The rapid response system (RRS) which may include a medical emergency team (MET), has been introduced into hospitals to decrease morbidity and mortality through the early detection of patients at risk of further deterioration [1,2]. These RRS provide additional information and assistance to the ward and intensive care unit, thus aiding diagnosis and treatment decisions for the patient. Following the introduction of the RRS, patient mortality rates have significantly decreased [3]. The need for RRS’s within hospitals is clear. This system improves the safety of patients in hospital, whose condition has deteriorated [4]. If an emergency occurs, patients are treated by the MET. In surgical wards, there are not always enough medical staff present on the ward. Surgical residents take part in the operation room after medical rounds and often only 1 doctor may be present on the ward. In addition, in the absence of senior staff, such as in the event of an emergency resulting from peri-operative complications, a junior resident may determine the diagnosis and treatment direction.

In this study, the reasons for activating the RRS were analyzed in relation to the patients’ medical conditions whilst on the surgical ward), and the time at which the RRS was initiated was recorded. In particular, we investigated whether there was a difference in the time of event occurrence in the surgical general ward depending on the number of medical staff, and the time required for patient intervention. Diurnal variation was investigated (by classifying daytime and nighttime) related to an increase / decrease of medical staff present on the surgical ward. The results of this study may be used to determine the distribution of medical resources within a hospital.

A retrospective observational study was performed to evaluate the effect of the MET of a RRS in general surgery wards. The study included patients admitted to the surgical wards of a 1,960-bed, university affiliated, tertiary referral hospital in Seoul, South Korea from May 2013 to July 2016. The surgical ward [8 wards of general surgery (50-60 beds per ward)] provided general care for approximately 320 to 400 patients per day. The Institutional Review Board approved the review and presentation of the information obtained from the patient records.

The number of times MET activation occurred in the surgical wards were recorded from 2013 to 2016. All patients fulfilled the criteria required for the MET activation, and had undergone surgery or needed surgery. Data was obtained from 465 MET events. The mean patient age was 65.5 years and 68% of patients were male. There were 67 MET activations in 2013, 143 in 2014, 142 in 2015, and 143 in 7 months in 2016. Among 465 total MET activations, there were 8 cases in which no additional intervention was performed. Reasons for no additional medical intervention included patient or care-giver’s refusal, wrong contact, or direct intervention in the hospital.

The average time from the moment the symptoms first appeared until the MET activation was 151 minutes. It took an average of 110 minutes to determine the additional medical intervention required, “do not resuscitate,” or ICU transfer. The number of ICU transfers increased annually from 34 patients in 2013, to 82 patients in 2016 (Table 2). MET activation increased markedly during the surgeons routine ward round between 08:00 and 10:00, with a peak call out of 25 MET activations, after which this decreased to 17 call outs at 12:00, and peaked at its highest between 17:00 to 18:00 (31 call outs) with the second ward round of the day (Figure 1). The time with the least number of call outs (5 call outs) was between 04:00 and 05:00 (Figure 1). The number of MET activations increased annually. There was no significant difference in the number of MET activations between daytime and night-time (Table 3).

In medical wards, patients may be old or have co-morbidities but there are enough physicians to cover ward rounds, care stations and wards, and for this reason the probability of a MET activation is low. However, in surgical wards, most patients do not have an underlying disease and are not typically old. Patients undergoing surgery are more likely suffer from perioperative complications in addition to common medical problems associated with their condition [11]. In addition, surgical residents also take part in the operation room after medical rounds. There are often no doctors or only 1 doctor on the ward. Due to the absence of a professor or senior residents in the event of an emergency (such as perioperative complication of the patient), a junior resident may be responsible for determining the diagnosis and treatment direction. Due to their lack of experience, a patient's treatment can be delayed and compromised. In an attempt to address these issues, the development of RRS in hospitals may help to improve patient care. The activation of MET as part of the RRS is known to help reduce mortality. Kwak et al [12] reported that hospital code rates decreased by 31.1%, and the mean inhospital mortality rate was reduced by 15.3% following the launch of RRS. Jones et al [13] also reported that MET activation increased long term survival of patients. Tobins et al [14] have shown that MET activation can reduce major metropolitan health network mobility. Tobins et al [14] have shown that Presence of a hospital MET system can reduce hospital mortaliy across a major metropolitan health network. However it appered to take more than 2 years after the implement.

