Considerations that poor CPR quality with frequent interruptions may entail low survival rates [25,26], as previously stated, led to the development of feedback devices that are designed to measure important CPR quality parameters (i.e., compression depth, relief, frequency, and hands-off time) and give real-time audio (clickers for tactile feedback) or audiovisual feedback. This enables life support providers to continuously monitor and, when appropriate, to self-adjust their external chest compressions in real-time. Furthermore, most systems allow the users to retrospectively analyze the performance for educational purposes. Therefore, real-time feedback devices are expected to improve CPR quality and possibly patient survival [27].

Several trials report partially contradictory or ambivalent results concerning the effect of real-time feedback systems on CPR quality and patient outcome [27,28]. In addition to several observational studies, mainly from simulated training scenarios, only two RCTs could be identified. An individualized RCT and its secondary analysis evaluating an audio-only feedback device in a hospital setting found better adherence to resuscitation guidelines, as well as significantly higher rates of ROSC and survival until intensive care unit (ICU) and hospital discharge [29,30]. A large cluster RCT evaluating an audiovisual device in an out-of-hospital setting confirms the findings regarding improved CPR quality, but this was not associated with improved survival rates [31]. This result calls into question the previously assumed clinical relevance of improved chest compressions.

There seems to be sufficient objective evidence that the application of real-time audio or audiovisual feedback devices contributes to an improvement of chest compression quality and continuity, as laid down in resuscitation guidelines. In order to either confirm or refute the hypothesis that improved chest compressions actually lead to higher survival rates with favorable neurological outcomes, further well-designed, sufficiently powered, and properly conducted studies are necessary.

Nevertheless, currently, valid guidelines recommend the use of real-time audiovisual feedback devices in order to improve CPR quality as a part of a comprehensive quality improvement program [11,32].

A large RCT, the ASPIRE trial was terminated prematurely by the data and safety monitoring board, after there was—despite similar survival rates at 4 h after the incident—a trend to impaired survival until hospital discharge and neurologic state [33]. Despite slightly distinctive definitions of ROSC, none of the other studies revealed any statistically significant different rates of ROSC at any time or sustaining ROSC until hospital admission, respectively. The CIRC trial, an RCT that compares an automated mCPR device utilizing a load-distributing band to conventional manual CPR, found a slightly diminished rate of sustaining ROSC (odds ratio (OR) 0.84, 95% confidence interval (CI) 0.73–0.96) and survival after 24 h (OR 0.86, 95% CI 0.74–0.998) in the mCPR group. This observation is recouped during the stay in the hospital, as the rate of survival until hospital discharge (OR 0.89, 95% CI 0.72–1.10) and neurologic state at discharge according to the modified Rankin Scale (mRS) (OR 0.80, 95% CI 0.47–1.37) do not show any statistically significant differences [34]. Two other well-conducted multi-center RCTs, the LINC trial [35] and the PARAMEDIC trial [36], found equal survival rates until hospital discharge. In the latter, this was associated with a slightly but significantly worse neurologic outcome in the intervention group receiving automated mechanical chest compressions through a vertical piston device. Adjusted OR for the risk of favorable neurologic outcome (defined as CPC 1–2) was 0.72 (95% CI 0.52–0.99) [36]. Apart from these exceptions, no statistically significant differences in survival rates and neurological outcomes were observed in any of the large RCTs [34,35,36,37]. In the as-treated analysis, the MECCA investigators found improved survival rates compared to conventional manual CPR, if the automated mCPR device utilizing a vertical piston was attached “early” during the course, viz., before moving the patient to the ambulance [37]. In all these studies, it is of key importance to consider that the results and, thereby, the conclusions of superiority or inferiority of any technique mainly depend on the quality of conventional manual CPR delivered in the respective control groups [38,39].

The observations regarding the importance of time correspond with observations from a retrospective registry analysis, where a higher rate of ROSC was found in the mechanical CPR groups, which is mainly attributable to lower risk factors among the population within this group. Compared with the predicted rate of ROSC (the ROSC after cardiac arrest (RACA) score), patients in the load-distributing band group achieved ROSC significantly more frequently (predicted 46.6%; achieved 57.1%, 95% CI 49.5–64.5%), while patients in the mechanical piston group (predicted 43.4%; achieved 46.5%, 95% CI 38.4–54.7%) and manual CPR group (predicted 39.9%; achieved 40.1%; 95% CI 39.2–41.1) only fulfilled the predicted outcome. Adjusted for epidemiologic and therapeutic factors, OR for ROSC was 1.70 (95% CI 1.12–2.57) for the load-distributing band system and 1.66 (95% CI 1.09–2.51) for the mechanical piston system [40].

