These are my notes [which are part of my peripheral brain and help me remember] on Case 3 of Dr. Horeczko’s outstanding podcast and show notes, [Pediatric] Adventures in RSI, November 1, 2015.
And for more on this important but uncommon problem see also Dr. Helman’s outstanding podcasts EMC Episode 84 – Congenital Heart Disease Emergencies and his EMC Best Case Ever 47 – Cyanotic Infant and Congenital Heart Disease Rx – Pre + Post Repair From Dr. Elizabeth Weinstein Posted on August 28, 2016 by Tom Wade MD.
For information on pediatric pulse dose pressors, see Another Great YouTube Video from Dr. Mellick–Pediatric Pulse Dose Pressor Administration Posted on October 2, 2014 by Tom Wade MD.
Case 3 is from 29:10 to 40:35 discusses Cardiac/myocarditis/congenital heart disease.
And we remember that as soon as we realize that we are dealing pediatric cardiac disease, myocarditis or congential heart disease, we want to expedite transfer of the patient to pediatric center that can provide ventricular assist device, complex medical therapy, and even ECMO if needed. If the patient deteriorates in an environment without these capabilities the patient chances will not be maximized.
Jacob is a 6-year-old-boy with tricuspid atresia s/p Fontan procedure who’s had one week of runny nose, cough, and now 2 days of high fever, vomiting, and difficulty breathing.
The Fontan procedure is the last in a series of three palliative procedures in a child with complex cyanotic congenital heart disease with a single-ventricle physiology.
The procedure reroutes venous blood to flow passively into the pulmonary arteries, because the right ventricle has been surgically repurposed to be the systemic pump. The other most common defect with an indication for a Fontan is hypoplastic left heart syndrome.
This is palliative surgery so the goal is to mix venous and arterial circulations to provide a sort of mean arterial saturations.
Every parent will know his or her child’s normal saturation.
Typical “normal” saturations for post-operative CHD can be 75 and 85% on RA. The Fontan procedure improves saturations, which are typically 88-95%.
Complications of the Fontan procedure include heart failure; they come in as cyanotic CHFers and they need hemodynamic support and a gentle diuresis.
Superior vena cava syndrome syndrome can also occur as drainage from the head and neck in these patients is not driven by a pump but is just driven by gravity. Put the head of the bed up. Elevate for fluid overload and evaluate for thrombosus [perhaps with POCUS?].
These children are a setup for a hypercoagulable state. Not only is there a relative venous stasis, but also a lymphatic congestion that alters perfusion to the gut which causes protein-losing enteropathy.
Certain proteins have low turnover times like immunoglobulins or albumin so if we lose them through the cut, we just can’t compensate fast enough.
Other high turnover proteins like the clotting factors will usually keep up. But if there is enough portal venous congestion and hepatopathy, you may see a child with hypercoagulopathy state due to the imbalance between the pro- and anti-coagulant proteins.
Jacob is in respiratory failure. He has markedly increased work of breathing and he [his mental status] is altered. His respiratory rate is 54. His pulse is 140. Blood pressure is 80/60. O2 saturation is 69%.
What is on your differential?
Well, a few things to help us focus:
We know that a Fontan procedure patient can present in cardiogenic shock from heart failure, distributive shock from increased risk of infection, hypovolemic shock from over-diuresis or insensible fluid loss, or just a functional hypovolemia from the fact that venous return is all passive, and finally obstructive shock due to pulmonary thromboembolism.
[We have potentially all the major kinds of shock in these kinds of patients] – In fact, these are how a patient codes: C-O-H-D-E (the E is silent):
- C – Cardiogenic
- O – Obstructive
- H – Hypovolemic
- D – Distributive
So, let’s see what we can do to sort this out. We will use our powers of assessment, intervention, and re-assessment.
We put the ultrasound probe on his heart and he has adequate squeeze. [And] there is no pericardial effusion.
The main thing now is: Should we give fluids?
The overriding principle in children after paliative surgery for cyanotic heart disease is that they are volume dependent. [Emphasis added]
Even if there is a component of cardiogenic shock, they need volume to drive their circuit. They have no pump to do it for them.
So, give 10 ml per kilo of normal saline while we are trying to figure out the rest.
He will likely need a pressor and you should just go with what you know.
Now I need to go on a tangent.
As a huge caveat, we are now wading murky territory here.
Evidence for the pharmacologic management of cardiogenic shock, is, sadly, very scant.
We have to just use our technical knowledge of this patient’s pathophysiology and our theoretical knowledge of what each vasopressor’s unique talent is to guide us.
In adults, the ACC and AHA guidelines recommend norepinephrine (noradrenaline) for marked hypotension in cardiogenic shock–really, because it is so potent and it helps to bring up systemic vascular resistance and it will bring the blood pressure up.
The question is: Are we making the heart pump harder because of an increase in afterload due to the norepinephrine? Really in adults it is a whole other ball game as the etiologies of cardiogenic shock are different.
Correcting the underlying condition, whether that is a fluid overload or in occluded ischemia, that is really the goal. Norepinephrine is really just an adjunct to buttress the blood pressure enough to use a drug like the inotrope dobutamine or the inotrope and venoudilator milrinone.
