“Management of the Intubated Asthmatic Patient” by Gerhard Wolf and Craig Smallwood
09
October

By Adem Lewis / in , , , , , , , , , , , , , , , , , , , , /


Management of the Intubated Asthmatic Patient
by Dr. Gerhard Wolf and Craig Smallwood. Hi, I’m Gerhard Wolf. I’m an attending in the Division of Critical
Care Medicine in the Department of Anesthesia. My name’s Craig Smallwood, and I’m a Respiratory
Therapist. And today we’re going to talk about how to
ventilate a patient with asthma. Indications for intubation. This is an eight-year-old patient who came
to the hospital intubated and ventilated. He has known asthma. He’s had a couple of asthma attacks before. He’s actually been to the hospital a few times. And today he came to an outside hospital in
status asthmaticus. And he was intubated because the colleagues
there thought he would be in impending respiratory failure. This may be actually a good time to pause
and talk about the indications of intubating a patient with asthma. We typically try to maximize medical management
before we proceed with intubation. Medical management would be continuous albuterol
nebs, maybe the administration of magnesium, a terbutaline infusion, and corticosteroids. And when we see that the medical management
fails, that a patient is getting more tired, has impending respiratory failure, or is in
a position where he cannot protect his airway anymore and he’s obtunded, or he has severe
acidosis that also may lead to him being obtunded, then we typically would think about intubating
him. Initial ventilator settings. So, let’s take a moment and assess this patient. We can look at the monitor. His heart rate is 130. So, it’s quite typical that he’s tachycardic. He’s also gotten a lot of beta-agonists. His blood pressure is normal. His sat is 94% on 40% oxygen. So let’s assess this patient. He’s intubated. He’s still paralyzed; he got a dose of paralytic
during transport. So let’s take a listen. I would say he sounds very tight. There’s really not a lot of good air movement
here. There is very few inspiratory noises and also
very quiet expiratory noises. And surprisingly, I can’t appreciate a lot
of wheezing at the moment. And I think that’s because he’s so obstructed
that I can’t even hear any wheezes. Okay. So could you take us through the steps of
how to set up the ventilator in this patient with asthma? Absolutely. So there’s a couple key components I’m going
to go over. The first one I’m going to do is just mention
secretion clearance. This is one of the simplest to treat an asthmatic. And it’s also one of the most forgotten. Asthmatics, just like most patients who are
intubated, cannot clear their own secretions. So it’s important for us as clinicians to
take on the responsibility. You may be surprised at times as to how much
good you can do by just clearing some mucus plugging or just mucus in general. And that may actually reduce some component
of air resistance you’re seeing on the ventilator. So that means regular suctioning? Yes. In terms of assessing the ventilator, a couple
of basic things. We want to look at the tidal volume and the
compliance of the patient. Right now, our compliance is pretty low. That’s probably due to a mostly resistive
component of the asthma. The pressures we’re using right now to ventilate
this kid are pretty high. We’re using 40/5. And again, that’s just forcing the air past
the airway obstruction that’s associated with asthma. PEEP, Positive End-Expiratory Pressure. For children with asthma who are intubated,
one of the things that we’ll frequently monitor closely is auto-PEEP, or Auto-Positive End-Expiratory
Pressure. Auto-PEEP is a measure of pressure at end
exhalation that describes a difference between the set PEEP and the actual measured end expiratory
PEEP, right before the next breath starts. You can see here on the screen we have two
flow waveforms, one for a child with asthma and one who is exhaling normally. You can see during the blue portion, or the
expiratory phase of the breath, that the flow does not reach zero before the next breath
starts for the child with asthma. This is because the airways are narrowed,
and there is an inappropriately small time for the flow to exit the lungs before the
next breath starts. This will result in an elevated positive end-expiratory
pressure above that which is set. And we describe that as auto-PEEP. Some people call this breath stacking, obstruction,
or auto-PEEP. You should monitor this closely, and try to
adjust your settings appropriately to eliminate as much gas from the lungs during expiration. If we were to look at the pressure waveform
here, you’d see that the PEEP is a little bit beyond that which is set on the ventilator. Compare that with the child who is normal
on the flow waveform who is able to exhale fully, and you can see clearly that the blue
portion, the exhalation portion of the flow waveform, reaches zero long before the next
inspiration begins. To assess that on different ventilators, the
