Impact of Introduction of Code Blue Response System in a Cardiorespiratory Center: Before–After Study

Abstract

Background:

In-hospital cardiac arrest demands immediate response to improve survival outcomes. The Code Blue Response System (CBRS) was designed to streamline emergency interventions by reducing response times. This study aimed to evaluate the impact of a CBRS on response times and outcomes before and after its implementation.

Materials and Methods:

A retrospective analysis was conducted using “Code Blue” feedback forms collected between April 2023 and March 2025. During this period, 212 patients who experienced code blue events were divided into pre-CBRS (n = 105) and post-CBRS (n = 107) groups, based on whether their code blue event occurred before or after the CBRS installation. Demographic data, response times, interventions (such as defibrillation and central venous access), and return of spontaneous circulation (ROSC) rates were analyzed.

Results:

Post-CBRS implementation, the mean response time significantly decreased from 2.65 to 1.71 min (P < 0.001), reflecting a 35.5% reduction. Defibrillation and central venous access rates also increased significantly (P < 0.001 and P = 0.03, respectively), demonstrating the positive impact of CBRS on patient outcomes. Although the ROSC rate improved from 42.3% to 53.3%, the difference did not reach statistical significance (P = 0.78). No significant differences were noted in patient demographics, event location, or time of day.

Conclusion:

The implementation of CBRS significantly improved code blue response times and enhanced critical interventions, contributing to better immediate patient outcomes. While the ROSC rate improvement was not statistically significant, the trend suggests a positive clinical impact. CBRS stands out as an essential strategy for improving emergency response efficiency and patient survival rates in hospitals.

INTRODUCTION

In-hospital cardiac arrest (IHCA) is a time-critical medical emergency associated with high morbidity and mortality rates. Globally, the annual incidence of IHCA ranges from 1.5 to 5 events per 1,000 hospital admissions, with survival to discharge varying widely between 15% and 25% depending on the institution’s resources and protocols.[1] Among the many factors influencing survival, the time taken to initiate resuscitative efforts is paramount. In this context, the Code Blue Response System (CBRS) has emerged as a structured and vital tool for reducing response times and enhancing resuscitation outcomes during cardiac emergencies.[2] Prompt response is crucial to reduce mortality and morbidity, with early recognition and swift, accurate intervention playing a key role in patient survival.[3,4] Code blue is a rapid response system developed for emergency resuscitation and stabilization of any IHCA within a hospital.[3]

As a result, the importance of the CBRS in hospitals continues to grow. Code blue is a critical alert system activated during cardiac or respiratory arrest, designed to facilitate rapid and effective intervention. It is the only universally recognized emergency code, using the same color worldwide for this specific situation, and it aims to establish a common language and streamline communication among healthcare providers. Given the complexity and size of hospitals and the diverse range of services offered, it is essential to train healthcare professionals, designate code blue teams, implement an efficient alert system, and ensure the system operates smoothly.[4,5] Code blue calls serve as a hospital-wide alert system that mobilizes a specialized team to provide immediate resuscitation efforts, increasing the chances of restoring spontaneous circulation (ROSC) and improving survival rates.[6] Code blue is the term used to denote an emergency medical condition in which the patient does not have a pulse and is struggling to breathe or has suffered cardiac arrest. The American Heart Association (AHA) (2016) defined cardiac arrest as the sudden loss of cardiac activity in a person who may or may not have any underlying or pre-existing cardiac conditions and can be terminal if corrective measures are not instituted immediately. Most victims of cardiopulmonary arrest tend to survive if the intervention is early, in terms of reaching the site early, cardiopulmonary resuscitation (CPR), defibrillation, and advanced care. The AHA recently reported that about 90% of people suffering a sudden cardiac arrest will die from the incident. CPR initiation or basic life support (BLS) could double or even triple overall survival and health outcomes.[4,5] The only way to survive a sudden cardiac arrest is when CPR is performed immediately after the arrest.

The installation of a well-organized CBRS is vital to minimize delays in intervention. By streamlining communication, assigning roles, and ensuring the availability of necessary equipment, CBRS enhances the ability of healthcare professionals to act swiftly.[7,8] Ours is a tertiary cardiorespiratory center. The primary aim of this study is to analyze how response times improve with the implementation of CBRS. The secondary objective is to compare the time to achieve ROSC, interventions, and outcome parameters before and after the installation of CBRS. Understanding these metrics is crucial in assessing the impact of CBRS on patient survival during code blue events, where saving lives truly depends on how fast and effectively the system can be activated.

