In this episode, I’ll discuss an article about using thrombolysis during resuscitation for out-of-hospital cardiac arrest caused by pulmonary embolism.
Lead author: François Javaudin
Published in the journal CHEST December 2019
Pulmonary embolism (PE) is a common cause of cardiac arrest both in and out of the hospital. Survival rates are poor and addressing the pathophysiological issue of clot in the lung is essential if there is to be a chance of a positive outcome. Previous randomized trials have not found a benefit to the use of thrombolytic therapy in out-of-hospital cardiac arrest. The most recent American Heart Association and European Resuscitation Council guidelines recommend that thrombolysis be used when cardiac arrest is suspected as being caused by PE despite conflicting and inconsistent data. The authors of this study sought to review the French National out-of-hospital cardiac arrest (OHCA) Registry to examine whether thrombolytic use affected survival.
The study was a retrospective, observational, multi-center study that looked at all adults with OHCA in the registry over a 7 year period who had a diagnosis of PE confirmed on hospital admission. The primary endpoint was 30-day survival.
A total of 246 patients were included in the analysis out of over 14,000 possible OHCA patients admitted over the 7 year time period. Approximately one-quarter of these patients received thrombolysis during CPR. About three-quarters of patients received tenectaplase and one-quarter received alteplase. A single patient received streptokinase. Thirty-day survival was higher in the thrombolysis group than in the control group at 16% vs 6% and this was statistically significant with a p = 0.005. Good neurologic outcome occurred twice as frequently in the thrombolysis group however this did not achieve statistical significance. The duration of ICU stay was no different between groups.
The authors concluded:
In patients with OHCA with confirmed PE and admitted with recuperation of spontaneous circulation in the hospital, there was significantly higher 30-day survival in those who received thrombolysis during cardiopulmonary resuscitation compared with patients who did not receive thrombolysis.
Some critical points must be noted before deciding whether the results of this study can be applied to practice.
First, the study population was entirely in France and served by mobile ICUs. This type of emergency medical system is considerably different than that in the US or other countries. A mobile ICU consists of a driver, a nurse, and a senior emergency physician at a minimum.
Second, data completeness in the registry meant that 13 patients were excluded from the analysis due to unknown time of return of spontaneous circulation. Data on the dose of thrombolytic used was missing in more than half of the patients.
Third, determining whether the cause of cardiac arrest is PE is challenging. The factors associated with PE-related OHCA were previous history of thromboembolism and initial arrest rhythm that was nonshockable. In this population with these two factors, specificity was 98% and sensitivity 24%. The number of patients who received thrombolytics in the study was 20 times the number who received thrombolytics and later had a confirmed PE. Many of these patients who received thrombolytics had an MI but there is no way to tell by looking at the registry how many patients were potentially exposed to thrombolytics who did not have a confirmed PE.
Because this study did not find an improvement in neurologic outcome, I would be hesitant to try to implement out of hospital thrombolytics in an EMS system that is very different from the one in France until better data is available.
Members of my Hospital Pharmacy Academy have access to practical training on how to care of patients with high-risk PE from a pharmacist’s point of view, as well as how to handle intracranial hemorrhage after alteplase. Members also get access to the entire training library covering critical care, emergency medicine, infectious disease, and general hospital pharmacy, plus many more resources to help you in your practice. Get all the details and join today at pharmacyjoe.com/academy.
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