Protocol for a nationwide prospective, observational cohort study of foreign-body airway obstruction in Japan: the MOCHI registry

INTRODUCTION

Foreign body airway obstruction (FBAO) is a major public health issue worldwide. In 2017, there were more than 5000 fatal choking cases in the USA alone, and it was the fourth leading cause of preventable injury-related death in the home and community. In Japan, FBAO is the leading cause of accidental death and with almost 9000 fatalities annually. However, research on FBAO is limited, particularly on the impact of a foreign body (FB) removal manoeuvres by bystanders. The primary objective of this study is to determine the impact of bystander FB removal manoeuvres on 1 month neurological outcome. Our secondary objectives include (1) evaluating the efficacy of a variety of FB removal manoeuvres; (2) identifying risk factors for unsuccessful removal and (3) evaluating the impact of time intervals from incidents of FBAO to FB removal on neurological outcome.

METHODS AND ANALYSIS

We will conduct a nationwide multi-centre prospective cohort study of patients with FBAO who present to approximately 100 emergency departments in both urban and rural areas in Japan. Research personnel at each participating site will collect variables including patient demographics, type of FB and prehospital variables, such as bystander FB removal manoeuvres, medical interventions by prehospital personnel, advanced airway management and diagnostic findings. Our primary outcome is 1 month favourable neurological outcome defined as cerebral performance category 1 or 2. Our secondary outcomes include success of FB removal manoeuvres and complications from the manoeuvres. We hypothesise that bystander FB removal manoeuvres improve patient survival with a favourable neurological outcome.

ETHICS AND DISSEMINATION

This study received research ethics approval from Nippon Medical School Hospital (B-2019-019). Research ethics approval will be obtained from all participating sites before entering patients into the registry. The study was registered at the University Hospital Medical Information Network (UMIN) Clinical Trials Registry.

TRIAL REGISTRATION NUMBER

UMIN 000039907.

New classifications for Life-threatening foreign body airway obstruction

INTRODUCTION

Foreign body airway obstruction (FBAO) is a common medical emergency; however, few studies of life-threatening FBAO have been reported and no standard classification system is available.

METHODS

We retrospectively evaluated patients who presented to the emergency departments of two hospitals and were diagnosed with FBAO. The primary outcome was cerebral performance category (CPC) score at discharge. To establish a new classification system for FBAO, FBAO was classified into three types based on the anatomical and physiological characteristics of the obstructed airway.

RESULTS

A total of 137 patients were enrolled. Median age was 79.0 years. The most common cause of FBAO was meat, followed by bread, rice cake, and rice. Of all patients, 65.7% suffered cardiac arrest and 51.1% died. In contrast, 28.5% had favorable neurological outcomes, defined as CPC 1 and 2. Upper airway obstruction (type 1) was the most common (type 1, 78.1%), while trachea and/or bilateral main bronchus obstruction (type 2, 12.4%) showed significantly higher mortality than type 1 obstruction (82.4% vs 47.7%, P = 0.0078). Patients with unilateral bronchus and/or distal bronchus obstruction (type 3, 9.5%) were significantly more likely to consume a dysphagia diet than type 1 patients (23.1% vs 0%, P < 0.0001).

CONCLUSION

The majority of patients with life-threatening FBAO were elderly and had poor neurological outcomes. Our new classification system divides FBAO into three types, and revealed that mortality was significantly higher with type 2 than type 1 obstruction. This classification system may improve the management of patients with FBAO and assessment of patient outcomes.