Measurement of Vital Signs

LSU Physician Champion - Dr. Shane Sanne

Measurement of Blood Pressure

Equipment needed: 1. Stethoscope
2. Appropriately sized blood pressure cuff
3. Sphygmomanometer

Step 1: Patient should be relaxed and rested for 5 minutes prior to blood pressure reading with legs uncrossed. All constrictive clothing should be removed (do not role up sleeves above sphygmomanometer as it will potentially cause a tourniquet effect above the cuff). Arm should be at the level of the heart during the reading.

Step 2: Appropriate cuff size is important step to insure the most accurate reading and prevent errors. The cuff should be wrapped around the patient’s bare arm with the index line to help determine if the arm circumference falls within the range. The “ideal” cuff should have a bladder length that is 80% and a width that is at least 40% of arm circumference (a length-to-width ratio of 2:1). The recommended cuff sizes are: For arm circumference of 22 to 26 cm, the cuff should be “small adult” size: 12×22 cm For arm circumference of 27 to 34 cm, the cuff should be “adult” size: 16×30 cm For arm circumference of 35 to 44 cm, the cuff should be “large adult” size: 16×36 cm For arm circumference of 45 to 52 cm, the cuff should be “adult thigh” size: 16×42 cm

Step 3: Blood pressure cuff will be tightly placed so the artery marker on the cuff is located in accordance to the patient’s brachial artery which can be palpated prior.

Step 4: With the patient’s arm in resting position at level of the heart, place the bell of the stethoscope in the antecubital fossa over the brachial artery for auscultation during the reading. The patient or observer should not talk after this point during the measurement.

Step 5: Inflate the cuff until no Korotkoff sounds are heard, typically 30-40mmHg higher above the patient’s baseline blood pressure readings or if unknown baseline then 160-180mmHg with continued inflation until pulse sounds aren’t heard.

Step 6: Begin to deflate the BP cuff while maintaining stethoscope contact at a rate of 2-3 mmHg per second for the most accurate reading.
Systolic reading will be when blood begins to flow through the artery and is the first occurrence of rhythmic sounds.
Diastolic reading will be when the rhythmic sounds stop.

Step 7: For accuracy the test can be taken again in both arms but should done with 5 minutes between each reading.

*Adapted from the AHA Scientific Statement on Recommendations for Blood Pressure Measurement in Humans and Experimental Animals

Measurement of Heart Rate

Step 1: Typically your goal is to assess the heart rate at rest after resting for five minutes. Can check pulse from two locations: carotid artery or radial artery Carotid artery is located adjacent to the trachea using your index and second fingers Radial artery is located at the base of the thumb using the tips of the index and second fingers of the opposite hand.

Step 2: Apply light to moderate pressure with the fingers as above until pulsation is felt. If no pulsation is felt then move the fingers slightly until it is felt. Do not apply excessive pressure as this can compress the artery and distort the pulsations.

Step 3: Using a second hand watch or clock, count the number of beats felt in 30 seconds. Then multiply that number by two to calculate the heart rate in beats per minute (BPM). They should be done on both sides to assess accuracy and symmetry of pulses. Normal readings at rest are 60-100 bpm.

Measurement of Respiratory Rate

Step 1: Your goal is to evaluate the patient’s respiratory rate at rest. The patient should be resting for at least 5 minutes. Have the patient in a comfortable position.

Step 2: Using a second hand watch or clock, count the number of respirations by watching the patient’s rise and fall of the chest as one complete respiration. Instruct the patient to breath normally for them. Count the number of breaths observed in 30 seconds and then multiply them by two to calculate the respiratory rate recorded in breaths per minute (BPM). Normal readings at rest are 12-16 bpm.

Measurement of Temperature

Step 1: There as several options for temperature assessment including: oral, axillary, rectal, tympanic and temporal locations. The last two options would need special attachments or devices for use.

Step 2: Using a covered temperature probe place under the patient’s tongue in the posterior sublingual pocket. For rectal readings use lubricant with gloved hands and carefully insert the probe 1-1.5 inches into the rectum in the direction of the umbilicus. For axillary readings, place the probe under the patient’s arm in the center of the axilla with the arm tightly at the side.

Step 3: Leave the probe at the proper location until the audible sound of the thermometer is heard indicating the temperature has been measured. Normal readings are 97.8 – 99.0 degrees Fahrenheit (F).
Temperatures can vary by location:
Rectally – tend to be 0.5-0.7 degrees F higher than when taken by mouth.
Axillary – tend to be 0.3 - 0.4 degrees F lower than when taken by mouth.

Step 4: Discard the probe cover.