Saturday, November 29, 2014

Oxygen: Savior or Devil in a Green Dress?

Prepared by Michael. C Berrier, NRP, FP-C, C-NPT, AAS
Reviewed by: Yen Chow, MD 
                    


If you ask any small child what doctors do or what happens in a hospital, you’ll probably get some variation of “they make sick people better.” Were you to ask the same question of one of those doctors or someone working inside the hospital, you’d likely get a more complicated, wordy and educated version of the same answer. We all tend to believe that our goal is to improve our patient’s health and, truly, make them better. However, that isn’t true at all. The human body is an impressive machine which needs little improvement from the likes of us in order to function. Our goal as end users is to maintain our own body with diet and exercise, but its original design is pretty fantastic. 

This version of a human being works best by following several basic physiological rules:

*We eat our food (enteral nutrition)
*We circulate our blood through normal vessels (Heart beating, stroke volume,     drug free)
*We breathe our air (negative pressure ventilation, 21% oxygen)
*We do all of this without tubes, lines and wires. (No ET tubes, no trach, no         foley, no NG)

The human body is, however, fragile and prone to breakdown, usually through neglect and misuse (see diet and exercise again). This is where medicine comes in, not to make people better but to help return them to the best working version of themselves.

Modern medicine is often about adding and taking away to achieve this goal. We add drugs, we take away excess fluid. We add positive pressure, we take away afterload. This is the kind of physiological arithmetic that a well body will do for itself, but the unwell machine cannot or will not. And while the interventions by which we do this medical math are lifesaving in the short term, in the long run they are at worst harmful and at best contrary to our stated goal of returning to the model of humankind. If we stop eating, out gut will stop working. Too many drugs (recreational or otherwise) will cause permanent damage and remodeling to our heart and vessels. Positive pressure ventilation for as little as 18 hour will cause diaphragmatic atrophy, and tubes left in too long can lead to things like infection, stenosis and tracheomalacia.

But, probably the most commonly used medical interventions by providers from first aid to anesthesia is supplemental oxygen. One of the very first things I learned in basic EMT school was how to operate an oxygen system to provide oxygen to…everybody. No patient was spared the healing wonder of compressed gases. After all, if they’re sick enough to need an ambulance, they must be sick enough to need the green skinned breath of life carried within. Even as I progressed through EMT-Intermediate and paramedic schools, the mantra for nearly every patient began with “IV, O2, Monitor”. 



And it is true, for a very specific patient population, supplemental oxygen can be the difference between life and death. Unfortunately, that population is a good bit smaller than we have been led to believe. Even the patients who will benefit from oxygen concentrations above atmospheric would benefit from another treatment even more, such as CPAP or inhaled bronchodilators or suction. The truth is that, unless your patient hails from a planet where the atmosphere is made up of more than 21% oxygen, applying more than that does not fix a problem, it only treats a symptom. Based on the evidence, in the absence of hypoxia, supplemental oxygen seems to do no good and may in fact do harm to patients with a variety of acute illnesses and injuries.


Science & History: The presence of oxygen in the atmosphere has been studied and well understood for centuries, and the ancient Greeks had an understanding that air was vital to life. However, the role of oxygen in body metabolism has been well documented and understood for only a little over a century. The first account of continuous oxygen therapy for a specific illness was published in 1890, describing a woman with pneumonia who received about “200 gallons in twenty four hours” and improved.   However, Even the early pioneers of oxygen therapy strongly cautioned against large doses of the panacea “on account of the dangerous degree of stimulation to the system and the increased combustion of tissue” (1) In fact, almost every scientist and physician responsible for a significant advancement in the medical applications of supplemental oxygen added statements warning against overzealous and excessive oxygen usage. Yet somehow a “more is better” approach in acute care medicine and especially EMS has survived to the present day. Oxygen is often applied routinely as part of a protocol for conditions like chest pain, dyspnea and severe illness without an accompanying assessment to determine if it is actually indicated.  

So, why is supraatmospheric oxygen bad? It has been known for quite some time that newborns, especially those born prematurely, were are risk for damage to their eyes and other organs from increased oxygen exposure. Further research into children born with certain congenital heart defects (CHD) found that they were dependent on a patent ductus arteriosus (PDA) to circulate oxygenated blood to the rest of their body. Since increased oxygen levels in the blood (PO2) lead to closure of the PDA, these patients are often given limited oxygen at atmospheric or sometimes even subatmospheric concentrations to maintain PDA patency until they can get a surgical repair (2).

For adults, the dangers of supplemental oxygen are a little more nuanced with effects that are usually observed in the long term rather than acutely as noted in neonates. As oxygen surpasses adequate levels in the blood, arterial receptors send signals to reduce the vessel size, demonstrating oxygen as a powerful and fast vasoconstrictor(3). This mechanism is useful in the minutes after birth as a neonate converts from fetal to newborn circulation, but for adults this can cause problems that will be outlined in the Evidence section.

Incompletely metabolized or excess oxygen is also prone to increase production of oxygen free radicals, or reactive oxygen species (ROS). These molecules are necessary for certain function inside of cells, but an abundance of ROS can lead to cellular damage which is thought to exacerbate ischemia during heart attack and stroke.(4)

The Evidence: It is important to separate recent evidence supporting hyperoxygenation in preparation for rapid sequence induction and intubation (RSII) from research that addresses ongoing supplemental oxygen therapy. NO DESAT and other methods for oxygen administration prior to RSII are specifically designed for a patient with an imminent predicted period of extended apnea as a means to create a reservoir of oxygen in the lungs and in the plasma (5). Since active respiration will cease as a matter of course, it is imperative that we provide this extra inventory of oxygen in compensation for the patient’s failed ability to provide it for themselves. However, many patients who are candidates for RSII do not have respiratory pathology as the reason for their intubation and thus will likely require little or no supplemental oxygen after airway management is complete. Rather, they will only need positive pressure ventilation, and most can tolerate that at room air concentrations or slightly higher.

