Pediatric questions to make you think!

[MediRounds]

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What are the anatomical features of tetralogy of fallot?

 

[OveractiveBrain]

What are the anatomical features of tetralogy of fallot?

First Aid for Step 1

 

[MediRounds]

List them. We want to share with everyone!

 

[Bacchus]

.

 

[NewYorkDoctors]

IIRC

RVH
Right ventricular outflow obstruction
VSD
Overriding aorta

 

[MediRounds]

Finally! Thank you for stepping up! Now that we have that answer, I have a follow up question.

What is the physiology behind a "Tet Spell" and how can it be managed?

 

[Perrotfish]

Why are you making these threads?

 

[MediRounds]

Just doing a little teaching. I thought that it would be a nice topic to discuss.

 

[Internistt]

try cases. that way google wont help.

 

[MediRounds]

I'm getting there...step by step! Thank you. That is a good idea though.

 

[MediRounds]

So...no answers? Ok, there is obstruction of the right ventricular outflow tract (presumably by infundiblar spasm of the muscle below the pulmonary valve or turbulent blood flow going through a small pulmonary valve) which causes shunting of blood from the right ventricle to the left ventricle through the VSD. This causes desaturation with resultant cyanosis because of mixing of oxygenated and deoxygenated blood.

Knowing this, how do you treat a "tet spell"?

 

[VenusinFurs]

Make the RVOT bigger!

EDIT: also propanolol. But I cheated. Also blow-by.

 

[meanlean]

Kidding me!
This is high school stuff or what!

 

[MediRounds]

Sorry. I should have been a little clearer. What is the medical management? If there is a baby in your unit with TOF, how do you treat him/her if the "tet spells" are frequent and significant? Let's say every time the baby cries she/he desaturates to the 50s and is visibly cyanotic. The baby is on oxygen (10 l/m via face mask). What are your medical options? Indulge me, if it's too easy for some of you... 🙂

The baby has one peripheral IV.

 

[J-Rad]

Is this medical-school-Blueprints-Case-Files (etc.) answers or real life answers? I won't give any answers, but the answer affects how interesting the questions can get.

 

[MediRounds]

Real-life answers...based on the patient's physiology. Give it a shot... 🙂

 

[GOMERE]

surgical removal of the muscle....
in the mean time CCB

im just guessing, didnt even cheat and try to google

 

[MediRounds]

Think of how you are going to medically reverse the shunting of blood from left to right through the VSD and how you are going to force blood through the pulmonary outflow tract.

 

[J-Rad]

Real-life answers...based on the patient's physiology. Give it a shot... 🙂

Then I'll try to add some stuff to the questions, although I'd like to make the point that nobody actually knows what the true pathophysiology of a tet spell is in the sense that no one has proven dynamic sub-pulmonary obstruction or infundiblar spasm, etc. That said, your description provides a useful mechanism of understanding the common maneuvers which are tried to abort an episode.

surgical removal of the muscle....
in the mean time CCB

im just guessing, didnt even cheat and try to google

In line with socratic nature of the thread construct here: why do we not use CCBs in neonates? Are there other medicines you might choose to elicit the response you were trying to achieve with a CCB? What response were you going for?

Think of how you are going to medically reverse the shunting of blood from left to right through the VSD and how you are going to force blood through the pulmonary outflow tract.

Just to add some interesting real-life (vice medical student board review) layers to this, let's think about what you will do if your proposed intervention fails. What is your next step?

1. Parents recognize the symptoms of a hypercyanotic episode (how? What anticipatory guidance were they given?). What is their initial step?

2. Parents recognize that their intervention is failing and appropriatley bring the child to the peds ED. What next?

2A. Two of three first steps often written about from a board review persepctive involve administration of some type of drug (though one isn't often thought of as a drug per se). I'd argue that one of those isn't likely to be useful and that the other "classic" first drug has a better alternative. Thoughts?

3. Initial interventions have failed and the patient is becoming more somnolent. What next? Auscultatory examination is noted to have no murmurs, rubs, or gallops and lungs are clear, though the respiratory pattern is unusual with slowish, deep breaths in a see saw pattern.

4. Despite all efforts, the patient continues to appear to be deteriorating. What next? The ED called cardiology and they have been on scene helping to manage this patient. Are there other people you may wish to call?

Questions have been left somewhat vague to allow freedom in answering and to acknowledge that there isn't one way to manage a spell.

 

[MediRounds]

These is a good thought process...anyone want to take a stab at it?

 

[VenusinFurs]

Then I'll try to add some stuff to the questions, although I'd like to make the point that nobody actually knows what the true pathophysiology of a tet spell is in the sense that no one has proven dynamic sub-pulmonary obstruction or infundiblar spasm, etc. That said, your description provides a useful mechanism of understanding the common maneuvers which are tried to abort an episode.



