 Welcome everyone, we are going to be talking today about the Transesophageal Echo Equipment Infection, Control and Safety. This is part of the lectures for the Toronto General Hospital Fellows, the Cardiac and Stasis Fellowship as part of the preparation for the National Board of Echo from June the 19th, 2019. So, you know, I don't have any disclosure to discuss with you guys, so we are going to go direct to the index. We are going to talk a little bit about the equipment, indications, contraindications, how to manipulate the probe, how to maintain the probe. We are going to talk about infection control, we are going to talk about safety, probe insertion, complications, biological effects and the safety of ultrasound. Ok, so equipment. So, Transesophageal Echo has several indications. The last review from the American Heart Association guideline updated for the clinical applications of echocardiography was published in circulation in 2003. And they state that as a class 1 indication for TE is the repair of a complex, repair or complex valve replacement, history of hypertrophic obstructive cardiomyopathy, dissection with thyroid valve involvement. As a class 2A, which means weight of evidence and opinion is in favour of the use and effectiveness, is any surgical procedure which has like risk of myocardial ischemia, MI or hemodynamic disturbances. And the big debate came up with the class 2B indication, which means usefulness and efficacy is less well established. So, this is the situation that we are going to find in an off-pump, or the coronary bypass for evaluation of regional myocardial function, something is going to happen with evaluation of coronary anatomy or graft patency. So, those two indications are related to standard on-pump ACVs or even like long transplantation is a class 2B for checking of the graft patency or the anastomosis on the pulmonary veins. And then it's when the risk and benefits needs to actually be pondered and make a formal decision if you can or can't do TE. So, in 2013, from the American Society of Echo, there was an update and basically what they described is that interoperative TE is required always when it's an all open heart for valvular replacement, as we were mentioning, or valvular repair, or if you have a thoracic-artic surgical procedures, anything involving the ascending aorta, thoracoatominal repairs, and then they recommend in some coronary artery bypass graft surgeries, what we normally do at our center is whenever there is an impairment in the systolic function, which is more than mild, then we suggest and we recommend to actually go ahead and do it. And then you can actually, the third statement is non-cardiac surgery, but patients that have known or suspected cardiovascular pathology which may impact outcomes. It's important to, like in critical ill patients, is any patients where the trans thoracic images are not able to be obtained. So, contraindications. So, the first report that we got is from 1999, from the American Society of the Efeco and the SEA guidelines, which states that the absolute contraindications is known as esophagus, a previous esophagectomy or esophageal gastrectomy, an esophageal structure, an esophageal tumor or diverticulum, or an esophageal trauma whenever you have a perforation or a laceration, otherwise it's a relative contraindication. So, the fact of having a recent esophageal gastric surgery is again a relative contraindication, the same thing that an atrial tracheoesophageal phase 2. So, that's from 1999. So, in May 2010, there was like a practice guidelines from the SEA, the Board Update, in conjunction with the American Society of Anesthesia, which states that the T might be used for patients with oral esophageal or gastric disease if the spectra benefit avoids the potential risk, provided appropriate precautions are applied. So, at the end it's a balance and you guys need to decide. The last update from the American Society of Efeco from 2013, it keeps saying exactly the same statement. Absolute is going to be a perforated viscose, an esophageal structure, tumor diverticulum, or an esophageal perforation or laceration, but they include a new thing, which is the, as you can see here, the active upper GI bleed. So, before it wasn't included, and then since 2013, an active upper GI bleed is an absolute contraindication. And then on the right-hand side, you can actually see the relative contraindications and one of the things that we were always discussing when we are actually doing TE is if the patients with Yata learning are an absolute contraindication for transesophageal echo and they only mention it here as a relative contraindication. So, now we have talked about the contraindications and indications of TE. We are going to follow up with instrument controls. So, basically what we want with those controls is to adjust the image based on the anatomical structures that are displayed. So, you need to optimize your image for the structures that you are assessing. So, each structure is examined in multiple imaging planes, and from there we have more than one transducer position. So, basically the possibilities that we have in transesophageal echo and that's what we'll describe in the comprehensive TE examination from the American Society of Echo Guidelines in 2013, you can advance, withdraw your probe, turn left, turn right, and the flex, retoflex, flex to the right and flex to the left. And on top of that, you can rotate your omniplane from 0 degrees to 180 degrees. Okay? So, the way of actually mentioning all that is we call superior when you go towards the head, inferior when you go towards the feet. So, superior and inferior, and then you advance and you withdraw. Anterior and posterior, you can actually achieve it with antiflexion and retoflexion, which is anterior towards the sternum, posterior retoflexion towards the spine. You have the advanced drawing that we previously mentioned and then you can rotate towards the right clockwise, towards the left, counterclockwise, and you can rotate