Vital signs are generally the numeric measures of life that typically include a patient’s temperature, heart rate, respiratory rate and blood pressure. In dialysis, however, there are other figures that need to be monitored. Our bodies’ vital signs can be easily observed with the help of different tools. They indicate the current level at which an individual is functioning. The main reason why these signs need to be monitored is basically to establish a baseline before, during, and after a dialysis treatment. A dialysis technician is normally assigned to observe any type of abnormalities in the patient’s body. In turn, this observation will help the nurse and the physician establish the current treatment parameters that will produce the desired effects. In a typical 4-hour treatment, the vital signs of kidney patients are regularly assessed every hour. In some cases, assessments can be done more often depending on the current condition of the patient. Once these numbers are recorded by the dialysis technician, they are compared with normal ranges for the patient’s age and condition.
Vital Signs and the Different Numbers That a Dialysis Technician Monitors:
- Blood Pressure (BP) (Pre-treatment and Post-treatment) – BP is the pressure inside the arteries formed by the pulse wave of each heartbeat. When the heart contracts during a heartbeat, the highest pressure in the artery occurs. When the heart is at rest in between contractions, the lowest pressure sets. A typical BP reading monitors both the highest number (systolic pressure) and the lowest number (diastolic pressure). So, if a patient’s BP reading is 120/80, the systolic pressure is 120 millimeters of mercury (mmHg) and the diastolic pressure is 80 mmHg. Blood pressure is usually measured using a sphygmomanometer. It has an inflatable cuff to restrict blood flow, and a mercury or mechanical manometer to measure the pressure. Both where the dialysis technician puts the cuff and the cuff size can change the accuracy of a BP reading. Cuffs that are too large or wide compared to the patient’s body size will produce a falsely-low reading. On the other hand, cuffs that are too narrow will produce a falsely-high reading. Cuffs that are wrapped too loosely will also produce a falsely-high reading. In kidney patients, alterations in fluid status are the main reason why BP reading rise or fall. As fluid weight rises, the BP also rises. The extra fluid in the blood increases the pressure inside the blood vessels. As fluid weight is removed, the BP goes down, causing the total blood volume to drop as well. So, when a dialysis technician measures the patient’s BP prior to treatment, he should expect to see a higher reading.
- Heart Rate – When the heart beats, its muscles push a wave of blood into the arteries. This wave of blood, or pulse, can be felt or heard at many points on the body. The dialysis technician will learn to measure a patient’s heart rate by feeling or listening at a pulse point. To have an accurate reading, each beat of the heart will be counted in a span of one minute. A normal pulse of an adult is between 60 and 100 beats per minute with regular rhythm. It is very important to tell the nurse about an abnormal pulse rate or rhythm. Where the dialysis technician checks for the pulse: A radial pulse (at the wrist) A brachial pulse(in the crease of the elbow). Anapical pulse(over the heart, using a stethoscope). A pedal pulse(on the foot).
- Temperature – There are different types of thermometers that a dialysis technician can use to measure body temperature. Body temperature is a measure of the body’s ability to generate and get rid of heat. No single temperature reading is “normal” for everyone. For young adults, the average oral temperature is 98.6 degrees Fahrenheit (°F). In older patients, temperature is normally lower, around 96.8°F. In most instances, hemodialysis patients tend to have lower baseline, and pre-dialysis temperatures, for unknown reasons. A high temperature reading before a treatment may indicate a cold or flu, or an infection. When an access, the urinary tract, or a foot is infected, the patient’s body temperature can increase as a result of the body’s biologic response to infection. Inflammation, such as that of the heart, may also cause higher temperatures.
- Blood Flow Rate – During treatment, a blood pump is adjusted to a constant speed to force blood through the dialyzer and back to the patient’s body. The doctor ideally prescribes the blood flow rate, and the dialysis technician sees to it that this rate is maintained. It is also the role of the dialysis technician to let the patient know how much blood is being processed. The blood flow rate is usually set between 300 and 500 mL/min (milliliters per minute). Ultimately, the rate of blood flow is limited by the size of the patient’s access, the tubing, and the needles. Fistulas and grafts normally have better blood flow rates than catheters. To compromise for a slower blood flow rate, patients with catheters may be prescribed a longer treatment and a high flux dialyzer. Higher blood flow rates result to better clearances.
- Dialysate Flow Rate – While this measure plays a minimal role in the determination of clearance efficiency, the rate of dialysate flow impacts the amount of cleaning that happens. Dialysate is the fluid that surrounds the blood compartment of the dialyzer, which acts as an artificial kidney and replaces normal functions of the natural organ. This means that the more dialysate used the more toxins removed from the blood. The dialysate flow rate can be controlled by the machine based on a setting maintained by the dialysis technician.