Children compensate their shock state early by increasing their systemic vascular resistance. If we give something like norepinephrine to them – it’s okay but they are already doing a pretty good job at that and we don’t get much more bang for our buck.
In cardiogenic shock, the heart is a lazy bum. It is just weakly contracting and the cardiac output suffers because of it.
Epinephrine (adrenaline) has marked beta-1 effects and will increase contractility. You also get a little bump in the SVR and heart rate but not enough to preclude its use.
In children it is okay to ask their heart to pump and work harder temporarily until the underlying process is dealth with. You can see how this logic doesn’t necessarily transpose to the older adults’ causes of shock.
Okay, that is just a long way of saying that you just need to think about what your patient is lacking, and match that with the unique talent of the vasopressor.
Norepinephrine is a great drug for peripheral squeeze. It is fantastic in warm shock where the patient has loss of peripheral tone. This is a common adult presentation.
Epinephrine is great at increasing the cardiac output. It is fantastic for cold shock when the patient is already clamped down. This is the most common presentation in pediatric septic shock.
So, you give careful fluids and you titrate up your epinephrine to effect. And you don’t worry about the lactate level when you are using epinephrine (that’s a whole other discussion [and] I’ll just say the password Corey cycle).
Your task at hand now is how can I help to optimize and preoxygenate this child to intubate him as safely as I can given the situation. Remember, you are never going to get his sats up to the 90s. Don’t even try.
I say this because in an otherwise healthy child who does need intubation you really do want to have his oxygen saturations as high as feasible before you intubate.
In this child’s case, if you can get his sats back to his normal of 75 to 85% you’re winning.
What agent to use? Well he (Jacob, Case 3) has a right to left shunt.
You need to preserve and support his systemic vascular resistance. If his SVR drops, the more poorly oxygenated blood will be shunted into his periphery which will promote acidosis and he will further lose his systemic tone. And he will have this downward spiral.
For a child with right-to-left shunting, a good choice is ketamine as it is going to give us some increase in systemic vascular resistance and will have minimal effect on pulmonary vascular resistance.
Etomidate would be alright here but ketamine is actually preferred.
Ketamine has been studied specifically in children with congenital heart disease undergoing cardiac catheterization in both right-to-left and left-to-right physiologies.
Morray et al In Anesthesia and Analgesia in 1984 found no untoward effects [with ketamine] in either population but he suggested its use more strongly in the right-to-left physiology to support SVR
We want to minimize intrathoracic pressures here for two reasons:
- Impeding venous return will result in exaggerated hypertension.
- Impeding venous return will affect oxygen saturation as this child’s oxygen saturations are dependent on good passive venous return.
So use normal to low ventilator pressures. Keep Peep to a minimum and maintain neuromuscular paralysis until stable. This means rocuronium followed by repeat doses or a longer acting maintenance like pancuronium.
What if your crashing patient had a left-to-right shunt as seen in unrepaired ASD or VASD?
Too much SVR may impede forward flow. Even a slight reduction [in SVR] may help.
My take is that there is likely to be a decrease in SVR just by blunting the catecholamine response in the course of RSI.
So, for a left-to-right shunt, known or suspected, let’s go with a neutral drug like etomidate.
In short, a blue baby with right-to-left shunt needs some pinking up with ketamine.
A pink baby, with left to right shunt, is already doing okay. Don’t rock the boat. Give a neutral agent like etomidate.
Now what if another previously healthy baby comes in with predominantly cardiogenic shock as we see in viral myocarditis?
Or, maybe you just don’t know.
I would say if sepsis is your main concern use ketamine.
If you don’t know, use etomidate.
If the child, in hindsight, had more of a sepsis syndrome, and you had given etomidate, you’re still fine. Etomidate is still a perfectly acceptable agent even in sepsis.
The proper logic is if you know it is sepsis ketamine happens to offer a slightly better hemodynamic profile. But there is no evidence of harm with a single dose of etomidate in sepsis. In fact, there is more literature to support its use than to refute it.
So in this child [Jacob, Case 3] with Fontan physiology and right to left shunting, we want to support his SVR and keep him paralyzed.
So what do we give? Ketamine and rocuronium.
Induction Agent in Cardiogenic Shock
A blue baby – with a R –> L shunt – needs some pinking up with ketamine
A pink baby – with a L –> R shunt – is already doing ok – don’t rock the boat – give a neutral agent like etomidate.
Myocarditis or other acquired causes of cardiogenic shock – etomidate. Ketamine is an acceptable alternative, but watch for tachydysrythmias.
At the very end of his podcast, [Pediatric] Adventures in RSI, Dr. Horeczko summarizes the lessons from all four cases:
In summary, in these cases of sepsis, multitrauma, cardiogenic shock, and status epilepticus:
- Resuscitate before you intubate
- Use the agent’s specific properties and talents to your benefit
- Adjust the dose in critically ill patients: decrease the sedative, increase the paralytic
- Have post-intubation care ready: analgesia, sedation, verification, NG/OG/foley