MATERIALS AND METHODS

The study included all the “Code Blue” feedback forms filled up after completing a “Code Blue” by the rapid response team during the period from April 23 to March 25, and the response time noted before and after CBRS installation. The approval of the Institutional Ethics Committee was obtained. Since the code blue involves emergency medical interventions during a crisis, a waiver of consent was granted. The retrospective study was conducted in the tertiary center of Cardiorespiratory Sciences, and this study included patients of all ages who had a code blue declared in the hospital between April 2023 and April 2025 (24 months). The patients were divided into two groups, pre-CBRS and post-CBRS, according to before or after the installation of CBRS, respectively. This CBRS was installed on April 1, 2024, so the code blue call was placed for patients’ study group divided into two groups: pre-CBRS—patients who had code blue declared before the installation of the CBRS in the hospital between April 2023 and March 2024 and post-CBRS—patients who had code blue declared after installation of the CBRS in the hospital between April 2024 and March 2025. The code blue forms included demographics of patients (age, gender), response time, reason for code activation, interventions performed during the code, duration of code, and reasons for termination of the code outcome. Time of the day has been divided in view of its effect on response time, viz., office working time (8 am to 5 pm) and non-working hours. Non-working hours have been further divided into day and night. Non-working daytime includes morning from 6 am to 8 am and 5 pm to 8 pm, while night-time extends from 9 pm to early morning 6 am. Similarly, location has been divided to assess the response of code blue into various intensive care units (ICU), wards, and outpatient department (OPD) complexes. ICU included both medical, i.e. cardiac and respiratory and surgical ICU. OPD complex included cardiac, respiratory, flu clinic, and emergency OPD. Responders to code blue warning were classified as first responders if the team arrived at the scene and the patient was not being given CPR, while they were recorded as second responders if the closest hospital staff member or trained individual immediately started the BLS measures like CPR, and the team continued resuscitative efforts.

Statistical analysis

The paired data before and after the installation of CBRS were analyzed using appropriate statistical tests. The normality of the data was checked using the Shapiro–Wilk test. The continuous data was analyzed using the paired t-test for normally distributed data and the Wilcoxon signed rank test for non-normal data. The nominal data was analyzed using the McNemar test, while the analysis of variance/Friedman test was used for data comparison in more than two groups. Statistical analysis was performed using SPSS software (IBM SPSS Statistics version 24, Chicago, IL, USA). P value < 0.05 was considered statistically significant.

RESULTS AND OBSERVATIONS

A total of 221 code blue forms were obtained for the analysis of the code blue after and before the CBRS installation during the study period of April 23 to March 25. Among the 221 code blue, 4 pre-CBRS and 5 post-CBRS code blue forms were excluded due to false calls, so a total of 105 pre-CBRS and 107 post-CBRS code blue forms were included [Figure 1].

Figure 1.

Consort diagram. CBRS: Code Blue Response System, ROSC: Return of spontaneous circulation

The average age of patients was similar between the two groups (P = 0.26). A male predominance was observed, with a statistically significant increase in male cases in the post-CBRS period (P < 0.001). The location of code blue events, whether in the emergency room/OPD, ICU, or ward, showed no significant difference between the two groups (P = 0.84). Similarly, no significant variation was found based on the time of day the events occurred (P = 0.66). Regarding antecedent causes, cardiac events were the leading cause of code blues in both periods. Respiratory causes and unknown/other causes were comparatively less frequent. Other causes included sepsis with multiorgan failure, end-stage kidney disease, and patients presenting to the emergency room for the first time without a prior diagnosis or known cardiorespiratory ailment. Responder distribution was slightly different; the proportion of first responders was higher in the post-CBRS group (23.4% vs. 14.3%), though this difference was not statistically significant (P = 0.09).

A key finding was the significantly reduced time to respond following CBRS installation. The mean response time taken to reach the patient in pre-CBRS was 2.65 min, and in post-CBRS was 1.71 min, revealing that there was about a 35.5% reduction in response time, which was highly significant (P < 0.001). Additionally, there was a notable improvement in immediate clinical interventions post-CBRS, such as the higher use of defibrillation (P < 0.001) and increased use of central venous access (P = 0.03). Although the rhythm on arrival (asystole, arrhythmia, or normal sinus rhythm) did not differ significantly between the groups (P = 0.1), there was a visible increase in the proportion of arrhythmias identified post-CBRS. Outcome did improve in terms of achieving ROSC but did not reach statistical significance (P = 0.78). Nevertheless, this trend suggests a positive impact of faster response times on survival rates.

