Transcript
Speaker: Welcome to Critical Matters, a sound critical care podcast covering a broad range of topics related to the practice of intensive care medicine.
Speaker: And now, your host, Dr. Sergio Zanotti.
Speaker: In today's episode of Critical Matters, we will discuss the role of noninvasive ventilation and high flow nasal cannula in the management of acute respiratory failure.
Speaker: Our guest is Dr. Pateek Doshi.
Speaker: Dr. Doshi is associate professor in the Department of Emergency Medicine and in the Department of Medicine at the McGovern Medical School, the University of Texas Health Science Center in Houston, Texas.
Speaker: He is also Director of Emergency Critical Care for the Department of Emergency Medicine and Medical Director of the Transplant Intensive Care Unit Division of Critical Care in the Department of Medicine.
Speaker: Dr. Doshi is board certified in internal medicine, emergency medicine, critical care medicine, and neurocritical care.
Speaker: He divides his clinical time between the emergency department and the intensive care unit at the University of Texas Medical Center.
Speaker: Dr. Doshi is an accomplished educator and clinical investigator.
Speaker: He recently published a multi-center clinical trial that evaluated high velocity nasal cannula in the treatment of respiratory failure.
Speaker: Pratik, welcome to Critical Matters.
Speaker: Thank you, Sergio.
Speaker: Thank you for the opportunity to talk to your audience regarding this important topic of non-invasive ventilation.
Speaker: Great.
Speaker: I think that it would probably be a good starting point by defining some basic concepts and terms and make sure that we're all talking with a similar terminology.
Speaker: So why don't we start with non-invasive?
Speaker: Sure.
Speaker: So non-invasive ventilation traditionally refers to your CPAP, BiPAP, or
Speaker: and bilevel.
Speaker: To me bilevel and BiPAP are the same term for this purposes here.
Speaker: And generally when we talk about non-invasive ventilation, what we really are saying is it's mechanical ventilation that's applied without the utilization of endotracheal intubation.
Speaker: So when we talk about CPAP or BiPAP, the primary difference is do you provide a continuous pressure that the patient works against or do you provide a differentiation of a high pressure and a low pressure that will allow for the patient to have high pressure during inspiration and a lower pressure during expiration, otherwise referred to as inspiratory positive airway pressure or expiratory positive airway pressure.
Speaker: And this term traditionally has just referred to this kind of modality.
Speaker: I would argue that at this point in where we are in our clinical matters, high flow nasal cannula is a form of non-invasive ventilation that is greater than just simple oxygen.
Speaker: And I think it should be categorized under the global aspect of non-invasive ventilation.
Speaker: Excellent.
Speaker: I think that the point you make is very good in terms of when we think of levels of intensity, the highest level would be with invasive endotracheal intubation and mechanical ventilation, different modalities amongst mechanical ventilation.
Speaker: And a step down has traditionally been what you referred to as non-invasive ventilation, which includes CPAP, continuous positive airway pressure, and bi-level, as you explained.
Speaker: And now what you're suggesting is that with the advent of high flow nasal cannula into our clinical practice, really for reasons we will discuss a little bit later and for some of the findings in your trial and many other trials should really be part of that whole group of non-invasive ventilation as a part of our momentarium for treating patients with respiratory distress.
Speaker: So you live in both worlds, the emergency department world and in the intensive care world.
Speaker: So I think that a good way to approach this would be to maybe talk first of some ED-centered clinical situations and how you see the role or non-role of non-invasive ventilation in these patients based on most current guidelines from ATS but also from clinical trials such as the one that you have conducted.
Speaker: So why don't we start with the most common, I think,
Speaker: area that we've studied or thought about for non-invasive, which is COPD exacerbations?
Speaker: Sure.
Speaker: I would actually argue that we should start with the idea of CPAP and BiPAP in the emergency department.
Speaker: I think over the last 25 years, those have become very commonly utilized technologies for management of patients with a variety of
Speaker: ideologies of respiratory failure or distress.
Speaker: I think to start off with COPD, I think we have the best evidence for COPD and cardiogenic pulmonary edema in terms of utilization of CPAP or BiPAP in that population.
Speaker: So starting off with COPD, I think there's a few things that we learned from the guidelines and from a practice perspective that are important.
Speaker: When we review the guidelines, the important thing to recognize is
Speaker: It's not a role for CPAP or BiPAP in all COPD exacerbation patients, and that's an important difference change to make.
Speaker: I think patients presenting to the emergency department with an exacerbation of their COPD fall into two distinct categories, one that have hypercapnic respiratory failure associated with the COPD and one that don't have hypercapnic respiratory failure.
Speaker: and from an ed perspective what important recognizes to actually do the analysis for is this chronic acidosis from hypercapnia or is an acute acidosis from the concert arrest by the company c o pd if you look at purely the guidelines you know they define it as ph less than seven point three five uh... but in general what you want to be looking as a level of
Speaker: PCO2 that the patient has and understanding that you will see a decrease in pH of 0.03 for every 10 increase in PCO2.
Speaker: So a patient presenting with a PCO2 of 90 with a pH of 733 may actually be partially compensated patient and may not be the optimal patient for BiPAP or may not be the...
Speaker: slam dunk patient, let me rephrase that for BiPAP, versus someone who comes in with a PCO2 of 60 but has a pH of 725, that's clearly an acute respiratory acidosis patient that we're talking about.
Speaker: And I think that the guidelines and some studies have referred to in those patients, like you mentioned, who have respiratory acidosis, acute on chronic or acute respiratory acidosis, are usually respond better to BiPAP or to non-invasive ventilation.
Speaker: Some people have argued that maybe we should use it in all people with COPD just as
Speaker: to prevent hypercapnia, but it seems that the evidence there is not as robust.