actual way you do that may be different. And I’m going to do an expiratory hold. An expiratory hold is basically just a prolonged
period of time that it’s going to allow the patient just to exhale and measure the pressure
at that point in time. So let’s do that. So right now, our auto-PEEP is 10. Our actual extrinsic PEEP is set at five. So there’s a difference of five that the patient
is actually responsible for due to lung mechanics. So what does the auto-PEEP really tell us? This patient is paralyzed. And what does it tell us? Does it tell us that we don’t want to send
the extrinsic PEEP on the ventilator higher than the auto-PEEP? So PEEP is a little bit of a controversial
issue with asthmatics. Right now, our patient is paralyzed, so one
of the issues is spontaneous breathing, which we don’t necessarily have to worry about. But if he or she was, then what we would want
to do is probably adjust our extrinsic PEEP. That is the ventilator set PEEP to match the
patient’s auto-PEEP. What that does is allow a very small pressure
gradient within the lungs so the patient can trigger the ventilator easily and not have
to use an excessive amount of energy to breathe. So in summary, there’s different ways to think
about PEEP and auto-PEEP in a patient with asthma when he’s intubated, ventilated, and
paralyzed or not paralyzed. In a paralyzed patient, it seems that the
level of extrinsic PEEP that we give should be just lower than the level of auto-PEEP,
or some people would not give PEEP to a patient who is with asthma who is paralyzed at all. If the patient is breathing spontaneously,
then the auto-PEEP becomes pretty important. The level of extrinsic PEEP should pretty
much match the level of auto-PEEP so that the patient can trigger the ventilator. Respiratory rate and expiratory time. So we found the level of PEEP. And what expiratory time or what respiratory
rate do you use? So one of our other goals when treating asthma
is maximizing the amount of time that we’re giving our patients to exhale the breath. With the mechanical ventilator, we can always
force the breath in and help that, but we can’t always force the breath out. So to facilitate breath removal on the expiratory
side of the curve, we like to decrease the respiratory rate. And really what we’re doing is allowing more
time for exhalation to occur. And that is actually quite counterintuitive
most of the times, because the patients with asthma when they’re intubated, they’re typically
hypercarbic. And what often happens is that the level of
carbon dioxide rises. And in reflex, the respiratory rate is increased
in order to increase the minute ventilation. But since they have obstructive physiology,
often that leads to more air trapping, and that the level of CO2 actually rises. So here we have to do the opposite. We have to decrease the respiratory rate,
let the breath fully exhale, and then by this increase the level of CO2 clearance. So how do you know if an expiratory breath
is long enough? Two ways. One, we can assess the auto-PEEP, like we
discussed earlier. The other key component in monitoring asthmatics
on the ventilator is the flow/time graphic. In here, it’s the middle one. You want to pay close attention to the expiratory
phase of that breath. What we want to do is we want to see the flow
come back completely to baseline before the next breath occurs. Now, this might not be necessarily always
possible, depending on the severity of the bronchoconstriction, but you always want to
try to maximize that exhaled breath. So on the flow/time graphic on the expiratory
phase here, in blue on this ventilator, we can see there’s a good peak exhalation flow
here. And then you can kind of see that it kind
of slowly comes back to not quite zero, but there’s still quite a bit of flow in there
before the next breath occurs here. in the red portion of the breath. When you’re decreasing the respiratory rate
or you’re just increasing the amount of time the patient has to exhale, it’s important
to look at the exhalation part of the flow/time graphic. Basically, if the expiratory flow comes back
to zero or comes closer to zero before the next breath occurs, then you’ve done the right
thing. If it didn’t make a difference, then you’re
probably just as fine being at the high respiratory rate. What are typical respiratory rates that you’ve
used in asthmatics? It depends on the patient’s size. So obviously, if they’re smaller, they have
smaller tidal volumes. And therefore, we can get away with a little
bit higher breaths. So a respiratory rate anywhere between 10
or 15 breaths should be actually adequate in this patient, but it really depends on
the expiratory time. Tidal volume. The general mechanical ventilation strategy
for asthmatics employs a high tidal volume and low respiratory rate. Tidal volumes are typically set from 8 to
10 mLs per kilo. Although, in some cases, higher tidal volumes
may be required. The rationale for the higher tidal volume
strategy is simple. Any patient requires a certain minute ventilation. That is the respiratory rate times the tidal
