Peri-operative cardiac arrest is a dramatic and serious complication but was previously described as the stepchild of emergency medicine. 1 However, current resuscitation guidelines now include a section on peri-operative cardiac arrest, 2 underlining the relevance of this special situation.
In recent literature, it is well documented that children have a higher incidence of peri-operative cardiac arrest than adults, 3,4 and in a study from our institution, five out 12 anaesthesia-related cardiac arrests in an unselected (adult and paediatric) cohort of 169 500 anaesthetics occurred in paediatric patients. 5 Studies of peri-operative paediatric cardiac arrest 6–15 have been conducted predominantly at specific paediatric hospitals. 7,10,13–15
A recent pan-European multicentre study revealed a high rate of severe critical events in a large peri-operative paediatric cohort, with an impact of the anaesthesiologist's experience on the rate of complications, especially in critically ill and young children. Furthermore, this important study found a variable incidence across Europe, 16 and the risk of cardiovascular critical events in patients of ASA physical statuses 3 to 5 was higher for occasional or frequent providers compared with dedicated providers of paediatric anaesthesia. Another ongoing European research project (NECTARINE) focuses on anaesthesia practice and outcomes in neonates and young infants, underlining that this group is at high risk of peri-operative complications. 17 Access to more experienced healthcare teams might reduce the adverse event rate and improve outcomes. 16,18
In this report, we analysed the incidences and causes of peri-operative paediatric cardiac arrest, especially those attributable to anaesthesia, in a German tertiary care university hospital before and after implementing a special paediatric anaesthesia team and training programme in 2014.
Ethics approval was waived by the local Ethics Committee of the University Hospital of Cologne due to the retrospective nature of the study (Ethics Committee No. 17-396).
A machine-readable anaesthesia record system was implemented in our department in 2008 to allow the electronic storage of data. In addition, it is mandatory in our institution to report any peri-operative complication on a specific critical incident report form. This report is written by the anaesthesia team involved in the case and stored together with the anaesthesia record in a dedicated database. We screened all critical incident reports and reports of peri-operative cardiac arrest within 24 h postoperatively in patients younger than 18 years of age collected between February 2008 and December 2016. A cardiac arrest was defined as the cessation of cardiac mechanical activity as confirmed by the absence of signs of circulation requiring cardiopulmonary resuscitation. 19,20 Critical incidents from the ICU were excluded from this analysis to focus on anaesthesia-associated problems. Each patient's anaesthesia protocol, medical records and the critical incident report on each cardiac arrest were analysed independently by three investigators (AH, UT, SAP).
Our department provides paediatric anaesthesia for many different surgical specialities: classical paediatric surgery, neurosurgery, cardiac surgery, orthopaedics, otorhinolaryngology, ophthalmic surgery, urology, maxillofacial surgery and dental medicine, cardiac catheterisation, radiological imaging (e.g. MRI) and other diagnostic procedures. Before 2014, only a small group (5 to 6) of anaesthetists dealt predominantly (50 to 80%) with paediatric anaesthesia, mainly in diagnostic procedures and cardiac surgery as well as cardiac catheterisation, and only occasionally in other departments. Overall, they were able to cover only about 25% of the paediatric cases in the hospital. As a result, the majority of paediatric cases were managed by the rest of the team with varying staff and fluctuating paediatric anaesthetic experience.
In 2014, a specialised paediatric anaesthesia team and training programme were implemented at our institution, and nowadays about 80 to 90% of all paediatric cases can be covered by the specialised team. In addition to daily practice in the field of ‘classical’ paediatric anaesthesia, the training programme included practice in paediatric cardiac intensive care, and in anaesthesia and sedation for cardiac catheterisation and other interventional or diagnostic procedures.