For patients who are not intubated and/or will not be intubated, using supplemental oxygen is very much like using any other drug. In fact, I’d say it’s exactly like using any other drug, and the evidence bears this out. The most recent development on this front is the AVOID trial, which studied the outcome of patients with myocardial infarction who received high flow oxygen versus patients who did not. An important feature of the trial was that they first separated the patients into groups that were hypoxic and those who were not, then randomized the latter group to either get oxygen at 8 lpm by mask or none at all. Long story short, the group that got indiscriminate oxygen had higher cardiac enzymes, bigger infarcts and more recurrent infarcts during their hospital stay (6). Similar studies in recent years have shown similar results, with one demonstrating a threefold increase in mortality in a group that received high flow oxygen versus compressed air(7). The main reason for this outcome is thought to be increased coronary microvascular constriction, and other studies have demonstrated this under observation in the cath lab.

The current version of ACLS makes reference to this in print an during the acute coronary syndromes video when it shows “Hugh” suffering his big, fat STEMI without receiving a single drop of oxygen.




Acute coronary syndrome and STEMI are not our only areas of concern when it comes to oxygen; however, though they seem to get the most attention. This is likely due to the anoxic nature of tissue death related to coronary artery occlusion during myocardial infarction. A greater population in transport for whom oxygen administration is a factor is the mechanically ventilated. People are intubated and put on a ventilator for many reasons that have nothing to do with their ability or inability to use and metabolize oxygen. As noted above, these patients would likely die without the mechanics of positive pressure ventilation but many do not need supplemental oxygen.


Ventilated patients with acute serious illness such as sepsis and ARDS are routinely hypoxic and as such often receive substantial amounts of supplemental oxygen prior to and after the initiation of mechanical ventilation. While this seems intuitive, mounting evidence suggests that this strategy may cause more harm than good in the long term. Conversely, these patients are much better served by increasing their mean airway pressure (MAP) with the application of PEEP to improve oxygenation.  It is not uncommon in the ICU and transport setting to see PEEP set as high as 15-20 cmH20 while trying to maintain as low a FiO2 as possible. Two studies found that increased FiO2 worsened oxygenation index over 48 hours and lead to increased days on ventilator and ICU days (8). There has been theoretical belief that oxygen induced vasoconstriction might be helpful to patients in either septic or hemorrhagic shock, but no study has found this to be true while other evidence suggest that deleterious lung effects would far outweigh any perceived vascular benefit. 

For other patients who are not intubated, specifically those with stroke or COPD, evidence is compelling that supranormal oxygen concentrations lead to poor outcomes. It has long been taught (this was pounded into my head during EMT school) that COPD patients would surely die if given anything more than two liters per minute of oxygen by nasal cannula thanks to the ominous “hypoxic drive” While this is indeed a thing, the number of people who actually live and die by hypoxic drive is very small. So, rest easy tonight knowing that you probably haven't killed anyone with a nasal cannula. However, multiple studies demonstrate poor outcomes for patients who receive indiscriminate high flow oxygen versus titrated oxygen based on clinical presentation. For patients with stroke, the microvascular constriction attributed to oxygen leads to decreased perfusion to the ischemic penumbra and thus has been blamed for worse outcomes for non-hypoxic patients who received high flow oxygen versus those who did not (3).

Discussion:


Oxygen. It’s easy, it’s intuitive, and it often makes people feel better, including the caregivers. The most likely reason it’s been left alone in most EMS, acute care and CCT protocols is the attitude that if it doesn’t do any good, at least it probably doesn’t do any harm. Now we know, with the available research, that this simply is not true. It can hurt, it probably does hurt and the frivolous application of oxygen “because the book says so” needs to stop.


Today.


Oxygen is a drug, and like any other drug it needs to be used judiciously. We wouldn’t dream of blindly starting a patient on a vasopressor like levophed because his blood pressure may fall without doing an assessment to first find out if he is actually hypotensive. Oxygen administration should be initiated the same way after the same assessment. Just as vasopressor therapy is for the hypotensive, oxygen therapy is for the hypoxic, not just the sick. 

We tend to take a “cover all bases” approach to caring and preparing a patient for transport to make sure we don’t miss anything. For example, patients who suffer traumatic injury, especially head injuries, are particularly sensitive to hypoxia and hypoperfusion. A single episode of either is associated with significantly increased mortality and morbidity. So, we often turn up the oxygen on the ventilator to unequivocally remove one of those hazards right from the beginning. However, both of these problems can be managed at the cellular level in the same way: ensure adequate mean arterial pressure to perfuse the injured brain with appropriately oxygenated blood. Theoretically, excessive oxygen will provide little benefit and may do harm by causing vasoconstriction upstream from the injury. And, if an attempt to hyperoxygenate a head injured patient is erroneously attempted with hyperventilation, the lack of CO2 will almost assuredly result in poor blood supply to the injured area.

It is also helpful, and important, to remember that there are four different types of hypoxia, only one of which has anything to do with a lack of available oxygen (aptly named hypoxic hypoxia"). Hypoxic hypoxia is usually suffered by someone in a place devoid of oxygen, like space. If your patient isn't in space, or in a room full of smoke or carbon monoxide, high flows of oxygen are temporizing at best. The other types of hypoxia: stagnant, hypemic and histotoxic are products of the body's inability to either transport, absorb or metabolize oxygen. To truly heal these conditions, you must isolate and eliminate the cause. Providing supplemental oxygen will only poorly manage one symptom without going any distance to fixing the problem. 