Speaker: Right.
Speaker: I think we've attempted to do that.
Speaker: We don't have great evidence either way.
Speaker: So I don't think it would be incorrect to say or to discuss this with your colleagues to say it would not be incorrect to put everyone on a BiPAP or CPAP, but I think functionally and practically it doesn't make sense to put them at a higher level of therapy than they need.
Speaker: I think a second important point when we talk about this is
Speaker: The CPAP or BiPAP is not therapeutic.
Speaker: It's supportive.
Speaker: So it doesn't take away the need for medical therapy that's required to reverse the bronchoconstriction.
Speaker: That's what's causing the decompensation in this patient.
Speaker: So the role of beta agonists and steroids is unchanged and should be actually aggressively pursued where one of the...
Speaker: errors that I see happening is we place the patient on non-invasive and we forget about what the ideology of their respiratory failure is.
Speaker: In this case, it's bronchoconstriction from the COPD and it's important to make sure that we're being aggressive with that therapy as well.
Speaker: And I think that's a great point.
Speaker: It's a supportive therapy that allows our interventions to really make a difference.
Speaker: Now, with respect to the COPD patient in particular, Prateek,
Speaker: So clearly, the lower the pH, the higher the risk of failure, but it doesn't mean that we shouldn't try.
Speaker: Now, can you give us maybe in terms of your perspective or your practice, if you start treating somebody with COPD exacerbation, you put them on non-invasive ventilation, and what settings would you use and how would you reassess that patient?
Speaker: Great point.
Speaker: So I think the second thing that's another potential pitfall in management of COPD with patients with hypercapnic respiratory failure is...
Speaker: Non-invasive positive pressure ventilation, referring to CPAP or BiPAP, is an escalation therapy.
Speaker: Meaning, you may start off at a low level of 10 over 5, but that's not the end game for these patients.
Speaker: What you're really looking for is the differentiation in the pressures to develop over time.
Speaker: So one of the characteristics that you're monitoring is what is their tidal volume, what is their exhale tidal volume on your BiPAP machine, and that's an important bit.
Speaker: When you first place them on, the traditional starting point is 10 over 5, and I don't think it's incorrect to start at 10 over 5, but the more severe their acidosis, the higher you may want to start them.
Speaker: And you're balancing this against tolerance, right?
Speaker: So starting everyone on 20 over 5 would probably be the best thing to make it a de-escalation therapy, but most of your patients will not tolerate those pressures, and therefore we have to treat it as escalation therapy and give them the opportunity to
Speaker: The other part when you're deciding whether someone should go on non-invasive ventilation, I agree with you, Sergio, that every patient should be given that opportunity.
Speaker: But the biggest thing that you want to be monitoring is their mental status, right?
Speaker: If they're uptunded when they show up with severe hypercapnia, I think that patient should have a much shorter leash towards endotracheal intubation and mechanical ventilation compared to someone who is very tachypneic but alert and awake or even awake, not necessarily alert.
Speaker: And those populations, you will try the non-invasive ventilation with a longer leash to give yourself the opportunity to escalate therapy and to get them to a comfortable place where they have adequate minute ventilation while they're able to tolerate the machine.
Speaker: I think that two very important points that you just touched on Prateek is one is that if somebody is obtundant with COPD, let's say CO2 narcosis, it doesn't mean that they cannot be on non-invasive.
Speaker: It just means that you have to be much more careful in terms of how you're monitoring them and probably like you said, have a much shorter threshold or lower threshold to really escalate that to intubation.
Speaker: And the second point that I think is very important is regardless
Speaker: of how you use and who you're using non-invasive and COPD exacerbations in the acute setting, it requires to be at the bedside, to be evaluating, to be monitoring very constantly, and to be titrating to make sure that you are optimizing their ability to ventilate, but also that you are very aware that if something's not working, you might need to move into intubation.
Speaker: When do you pull the trigger and say, this is not working, and you move to maybe intubating the patient?
Speaker: I think the two commonly accepted criteria for pulling the trigger, quote unquote, and intubating the patient is one is the CO2 narcosis that you talked about.
Speaker: The patient is just not able to maintain their mental status and they're becoming close to comatose or are comatose.
Speaker: and you're concerned that they may not be able to protect their airway if they had emesis or something else happened.
Speaker: The second area that it becomes very commonly utilizes hemodynamic instability.
Speaker: So now you have to understand, going back to the physiology of COPD, these patients are trapping, air trapping significantly.
Speaker: When you put them on positive pressure ventilation and you're escalating their positive pressure, you're further increasing their intrathoracic pressure, at least transiently.
Speaker: And this will impact your ability for preload to get back to the heart and you may cause hypotension.
Speaker: So understanding the physiology of what's happening with this patient, those are the two accepted areas where I say I traditionally pull the trigger.
Speaker: one of the pitfalls that I see is a patient that becomes sleepy during their initial evaluation or initial care and they may be getting sleepy two hours into it or three hours into it and the question really is are they now finally their bronchoconstriction is finally improved and they're able to rest after working so hard for so long or are they truly becoming hypercapnic and this is where I think an emergency physician
Speaker: experience is really key because there are times where getting a blood gas, whether it's a venous gas or arterial gas, is important because if they're becoming tired, they may be becoming tired because they're just finally able to breathe adequately and get some rest after working so hard for a while versus them actually becoming more progressively hypercapnic.
Speaker: All excellent points.
Speaker: Let's move to the other presentation that you had mentioned earlier.
Speaker: So clearly in the patient with an acute COPD exacerbation and hypercapnic acute or acute on chronic respiratory failure, non-invasive would be the first therapy as soon as possible in the emergency department.
Speaker: What about the patient that comes huffing and puffing who can't lay down and seems to be in an acute cardiogenic pulmonary edema?