The installation of automated mCPR devices may delay the time until the first defibrillation, depending on which source is consulted, for a period of up to 2.1 min [33,34,35,38]. A Cochrane review suggests that these negative impacts on CPR quality, namely lag-times until the application of the device with increased hands-off time and delay of the first defibrillation in shockable rhythms, may negate “any physiologic benefit observed in preclinical studies” [39]. Nevertheless, defibrillation is feasible and safe during ongoing automated mechanical chest compressions and, thereby, reduces the hands-off time during the later course [5,35].

Further data regarding secondary outcomes, such as long-term survival (e.g., after 1, 3, 6, or 12 months) or CPR quality surrogates (e.g., compression depth and frequency, hands-off time, injuries, blood pressure, coronary or cerebral perfusion pressures, respiratory, metabolic, and other laboratory parameters) show heterogeneous and, in parts, contradictory results. The later the endpoints, the slighter the difference between mechanical and manual CPR outcomes—a frequent observation within longitudinal resuscitation studies [38,39,44,45]. Trauma due to chest compression may occur both after conventional manual and automated mCPR in the same frequency, but the injury patterns seem to differ. Patients who received conventional manual chest compressions typically show anterior rib fractures, sternum fractures, unshaped midline chest abrasions along the sternum, visceral bleeding, and retrosternal hematoma. In contrast, patients who received automated mechanical chest compressions show posterior rib fractures, vertebral fractures, shaped skin abrasions along the anterolateral chest and shoulder, visceral bleeding including liver and splenic lacerations, and retroperitoneal hematoma [46,47,48,49].

Automated mCPR cannot reverse any cause of cardiac arrest, nor does it lead to higher survival rates compared to manual CPR. Hence, manual chest compression should be the standard technique, but under special circumstances and in particular fields of application, the devices may provide effective and safe chest compressions until an adequate health care facility is reached, where the definitive treatment can be performed. Thus, these systems may be beneficial as a bridge to treatment tool or as a bridge to decision on further treatment, and may be considered especially during prolonged resuscitation attempts. This might arise under specific conditions, such as, for example, sustaining ventricular fibrillation (VF) [50] or hypothermic cardiac arrest [50,51,52,53,54], patient transportation [5,55,56,57], diagnostics, such as computed tomography (CT) [5,58,59,60] (not chest X-rays [61]), and interventions, such as percutaneous coronary intervention (PCI) [5,58,62], fibrinolysis [60,63], dialysis [54], extra-corporeal membrane oxygenation (ECMO) [5], transcatheter aortic valve implantation (TAVI) [64], surgery [65,66], or organ preservation until retrieval [5,67]. On the other hand, after the implementation of mechanical CPR devices in a German EMS system, a dramatic increase in transportation with ongoing CPR, even for patients with unfavorable prognoses, has been observed [68].

Thus, appropriate patients with potentially reversible and, therefore, treatable causes of cardiac arrest should be carefully identified and selected, as they might profit from transportation to a suitable hospital under ongoing automated mCPR with clear therapeutic approaches [54]. This interpretation is consistent with the manufacturers’ original intention, as laid down in the 1979 US Food and Drug Administration (FDA) classification report: “(…) the device is not designed to replace manual CPR. The literature seems to recommend it for certain situations (…)” [69]. Currently, valid guidelines recommend trained teams that are familiar with the device to consider automated mCPR “only if high-quality manual chest compression is not practical or compromises provider safety” [5], and under special circumstances, such as hypothermia, metabolic disorders, low cardiac output state, obesity, the need of prolonged transportation, difficult terrain, and restricted space conditions, for example, helicopter flights due to a limited cabin size [54].

