Introduction

The potential long-term impact of surgery and anesthesia has been progressing over the past 20 years with a significant interest and academically challenging research activity on the several aspects of neurodevelopment [1, 2]. Although anesthesiologists are currently facing the likelihood that detectable developmental anesthetic neurotoxicity may not exist in a single and short exposure to general anesthesia in early life [3,4,5,6], they have not yet been able to prove or disprove this nonexistence [7].

In addition to long-term neurodevelopmental outcome, anesthesiologists still need to pay sufficient attention to immediate perioperative risks. Pediatric anesthesia-related mortality has decreased to approximately 1 out of 10,000 children who receive anesthetics (0.01%) in high-income countries [8,9,10,11,12,13]. However, the rates of pediatric anesthesia-related severe adverse events remaining approximately 2–8% even in high-income countries [12,13,14,15,16]. A recent prospective cohort study, the Anesthesia Practice in Children Observational Trial (APRICOT), revealed a relatively high overall incidence (5.2%) of perioperative severe adverse events with large variability in anesthetic practices across 33 European countries [17].

Subsequently, there are rising trends of minimally invasive surgeries including robotic surgery [18] and sedation or anesthesia outside the operating room [19,20,21]. Although these practices are not different in pediatric and adult patients, they may offer unique challenges, requiring the anesthesiologists’ scrupulous knowledge and comprehension on the associated anatomical and physiological considerations in pediatric patients [22].

Given the challenges observed in studies related to anesthetic impact on neurodevelopment, children offer unique opportunities for anesthesiologists to consider lifelong consequences of any early intervention. Pediatric perioperative issues are facing challenges which require sustained efforts from anesthesiologists. However, training in pediatric anesthesia is reaching a turning point in Japan.

Volume–outcome association in pediatric anesthesia

Training in the field of anesthesia is generally implemented, which comprises direct teaching, targeted supervision, and overall acquisition of knowledge, skills, and attitudes essential to the safe and effective delivery of anesthesia [23]. Basically, the more you are trained, the more you can advance from a novice to a competent trainee. Hence, training is the predominant factor determining the advancement from a novice to a competent trainee. However, higher-level development to an expert requires an additional challenge, such as experiences. In short, experience consolidates knowledge and helps to establish safe practice [24].

A previous French postal survey reported the association between the number of anesthesia-related complications and the volume of pediatric anesthetic practices per year, showing less caseloads per anesthesia provider were associated with more postoperative complications [25]. The APRICOT has also shown that senior anesthesiologists had 1% fewer critical respiratory events per year of experience and that facilities with a higher caseload had a lower rate of critical events [17]. A sub-analysis using the UK data only in the APRICOT demonstrated that the lower incidence of cardiovascular and respiratory complications could be partly attributed to more experienced dedicated pediatric anesthesia providers managing the higher-risk patients, whereas it did not show significant inverse volume–outcome effects in perioperative critical events among institutions [26]. Hence, controversies in volume–outcome association per anesthesia provider or per institution in terms of the incidence of perioperative adverse events exist. However, some experts recommended a minimum caseload of 200 pediatric anesthesia practices per provider per year to reduce the incidence of complications [25]. Practically, setting a minimum caseload volume is considered complicated, and the exact number is difficult to define and apply for all pediatric anesthetic procedures.

Recent changes impacting on anesthesia training in Japan

Training in pediatric anesthesia has recently experienced significant organizational and politically driven changes in Japan.

One change is the introduction of compulsory pediatric anesthesia training as well as cardiac, thoracic, neurosurgical, and obstetric anesthesia training as a prerequisite for the anesthesia board examination. During the 4-year anesthesiology residency, all anesthesiology trainees need to provide anesthesia for at least 600 cases. In the 600 cases, a minimum number is set for each specialty: the number of compulsory pediatric cases is 25 for children aged less than 6 years. Every university hospital has been required to plan pediatric anesthesia training programs, and simultaneously, children’s hospitals have been required to be restructured to meet the changing educational demands. Among the minimum required number of pediatric cases in anesthesiology trainees in the USA, Europe, and Japan, that in Japan seems to be the most limited [27]. There is a wide variability in the number of procedures performed among anesthesiology trainees until acceptable safe anesthetic procedures are attained [28]. Therefore, it would be difficult to define the “magic number” for anesthesiology trainees to attain sufficient knowledge and skills to provide safe pediatric anesthetic practices. However, the minimum caseload of 25 pediatric anesthetic practices during residency may be insufficient for an anesthesiologist to comfortably provide care even for children with ASA-PS class I or II [29].