Speaker: That's another great population that I think is also very well suited for non-invasive ventilation.
Speaker: And let's clarify again, just so that there's not confusion.
Speaker: We started off the podcast by saying non-invasive ventilation should really include CPAP and BiPAP and high flow nasal cannula in today's world.
Speaker: So for the rest of this presentation, CPAP and BiPAP will be referred to as non-invasive positive pressure ventilation.
Speaker: and then we will refer to high flow nasal cannula as such.
Speaker: So I think acute cardiogenic pulmonary edema is very amenable to non-invasive positive pressure ventilation.
Speaker: And again, the same principles apply.
Speaker: It's a supportive measure that buys you time for your medical measures to kick in, right?
Speaker: So it gives you an opportunity to make sure that your medical therapy for preload and afterload reduction have opportunity to work so that the heart can be decompressed.
Speaker: Non-invasive positive pressure ventilation is the fastest way to unload your heart, both from a preload and an afterload perspective.
Speaker: I think it's important that a lot of people get confused.
Speaker: They understand the preload component well, but they don't understand the afterload component.
Speaker: And briefly, it's the decrease in transmural pressure on the LV that's actually resulting in decreasing afterload for these patients.
Speaker: So you're decreasing both of those in the fastest manner possible with non-invasive positive pressure ventilation, and that's where it's effective.
Speaker: And I think that, like you mentioned, both of these diseases or clinical presentations really have very good level of evidence and are strongly recommended by current guidelines to be, where non-invasive ventilation to be utilized.
Speaker: Let me ask you one more disease category, which I think is more in the middle, but I want to hear your thoughts.
Speaker: And then I have another question regarding from an ED standpoint to use of non-invasive.
Speaker: What about asthma patients?
Speaker: Sure.
Speaker: This is a...
Speaker: I live in both worlds and going through training, this was actually one of the more enjoyable components because I think an emergency physician thinks about what do they need to do to get this patient well and then to their appropriate disposition.
Speaker: A critical care physician is looking at what am I going to do for the management of the rest of the care in their intensive care unit prior to leaving the intensive care unit.
Speaker: So asthma fundamentally to me
Speaker: is physiologically very similar to COPD in terms of the bronchoconstriction being the respiratory issue.
Speaker: I'm not going to get into the weeds about how it's reversible and it's, you know, the different cytokines and different inflammatory markers are involved, but functionally,
Speaker: it's a bronchoconstriction that results in air trapping and difficulty for patients to have ventilation.
Speaker: These are younger patients, they're healthier patients, so the hypercapnia is not as prevalent in this population.
Speaker: So I think defining the severity of asthma has been the challenge and that's why evidence has never really shown BiPAP or non-immunicative positive pressure ventilation to be effective in this.
Speaker: It's not because
Speaker: I don't think it's effective.
Speaker: I utilize it in my practice, but I think defining the right population is more difficult in this.
Speaker: So in COPD patients, we said that if they have acute hypercapnic respiratory failure associated with COPD, we have great evidence.
Speaker: That phenotype is easy to define, whereas the phenotype for asthmatics is much more difficult to define as what's considered severe.
Speaker: I actually tried to do a clinical trial looking at this particular question during my training and the challenge was defining that phenotype.
Speaker: And we use peak flows and few people have tried to do that, but it's very difficult to find the right population in that.
Speaker: So my short answer is I think functionally it should be as effective as it is in COPD patients.
Speaker: Practically, if you're an evidence-based practice person, it's going to be very difficult to get appropriate evidence for you to make this a slam dunk recommendation from a guidelines perspective.
Speaker: So clearly, I mean, food for thought and maybe some interesting area to research for some of our listeners who might be interested in clinical trials.
Speaker: I also heard a fatigue and I don't practice in the emergency department so I really live only in the clinical world of the ICU.
Speaker: But a lot of times when I see people in some EDs, I might suggest why don't we use non-invasive.
Speaker: And it sometimes even surprises me why is there not a non-invasive machine in every of the trauma or the shock rooms or the high acuity rooms.
Speaker: whatever your ED is designed, but one of my ED friends said that he believes that we should just place anybody in respiratory distress who looks very severe on non-invasive because if anything, if you're going to intubate them, it's a great pre-oxygenation before intubation and it might give you some time to figure out what needs to be done but also providing oxygen at that level.
Speaker: What are your thoughts on this line?
Speaker: I think that's a great point.
Speaker: I agree with your colleague who said I think everyone may deserve a chance at non-invasive positive pressure ventilation prior to decompensation or improvement.
Speaker: Our pre-hospital colleagues have actually shown this to be a very effective technique, right?
Speaker: We have seen that EMS personnel, all EMS trucks have a CPAP machine on there.
Speaker: trucks, and they utilize this quite frequently in patients that are in respiratory distress to buy that time.
Speaker: So we have a lot of actually very good pre-hospital literature that says that pre-hospital application or early application of CPAP in undifferentiated respiratory failure patients does decrease the amount of intubations that are required.
Speaker: The challenge for an emergency department perspective, again, it goes back to the same pitfalls that we've talked about.
Speaker: This is an escalation therapy, and this doesn't replace the need for close monitoring and understanding the disease process, right?
Speaker: So, for example, hypoxemic respiratory failure from ARDS, from pneumonia, from other causes, you have to understand the...
Speaker: the expected course of the disease if you're expected course of the diseases for days or expected worsening prior to improvement i think the role of non-invasive at that time has to be really questioned to say is that going to be adequate or appropriate because obviously this is not a comfortable therapy and having a mask on someone for twenty four hours forty eight hours or seventy two hours is not a reasonable approach to the care of that patient so i think
Speaker: Understanding what the disease process is, is very valuable in determining what the final disposition or final plan of care would be from a ventilatory perspective.