the omniplane from 0 to 180 degrees. Okay? So, when we rotate our angle, so when we start at 0 degrees, you basically are cutting the heart in half, showing the four chamber view where you have on the right side of the screen your left ventricle and on the left side of the screen your right ventricle. Okay? So, when you go to 90 degrees, if you are focusing on the LV, what you're going to have on the right side of the screen is going to be your anterior part and on the left side your inferior. And again, if you incremented it to 180, what you are actually obtaining is a flip image from your fourth chamber. Okay? You are very familiar with the angle manipulation. We are not going to comment anything else on that. Okay? So, instrument manipulation. So, those are the classical probes. This specifically is an X7 Phillips probe. Same thing for the G-image beam. Basically, same thing for the CMNs. Okay? So, you have two knobs. The first knob, like the small handle, is the one that is the one on top. It's the smaller and it's the one that is going to give you the right to left axis movement of the probe. The second handle or the biggest handle, which is underneath the small one, is the one that is going to allow you to do anti-flexion or retroflexion. And then you have the possibility of lock or unlock the movements of the probe. The G-machine has an extra knob. Here we have a lateral two knobs for increasing and decreasing your angle. And the G has an extra knob in the middle that can actually make you jump from 0 to 90 degrees in your angle. So, probe maintenance. It is recommended to use protective covers as we use for the electrical connector and for the tip of the probe. We need to check before we put the probe in for brakes, fissures or stroding wires because there is a risk of electrical safety. We need to avoid exaggerate flexion of the tip of the probe because we can actually do damage to the stomach and then we will show you some examples of that afterwards. You need to use infection control after the use and we will go through all the phases. And you need to do an electrical safety if you see any fissure or any brakes or stroding wires. It is recommended to keep a mountaineer in slow book for each TE probe. So, what are the most common things that we can find when there is a rupture of the equipment? So, those are examples. So, as you can see here, there are some brakes, there are some fissures, there are some not stroding wires but cracks and all these needs to be checked before introducing the probe into the patient. And if we exaggerate the flexion, the tip of the probe. So, this is the most usual thing that we can see and those are safety issues because with time this cover will actually get damaged and erosion and then you can actually have an electrical issue here. So, we are going to talk about infection control now. So, once the probe is used, you need to sterilize the probe. So, how are we going to do that? So, we are going to talk a little bit about different options like at TGH, what we do is we drop our probe at the CPD drop-in station. Once it's there, what we use is hydroxyl peroxide 0.5% wipes and we use it for the electrical connection. One wipe and a second wipe for the handle and the tip. And we leave it for three minutes to dry. An alternative option to do like a mechanical cleaning of the probe as we did with hydroxyl peroxide is to use 70% isopropyl alcohol like that's what they use at the Royal Heart Institute. Actually, that's from one of the chapters published at the Content and No Multimedia Manual and they specifically clarified that you cannot use the alcohol for the connection between the electrical connector and the handles and neither into the tip of the probe because then the isopropyl alcohol at 70% can actually damage those. So the only parts where we can actually use these kind of solutions is the connector hosing and the control hosing but they don't recommend it to use it in the other parts. So that's why at TGH we actually use hydroxyl peroxide we use a different agent to do the mechanical cleaning. Once the mechanical cleaning is done we put the probe in what we call an automated TGH probe cleaning machine. So what we are going to use for that is a 2.65% glutaral day solution bath and the recommendation is to put the probe there do it during 20 minutes and after 20 minutes is done you need to let it dry and recommend it to put a plastic cap on the distal and put it in the dropping cart ready to be used again. One of the recommendations is to use the earth tank to dry the electrical connector so you are very sure that there is no residual liquid so when you connect the probe you don't have a problem with the probe but the same thing for the knob handle you need to dry it with the electrical with the earth tank so you are sure that there is no residual glutaral day after the automated cleaning. So another option if you don't have a machine for an automated TGH probe cleaning so it's what they use for example the Morvell Harden Institute the hose and the tip of the TGH probe and they leave it at 2% glutaral day solution bath for 20 to 30 minutes so what's the importance of doing those 20 minutes and can we cut it if we are in an emergency and we need the probe so the recommendation again is when you actually put the probe under a glutaral day disposition so the pathogen destruction is going to happen as follows like in the first minute all the bacteria are gone in two minutes you have a 100% sterile solution in two minutes you will kill HIV and enteroviruses and you need up to 5 minutes to kill your HIV virus and you need a maximum of 10 minutes to get like a very lower type of mycoactamint tuberculosis so that's why it's so important to actually keep it for 20 minutes so you are sure that you have a complete sterile probe so we have talked about indications contraindications and infection control after the probe would use but then we need to talk about the safety so safety how do we insert a probe how should we use like a TGH probe