Basics of the graphical method
To assess a febrile state in clinical practice, a temperature chart is used. This is a special form on which a graph is plotted reflecting the dynamics of the patient's condition.
- Abscissa axis (X): reflects time. It records observation days, with each 24-hour period divided into two key measurements — morning and evening.
- Ordinate axis (Y): shows the body temperature level in degrees Celsius.
By connecting the points of daily measurements, the physician obtains a clear temperature curve. The graph also allows tracking the variants of fever termination, such as a sharp drop (crisis) during the recovery period.
Highly stable fevers
This group includes conditions where the graph remains at consistently high levels, and the daily fluctuation range is not very large.
Continuous fever (febris continua) Characterized by persistently high values (within 38–39 °C). The difference between morning and evening values does not exceed 1 °C. The graph runs smoothly, without significant drops. This type is typical for acute infectious diseases such as lobar pneumonia or acute respiratory viral infections (ARVI).
Remittent fever (febris remittens) High numbers are also recorded here, but daily fluctuations are more pronounced and range from 1 to 2 °C. A crucial diagnostic sign: despite noticeable fluctuations, the baseline of the graph never drops to normal values. Most often, such a curve accompanies purulent diseases.
Alternation of fever and normal temperature
These types are characterized by an alternation of high fever episodes and periods of normalization (apirexia).
Intermittent fever (febris intermittens) Graphically looks like sharp peaks ("spikes") with deep drops to normal.
- Onset: sudden rise to 39–40 °C.
- Duration: the fever lasts several hours.
- Decline: rapid (critical) decrease to normal or subnormal figures (below 36.0 °C).
- Apirexia: normal condition persists for 1–3 days, then the cycle repeats. This is a classic marker of malaria.
Recurrent fever (febris recurrens) The graph forms wide "trapeziums" or blocks rather than sharp peaks.
- Duration: the febrile period (plateau) steadily holds for several days.
- Following a temporary drop to normal, a new wave ensues (usually 2 to 5 waves). This picture is characteristic of certain spirochetoses (e.g., relapsing fever).
Fevers with wide fluctuations and a specific rhythm
This category gathers curves with extreme amplitudes, distorted rhythms, or a lack of a strict system.
- Hectic or exhausting fever (febris hectica): characterized by a huge amplitude. Daily fluctuations amount to 3–5 °C, with drops reaching normal or subnormal figures. This is a specific sign of severe infections, primarily — sepsis.
- Undulant fever (febris undulans): has a cyclic character, but changes occur gradually. The temperature smoothly rises day by day and then just as smoothly decreases (unlike the sharp jumps in recurrent fever). Typical for brucellosis.
- Irregular fever (febris irregularis): the most common type without any regularity. Chaotic rises and falls (often in the 37–40 °C range). Encountered in influenza, rheumatism, dysentery.
- Inverted fever (febris inversa): disturbance of the circadian rhythm of thermoregulation. Unlike normal, the morning temperature turns out to be higher than the evening one. Indicates severe chronic processes: tuberculosis or protracted sepsis.
Briefly: answers to topical questions
What are the stages of fever progression?
There are three main stages of fever progression.
- Stage I — temperature rise (st. incrementi): elevation of body temperature; at this stage, it is driven by a shift in the ratio between heat production and heat loss.
- Stage II — elevated temperature: the period of sustained temperature plateau.
- Stage III — temperature decrease: decline of temperature to the normal range.
What is the difference between a critical drop in temperature (crisis) and a lytic drop (lysis)?
A critical decrease in temperature differs from a lytic decrease in speed, mechanism, and risks.
- Critical decrease (crisis) — rapid, occurring within several hours. Associated with the sharp activation of heat loss: pronounced dilation of skin arterioles and profuse sweating. Can lead to a sharp decrease in venous return to the heart, a drop in blood pressure, and collapse.
- Lytic decrease (lysis) — gradual, taking place over several days. Encountered more frequently and is more favorable for the organism.
What clinical parameters, in addition to body temperature, are recorded in the patient's temperature chart?
In addition to body temperature, a number of other parameters are recorded in the patient's temperature chart as graphs and figures.
- Pulse — graphical parameter, marked in red.
- Blood pressure — recorded graphically.
- Respiratory rate — recorded in text as numerical values.
- Fluid balance — digital values of daily diuresis and fluid intake.
- Stool frequency — numerical parameter.
- Body weight — numerical parameter.
Additionally, key symptoms (edema, rashes, bleeding) and main prescriptions are entered.
What types is fever divided into according to the degree of temperature elevation (subfebrile, febrile, etc.)?
According to the degree of body temperature elevation, fever is divided into four main types.
- Subfebrile (mild) — temperature elevation from normal up to 38 °C.
- Febrile (moderate) — temperature values within 38–39 °C.
- Pyretic (high) — temperature values ranging from 39–41 °C.
- Hyperpyretic (extreme) — elevation above 41 °C, which represents a life-threatening condition for the organism.
To easily distinguish intermittent fever from recurrent fever, focus on the duration. In intermittent fever, the fever lasts for hours (narrow "spikes" on the graph), whereas in recurrent fever it lasts for days (wide "trapeziums" on the graph).
Class and exam questions
How does remittent fever differ from continuous fever?
The main difference lies in the amplitude of daily fluctuations. In continuous fever, fluctuations do not exceed 1 °C, whereas in remittent fever they range from 1 to 2 °C, while in both cases the temperature does not drop to normal.
What condition is characterized by an inverted temperature curve?
It is characteristic of severe chronic processes, such as tuberculosis or prolonged sepsis. In this condition, the morning temperature paradoxically exceeds the evening temperature.
What is the graphic difference between relapsing and undulating fever?
In relapsing fever, spikes and drops occur abruptly, forming "blocks" of heat on the chart. In undulating fever, the temperature rises and falls gradually, day by day.
What else to study on this topic
- Mechanism of critical temperature drop
- Period of apyrexia and its clinical significance
- Inversion of the circadian thermoregulation rhythm
- Differential diagnosis of fever curves by graph
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