postoperative nausea and vomiting prediction

1. Can PONV be predicted?
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Risk factor analysis

2. • Use of prophylactic antiemetics should be based on
valid assessment of the patients risk for POV or
PONV.
• In other words....antiemetic prophylaxis shouild be
used only when the patient individual risk is
sufficiently high.
• Estimate:baseline risk * baseline risk reduction
resulting from prophylaxisUse of prophylactic
antiemetics should be based on
• This approach produces a clinically meaningful
decrease in the risk of PONV
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3. Simplified Scoring System
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Risk Factors
• Female
• Nonsmoking history
• Hx of motion sickness or PONV
• Use of postoperative opioids
Incidence of PONV
Risk Factors Incidence
0 10%
1 21%
2 39%
3 61%
4 79% Apfel CC et al. Anesthesiology 1999;91:693-700.

4. Simplified scoring system from Apfel for
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adults
• For every risk factor the sum is additive:
• Point 0 risk 10%
• Point 1 risk 20%
• Point 2 risk 40%
• Point 3 risk 60%
• Point 4 risk 80%

5. Simplified risk score from Apfel et al. to predict the
patients risk for PONVin adults . When 0, 1, 2, 3, or 4 of the depicted independent
predictors are present, the corresponding riskfor PONV is approximately 10%, 20%,
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40%, 60%, or 80%.
Figure 1

6. Simplified scoring system from Eberhardt
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39 di Samba for children
• Surgery> 30 min
• Age> 3
• Strabismus surgery
• Hx of POV or POnv in relatives
• Sum 0......4
• Risk 10%,10%,30%,55%,70%

7. Simplified risk score from Eberhart et al. (39) to predict the
risk for POV in children. When 0, 1, 2, 3, or 4 of the depicted
independent predictors are present, the corresponding risk
for PONV is approximately 10%, 10%, 30%, 55%, or 70%.
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8. Particular medical risk
• more liberal prophylaxis is appropriate for patients in
whom vomiting poses a particular medical risk:
• wired jaws
• increased intracranial pressure
• gastric or esophageal surgery
• when the anesthesia care provider determines the
need
• or the patient has a strong preference to avoid PONV
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9. Servizio di Anestesia e
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Sinclair et al.Can PONV be
predicted?Anesthesiology 1999;91:109-18
• 17,638 consecutive ambulatory surgical patients;>90% ASA I /II
• 5,812 men and 11,826 women
• mean (± SD) age of 46.7 ± 21.2 yr.
• prospectively studied during a 3-yr period
• ASU of The Toronto Hospital, Western Division
• telephone interview 24 h after operation was obtained.
• Preoperative patient characteristics and intraoperative variables were
documented on specifically designed, standardized adverse-outcome
check-off forms.
• i.v.2—4 mg morphine for pain relief and 25—50 mg dimenhydrinate
for nausea or vomiting.
• Overall PONV incidence 4.6%:9.1 % at 24 hrs interview.

10. Independent predictors of PONV
Sinclair et al.Can PONV be predicted?Anesthesiology 1999;91:109-18
• age A 10-yr increase in age was associated with a 13% decrease in the likelihood of PONV.
• sex Men had one third the risk for PONV compared with women.
• smoking status Smokers had two thirds the risk for PONV compared with nonsmokers
• history of previous PONV, had a threefold increase in the likelihood PONV compared with patients with no
previous PONV.
• type of anesthesia: General anesthesia increased the likelihood of PONV 11 times compared with other types of
anesthesia.
• duration of anesthesia, direct association between the duration of anesthesia and the risk for PONV. A 30-min
increase in duration predicted a 59% increase in the incidence of PONV
• type of surgery :
– plastic surgery had a sevenfold increase in the risk for PONV.
– orthopedic shoulder surgery, ophthalmologic, or ENT procedures had a four- to sixfold increase.
– orthopedic (nonshoulder) and gynecologic (non-D&C) procedures had a threefold
increase in the risk for PONV. Compared with the reference group, which includes
general surgery, gynecologic dilation and curettage (D&C), urologic surgery,
neurosurgery, and chronic pain blockENT
– dental surgery 14.3%, orthopedic 7.6%,plastic surgery 7.4%.Urologic, gynecologic,
neurologic, or general surgery had an incidence of PONV corresponding to the overall
average 4%
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•

