Epidemiological Investigation of Unplanned Intensive Care Unit Admissions From the Operating Room After Elective Surgery: A Nationwide Observational Study in Japan
Authors: Omoto Miki , Aoki Yoshitaka , Nakajima Mikio , Kurita Tadayoshi , Kaszynski Richard H , Kato Hiromi , Mimuro Soichiro , Igarashi Hiroshi , Nakajima Yoshiki 
Published: February 2025

BACKGROUND:
Over 75% of surgeries worldwide are elective and unplanned ICU admissions after these surgeries pose a major—albeit rare—challenge. However, few epidemiological studies have focused on patients requiring unplanned ICU admission directly from the operating room after elective surgeries are lacking. This study uses the Japanese Intensive Care Patient Database (JIPAD) to describe unplanned ICU admissions after elective surgeries.

METHODS:
We conducted a multicenter retrospective cohort study using data from the JIPAD from April 2015 to March 2022, focusing on patients with unplanned ICU admissions after elective surgery. Collected variables included patient characteristics, treatments, outcomes, reasons for ICU admission, and type of surgery. We categorized the reasons for ICU admission into 9 types: anaphylaxis, hemorrhage, anesthesia-related complications, respiratory-related complications, cardiovascular-related complications, neurological-related complications, surgical-related complications, electrolyte/acid-base abnormalities, and unknown causes. The type of surgery was classified using JIPAD definitions.

RESULTS:
Among 141,969 patients in the JIPAD who underwent elective surgery, 2666 patients (1.9%) required an unplanned ICU admission. Cardiac arrest before ICU admission occurred in 52 patients (2.0%), the median APACHE III score was 51, and 1218 patients (45.7%) required postoperative mechanical ventilation. The median hospital stay for patients with unplanned ICU admission was 21 days and in-hospital mortality was 3.3% (88/2666). The most common reason for ICU admission was respiratory complications (n = 440, 16.5%), followed by hemorrhage (n = 377, 14.1%). Cardiovascular-related complications had the highest in-hospital mortality at 6.8% (20/294). Hospital mortality exceeded ICU mortality, suggesting that patients expected to derive limited benefit from intensive care may have been transitioned out of the ICU to accommodate other patients with greater need. The most frequent surgeries requiring unplanned ICU admission were for gastrointestinal neoplasms (n = 464, 17.4%), followed by orthopedic surgeries (n = 303, 11.4%). Anaphylaxis occurred across a broad spectrum of surgeries. Respiratory-related complications were common in patients with other respiratory diseases and accounted for over half of the total number of cases according to surgery type. Neurological-related complications were most frequent in craniotomies for neoplasms.

CONCLUSIONS:
In our review of a nationwide ICU database from 2015 to 2022 we identified a 1.9% rate of unplanned ICU admission and found that mortality varied according to the reasons for ICU admission. Respiratory-related complications were most common, and cardiovascular complications were most associated with in-hospital mortality. Further research may help us to better understand the epidemiology of unplanned ICU admission after surgery.