Table 1 Summary of patient attributes

Demographic:

age

patient age

gender

patient gender

weight

patient weight

Biomedical:

pulse

heart rate

sbp

systolic blood pressue

dbp

diastolic blood pressure

DM

if patient is diabetic

HT

if patient has hypertension

AMI

if patient has acute myocardial infarction

ASA_CLASS ^*

1: healthy

2: mild systemic disease

3: major systemic disease

4: life-threatening disease or condition

5: not expected to survive

6: donor

OP-related:

OP_CLASS

surgical type:

1: intrathoracic

2: upper intra-abdominal

3: lower intra-abdominal

4: laminectomy

5: major joints

6: limbs

7: head& neck

8: others

op_time

surgical duration

URGENCY

E: emergency surgery

R: regular surgery

ANS_WAY

SA: spinal anesthesia

GA: general anesthesia

LE: lumbar epidural anesthesia

NB: nerve blockade

PCA-related:

loading_dose

analgesia taken before PCA treatment

sucess_p_1hr~ sucess_p_24hr

number of successful PCA demands in 1^st–24^th h

failure_p_1hr~ failure_p_24hr

number of PCA demands that fail in 1^st–24^th h

pcadose_1hr~ pcadose_24hr

total PCA dose in 1^st–24^th h

contidose_1hr~ contidose_24hr

total continuous dose in 1^st–24^th h

readjustcount_1hr~ readjustcount_24hr

number of PCA readjustment in 1^st–24^th h

p_timediff_mean_1hr~ p_timediff_mean_24hr

mean of time gap between two consecutive PCA demands

p_timediff_var_1hr~ p_timediff_var_24hr

variance of time gap between two consecutive PCA demans

pcamode_set_1hr~ pcamode_set_24hr

setting of PCA mode:

(a) PCA and continuous

(b) PCA only

pcadose_set_1hr~ pcadose_set_24hr

PCA dose setting in 1^st–24^th h

lockout_set_1hr~ lockout_set_24hr

setting of minimum time gap between two adjacent PCA demands in 1^st–24^th h

4hrlimit_set_1hr~4hrlimit_set_24hr

setting of maximum dosage allowed for every 4 h in 1^st–24^th h