So what's the diagnostic algorithm for sepsis?
Very simply, it all starts with suspected infection.
So your patient has signs or symptoms suggestive of infection.
You're gonna get a qSOFA on them,
and you're gonna wanna know if their qSOFA is greater than two
because that predicts the need for prolonged hospitalization
or bad outcomes.
If the qSOFA is less than two,
you might still suspect sepsis
and the patient might definitely still have an infection
that needs to be treated
so you're gonna just monitor their clinical condition,
provide them with conventional treatment for their infection
just like you would for a non-septic patient
and really kind of keep an eye on things
and see if they develop sepsis over time.
For the patient who does have a high qSOFA,
you wanna be aware that this is a high risk patient,
so these are patients in whom
you're gonna get laboratory studies
that are gonna look for all the types of organ dysfunction
that we discussed in the beginning.
You're gonna wanna check their kidney function,
their liver function,
their blood counts,
all of those kinds of things
to see if they have evidence of evolving organ dysfunction,
and that's gonna allow you to calculate a full SOFA.
If their SOFA is greater than two,
that's when you need to really diagnose them with sepsis
and that's when you're in the realm
of having to treat them aggressively and recognize
that their outcomes are gonna be dependent upon
how effective you are in managing their physiologic derangements.
When do you develop septic shock?
Well, like we said,
if we need vasopressors to maintain an adequate blood pressure,
or if we have elevated serum lactate,
that's when we are in the realm of septic shock
and our morbidity and mortality becomes even higher.
So we just wanna be aware
of the risks associated with septic shock,
and when we do identify them in one of our patients
we wanna be really aggressive about treating them.
So what causes sepsis?
Basically, any infection can do it.
Bacterial, viral, fungal.
Although by far, bacterial are the most common.
There's a number of infection sources
that commonly lead to sepsis.
Lung being the most common,
followed by urinary tract.
And like I said,
the vast majority of these are gonna be bacterial.
Whenever we have a patient in whom we suspect sepsis,
we wanna be really thorough in our history and physical exam
because we wanna get into the bottom line
of what's causing their sepsis
so we can treat it effectively.
What we're really doing is searching for a source.
So we wanna always get a chest x-ray on these patients
to look for the possibility of pulmonary infection.
We wanna get urinalysis
to look for possibility of urinary tract infection.
We always wanna get blood cultures
to identify the subset of patients who are bacteremic.
And we always wanna get a lactate level
because we wanna know
if they are tethering over that border
into septic shock.
Not every patient is gonna have a sepsis source
that is readily apparent on their history
and physical and their basic work-up.
So when we get the test that I just described
and we are still scratching our heads
about why the patient is septic,
we wanna think about moving on to more sophisticated
and or invasive tests.
So we can think about chest or abdominal CT.
Chest CT is much more sensitive for pneumonia
than chest x-ray is
and might be warranted in a septic patient.
Abdominal CTs could help potentially identify
bacterial infections in the abdomen
such as appendicitis, diverticulitis,
or other processes that would merit treatment.
Lumbar puncture is something to consider,
especially if the patient has headache or altered mental status.
And then there are other body fluids
that might need to be sampled.
Patients with liver disease
could have spontaneous bacterial peritonitis
and need a paracentesis
to evaluate the peritoneal fluid as a source of sepsis.
Maybe your patient has pleural effusions
and you need to see if that's actually an empyema.
Maybe they have evidence of aseptic joint
and you wanna know if that could potentially be
the source of their sepsis.
So you need to take the work-up beyond the basics
in order to really rigorously identify
the underlying cause whenever possible.
There are some causes of sepsis that are commonly missed.
Skin infections are notorious,
and I hate to say this,
but especially patients who were unable to give
their own histories and or are debilitated,
a lot of times decubitus ulcers,
cellulitis on the buttocks or back,
it's missed because we simply don’t roll the patient over
after we undress them.
So we need to again,
be thorough and meticulous in our physical exam
to make sure we don’t miss these causes of sepsis.
ENT infections can lead to sepsis and are often missed
again, in patients who are unable to report to you
that they have congestion,
pain in their throat or neck, etc.
Endocarditis is a common source of sepsis.
We always think about it in our injection drug use patients,
but it can also be present sub-acutely
in patients who have other etiologies of bacteremia
such as dental infections.
Intra-abdominal processes can be missed sources of sepsis
and might require advanced imaging to diagnose.
And again, the CNS, is a place where
you can have infection
and the only way you're gonna know about it
is by performing a lumbar puncture.
So you wanna really consider
all the potential sources on the table
and work your patient up appropriately
to identify those sources even the subtle and hard to find ones.
The patients who are unable to give their own histories
because of dementia, stroke, mental retardation,
or just, you know, very young age,
these are the patients who are at highest risk
of having their sepsis sources overlooked.
So whenever you take care of a debilitated patient
or a non verbal patient
who's not able to explain their own history to you,
you wanna be really, really careful
in your search for a source.
Why is this so important?
Well, first and foremost,
there are some sources of sepsis that will need treatment
above and beyond antibiotics.
We all know to give antibiotics to septic patients
and if they have pneumonias or urinary tract infections
that's typically gonna be adequate to control their infection.
However, there are some infections
that require invasive procedures to control.
if you’ve got aseptic joint,
the joint space doesn’t have adequate blood supply
to deliver antibiotics there
so you're gonna need surgical intervention
to drain and wash that joint out if you're gonne cure it.
If you have an intra-abdominal infection,
you might need a surgical procedure
to take care of that source.
So you really wanna make sure
that you know what's causing the sepsis
because you wanna know that you're treating it adequately
and not every cause of sepsis can just be treated
with broad spectrum antibiotics.
So really this is a top priority in sepsis management.
Why do we check lactate?
We all associate that in our minds with sepsis
but what's the physiologic basis for it?
Like we said before,
cellular hypoxia is what really drives shock,
and when the cells are hypoxic at the tissue level
that forces them into an anaerobic metabolic state.
You probably remember from the Kreb cycle
that the by-product of anaerobic metabolism is lactate.
So as you develop tissue hypoxia,
you're gonna develop more and more lactate production
as you force yourselves to make energy using non-aerobic means.
Lactate is a surrogate marker
for the adequacy of tissue perfusion,
so basically, if your tissues are well perfused,
they will be using the aerobic metabolic pathway
and you won't build up much lactate.
Whereas if they are hypoperfused,
they're gonna be forced down the anaerobic pathway
and you will develop lactate.
And this is often the earliest clue
of sepsis in patients who are well-compensated.
So remember I said before,
not every patient in shock is gonna be hypotensive.
If you have a patient with infection
and a significant lactic acidosis,
they might be maintaining their blood pressures
through physiologic compensation,
but that lactate is telling you
that their tissue level perfusion is not adequate,
and you wanna make sure that you address that very aggressively.
So lactate has very good sensitivity
for detection of cellular level hypoxia
but it's only moderately specific for sepsis.
There are a lot of things that can cause lactic acidosis
including simple dehydration.
So not every patient with a high lactate
is gonna be septic
but in the right clinical setting,
where they have infection
and you're concerned about the development of septic shock,
it's a very useful tool
to look at the adequacy of tissue perfusion.