We should also think about how our care and reporting affects the initial care of those who take patients from us at the end of the transport. Reporting oxygen demand to receiving staff is as important as vasopressors and sedation; it lets them know where to begin. If you spent the entire transport at 100% FiO2 and the oxygen saturation was 100%, no one has any real idea what the oxygen demand is. And since we know that many of these patients do not and will not require that much oxygen, and that excessive oxygen can do harm, there is every reason to adopt a stepwise process for titrating oxygen to a goal of < 50% to keep SpO2 between 90%-94%, depending on the pathology(8). 

The bottom line is, no study shows the benefit of hyperoxia while plenty at least suggest that it causes harm. This should lead us to think of oxygen as a drug available to those who need it (blue people) rather than a shotgun blast of “appropriate care” or part of some silly mnemonic to help us remember the most basic tenets of medicine. In doing so, we tend to ignore the most important one. Do no harm.

Now, turn off the tap.

Thanks for reading. As always, feel free to comment here or on twitter, @Crit_Care_Excel.


References
1.       Grainge C, Breath of life: the evolution of oxygen therapy. J R Soc Med. 2004; 97: 489-493
2.       Reviews CT. Studyguide for Egan's Fundamentals of Respiratory Care by Robert M. Kacmarek, ISBN 9780323082037. Academic Internet Publishers; 2013.
3.       Cornet A, Kooter A, Peters M. The Potential harm of oxygen therapy in medical emergencies.  Critical Care 2013, 17:313. Available at http://ccforum.com/content/17/2/313
4.       Chabot F, Mitchell JA, Gutteridge JM, Evans TW. Reactive oxygen species in acute lung injury. Eur Respir J. 1998;11(3):745-57.
5.       Weingart S, Levitan R. Preoxygenation and prevention of desaturation during emergency airway management. Annals of Emergency Medicine. 2012; 59: 165-75
6.       Avoid the oxygen. Available at: http://www.scancrit.com/2014/11/26/avoid-oxygen/. Accessed November 27, 2014.
7.       Wijesinghe M, Perrin K, Ranchord A, Simmonds M, Weatherall M, Beasley R. Routine use of oxygen in the treatment of myocardial infarction: systematic review. Heart. 2009;95(3):198-202.
8.       Rachmale S, Li G, Wilson G, Malinchoc M, Gajic O. Practice of excessive F(IO(2)) and effect on pulmonary outcomes in mechanically ventilated patients with acute lung injury. Respir Care. 2012;57(11):1887-93.


Friday, November 14, 2014

Crew Configuration: Feet, Urine and the Value of "Been There"

A staple in all of my airway lectures is "every game in critical care transport (CCT) is an Away game", simply meaning that people seldom bring patients to you at your base. No, you have to go get them in your vehicle of choice, do things to them and then do the job they called you for in the first place, which is to cart them off to somewhere else so other folks can do things to them. Doing this in either in someone else's place (hospital or ambulance) or a small, mobile environment brings with it a constantly elevated level of stress that comes from the fact that you can only control that environment so much. Sure, once you're in the ambulance or aircraft, that place is yours, but even that place is small and cramped and  in motion and only contains the supplies you brought with you. A hospital, by contrast, practically has oxygen and IV fluid flowing from the walls; making even someone else's hospital room a tiny bit better than your own magic flying chair. 

Stress.

Three things are crucial for mitigating this kind of inherent stress that cannot be eliminated: Good training, good experience, and most of all, a good team. 




Although the original air medical service was strictly a mode of transport, using a pilot to carry unattended patient in the back or even outside the aircraft,  the use of highly skilled teams evolved rather quickly in 1960’s and 70’s. Like the early EMS ambulances, these teams often included physicians and, in many parts of the world still do.  As time passed and the services grew, physicians in the US were largely replaced by specially trained transport clinicians, mostly nurses. Later still, these teams evolved into more diverse teams comprising paramedics, respiratory therapists and other clinical specialists on an ad hoc basis. The subject of just who is a part of this team is addressed in most CCT textbooks and courses as a matter of information about the prevalence of particular team compositions, but most of these do not include a discussion about which team is best for patient outcomes.  The Commission on Accreditation of Medical Transport System includes a requirement that a critical care transport team must “consist of a specially trained physician or a registered nurse as the primary care provider”(1), but says that team may be completed by any of a list of credentialed medical providers as long as there are two people on each transport.  

A team.

So, that leaves the question: Which crew configuration is best for air medical transport? Spoiler alert: I’m not going to answer that. As a matter of fact, I’m not even going to ask it. The honest truth is that there is very little evidence to suggest one blend of credentials is better than another for patient outcomes, leaving it largely to opinion, hearsay and conjecture. But, as far as facts go, the 2000 Medical Crew Survey by William Rau (2) finds that 71% of air medical crews that use at least a two person team consist of an RN and a paramedic. The findings of my own survey are very close to that (68%) and this number has hovered around 70% for the past 20 years. The stated purpose of this blended crew configuration is summed up well in this passage from a critical care transport textbook:


                “…the most common configuration is flight nurse/paramedic, a synergistic combination that provides a great amount of experience and diversified training in the medical crew. The flight nurse is well experienced in the critical care environment, whereas the flight paramedic is well adapted to airway management and emergency scene management. Both providers are proficient in dealing with the comorbid or multitrauma patient.”(3)

On the surface, this makes perfect sense. Find people who are experienced with critical care and people who are experienced with technical skills and transport and put them together transporting critical care patients who often need the benefit of technical skills. And, in case you missed it, make sure they are well trained and experienced. I used to work with a very experienced ICU nurse who could usually divine the patient’s problem by examining their feet and their urine. It’s pretty hard to teach that sort of thing in school. Rather, you have to see lots of feet and lots of pee before you start putting that together on your own.

