Sepsis in children is something that we all fear. It is difficult to define and difficult to diagnose early. This millennium has seen a huge rise in the presence of sepsis in education, campaigns and guidelines. I believe that one of the reasons that we're talking about it so much is that we're still trying to understand what we mean. Within that, we are trying to find ways to explain some of the things that we know. That is because a lot of what we know about recognising sepsis is tied up in tacit knowledge.
Tacit knowledge refers to the things that we know but are not easily explained. For example, it is difficult to explain all the elements involved in driving a car. Much of what we do in our lives relies on tacit knowledge. How do you find things? How do you figure things out? These are far easier to do than to explain.
The very nature of the recognition of sepsis makes it something that needs completely taking apart and putting back together.
Sepsis is not easily definable in the first place. 2016 saw the Third International Consensus Definitions for Sepsis and Septic Shock (1). This came from a process that involved two previous attempts to find consensus definitions, a recognition that none of the previous definitions were perfect, and a third brave attempt to find a definition for something that is somewhat amorphous.
The resulting definition: "life-threatening organ dysfunction caused by a dysregulated host response to infection" is a good one and I would agree with it. However, it does little to help us diagnose sepsis in children. Recognising severe sepsis is not a great challenge. Recognising early sepsis in children is very difficult because of the way that children respond to illness.
There is a bit of a misunderstanding that could result from many of the recent guidelines and publications about recognising sepsis in children: that fever plus tachycardia equals sepsis. Since febrile children are routinely tachycardic, this does not make sense. The misunderstanding comes from a retrospective approach to guideline definitions of sepsis. If you look at all the children who were diagnosed as septic, what were the common features at presentation? Abnormal temperature (high or low) and tachycardia come up a lot.
There are two sides to this coin. Sepsis in children is not simple. It is difficult to recognise and thwarted by many biases. Yet it is deadly and anything that we can do to improve our recognition of sepsis is going to save lives. So complexity is no reason for complacency.
Interestingly, there is a paediatric decision tool that
takes into account some of the tacit knowledge features described here. The POPS (Paediatric Observation Priority
Score) includes features such as gut feel alongside physiological values (4). This scoring system is both simple and
over-simple in equal measure. While it
is quick, easy to do and validated, it only gives you a number at the end, not
an answer or a diagnosis. That number
tells you to look at the jigsaw and see what the numbers mean. The higher the number, the harder and longer
you need to look and the better the explanation you need in order to be happy.
References
Tacit knowledge refers to the things that we know but are not easily explained. For example, it is difficult to explain all the elements involved in driving a car. Much of what we do in our lives relies on tacit knowledge. How do you find things? How do you figure things out? These are far easier to do than to explain.
The very nature of the recognition of sepsis makes it something that needs completely taking apart and putting back together.
Sepsis is not easily definable in the first place. 2016 saw the Third International Consensus Definitions for Sepsis and Septic Shock (1). This came from a process that involved two previous attempts to find consensus definitions, a recognition that none of the previous definitions were perfect, and a third brave attempt to find a definition for something that is somewhat amorphous.
The resulting definition: "life-threatening organ dysfunction caused by a dysregulated host response to infection" is a good one and I would agree with it. However, it does little to help us diagnose sepsis in children. Recognising severe sepsis is not a great challenge. Recognising early sepsis in children is very difficult because of the way that children respond to illness.
There are two sides to this coin. Sepsis in children is not simple. It is difficult to recognise and thwarted by many biases. Yet it is deadly and anything that we can do to improve our recognition of sepsis is going to save lives. So complexity is no reason for complacency.
Since we don’t have a retrospectoscope when we see our next
patient, we need to have a good way of recognising possible sepsis and serious
bacterial infection (SBI) amongst the large numbers of children with uncomplicated illnesses. If fever and tachycardia are
not specific, what can we rely on?
Despite hopes to the contrary, routine near patient testing (e.g. CRP) in a primary
care or emergency department setting will not give us the answer.