Speaker: But I think I agree with your colleague that in the early assessment, it's worthwhile to try most patients on non-invasive ventilations.
Speaker: So, and I want to touch on something that you just mentioned, but I think it's very important for our listeners.
Speaker: I often hear debates regarding disposition of patients who are non-invasive, where they should go.
Speaker: And I think that what I'm hearing from you, and I want to hear your thoughts on this, if I got it right, is that it's not the modality of being on BiPAP or CPAP that ultimately determines the amount of attention the patient needs,
Speaker: but it's the underlying process.
Speaker: So if you are in an escalation phase where somebody's acutely ill, they probably deserve to go to an ICU or a high intensity setting.
Speaker: If somebody's using this nocturnally, chronically, it's very different and it might be appropriate for from another location in the hospital.
Speaker: I completely agree with the two examples that you've given, but I think the part that, and having lived in both worlds, I think the challenge from the critical care perspective is we feel that the patient may be in the improvement phase and we're too early in giving them a lower disposition and don't think they need to come to our ICU.
Speaker: I think there are many factors that go into what the approach that your hospital may take.
Speaker: It may be availability of ICU beds.
Speaker: It may be the acuity of patients that you're taking care of.
Speaker: It may be the volume that your emergency department sees.
Speaker: But I think fundamentally what's important to remember is these are all patients with respiratory failure.
Speaker: If you have a patient with COPD and cardiogenic pulmonary edema where we have well-established
Speaker: utilization of non-invasive positive pressure ventilation, we still have to remember that it will take four to six hours for them to medically be adequately treated for their bronchospasm or for their pulmonary edema and unloading of the heart.
Speaker: that if it's within that time window, that patient should probably not go to a lower level of care versus if it's after that time period and the patient has been weaned off non-invasive positive pressure ventilation because the medical therapy has kicked in, then it may be more appropriate for them to go to a lower level of care.
Speaker: But I think this is a constant debate between the two worlds that I live in.
Speaker: And the important thing to recognize is where does the patient fall?
Speaker: And I think the conversation should really be about where does the patient fall in their
Speaker: in their care and what is the ability of your non-ICU setting.
Speaker: I think like you said Pratika, as intensivist, we sometimes underestimate the amount of attention certain patients require on non-invasive.
Speaker: It might be like you said, selling them short in terms of disposition.
Speaker: So why don't we leave the ED, go upstairs and move to the ICU now.
Speaker: Like you said, you live in both worlds.
Speaker: And I would like to touch on a couple of ICU-centered clinical situations and how you see the utilization of non-invasive ventilation in these populations.
Speaker: So you do a lot of work with transplant patients, and one of the traditional groups of patients in which non-invasive has been proposed based on some initial very positive clinical trials was the immunocompromised patient.
Speaker: Do you want to comment on that, Pratik?
Speaker: Sure.
Speaker: So I think, so short answer again, if you look at guidelines, they will say that it's worthwhile trying non-invasive ventilation in an immunocompromised patient with the idea that invasive mechanical ventilation with endotracheal intubation has significant infection risk associated with it and that might be enough to put them over.
Speaker: And if they can salvage them with non-invasive, that might be beneficial.
Speaker: And the initial trial did show that to be the case.
Speaker: But I think what we're learning is phenotyping the patient population is very, very important.
Speaker: Not all immunocompromised patients are created equal.
Speaker: So a patient that has a malignancy and that's the reason for the immunocompromised from chemotherapy
Speaker: it's important to understand what that malignancy is and where they are in their care and what is the goal of their care, right?
Speaker: If the patient has a stage four malignancy and oncologic world is evolving dramatically and we may be able to treat some of these or cure some of these in the near future, but at the present time, if the goal of chemotherapy is palliation,
Speaker: That's where I think non-invasive makes a lot more sense because if they do end up on mechanical ventilation with endotracheal intubation and they're on it for even a short period of time or what we consider short period of time of three or four or five days, they may be deconditioned enough where then there's a discussion of whether they can actually get off the mechanical ventilation with endotracheal intubation.
Speaker: They can actually be extubated.
Speaker: and I think that's where the value of non-invasive is.
Speaker: If you have a solid organ transplant patient who's otherwise doing well from the transplantation perspective and they're immunocompromised because of their immunosuppression and they're developing pneumonia, I think it would not be unreasonable to intubate that patient because once you treat the pneumonia, the patient should do well and should be able to get off the ventilator because they don't have underlying lung disease or other problems that may prevent them from getting off the ventilator.
Speaker: Excellent points.
Speaker: I think that you talked about two areas with immunocompromised.
Speaker: On one hand, a lot of what we try to do with non-invasive is not delay, but prevent people from getting intubation and all the associated risk.
Speaker: So we see that in the COPD population, but in the immunocompromised population, the association of ventilator-associated pneumonias obviously has a much more dramatic impact.
Speaker: So early on,
Speaker: a lot of these patients might benefit from a trial of non-invasive, but also this is a population, the cancer population, where a lot of these patients might have different clinical situations, and that's where you kind of include also the palliative aspect of treatment, and maybe non-invasive would be a better route.
Speaker: Let's talk a little bit.
Speaker: One more point, Sergio, on that.
Speaker: I think one of the things that's really underestimated in this is the importance of joint decision making with the patient and their families.
Speaker: Just like non-invasive gives you an opportunity to get your medical therapy to kick in in COPD and cardiogenic pulmonary edema.
Speaker: in the population, especially with advanced malignancy population, for me, it gives me the opportunity to actually have an in-depth discussion of the patient's condition with the patient and the family and hopefully have the opportunity to have some joint decision-making on what to expect and how to best take care of the patient utilizing patient autonomy.