So, what is borne out, at least anecdotally, is that training and experience matter the most. I’ve always thought one of the greatest things about transport is that we don’t hire new grads, no matter what the license. We appreciate that the autonomy of our position requires critical thinking and exposure that is not available in the classroom. A joint position paper by the Emergency Nurse’s Association (ENA) and Air and Surface Transport Nurse’s Association (ASTNA), as well as a position paper from the International Association of Flight and Critical Care Paramedics (IAFCCP, formerly IAFP), both state the importance of specialized training and copious experience in the respective areas of expertise of nurses and paramedics prior to entering transport (4,5). A cursory examination of CCT job posting on flightweb.com (6) reveals that most employers seek a minimum of 3-5 years of experience working under their credential to qualify for an interview, regardless of what that credential is. What is more prevalent, and interesting to me, is this line right here:

Almost every employer in the market for a new flight nurse or paramedic doesn’t want a new one at all. Rather, they want someone who has done the job before, and there is no question why. Of course, to be experienced flight nurses and paramedics, those same people had to be new at one time, but given the choice, employers usually prefer seasoned transport vets over rookies. So, it is implied that the job of a flight nurse or paramedic is a different job than either of those things in their native environment (a hospital or 911 EMS) and as such, an experienced flight nurse (or paramedic or RCP, etc) will know how to do the job of transport, not just the original job for which they were educated. As the book states, paramedics may be hired for their expertise with airway skills, but speaking for my program, the transport nurses intubate also and have to maintain the same competency. The same can be said for blood administration, vasopressors and central line monitoring. These things are part of almost no job description for a 911 EMS paramedic that we hire, yet they are things our paramedics are expected to learn and become proficient. All of these skills are covered on both the Flight/Transport Nursing and Flight/Transport Paramedic exams (7,8), lending more credence to the notion that transport is its own brand of healthcare and requires its own brand of healthcare provider.

This brings me to the question I am going to ask: Is there a magic number of years or transports that bestows upon a nurse the technical skills or a paramedic the theory that they move forward from his own license to something more inclusive, like “Transport Practitioner”? In other words, how much experience does a Flight __________ need before s/he knows the job so well that it doesn’t matter who their partner is? 


I have no idea, so I asked you, my readers, a few questions about the crew configurations where you work, how you feel about them, and how comfortable you feel about your teammates.


The Survey


The survey contained 18 questions that required answers as well as on optional comment box at the end. The questions and available answers were:
CLICK TO ENLARGE


The purpose of the questions was to make people think, maybe for the first time, about how their team dynamic really functions. I purposely avoided questions about equal pay or equal scopes of practice because I didn’t want it to seem adversarial. A few respondents found ways to be adversarial anyway, and I think that’s to be expected. Mostly though, the results were civil and positive and went a short distance to restoring faith in humanity.

The Results: I’m not going to list results for every question because, quite frankly, the overall results weren’t that surprising. Here are the highlights:

351 people responded in total, broken down below by credential, transport experience and total medical experience
















The most promising thing I took from the demographics was that no one reported less than three years of total medical experience, and 98% reported at least five years.  This says to me that we’re doing a passable job of keeping really new people out of transport. However, I’d wager that this same survey taken ten years ago would have had very few respondents with less than ten years of medical experience, if any at all. As flight and CCT services grow to add more resources, some employers have gotten a little less selective about the background and experience they demand of their applicants. 

Mission profiles, service types and crew configurations:
 


Again, no real surprises here, at least not to me. Most respondents do more interfacility transports than scenes, they do most of them by helicopter, and they do them as part of an RN/paramedic team.  Under services, only 12 people answered that their service provides all four modes of transport, while the most common combination was ground + rotor + 911 (81). Even so, there were more people who answered they did rotor only (95) than any of those combinations. This could reflect growth in corporate air medicine which is typically single mode.

The crew configuration data followed the reported averages for the past 20+ years when it comes to the RN/Paramedic team reported at about 69%. No other team makeup even came close. There were a fair number of “Other” responses to this question which included assorted military configurations and civilian variations that involved more than two crew members or a pool system that included multiple disciplines that were assigned per flight based on need.


Most survey respondents were involved in direct patient care and did transport as their full time job.  

The rest of the survey dealt with the opinions that transport professionals have of themselves and their teammates regarding clinical competency. One of the first things I found when sifting this data, and honestly when writing the questions in the first place, was how difficult it is to ask these questions at all. The idea is simple; find out if CCT providers believe in the value of blended crews, and to find out if they personally benefit from the expertise of a differently licensed teammate. However, finding a way to ask those questions without sounding like any team member was any less valuable than any other proved to be a little more difficult. So I asked them through a series of smaller questions. 

“Do you believe that the team members at your current/most recent transport program with similar experience are similarly capable, regardless of credential?”

The overall answer to this was yes, to the tune of 83% of all respondents. Most of us believe that our peers are just as good as we are. If we limit the responses to those who actually work in RN/Paramedic, that figure goes up to 88%. Nurses, paramedics and nurse/paramedic professionals all agree with this statement by at least 85%. The majority of people in non-blended crews believe their teammates are as good as they are, which is not surprising at all since they all have the same license. 

“Do you believe that you are similarly capable to the team members at your current/most recent transport program, regardless of credential?”

This answer, too, was yes at 93%. When controlled for people who work in blended crews, 95% believe they are as smart as their teammates. The individual credentials (RN, Medic and RN/Medic) also believe this to be true in very high numbers, over 94%. In CCT this is perfectly understandable; a bunch of Type A personalities who absolutely believe they are at least as smart as the people they work with, and maybe a little smarter.