If neither numbers nor tests can sort the few out from the
many, what is left? Simply put, a global
assessment made by an experienced clinician is what really brings the magic to
the decision making. So what is it that
helps them to make a decision? The
answer is complicated but essentially, they put together a jigsaw of features
and come up with enough of a picture so that the puzzle makes sense. Some of the jigsaw pieces are fairly obvious
but some of them are less well known or involve that tacit element of the process. It is worth being aware of the various factors that influence this crucial decision.
The pieces of a sepsis jigsaw puzzle:
Temperature
Abnormally low or high, infection will affect temperature in
some way. This is an oversimplification
which fails to address some of the subtleties of temperature and its
relationship to bacterial infection and sepsis.
Factors to consider are:
- Low temperature in the context of an unwell child is more indicative of sepsis
- The relationship between height of temperature and sepsis/SBI is loose. Although there is a correlation between very high temperatures and SBI, it is a weak one. Children with viral infections may well get temperatures over 40˚C.
- Temperatures that are more persistent or fail to come down with antipyretics are often seen as more concerning. Again, this is a poor discriminator as this can be seen in viral illnesses. However, it is also true that a child with a persistent temperature may not get the opportunity to demonstrate their wellness by having a little run around.
- A normal temperature at the time of assessment does not rule out sepsis.
Circulation: Heart rate, central capillary refill and
peripheral perfusion
The normality of these factors is quite rightly
reassuring. If outside of a reference
range, these features may or may not be significant. Each of these factors can be affected by
pain, fear, pyrexia and environment.
Again, the extremeness of the abnormality is a consideration as is the persistence
of deranged markers of circulation.
Respiration: Respiratory rate and work of breathing
Abnormal respiration is more discriminatory for SBI and
sepsis, assuming that there is no other reason for being unwell and breathing
abnormally (e.g. viral wheeze). The
reason for this is that respiration is less prone to the physiological changes
that affect circulation. Abnormal
breathing may be caused by acidosis or hypoxia but is less likely to be due to
a simple illness. This ties in nicely
with the definition of sepsis that relates to organ dysfunction. While circulation changes may be a reaction
to an uncomplicated viral illness, respiratory changes are more likely to be
due to organ dysfunction.
Significant episodes
Since we might only see the child for a few minutes, it is
important to take seriously any significant events that have occurred
recently. Pale, floppy or blue episodes
are all notable. Shivering and shaking
are also worth taking into account. They
are not in themselves proof of serious infection. Any of these things can occur during a
temperature spike in an uncomplicated viral illness. Remember that each of these is only a piece
of a jigsaw. You need to look at the
whole picture and if the child is now running around pretending to be Spiderman,
they’re probably OK despite the thing that happened.
Fluid balance
A well hydrated child (wet mucosa etc) who is drinking well
and has good urine output is what you are looking for here. Where these things are not adequate,
sometimes all that is required is analgesia and a fresh start. It all depends on how the rest of the pieces
of the jigsaw are coming together as to whether it is time to go down a
particular path. Dehydration and poor urine output combined with other features is more significant.
Activity, behaviour and interaction
Now we are truly into the area of tacit knowledge. (I wondered when he was getting around to
that...) Very little is published about
the relationship between a child’s ability to smile, play, run or do anything
for that matter and their risk of having SBI or sepsis. However, it is reasonably intuitive that a
child who runs in, smiles and talks the hind leg off of you is less likely to
have sepsis than a child who is carried in, interacts little and looks
miserable. These factors rarely feature
meaningfully because they are impossible to quantify. Each appraisal is as different as each child
is unique. I couldn’t tell you what my
threshold for ‘active’ or ‘interactive’ is because it will be specific to the
child and depends on factors that I could not explain easily. That is tacit knowledge in a nutshell. While no-one can tell you what you are
looking for in this category, it is an important piece of the jigsaw and should
be give the weight it deserves. Your instinct here is vital.