so we don't damage the patient so the recommendations and again this is well well well described in the 2013 American Society of Eccles guidelines for a comprehensive TGH study which they recommend to insert the probe in the unlock position so you need to be sure that the probe is in the unlock position the bite block is actually you pass it through the hose but you don't put it in the mouth only after the insertion why because if you put it in the mouth you can put it in the back of the throat and then you can make damage to the tongue or make the probe to be more difficult to insert so the recommendation is one the probe has actually passed and it's in the suffagus then you actually put the bite block into the mouth to prevent biting from the patient ok always advance the probe in an neutral position with a little with a slight underflection of the probe when you are actually passing the test ok, prevent this large amount of endotracheal tube when the patient is intubated obviously and the recommendation is doing this maneuver which consists in lifting anteriorly and causally demandable in case that that's difficult the laryngoscope can actually facilitate the insertion and in many centers what they recommend is at the same time that you the laryngoscopy you put the endotracheal tube and immediately later when you check the endotracheal tube the solution you just put the T probe in ok so what are the risk of complications when we actually use TE so the global, the average risk is 0.2% which is extremely low and it's something that we need to consider so what is the most important part and I think the major morbidity it comes from the suffageal perforation and we are talking of TE of 0 up to 0.3% ok, you have major morbidity and major bleeding and we are talking for interpretive echo for a major morbidity between 0 to 1.2 and mortality is actually 0% in interpretive echo which I think there are excellent safety numbers for our studies so what can happen, what can go wrong so we talk about the complications that's what can go wrong you can have a buckling during the TE insertion and there are many ways of actually doing damage to the suffageal so if that happens you have trouble to pull up the TE probe and you are not able to do what they recommend to advance the probe with the retroflexion back to the straight position don't try to come back when you are still retroflexing or anti-flexing the probe because then you can damage, so you advance it forward to the stomach in the straight position and then you pull it back and normally you have a higher success of actually removing the probe without causing any damage perfect, so let's talk now about the biological effects of the ultrasound on the human body so the biological effects are divided into thermal which is going to be dependent on your intensity of the ultrasound and non-thermal we should have a mechanical or direct effect which is called a radiation force and cavitation cavitation and intensity are the three main things that are going to cause problems in the body so we are going to start talking about the thermal bio effects so with ultrasound the increasing temperature is absorbed and converted into heat by the body an excessive temperature increase creates toxic stress in mammalian systems so that is going to be completely dependent into the direction of the exposure, the type of tissue that is exposed the cellular proliferation rate on the mucosa that is exposed and the potential for regeneration in this area so as per today the probability of an adverse biological effect increases both with saturation and magnitude of the temperature and we are going to explain that in a second so the thermal bio effect is the most important in terms of the effects much more than the non-thermal so there have never been any health related problems associated with it but I think it is important to understand how that works so TC is the duration of exposure in two minutes and it is also considered the critical time so to calculate the critical time that may happen between 39 and 43 degrees the formula is 4 to the 43 minus T which is the thermal elevation to make an example of that the temperature of the probe is 39 degrees we have 43 minus 39 so that will give you like 4 elevators to the 456 minutes that will be affecting the tissues on the opposite side is your probe is at 43 degrees so that will give you only 4 to the 0 which is 1 will give you 1 single minute so that is when your probe gets too warm and it goes to 43 you will see a message in the screen saying the probe is going to go to automatic auto cooling which is the temperature by itself and the recommendation is to stop to do the ultrasound until the probe actually cools down so the rate of increasing temperature it comes from that formula where the T is going to be the thermal elevation that we have already discussed previously where alpha is the absorption coefficient of the tissue for a given frequency and I will show you the numerator as in the intensity of the ultrasound exposure and that is what is important from that formula you don't need to remember the formula itself but you need to know that the intensity of an ultrasound exposure is normally measured like in millivolts per centimeter to the square or volts per centimeter to the square and it is going to be placed in the screen of your T machine when you are using pulse width opener or continuous width opener the recommendation is as per the FDA to limit the pulse width opener to 720 millivolts per centimeter to the square, the CV is the specific heat capacity of the tissue so the important part that you need to remember here is the intensity of the ultrasound exposure should be limited to 720 and anything above 200 is why it can start to actually create a thermal wire effect so how do we measure that so there is something called the thermal index or the thermal index or TI and this is the indicator of probability of cavitation so this thermal effect is going to condition a non-termal effect which is the