The training team consists of two anaesthetists (consultants) and a specially trained nurse. One of the anaesthetists is from the ‘experienced group’ with 2 to more than 15 years of practice in paediatric anaesthesia and paediatric intensive care and one from the ‘training group’ (0.5 to 2 years of specialised paediatric anaesthesia training). Furthermore, a monthly teaching session for paediatric anaesthesia was introduced and supervision of sedation for diagnostic procedures was improved. The composition and training of our specialised team was built on the basis of the ‘European guidelines for training in paediatric anaesthesia’, which were published in 2007 by the Federation of European Associations of Paediatric Anaesthesia, the predecessor of the European Society of Paediatric Anaesthesia, and which are still an excellent basis for training. 21
As part of these measures, the specialised anaesthesia team increased to nearly 20 members and, since then, well trained paediatric anaesthetists are available even in remote locations for both routine paediatric cases and children at high risk (e.g. congenital heart disease). For very young children and in children at high risk, there are always two experienced anaesthetists to take care of the patient.
The introduction of the specialised paediatric anaesthesia team was combined with further measures:
- Before 2014, standard operating procedures were present only for paediatric cardiac surgery. In 2014, a broad spectrum of most aspects of paediatric anaesthesia was added, including premedication, monitoring, vascular access, fluid management, regional anaesthesia, cardiovascular management of preterm infants, prevention of postoperative nausea and vomiting, pain therapy and a revised dosage list.
- A monthly teaching session for paediatric anaesthesia was introduced with separate monthly teaching for nurses as well.
- Yearly European Paediatric Life Support courses according to the Guideline of the European Resuscitation Council were started in 2012 with four to five participants from our own department; by 2014, about 10 anaesthetists had completed this training in paediatric resuscitation.
- Moreover, an emergency team (two anaesthetists and a specially trained nurse) is available 24/7 to improve anaesthetic care in paediatric emergencies.
- During day time, the specialised paediatric team can also be made available for anaesthesia in cases in which problems occur or are foreseen and where paediatric anaesthetists are not regularly present.
In summary, in 2014, a hands-on supervised training in all fields of paediatric anaesthesia, double staffing for critical paediatric cases (<2 years, ASA physical status >2 and every time the responsible team requested support from a special paediatric anaesthetist), and a 24/7 emergency team was implemented at our institution.
Anaesthesia-attributable cardiac arrest
A classification modified from the Australian system of classification by State-Based Anaesthesia Mortality Committees was used to categorise cardiac arrest (Supplemental Digital Content 1, http://links.lww.com/EJA/A165). 22
- Anaesthesia-related cardiac arrest was defined as cardiac arrest that is caused directly by anaesthetic measures in the context of surgery or interventional procedures (category 1).
- Anaesthesia-contributory cardiac arrest was defined as cardiac arrest caused by both surgical-associated and anaesthesia-associated factors or where there is some doubt whether cardiac arrest was entirely attributable to the anaesthesia or other factors under the control of the anaesthetist (categories 2 and 3).
- Anaesthesia-attributable cardiac arrest was defined as cardiac arrest according to category 1 (anaesthesia-related cardiac arrest) or category 2 (anaesthesia-contributory cardiac arrest).
Adverse events leading to cardiac arrest
The primary adverse events leading to cardiac arrest were further graded similar to the categories used by Cheney et al. 23 : respiratory, cardiovascular, medication-related, equipment-related, regional anaesthesia-related, procedural, iatrogenic or other not further classified incidents.
Finally, cardiac arrests were classified by the reviewers as definitely preventable, possibly preventable or not preventable.
Rates of cardiac arrest are shown as incidences per 10 000 anaesthetics and 95% confidence intervals (95% CI). Logistic regression analysis with a step function (before and after 1 Jan 2014) was used to identify risk factors which were independently associated with the endpoint (cardiac arrest). In addition to year, ASA physical status, age and emergency indication were included as categorical covariates, with backward stepwise selection. A P less than 0.05 level of significance was chosen. Results of logistic regression analysis are reported as odds ratios (ORs) with 95% CI. Overall predictive accuracy was assessed using the area under the receiver operating curve. Risk factor analysis was carried out by comparing the incidence of cardiac arrest between the groups. Categorical variables were calculated as numbers and percentage. Data were documented with Microsoft Excel 2013 (Microsoft, Redmond, Washington, USA) and analysed with SAS software version 9.3 (SAS Institute Inc., Cary, North Carolina, USA).
