Assessment of Vital Signs

Vital signs are objective measurements of some of the body's essential functions and include temperature, pulse, respiratory rate, blood pressure, and oxygen saturation.

Now, the body's cells need a stable thermal environment in order to maintain basic metabolic processes, so the hypothalamus works like a thermostat to keep the body's core temperature stable. This process, called thermoregulation, balances heat production with heat loss.

To assess your patient's temperature, you'll use a thermometer and measure from one of five sites: the oral cavity, tympanic membrane, temporal artery, axilla, or rectum. The rectum is the most accurate because it closely reflects the body's core temperature but is typically only used when other routes are impractical, like with a very confused patient. In general, you should select a route based on your facility's policies, available equipment, and your patient's needs. A normal temperature is around 37.2 C or 99 F but can vary based on route. For infants and children, normal temperature range can be wider compared to adults because their thermoregulatory mechanisms are less effective.

Okay, moving on to pulse. As the heart pumps blood to the body, the blood causes a pressure wave against the arterial walls called a pulse, which correlates with the heart rate. It can be felt in arteries close to the skin, like the carotid artery, radial artery, or femoral artery; as well as the apex of the heart.

To assess the pulse, you'll use two to three fingers to firmly palpate the artery, being sure not to obliterate it. If the rhythm is regular, count the pulsations for thirty seconds, and then multiply that number by two to calculate the beats per minute. If the rhythm is irregular, count for a full minute. At the same time, assess the amplitude of each pulsation, which is how strong the pulse feels against your fingers.

The pulse rate in adults is typically 60 to 100 beats per minute with a regular rhythm. In infants and children, the rate varies based on age, with the pulse being higher in younger children and gradually decreasing until adulthood. You can grade the amplitude using a scale of 0 to 3+, where 0 is an absent pulse, 1+ is weak and thready, 2+ is normal, and 3+ is full and bounding.

Breathing, also known as respiration, is how the air moves into and out of the lungs. It consists of repetitive cycles of inspiration, which is when air full of oxygen flows into the lungs, and expiration, when the air along with carbon dioxide leaves the lungs.

You can measure your patient's respiratory rate by watching their chest wall movement or by placing one hand on their back to feel their breathing. If their respirations are regular, you'll count for 30 seconds and multiply by two to measure their respiratory rate per minute; but if their respirations are irregular, count for a full minute. Additionally, you'll note the depth of breathing, and the ease of respiration, like if they need to use accessory muscles, such as the muscles between their ribs, to breathe.

The respiratory rate is normally between 12 and 20 breaths per minute in adults. In infants and children, respiratory rates will vary based on age, typically being higher in younger patients. A ratio of 4 to 1, or 4 heartbeats for every 1 respiration can help you anticipate normal values.

Next, blood pressure refers to the force that blood exerts on the walls of the arteries, and it has two values. The first and highest is the systolic, which is the force that blood exerts on the walls of the arteries during systole, or when the heart contracts to pump blood through the body. The second number is the diastolic blood pressure, which is the pressure on the walls of the arteries during diastole, or when the heart relaxes and refills with blood between heart beats. Now, maintaining normal blood pressure is essential to ensure that tissues around the body are receiving an adequate amount of oxygen and nutrients from the blood.

Blood pressure depends on cardiac output, which is the amount of blood the heart pumps in one minute; peripheral vascular resistance, or how constricted the blood vessels are; the elasticity of the vessel walls; the amount of circulating blood; and the viscosity, or thickness, of the blood.

You'll typically take your patient's blood pressure using a stethoscope and blood pressure cuff, called a sphygmomanometer. Be sure to use the proper cuff size to obtain an accurate measurement. Then, position your patient in a comfortable and relaxed position, with their bare arm at heart level and their legs uncrossed.

Blood pressure is recorded in millimeters of mercury, or mmHg. A normal adult systolic blood pressure should be between 90 and 120 mmHg; and a normal adult diastolic blood pressure should be between 80 and 90 mmHg. For children, blood pressure is not typically assessed until 3 years of age and will be lower, the younger your patient, gradually increasing until adulthood.

Lastly, the oxygen saturation in the peripheral tissues, or SpO2, measures the amount of hemoglobin bound to oxygen in arterial blood. It's reported as a percentage and indicates the percentage of oxygen available for the body's tissues.

To measure your patient's SpO2, place the sensor, called a pulse oximeter, on the forehead, ear lobe, or finger or on the appropriate body part according to your facility's policy. A SpO2 of greater than 95 percent is considered normal in patients without lung disease and with a normal hemoglobin level.

Alright, as a quick recap . . . Vital signs are objective measurements of some of the body's essential functions and include temperature, pulse, respiratory rate, blood pressure, and oxygen saturation.