As previously stated, it is necessary to keep the low-flow time during CPR as short as possible. In the setting of an OHCA, it is essential to identify patients early who could benefit from an advanced or invasive procedure, such as extra-corporeal life support (ECLS), often synonymously referred to as extra-corporeal CPR (eCPR). As this approach involves a specialized multidisciplinary team, the decision should be made involving all parties.

eCPR has proven to increase the chances of survival with good neurological outcomes in patients with refractory cardiac arrest treated in experienced centers by expert teams. Two randomized controlled trials demonstrated the effect of eCPR and a subsequent invasive diagnostic and treatment strategy, such as PCI. Early invasive treatment is the cornerstone of increased survival in these patients. Bělohlávek et al. demonstrated in a secondary analysis a favorable neurological outcome in 22% of patients who received eCPR, which is the same proportion as patients in the standard-of-care group. Compared with 31.5% in their intervention group, this demonstrates the effect of an early invasive treatment strategy even without eCPR [7]. A smaller phase 2 RCT, the ARREST trial, was stopped early by the DSMB, as superiority exceeded the prespecified monitoring boundary in a planned interim analysis. The survival rate in the eCPR group was significantly higher than in the control group, but the case number was too small to demonstrate benefits in neurological outcomes [70]. In a secondary analysis from the original Prague OHCA trial, Rob et al. found a significantly higher rate of survivors in patients without prehospital ROSC and eCPR compared to standard ACLS. Furthermore, a good neurological outcome (CPC 1 or 2) was only achieved by 1.2% of patients treated with standard ACLS without prehospital ROSC. This compares to 21.7% in the eCPR group and 56.6% when prehospital ROSC was achieved [71]. All studies that are assessing the effect of eCPR in patients with OHCA have a high rate of bystander CPR. Although it should not be limited to this factor, bystander CPR has been shown to be crucial in all OHCA cases [72].

Currently, there is no consensus on when eCPR should be performed. Some studies suggest that the latest decision point should be around 30 min after cardiac arrest [73]. Recent studies in Prague [7] and Denmark [74] showed a beneficial effect in patients with > 30 min of low-flow time. Furthermore, the study by Mørk et al. showed a neurologic intact survival in 20% of the patients receiving eCPR with a low-flow time of >75 min [74]. In contrast, earlier studies have shown no benefit when eCPR was initiated after 60 min of cardiac arrest [73].

As important as the optimal timing of eCPR cannulation are the decision criteria for eCPR initiation. National [75] and international [5,20] guidelines are available to answer this question. Overlapping inclusion criteria are younger age, witnessed arrest, duration of no-flow time <5 min, and time until eCPR initiation <60 min. Further criteria to consider are signs of life under CPR [76], intermittent ROSC or recurrent VF, neuroprotective circumstances, availability of cardiac arrest center with PCI capability, blood gas analysis, known diseases and, if known, the patient’s request. Signs of life under CPR were independently associated with a favorable neurological outcome. In a study analyzing 434 individuals undergoing eCPR, any sign of life before or throughout CPR was associated with an OR for a favorable neurological outcome of 7.35 (95% CI 2.71–19.97). This was further assessed for different types of signs of life, such as gasping, pupillary light reaction, and increased level of consciousness. Those signs had an OR of 1.75 (95% CI 0.95–3.21), 5.86 (95% CI 2.28–15.06), and 4.79 (95% CI 2.16–10.63), respectively. Patients with pulseless electrical activity (PEA) or asystole had a 12% (95% CI 5–25) chance of 30-day survival with CPC 1–2 when any sign of life was present. In contrast, patients without signs of life in PEA or asystole had a 0% (95% CI 0–7%) 30-day survival with CPC 1–2. This effect is also seen in patients with a shockable rhythm, where 23% (95% CI 17–30%) with any sign of life and only 4% (95% CI 1–11%) without any sign of life had a good neurological outcome, respectively [76].

It remains unclear which cannulation strategy is the best for eCPR in OHCA patients. Kashiura et al. demonstrated that patients who underwent eCPR cannulation with both ultrasound guidance and fluoroscopy had an independently associated lower complication rate compared to ultrasound guidance alone (adjusted OR 0.14, p = 0.024). Furthermore, the time until eCPR started was the same in both groups, with a median of 17 min [77].

This compares to a mean cannula insertion time of 22.5 ± 9.9 min when a hybrid cutdown technique is performed by non-surgeons [78]. For all three approaches, failure rates were low with a change to surgical approach in four cases (8%) if ultrasound was the only method used. The overall failure rate for the hybrid approach was as low as 7.4%.

