(1)
Hôpital Ambroise Paré Service de Réanimation Médicale, Boulogne (Paris-West University), France
Electronic supplementary material
The online version of this chapter (doi:10.1007/978-3-319-15371-1_31) contains supplementary material, which is available to authorized users.
In cardiac arrest, the SESAME-protocol proposes to scan first the lung for two major targets: pneumothorax and clearance for fluid therapy. This information can be obtained in less than 5 s, i.e., a minimal hindrance in the course of resuscitation.
The SESAME-protocol then scans the lower femoral veins and the belly (first if trauma), for detecting pulmonary embolism or massive bleeding.
Then a pericardial tamponade is sought for.
Cardiac causes then follow, in position 5.
Our small, compact ultrasound unit (with the 5 MHz microconvex probe) allows for whole body exploration. How does it work in practice, considering the ultimate emergency: cardiac arrest?
The Concept of Ultrasound in Cardiac Arrest or Imminent Cardiac Arrest, Preliminary Notes
No need to write that we deal here with the highest degree of skill, responsibilities, and emotion (Fig. 31.1). Slight warning: the diagnosis of a cardiac arrest is usually easy and does not require ultrasound. The SESAME-protocol should not be used by doctors knowing the cause of this given cardiac arrest. It is mainly devoted to the arrest of unknown origin, assuming that we have no clinical clue for orientation. It is also devoted to the young intensivist not sure to give his or her best. The author is not young but uses this protocol in almost all cases. The word “usually,” written 8 lines above, becomes obsolete with the use of ultrasound.
Fig. 31.1
Cardiac sludge. In this subcostal view, all chambers have echoic homogeneous content. This sludge pattern is the result of cardiac arrest (hypoxic asystole in a chronic lung disease). The chambers will become normally anechoic after the recovery of a spontaneous cardiac activity (VD right ventricle, VG left ventricle)
Cardiac arrest and imminence of cardiac arrest have many common causes. The SESAME-protocol was initially built for extremely severe shocks with imminence of cardiac arrest, but rapidly extended to cardiac arrest. To consider both together allows making the thinnest possible textbook. Few subtleties are not significant enough for changing the spirit.
The best medicine is to anticipate cardiac arrest, by detecting the reversible causes. In the dark ages, these were usual errors in diagnosis, yielding so many avoidable deaths in the night of admission – before the era of visual medicine. The concept of the SESAME-protocol was to find the compromise combining the most frequent situations, the most easy to diagnose using ultrasound, and the most accessible to immediate management – apart from shockable causes. Obstructive causes (pneumothorax, pericardial tamponade, pulmonary embolism) and hypovolemic causes (hemorrhage, etc.) are the most easy to manage. Pneumothorax is probably the best example. In other causes, ultrasound plays a modest role: myocardial infarction, hypoxia (no need for ultrasound for administrating oxygen in a cardiac arrest), hypothermia, toxins, etc.
All settings are considered together (home, trauma, ward, ICU, rich or poor institutions, war settings, etc., resulting in a thin textbook, etc.). In critical situations, the signs are usually blatant (apart from massive pulmonary embolism with no low femoral DVT nor cardiac window, since only subtle signs must be sought for).
Holistic ultrasound will be exploited here to its best, resulting in a really fast protocol where each second is devoted to a specific task. Our daily 26-year work aimed at optimizing each step. We invite to follow a sequential order.
SESAME-Protocol: Another Fast Protocol
Our sequential echographic screening assesses the mechanism or origin of a shock of indistinct cause. SESAMOOSIC was a long abbreviation that we shortened in the convenient SESAME-Protocol. Our personal examination regarding shock using adapted sonography indicating origin or nature (yes, PERSUASIOON) is rather for those who would prefer tortuous acronyms.
From its own words (see the italic O of the native label), one of the main peculiarities of the SESAME-protocol is to take into account the mechanism or the cause of the drama. The user permanently travels from cause to mechanism, according to what comes first to the screen. Finding blood in the abdomen (suggesting hypovolemic cause), or hypercontractile heart (suggesting mechanism of hypovolemia), or again the A-profile, all go to the same action: immediate fluid therapy. There is no time for academic considerations.
Time for scanning both lungs is usually 10 s. Then detecting leg venous thrombosis, abdominal fluid, or pericardial fluid can be done during cardiac compressions (24 more seconds). Then 12 s are devoted to the heart, with the necessity to stop the compressions.
Cardiac Arrest: Time for Technical Considerations
The SESAME-protocol assesses the lung (far) before the heart, because in 5 s pneumothorax can be discounted and clearance is given for fluid therapy. This apparently futile property upsets the choice of equipment. This textbook will reflect our direct positioning without compromise (Anecdotal Note 1).
Nowadays machines are often laptops with three probes, each one having devoted applications (vascular, cardiac, and abdominal). Multiple filters, harmonic modes, and various facilities allow image refinements. Is it an advantage or a hindrance in critical ultrasound, especially cardiac arrest?