During the study period, 36 243 paediatric anaesthetics (0 to 18 years of age) were performed. The number and proportion of anaesthetics in children younger than 3 years and the rate of patients classified as ASA physical statuses 3 to 5 increased steadily during the observation period (Table 1). Likewise, the proportions of children less than 1 year and less than 1 year + ASA physical statuses 3 to 5 were greater in the population in the years 2014 to 2016 compared with the years 2008 to 2013.
Between February 2008 and December 2016, we identified 25 reports of peri-operative paediatric cardiac arrest. This is in an overall incidence of 6.9 peri-operative cardiac arrests (95% CI 4.7 to 10.2) per 10 000 anaesthetics. The overall incidence (n=12) of anaesthesia-attributable cardiac arrest was 3.3/10 000 (95% CI 1.9 to 5.8) anaesthetics between 2008 and 2016 (Table 1). During the study period, the annual incidence of cardiac arrest varied from 2.5 to 12.2 per 10 000 anaesthetics, and from 0.0 to 9.1 per 10 000 anaesthetics for anaesthesia-attributable cardiac arrest.
The incidence of overall peri-operative paediatric cardiac arrest was 8.1/10 000 (95% CI 5.2 to 12.7) in the period 2008 to 2013 and decreased to 4.6/10 000 (95% CI 2.1 to 10.2) in the period 2014 to 2016 (Fig. 1, Table 1). Likewise, the incidence of anaesthesia-attributable cardiac arrest was lower after 2013 (1.6/10 000, 95% CI 0.3 to 5.7 vs. 4.3/10 000, 95% CI 2.3 to 7.9).
Logistic regression analysis with risk factors age, ASA physical status and emergency, revealed younger ages and ASA physical status 3 to 5 as significant risk factors for peri-operative cardiac arrest in general and anaesthesia-attributable cardiac arrest. As the inclusion of a nonsignificant factor increases the influence of random scattering on the results of the regression, the nonsignificant factor ‘emergency’ was removed from the further statistical analysis. Table 2 shows the ORs for cardiac arrest in different subgroups. Infants and children at younger ages had a statistically significantly higher risk of peri-operative cardiac arrest in general, and in particular for anaesthesia-attributable cardiac arrest. The OR for ASA physical status 3 to 5 compared with ASA physical statuses 1 or 2 was greater for any peri-operative cardiac arrest than for anaesthesia-attributable cardiac arrest. Children anaesthetised between 2014 and 2016 were at lower risk (OR 0.306, 95% CI 0.067 to 1.397, P = 0.1263) for anaesthesia-attributable cardiac arrest. However, this effect was not statistically significant.
Eight cardiac arrests were related to anaesthesia alone, anaesthesia was contributory in four cardiac arrests and 13 cardiac arrests were classified as unrelated to anaesthesia. Of 25 patients with cardiac arrest, 23 were classified as ASA physical status 3 to 5. Sixty per cent (15/25) of cardiac arrests occurred in children aged younger than 1 year. Cardiac arrest was assessed as definitely preventable in two cases (Table 3). In both cases, an accidental medication error led to cardiac arrest, and both preventable incidents occurred during the first period (2008 to 2013).
In 11 of 12 (91.7%) anaesthesia-attributable cardiac arrests, patients were aged 3 years or younger. Fifty per cent (n=6) of children with anaesthesia-attributable cardiac arrest were aged younger than 1 year. Seven patients did not survive peri-operative cardiac arrest to hospital discharge. In three cases, severe trauma led to cardiac arrest, and in three other cases, fatal cardiac arrest occurred during heart catheterisation.