cavitation which we will talk in the future in the presentation so it is the predictor of maximum temperature increase and it is the potential for the ultrasound heating related to an average intensity and it is going to be indicated during the Doppler if you are just input with Doppler, color for Doppler or continuous width Doppler the normal value is less than 1.9 the formula is Wp divided by Wdeg so Wp is the relevant acoustic power at the depth of interest and Wdeg is the estimated power necessary to rise the tissue equilibrium temperature one single degree so this thermal index is divided into soft tissue, bone and cranial bone so intensity is important to actually talk a little bit more about the ultrasound intensity as we were mentioning before it can be measured in watts per centimeter to the square or milliwatts per centimeter to the square the intensity can be measured in average or peak intensity and there are three different kinds of intensity where the intensity is going to be different which is the spatial, the temporal and the pulse so when we talk about spatial intensity that means that the intensity in an ultrasound being is going to be different in a certain part of the space or in a certain distance the temporal and it can be measured as spatial intensity, it can be average or it can be peak and it's during the whole time and it's during the pulse duration while we are transmitting and when we are receiving the ultrasound and it can be average or it can be peak and the pulse intensity is the one that is measured only during the transmitting time which is the pulse time and it can be average and peak to understand those concepts better spatial considerations when we talk about spatial intensity we have that the ultrasound beam have different intensities at different depths as you can see here there might start a lot of intensity as soon as it goes deeper it actually fades away, it depends on the type of ultrasound beam the ultrasound beam have a different intensity from side to side locations too and in particular depth the center of the ultrasound beam is more intense than the Hs so those are the spatial considerations but we are actually measuring spatial intensity and this can be average or peak we are talking about temporal intensity what you need to remember is that temporal peak or TP intensity is the maximum intensity and you see here IM is the most intense half cycle in the pulse ok when you are measuring temporal average or TA intensity is measured both during the transmitting time and the receiving time when for the TP it is just at the maximum and the pulse intensity or PA intensity which is only measured during the transmitting time ok so after those explanations how do we quantify intensity which one is bigger, which one is lower so I think the most important part that you need to understand here is that the peak intensity is always going to be above the average intensity the spatial intensity is always going to be the spatial intensity is always going to be above your your temporal ok so what we have here is spatial peak, temporal peak, both of them are peak they are going to be they are going to be always higher than your spatial average and your temporal average ok so the second thing that you need to know is your temporal intensity is always going to be above your pulse intensity ok because it's during the both times as we were mentioning before so when we are doing that the only important thing to remember is when you are using continuous with Doppler your temporal average is going to equal to your pulse average because during continuous with Doppler you have a continuous with Doppler as the word it says it's not a pulse, it goes up and down it goes up and down and the continuous is constantly the same the spatial peak intensity temporal average intensity is going to equal your spatial peak intensity to your pulse average intensity ok so that's the only thing so your temporal average is going to equal to your peak average ok the most relevant intensity with respect to the tissue heating which the FDA is limited at 720 millivolts per centimeter to the square something that they know to ask in the exam is the spatial peak temporal average and why they are going to catch you here because the highest intensity is the spatial peak temporal peak but the most relevant intensity is the spatial peak temporal average I like to put that in a to compare with a ventilatory issue so which pressure is more important in a ventilator your peak airway pressures or your plateau airway pressures sustained during time so that's exactly the same so spatial peak temporal average is the highest exposure average of a period of exposure and it's the most relevant intensity and it's limited by the FDA to 720 millivolts per centimeter to the square ok then I think it's important to mention too that the spatial peak pulse average is the average pulse intensity at an spatial location of maximum intensity ok I think those are the most important things that we need to remember there is another concept that normally they can actually ask is frequent but sometimes there are some questions that have been asked about that it's what's the duty factor which is the relationship between intensities with time it's unit less and it goes from 0 to 1 choose the relationship of the intensities with respect to time that's the duty factor ok so remember spatial peak temporal peak is the highest intensities of all spatial average temporal average is the smallest intensity of all and spatial peak temporal average is the most relevant intensity with respect to tissue heating so ok we talk about thermal bio-effects now we are going to talk about the first one of the non-termal bio-effects which is called radiation force which is a mechanical effect or a direct effect so this is exerted by the sun beam on the tissues the particles are pushed away from the transducer and when the particles are pushed away from the transducer there is an acoustic extreme that is generated on the fluids ok