Errors, Omissions, and Outliers in Hourly Vital Signs Measurements in Intensive Care

Objective: To empirically examine the prevalence of errors, omissions, and outliers in hourly vital signs recorded in the ICU. Design: Retrospective analysis of vital signs measurements from a large-scale clinical data warehouse (Multiparameter Intelligent Monitoring in Intensive Care III). Setting: Data were collected from the medical, surgical, cardiac, and cardiac surgery ICUs of a tertiary medical center in the United States. Patients: We analyzed data from approximately 48,000 ICU stays including approximately 28 million vital signs measurements. Interventions: None. Measurements and Main Results: We used the vital sign day as our unit of measurement, defined as all the recordings from a single patient for a specific vital sign over a single 24-hour period. Approximately 30–40% of vital sign days included at least one gap of greater than 70 minutes between measurements. Between 3% and 10% of blood pressure measurements included logical inconsistencies. With the exception of pulse oximetry vital sign days, the readings in most vital sign days were normally distributed. We found that 15–38% of vital sign days contained at least one statistical outlier, of which 6–19% occurred simultaneously with outliers in other vital signs. Conclusions: We found a significant number of missing, erroneous, and outlying vital signs measurements in a large ICU database. Our results provide empirical evidence of the nonrepresentativeness of hourly vital signs. Additional studies should focus on determining optimal sampling frequencies for recording vital signs in the ICU.