 “Do you believe that the members of your team with the same credential could safely and effectively complete any transport (excluding specialty care)? (Example: Two paramedics could complete a transport without a nurse, and vice versa)

What is interesting about this is, in spite of the overwhelming belief in the first two questions that everyone is as smart as everyone else, only 68% of the total respondents agree with the above question. This gives much weight to the idea that blended teams really do matter to the team members themselves. If we control for only people working on blended crews, the number remains static at 68%. Broken down by the credential of the respondent in a blended crew, 87% of paramedics believe that either they or their nurse partner could complete transports with another provider with the same license, while 57% of nurse/medics think that. Only 48% of the nurses who report working in a blended crew agreed with the idea of their paramedic partners transporting a patient with another paramedic instead of a nurse, or two nurses transporting together. Since the majority of people reported that interfacility transports were the bulk of their mission profile, then it is reasonable to think that nurses believe that a nurse should be on that type of transport, regardless of how experienced a paramedic or other team member may be. When compared to the next question, this result makes even more sense.

“The stated purpose for a blended crew configuration for non-physician transport teams (RN/Paramedic, RN/Resp, etc) is to bring different skill sets and knowledge bases to the transport team. How strongly do you agree with that statement?”

Nearly everyone who responded agrees with the statement above, with the greatest number (94%) among those who work on a blended team. Even ten out of the 12 nurses who reported working in a homogeneous (RN/RN) configuration agree that a blended team is a good idea. I can surmise from this that we as an industry truly believe in the value of bringing different skill sets to the business of transport.

“Do you believe that experienced team members benefit from the blended crew configuration? Do you believe that new team members benefit from the blended crew configuration?”

Clearly, those who believe in blended teams believe in them for everyone on every trip. A few more people thought that new people would benefit than thought experienced do, but not by much. Some of the comments recommend that nurses new to transport might benefit from orienting with a paramedic, and vice versa. Mostly, the comments were nearly direct quotes and paraphrases of the book passage cited earlier about nursing bringing critical care hospital skills to the team and paramedics being experts in scenes and airways.

 “How many years of transport experience should a team member have before they can effectively transport any kind of patient with any other team member, regardless of credential? (Excluding specialty care)”

This question was meant to determine when people thought you might go from being a “Flight_______ (nurse, paramedic, etc)” to being a “Transport Practitioner”, and the most common answer was 3-5 years. However, this question is better summed up in the comments, and these two said it best to me: 

“After 5 years, you can either do the job or you can't. It's different from ICU or EMS; it's transport medicine.” And,

“This shouldn't happen.”

“As as a transport clinician, how much responsibility do you take/should your employer take for acquiring the knowledge and skills usually attributed to your teammates with other credentials? (Example: As a paramedic, how much responsibility do you take for learning things typically perceived to be part of nursing expertise such as blood administration, advanced medication infusions, intra aortic balloon pumps, etc?)( Example: As a nurse who has never intubated before, how much responsibility should your employer assume to teach you that skill?)”

These questions are combined for simplicity since they have peripheral bearing on the subject at hand. Basically, I’m asking who should drive cross training of skills in a blended crew environment. Not surprisingly, most CCT providers take ownership and most of the responsibility for their own education and training (81%). Only two people felt they had no responsibility and I openly found myself hoping to never be paired up with either of them. 67% of people believe their employer has most of that responsibility. Many people answered both they and their employer had full responsibility, making me believe those people either do or wish to work in vigorously collaborative work environments. 

“Do you believe your leadership encourages and empowers the team at your current/most recent transport program to learn beyond their scope of practice?”

This question gets to the heart of cross training and learning beyond the reason and license for which you were hired. 84.1% of respondents believe their employers stand behind, encourage and provide the tools to learn at their job. A few comments revealed disappointment that this isn’t so, but most were positive.

Open Comments: (I offer a few with no comments of my own, and these in no way reflect my opinion)

“I'm not a proponent of our RN/Medic model. While we have good medics, the overwhelming majority take no time or responsibility to learn outside their so-called "street medicine". I'd rather have RN/RN crews with a strong background in ICU and a bit of ER. In my opinion, this is much more useful in our program, where interfacility ICU patients are far more challenging to manage than a typical scene, STEMI or trauma. Medics were brought in to appease the state board of EMS and provide a less-expensive option.”

“Flight medicine is neither nursing, nor paramedicine. We all learn from each other, and learn skills/techniques/knowledge beyond our traditional nursing or paramedicine roles.”

“I like how our team is configured. Paramedic/RN, but I don't care for the insinuation that paramedics could not do this job without and RN....frankly, I feel that paramedics bring the most relevant experience to the job. If you can't take care of the airway, none of the other "stuff" matters. Most "nursing" skills can be taught to paramedics in a week, the same is not true for teaching RN's paramedic skills. As a woman in this industry (HEMS) I hate the stereotype that I am the nurse and my male partner is the paramedic. My employer is good at providing education, I just think we should get more, and be at the leading edge of the HEMS industry.”

“Physicians should form part of the operational crew. Their depth of medical knowledge and leadership is grossly under-valued and denying them operational opportunities is NOT in the patient’s best interest. Learn from London HEMS in UK - world leaders in this field.”

“Any 24 year old with 6 months experience who's successfully challenged the FP-C can work here”

“Teamwork is encouraged, but not always practiced.”

“I believe it is harder for the medic to obtain CC nurse skills than it is for the nurse to obtain the medic skills. Nurses live in the CC world in ER and ICU 40+ hours a week with constant patient loads whereas there is alot of down time in EMS and usually not much critical care (CC)”

Discussion
I begin the discussion with these two comments from the survey:

“When a Paramedic or RN has done the job 5-10 years. There is no reason why the crew can't be RN/RN or Paramedic/Paramedic. You should know the job by this time.”

“Question 15 is a poorly written question - it assumes that I can take on the role of my colleague through experience only gained in the transport environment - a nurse will not gain expert proficiency at managing ground scene calls as a first responder if they only do a few such calls a year - similarly a medic will not gain proficient 'independent' ICU level care when they only care for a small number of complex cases every year - you become an expert at what you so every day - and it is a unique service that provides the call volume, acuity, and oversight to provide a foundation to ones partners specialty – thx”

The first comment gets to the heart of what I wanted to say, and what I wanted to know from others. Does someone who does transport for a length of time move away from their exclusive license and move toward being a transport clinician, just like the folks around them? And if that’s true, how long does that take? One year? Five years? Ten? I just don’t know. This commenter put that into better words and even gave a time line, though I’m not sure I agree with that.