Danial et al. assessed the impact of cannulation techniques in 814 patients. Until November 2016, all patients were cannulated using a surgical approach, while hospital policy changed in November 2016 and a percutaneous approach was used from there on. Using this retrospective data, a propensity score-matched cohort study for cannulation techniques in 532 veno-arterial ECMO patients was performed. Patients were divided into a surgical and percutaneous group, with 266 patients each. Compared to a surgical approach, percutaneous access, performed via doppler ultrasound, had a higher 30-day overall survival rate (63.8% vs. 56.3%, p = 0.034) and more vascular complications after cannula removal (14.7% vs. 3.4%, p < 0.001), which mainly resulted in surgical revision for persistent bleeding. Furthermore, a lower infection rate at the cannulation site was recorded (16.5% vs. 27.8%, p = 0.001) [79].

Especially if a contralateral approach is used, the risk of arterio-arterial or veno-venous cannulation is given; this can be limited with ultrasound guidance.

Similar to automated mCPR, eCPR should not be considered a definitive treatment in cardiac arrest, but as a bridge to decision or bridge to treatment while organ perfusion (particularly cerebral and coronary) is maintained. Moreover, eCPR might have the potential to serve as a bridge to recovery. Again, it is crucial to identify patients with potentially reversible entities of cardiac arrest who might profit from this invasive treatment; for example, therapy-refractory ventricular fibrillation or severe hypothermia. In-depth expertise is essential for the implementation of this measure, which requires comprehensive technical and non-technical skills and correspondingly high case numbers at the institutions providing the training. In addition to human resources, the receiving hospital must also have the equipment and capacity for this highly critical patient population. Moreover, it requires a system with highly skilled care providers, as well as the equipment and capacity necessary to provide adequate continuing care for patients.

In addition, eCPR might also serve as a bridge to donation. Although this should never be the main purpose of initiation, it can be a secondary benefit to others when, despite the best effort, ECMO weaning is not possible or severe brain damage has already occurred.

High-quality chest compression is the cornerstone in the treatment of each cardiac arrest case. The “middle of the chest” has been proven to be an unreliable place when the left ventricle (LV) should be compressed [82,83,84]. One approach would be to continuously assess the capnography waveform and change hand positions based on three pre-defined positions.

As this “blind” approach can be time-consuming and waveform capnography can be impaired due to various circumstances, such as the underlying pathology, echocardiography during CPR is a powerful tool for the detection of the area of maximal compression (AMC), and following the optimization of chest compression.

Although availability can be limited, the TOE probe can be inserted during ongoing chest compressions. Assessment of the AMC is performed in the midoesophageal 4-chamber view (ME4CH) and the midoesophageal long axis (MELAX). As soon as the AMC is identified over the left ventricular outflow tract (LVOT) or the right ventricle (RV) (Video S1), hand positioning should be optimized. Continuous assessment of the AMC is now possible while maintaining high-quality chest compressions.

Blaivas described the performance of TOE under CPR in 2008 with a case series from an emergency department highlighting the benefits of continuous chest compressions while seeking reversible causes that led to cardiac arrest [85].

Hypovolaemia: In traumatic cardiac arrest, hypovolaemia due to exsanguination is one of the most common reversible causes, and invasive therapeutic options are available. In order to enhance certainty before performing invasive interventions, the eFAST protocol can be applied to detect free abdominal or thoracic fluid. Venous congestion during CPR can limit the significance of inferior vena cava (IVC) assessment. Current guidelines state limited knowledge about the use of ultrasound for the detection of hypovolemia in cardiac arrest [5,32].

Thromboembolism: Thrombosis, either cardiac or pulmonary, is one of the most frequent causes of sudden cardiac death. As PE has non-specific clinical signs and symptoms that may lead to PEA, it is crucial to look for specific echocardiographic signs before the patient further deteriorates [87,88]. Therefore, visual assessment should be the main priority, as this can be performed in every setting with a handheld ultrasound device.

In patients with cardiac arrest, RV dilation is a common finding, especially if resuscitation has been ongoing for a prolonged period [89]. This weak association between RV dilation and PE brings a challenge to the table, leaving only reduced possibilities of identifying PE during CPR. Right heart mobile thrombus could be seen during CPR, suggesting the presence of PE [88]. A second finding, deep vein thrombosis (DVT), can be detected in about 30–50% of patients with PE by compression ultrasound [90].