DISCUSSION

The CBRS plays a crucial role in hospital settings by ensuring a rapid and coordinated response to medical emergencies, particularly cardiac arrests and other life-threatening situations. It enhances patient outcomes by enabling healthcare teams to intervene promptly with appropriate life-saving measures. Through well-structured protocols, trained personnel, and efficient communication, the system minimizes delays in critical care delivery [Table 1].

Table 1.

Demographic and outcome parameters

Parameter	Total n=212	Pre CBRS n=105	Post CBRS n=107	T*/χ2/z#	P
Age	65.9 + 14.9	66.8 + 16.3	65 + 13.5	3.1*	0.26
Gender (male) n (%)	148 (69.8%)	70 (66.7%)	78 (72.9%)	16.4	<0.001
Location
Emergency room/OPD	52	25	27	0.04	0.84
ICUs	147	72	75
Ward	13	7	6
Time of day
Day	66	30	36	0.2	0.66
Non-working hours (day)	85	45	40
Night	61	30	31
Antecedent cause
Cardiac	125	59	66	0.6	0.43
Respiratory	70	37	33
Unknown/others	17	9	8
Responder
First	40	15	25	1.69#	0.09
Second	172	90	82
Time to respond (mins)	2.18 + 1.26	2.65 + 1.44	1.71 + 0.8	2.5*	<0.001
Rhythm on arrival
Asystole	134	74	60	2.7	0.1
Arrythmia	47	14	33
Normal sinus rhythm	31	17	14
Defibrillation, n (%)	41 (19.3%)	11 (10.5%)	30 (28%)	49.5	<0.001
Central venous access, n (%)	87 (41%)	35 (33.3%)	52 (48.6%)	4.4	0.03
Duration of CPR (mins)	34.5 + 15.1	35.2 + 14.3	33.9 + 15.8	0.78*	0.43
ROSC achieved n (%)	101 (47.9%)	44 (42.3%)	57 (53.3%)	0.08	0.78

OPD: Outpatient department, ICUs: Intensive care unit, CPR: Cardiopulmonary resuscitation, ROSC: Return of spontaneous circulation

This study emphasizes that early reach to patients, i.e., reduction in response time for code blue after the establishment of CBRS, has made emergency medical services’ reach more efficient in a shorter time, and this implementation also gave a better outcome for patients in terms of achieving ROSC. This improvement in response time is crucial, as studies consistently show that rapid intervention in cardiac arrest cases directly affects patient survival. Timely initiation of CPR and advanced cardiac life support has been associated with improved outcomes in patients experiencing cardiac or respiratory arrest.[9] This aligns with previous research emphasizing the critical nature of rapid responses in emergencies, where delays can lead to worse outcomes.[6,10] According to a study, early initiation of CPR within 1–2 min is associated with better ROSC and long-term survival.[11] Furthermore, the AHA emphasizes that the probability of successful defibrillation diminishes with each minute of delay.[12] The time to achieve ROSC improved. This reduction is vital, as quicker restoration of ROSC is linked to higher survival rates.[7] The ROSC rate also increased, underscoring the effectiveness of the CBRS in enhancing patient outcomes during code blue events. These findings align with previous research that demonstrates how organized hospital systems for emergency responses can significantly improve survival rates.[8]

The positive impact of CBRS on response efficiency is consistent with global experiences. A structured system significantly reduced mortality and cardiac arrests outside the ICU.[7] On the installation of CBRS in our hospital, a dedicated team assigned with roles prior worked efficiently and in a seamless manner to provide timely CPR. Similar to our findings, these studies suggest that organizational factors, such as pre-assigned responder roles, centralized alert systems, and standardized protocols, can mitigate delays during emergencies.

Post-CBRS implementation, our study also observed significant enhancements in clinical interventions, most notably the increased use of defibrillation and central venous access. Timely defibrillation is a key determinant of successful outcomes in cases of ventricular fibrillation or pulseless ventricular tachycardia, two rhythms frequently encountered during sudden cardiac arrest. Studies have repeatedly shown that early defibrillation increases survival chances.[13] The structured coordination facilitated by CBRS likely ensured quicker access to defibrillators and trained personnel capable of using them effectively. The importance of central venous access in code situations cannot be overstated, as it allows for the administration of critical medications such as epinephrine, which the AHA recommends delivering every 3–5 min during cardiac arrest.[14] Improved access rates in the post-CBRS cohort demonstrate the role of better coordination in facilitating advanced life support (ALS) measures.

