Vital Signs: Temperature Measurement and Alterations

• Vital signs are measurements of the body's basic functions.
• Normal vital signs vary with age, sex, weight, exercise tolerance, and overall health.
• The five main vital signs that are usually monitored are body temperature, pulse rate, respiratory rate, blood pressure, and oxygen saturation.

Temperature

• The normal range of body temperature is between 36.7 to 37.2 degrees Celsius.
• To convert Fahrenheit to Celsius: C = (Fahrenheit Temperature - 32) × 5/9

Alterations in Body Temperature

• Pyrexia, or hyperthermia (fever), refers to a body temperature above the usual range.
• Hyperpyrexia is a very high temperature, for example, 41°C (105°F).
• Hypothermia is a core body temperature below the lower limit of normal.
• Frostbite is the freezing of the body's surface areas, such as earlobes, fingers, and toes, in extremely low temperatures.

Types of Thermometers

• Electronic (digital) thermometers are used to measure body temperature.
• Glass (mercury) thermometers are used to measure body temperature.
• Paper thermometers are used to measure body temperature
• Tympanic membrane thermometers are used to measure body temperature
• Non-contact infrared thermometers are used to measure body temperature.

Sites for Assessing Body Temperature

• Oral (common way): 37°C (3–5 min); the thermometer is placed posteriorly into the sublingual pocket and this site tracks changes in core body temperature, as this landmark is close to the sublingual artery.
• Axillary (safe way): 36°C + 0.5°C (10 min); temperature is measured at the axilla by placing the thermometer in the central position and adducting the arm close to the chest wall, and 0.5°C should be added to the actual reading, as this is considered to be an unreliable site for estimating core body temperature because there are no main blood vessels around this area.
• Rectal (accurate reading): 37°C – 0.5°C (2 – 3 min); rectal temperature is the most accurate method used for measuring the core temperature, and 0.5°C should be reduced to the actual reading.
• Tympanic Membrane: a tympanic thermometer senses reflected infrared emissions from the tympanic membrane through a probe placed in the external auditory canal which makes this method quick.

Respiratory Rate

• Inspiration (inhalation) is the act of breathing in.
• Expiration (exhalation) is the act of breathing out.
• The respiratory rate is the number of breaths per minute.
• The normal range of respiratory rate is 12-20 breaths per minute.
• Bradypnea characterizes a respiratory rate of 10 or fewer breaths per minute.
• Tachypnea characterizes a respiratory rate greater than 24 breaths per minute.
• Apnea is the cessation of breathing.

Pulse

• Pulse is a Greek word meaning "move to and fro".
• Arterial pulse is a wave produced by cardiac systole traversing in the peripheral direction in the arterial tree.

Sites of Pulse Examination

• Upper Limb (UL)
• Neck
• Lower Limb (LL)
• Apical Pulse

UL Pulse Sites

• Brachial
• Radial
• Ulnar

Radial Pulse

• It is done with 3 fingers: index, middle, and ring.
• The ring finger should be kept proximal to the heart.
• The index finger should be distal from the heart to obliterate the backflow coming from the ulnar artery, light pressure is given to obliterate.
• Middle finger judges all parameters of pulse.

How To Examine Radial Pulse

• Apply light pressure
• Occlude other arteries
• Palpate for pulse

Brachial Artery

• Rest the patient's arm with the elbow extended, palm up.
• Use the thumb of the opposite hand.
• Cup your hand under the patient's elbow.
• Feel the pulse just medial to the biceps tendon.

The Carotid Artery

• Place the patient lying down with the head of the bed elevated 30 degrees.
• Carotid pulsations may be visible just medial to the sternomastoid.
• Place the left thumb on the right carotid artery in the lower third of the neck at the level of the cricoid cartilage, just inside the medial border of the sternomastoid and press posteriorly.
• Never press both carotids at the same time.

LL Pulsations

• Femoral
• Popliteal
• Anterior Tibial
• Posterior Tibial
• Dorsalis Pedis

Examination of Dorsalis Pedis

• The dorsum of the foot is felt just lateral to the extensor tendon of the big toe.

Comment

• Rate: 60-100 (Normal Adult HR)
• Rhythm
• Force, Tension, Volume
• Character
• Equality on both sides
• Condition of Arterial wall
• Apex Pulse Ratio

Pulse Rate

• Normal adult HR is between 60-100.
• To count, 15 seconds can be timed and multiplied by four to calculate heart rate per minute for a regular pulse
• For an irregular pulse, one should time the pulse for one minute

Pulse Rhythm

• Observation of pulse rhythm gives 3 results:
  • Regularly regular at regular interval
  • Irregular at regular intervals
  • Irregularity is repeated irregularly at irregular intervals

Pulse Volume

• Pulse volume measures the strength or amplitude of force exerted by the ejected blood against the arterial wall with each contraction

Ratings of Pulse Volume

• Weak (thready and usually rapid)
• Normal (full, easily palpable)
• Strong (bounding)