Cardiopulmonary arrest (CPA) is a serious medical emergency characterized by the abrupt cessation of cardiac and respiratory functions, leading to imminent death if not treated promptly and effectively.^1,2 Its diagnosis is based on the assessment of responsiveness, respiration, and pulse, and its rhythms are classified as asystole, ventricular fibrillation, pulseless ventricular tachycardia, and pulseless electrical activity.³

Adequate response to CPA begins with early recognition and immediate activation of emergency medical services.⁴ Cardiopulmonary resuscitation (CPR) is the essential intervention to restore blood circulation and oxygenation of vital organs.⁵ Current guidelines recommend high-quality chest compressions, with a rhythm of 100 to 120 compressions per minute, associated with ventilation with a compression-to-ventilation ratio of 30:2, in the absence of an advanced airway.⁶

Recently, a remarkable phenomenon has been observed during CPR, called Cardiopulmonary Resuscitation-Induced Consciousness (CPRIC). This phenomenon involves the manifestation of signs of brain activity in patients during a CPA, even though spontaneous blood circulation does not return.^5,7,8 CPRIC includes behaviors such as eye opening, agonal breathing, increased jaw tone, responses to painful stimuli, intentional arm movements, and verbal and nonverbal communication with the resuscitation team.⁵

CPRIC is considered rare, occurring in less than 1% of in-hospital CPA cases.³ Although the physiological mechanisms are not fully understood, it is believed that rapid identification and quality of compressions during CPR are related to its occurrence. Effective compressions maintain a minimum mean arterial pressure and approximately 30% of the normal cardiac output, in turn reducing ischemic damage and neuronal death.^8,9 With the increasing efficiency of prehospital systems, the incidence of CPRIC has increased, which can negatively impact the quality of CPR and patient prognosis by potentially inducing interruptions in the process.^10,11

The occurrence of CPRIC significantly impacts the effectiveness of resuscitation maneuvers and can compromise the patient's outcome. The need to interrupt high-quality chest compressions to assess and document signs of induced consciousness can reduce cerebral blood flow and the oxygenation of vital organs, impairing the possible return of spontaneous circulation (ROSC) and increasing the risk of irreversible brain injury. Furthermore, decision-making about whether or not to continue CPR in cases of CPRIC is complex and can generate ethical and legal dilemmas for the care team.^12,13

Given the growing relevance of the phenomenon and the need for a better understanding of its occurrence and clinical implications, the present study aims to investigate the occurrence of CPRIC, in addition to verifying the knowledge and experience of health professionals and firefighters regarding this phenomenon.

Central Illustration contain a summary of the main data of the article.

This is a cross-sectional observational study using data obtained through the application of a self-administered questionnaire, intended for professionals who regularly participate in CPR procedures. The sample consisted of physicians, nurses, nursing technicians, and firefighters. Participants were selected through electronic dissemination of the questionnaire, which was distributed via social networks and professional contacts, reaching professionals from different regions of Brazil. However, the selection did not consider regional particularities or the proportional distribution of professionals by location, thus reflecting a comprehensive but non-stratified sample. The option for a non-probabilistic convenience sample was due to the difficulty of obtaining a complete and updated list of all professionals working in the area of CPR throughout the country, in addition to the intention of obtaining a significant response in a short period of time. Data collection was performed through a questionnaire developed by the authors, based on the phenomena of CPRIC, as described in the Australian study.³ The questionnaire covered the following aspects: the professional's profile and academic background, the professional's experience in CPA situations, knowledge about CPRIC, and the ability to recognize and identify signs associated with CPRIC.

The questionnaire, containing 19 questions, was made available online through the Google Forms platform from January to March 2024. Participants were invited to answer the questionnaire after reading and accepting the Free and Informed Consent Form (FICF), which guaranteed the confidentiality of the information and respect for the ethical principles of the research.

The present study included the participation of 507 professionals from different regions of Brazil, including physicians, nurses, nursing technicians and firefighters, working in the intra-hospital (IH) context and/or in pre-hospital care (PHC), with an average age of 41 years (Standard deviation, SD = 8.4) and predominantly male (58.2%). Among the participants, 57.2% were familiar with CPRIC, and 39.4% stated that they had witnessed at least one episode. The demographic and professional characteristics of the sample, as well as the inferential analysis of the data, are presented in Table 1, regarding knowledge of CPRIC, and in Table Y in relation to having witnessed CPRIC. Nurses and physicians made up the majority of professionals who are familiar with and have witnessed CPRIC episodes. Professionals with more than twenty years of experience and those who have witnessed more than twenty CPAs in the last year are more likely to be familiar with CPRIC. Most of these professionals worked in advanced life support units and had a specialization in the area.

This study investigated the knowledge, experience, and immediate conduct adopted by health professionals and firefighters when faced with CPRIC. Considering a sample of 507 professionals, the rate of CPRIC presence was 0.22%, which is in line with the rates reported in the study by Olaussen et al.,¹⁰ which ranged from 0.23% to 0.9%. The results indicated that the performance and number of CPAs witnessed were significantly associated with knowledge and having witnessed CPRIC. The number of CPAs witnessed in the last year is the most relevant factor for knowledge of CPRIC, while the performance in Emergency Care is the most relevant for witnessing CPRIC. These findings highlight the relevance of CPRIC in the clinical context and the need for greater understanding and preparation of professionals to deal with these cases.