Fourteen (56%) cardiac arrests occurred during cardiac surgery or heart catheterisation. Figure 2 shows the number of peri-operative paediatric cardiac arrests in children undergoing cardiac procedures (cardiac surgery or cardiac catheterisation). The proportion of anaesthesia-attributable cardiac arrest was higher in the noncardiac setting compared with cardiac procedures. In the period 2014 to 2016, no cardiac arrest occurred in the noncardiac setting.
In six of 12 anaesthesia-attributable cardiac arrests, respiratory and airway problems were the primary adverse events leading to cardiac arrest, whereas in all cardiac arrests, cardiovascular problems were the leading adverse events (15/25) (Fig. 3).
In this retrospective cohort study, the incidence of both overall peri-operative cardiac arrest and anaesthesia-attributable cardiac arrest was on average lower after implementation of a specialised paediatric anaesthesia team and training programme despite an increase in the proportion of children aged less than 1 year and an increase in the proportion of patients aged younger than 1 year and classified as ASA physical status 3 to 5. Although children anaesthetised after 2013 had nearly a 70% lower probability of anaesthesia-attributable cardiac arrest, this effect was not statistically significant. The low frequencies of cardiac arrest during the study period may explain the lack of statistical significance. A longer second observation period would possibly have increased the chance to find a significant reduction of cardiac arrest. Moreover, the number of anaesthesia-attributable cardiac arrests could not be reduced to zero by our measures. However, the seemingly high number of anaesthesia-attributable cardiac arrests in 2015 should be interpreted with caution as the total number of anaesthetics in children aged 3 years and younger was about 20% higher in the period 2014 to 2016.
Young age was the most strongly contributing risk factor to anaesthesia-attributable cardiac arrest, whereas in overall paediatric cardiac arrest, ASA physical status 3 to 5 played a more important role. However, CIs for ORs were wide. Age and ASA physical status have previously been described as potential risk factors for peri-operative paediatric cardiac arrest. 7–11,13,15 Significantly, emergency status appeared not to be a significant risk factor for cardiac arrest in our study population, and we could not demonstrate a difference in incidences of cardiac arrest in emergencies before and after the intervention. Probably, the numbers of such cases were too small to analyse either the role of emergency status on the risk of cardiac arrest or the effect of implementation of the specialised team on the risk for emergency cases alone. However, most studies report that children undergoing emergency procedures are at a higher risk of peri-operative cardiac arrest, 6,7,9,11,24,25 but in a recent study, there was also no difference in peri-operative paediatric cardiac arrest between elective and nonelective cases. 13
During the study, 91.7% (11/12) of anaesthesia-related cardiac arrests occurred in children 3 years of age or less, indicating that this group has a high risk of peri-operative complications. 16
In our study, the number of cardiac arrests was higher in children undergoing cardiac procedures. These findings are in agreement with several studies on peri-operative complications in children. 8,10,13,16 The proportion of anaesthesia-attributable cardiac arrest was greater in children undergoing noncardiac procedures. By expanding a special team, well trained paediatric anaesthesiologists were increasingly available for all other surgical areas, and notably, after implementation of a specialised paediatric anaesthesia team, no more cardiac arrests occurred in the noncardiac setting. However, the continued occurrence of cardiac arrest in cardiac procedures after 2013 shows that cardiac intervention is still a risk area in our hospital, but we cannot provide the exact individual case-load of the specialised paediatric anaesthesia group. However, as paediatric anaesthetists were more often available for paediatric cases in all surgical areas of our hospital since 2014, we expect that the individual case-load remained constant or even increased despite an increasing number of physicians in the paediatric group. From the literature, a minimum of 200 paediatric cases annually, 26 or 50 cases annually in children less than 3 years of age, 27 are recommended to acquire sufficient competence. Recent studies showed that longer years of experience and a high individual case-load in paediatric anaesthesia have beneficial effects on complication rates and incidences of cardiac arrest. 13,16
Respiratory and airway problems accounted for most anaesthesia-attributable cardiac arrests, followed by cardiovascular events. Respiratory or cardiovascular events were major causes in most previous studies of peri-operative paediatric cardiac arrest. 6–11,13 Both preventable cardiac arrests due to medication errors occurred in the first period (2008 to 2013). This might be a further indicator that management of anaesthesiological paediatric care improved after implementation of a specialised training and team.