Among the 465 MET activations, the most frequent activation period was from 17:00 to 18:00, with 31 activations, and the least number of activations in the period from 03:00 to 04:00. In order to identify vulnerable time periods on the surgical ward, the regular working hours of the residents at 08:00 to 17:59 (daytime) and 18:00 to 07:59 (nighttime) were examined. There were no significant differences in MET activation between day and night. However, MET activation increased when residents were on the ward round.

There were 50% of patients treated by a MET who were transferred to ICU, indicating the severity of conditions met by the METs. In this study, the average time from symptom onset to MET activation ranged from 86 to 143 minutes due to “trial-and-error delays” after the introduction of the RRS, where junior residents activated the MET. As a patient's condition deteriorates, the probability of needing care on an ICU increases [15]. In order to prevent “trial-and-error delays” the RRS needs to be automated with an urgent message system to team members of the EMT.

To understand the changes in a patient's condition and reasons for a medic’s request for a MET activation to carry out additional assessment and treatment is important. In this study, the MET call outs increased between 08:00 to 10:00, after the end of ward rounds, and then decreased after the surgeon moved to the operating theater. In the afternoon, when patients returned to the wards after their operations, MET call outs increased. The highest rate was observed around 18:00 when the afternoon ward round had finished. This indicated that there was an identifiable need for staff to remain on the ward when patients returned after their operation to quickly identify and respond to changes in a patient's condition.

The number of MET activations did not differ significantly between daytime and nighttime. During the daytime, post operation complications occurred after elective operations and this increased the number of activations of the MET. At nighttime, acutely deteriorating patients had a higher risk of in-hospital mortality [16]. Daytime emergencies can be resolved through consultation with other departments, even if the patient’s condition has met the MET activation criteria. However, at nighttime, the duty resident may manage the ward by themselves, and consultation with other departments is limited. Despite this, the activation of the MET did not show any differences between daytime and nighttime, however mortality and morbidity were not studied.

Medical staff should be able to stay in the ward as much as possible and the amount of time medical staff have been absent from the ward is decreasing. Recently, a system in the ward has been newly established with the introduction of a medic who can perform the role of the resident on the ward. In addition, in-patient satisfaction increased when a hospital-based general physician took charge of the work [9]. Although the system has not yet fully established and the physicians proficiency has not been developed [15], it can be expected their presence on the ward and care of patients will reduce the amount of time before activation of the MET. They can also help prepare for preliminary evaluations before further intervention directed by the MET.

This study has some limitations including non-classification of weekends and weekdays in this study. There may be differences in regular working hours without surgery between weekdays and weekends. During the 7 days of a week, 5 days are regular working days. However, on Saturdays and Sundays, doctors do not perform elective surgery so there is no decrease in the number of medical staff on the wards due to surgery on weekends but, the number of staff in attendance is lower. MET activation may occur more frequently towards the end of the week and on weekends. In addition, in-hospital mortality was not investigated in this study because the research objective was to determine whether activation of METs increased at vulnerable times of the day. The results of this study showed that MET activation increased during daytime when medical staff were absent. The RRS system and use of METs reduces mortality and morbidity [3,13,14]. However, recently it has been suggested that activation of METs is not associated with inhospital mortality [17,18]. Further studies are needed regarding in-hospital mortality on surgical wards, patient safety and the effects of METs.

In conclusion, the rate of MET activation in hospitals is increasing every year. Whether the RRS and specifically METs can reduce mortality is controversial and requires further study. The results in this study suggest that it may be beneficial to routinely introduce a physician to work on the surgical ward to improve patient safety.