The second comment pretty well opposes the first, holding that paramedics are scene experts and RN’s are ICU experts and that’s how it’s always going to be. I don’t think I believe that either. I work with quite a few 20+ year nurses who have been doing transport for at least 15 years, and I have never once looked at any of them and thought “Man, I’m sure glad she worked in an ICU in 1991”. Rather, I've thought many, many times “Wow, I’m really glad she’s done 5000 transports and she’s with me today” 

By assuming that my transport competence comes from my scene management experience, you’re giving me credit for something I haven’t done in almost 14 years instead of recognizing that I am a transport practitioner, who knows flight medicine and does it really well, regardless of the card in my pocket. Medicine is constantly changing regardless of where you practice it, but we learn to manage those changes where you are, not where you were. True, I know how to work on a scene, but the most important lessons about scenes are the lessons I learned in elementary school: Don’t play in traffic, don’t put your fingers where they don’t belong, and don’t pick a fight with someone bigger than you. The pearls of an ICU are a lot more complex and come later in life, but they are just as teachable to someone willing to learn.

Willing to learn…that’s the other side of this. A big majority of those people surveyed said they take full responsibility for their education, and almost as many said their employer shares the responsibility and empowers them to get the education. That’s huge, because transport medicine is hard. In short, take all those skills you were hired for, double them, then apply them while wearing a blanket and sitting in a metal shoe box. And oh yeah, be quick about it. So, if you want to do it, it’s work. And a lot of that work has nothing to do with the license and skills for which you were originally educated and hired. It takes drive and passion to learn the rest, and people without those two things will most likely fail.

However, if you do the work and put in your time, you get to part of a brotherhood and sisterhood of exceptional professionals, and I believe that with that membership comes the identification of something greater than and beyond your license. You might have been hired because you were a nurse, but you continue and succeed because you became a transport nurse, and there is every reason to believe that you are capable to do any (non-specialty) transport with any partner, because transport is what you do. The same goes for paramedics, or RCP’s, or physicians, or whomever I missed.

What’s the best crew configuration for patients? An experienced one.

Thanks again for reading. Feel free to comment here or on Twitter @Crit_Care_Excel, and visit the website, www.critical-care-excellence.pro.

References
1. Commission on Accreditation of Medical Transport System. Accreditation Standards. 9th Edition. October 2012. Available at: http://www.camts.org/Approved_Stds_9th_Edition_for_website_2-13. Accessed November 13, 2014.
2. Rau W. 2000 Medical Crew Survey. Air Medical Journal. 2000; 6: 11-13
3. American Academy of Orthopaedic Surgeons, American College of Emergency Physicians; lead editors, Michael Murphy. [et al.]. Critical Care Transport. Jones & Bartlett Learning; 2009.
4. Air and Surface Transport Nurses Association. Staffing of critical care transport services. 2010. Available at: http://www.astna.org/PDF/ASTNA-Staffing-PositionPaper-7-9-8. Accessed November 13, 2014.
5. International Association of Flight and Critical Care Paramedics. Critical Care Paramedic Position Statement. July 2009. Available at: http://c.ymcdn.com/sites/www.iafccp.org/resource/resmgr/docs/critical_care_paramedic_posi. Accessed November 13, 2014.
6. FlightWeb Jobs Center. Available at: http://www.flightweb.com/jobs/. Accessed November 13, 2014.
7. Board for Critical Care Transport Paramedic Certification. Candidate Handbook. August 2013. Available at: http://www.bcctpc.org/FPC/documents/BCCTPChandbook. Accessed November 13, 2014
8. Board of Certification for Emergency Nursing. CFRN Content Outline. Available at: http://www.bcencertifications.org/Get-Certified/CFRN/Study/CFRN-Content-Outline.aspx. Accessed November 13, 2014.

Thursday, November 6, 2014

Out with the Bad Air, in with the Good Air

Oxygen. It’s a little funny to me that we’re still talking about this, even a little. Story after story of poor airway management that leads to death permeate medical publications and professional journals, so much so that they routinely spill over into social media and mainstream news. How is it possible that something so simple that we as a medical community understand so clearly still results in even one death in 2014? Yet it does, and here we are.

I would argue that deaths from hypoxia related to airway management are less about ignorance than they are about arrogance. Any 4 year old knows if you hold your breath, you’ll turn blue and pass out. Where the toddler has the advantage in this situation is they are smart enough not to forcibly do that to another person. Those of us tasked with airway management often suspend that particle of wisdom and inflict such serious harm that I heard it recently described by a medical director as “one or two clean kills a month”. That is crazy and, more importantly, totally preventable.

The key to preventing a hypoxic death during rapid sequence induction and intubation (RSII) is to prevent hypoxia. The easiest way to do that to avoid RSII altogether. However, clinical conditions often preclude that choice. So, if we can’t not RSII, then we must do something that comes as close to guaranteeing adequate oxygenation as is humanly possible.

Many RSII protocols simply include a step that includes some variation of the language “Preoxygeanate”. While this is technically accurate, it is miserably vague without proper direction on tools, techniques or timeframes for getting this done. This is especially sad since there is a plethora of evidence to explain exactly how best to do this for the majority of patients.