volume in order to maintain adequate gas exchange. And since the respiratory rate has been decreased
in some cases, in order to facilitate emptying of the lungs, the tidal volume must be increased
in order to maintain a reasonable minute ventilation and ensure adequate removal of CO2. Inspiratory pressure. We talked about how you find the PEEP and
how you find the right respiratory rate. What do you do with the inspiratory pressure? How do you find the right inspiratory pressure? So one of the things we like to do is we want
to use the least amount of ventilatory pressure as we can at all times. And asthmatics, because they have such a high
airway resistance, oftentimes we’ll need to use very high levels of PIP, or a high PIP
to force that breath in past the obstruction. In this setup at the moment, the PEEP is 5,
and the delta above PEEP at 35. So the peak inspiratory pressure is 40. We should make an important distinction here
that when we talk about lung protection and minimizing the degree of injury that we impose
on the patient with the mechanical ventilator, we need to talk about plateau pressure. Plateau pressure refers, basically, to the
alveolar pressure in the lungs. And that’s really the pressure we need to
keep at or below 30 centimeters of water. Our PIP, or our Peak Inspiratory Pressure,
may be greater than that, but because the airway resistance is so high, it’s not necessarily
going to be transmitted to the lung periphery. So Craig, can you show us how to measure the
plateau pressure in this patient? To assess that on our patient right now, we’ll
need to do an inspiratory hold. Our peak pressure is 35 plus 5. So that’ll be a peak pressure of 40. That will be the airway pressure in the circuit
around here. Now, the pressure at the alveolus inside of
the patient may be less than that. We’re going to do an inspiratory hold to attain
a plateau pressure to obtain that measure. So here on the pressure/time waveform, you
can see at the beginning of inspiration, we went from 5 of PEEP up to our peak inspiratory
pressure of 40. And then because we allowed enough time and
inspiration for the pressure equilibrate in the whole system– that is the ventilator
circuit and our patient– the pressure actually dropped from about 40 down to 20. Our plateau pressure on this patient is only
20 centimeters of water. The difference between the peak inspiratory
pressure and the plateau pressure is going to be reflective of the airway resistance
that’s part of the patient’s airway disease. So in summary, although we measured a pressure
of 40, a peak inspiratory pressure of 40 on the ventilator, this pressure of 40 may be
actually more of the pressure driven by the resistance of the system. The inspiratory hold maneuver tells us the
plateau pressure. And as Craig said, the plateau pressure is
what the patient is actually receiving. So we’ve done two hold maneuvers. We’ve done an inspiratory hold to determine
the plateau pressure. And we’ve done an expiratory hold to determine
the level of auto-PEEP. Summary. In summary, these are the initial ventilator
settings for the intubated asthmatic. For PEEP, measure auto-PEEP in paralyzed patients
with an expiratory hold, and set the PEEP lower than auto-PEEP. For respiratory rate, allow the patient to
exhale fully, and consider lengthening expiratory time to facilitate alveolar gas emptying at
end expiration. For tidal volume, choose an appropriate tidal
volume, keeping in mind that if respiratory rate is decreased, tidal volume should be
increased to maintain minute ventilation and appropriate gas exchange. And for plateau pressures, the goal, in general,
is to maintain plateau pressures less than or equal to 30 centimeters of water. And this will require using an inspiratory
hold in those subjects eligible to do so. Managing Hypercarbia. Here’s the initial blood gas that we just
got back. The pH is 7.15. The PaCO2 is 75. And the PaO2 is 200. So the patient has no problem with oxygenation,
but he has a fair amount of hypercarbia. So how would we address that? Let’s ventilate more. In an asthmatic, what we want to do is give
more time for exhalation. So I’m going to do two things. I’m going to assess our auto-PEEP right now
to kind of see what our baseline is. I’m going to press the expiratory hold and
see what we get. So right now, our auto-PEEP is 15. Our set ventilator PEEP is 5. So there’s an intrinsic PEEP of this patient
of 10. So I’m going to decrease the respiratory rate. My goal there, Gerhard is going to be to maximize
the amount of exhalation time, hopefully, eliminate a little more alveolar gas, and
ventilate a little bit better. So despite the fact that the patient is actually
hypercarbic, we’re going to go down on the rate in order to let him exhale further and
improve CO2 clearance. So now we went with a rate from 30 to 24. Yeah. And so that has markedly lengthened the expiratory
time. And now we should see the expiratory flow
return to 0 in order for exhalation to be complete. Is that what we find here? Not quite. So, one of the problems with an asthmatic