While the need for emergent ultrasound diagnostics is not given in shockable rhythms, it may provide valuable information in peri-arrest situations or following ROSC, if a 12-lead electrocardiogram is inconclusive. Regional wall motion abnormalities can be seen even in patients without significant repolarisation abnormalities.

Tension pneumothorax: Ultrasound is not only faster than conventional chest X-rays or CT—it also offers better sensitivity and specificity than chest X-rays. In addition, it can be performed directly at the site of emergency [91] if the “classical” diagnostic means are uncertain.

Pericardial tamponade: A pericardial effusion was previously considered only a suspected diagnosis in the out-of-hospital setting, which could not be ruled out with certainty. With the increasing availability of portable ultrasound equipment, even users with little experience can answer the question of the presence of a pericardial effusion using the eFAST or FEEL protocol in the field [92].

As previously stated, REBOA is used to control bleeding from non-compressible injuries in critically injured casualties with uncontrolled hemorrhagic shock unresponsive to volume therapy [93]. Depending on the underlying trauma, the balloon occlusion may be deployed either in landing zone I (thoracic and upper abdominal bleeding and aortic dissection) or III (sub-/pelvic or grain bleeding) [94].

As this special issue’s focus is on sudden cardiac death rather than TCA, the application of REBOA in catastrophic bleeding is only briefly mentioned due to historic and didactic reasons. Pertinent literature might be of interest for further reading [93,94,95].

When applied in trauma patients, the aortic occlusion substantially increased blood pressure which was expected to result in increased cerebral and coronary perfusion. Consistently, it is alleged that the REBOA procedure might have an epinephrine-like effect on aortic and subsequently coronary pressures [10]. As previously stated, those are associated with improved rates of ROSC and survival [17]. In order to enhance cardiac and cerebral perfusion pressures during CPR, the REBOA catheter should be placed in landing zone I.

As a matter of fact, the first experimental studies confirmed enhanced coronary and cerebral perfusion after performing the REBOA procedure in a porcine cardiac arrest model [96]. On this occasion, the effects on both perfusion pressures and ROSC are comparable to those achieved from the application of epinephrine [96]. For a long time, merely case reports and observational studies were published reporting that REBOA is feasible and effective in non-trauma cardiac arrest [97,98,99,100,101,102,103,104]. The clinical studies predominantly lack control groups and are limited to surrogate outcomes, but support the physiological considerations on perfusion as previously described [102,103,104,105]. Hence, REBOA is increasingly seen as an adjunct to non-trauma advanced cardiac life support. If performed rapidly by a highly skilled team from an experienced center, enabling a short collapse-to-balloon time, it might serve as a bridge to treatment until PCI or ECMO [106].

In a randomized controlled feasibility study, a team from Heidelberg University Hospital examines the value of a REBOA device in non-trauma cardiac arrest. In addition to its safety and performance, secondary outcome measures and surrogate parameters such as blood pressure, CPR time intervals, and ROSC are of the investigators’ particular interest [NCT05146661]. The currently ongoing multi-center randomized controlled REBOARREST trial is supposed to provide insight into survival, hemodynamics, organ function, and adverse events [107].

Point-of-care testing (POCT), similar to ABG analysis, is widely used in both intensive care medicine and emergency departments, as the knowledge of particular blood parameters may require further therapeutic procedures in the treatment of life-threatening conditions. Therefore, it is considered a common adjunct to the treatment of in-hospital cardiac arrest [5,54]. Beyond differentiating respiratory disorders, further, potentially reversible causes of cardiac arrest may be detected and treated by means of ABG analysis; for example, metabolic disorders, such as acidosis and alkalosis, as well as electrolyte abnormalities, such as hypo or hyperkalemia. The measurement results may trigger interventions such as the optimization of artificial respiration, the correction of acidosis (ventilatory or sodium bicarbonate), antidote, vasoactive, or fluid therapy, or may accelerate admission to the hospital for resuscitative hemodialysis [108,109].

Due to the size, energy demand, and characteristics of the analytical equipment, even if measured at the “point of care”, most POCT applications had been restricted to health care facilities. With the advent of portable devices, blood gas analyzers have become available in the field [110,111]. Meanwhile, technological advances have enabled a rapid and reliable application in the prehospital environment [108].

The parameters obtained may support the responsible team in diagnosis and treatment decision-making [108,109]. While survival data from RCTs are still missing, it seems obvious that patients might profit from the earliest possible recognition and treatment of reversible causes during OHCA [112].