The history: The concept of RSII is not new to medicine or even to prehospital and transport medicine. Anesthesiologists developed the procedure to safely induce anesthesia and secure the airway of surgical obstetrical patients who were not ideal candidates for general anesthesia induction due to hemodynamic instability or an undocumented fast prior to surgery (1). The process involves the injection of a fast acting sedative and neuromuscular blocker in rapid succession to induce unconsciousness and gross muscle relaxation, thus creating the most hospitable intubating conditions. In transport, we electively perform RSII for patients who meet criteria based on mental status, unstable airways, worsening respiratory status or anticipated clinical course. RSII is not without risks of course, some those being medication allergy, hypotension and failure to achieve the stated goal which is a secured airway. The most common risk, and one of the most dangerous, is hypoxia associated with the requisite apnea that comes with global neuromuscular blockade, and this was one of the first problems that anesthesiologists had to solve.

Science and evidence: Once the paralytic is administered and takes effect, the patient can no longer spontaneously breathe, guaranteeing rapid desaturation and tissue hypoxia unless purposeful steps are taken to actively provide oxygen. This can be done with a BVM and attached reservoir during the apneic period, which will provide up to 97% FiO2. However, positive pressure ventilation increases the risk of gastric insufflation and subsequent vomiting which is particularly dangerous for the patient now unable to swallow or cough. The best prevention for all of these unwanted effects is to proactively build adequate alveolar and plasma oxygen reserves to last through the apneic period during which laryngoscopy and intubation will take place; and do so prior to the induction. This step, simply referred to as preoxygenation, is taught in many airway courses, RSII programs and difficult airway management classes as part of the “P’s of RSII”(2). The idea is simple: displace the carbon dioxide and nitrogen in the patient’s lungs by instilling high flow, high concentration oxygen for a minimum period of time prior to the induction. As part of the process, blood PO2 and oxygen saturation will rise, though these effects will be lesser over the short term. Then, as apnea ensues post induction, the patient will have significant stores available to maintain blood oxygen levels without breathing or, in most cases, any active ventilation at all. Early pioneers of RSI found that safe apnea times could be significantly extended by providing patients with oxygen concentrations greater than room air prior to intubation. Later studies found that a properly preoxygenated healthy patient can maintain oxygen saturations of greater than 90% for up to eight minutes, affording the intubator ample time to perform laryngoscopy and secure the airway before reoxygenation becomes necessary. The problem with reliance on this method is twofold. First, while desaturation occurs relatively slowly in the beginning, once SpO2 falls below 90% the decline towards zero oxygen saturation occurs very rapidly as the patients enters the “steep side” of the oxyhemoglobin disassociation curve. Without the provision of additional oxygen, the risk of secondary brain injury, cardiac dysfunction and death increase greatly. Secondly, the original studies about safe apnea time used healthy volunteers, while the patients who require emergent RSII are usually by definition not healthy at all. For example, morbidly obese patients can lose up to 25% of their functional residual capacity when they are lain supine. When they undergo anesthesia, they can lose an additional 25% (3) Therefore, the steps we take to preoxygenate these patients that would provide safe apnea times of up to eight minutes in “healthy” adults would allow for less than half of that time in this population.

To protect against this desaturation and the negative effects that result, Drs. Weingart and Levitan make several recommendations for RSII preoxygenation in the emergency department that are equally applicable to the transport environment.


1.       NO DESAT (Nasal Oxygen During Efforts to Secure A Tube) In a 2010 article (4) ,Dr. Levitan summarized the old notion of providing oxygen via nasal cannula before and after induction to prolong the safe apnea period. This is not unlike methods used to oxygenate patients passively during brain death testing. In these studies, patients are disconnected from the ventilator to allow their PCO2 to rise while oxygen is instilled without positive pressure via a catheter in the ET tube. While the carbon dioxide levels in the blood continue to climb, oxygen saturations remain at or near 100% and allow for a safe assessment of respiratory drive (5). This works based on two principles. First, oxygen instilled into the nasopharynx at high flow rates (> 15 lpm) flushes the upper airways with oxygen (1) concentrations much higher than we normally think possible with a nasal cannula at lower flow rates. This greatly increases the FiO2 of each inspired breath that the patient takes on their own or that is delivered via PPV. Secondly, because of the solubility of the oxygen and relative negative pressure of oxygen in the alveoli during the apneic period, nasally delivered oxygen will be drawn downward through the trachea and into alveoli where it can diffuse into the capillaries at up to 250 ml/min (1). Studies with apneic oxygenation have shown a near doubling of safe apnea time (SpO2 >92%) vs room air. The nasal cannula can be applied as soon as the decision is made to intubate as part of the preoxygenation regimen; and it can be left in place and flowing regardless of the other devices used to oxygenate (BVM, NiPPV, NRB, etc). Also, it can and should be left in place for the duration of the RSII until the ETT is placed, confirmed and secured.

2.       Two oxygen sources for every intubation attempt. This is not expressly mentioned in the article, but it is implied by the mention of NO DESAT and other oxygenation adjuncts used simultaneously. At a minimum, you should be able to generate enough flow to run two of these devices at 15 lpm. A two port adapter on a high flow source may be adequate, but the best practice would be to have two separate oxygen sources to maximize flow and available oxygen resources. This doesn't differ much from the proper RSII preparation already in place.

3.       Avoid BVM if at all possible.  Before the induction, and especially after, it is best to allow the patient to oxygenate themselves if their respiratory effort is adequate enough to do so. Pressures of as little as 25 cm/H20 can open the esophageal sphincter and allow air to enter the stomach and pressurize the gastric contents, increasing the risk of vomiting and aspiration during the RSII (1). Therefore, if the patient is breathing at all, a standard partial rebreather mask with reservoir (commonly called a non-rebreather mask by EMS and ED personnel) delivering oxygen at >30 lpm is preferable. This, combined with NO DESAT at >15 lpm will provide nearly 100% FiO2 without generating any PPV at all. It is understood; however, that some patients simply cannot breath adequately enough to achieve the necessary level of oxygenation. For these people, see #4.