is you’re probably not ever going to meet a 0 on your expiratory flow, but you’ll get
as close as you can. So right now when we did that maneuver moving
the rate down from 30 to 24, we got a little bit closer on the expiratory waveform. Here is the blue coming back almost to 0 before
the next breath starts. And we can do another expiratory hold here
to assess the amount of auto-PEEP that we have at this rate. So we’ve decreased the auto-PEEP from 15 to
12, indicating to us that we’ve reduced the amount of air trapping. And hopefully, when we get our follow-up blood
gas, we’ve eliminated a little bit more CO2 and allowed our patient to be ventilated better. Hemodynamic Considerations. Another thing I would like to mention in ventilated
patients with asthma are the hemodynamic aspects. Often, patients who are intubated in an asthma
attack or with status asthmaticus have a fair amount of hemodynamic instability. And that comes from a variety of reasons. First of all, these patients may have been
dehydrated, because they have been wheezing for a couple of days at home, and now they
are behind on fluids. Also, they may have a little bit of a pneumonia
going on, or have some septic physiology. Then the amount of acidosis that they have
may negatively impact their myocardium. And also, they may have with their bronchial
obstruction increased pulmonary vascular resistance. So they have elevated pulmonary artery pressures. And that may also impair their overall cardiac
output. Medications. Let’s talk about medical management. The mainstay of therapy here are steroids
and beta-agonists. And so the patient is, at the moment, getting
intravenous steroids. And we will give him beta-agonists as well. And there’s two ways we could give the beta-agonists;
inhaled beta-agonists or intravenous beta-agonists. And usually, the inhaled beta-agonists are
much more effective than the intravenous beta-agonists. So now the patient is intubated. Before he was intubated, he was on continuous
albuterol nebs via inhaler. And now, Craig, are you going to show us how
to give inhaled beta-agonists to this patient? As soon as the patient is intubated, we need
to continue with our bronchodilator therapy. There are a couple of different ways we can
do that. We can do it on the ventilator. We can also take the patient off the ventilator. Right now because our patient is paralyzed,
it’s going to be important for us to maintain manual ventilation while we’re administering
the bronchodilator. Nebulized medications can be given in-line
with the ventilator. It minimizes the disconnects and the time
that the patient is going to be off the ventilator, so possibly preventing an risk of infection
and also hypercapnia. Optimal placement is about 10 centimeters
away from the endotracheal tube. The reason why we put it back here is if placed
after the patient Y, in between the ventilator circuit and the endotracheal tube, we are
going to be increasing the amount of deadspace added to the patient’s circuit, which can
adversely affect efficiency of ventilation. Beta-agonists may be administered every 20
minutes as nebulized therapy with close monitoring for beta 2 related toxicity. A variety of regiments for sedation have been
described in ICU patients. Typically, our patients are on a combination
of both ketamine and midazolam. Ketamine as a sedative drug has the advantage
that it also has bronchodilator properties. We typically use some midazolam in order to
blunt some of the central effects of ketamine with that. One side effect of ketamine may be that the
secretions are increased. So if we run into that, we sometimes have
to stop the ketamine infusion. One of the adjunctive therapies we can consider
in treating asthmatics is the application of heliox gas. It’s a gas that mixes helium and oxygen. It allows a laminar, low-density gas to get
past airway obstruction, and to allow good tidal volumes to be exchanged in and out of
the patient’s lungs. Many ventilators allow you to apply this directly
to the back and automatically do the calculations for you, and setting the heliox in the front
of the ventilator. Some may not. It’ll depend on the equipment you have. The patient who’s going to be most likely
to benefit from heliox is that patient with low O2 requirements. This is going to increase the amount of helium
that can be added into the gas and also the chance that the laminar flow and good tidal
volume exchange will occur. Helium comes in mixtures of either 80% helium
and 20% oxygen or 70% helium and 30% oxygen. So if we hooked up helium to this patient,
we would need to deliver 30% oxygen with the balance being helium. We would therefore want to deliver the helium-oxygen
mixture of 70 to 30. Patients in the range of FiO2 of 0.5 to 0.7
or higher generally won’t respond that well to a heliox administration. Helium administration is therefore really
ideal for patients who do not have a high O2 requirement. It seems important to mention that the helium
