Impact of Realistic Simulation Training on Nurses' Cardiopulmonary Resuscitation Performance (SIM-CPR Nurses)

Cardiopulmonary arrest (CPA) represents one of the most prevalent cardiovascular emergencies worldwide and is associated with high morbidity and mortality. In Brazil, approximately 14 million individuals have some form of cardiovascular disease (CVD), accounting for nearly 400,000 deaths annually, which corresponds to about 30% of all deaths recorded in the country.

According to the Brazilian Society of Cardiology, CVDs were responsible for more than 198,000 deaths in 2020 and constitute the primary underlying causes of CPA. Early recognition of CPA is therefore critical, as it is directly associated with improved outcomes and better patient prognosis.

CPA may present with four cardiac rhythms: asystole, pulseless electrical activity (PEA), ventricular fibrillation (VF), and pulseless ventricular tachycardia (pVT). Among these, only VF and pVT are shockable rhythms. In adult patients with sudden cardiac arrest due to VF or pVT, the heart exhibits disorganized electrical activity that is ineffective in maintaining perfusion to vital organs. In such cases, survival rates are significantly higher when immediate chest compressions and early defibrillation are performed.

Defibrillation is defined as the delivery of a controlled electrical shock aimed at terminating an abnormal cardiac rhythm, particularly life-threatening arrhythmias. During defibrillation, an electrical current induces simultaneous depolarization of myocardial cells. Although this intervention does not directly restore effective cardiac output, it creates the conditions necessary for the resumption of organized electrical activity. If myocardial viability is preserved, pacemaker cells may regain control of cardiac rhythm, resulting in the return of spontaneous circulation (ROSC).

The energy dose delivered during defibrillation depends on the type of defibrillator used. Biphasic defibrillators, currently the most widely used devices, typically deliver initial shocks ranging from 120 to 200 joules, with the possibility of escalation according to manufacturer recommendations. In contrast, monophasic defibrillators generally require a fixed dose of 360 joules. A monophasic waveform delivers current in a single direction, whereas a biphasic waveform alternates the direction of current flow, a phenomenon known as polarity reversal, which improves defibrillation efficiency.

Evidence consistently demonstrates that early defibrillation is a key determinant of survival in cardiac arrest. The probability of successful defibrillation decreases rapidly over time, with each minute of untreated cardiac arrest resulting in a 7-10% reduction in the likelihood of ROSC. When cardiopulmonary resuscitation (CPR) is initiated promptly, this decline becomes more gradual, averaging 3-4% per minute. Early CPR can double or even triple survival rates in cases of witnessed sudden cardiac arrest. Furthermore, VF tends to deteriorate into asystole within minutes, reinforcing that immediate defibrillation is the definitive treatment for shockable rhythms.

Large-scale studies have demonstrated a strong association between shorter time to defibrillation and improved survival to hospital discharge. In one study involving over 12,000 participants, 4,546 presented with VF. A reduced interval between rhythm recognition and defibrillation was significantly associated with increased survival rates. When defibrillation was performed immediately after rhythm identification, return of spontaneous circulation occurred in nearly all cases. However, after 60 seconds, success rates declined to approximately 80-90%. Survival was 74% among patients who received defibrillation within the first three minutes after collapse, compared to only 49% among those who received defibrillation after this period.

Although undergraduate curricula in healthcare fields, particularly medicine and nursing, include training in cardiac arrest management, this type of care remains a significant challenge for many professionals. This highlights the need for more effective educational strategies aimed at improving knowledge retention, technical skills, and clinical performance in emergency situations.