Speaker: Excellent point.
Speaker: And I've seen some debates regarding the use of non-invasive ventilation in patients who are now past that piliation and truly just in a comfort measure mode.
Speaker: And I think that I've here two sides of the coin, but I do believe that if
Speaker: that one of the things that non-invasive does is alleviates the work of breathing.
Speaker: So if it provides from that respect and it's tolerated and comfort, I don't see why it can't be a tool that we utilize in some of these patients as well.
Speaker: What are your thoughts?
Speaker: I completely agree.
Speaker: I think as long as we understand what we're doing it for.
Speaker: I think a lot of the times the pitfall that occurs is we can't intubate someone because they have a do not intubate
Speaker: order or a wish, we think that we are putting them on non-iniscitant positive pressure ventilation is appropriate in that situation.
Speaker: I think this is mechanical ventilation, no matter whether you do it with endotracheal intubation or whether you do it with a mask.
Speaker: So it's important to really talk about, do they want mechanical ventilation rather than talking about intubation by itself.
Speaker: And if they don't want intubation and mechanical ventilation, then I think the discussion needs to be more appropriate.
Speaker: If you're really struggling, I've given you medical therapy to help you with your dyspnea.
Speaker: This may just make you less dyspneic for a short time.
Speaker: And then if that works, then we can take it off and we can work with that.
Speaker: So I think it's really important to make sure that we are very cognizant of how we're applying the technology.
Speaker: Let's move on to another population in the ICU where I think frequently a non-invasive ventilation is used or perhaps sometimes misused.
Speaker: And that is patients who are mechanical ventilation through an endotracheal tube and are extubated.
Speaker: And I think that there's two big populations of these patients.
Speaker: One population is patients who we extubate and think are going to do well but then get into trouble within 48 hours.
Speaker: and developed acute respiratory failure.
Speaker: And what are your thoughts in that population of using non-invasive ventilation as rescue therapy to try to avoid a re-intubation?
Speaker: I think it's a very, I think it goes back to the, your emergency physician colleagues mentality, and I think intensivists have similar mentalities too, is I think in a patient that met all the criteria for extubation and that you expect it to do well, and for whatever reason runs into trouble, I think non-invasive is the same exact thing.
Speaker: I think it's important to provide them an opportunity
Speaker: to avoid a re-intubation.
Speaker: And hopefully it's due to a mechanism that you can rapidly reverse.
Speaker: If it's due to pulmonary edema that developed because they went from positive pressure ventilation to negative pressure ventilation, hopefully diuresis and preload and afterload reduction may be enough to make them avoid a second intubation.
Speaker: So I think there is a value to attempting non-invasive positive pressure ventilation in these patients to avoid an intubation.
Speaker: But again, I think it falls into the category of a very short leash.
Speaker: to say, is this patient going to make it or are they not going to make it?
Speaker: And then have the ability to rapidly intubate them and provide invasive mechanical ventilation.
Speaker: And I think that when we look at the guidelines and clinical trials, what has been suggested is that when a lot of the intensivists apply
Speaker: non-invasive ventilation for rescue therapy in patients who were just extubated very frequently, what it really leads to is delays in intubation.
Speaker: So they probably, like you said, they keep them on too long.
Speaker: And from that perspective, probably the evidence suggests that we might be harming patients by doing that.
Speaker: Absolutely.
Speaker: And I think it's not uncommon, at least in clinical practice, where we see this happen.
Speaker: You know, we think that the patient is going to do okay on non-invasive positive pressure ventilation.
Speaker: We walk away from the bedside to go take care of someone else who's critically ill.
Speaker: And then we get busy for the next hour, two hours, three hours, and we come back and the patient has vomited.
Speaker: And now you're emergently intubating this patient or a patient is uptunded.
Speaker: And now a procedure that was an urgent procedure becomes an emergent procedure.
Speaker: And we have complications associated with that.
Speaker: What about a second category of patients who we have on mechanical ventilation through an endotracheal tube?
Speaker: We consider them to be high-risk patients either because they have a history of hypercapnia or other risk factors, and we utilize the non-invasive as a ladder or as a step-down kind of process where we extubate to non-invasive.
Speaker: What are your thoughts on using that as part of your weaning strategy?
Speaker: my response is probably going to be very um... draw a significant polarization between the intensivists out there but i'm of the belief that there is no such thing as extubating to non-invasive positive pressure ventilation or extubating to BiPAP as i mentioned
Speaker: both are mechanical ventilation and if someone needs mechanical ventilation then why not keep them on the safest available mechanical ventilation which they're already on rather than saying I'm going to take away the endotracheal tube and then put them on mechanical ventilation with a less stable airway with the idea that I'm going to hopefully be able to get there I think better part of valor and thinking about patient outcomes may be to give them an opportunity to determine if they're going to be well enough to be extubated
Speaker: And if they're not, then to have a proper discussion about what the optimal approach to their care would be.
Speaker: So clearly it sounds like in the world of post-extubation support, the literature is not as supportive as we talked in some initial therapies in the ED like COPD exacerbations and a pulmonary edema.
Speaker: But I think that these are all great points, Prateek.
Speaker: So let's talk a little bit about now of undifferentiated respiratory failure.
Speaker: And really what I wanted to hear from you is for you to tell us a little bit about the clinical trial that you recently published on looking at the role of high velocity nasal cannula or high flow oxygen to nasal cannula and compared to noninvasive ventilation in patients with respiratory failure.
Speaker: Thanks, Sergio.
Speaker: So first I want to start off by the terminology.
Speaker: Just like we started off with terminology for non-invasive ventilation, we differentiate them into non-invasive positive pressure ventilation and high flow nasal cannula.
