizing
infections, such as pneumonia, meningitis,
infectious arthritis, and pericarditis.
• All children with fever without localizing signs
should have blood culture and urinalysis and
urine culture to evaluate for a UTI.
• Patients with diarrhea should have a stool
evaluation for leukocytes.
48. • Ill-appearing children should be admitted to the
hospital and treated with antibiotics.
• Well-appearing children usually are followed as
outpatients without empirical antibiotic treatment or
sometimes treated with IM ceftriaxone.
• Regardless of antibiotic treatment, close follow-up for
at least 72 hours, including re-evaluation in 24 hours or
immediately with any clinical change, is essential.
• Children with a positive blood culture require
immediate reevaluation, repeat blood culture,
consideration for lumbar puncture, and empirical
antibiotic treatment.
49. TREATMENT OF FEVER
• Most fevers are associated with self-limited
infections, most commonly of viral origin.
• If the fever results from a disorder, that
disorder is treated
50. • Reasons not to treat fever:
– The growth and virulance of some organisms
– Host defense-related response
– Fever is an indicator of disease
– Adverse effect of antipyretic drugs
– Iatrogenic stress
– Social benefits
TREATMENT OF FEVER
51. • Reasons to treat fever:
– The individual with pulmonary or cardiovascular disease
– The patient at additional risk from the hypercatabolic state
(Poor nutrition, Dehydration)
– The young child with a history of febrile convulsions
– Toxic encephalopathy or delirium
– For the patient comfort
– Hyperpyrexia
TREATMENT OF FEVER
52. • General measures:
• Drinking plenty of clear fluids to replace fluids lost by sweating,
vomiting or diarrhoea – either water, or an oral rehydration solution
which contains electrolytes.
• Changing clothing and bed linen frequently.
• Tepid baths (but don't use cold water, as this can increase core body
temperature by cooling the skin and causing shivering).
• Keeping clothes and blankets to a minimum.
• Avoiding hot water bottles or electric blankets (which may raise
body temperature further).
• Ventilating the room.
• There are many other unhelpful folk remedies, ranging from the
harmless (for example, putting onions or potatoes in the child's
socks) to the uncomfortable (for example, coining or cupping).
TREATMENT OF FEVER
53. • Drugs to lower fever:
• Typically, the following drugs are used:
• Acetaminophen, given by mouth or by
suppository
• Ibuprofen, given by mouth
• Rarely, acetaminophen or ibuprofen is
given to prevent a fever, as when infants
have been vaccinated.
• Aspirin is no longer used for lowering
fever in children because it can interact
with certain viral infections (such as
influenza or chickenpox) and cause a
serious disorder called Reye syndrome
TREATMENT OF FEVER
54. Treatment Strategies
• Acetaminophen is generally a first-line
antipyretic due to being well tolerated
with minimal side effects.
• Pediatric dose: 10-15mg/kg q4-6h.
• Ibuprofen:
• 5-10 mg/kg/dose orally every 6 to 8 hours as
needed
55. FEVER and ILLNESS
• Antipyretics may prolong course of illness??
– Adults with rhinovirus shed the virus longer
– Children with varicella have delayed time for
lesions to crust (about 1 day)
– Children with malaria take longer to clear
parasites (75 vs 59 hours)
56. Fever of unknown origin (FUO)?
• What is fever of unknown origin (FUO)?
Fever of unknown origin (FUO) was defined as ‘fever with a temperature
of more 101°F on several occasions, lasting more than 3 weeks, which
includes a hospital stay of more than 1 week with a failure to diagnose the
cause’ by Petersdorf and Beeson in 1961.
Durack and Street proposed a revised system of classification of FUO.
Accordingly, FUO includes:
1) Classic FUO
2) Nosocomial FUO
3) Neutropenic FUO
4) FUO associated with HIV infection
57. Classic FUO
• Definition:
–Fever of 38.3 C or higher on several
occasions
–Fever of more than 3 weeks duration
–Diagnosis uncertain, despite
appropriate investigations after at least
3 outpatient visits or at least 3 days in
hospital
58. Nosocomial FUO
• Definition:
–Fever of 38.3 or higher on several
occasions
–Infection was not manifest or
incubating on admission
–Failure to reach a diagnosis despite 3
days of appropriate investigation in
hospitalized patient
59. Neutropenic FUO
• Definition:
–Fever of 38.3 or higher on several
occasions
–Neutrophil count is <500/mm3 or is
expected to fall to that level in 1 to 2
days
–Failure to reach a diagnosis despite 3
days of appropriate investigation
60. HIV-Associated FUO
• Definition:
–Fever of 38.3 or higher on several
occasions
–Fever of more than 3 weeks for
outpatients or more than 3 days for
hospitalized patients with HIV infection
–Failure to reach a diagnosis despite
3days of appropriate investigation
61. “Fever is nature’s engine
which she brings into the
field to remove her
enemy”
Thomas Sydenham
English Physician
1624 - 1689