11. Logistic regression da:Sinclair et al.Can PONV be
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predicted?Anesthesiology 1999;91:109-18
• P=1/1+e esponente
• con il segno neg. all’esponente la probabilità aumenta perché e elevato
ad esp negativo diminuisce sempre + con il risultato che 1+e tende a 1 e
dunque P=1/1,ossia 100%
• Con il segno positivo all’esponente e aumenta sempre + e allora 1+e
aumenta e dunque il denominatorer dell’equazione aumenta e dunque
1/un numero in aumento fa scendere la probabilità perché viene
1/5,cioè 20%,1/10=10%,ecc…..
• Esponente=-5,97+(-0,14 *age)+(-1,03*sex)+
(-0,42*smoke)+(1,14*PONV history)+
(0,46*duration)+(2,36*GA)+(1,48*ENT)+
(1,77*ophtalm)+(1,90*plastic)+(1,20 Gynecol non DC)+(1,04 ort knee)+(1,78*ortshoulder)+(0.94
ort other)
• where Age = age in years/10; Sex = 1 if male and 0 if female; Smoke = 1 if smoker and 0 if nonsmoker; PONV
History = 1 if previous PONV and 0 if no previous PONV; Duration = duration of surgery in 30-min increments;
GA = 1 if general anesthesia and 0 if other type of anesthesia; ENT = 1 if ENT and 0 if other type of surgery;
Ophthalm = 1 if ophthalmology and 0 if other type of surgery; Plastic = 1 if plastic surgery and 0 if other type
of surgery; GynNonDC = 1 if gynecologic non D&C procedure and 0 if other type of surgery; OrtKnee = 1 if
orthopedic procedure involving knee and 0 if other type of surgery; OrtShoulder = 1 if orthopedic procedure
involving the shoulder and 0 if other type of surgery; OrtOther = 1 if orthopedic procedure involving neither
knee nor shoulder and 0 if other type of surgery.

12. Importance of the work by Sinclair et
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al…
• Fitting the model to the data, we can obtain the
maximum likelihood estimate of the parameters for
each variable. Based on the maximum likelihood
estimates from the final models, it is possible to
calculate an expected risk of occurrence of the
specific adverse event for any patient.
•

13. • Appendix 1
• Logistic regression is used to model the relation between explanatory variables and binary outcome variables. The logistic regression
modeling assumes that the probability of an event (i.e., the occurrence of the outcome) is associated with the values of the explanatory
variables in the following way:
•
• where
•
• where p = probability of the occurrence of the outcome, xi = value of the ith independent variable, and bi events for any patient =
parameter estimates for the ith variable.
• Fitting the model to the data, we can obtain the maximum likelihood estimate of the parameters for each variable. Based on the
maximum likelihood estimates from the final models, it is possible to calculate an expected risk of occurrence of the specific adverse
event for any patient.
• Examples
• The risk for patient 1, a 30-yr-old woman with a history of smoking and previous PONV undergoing a 1-h shoulder (orthopedic)
operation with general anesthesia is 35.2%.
•
• The risk for patient 2, a 40-yr-old nonsmoking man with no previous PONV undergoing a 1-h knee arthroscopy (orthopedic) without
general anesthesia is 0.4%.
•
• The risk for patient 3, a 70-yr-old smoking man with no previous PONV undergoing a 1-h cataract surgery (ophthalmologic) without
general anesthesia is 0.3%.
•
• The risk for patient 4, a 32-yr-old nonsmoking woman with previous PONV undergoing a 30-min laparoscopy (gynecologic) with general
anesthesia is 22.1%
•
• The risk for patient 5, a 22-yr-old woman with a history of smoking and previous PONV undergoing a 90-min bilateral breast
augmentation (plastic surgery) with general anesthesia is 52%.
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14. Strategies to Reduce Baseline
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Risk
• Avoidance of general anesthesia by the use of regional
anesthesia (11,16) (randomized, controlled trial, RCT)
• Use of propofol for induction and maintenance of
Anesthesia(4,14,41,42) (RCT/systematic review, SR)
• Avoidance of nitrous oxide (3,4,43,44) (RCT/SR)
• Avoidance of volatile anesthetics (15,28) (RCT)
• Minimization of intraoperative (SR) and postoperative
• opioids (3,13,15,17,18,20,28,43) (RCT/SR)
• Minimization of neostigmine (19,45) (SR)
• Adequate hydration (46) (RCT)

15. Servizio di Anestesia e
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Risk Factors
• Non-anesthetic factors
• Anesthetic related
factors
• Postoperative factors

16. Risk factors da Samba 2007:1
• Patient specific
– Female gender
– Non smoking status
– Hx of ponv/motion sickness
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17. Risk factors da Samba 2007:2
• Anesthetic risk factors
– Use on intraop volatile anesth
– Use on intraop and postop opioids
– Use of intraop N2O
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18. Risk factors da Samba 2007:3
• Surgical risk factors
– Duration of surgery
– Each 30 min increase in duration of surgery oncreases the
risk by 60%,so thyat a baseline risk of 10% increases to
16% after 30 min
– Type of surgery
Laparoscopy;,laparotomy;breast,strabismus,plastic,maxi
llofacial,gynecological,abdominal,neurologic
,opthalmologic,urologic
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19. Non-anesthetic Factors
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Risk Factors
• Age
• Gender
• Body habitus
• Hx motion sickness
• Hx PONV
• Anxiety
• Concomitant disease
• Operative procedure
• Duration of surgery

