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Table 1 Characteristics of cohort

From: The cumulative duration of bispectral index less than 40 concurrent with hypotension is associated with 90-day postoperative mortality: a retrospective study

Variables

All patients (n = 1862)

Age (year)

63.1 (19–91)

Male sex

1088 (58.4%)

Body mass index (kg/m2)

23.4 (3.5)

Category of surgical procedures

 Stomach

492 (26.4%)

 Colorectal

719 (38.6%)

 Hepatic

154 (8.3%)

 Biliary-pancreas

497 (26.7%)

Type of anesthesia

 Total intravenous anesthesia

865 (46.5%)

 Volatile agent

997 (53.5%)

Duration of anesthesia (min)

196.6 (104.4)

BIS derived variables

 bis40_dur (min)

70.5 (73.2)

 bis40_5min

1701 (91.4%)

 bis20_dur (min)

0.5 (4.2)

 bis20_5min

35 (1.9%)

 eegsup_dur (min)

1.6 (6.6)

 eegsup_5min

134 (7.2%)

 bis40map50_dur (min)

0.34 (0.92)

 bis20map50_dur (min)

0.01 (0.11)

map50_dur (min)

0.8 (1.7)

Past medical history

 Aortic stenosis

10 (0.5%)

 Congestive heart failure

6 (0.3%)

 Coronary artery disease

98 (5.3%)

 Hypertension

706 (37.9%)

 Peripheral vascular occlusive disease

6 (0.3%)

 Dysrhythmia

61 (3.3%)

 Chronic obstructive pulmonary disease

46 (2.5%)

 Pulmonary hypertension

7 (0.4%)

 Stroke

70 (3.8%)

 Malignancy

1368 (73.5%)

 Diabetes

398 (21.4%)

 Sleep apnea

3 (0.2%)

Social history

 Current smoker

255 (13.7%)

 Regular alcohol ingestion

449 (24.1%)

ASA classification

 I

456 (24.5%)

 II

1181 (63.4%)

 III

221 (11.9%)

 IV

4 (0.2%)

Laboratory tests

 Hemoglobin (g/dL)

10.5 (3.7)

 Albumin (g/dL)

3.7 (1.0)

  1. Continuous variables are presented with their mean (standard deviation) except age [mean (range)], and categorical variables are presented with their number (percentage)
  2. Abbreviations: BIS Bispectral index; bis40_dur, cumulative time in which BIS < 40; bis40_5min, incidence in which cumulative time of BIS < 40 lasted > 5 min; bis20_dur, cumulative time in which BIS < 20; bis20_5min, incidence in which cumulative time of BIS < 20 lasted > 5 min; EEG Electroencephalogram; eegsup_dur, cumulative time in which patient’s EEG was suppressed; eegsup_5min, incidence in which cumulative time of EEG suppression lasted > 5 min; MAP Mean arterial pressure; bis40map50_dur, cumulative time that BIS < 40 and MAP < 50 mmHg simultaneously; bis20map50_dur, cumulative time that BIS < 20 and MAP < 50 mmHg simultaneously; map50_dur, cumulative time that MAP < 50 mmHg; ASA The American Society of Anesthesiologists physical status