4.       If you have to BVM; do it slowly, at low volume and use a PEEP valve.  As stated above, it doesn’t take much pressure from a BVM to push air into the stomach, especially for excited or inexperienced providers and in the absence of optimal airway positioning. So it is preferable to wait to start bagging until after the ET tube is in place. But if your patient is so acutely ill that independent oxygenation with a mask and NO DESAT is not possible, you will likely have to use positive pressure to achieve acceptable pre induction saturations. If bagging is your only option, remember these things:

·         Ensure a good, tight mask seal: This is probably the most important step to ensure adequate oxygenation with a BVM. Ideally this is a two person job: one to hold the mask seal and open the airway; the other to squeeze the bag. It is preferable to use nasal and oral airways if possible to maximize BVM effectiveness.
·         Go Slow: Delivering BVM ventilation at a rate of 6-8 bpm with each breath over 1-2 seconds will help to keep the inspiratory pressure below the threshold that would open the esophageal sphincter. The long inspiratory time will also increase mean airway pressure (MAP), a vital component in maintaining oxygenation.

·         Low Volume: Aim for a tidal volume (Vt) of 6-7 ml/kg of ideal body weight (IBW). The lower volume coupled with long inspiratory time should help keep the pressure right about where it should be to avoid aspiration dangers. So how do you set a desired Vt on a BVM? Unless you can measure exhaled Vt through an anesthesia machine, it’s difficult. But, you can know how much Vt your BVM is capable of delivering and work from there. Here is the package insert from a typical BVM:





The most air you can squeeze out of this bag is 850 ml (Maximum Stroke Volume). This is much more than any patient would need based on IBW.  And, by the “Delivered Oxygen Concentration” table at the bottom, you can also see that a volume that large is pretty inefficient for the purposes of oxygenation.  Even volumes of 600 ml as noted in the table would be pretty large related to the IBW of most patients we transport. With that in mind, remember long, slow squeezes of the bag that are enough to make the chest rise.
·         Use a PEEP valve: The purpose of PEEP is to increase MAP, a fundamental component of oxygenation. By applying pressure to the end of expiration, the alveoli are never allowed to fully empty and collapse, leaving oxygen rich air in contact with the alveolar capillary membrane longer and allowing it to diffuse under this pressure. When coupled with NO DESAT, the extra oxygen + pressure will provide a CPAP effect and ultimately extend safe apnea times. 

5.       Stop the intubation attempt when SpO2 reaches 93%, not 90%.  Peripheral pulse ox sensors tell you less about the patient’s hemoglobin saturation now than it tells you about what the saturation was 30-45 seconds ago thanks a concept known as pulse ox lag or latency. And, if your patient is poorly perfused, hypothermic, or in a cold environment, that lag time could be up to two minutes (6). Therefore, when the SpO2 from the right index finger probe reads 90%, the actual percentage of bound hemoglobin is probably closer to 85% and dropping fast. And, from what we know about the oxyhemoglobin disassociation curve, we know that that oxygen saturation will fall precipitously after it drops below 90%, making it difficult to recover before severe hypoxic injury becomes likely. With these two ideas in mind, it is much safer to think of a peripheral SpO2 of 93% as the lowest acceptable before ceasing an intubation attempt and resuming oxygenation. In the literature and in practice this has led to fewer critical desaturations and better outcomes. 

Clinical considerations:  Good RSII training and drills already involve much discussion of preparation and preoxygenation, so adding these steps should be pretty easy. Logistically, we can add a nasal cannula to the intubation kit inventory and PEEP valve either to the same inventory or to every BVM. The protocols can also be updated to reflect specific methods, devices and times for proper preoxygenation.

Discussion: It is often presumed and expected within our industry that critical care transport clinicians are experts in RSII and general airway management. That is something that we can be truly proud of, but something that we also must earn every time we are called upon to transport a patient in need of this important, time critical skillset. In order to maintain the confidence placed onto us by our peers, we must continually train, drill and educate ourselves to make sure we’re taking the best care of our patients. The methods detailed above represent the most current, evidence based techniques for improving oxygenation during the requisite apneic period following neuromuscular blockade and should be employed with every RSII. The techniques cited in these studies differ somewhat from our current practice, suggesting by the research and results that our standards need to be reviewed and updated to reflect industry best practices. Whatever your feelings about the bougie or video laryngoscopy or any other tool, it’s pretty hard to argue with the value of oxygen, or more importantly the negative value of its absence. There has been much in the news lately of patients suffering anoxic brain injury that can be directly linked to poor airway management by EMS and transport crews. This possibility is real each time we care for a patient with an advanced airway in place, but it is especially applicable to those patients in whom we perform the induction and place the airway ourselves. By employing our sound clinical judgment, following our protocols and providing oxygenation in the manner described above, we should be able to avoid oxygen desaturation in nearly all of our patients. 

References
1.       Weingart S, Levitan R. Preoxygenation and prevention of desaturation during emergency airway management. Annals of Emergency Medicine. 2012; 59: 165-75
2.       Walls R, Murphy M. Manual of Difficult Airway Management, Fourth Edition. Philadelphia, PA: Lippincott. 2012
3.       Damia G, Mascheroni D, Croci M. Perioperative changes in functional residual capacity in morbidly obese patients. Br J Anesth. 1988; 5: 574-78
4.       Levitan R. NO DESAT!. Emergency Physicians Monthly. http://www.epmonthly.com/archives/features/no-desat-/ Published December 9 2010. Accessed October 2, 2014
5.       Wijdicks E, Varelas P, Gronseth G. Evidence-based guideline update: determining brain death in adults. American Academy of Neurology. 2010; 74: 1911-18
6.       David D, Aguilar S, Sonnleitner C. Latency and loss of pulse oximetry signal with the use of digital probes during prehospital rapid-sequence intubation. Prehospital emergency care. 2011; 15: 18-22