Cardiac arrest is one of the most critical emergencies inside an emergency room. Despite the progress on treatment tools, it is still one of the emergencies with the lowest survival rates after treatment. Therefore, ongoing research for alternative therapies look for improving patient output or identifying subjects that would not receive the benefits of the therapeutic approaches due to a slight or null probability of response. Ultrasound use among non-radiologist physicians has been steadily growing and it becomes more useful for either diagnosis or therapies.7 In Colombia, the use of ultrasound by non-radiologist physicians, and especially by emergency room medical staff, is scarce due to the limited resources available and the lack of training. Not all the high complexity hospitals have an ultrasound device in the emergency room, even if there is a growing evidence of the helpfulness on the bedside patient setting.8 In Colombia, we need to increase the body of evidence of benefits from ultrasound use in order to expand the adoption of this tool by well-trained staff. This work was carried out on a cohort of cardiac arrest patients to determine the prognosis of different arrest rhythms, especially on patients with pPEA, which can only be diagnosed by a bedside ultrasound device.
This work showed that sex and age at the cardiac arrest of the studied patients are similar to other studies,9 which renders this group comparable to other cohorts in published literature. Global survival at discharge of the studied cohort was 16.6 %, which is a high percentage when compared to other reports in literature.10 This high percentage could be attributed to the fact that most of the cardiac arrests were witnessed and they occurred in an inpatient setting. Nevertheless, among the studied patients, no differences were found for patient output according to place of cardiac arrest, if the cardiac arrest was witnessed or not, and the prior functional status, which could be related to the population size limitations. Regarding the factors associated to ROSC, we found that cardiac arrest time is directly related to ROSC: a six-minute (IR: 4-12) resuscitation has a higher probability of response than a 15-minute (IR: 10-21) resuscitation. This is in line with previous studies, where patient survival was related to cardiac arrest time.9 Therefore, it is advisable to reconsider extended cardiopulmonary resuscitations for patients, since this would represent a futile effort.
VF/VT rhythm was the least common. This finding is in agreement with some reports11 and it is probably related to advances on acute heart disease prevention, which generally results in cardiac arrest with a VF/VT rhythm, while other pathologies generally result in cardiac arrest with other types of rhythms, especially non-shockable rhythms. Regarding the relationship between the cardiac arrest rhythm and prognosis, we found that PEA and asystole, in comparison with pPEA and VF/VT, showed significant differences for ROSC and survival at discharge. This is a relevant finding, since some reports show that shockable rhythms have better survival prognosis than non-shockable counterparts,12 maybe due to the fact that patients with this activity type have some degree of cellular perfusion, as opposite to patients without electrical activity. It is worth to mention that this study did not compare prognosis between VF/VT and pPEA, thus, we cannot conclude anything from this. However, it is clear that asystole patients have a worse prognosis than patients with some degree of electrical activity on the visoscope.
Concerning the patient group with PEA, this work is in line with previous studies3,13 that point to an ultrasound assessment for cardiac arrest patients with PEA, since presence of electrical activity (i.e., pPEA) could indicate higher probabilities of ROSC or even survival for the patient. Our study showed an important difference at survival level between patients with pPEA and PEA – 33.3 % vs. 0 %. These results are similar to other reports14,15 that show ROSC percentages of 50 % in patients with pPEA, while only 14.1 % in patients with PEA. This proves the important value of ultrasounds for cardiac arrest patients, not only to guide interventional procedures,16 but as a determinant in the prognosis to assess continuity or the eventual suspension of the cardiopulmonary resuscitation.
For patients with pPEA, we can describe the ultrasound activity, in other words, define if the patient with PEA has a predominant ventricular and valvular activity or only an isolated valvular activity. This study showed that the presence of cardiac and valvular activity resulted in significant differences for ROSC, but not for survival at discharge, when compared to isolated valvular activity. This probably suggests that the type of activity recorded during the ultrasound could be useful for the prognosis of the patient with cardiac arrest, so it is not possible to determine if a resuscitation is done without the use of the ultrasound at the bedside, this justifies the use of the Ultrasound as a tool in the assessment of the patient with cardiac arrest. However, further studies with better experimental designs are needed to test this hypothesis.