In addition to chest trauma as a main cause, pulmonary diseases, such as acute exacerbation of chronic obstructive pulmonary disease with consecutive pneumothorax, may be accompanied by progressive ventilatory and/or cardiocirculatory distress [113]. There is a risk of developing a life-threatening tension pneumothorax, which can be fatal if left untreated. Needle decompression and thoracostomy with or without drainage insertion are, therefore, life-saving interventions. The relief of tension pneumothorax by means of pleural puncture or minithoracostomy is an established invasive procedure. It is one of the basic techniques in the care of critically ill patients and every doctor working in emergency medicine must be able to perform it [92,114].

In highly dynamic situations with foudroyant shock, needle decompression is useful, as it is quick and easy to perform. Classically, it is performed in the Monaldi position in the second or third intercostal space of the midclavicular line. The indwelling venous cannulae often used for needle decompression are too short to reach the pleural space for a relevant proportion of patients [115,116].

A tension pneumothorax can usually only be relieved for a short time with the puncture, so it seems sensible to always perform a minithoracostomy afterward [119]. The minithoracostomy is performed in the Bülau position. The life-saving intervention is the opening of the pleural space, not the insertion of a drain. Whether a chest drain should be inserted at the scene or in the hospital remains the subject of ongoing debate. Recent retrospective data suggest that there could be an increased risk of recurrent tension physiology if thoracostomy is not followed by the placement of a drain [120].

While chronic pericardial effusion, for example, due to infectious, inflammatory, or malignant disease, usually develops slowly, rapid accumulation in the event of a disease flare-up can lead to subacute cardiocirculatory decompensation. In the event of aortic dissection, after thoracic trauma or iatrogenic perforation (for example, PCI, aortic, or cardiac surgery), the development is dramatic. Even small amounts of blood can lead to a significant increase in intrapericardial pressure within a few minutes and clinically manifest pericardial tamponade [121].

Clinical diagnosis of pericardial tamponade (Beck’s Triad: hypotension with a narrowed pulse pressure, jugular venous distention, and muffled heart sounds) is difficult and unreliable, especially in a peri-arrest situation. As acute tamponade is not associated with a large effusion volume, a rather small effusion of 50 mL can cause cardiac tamponade in a hypovolemic state and lead to cardiac arrest. This reversible cause has to be treated immediately in order to restore perfusion. In this case, prehospital emergency ultrasonography is essential [121,122]. Furthermore, the integration of ultrasound reduces the time until relief of the pericardial tamponade [123].

In principle, two phenotypes of tamponade can be distinguished sonographically. On the one hand, a liquid tamponade is easily accessible for puncture; on the other hand, extensive clot formation can occur in the case of a hemopericardium. In the latter case, relief by pericardiocentesis is not promising and relief must be achieved by thoracotomy, as described below [54,119,121].

It must be mentioned restrictively that, to date, there is no systematic data available regarding the cause of cardiac tamponade in non-traumatic cardiac arrest. If the cardiac arrest was caused by aortic dissection or ventricular rupture, simply relieving tamponade could not solve the problem, as the underlying pathology cannot be treated with the options available in an out-of-hospital setting.

The resuscitative opening of the chest by means of a clamshell thoracotomy provides a quick overview and allows control of intrathoracic bleeding, proximal aortic compression, and access to the pericardium in cases of suspected or ultrasound-confirmed tamponade [92,124,125]. Therefore, it is indicated in traumatic cardiac arrest rather than sudden cardiac death. Nevertheless, this procedure is supposed to be discussed here as an advanced invasive resuscitation technique for the sake of completeness. As an invasive emergency technique, thoracotomy is firmly established in the current guidelines for cardiopulmonary resuscitation and polytrauma care, although the indication must be restrictive. According to the “4 E” rule, clamshell thoracotomy is only indicated if certain conditions concerning expertise, equipment, environment, and elapsed time are met [54].

Compared to left anterolateral thoracotomy, clamshell thoracotomy is more suitable for potentially reversible causes of trauma-induced cardiovascular arrest. It allows an excellent overview of the intrathoracic organs and thus a wide range of interventions [124].

11. Discussion of Concepts and Strategies

11.1. Decision-Making and Timing

11.2. Emergency Response and Continuing Care Structures

12. Conclusions