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Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Can PONV be predicted?
Risk factor analysis
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
• 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
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Risk Factors
• Female• Nonsmoking history • Hx of motion sickness or PONV• Use of postoperative opioids
Simplified Scoring System
Incidence of PONVRisk Factors Incidence
0 10%
1 21%
2 39%
3 61%
4 79% Apfel CC et al. Anesthesiology 1999;91:693-700.
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Simplified scoring system from Apfel for 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%
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Simplified risk score from Apfel et al. to predict thepatients 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%,
40%, 60%, or 80%.
Figure 1
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Simplified scoring system from Eberhardt 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%
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Simplified risk score from Eberhart et al. (39) to predict therisk for POV in children. When 0, 1, 2, 3, or 4 of the depictedindependent predictors are present, the corresponding risk
for PONV is approximately 10%, 10%, 30%, 55%, or 70%.
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
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
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
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.
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Independent predictors of PONVSinclair 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%
•
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Logistic regression da:Sinclair et al.Can PONV be
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.
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Importance of the work by Sinclair et 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.
•
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
• 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%.
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Strategies to Reduce Baseline 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)
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Risk Factors
• Non-anesthetic factors
• Anesthetic related factors
• Postoperative factors
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Risk factors da Samba 2007:1
• Patient specific
– Female gender
–Non smoking status
–Hx of ponv/motion sickness
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Risk factors da Samba 2007:2
• Anesthetic risk factors
–Use on intraop volatile anesth
–Use on intraop and postop opioids
–Use of intraop N2O
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
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
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Risk Factors
• Age
• Gender
• Body habitus
• Hx motion sickness
• Hx PONV
• Anxiety
• Concomitant disease
• Operative procedure
• Duration of surgery
Non-anesthetic Factors
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Risk Factors
• Preanesthetic medication
• Gastric distension
• Gastric suctioning
• Anesthetic technique
• Anesthetic agents
Anesthetic Related Factors
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Risk Factors
• Pain
• Dizziness
• Ambulation
• Oral intake
• Opioids
Postoperative Factors
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Postoperative Nausea and Vomiting:Anesthetic Related Factors
• Nitrous oxide
• Volatile anesthetics
• NMB reversal
• Propofol
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Risk FactorsNitrous 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
Omitting nitrous oxide from general anesthesia:
Tramer et al. BJA 1996;76:186-193
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
IS PONV incidence different between 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
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Risk FactorsVolatile 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
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Risk FactorsReversal 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
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Risk Factors Propofol and PONV
Early Late
NauseaVomitingAnyNauseaVomitingAny
Induction 9.3* 13.7* 20.9 50.114.9NA
Maintenance 8* 9.2* 6.2* 5.8* 10.1* 10
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
All Control Event Rates
20% - 60% Control Event Rate
Tramer et al. BJA 1997;78:247-255
Analysis by NNT
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
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
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
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.
Logistic Regression
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
Risk Factors
• Younger age
• Nonsmoking history
• Female
• Hx of motion sickness
• Hx of PONV
• Increased duration of operation
Logistic Regression
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
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
Servizio di Anestesia e Rianimazione Ospedale di Faenza(RA)
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