This chapter is an opportunity to remind that the unit that allowed us to define critical ultrasound was the perfectly suitable ADR-4000 from 1982, then the Hitachi-405 since 1992 (updated 2008), which was slightly superior. Since this is so important, we repeat it here briefly, with critical adaptations, the best of Chaps. 2 and 3, on the seven points that make the difference.
1.
Size. Each saved centimeter is critical. Our machine is 32 cm wide on the cart, i.e., narrower than laptops. This size plus the wheels allow to bring the unit quicker at the bedside of busy settings (ICU, OR, ER, etc.). Imagine we organize a race, each one would take his preferred machine (always fixed on carts of course), all in the same line. At the start, we may see a beautiful mess, with all these large machines running for avoiding the hospital obstacles. A steeple-chase. Who will be the winner? The slimmest machine, regardless laptop or not. Pocket machines? Read the last FAQ, below.
2.
Start up time. Each second is critical. Our unit starts up in 7 s. In machines with longer start up time (from 30″ to 3′), there is nothing to do but wait. We don’t care to have informatic programs – we need an immediate access.
3.
The probe. Which probe first if pneumothorax, bleeding, and tamponade are all possible (trauma)? Respectively (in this order if the user wishes to follow the SESAME-protocol), the linear then the abdominal and then the cardiac? This probe swapping is time-consuming (not to forget probe/cable disinfection, here theoretical, usually a critical point). The SESAME-protocol skips this chancy guessing game by using a universal microconvex probe. It is a high-level compromise allowing in a few seconds, a lung-vessel-abdomen-pericardium-heart assessment exploiting its 0.6–17-cm range (see Chap. 3). Its shape allows insertion at any site, narrow or large, linear or not.
4.
Simple technology, plus a life-saving detail. It is permanently configured with the setting of cardiac arrest, which is the same used for everyday applications (venous line insertion, check for bladder distension, etc.). We have no setting “LUNG.” Our setting is “critical ultrasound,” or “SESAME,” or “zero filter,” or again, “CEURF.” There is no change to do for being immediately operational. No destructive filter, no confusing time lag, no harmonics that alter the artifact detection. Complex keyboards, a hindrance for novices, are a hindrance for all in critical, stressing settings. Remember we advocated three buttons for practicing critical ultrasound. Not a lot, yet this is too much in cardiac arrest. Gain? When the unit starts up, it is at the optimal setting. B/M mode? It will not be touched, this is why we advise to get accustomed to recognizing immediate, real-time lung sliding. Depth? A special paragraph for this critical detail.
The depth: we have fixed a default value, at start-up, of 85 mm. This range is the compromise that allows us to see with maximal relative accuracy those targets: the pleural line, the Merlin’s space, the lower femoral vein, the peritoneum, most GI tract, and the pericardium in most cases. If we have to arrive to the heart (Step 5), time may be devoted to push the button up to 140 mm. This setting has been worked out for saving an optimal number of neurons. Everyone can define a different setting (child setting, etc.), just think that depth is time.
We insert in this section our contact product, Ecolight®, since its use (apart from resulting in a clean discipline) warrants a fast protocol. It saves precious time – with Ecolight®, time for changing a region of interest (lung, veins, belly, pericardium, etc.) is less than 1 s. Read also at the cardiac step, another unexpected advantage.
5.
Compact design. It is flat, cleanable.
6.
Image quality. Just see the figures of this textbook. No time to play guesses here, with suboptimal equipment.
7.
Cost. Its low cost was an opportunity for most patients on Earth since 1992 and even before: the year 1982 was the time for the revolution.
Each detail interacts with others. Our single probe lies on top, not laterally, a detail that saves lateral width: one example among dozens of holistic ultrasound. Some manufacturers begin to build machines inspired by this 1992 technology.
Unexpected limitations can suddenly appear at any step, potentialized by the extreme stress. An issue is the permanent risk to face unsuitable cardiac windows. Several probes make cables inextricably mixed. Nervously pulling the cable results in drawing the knots tighter, etc. Among apparently futile causes, cables lying on the floor favor the risk of a machine tip over when suddenly mobilized. When each of these small (or bigger) difficulties is added to each other, it is maybe wiser, sadly, not to use ultrasound, and do like doctors always did, i.e., working clinically. Ultrasound must save time, not the opposite.
This section was an opportunity to insist again on the interest of our universal probe among others. Repeating and repeating is sometimes worth it.
Practical Progress of a SESAME-Protocol
For simplifying the concept, we consider a cardiac arrest occurring in a hospital. It allows the physician to intubate the patient, and then pilot the resuscitation. One solid help makes the cardiac compressions. One delicate help makes the ventilation. One nurse prepares the drugs, etc. (Technical Note 1). For less than four actors, see Technical Note 2.
It is assumed that the intubation was wisely done, i.e., not inserting a demesurate number of meters of endotracheal tube within the thorax. This is important first because ventilating both lungs allows correct oxygenation. If there is no cardiac pulsation, there is no lung pulse, and the one-lung intubation would simulate a pneumothorax, etc. A reasonable length is inserted (3 cm after the vocal cords is highly sufficient). Common sense is more useful than ultrasound here. Ultrasound-assisted ABCDE? Read Anecdotal Note 2.