Another change in anesthesia training, not only in pediatric but also in general, is that the introduction of the Japanese Working Time Directive (“Work Style Reform” policy) will predominantly result in reduced total weekly hours even for medical trainees in the future. It must help us maintain the quality of life of medical practitioners. On the contrary, it may reduce the total time of exposure of anesthesiology trainees to clinical pediatric anesthesia cases. Practically, extending the hours worked or the length of training programs is not necessarily a sustainable solution for anesthesiology training. The concept of “making every moment count” is important. Meanwhile, lack of experiences and clinical exposures may result in less independent practices and loss of self-confidence of anesthesiologist trainees, eventually leading to increasing perioperative complications and growing concerns over patient safety [17, 25, 26].

Possible lower caseload per anesthesia provider in the future

In addition to the likely reduced working hours, there are other issues that may also have an impact on the caseload of pediatric anesthetic practices per provider.

One is a demographic change toward super-aging society with fewer children. The decrease in the fertility rate and marriage rate has accelerated a shrinking, aging population with fewer children in Japan [30]. Hence, Japan has focused its policies on the work–life balance to increase the birth rate with the introduction of the Japanese Working Time Directive in 2010.

Another is the underdevelopment of centralized medical resources and services for children in Japan. Regionalization of medical resources and services could provide anesthesiology trainees more clinical exposure if they are trained in large centers. However, regionalization has not been well developed in Japan. The infant mortality rate in Japan has been significantly low due to the extensive endeavors of people engaged in executing Japanese policies on maternal and child health since World War II. The low infant mortality rate has been attributed partly to easy access to medical care due to the spatial distribution of small-scale hospitals located to adjacent to dwellings, a well-organized national health insurance system, and inexpensive medical fees [31]. On the contrary, these factors could cause less accumulation of experience per pediatric practitioner [31]. Therefore, the Japan Pediatric Society has proposed the innovative model, which includes regionalization of medical resources. Under this changing circumstances, we have not yet had any definite data based on an anesthesiology workforce analysis in Japan, which should project pediatric anesthesia case-to-pediatric population ratios [32].

Future perspective: new training model and large data analyses

We need to think about innovation of the concept of training model to conquer the possible issue of lower caseload volume. The existing training model emphasizes the quantity and number of fragmented inputs. However, given the lower caseload volume, we may need to change the model to emphasize the quality and value of inputs with integration under the concept of “making every moment count.”

A growing trend in evidence-based medicine is the desire to reduce unnecessary interventions and decrease iatrogenic complications which is undoubtedly better for patient care. In the context of possibly lowering caseload, limiting working hours and decreasing procedure necessity, simulation-based training will be more prioritized. Recent systematic review indicates that simulation training in anesthesia is at least as good as non-simulator training, and is certainly better than no intervention [33]. There is ongoing enthusiasm for simulation-based training in pediatric anesthesia [34,35,36,37,38,39]. In the era of information technology, telesimulation may provide an alternative method to traditional simulation approaches [40, 41], though simulation-based training in anesthesia is fraught with challenges, such as relatively high cost, faculty development, and less tangible patient outcomes [42,43,44,45,46].

In summary, possible lower caseload can be considered a challenge in pediatric anesthesia training in Japan, leading to increased morbidity in the perioperative care of children. Now, we need to consider general approaches to maintain the academic and professional standards in pediatric anesthesia despite the introduction of changed working patterns and reduced hours over the next decade in super-aging society with fewer children. Before then, research projects are expected to comprehend the basic indices, such as perioperative pediatric morbidity and mortality [47] and pediatric anesthesiology workforce survey [32], which require data mining and analytics [48, 49].