- Arterial Pressure – Hemodialysis machines monitor the pressure of the patient’s blood inside the tubing and dialyzer. Depending on the machine you’re using, arterial pressure is measured in one of two areas. One is between the patient’s access and the blood pump (pre-pump arterial pressure). The second is between the blood pump and the dialyzer (post-pump arterial pressure). Since the blood pump pulls blood into the tubing, the pre-pump arterial pressure is normally a negative number. Meanwhile, the post-pump pressure is a positive number since the blood pump pushes blood through the arterial chamber. If the pressure is too high or too low, an alarm will go off. This may be due to: Bleeding inside the access arm. Blood clots in the access or needle. Infiltrating needle against the access wall. A kink in the blood tubing. Low blood pressure. Too-rapid or too-sluggish blood pump speed. Separation of the blood tubing from the access of dialyzer.
- Venous Pressure – Venous pressure is the pressure produced between the dialyzer and the patient’s access. If the venous pressure increases from week to week of treatment, it could possibly mean a narrowing of the blood vessels in the patient’s access. If caught early by the dialysis technician, this can be fixed. The venous pressure alarm can sound when: A needle infiltrates the blood vessel wall. The blood tubing kinks. The blood tubing separates from the dialyzer. The blood vessel in the access narrows. The blood pump speed is too fast or too slow. The needle dislodges.
- Ultrafiltration Rate – Removing excess fluid and toxins from the patient’s blood is the one of the functions of dialysis. The process of removing fluid is called ultrafiltration (UF). Since pressure is always higher on the blood side of the dialyzer, fluid moves out of the blood and across the dialyzer membrane. How fast and how much fluid is removed is the ultrafiltration rate. This rate can be adjusted by increasing or decreasing the degree of pressure difference. Modern dialysis machines can typically be set to remove a predetermined volume of fluid from the blood during treatment. The volume is prescribed by the nephrologist based on the patient’s estimated dry weight and actual pretreatment weight. To successfully meet volume removal goals, it is the role of the dialysis technician to make adjustments for the patient’s fluid intake during dialysis. The dialysis technician should also monitor fluid output during treatment, such as urinating or vomiting, for more accurate ultrafiltration rates.
- Volume Removed – Excess fluids can build up in various locations in the body when the kidneys malfunction. This leads to swelling in the feet, ankles and lower legs and/or swelling in the abdomen. Fluid removal is done during dialysis to regulate fluid balance. Most hemodialysis treatments use a prescription for fluid removal targeted to the patient’s dry weight. Dry weight is the patient’s weight without the excess fluid that builds up between dialysis treatments. Clinically, dry weight usually reflects the lowest weight a patient can tolerate without undesirable symptoms, and in the absence of overt fluid overload. The total volume of fluid to be removed is calculated based on the excess of the patient’s dry weight. Ideally, the goal is to target a weight where the patient will be normally hydrated, where he doesn’t feel thirsty, and feel comfortable.
- Trans Membrane Pressure (TMP) – To get rid of excess fluid from the blood via ultrafiltration, a pressure inclination across the membrane is required. In the blood compartment of the dialyzer a positive pressure is produced when the blood is forced through into the narrow fibers. In the dialysate compartment, there is usually a low to negative pressure created by the suction pump in the dialysis machine. The pressure built in between the two compartments, is called the Trans Membrane Pressure. TMP readings are measured and calculated by the dialysis machine. Results may vary depending on machine models. Pressure is provided across the membrane. In order for ultrafiltration to occur, the pressure on the blood side of the dialyzer membrane must exceed the pressure on the dialysate side. This means that the trans membrane pressure should always be positive. The dialysis technician should make sure that this measure is met.
- What the Patient is Doing at Time of Monitor ( Every 30 minutes during treatment) – Dialysis is an effective way to control or reduce the symptoms of chronic kidney disease. Monitoring patient well-being every 30 minutes during treatment is the best way to keep a patient safe during dialysis. Frequent monitoring also ensures that the safety and comfort of the patients are met while they are in the facility. Patients who receive poor treatment may illicit few symptoms acutely. However, in the long run, it can cause high blood urea nitrogen levels, which can decrease the patient’s appetite. Weakness is a sign of inadequate treatment and improper diet.
- Dry Weight (Pre-treatment and Post-treatment) – The majority of dialysis patients make very little to no urine at all. As a result, much of the fluid they drink stays in their bodies in between treatments, making them gain weight. The patient’s pre-treatment weight is used to determine how much fluid weight the patient gained since the last treatment. It is also used to decide how much fluid weight to take off at this treatment. Dry weight is the patient’s weight with no extra fluid and with a normal blood pressure. The nephrologist prescribes the dry weight for each patient. This figure is then used as a basis on how much fluid weight is to be removed during the dialysis. Ideally, the dialysis technician should make sure the patient will be at or near dry weight by the end of a treatment. Removing too much fluid can make the patient feel very ill. Removing too little can also lead to complications like shortness of breath. Since dry weight can change, its accuracy should be monitored closely by the dialysis technician.