Speaker: So high flow nasal cannula does not refer to our traditional nasal cannula that are applied to patients with 10 liters of flow or 12 liters of flow.
Speaker: High flow nasal cannula is a newer technology that's evolved dramatically over the last decade.
Speaker: There are two major platforms that are available for high flow nasal cannula and the way they provide the flow and the technology, there are some significant differences.
Speaker: The first is
Speaker: What we refer to most commonly as high flow nasal cannula is made by a company called Fisher and Paykel.
Speaker: They have a large bore nasal cannula that provides flows up to 60 liters per minute and are able to provide 100% FiO2 that's humidified.
Speaker: So it's a heated humidified oxygen through a large bore nasal cannula that can go up to 60 liters per minute.
Speaker: The second technology which is provided by a company called Vapotherm and they've coined the term high velocity nasal insufflation to separate themselves provides again heated humidified high flow but they provide to a small bore nasal cannula which is which is able to provide a flow up to 35 liters per minute or 40 liters per minute but fundamentally their physiology is different because the
Speaker: high-velocity nasal insufflation provides flow through a narrow bore nasal cannula, they create greater vortices in the hypopharynx and potentially provide better dead space washout than the larger bore does.
Speaker: Again, this is from fluid modeling and other studies that are published out there, but fundamentally that's the main difference.
Speaker: In practical perspective, before we get to the practical perspective, from a research perspective, most of the clinical trials until now have been utilizing the Fisher and Paykel platform for there.
Speaker: So the FRAC trial that looked at hypoxemic respiratory failure
Speaker: The post-extubation trials, they've all utilized the Fisher and Paykel device for their high flow nasal cannula.
Speaker: And again, what we see in those clinical trials is they do provide significant oxygenation support, don't really provide a whole lot of ventilatory support or don't provide support to wash out your CO2 in that population.
Speaker: Whereas the theoretical benefit of the high velocity nasal insufflation was providing both oxygenation support as well as ventilatory support.
Speaker: So that's how we came to doing the clinical trial because we, as my emergency medicine side came through on this one and the goal for an emergency physician is, I don't know what the cause of the respiratory failure is.
Speaker: When a patient comes in huffing and puffing, as you described earlier, Sergio, they could have both type one or type two respiratory failure.
Speaker: It takes me time to figure out which one it is.
Speaker: And that's why emergency physicians love non-invasive positive pressure ventilation because it can apply to any of those populations until we sort out.
Speaker: Whereas high-flow nasal cannula until this point, we knew that it provided great support for hypoxic respiratory failure, but not so much for the hypercaptening, and that's why the application was difficult.
Speaker: So I think that an important point to just emphasize, Pratik, is you were talking, before we get into the trial, into the details of what you found and some of the interesting findings, is that the high-velocity nasal insufflation, or the vapotherm, because of how it's designed,
Speaker: theoretically but we also think that we see some of those results in trials like yours provides a dead space washout that can actually assist with ventilation.
Speaker: There's also from what I understand maybe you can expand on this a little bit a positive pressure effect that's very important in terms of oxygenation that is probably why
Speaker: a high velocity nasal cannula gives you more support for hypoxemia than a non-rubedior mass.
Speaker: Can you comment on that?
Speaker: Sure.
Speaker: So both of the platforms with high flow nasal cannula will provide you with a positive pressure that's about three to five centimeters of water.
Speaker: So functionally, if you're putting someone on CPAP of five,
Speaker: is the kind of pressure that you can generate with both of these.
Speaker: The amount of flow that's required to generate that pressure will be different between the technologies.
Speaker: With the Fischer and Paykel device, that might be a flow of 60 liters, whereas with the VapoTherm technology or high velocity in the insufflation, that might be at 35 or 40 liters.
Speaker: So it does provide the three main mechanisms for
Speaker: for functionality or for effectiveness of high flow nasal cannula is uh... small amount of positive pressure the extra thoracic dead space washout which could provide technically up to fifteen percent ventilatory support for a patient uh... improving their
Speaker: respiratory efficiency, and then third, the ability to provide 100% oxygen through the nasal cannula.
Speaker: And I think that, as you alluded at the beginning of the podcast, that's why you believe and many believe that this should be part of our thought box when we say non-invasive ventilation.
Speaker: Agreed.
Speaker: So going forward, so as I mentioned, the previous trials with FRAT and the post-extubation trials were using the FNP device or Fisher & Paykel device.
Speaker: One of the interesting things from an emergency medicine perspective is I have patients with undifferentiated respiratory failure.
Speaker: And because I believe that high-flow nasal cannula has evolved to a point where it's no longer simple oxygen therapy, I think comparison to a simple oxygen therapy doesn't make sense.
Speaker: It really is a comparison to non-invasive positive pressure ventilation to say, is this as effective as non-invasive positive pressure ventilation, or is it just another tool in our armamentarium?
Speaker: So we designed a clinical trial to answer this question, and it was, as Sergio alluded to earlier, it was a multi-center prospective trial that was done at five centers across southeastern United States.
Speaker: Two of them were academic centers, three of them were community centers.
Speaker: And we decided to say that high-flow nasal catinol or high-velocity nasal insufflation in this situation was
Speaker: is another tool in our armamentarium.
Speaker: And as such, we designed a trial that was a non-inferiority trial, not a superiority trial.
Speaker: And I think that's an important differentiation to make.
Speaker: Our goal wasn't to prove that you don't ever need non-invasive positive pressure ventilation.
Speaker: I think that has been proven over 25 years.
Speaker: I think it's a very valuable tool that's in our tool belt, but we now have another tool and we wanted to find a role for this tool and to make a case that
Speaker: high velocity nasal insufflation falls into the non-invasive ventilation category, not in simple oxygen therapy.