Behaviors observed during CPR can raise several questions about awareness during CPR. In this study, the most observed behaviors included eye opening, attempts to interfere with resuscitation maneuvers, and psychomotor agitation, indicating some form of consciousness or brain activity. Additionally, moaning was another reported manifestation, suggesting possible vocal expression during CPR. Previous studies, such as West et al.,¹⁵ explored cognitive activity during CPR, showing the perception of lucidity, visual and auditory awareness during CPR, in addition to reports of near-death experiences.¹⁶ In this sense, the variety of behaviors reflects the wide range of individual experiences during CPR, highlighting the need for a deeper understanding and adaptive protocols.

In this study, the most common cardiac rhythms found during CPRIC were ventricular fibrillation (24.5%) and pulseless electrical activity (18.5%). In addition to these, the scientific literature also mentions pulseless ventricular tachycardia as a rhythm associated with CPRIC. A study by West et al.¹⁵ suggests that the presence of CPRIC may be more common in cases of CPA with shockable rhythms, highlighting the importance of recognizing and treating these rhythms quickly in order to increase the chances of successful resuscitation and improve the prognosis of patients.

The procedures adopted for CPRIC varied among professionals, reflecting the lack of specific protocols on the subject. In the present study, the most common actions were checking the pulse, temporarily interrupting massages, and immediately continuing CPR. By contrast, the literature suggests other approaches, such as administering sedatives to alleviate possible discomfort in the conscious patient during CPR.¹⁷ The lack of a standard among the procedures adopted highlights the need for standardized guidelines for the management of CPRIC. Notably, 79.3% of the professionals surveyed believe that including CPRIC in current CPR guidelines is crucial.

As observed in the results, among the patients who presented signs of CPRIC, 64.0% had a ROSC, suggesting a possible association between the presence of CPRIC and favorable cerebral perfusion. However, the long-term implications of CPRIC for patients and rescuers are still uncertain. Studies, such as that of Dąbrowski et al.,¹⁷ indicate that patients may develop cognitive sequelae, including post-traumatic stress disorder, after resuscitation. This raises concerns about the appropriate management of these situations due to the psychological and emotional impact of consciously experiencing CPR, both for the patient and for rescuers.

In this study, it was found that professionals are reluctant to use sedatives during CPA. The benefits of sedation in conscious patients during CPR are uncertain, and it is inappropriate to justify its use solely on the basis of the need for pain relief, considering that many CPA survivors report pleasant near-death experiences.¹⁸ Factors against sedation include the difficulty in neurological assessment and the risk of circulatory depression.⁹ However, since medications usually have a minimal effect on cardiac arrest outcomes, a small, controlled dose of sedation is unlikely to influence survival.^19,20 Studies have highlighted the importance of sedation and analgesia during CPR, emphasizing that medication should be carefully selected to support myocardial and cerebral blood flow. In addition, medications that are fast-acting, easy to administer, and reasonably priced should be chosen, despite the challenges inherent in this choice.^17,21

One of the main gaps identified in this study is the lack of specific knowledge and training on CPRIC. Only 57.2% of the participants demonstrated prior knowledge on the topic, while 42.8% were unaware of the phenomenon. The lack of data in the literature on prior knowledge of CPRIC reinforces the need to include this topic in CPR guidelines of several medical societies, such as the American Heart Association, the European Society of Cardiology, and the Brazilian Society of Cardiology. Including CPRIC in these guidelines would contribute to greater awareness among professionals about this condition, promoting a more uniform and effective approach.

In addition, the lack of standardized protocols and the scarcity of information on the topic within current CPR guidelines highlight the need for action by health authorities. To mitigate this problem, it is suggested that continuing education programs be implemented that cover the topic of CPRIC, focusing on realistic simulations, case studies and group discussions. The creation of online platforms and specific teaching materials can also contribute to the dissemination of knowledge about CPRIC.

It is important to emphasize that this study has limitations that may influence the generalization of the results. Data collection carried out through an online questionnaire may have generated selection bias, mainly attracting professionals with greater interest in the topic of CPR and CPRIC. In addition, the concentration of the sample in the Southeast region (80.3%), to the detriment of the other regions (South, 8.9%; North and Northeast, 5.9%; and Midwest 4.9%) limits the national representativeness of the findings. The absence of a stratified sample by region compromises the ability to generalize the results to the entire Brazilian territory, since practices and perceptions may vary significantly between different regions. Finally, the self-reported nature of the collected data may be subject to memory and interpretation biases, affecting the accuracy of the information provided in this study.

This pioneering study in the Brazilian context investigated the knowledge and practice of health professionals regarding CPRIC, revealing a limited understanding and significant variability in the adopted procedures, especially in PHC. The identification of these gaps highlights the urgent need to update CPR guidelines, including specific guidance on the management of CPRIC.

The results obtained in this study, although subject to methodological limitations, provide important support for future research and for the implementation of more effective educational strategies. A deeper understanding of the pathophysiology of CPRIC, the assessment of the impact of the use of sedation and analgesia, and the investigation of the long-term consequences for patients are issues to be addressed in future research.

In summary, this study demonstrates the clinical relevance of CPRIC and the need for a more uniform and evidence-based approach to its management. The implementation of specific clinical protocols, associated with continuing education programs, can significantly contribute to improving the quality of care for patients experiencing CPRIC and to optimizing the results of CPR.