20. Anesthetic Related Factors
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Risk Factors
• Preanesthetic medication
• Gastric distension
• Gastric suctioning
• Anesthetic technique
• Anesthetic agents

21. Postoperative Factors
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Risk Factors
• Pain
• Dizziness
• Ambulation
• Oral intake
• Opioids

22. Postoperative Nausea and Vomiting:
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Anesthetic Related Factors
• Nitrous oxide
• Volatile anesthetics
• NMB reversal
• Propofol

23. Omitting nitrous oxide from general anesthesia:
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Risk Factors
Nitrous Oxide and PONV
• Decreases POV significantly only if the baseline
risk is high
• Does not affect nausea or complete control of
emesis
• Increases the incidence of intraoperative
awareness
Tramer et al. BJA 1996;76:186-193

24. IS PONV incidence different between
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LMA and ETT?
• Joshi GP, Inagaki Y, White PF, Taylor-Kennedy
L, Wat LI, Gevirtz C, McCraney JM, McCulloch
DA: Use of the laryngeal mask airway as an
alternative to the tracheal tube during
ambulatory anesthesia. Anesth Analg 85:573–
7, 199

25. Risk Factors
Volatile anesthetics
Risk Factors OR* CI
Volatile
anesthetics
isoflurane 3.41 2.18; 5.37
sevoflurane 2.78 1.79; 4.31
enflurane 3.11 1.98; 4.88
Apfel et al. BJA 2002;88:659-668
* Compared to propofol
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26. Servizio di Anestesia e
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Risk Factors
Reversal of Neuromuscular Block
• Omitting neostigmine may have a clinically
relevant antiemetic effect when high doses
are used
• Omitting NMB antagonism introduces a
non-negligent risk of residual paralysis
even when short acting NMB agents are
used
Tramer MR, Fuchs-Buder T. BJA 1999;82:379-386

27. Servizio di Anestesia e
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Risk Factors
Propofol and PONV
All Control Event Rates
Early Late
NauseaVomitingAnyNauseaVomitingAny
Induction 9.3* 13.7* 20.9 50.114.9NA
Maintenance 8* 9.2* 6.2* 5.8* 10.1* 10
20% - 60% Control Event Rate
Early Late
NauseaVomitingAnyNauseaVomitingAny
Induction 5.0* 7.0* 14 28 10 NA
Maintenance 4.7* 4.9* 4.9* 6.1* 8.3* 7.1
Tramer et al. BJA 1997;78:247-255
Analysis by NNT

28. Servizio di Anestesia e
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Risk Factors
Antiemetic Effects of Propofol
Investigations Randomized Double-Blind Placebo-Controlled Effective
Chemotherapy Induced Emesis
Scher 1992 no no no yes
Borgeat 1993 no no no yes
Borgeat 1994 no no no yes
PONV
Campbell 1991 yes yes yes no
Borgeat 1992 yes yes yes yes
Ewalenko 1996 yes yes yes yes
Montgomery 1996 yes yes yes no
Scuderi 1996 yes yes yes no
Gan 1997 no no no yes
Gan 1999 yes yes yes yes

29. Logistic Regression
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Risk Factors
Palazzo M, Evans R. Logistic regression analysis of fixed patient
factors for postoperative sickness: a model for risk assessment. Br J
Anaesth 1993;70:135-40.
Koivuranta M, Läärä E, Snåre L, Alahuhta S. A survey of postoperative
nausea and vomiting. Anaesthesia 1997;52:443-49.
Apfel CC, Greim CA, Haubitz I, et al. A risk score to predict the
probability of postoperative vomiting in adults. Acta Anaesthesiol Scand
1998;42:495-501.

30. Logistic Regression
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Risk Factors
• Younger age
• Nonsmoking history
• Female
• Hx of motion sickness
• Hx of PONV
• Increased duration of operation

31. Servizio di Anestesia e
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Problems............
• to separate independent factors vs dependent
factors................
• No risk model can actually predict the
likelihood of an individual having PONV;risk
models only allow clinicians to etimate the risk
of PONV among patients groups

32. Servizio di Anestesia e
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PPOONNVV
ffattttorrii dii rriischiio
ddoonnnnee
ggiioovvaannii
età
fer tile
ggrraavviiddee
post
partum
iinntteerrvveennttii
mus coli
ex traocular i
orecc hio
medio
pelv i
femm.in
laparoscopia
deambulazione
precoce
bbaambbiinnii
soggetti
a
cinetos i
pregres so
PONV
ffaarrmaaccii
ooppppiiooiiddii
anestetici
inalatori
Neurosurg N2O
Breast surg
Laparotomy
Plastic surg.
Non
smokers