Speaker: So we randomized 204 patients to either get non-invasive positive pressure ventilation with BiPAP or to get high velocity nasal insufflation.
Speaker: And these were patients that presented to the emergency department in acute respiratory failure that the bedside clinician felt they would have put on non-invasive positive pressure ventilation otherwise.
Speaker: So it's a mix of our traditional patient populations of COPD exacerbations and cardiogenic pulmonary edema, but also some patients that were undifferentiated hypoxic respiratory failure that were involved in this clinical trial.
Speaker: So 65 of these patients were COPD exacerbations, 45 were CHF exacerbation or cardiogenic pulmonary edema patients, and the remainders were a combination of those.
Speaker: So what were the primary endpoint?
Speaker: So the primary endpoint in the ideal world, what I wanted the primary endpoint to be was the rate of intubation.
Speaker: But to be able to answer that question well, if you randomized to one therapy, you should not be able to cross over to the other to actually figure out what the true intubation rate is.
Speaker: but clearly patient care and patient outcome comes first.
Speaker: So from the safety perspective, we actually allowed a crossover in there.
Speaker: So we had a co-primary or primary endpoint was failure of therapy, which was defined as either requirement of endotracheal intubation with mechanical ventilation or crossover to the other therapy.
Speaker: And when we look at that,
Speaker: For the endpoint of endotracheal intubation of mechanical ventilation, actually in high velocity nasal insufflation group, we had 7% intubation rate versus 13% intubation rate in non-invasive positive pressure ventilation, which goes along with the historical data.
Speaker: However, on the crossover rate, there was a greater percentage of crossover, 26% crossover in the high velocity nasal insufflation group versus 17% in the non-invasive positive pressure ventilation group.
Speaker: So I think the important lesson here is we're not saying high-velocity nasal insufflation is superior to non-invasive positive pressure ventilation.
Speaker: What we're saying is it's another tool of non-invasive ventilation that may be applied to undifferentiated respiratory failure patients to determine whether we can salvage them to avoid intubation or to at least give us time to get medical therapy to kick in or may benefit from non-invasive on top of that, non-invasive positive pressure ventilation on top of that.
Speaker: Can you comment, Pratik, specifically to the trial on any interesting findings in specific groups?
Speaker: I know we're now dicing into the data, but I think that's always interesting from a clinical but also investigator's standpoint.
Speaker: Sure.
Speaker: I think there were three most important findings that were interesting.
Speaker: The first was...
Speaker: First question that has not been answered in the generic high-flow nasal cannula population is, what is the effect of PCO2 on... What is going to be the effect of the high-flow nasal cannula or high-velocity nasal insufflation on PCO2?
Speaker: Because that's not been well-defined.
Speaker: The previous literature all said that it had no effect on PCO2.
Speaker: In our trial, actually, if you look at all patients or patients that were hypercapnic to begin with, which was defined as PCO2 greater than 45,
Speaker: all patients improved their pCO2 over time in high velocity nasal encephalation group and the slope of correction was actually the same as the slope of correction for non-invasive positive pressure ventilation which i thought was very interesting and surprising that's not something probably that without knowledge a priori i would have predicted right and that's part of the reason why we did the trial was we wanted to show that and show that it can work in undifferentiated respiratory failure
Speaker: The second interesting finding comes down to the application of this high velocity nasal insufflation of cardiogenic pulmonary edema.
Speaker: As we spent a lot of time earlier talking about non-invasive positive pressure ventilation in cardiogenic pulmonary edema, it's the fastest way to unload a heart and to decrease your preload and afterload.
Speaker: And that's accomplished by maximizing your inspiratory and expiratory pressures and maximizing your intrathoracic pressures.
Speaker: So fundamentally, that's how non-invasive positive pressure ventilation works in cardiogenic pulmonary edema.
Speaker: High velocity nasal insufflation or another form of high flow nasal canada should not really work that well because we said they only provide a pressure of 3 to 5 centimeters of water in the airways.
Speaker: But in our trial, again, 45 patients randomized to 9 basis of positive pressure ventilation or high velocity nasal insufflation, we had zero intubations out of those 45 patients.
Speaker: and only one person was crossed over from high velocity as an insufflation to to BiPAP or 9-invasive positive pressure ventilation.
Speaker: So to me it raises a significant question.
Speaker: Is it one that the amount of pressure that we're putting these patients on is not necessary and maybe all you need is a little bit of pressure, three to five centimeters of water?
Speaker: Or is the role of extrothoracic dead space and improved respiratory efficiency
Speaker: with that three to five centimeters of water enough to salvage a lot of these patients with cardiogenic primary edema?
Speaker: Or is there a mechanism out there that we haven't thought about yet?
Speaker: Those are all great points.
Speaker: And I think that it also illustrates, I mean, that when we do clinical trials, there's always a primary endpoint, but there's a lot that we learn.
Speaker: And at the end of the day, maybe it just generates more questions than giving us all the right answers.
Speaker: So as we get to the final stretch, Pratik, just a couple of questions, or if you want to give us
Speaker: Obviously, you have a lot of experience both in the ED and the IC using non-invasive in all its modalities.
Speaker: But if there are any specific practical pointers that you want to share with our audience.
Speaker: So I think three practical points that I want to make sure, and I presented them as pitfalls earlier.
Speaker: Non-invasive positive pressure ventilation is a supportive therapy to get your medical therapy to fix the underlying pathophysiology of the disease process, right?
Speaker: Whether that's bronchospasm in COPD or asthma patients or whether that's preload and afterload in cardiogenic pulmonary edema patients or figuring out what the hypoxic respiratory failure is due to whether it's ARDS or pneumonia.
Speaker: So it's a supportive measure, not a therapeutic measure.
Speaker: The second point is it's an escalation therapy.
