The Japanese Epidemiologic Study for Perioperative Anaphylaxis, a prospective nationwide study: allergen exposure, epidemiology, and diagnosis of anaphylaxis during general anaesthesia.

BACKGROUND: Diagnosis of perioperative anaphylaxis is often challenging. This study describes the utility of a newly developed tool for identifying patients with a high possibility of anaphylaxis, and aimed to investigate the frequency of anaphylaxis with each drug during the perioperative period in Japan. METHODS: This study included patients with anaphylaxis of Grade 2 or higher severity during general anaesthesia at 42 facilities across Japan in 2019 and 2020. We developed and adopted a unique objective evaluation tool yielding a composite score for diagnosing anaphylaxis, which includes the results of skin tests and basophil activation tests, and clinical scores for perioperative anaphylaxis. The number of cases using each drug and the total number of anaphylaxis cases were investigated to calculate the frequency of anaphylaxis. RESULTS: General anaesthesia was performed in 218 936 cases, which included 55 patients with suspected perioperative anaphylaxis. The developed composite score diagnosed 43 of them with a high probability of anaphylaxis. The causative agent was identified in 32 cases. Plasma histamine levels showed high diagnostic accuracy for anaphylaxis. The top causative agents were rocuronium (10 cases in 210 852 patients, 0.005%), sugammadex (7 cases in 150 629 patients, 0.005%), and cefazolin (7 cases in 106 005 patients, 0.007%). CONCLUSIONS: We developed a composite tool to diagnose anaphylaxis, and found that the combination of tryptase levels, skin testing, and basophil activation testing results and clinical score improved the certainty of anaphylaxis diagnosis. The incidence of perioperative anaphylaxis in our study was 1 in about 5000 general anaesthesia cases. CLINICAL TRIAL REGISTRATION: UMIN000035350.

A case of unexpected impaired oxygenation due to intraoperative pneumothorax: an adverse event associated with respiratory management with spontaneous respiration in a patient with esophagobronchial fistulae.

BACKGROUND: Respiratory management in patients with esophagobronchial fistulae is challenging since positive pressure ventilation (PPV) may not be feasible due to air leaks and possible risks for regurgitation and aspiration of gastric contents. We and others have previously reported that spontaneous respiration may be one of the good options of respiratory management during general anesthesia in those patients. However, adverse events associated with this respiratory strategy have not been reported previously. We experienced a 77-year-old male patient who suffered unexpected impairment of oxygenation due to intraoperative pneumothorax, which was assumed to have been exacerbated by spontaneous respiration during esophageal bypass surgery. CASE PRESENTATION: The patient was planned to undergo esophageal bypass surgery for esophagobronchial fistulae associated with malignant esophageal cancer. Both of two esophagobronchial fistulae were located in the proximal part of the left main bronchus. For the risks of air leaks and aspiration associated with PPV and further damage to the tissue around the fistulae, we decided to maintain spontaneous respiration under general anesthesia and obtain abdominal muscle relaxation with epidural anesthesia. After catheterization of epidural anesthesia, the patient was sedated with 35 mg of intravenous pethidine and was nasotracheally intubated under bronchoscopic guidance. We confirmed that the tip of the tracheal tube was located above the carina. Then anesthesia was induced and maintained with sevoflurane so that his spontaneous respiration could be maintained thereafter. His spontaneous respiration was assisted with 3 cmH2O of pressure support. Approximately 60 min into the surgery, percutaneous arterial oxygen saturation (SpO2) suddenly dropped from 99 to 89% with an inspiratory fraction of oxygen of 0.4. We assumed that lung atelectasis associated with airway secretion or pulmonary soiling was the most likely reason for impaired oxygenation; however, arterial oxygenation only partially regained even after they were suctioned. After the completion of the surgery, chest X-ray revealed right pneumothorax. After a chest drainage tube was inserted, right pneumothorax was ameliorated and SpO2 returned to the baseline level. CONCLUSIONS: Although spontaneous respiration may be useful in a patient with esophagobronchial fistulae, oxygenation can be impaired more seriously than PPV in case intraoperative pneumothorax occurs.