in itself can sort of trick the oxygen measurements of some ventilators. That’s why modern ventilators have the ability
to adjust for that. But if you use an older ventilator, that ventilator
may not automatically adjust for helium. And one of the things you may have to do is
put it on an external oxygen analyzer to ensure that you’re measuring the amount of oxygen
that is being delivered to the patient. Heliox in studies hasn’t really shown a clear
benefit, so we don’t really apply it to all the patients, but we sometimes use it in patients
with asthma. What we think is important is to measure the
response. So if you start a patient on heliox, and he’s
doing better, has improved flow, is moving air, his expiratory flow profile looks better
on the ventilator, his blood gas improves, then he is clearly someone who responds to
heliox well. But if we start heliox and really see no change
after six or eight hours, then we stop the therapy and determine that the patient has
not responded. Another therapy that is often discussed is
the use of isoflurane. Isoflurane is a volatile anesthetic. It has very strong bronchodilatory effects. We do use isoflurane in this unit. We have an anesthesia machine set up that
we use to ventilate the patient with isoflurane. But when using isoflurane, it is important
to keep in mind that it has very strong hemodynamic properties. It can cause hypotension. We often have to anticipate that, give volume,
place a central line, start the patient on vasporessors. The use of isoflurane in patients with asthma
is really beyond the scope of this talk. But what we can say about it is that it has
to be used with caution, and it has to be used by centers that have a lot of experience
with it. Weaning. Now it’s 24 hours later, and the patient has
been intubated and ventilated since then. He’s also received his intravenous steroids
and his inhaled beta-agonists. And we just got a blood gas back. And the new gas is now at a pH of 7.25 and
a CO2 of 60 with a PaO2 of 180. So the pH has improved from 7.15 to 7.25 since
yesterday. And the PaCO2 has gone down from 70 to 60. So Craig, what has changed on the ventilator? Sure. So when we’re assessing the asthmatic for
ability to come off the ventilator or separate or decrease the amount of support, one of
the key things we look at is the tidal volume. So since yesterday, his tidal volumes have
increased dramatically. We’re getting about 10 mLs per kilo now. We’re still on the same pressure. So I think what we’re going to do is decrease
the amount of pressure and see where our tidal volumes are. So the tidal volumes have increased, potentially,
because the compliance of the patient has changed. So it’s time to wean. Yes. Let’s take a listen and see what he sounds
like. So in comparison to yesterday, I hear a lot
better air movement. He has actually now inspiratory and expiratory
wheezes, whereas yesterday I could hardly hear anything. And I think that’s probably a function of
the bronchial obstruction getting better. Now, he has air going in and out and I actually
can hear some wheezes, whereas yesterday I couldn’t. So the patient is now wheezing as you would
really expect for a patient with asthma. So, what would we wean? So I just turned down the inspiratory pressure. We’re going to see what our tidal volumes
end up like there. And if our patient continues to improve and
exhibits good spontaneous effort, on this ventilator, the flow waveform and the pressure
waveform here will come up in yellow when the breath is spontaneously triggered by the
patient. If that continues, we can start thinking about
different modes of ventilation. We can transition to pressure support and
allow our patient to do most of the work to breathe. So as the patient got better, we just recently
discontinued the neuromuscular blocking agents. So the patient is no longer paralyzed, and
he’s now breathing spontaneously. We can see that as this ventilator the flow
curves have turned yellow, which means that the breaths are spontaneously triggered. It may look different on other ventilators,
but the patient is now breathing. And we typically– I mean, the patient came
to us paralyzed. And since he was acidotic, we left him paralyzed. But we typically try to get the patient breathing
spontaneously as soon as possible. And can you summarize for us the benefits
of spontaneous breathing in this patient? Sure. So with a positive pressure conventional ventilator
like this, we the clinicians can use the ventilator to force the breath into the patient, but
we can’t always force it out. In many patients, that’s not an issue. With asthmatics, because most of their problem
is exhaling the breath due to airway resistance, they’re going to have a lot of trouble doing
so. When we wake them up and allow them to spontaneously
breathe, they’re going to do two things. They’re going to help the ventilator get the
breath into their lungs. But then they can also use accessory muscles
and intercostal muscles to force the breath out. And this kind of goes back to the auto-PEEP