Speaker: it requires bedside assessment and monitoring until some level of stability is achieved.
Speaker: And sometimes that can happen within 15 minutes and sometimes it might take two hours to get to that point, but it is an escalation therapy and therefore it's important to make sure you have close monitoring going on
Speaker: as well as the ability to intervene with endotracheal intubation if that's required.
Speaker: And the last point I want to take away from this podcast is high flow nasal cannula has improved over the last decade to a point where I think it should be considered a modality of non-invasive ventilation, not simple oxygen therapy.
Speaker: And depending on how you want to interpret the literature out there, I think there may be a value to increased integration of high flow nasal cannula, especially because high flow nasal cannula is the opposite of non-invisit positive pressure ventilation, and that's a de-escalation therapy.
Speaker: You can put them on maximal support to start off with, and if you achieve stability, then you can slowly de-escalate, and it might require less monitoring early on because you've maximized their therapy.
Speaker: And if they respond to it, then you can actually wean down rather than in non-invisive positive pressure ventilation, which is an escalation therapy.
Speaker: It might take you longer to get to that stability and appropriate amount of therapy.
Speaker: And I think that all those points are extremely valuable and actionable.
Speaker: I think that when I reflect on my own practice, I know that the incorporation of high velocity or high flow oxygen through nasal cannula has become much more prevalent in my practice.
Speaker: And I also find that patients find it much more tolerable and comfortable than sometimes using different types of masks for non-invasive positive pressure ventilation.
Speaker: So one of the things that we like to do, Prateek, in critical matters is to tap into the wisdom of our guest and talk about a couple of things that are outside of the realm of medicine.
Speaker: Would that be okay?
Speaker: That would be fine.
Speaker: Excellent.
Speaker: So the first question I have for you, Prateek, is what book or books have influenced you the most or what book have you gifted most often to others?
Speaker: That's an interesting question.
Speaker: I think the book that has impacted me the most or what I would describe as my favorite book of all time is called The Alchemist by Paolo Coelho.
Speaker: It's a short book, it's 180 pages, but it's one of those books that teach you the importance of living your life to a goal, to actually have a personal legend, to be passionate about your life.
Speaker: And it's a book that I've probably read a dozen times.
Speaker: And every time I'm feeling that I'm burnt out or I'm feeling that the world is not working out the way it should, I read the book and it reminds me that I have my own things to do and the world will kind of work with me as long as I'm passionate about it.
Speaker: Absolutely.
Speaker: And I think that it speaks very highly to that whole concept of living by design and not by default.
Speaker: So really thinking about why are we here and what can we do to make it worthwhile?
Speaker: So, you'll find the book linked in our show notes and also the clinical trial Dr. Doshi has been the lead author on and other references.
Speaker: So, my second question, Pateek, is what do you believe to be true in medicine or in life that most others don't believe?
Speaker: you're really challenging me here.
Speaker: I think one of the biggest tenets or one of the most challenging things in our society and I think it applies to medicine as well is a lot of people define the quality of a decision by the outcome.
Speaker: And I think the quality of decision has nothing to do with the outcome.
Speaker: The quality of decision has everything to do with the information available to you when you make the decision.
Speaker: So for example in life,
Speaker: You know, sometimes you do the right thing and things don't work out.
Speaker: And I think we accept that to some degree, but still think that the decision was wrong.
Speaker: In medicine, I can give you a better example.
Speaker: I feel that when we as quality movement in health care has become more prevalent and as we're finally recognizing that we're not perfect, I think one of the challenges that I face is when patient outcome is fine,
Speaker: We always think that whatever we did was right, even though we can actually go back and determine that some of the decisions were not optimal, right?
Speaker: We talked about pitfalls a variety of times during our talk.
Speaker: Despite those pitfalls, patients do okay and we think everything was fine.
Speaker: Whereas when a patient does poorly, everyone is out to figure out what we did wrong.
Speaker: And there are times where we could have done everything perfectly well and the patient just didn't do well and that's okay.
Speaker: So I think the point of this is
Speaker: It's important to understand that there's a right decision with the information available to you.
Speaker: And if you make the right decisions, more often than not, you will come out ahead.
Speaker: And in healthcare, if you make the right decisions, more often than not, your patients will do well.
Speaker: But it doesn't mean that if they don't do well, that you did something that was not the best decision.
Speaker: And I think it's true.
Speaker: I think that it speaks very highly to the whole idea that what are the things that we can control and the things that we cannot control.
Speaker: Right.
Speaker: And outcome, a lot of times, something that is out of our control.
Speaker: Exactly.
Speaker: The final question would be, is there something, what would be something you want every intensivist to know?
Speaker: Could be a quote or a fact.
Speaker: What all my residents will say, and I think this is appropriate, is the quote that I live by is, your eyes cannot see what your mind does not know.
Speaker: And I think that's really important to understand because our growth in medicine has to continue for the rest of our careers and probably the rest of our lives.
Speaker: Because we will never know everything about everything, but something that you don't know, you will never see.
Speaker: Whereas things that you know, you may be able to identify when you see them.
Speaker: So I think your eyes cannot see what your mind does not know is an important
Speaker: tenet that I at least live my life by, and I think it's an important one.
Speaker: And I think it's a beautiful place to stop.
Speaker: Prateek, thank you so much for your time.
Speaker: I think that we had a very interesting discussion on a very important and relevant topic that touches our practices really on a daily basis.
Speaker: So again, thanks for being so gracious with your time and your knowledge.
Speaker: I hope to have you back in Critical Matters.
Speaker: Thank you, Sergio, for the opportunity, and thank you, audience, for having me here today.
Speaker: Thanks again for listening to Critical Matters.
Speaker: Make sure to subscribe to this podcast on iTunes or Google Play.