We assume all details not pertaining to ultrasound (sternal punch, check for airway patency, etc.) are covered as usual.
Now, we can manage this cardiac arrest. Figure 31.2 indicates the optimal timing, done with quite no interruption of cardiac massage.
Fig. 31.2
The SESAME-protocol. A logical order suggested for assessing cardiac arrest or extreme circulatory failure. SESAME-protocol in a kind of explicit decision tree. Note the quasi-absence of dichotomy: the causes are sought for sequentially, mingling frequency, easiness of ultrasound detection, and possibility of active therapy. Steps 1, 2, 3, 4 are devoted to highly reversible causes: pneumothorax, pulmonary embolism, hypovolemia, and pericardial tamponade. Step 5, more expert, more chancy (depending on favorable windows), asks for the interruption of cardiac compressions. This figure indicates the optimal timing in the best conditions (patient in bed, readily accessible regions of interest), the type of probe used for each step (i.e., here, for all steps), and the depth chosen. The timing includes any change of region of interest, expedited using Ecolight®
The Lung: First Step of the SESAME-Protocol
Here is no time for politeness (read Anecdotal Note 3). In spite of what was written since ever in the stone regarding lung ultrasound [1], the SESAME-protocol not only includes the lung, but also, and without any complex, begins with the lung. We have all reasons, diagnostic, therapeutic, technical. To begin with the lung allows to benefit from a series of seven providential features:
1.
A highly reversible cause of cardiac arrest is detected: pneumothorax.
2.
Finding an A-profile makes half of the diagnosis of pulmonary embolism, following the rules of the BLUE-protocol [2]. The diagnosis will be confirmed just after by the venous step (or 24 s later at the cardiac step – window permitting).
3.
4.
Lung windows are always `“generous”: no need for chancy search, like in echocardiography. The correct window is obtained in 1 s.
5.
A pneumothorax able to generate a cardiac arrest is substantial: one point is sufficient.
6.
In cardiac arrest, the patient breathes very quietly. This makes the perfect conditions for an optimized detection. No dyspnea, no Keye’s sign, no pseudo-A′-profile here: ultrasound is a providence.
7.
All this information is obtained in less than 5 s, i.e., a minimal hindrance in the course of resuscitation.
We check at the lower BLUE-point, roughly, while the compressor’s hands are positioned on site, ready to work (Technical Note 3). If a pneumothorax is suspected, the CEURF has described some fast solutions. Searching for a lung point may cost time. If decided, it should be done first very posteriorly. Finding (especially in bilateral cases) an extended (anterolateral) A′-profile, detecting just lung sliding posteriorly is a nonacademic makeshift, a common sense maneuver instead of the pathognomonic lung point. The Australian variant can be perfectly used here (see Chap. 27 on pneumothorax): we can consider an A′-profile as a pneumothorax in the case there is a strong clinical argument. The patient is here in cardiac arrest: do we need a stronger clinical argument? Read Anecdotal Note 4. We strengthen this suspicion by here just sounding the thorax by percussion. At this step (cardiac arrest with A′-profile), the slightest tympanism at the suspected side makes the decision. Manually sounding the thorax before ultrasound would be a loss of time each time there is no pneumothorax (and is not a 100 % easy sign in routine medicine). When the Australian variant is positive, the hands of the cardiac compression begin or resume their work, time for finding any large needle, and saving a life.
If the first scanning shows disseminated lung rockets, fluid therapy will not be the immediate option. It means likely that the problem is not related to a low preload. Cardiac causes are usually on focus. The lungs are wet and a fluid therapy may hinder optimal oxygenation (Technical Note 4).
In trauma (mainly frontal mechanism with lung contusion), anterior lung rockets are expected (in the absence of pneumothorax).
No pneumothorax? The probe comes to the femoral veins.
The Veins: Second Step of the SESAME-Protocol
Compressions Begin (or Are Resumed)
A deep venous thrombosis found in a patient with cardiac arrest is quite diagnostic for pulmonary embolism, following the rules of the BLUE-protocol, where the specificity is 99 %.
In the mind of radiologists or vascular physicians, venous scanning is a comprehensive, long work. Here, we use the technique of the BLUE-protocol adapted to the extreme emergency. By applying the probe at the V-point (lower femoral vein), the operator has the best compromise between the following:
Sensitivity: almost half cases with massive embolism had a lower femoral venous thrombosis, twice as many as the common femoral vein (still under submission). Likewise, scanning the inferior caval vein would be a loss of time: here, the likeliness to still see floating iliocaval thrombosis is near zero. In our series of massive pulmonary embolism under submission, there is no inferior caval location, and we don’t devote energy (in the BLUE-protocol) or time (in the SESAME-protocol).Related posts:
The Excluded Patients of the BLUE-Protocol: Who Are They? Did Their Exclusion Limit Its Value?
The BLUE-Protocol and the Diagnosis of Pneumonia
Glossary
The Ultrasound Approach of an Acute Respiratory Failure: The BLUE-Protocol
Suggestion for Classifying Air Artifacts
Which Equipment for the BLUE-Protocol 2. The Probe
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