Notably, rhythm analysis on arrival did not differ significantly between the groups, although there was a visible increase in identified arrhythmias post-CBRS (33 vs. 14 cases). This increase may reflect improved assessment protocols or the availability of better monitoring equipment and trained personnel post-implementation. Early and accurate rhythm identification is critical for determining appropriate interventions—whether CPR, defibrillation, or ALS and may explain some of the improved outcomes, albeit not reaching statistical significance. Although the ROSC rate improved post-CBRS, this did not reach statistical significance. This lack of statistical significance may be attributed to the sample size; larger multicenter studies may be required to confirm the trend observed. Nonetheless, the directionality of the improvement supports previous evidence that quicker and more organized responses lead to better patient outcomes.[15]

An important yet often overlooked component of the code blue response is team dynamics and communication. Effective leadership and closed-loop communication significantly enhance the performance of code teams.[16] CBRS fosters an environment of preparedness and role clarity, which minimizes delays caused by confusion or duplication of tasks. Multiple studies also support the idea that clearly defined team roles improve not only the efficiency of CPR but also reduce errors.[17]

The demographic data in our study, including patient age and gender distribution, did not significantly influence outcomes, although a higher percentage of males was observed in the post-CBRS group (72.9% vs. 66.7%, P < 0.001). Gender differences in cardiac arrest outcomes have been previously documented. Studies indicate that while male patients are more likely to receive bystander CPR, survival differences are not consistently significant after adjusting for confounders.[18] Another important observation is that the CBRS had a uniformly positive effect across all hospital locations, including ICUs, wards, and emergency departments. No significant differences were found in location-based outcomes, indicating that CBRS benefits extend hospital-wide. This supports the conclusion that system-wide implementation of rapid response systems can mitigate location-based disparities in cardiac arrest management.[19,20] The timing of events—whether during working hours or off-hours—did not show significant differences in our study. However, other studies have reported poorer outcomes during night shifts due to reduced staffing and fatigue.[21] The standardized and automated nature of CBRS could potentially neutralize these discrepancies by ensuring consistency in emergency response regardless of the time of day.

Beyond clinical benefits, CBRS may also offer advantages in terms of training, auditing, and quality assurance. Structured systems provide data points that are essential for performance analysis and feedback. For example, the Institute for Healthcare Improvement recommends continuous monitoring and review of code blue events to improve quality.[22] Our study, by documenting pre- and post-CBRS outcomes, contributes to this feedback loop, helping administrators identify performance gaps and areas for improvement. The implementation of CBRS not only reduces response times but also facilitates improved coordination among healthcare providers. By standardizing communication, streamlining team mobilization, and ensuring rapid access to necessary equipment, CBRS minimizes the chaos that can sometimes accompany emergencies. The result is a more focused, efficient response, where each team member knows their role, reducing unnecessary delays and optimizing patient care.[4]

Despite the promising results, certain limitations should be acknowledged. Our study was retrospective and limited to a single tertiary cardiorespiratory center, which may affect generalizability. ROSC did not improve significantly in our study, but this could be possible as ROSC depends upon various other factors. Moreover, we measured only short-term measures; long-term survival and neurological outcomes were not assessed, which could reflect on the quality of CPR. Future studies should include multicenter randomized trials and follow-up assessments to validate the enduring benefits of CBRS.

CONCLUSION

A clear significant improvement is seen in the response time for code blue initiation, after the implementation of the CBRS, leading to a positive outcome in achieving ROSC. The implementation of the CBRS has led to significant improvements in response times and in-hospital emergency response metrics, particularly defibrillation rates and central venous access. The survival outcomes for patients experiencing cardiac arrest did improve but failed to reach a statistically significant level. These findings are encouraging and suggest that hospitals should prioritize establishing effective rapid-response systems to optimize care for critically ill patients. Further studies with larger sample sizes and longer follow-up periods are needed to confirm the sustained benefits of CBRS on survival and neurological outcomes. The broader implications of CBRS—including enhanced teamwork, consistent care delivery, and systemic preparedness—reinforce its essential role in modern hospital emergency management. Optimizing response systems through structured programs like CBRS offers a promising avenue to improve patient outcomes and save lives.

Conflict of interest

There are no conflicts of interest.

Funding Statement

Nil.