principle. And if the patient is able to force the breath
out, it’s going to decrease the amount of auto-PEEP, and hopefully get better sooner. Sometimes what we observe is when we go from
paralyzed to unparalyzed, the patients get very tachypneic. Remember, when the patient was paralyzed,
it was no problem to keep him at a low respiratory rate, like 10 or 12, and now that the patient
is no longer paralyzed, he may be more awake and he may be inherently more tachypneic. So his respiratory rate may actually be quite
high in comparison to what he was before. And sometimes that can bring problems, because
now the rate is faster, the expiratory time is shorter, and again, air trapping may increase. So hopefully, the bronchodilators and the
steroids have kicked in long enough that the patient will tolerate being on a faster rate. This can sometimes be such a problem that
we actually have to reparalzye the patient or sedate him more. One of the key questions in a spontaneously
breathing patient with asthma is always the question how to set the PEEP. Because, remember, we can only really measure
the auto-PEEP when the patient is paralyzed. So now that the patient is no longer paralyzed,
we can’t measure the auto-PEEP anymore, because he probably wouldn’t tolerate the expiratory
hold that we would have to do for that. So as a general principle, we can only guess
the auto-PEEP now, but we would want to match the extrinsic PEEP with the auto-PEEP that
we think the patient has. So if we think the patient still has an auto-PEEP
of 6 or 7, then this should be the level of extrinsic PEEP in order to allow the patient
to bring it to trigger. If the auto-PEEP of the patient is eight and
the extrinsic PEEP is only four, and the patient wants to trigger spontaneously, then he would
have to overcome the difference between auto-PEEP and extrinsic PEEP, which would be four in
this case. So that’s what we try to match the extrinsic
PEEP with the auto-PEEP. And so if we think the auto-PEEP is 8, we
would roughly set a PEEP of 8 so the patient can trigger on this PEEP and breathe spontaneously. So our patient has been spontaneously breathing. We’ve been maintaining them in a pressure
control mode. So we’ve been guaranteeing a respiratory rate
of 24. Since our patient is now breathing and we
think the airway resistance is decreasing, and the compliance is good enough, that we
can transition to a spontaneously breathing mode. I’m going to go ahead and transition our patient
to pressure support and see if our patient can tolerate that mode. Extubation Readiness. We just got our blood gas back. And now the pH is actually 7.35. The CO2 has almost normalized to 45. And the oxygenation is still good. So the patient is now in pressure support. So the difference between before, where he
was in SIMV and pressure support and now pressure support is that every breath is pretty much
triggered spontaneously. On this pressure support mode, the patient
will determine his inspiratory time himself. And the level of pressure support is now 15/5. At what point would we think that the patient
is ready to extubate? So here we usually try to decrease the amount
of pressure support to a minimum level and ensure that our patient’s rate, their tidal
volumes, and their oxygen saturation are all adequate. And if those things are maintained, then we’ll
consider taking out the breathing tube at that time. So we think, just roughly speaking, in this
eight-year-old patient, he should have a normal respiratory rate. He should have a fraction of inspired oxygen
no greater than 50. And he should have a pressure support level
of about 6 or 8 above a PEEP of 5. And with that, he should not be tachypneic
and have normal blood gas. And then we could consider waking the patient
up and extubating him. Just listening to him now, he’s still wheezing. And I think that probably won’t change. But when he’s on low settings, I think it
would still be worthwhile to extubate him. So let’s try him on low settings and see how
he’s doing. So we’ve now watched the patient on these
low settings for about an hour. We checked the blood gas, which is okay. And the settings are pressure support 8 over
a PEEP of 5. His respiratory rate is still adequate. He doesn’t need more than 40% oxygen. He’s fully saturated. So I think it’s probably worthwhile waking
him up, and trying to extubate him. That concludes our video on Management of
the Intubated Asthmatic Patient. Please help us improve the content by providing
us with some feedback!


3 thoughts on ““Management of the Intubated Asthmatic Patient” by Gerhard Wolf and Craig Smallwood

  1. I am from Honduras, i am resident in the icu unit, i think your's videos are really helpful sometimes problem is when yo have a obstructive and restrictive pathology such as pneumonia and obstructive component

  2. Very informative videos…open pediatrics is the most reliable aid for pediatrics office practice.. thank you!!

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