so this will produce stresses and an extreme of the fluids distorting the biological structures that's what is called radiation force it's non-termal and it's a bio-effect the second non-termal bio-effect is cavitation they love to ask about that ok so what is cavitation? cavitation is an oscillation of vibration of gas filled bodies when exposed to the ultrason beam there is a huge wave of the ultrason beam so you have a rudder fraction and compression of the bubbles also they can refer to the bubbles as gaseous nuclei ok so the micro bubbles resonate and when they resonate they resonate at a frequency so this frequency is f0 which is calculated at 3260 divided by r0 which is the micro bubbles radius in micro means ok the gas bubbles form with the oscillating or vibration and then they grow until they reach a critical size and then they collapse that's what cavitation is about so how are we going to measure cavitation? remember that we talked about thermal index to measure thermal bio-effect so the thermal index because it's a non-termal is going to be the cavitation effect related to the peak pressure and you will see that on your screen when you are doing 2D echo we will see your thermal index when you are using continuous width Doppler push width of the colorful Doppler when you are just using your 2D images you will see the higher fraction pressure divided by the square root of the frequency ok which means the higher the frequency the lower is going to be your mechanical index which makes sense because the higher the frequency the less that the ultrason is going to penetrate the tissue the lower the frequency the more that is going to penetrate the same thing for the peak by the fraction pressure the higher the fraction pressure so the mechanical index is going to be higher so the mechanical index increase with lower frequency and a stronger sound waves lower frequency so the lower the frequency is in the denominator the higher the mechanical index the peak by the fraction pressure is higher which means stronger sound waves so you can get more mechanical index the mechanical index reflects the amount of contrast harmonics that are produced you have low mechanical index higher mechanical index and highest mechanical index point is below 0.1 which is almost minimal you have no harmonics you have packet scatter you have a linear behavior of the bubbles and normally is associated with higher frequency sounds so this is going to be a surface probe the one that we use for doing central lines when you have a higher mechanical index it's up to 1 you have some harmonic effects you have some resonance you start to have non-linear behavior and it's related with lower frequency probes we are talking about probes that are between 5 and 3 MHz when you have the highest mechanical index you have below 3 or 2 MHz you create a mechanical index of more than 1 you have the strongest harmonic you start to have bubble disruption and you have an extreme non-linear behavior of the bubbles and they are related to the lowest frequency probes so when we are talking about cavitation we have two forms of cavitation we have stable and we have trenching cavitation it's important to differentiate the nomenclature here because when you say transient is inertial or normal when they say normal cavitation that doesn't mean stable that means transient or inertial ok that's important because it's easy to get actually confused with that when we talk about the stable cavitation stable cavitation is at lower mechanical index levels so the bubbles expand and contract but don't abreast the bubbles oscillates with the sound bin they can be related to this stable cavitation some mechanical damage, they can be membrane rupture and cell lysis at in vitro levels ok when we talk about transient or normal, inertial so it's when you have higher levels of mechanical index which produces as you can remember it's non-linear behavior of the bubbles rapid expansion and collapse the bubbles start to burst and they can lead to colosal temperature and shock waves it's not clinically significant ok so cavitation, what can cavitation do it has been described long emeralds in adults and it has a special important effect into fetus so when we are doing the ultrasound for the fetus it's something that doesn't apply to TE but you need to remember that ok just to remember a little bit when do we have increased mechanical index or increased thermal index when you are using your Doppler modes more than when you are using 2D when you have low frequency flow when you have a reduced scan area so you are concentrating more your energy when you use a deep focus because then you need to reduce a lot your frequency to be able to penetrate the tissues ok so when you go down down down to the screen with the focus that is going to concentrate in that area your mechanical index and thermal index when the power that you are using from the ultrasound is higher and when the big fraction is high when the ultrasound beam the power of the ultrasound beam is higher ok so we have talked about biological effects thermal and non-termal we are going to talk about electrical safety ok so you need to remember that the electrical energy converts into thermal energy but not sonic energy ok what happened with that is whenever we have like a rupture of the membrane of the transducer so the electrical energy instead of converting into sonic energy is going to be converted into thermal energy and this electrical harm of thermal injury with ultrasound can happen but the risk of happening is very low so that's why it's so important to look for erosion, perforation or any cracks ok before introducing the probe as an example when we are doing radiofrequency for atrial fibrillation there has been report of esophageal burns during the radiofrequency and fistula or perforation so that's why during those procedures the tea should be removed during the ablation I hope you have enjoyed the lecture and we will see you with the multi-choice questions the next week, thank you