In line with socratic nature of the thread construct here: why do we not use CCBs in neonates? Are there other medicines you might choose to elicit the response you were trying to achieve with a CCB? What response were you going for?



Just to add some interesting real-life (vice medical student board review) layers to this, let's think about what you will do if your proposed intervention fails. What is your next step?

1. Parents recognize the symptoms of a hypercyanotic episode (how? What anticipatory guidance were they given?). What is their initial step?

2. Parents recognize that their intervention is failing and appropriatley bring the child to the peds ED. What next?

2A. Two of three first steps often written about from a board review persepctive involve administration of some type of drug (though one isn't often thought of as a drug per se). I'd argue that one of those isn't likely to be useful and that the other "classic" first drug has a better alternative. Thoughts?

3. Initial interventions have failed and the patient is becoming more somnolent. What next? Auscultatory examination is noted to have no murmurs, rubs, or gallops and lungs are clear, though the respiratory pattern is unusual with slowish, deep breaths in a see saw pattern.

4. Despite all efforts, the patient continues to appear to be deteriorating. What next? The ED called cardiology and they have been on scene helping to manage this patient. Are there other people you may wish to call?

Questions have been left somewhat vague to allow freedom in answering and to acknowledge that there isn't one way to manage a spell.

I will make my best effort here.

1. Parents would be told to watch for the baby becoming cyanotic after a spell of crying/ feeding and becoming limp/ unresponsive. Older kids might compensate by squatting. The baby should be placed on their side in a knee to chest position and comforted.

2. Propanolol/ maybe other beta blockers (?) is indicated in many patients with recurrent tet spells because it can alleviate the subpulmonic infundibular spasm, if this is what is going on in that kid. This would help correct the relative obstruction of the RVOT. In a kid who's in the ED who you are attempting to medically manage, you would want to give them blow by for the cyanosis, maybe some sedation or morphine to keep them from crying. The knee-chest position increases systemic vascular resistance and decreases systemic venous return which would reduce R to L shunting. Phenylephrine increases sytemic vascular resistance, which reducing R to L shunting.

2a. I don't know.

3-4. Kid's going into hypoxic respiratory failure and is losing his/her drive. Needs intubated right now. Because medical management has failed they need a palliative shunt or a complete repair depending on their comorbidities. You've gotta call peds anesthesia and peds surg.

 

[turkeyjerky]

Then I'll try to add some stuff to the questions, although I'd like to make the point that nobody actually knows what the true pathophysiology of a tet spell is in the sense that no one has proven dynamic sub-pulmonary obstruction or infundiblar spasm, etc. That said, your description provides a useful mechanism of understanding the common maneuvers which are tried to abort an episode.



In line with socratic nature of the thread construct here: why do we not use CCBs in neonates? Are there other medicines you might choose to elicit the response you were trying to achieve with a CCB? What response were you going for?



Just to add some interesting real-life (vice medical student board review) layers to this, let's think about what you will do if your proposed intervention fails. What is your next step?

1. Parents recognize the symptoms of a hypercyanotic episode (how? What anticipatory guidance were they given?). What is their initial step?

2. Parents recognize that their intervention is failing and appropriatley bring the child to the peds ED. What next?

2A. Two of three first steps often written about from a board review persepctive involve administration of some type of drug (though one isn't often thought of as a drug per se). I'd argue that one of those isn't likely to be useful and that the other "classic" first drug has a better alternative. Thoughts?

3. Initial interventions have failed and the patient is becoming more somnolent. What next? Auscultatory examination is noted to have no murmurs, rubs, or gallops and lungs are clear, though the respiratory pattern is unusual with slowish, deep breaths in a see saw pattern.

4. Despite all efforts, the patient continues to appear to be deteriorating. What next? The ED called cardiology and they have been on scene helping to manage this patient. Are there other people you may wish to call?

Questions have been left somewhat vague to allow freedom in answering and to acknowledge that there isn't one way to manage a spell.

So do you, uh, want to come back and tell us the answers?

 

[J-Rad]

So do you, uh, want to come back and tell us the answers?

Ugh, I'm sorry. I've been buried at work and life at large hasn't helped. I had an answer up on my computer last week that I never finished and then never submitted.

I will make my best effort here.

1. Parents would be told to watch for the baby becoming cyanotic after a spell of crying/ feeding and becoming limp/ unresponsive. Older kids might compensate by squatting. The baby should be placed on their side in a knee to chest position and comforted.

Doesn't need to be on the side, but otherwise good answer. Mom/dad holding baby upright with knee to chest can also be good if it comforts the child.

2. Propanolol/ maybe other beta blockers (?) is indicated in many patients with recurrent tet spells because it can alleviate the subpulmonic infundibular spasm, if this is what is going on in that kid. This would help correct the relative obstruction of the RVOT. In a kid who's in the ED who you are attempting to medically manage, you would want to give them blow by for the cyanosis, maybe some sedation or morphine to keep them from crying. The knee-chest position increases systemic vascular resistance and decreases systemic venous return which would reduce R to L shunting. Phenylephrine increases sytemic vascular resistance, which reducing R to L shunting.

