When a person has a fever, the pulse usually increases along with the temperature. Relative bradycardia refers to a pulse-temperature deficit, with the pulse less than that expected for a given temperature.
Criteria for using relative bradycardia in clinical diagnosis:
(1) age of patient >= 13 years
(2) temperature >= 102°F and <= 106°F
(3) The pulse is taken simultaneously with the temperature,
(4) The patient has normal sinus rhythm with no arrhythmias, second or third degree heart block, or pacemaker.
|
Temperature
|
Pulse in Beats per Minute
|
|
102°F (38.9 °C)
|
110
|
|
103°F (39.5 °C)
|
120
|
|
104°F (40.0 °C)
|
130
|
|
105°F (40.6 °C)
|
140
|
|
106°F (41.1 °C)
|
150
|
pulse in beats per minute =
= (10 * (temperature in °F)) – 910
Infectious causes of relative bradycardia:
(1) Legionnaires' disease
(2) psittacosis
(3) Q fever
(4) typhoid fever
(5) typhus
(6) malaria
(7) babesiosis
(8) leptospirosis
(9) yellow fever
(10) dengue fever
(11) Rocky Mountain spotted fever
Noninfectious causes of relative bradycardia:
(1) beta-blockers
(2) CNS lesions
(3) malignant lymphoma
(4) factitious fever
(5) drug-related fever
Relative bradycardia is not found with the "typical" bacterial pneumonias.
