Let's Talk About Sepsis
In my medical ICU, many of the patients are in septic shock because of some type of infection. Have you ever had a patient's family ask you about sepsis? "Why is my family member's blood pressure so low?"
Is there any easy way to explain this to them or do you just say, "their body is reacting abnormally to a widespread infection?"
So this is how I like to explain it. Say that you have a splinter in your finger--what happens to it? It becomes red, hot and infected. Why is it red and hot? The body has opened up the veins around the splinter to let white blood cells out and fight the infection. Just like this, when someone is septic, all of the patient's vessels open up (decreasing the blood pressure) to try and fight the infection. The only problem is that the body is fighting the infection systemically. So what causes this widespread response?
The Mayo Clinic states that "sepsis occurs when chemicals released into the bloodstream to fight the infection trigger inflammatory responses throughout the body. This inflammation can trigger a cascade of changes that can damage multiple organ systems, causing them to fail." Common causes are pneumonia, urinary tract infections, cellulitis, and abdominal infections. Sepsis can be caused by bacteria, viruses, or fungal infections.
The usual presentation for sepsis is tachypnea (increased respiratory rate), tachycardia (increased heart rate), fever, and hypotension (low blood pressures). Patients can also exhibit organ dysfunction if the sepsis becomes severe. Symptoms would show decreased urine output, lactic acidosis, hypoxemia (low oxygen levels), elevated liver enzymes, and an increased white blood cell count. Renal failure causes the decreased urine output as well as electrolyte imbalances. Respiratory failure causes the hypoxemia and lactic acidosis. Lactic acid forms when the body breaks down carbohydrates for energy in times of low oxygen levels. When a patient's oxygen levels are too low, the lactic acid level rises and the patient exhibits a lactic acidosis.
Blood cultures should be drawn prior to starting any antibiotic, antiviral, or antifungal treatment. Doctors will usually start the treatment of a patient with hypotension by giving fluid boluses to increase blood pressure or "fill their tank." Think of it this way, if you take a straw and fill it full of fluid and then put that same amount of fluid into a one inch pipe, what is going to happen? The one inch pipe is going to seem like there is a lot less fluid than the straw. The same concept is seen with low blood pressures. The pressure that the fluid puts on either the straw or the pipe is your blood pressure. The straw is totally full of fluid (normal blood pressure) where the pipe is only a quarter full (low blood pressure due to dilated vessels). Fill up the pipe with more fluid (fluid boluses) and the blood pressure should rise accordingly.
If a fluid challenge does not increase the blood pressure (meaning that the pipe is getting bigger in diameter faster than we can fill it up), patients may need vasopressor therapy to increase blood pressure. This, in essence, takes our one inch pipe and squeezes it back down to the size of a straw.
There are risks associated with these very potent medications. These are administered only in an intensive care unit. In my ICU, the usual first vasopressor of choice is Norepinephrine (Levophed). These must be administered through a central line because of their potency. The patient's blood pressure is monitored every fifteen minutes and the medication is titrated accordingly by the nurses. Patients may also need surgery to remove an infection in the case of an abscess of localized infection. Much of treating sepsis (after antibiotic administration) is symptom management. Treat the fever, the low blood pressure, high heart rate as well as any other symptoms that accompany these.
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