vitalsign table

The vitalsign table

Patients admitted to the emergency department have routine vital signs taken ever 1-4 hours. These vital signs are stored in the vitalsign table.

Table source: Emergency department information system.

Table purpose: Provides nurse documented vital signs.

Number of rows: 1,564,610

Links to:

• edstays on stay_id

Important considerations

The numeric entries in this table were originally stored as free-text. As a result, the columns required deidentification. Free-text entries which could not be converted trivially were removed. Normally, the application of deidentification in MIMIC-IV is indicated using three underscores (___) to make it clear to users that we have modified the data. We decided it was better to omit this modification than to add confusion and difficulty to users by sharing the majority numeric data as text. As a result, missing data in the numeric columns indicates either deidentified data or no data recorded. However, for the most part, missing data indicates that no information was documented. Below is a table demonstrating how often data were removed for deidentification purposes:

Column	Number of NULL values inserted for deidentification	Number of rows missing data in v2.1
temperature	11048	564968
heartrate	3282	69710
resprate	1330	89393
o2sat	46620	135836
sbp	2854	81256
dbp	2854	81256

From the above, we can see that of the 564968 rows missing a temperature value, 11048 had a free-text value which was deleted during deidentification (~2%).

Table columns

Name	Postgres data type
subject_id	INTEGER NOT NULL
stay_id	INTEGER NOT NULL
charttime	TIMESTAMP(0)
temperature	NUMERIC(10, 4)
heartrate	NUMERIC(10, 4)
resprate	NUMERIC(10, 4)
o2sat	NUMERIC(10, 4)
sbp	INTEGER
dbp	INTEGER
rhythm	TEXT
pain	TEXT

subject_id

subject_id is a unique identifier which specifies an individual patient. Any rows associated with a single subject_id pertain to the same individual.

stay_id

An identifier which uniquely identifies a single emergency department stay for a single patient.

charttime

The time at which the vital signs were charted.

temperature

The patient’s temperature in degrees Farenheit. Some temperatures may be incorrectly documented as Celsius.

heartrate

The patient’s heart rate in beats per minute.

resprate

The patient’s respiratory rate in breaths per minute.

o2sat

The patient’s oxygen saturation measured as a percentage.

sbp, dbp

The patient’s systolic (sbp) and diastolic (dbp) blood pressure measured in millimetres of mercury (mmHg).

rhythm

The patient’s heart rhythm.

pain

The patient’s self-reported level of pain on a scale from 0-10. The pain is documented as free-text and may contain non-numeric entries.