Unfortunately, despite advances in modern medicine, no single test can be used to determine if someone has sepsis or not. To confirm a diagnosis, a variety of tests are performed.
The “Sequential [sepsis-related] Organ Failure Assessment” (SOFA) is a mortality prediction score used in the intensive care unit (ICU) based on blood tests and physiological analyses that are routinely measured in sick patients. These tests measure the function or rate of failure in 6 major organ systems: cardiovascular (heart), central nervous system (brain), coagulation (blood), hepatic (liver), renal (kidneys) and respiratory (lungs). Each category is scored on a scale from 0 (normal) to 4 (highly abnormal). SOFA looks for a change of 2 or more points from the patient’s baseline score to help differentiate an infection from sepsis.
The PaO2/FiO2 ratio measures the amount of oxygen that is breathed in compared to how much oxygen is making it into the bloodstream. If a patient has a low ratio, this means that there is not a lot of oxygen being exchanged in the lungs. This is a sign that the respiratory system is not functioning properly. Not enough oxygen in the body is a condition known as hypoxia, or too much carbon dioxide in the body causing what is known as acidosis. If the PaO2/Fio2 ratio is low, oxygen therapy may be required. If a patient’s lungs are failing they will often be mechanically ventilated meaning they will have a large plastic tube down their throat and will consequently be sedated.
Platelets are small components of blood that circulate alongside red and white blood cells. Platelets help with the formation of blood clots by clumping together at the site of the wound and plug the wound to stop it from bleeding. A healthy individual has between 150,000 to 450,000 platelets per 1 microliter of blood. Platelet count has an inverse relationship to the severity of the infection. Therefore, the lower the platelet count, the more severe the infection.
Kidneys are responsible for filtering 120-150 quarts of blood per day, removing waste and excess water through the production of urine. Low levels of urine being excreted is an indication that the kidneys are malfunctioning and not filtering out excess water and waste. Creatinine is a waste product released into the blood by your muscles as a result of using energy. Creatinine gets removed from the blood by the kidneys where it can then be excreted in the urine. When there are high levels of creatinine in the blood, it is an indication that the kidneys are not functioning appropriately as they are not filtering the blood properly. When a patient’s kidneys fail they will often be put on a dialysis machine which mechanically filters the blood for them.
Mean arterial pressure (MAP) describes a patient’s average blood pressure over several heart beats. The systolic and diastolic blood pressures are both used for determining the patient’s MAP. A healthy individual will have a MAP of 60 mmHg or higher. MAP is used to determine the rate of blood flow. The better the blood flow, the higher the MAP and therefore the more oxygen and nutrients are flowing to the vital organs. When a patient’s MAP begins to fall, it means that blood circulation is slowing, this could cause many issues. To combat extremely low blood pressure vasopressors are prescribed to help elevate the blood pressure.
Central Nervous System
The Glasgow Coma Scale (GCS) is a scoring system used to assess the consciousness of a patient. Verbal, eye-opening and motor responses are all rated on the scale. The GCS ranges from 3 (worst) to 15 (best).