The findings of our present analysis and the results of recent studies stress the importance of educational measures and overall quality improvement in paediatric anaesthesia. 16,28,29
Seven children did not survive cardiac arrest to hospital discharge. All nonsurvivors were in the group with cardiac arrest unrelated to anaesthesia, suggesting that the chance of surviving anaesthesia-attributable cardiac arrest might be higher than for cardiac arrest unrelated to anaesthesia.
As data on survival to hospital discharge were derived from the hospital information system, we cannot comment on neurological outcome.
The strengths of our study are a large study population and a clear and important clinical endpoint (cardiac arrest). Cardiac arrest is an established endpoint used in many studies and can serve as a quality indicator. 5,6,8,9,11,13,24,30,31 However, cardiac arrest is a rare peri-operative event and studies also need to analyse other complications in paediatric anaesthesia (e.g. respiratory problems, medication errors etc.). Furthermore, a standardised scoring system 22 was used which enables direct comparison with some other studies in the field of peri-operative complications. 5,15,32 Our data from a tertiary care university hospital represent a broad anaesthesiological spectrum and a typical hospital paediatric patient mix including cardiac procedures. Thus, our results might be representative for teaching hospitals with a variably experienced staff in paediatric anaesthesia.
The current study has some important limitations. As it is a retrospective and observational analysis, we are not able to comment on causality or to evaluate specific effects of different parts of the intervention. Furthermore, we cannot define an exact point in time from which our measures took an effect. Even though our anaesthesia protocol is machine-readable, only a few fields (i.e. ASA physical status, age, emergency) were reliably filled out. Therefore, we had to limit ourselves to these parameters for the analysis, and we cannot comment on the effect of other variables, such as surgical complexity or comorbidities. Furthermore, we cannot exclude the possibility that other factors may have changed during the study period and contributed to the reduction of incidences of cardiac arrest, especially as frequencies of cardiac arrest appeared to be lower in the period 2011 to 2013 compared with 2008 to 2010.
Moreover, as we depend on reporting by our staff anaesthesiologists, it is possible that some critical incidents were missed. We chose a time period of 24 h postoperatively and probably not all postoperative complications in outpatients were captured. Therefore, we might have missed some incidents in the late peri-operative period. However, our analysis focuses on anaesthesia-attributable cardiac arrest, and most anaesthesia-related complications are likely to appear in the intra-operative or early postoperative period.
Furthermore, critical incident reports were reviewed by institutional members. Therefore, it is possible that not all incidents were classified correctly as attributable or unrelated to anaesthesia. The differences in study design, observation periods and definitions of peri-operative complications or outcomes limit the comparability of the different studies in this field. So far, there is no consensus on documenting complications and defining anaesthesia-related mortality. 33 Finally, as a single-centre study, our results may not be generalisable.
Children are at increased risk of peri-operative cardiac arrest. Young age, ASA physical status grade and cardiac procedures contribute as risk factors. Specialised paediatric anaesthesia staff and implementation of paediatric anaesthesia training guidelines are mandatory to handle high-risk procedures and may be an important factor in further paediatric peri-operative cardiac arrest risk reduction.
Acknowledgements relating to this article
Assistance with the study: none.
Financial support and sponsorship: this study was funded by internal sources only.
Conflicts of interest: none.
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