Author: Marco Tubaro (Rome, Italy)
The general issue of this symposium was the last “link” of the chain of survival, namely post- resuscitation care.
Prof. Koster from Amsterdam (The Netherland) showed the changes between the older and newer ILCOR guidelines, particularly regarding compression: the ventilation ratio (which switched from 15:2 to 30:2) and the extended use of the automatic external defibrillator (AEDs). The importance of therapeutic hypothermia (TH) and of coronary revascularization with PCI were stressed, since in the ILCOR guidelines TH has a class I indication for patients with return of spontaneous circulation (ROSC) after an out-of-hospital cardiac arrest (OHCA) due to ventricular fibrillation (shockable rhythm) and a class IIa indication in case of other cardiac rhythms.
On top of TH, other supportive measures were alluded to, such as normoglycaemia, haemodynamic optimization, anticonvulsive therapy, as well as oxygen management. Moreover, in a paper by Dumas et al, the rate of occluded infarct-related artery was 87% in case of ST elevation on the ECG, but also 63% in case of chest pain without ST elevation, suggesting an important role for urgent coronary angiography and PCI if needed. However, in spite of the good data in the literature, the implementation of TH and coronary angiography ± PCI for ROSC patients after OHCA is still lagging behind in the cardiological community, because, in order to implement a therapeutic strategy, medical science should work together with educational efficiency and local organization. OHCA systems of care should be implemented, linking the EMS with hospitals with 24/7 PCI and ICU facilities, as well as with TH capability. TH can be given at the same time (with good results, as in Dr. Noc’s experience in Slovenia) or after successful PCI. Quality control and specific reimbursement have also a key role for implementing this OHCA system of care.
Dr. Boettiger from Koln (Germany) talked about TH. He started with the first proposal of TH in a guideline, dating back to 1961. Many dangerous pathophysiological pathways have long been known to cause damage to the brain before, during and after cardio-pulmonary resuscitation (CPR) and ROSC. Many of these pathways can be halted by TH alone, whose use is linked to one of the lowest numbers-needed-to-treat (NNT) in cardiology (NNT=6). In 2003, Nolan et al. wrote the first ILCOR statement about TH after ROSC, and its indications were extended to children in 2005 and to newborns in 2010. The earlier TH is started, the better the results, while the various ways to cool the patients do not have a different impact on outcome. A simple icecold infusion can obtain patient cooling of 3.2 °C/hour, and there are data in favour of reaching a body temperature of 32°C instead of 34°C, particularly in case of ventricular fibrillation as the cause of the cardiac arrest. Rewarming is suggested at the speed of 0.2-0.3 °C/hour. Post-TH fever (> 38.5 °C), particularly if lasting more than 24 hrs, has an ominous significance. It is important to keep in mind that an early prognostication is not advisable, as in almost 10% of the patients with good prognosis, the therapy is prematurely terminated: the prognostication should not be performed before 72 hrs.
Dr. Bro-Jeppesen from Copenhagen (Denmark) addressed the issue of PCI after ROSC. It was previously demonstrated (Sunde et al.) that survival rate and good neurological outcome doubles with PCI, because around 38% of all patients with ROSC have an unstable coronary lesion at coronary angiography. On ECG recording in patients with ROSC after cardiac arrest, ST segment elevation can be demonstrated in 30-50% of the cases, according to the different series, while ST elevation was absent in 50-70% of the cases. Bro-Jeppesen et al found 93% of significant coronary lesions in patients with ST elevation on the ECG, while Dumas et al showed that successful PCI was linked to an odds ratio of 2.06 for in-hospital survival. A recent meta-analysis by Kern et al in pts with ST elevation on the ECG showed 60% overall survival, with 86% good neurological outcome. Survival is obviously better in patients with single vs multivessel disease, and is better in case of multivessel PCI than after PCI of the culprit artery only. Regarding patients without ST elevation on the ECG, the ESC guidelines on NSTE-ACS do not specifically address the issue of ROSC after cardiac arrest. Dumas et al demonstrated that patients without PCI have lower 1-year and 5-year survival and that effective PCI is linked to better survival in patients both with and without ST elevation. In conclusion, coronary angiography ± PCI can be considered in patients without ST elevation, but at high risk of coronary artery disease, with a “deferred” invasive strategy, i.e. performed within the first 24 hrs.
Finally, Prof. Deakin from Winchester (United Kingdom) addressed the issue of coronary and cerebral blood flow during cardio-pulmonary resuscitation (CPR). Two basic mechanisms should be considered, namely the cardiac pump and the thoracic pump. The heart is directly compressed between the sternum and the spine, and this can increase cardiac output and blood pressure, but only in the presence of adequate ventricular filling. On the other hand, any increase in the intra-thoracic pressure (during external chest compression, but also with cough) causes an increase in blood pressure, due to the fact that the wall of the arteries is more resistant to compression and keeps the vessel open, which is not the case of the veins. It is possible that the cardiac pump mechanism could be more important in early PCI, while the thoracic pump mechanism could be more active during prolonged CPR, cough CPR and in case of simultaneous ventilation. In animal studies, the generation of a good coronary perfusion pressure has a key role in resuscitation. As far as cerebral blood flow is concerned, it is much higher with simultaneous than non-simultaneous compression-ventilation. The use of mechanical compression devices is capable of increasing both myocardial and cerebral blood flow in animals, and the use of adrenaline further improves this favourable result.
