### Description

Sinclair et al developed an equation that can be used to predict the probability of postoperative nausea and vomiting (PONV) for a patient having outpatient surgery. This can help the anesthesiologist identify patients who may need antiemetic therapy. The authors are from the University of Pittsburgh.

Parameters:

(1) age in years

(2) sex

(3) smoking status

(4) history of PONV

(5) duration of surgery

(6) anesthesia type

(7) type of surgery

Parameter

Finding

Points

age

age in years

(age) / 10

sex

female

0

male

1

smoking status

nonsmoker

0

smoker

1

history of previous PONV

no

0

yes

1

duration of surgery

duration in minutes

(duration) / 30

anesthesia type

other than general

0

general

1

ENT surgery done

no

0

yes

1

ophthalmologic surgery done

no

0

yes

1

plastic surgery done

no

0

yes

1

gynecologic surgery other than D & C done

no

0

yes

1

orthopedic surgery to knee done

no

0

yes

1

orthopedic surgery to shoulder done

no

0

yes

1

orthopedic surgery to site other than knee or shoulder

no

0

yes

1

where:

• Sometimes smoking status infers cigarette smoking only.

• The duration of surgery is based on 30 minute increments. I did not round this in the implementation.

• It appears that the system takes into account the possibility of more than 1 procedure being done while a person is under anesthesia. I am not sure if there should be an adjustment if both knees or shoulders were done at the same time.

probability of PONV =

= 1 / (1 + EXP((-1) * X))

X =

= (-5.97) – (0.14 * (points for age)) – (1.03 * (points for sex)) – (0.42 * (points for smoking status)) + (1.14 * (points for PONV history)) + (0.46 * (points for duration of surgery)) + (2.36 * (points for general anesthesia)) + (1.48 * (points for ENT surgery)) + (1.77 * (points for ophthalmologic surgery)) + (1.90 * (points for plastic surgery)) + (1.20 * (points for gynecologic surgery)) + (1.04 * (points for orthopedic surgery to knee)) + (1.78 * (points for orthopedic surgery to shoulder)) + (0.94 * (points for orthopedic surgery other than knee or shoulder))