If you use these things in your decision making then that is completely normal. An article in Archives of Disease in Childhood this year (2) published a consensus of which behaviours are seen to indicate that a child does not have sepsis.
If you use these things in your decision making then that is completely normal. An article in Archives of Disease in Childhood this year (2) published a consensus of which behaviours are seen to indicate that a child does not have sepsis.
Parental anxiety
More tacit knowledge here folks. We will ask about symptoms and are looking to
get some fairly specific answers. Much
of what we want to know will feed into the features already mentioned. However, there may be things going on that a
parent will struggle to articulate. It
is our job to distinguish between unwarranted anxiety (“I saw that news story about
the child who died of sepsis…”) and the anxiety that comes from a parent knowing that something is deeply
wrong and being unable to articulate the reason why they know that. The latter is the parent’s own tacit knowledge
being given to you in the form of a person who cannot be reassured.
The trajectory of the illness
I believe that this may be one of the most important yet
least discussed pieces of the jigsaw. No
one has told me about it and it may be that no one has ever told you, but when
I say it, your own tacit knowledge about assessing unwell children will
hopefully agree with the following statement:
An illness that has extreme fluctuation in symptoms (i.e. very unwell
followed by surprisingly well) is almost certainly an uncomplicated viral illness. I am talking about the “you wouldn’t believe
how unwell they looked” kind of illness.
Sepsis and SBI don’t give you time off.
Viral illnesses, it seems, do. So
much so that a child who was floppy and lethargic can within the hour be
smiling, playing drinking and complaining that they don’t want to go home
because they want to play with the toys that you have. It’s not in the guidelines but it is very
important because the opposite is also true.
Two children can have the same heart rate, temperature, hydration and
appearance, but the one who hasn’t had a return to normal in the past few hours
is the one to really worry about in my opinion.
Many of these jigsaw pieces are the more quantifiable and
traditional features that guidelines rely heavily on. The rest are more woolly and difficult to
define, let alone describe. These are
the pieces of the jigsaw that only you, the experienced clinician, can piece
together. If you would like to do a bit more reading about decision making in paediatrics, here is an article published in ADC (open access) (3) which further explores that issue.
The other thing about POPS is that it doesn’t include my
much neglected feature: the trajectory of the illness. I think I’ll make a modified version of POPS
which includes this. I’ll call it
POPcycleS.
How do we disgnose sepsis in children? It remains a clinical diagnosis, best made by someone who has all the pieces of the sepsis jigsaw.
Edward Snelson
Perpetually puzzled physician
@sailordoctor
Disclaimer - If there is a piece of the jigsaw missing, go back and reassess the child. They have probably eaten it.
How do we disgnose sepsis in children? It remains a clinical diagnosis, best made by someone who has all the pieces of the sepsis jigsaw.
Edward Snelson
Perpetually puzzled physician
@sailordoctor
Disclaimer - If there is a piece of the jigsaw missing, go back and reassess the child. They have probably eaten it.
- Singer M, Deutschman CS, Seymour CW, et al. The Third International Consensus Definitions for Sepsis and Septic Shock (Sepsis-3). JAMA. 2016;315(8):801–810. doi:10.1001/jama.2016.0287
- Snelson E, Ramlakhan S Which observed behaviours may reassure physicians that a child is not septic? An international Delphi study Archives of Disease in Childhood 2018;103:864-867
- Roland D, Snelson E ‘So why didn’t you think this baby was ill?’ Decision-making in acute paediatrics Archives of Disease in Childhood - Education and Practice Published Online First: 01 March 2018. doi: 10.1136/archdischild-2017-313199
- Roland D , Lewis G , Fielding P , et al . The paediatric observation priority score: a system to aid detection of serious illness and assist in safe discharge. Open J Emerg Med 2016;4:38–44.doi:10.4236/ojem.2016.42006