Great answer!

2a. I don't know.

No, you actually do! Look above, it was in your answer there. The classic med school/boards answer is BBO2 (if they are milder in severity, try not to agitate them with FM or NC) and morphine (calm child, reduce metabolic demand). Phenylepherine is a great drug to increase SVR-it would be one of my next ones in a stepwise approach. Can you think of another sedative known for its increased SVR effect that might make it a better choice than morphine (not such a great drug for people with failing left ventricles)? IF dynamic infundibular spasm is the underlying etiology of tet spells, I'm not sure O2 is really overley beneficial. Pulmonary arterioles respond to O2, but infundibulums? But it makes people feel better.

3-4. Kid's going into hypoxic respiratory failure and is losing his/her drive. Needs intubated right now. Because medical management has failed they need a palliative shunt or a complete repair depending on their comorbidities. You've gotta call peds anesthesia and peds cardiothoracic surg.

Perfect. You're too good. Sedation, inubation and mechanical ventillation may also decrease metabolic demand on this stressed child. And don't call peds surgery, they will not put in a shunt for you 😉 (I know you meant CT surg)

Propranolol in the setting of an active tet spell is controversial, not all think it's a good idea. Kids who have had spells that don't get a shunt may be put on propraolol prophylactically. There are some that advocate a balloon pulmonary valvuloplasty as an intermediary step for relief of obstuction in a progressing spell as well.

I apologize, again, for my delay in responding. I'm glad some people took interest.

 

[J-Rad]

Hopefully our intensivist comes back and lends his perspective as well.

 

[Rendar5]

Hopefully our intensivist comes back and lends his perspective as well.

mind my asking what dose of phenylephrine you use for these kids? I've only used it in adults (for other reasons). Now as for sedation are you referring to ketamine or dexmedetomidine? Never used the latter, though now that you mention it the former seems appealing.

Yes, I've gone from attending to student on this topic. Peds cards scares me because I never feel that I have an intuitive understanding of it when it comes to EM.

 

[J-Rad]

mind my asking what dose of phenylephrine you use for these kids? I've only used it in adults (for other reasons). Now as for sedation are you referring to ketamine or dexmedetomidine? Never used the latter, though now that you mention it the former seems appealing.

Phenylepherine doses (I confess, there are a lot of doses I don't have memorized and look up. From LexiComp, doses for infants/children): IM/SQ-0.1mg/kg/dose q1-2hr, IV bolus: 5-20mcg/kg/dose q10-15min prn, IV infusion: 0.1-0.5mcg/kg/min titrated to effect. I would be using the IV bolus doses in an acute setting.


Yes, I've gone from attending to student on this topic. Peds cards scares me because I never feel that I have an intuitive understanding of it when it comes to EM.

It's hard. Getting into the esoterica (of which there is much) would be of low yield, but I think there are overall concepts that could make people more comfortable (I keep on thinking of writing a review on: the approach to suspected or known CHD in the ED. I haven't found a review that I really like). Here is but one example: knowing all the different defects that may undergo a single ventricle palliation would be a complete waste. But a basic understanding of the single ventricle palliative pathway would lead to understanding of why: kids with Glenn shunts can get as much O2 as you'd like; don't tolerate dehydration well; if they have SVT giving adenosine in an upper extremity is a waste of time. Why kids with Fontans don't have a PE if they're sitting up talking comfortably to you and why the radiologist was wrong in calling it a PE.

Yes, Ketamine is a very good choice.

 

[MediRounds]

Sorry for my absence. Work got the best of me. Anyway, you guys hit most of the important points. The idea is to try and calm the patient for which morphine comes in handy. But, something to notice as well is that infants with TOF are really healthy appearing (meaning that they are not the usual malnourished cardiac child). That is to say as soon as the infant starts to cry and turn blue, the parents pop a bottle into the infants mouth to feed him or her. This usually keeps these kids calm and pink, instead of agitated and blue! Hence, big TOF babies!

The point about manually bringing the knees to the chest in infants will effectively reverse the shunting at the VSD to improve the cyanosis. This trick works in children with unrepaired TOF. The older children can be found squatting to give the same effect as infants, in order to reverse a tet-spell.

Other medical management includes IV fluid boluse, adding propranolol, and eventually intubating the patient. Phenylephine is useful (doses mentioned above). Intubation medications can include ketamine, as mentioned, but fentanyl and midazolam will usually word fine for sedation. What really helps is paralysis.

We recently cared for a "bad" TOF, which required intubation. The patient was on a phenylephrine infusion, but the fluid administration and paralysis seemed to work the best.