CA-1 · intraoperative teaching CA-1 Bootcamp day 4. Authored from cited abstracts; every claim carries a PMID.
THE QUESTIONWhere the evidence disagrees
This topic was selected because an evidence synthesis beats a textbook on it: the trials disagree, or the guidance has moved recently.
THE EVIDENCE
What each source contributes, and how strong it is
Study design first — a cohort and a randomised trial do not carry the same weight.
Design
Year
Journal
What it found
Other
1999
Anesthesiology
The simplified risk score rests on four predictors - female sex, a history of
Other
2004
New England Journal of Medicine
In the 4,123-patient factorial trial ondansetron, dexamethasone and droperidol
Other
2004
New England Journal of Medicine
Because the interventions are similarly effective and independent, prophylaxis
Other
2013
Anesthesia and Analgesia
Pooled across 60 trials, 4 to 5 mg of dexamethasone reduced 24-hour nausea and
Other
2021
New England Journal of Medicine
In 8,725 patients having noncardiac surgery, a single 8 mg dose of dexamethaso
Other
2016
European Journal of Anaesthesiolog
Adding a single antiemetic to an inhalational anaesthetic gave the same overal
6 resolved citations behind this deck; every point above traces to one of them.
IN PRACTICE
What the cohorts and reviews add
6 findings, each on the slide that follows.
Anesthesiology 1999
The simplified risk score rests on four predictors - female sex, a history of
The simplified risk score rests on four predictors - female sex, a history of motion sickness or previous postoperative nausea and vomiting,…
New England Journal of Medicine 2004
In the 4,123-patient factorial trial ondansetron, dexamethasone and droperidol
In the 4,123-patient factorial trial ondansetron, dexamethasone and droperidol each cut the risk of postoperative nausea and vomiting by about 26%,…
New England Journal of Medicine 2004
Because the interventions are similarly effective and independent, prophylaxis
Because the interventions are similarly effective and independent, prophylaxis is rarely warranted in low-risk patients, moderate-risk patients may…
Anesthesia and Analgesia 2013
Pooled across 60 trials, 4 to 5 mg of dexamethasone reduced 24-hour nausea and
Pooled across 60 trials, 4 to 5 mg of dexamethasone reduced 24-hour nausea and vomiting as effectively as 8 to 10 mg, with a number needed to treat…
IN PRACTICE
The simplified risk score rests on four predictors - female sex, a history of
Other · Anesthesiology
The simplified risk score rests on four predictors - female sex, a history of motion sickness or previous postoperative nausea and vomiting, non-smoking status and the use of postoperative opioids - and with none, one, two, three or four of them present the incidence of nausea and vomiting was 10%, 21%, 39%, 61% and 79%.
In the 4,123-patient factorial trial ondansetron, dexamethasone and droperidol
Other · New England Journal of Medicine
In the 4,123-patient factorial trial ondansetron, dexamethasone and droperidol each cut the risk of postoperative nausea and vomiting by about 26%, propofol by 19% and omitting nitrous oxide by 12%, and because the interventions acted independently of one another their relative risks simply multiply.
Apfel et al., New England Journal of Medicine 2004 · PMID 15190136
IN PRACTICE
Because the interventions are similarly effective and independent, prophylaxis
Other · New England Journal of Medicine
Because the interventions are similarly effective and independent, prophylaxis is rarely warranted in low-risk patients, moderate-risk patients may benefit from a single intervention, and multiple interventions should be reserved for high-risk patients - which is the multimodal approach the fourth consensus guidelines recommend for all at-risk surgical patients.
Apfel et al., New England Journal of Medicine 2004 · PMID 15190136
IN PRACTICE
Pooled across 60 trials, 4 to 5 mg of dexamethasone reduced 24-hour nausea and
Other · Anesthesia and Analgesia
Pooled across 60 trials, 4 to 5 mg of dexamethasone reduced 24-hour nausea and vomiting as effectively as 8 to 10 mg, with a number needed to treat of about 3.7 when used alone - so the bigger dose buys you nothing extra for this indication.
De Oliveira et al., Anesthesia and Analgesia 2013 · PMID 23223115
IN PRACTICE
In 8,725 patients having noncardiac surgery, a single 8 mg dose of dexamethaso
Other · New England Journal of Medicine
In 8,725 patients having noncardiac surgery, a single 8 mg dose of dexamethasone was noninferior to placebo for surgical-site infection at 30 days (8.1% versus 9.1%), including in patients with diabetes, so the infection worry that keeps residents from giving it is not supported.
Corcoran et al., New England Journal of Medicine 2021 · PMID 33951362
IN PRACTICE
Adding a single antiemetic to an inhalational anaesthetic gave the same overal
Other · European Journal of Anaesthesiolog
Adding a single antiemetic to an inhalational anaesthetic gave the same overall risk of postoperative nausea and vomiting as substituting propofol total intravenous anaesthesia with no antiemetic at all (relative risk 1.06), so changing the anaesthetic and adding a drug are alternatives rather than a hierarchy.
Schaefer et al., European Journal of Anaesthesiology 2016 · PMID 27454663
IN THE ROOM
What this changes about the next case
Colour is the strength of the evidence behind each step, not the urgency.
1
1
The simplified risk score rests on four predictors - female sex, a history of motion sickness or previous postoperative nausea and vomiting, non-smoking status and the use of postoperative opioids - and with none, one, two, three or four of them present the incidence of nausea and vomiting was 10%, 21%, 39%, 61% and 79%.
2
2
In the 4,123-patient factorial trial ondansetron, dexamethasone and droperidol each cut the risk of postoperative nausea and vomiting by about 26%, propofol by 19% and omitting nitrous oxide by 12%, and because the interventions acted independently of one another their relative risks simply multiply.
3
3
Because the interventions are similarly effective and independent, prophylaxis is rarely warranted in low-risk patients, moderate-risk patients may benefit from a single intervention, and multiple interventions should be reserved for high-risk patients - which is the multimodal approach the fourth consensus guidelines recommend for all at-risk surgical patients.
4
4
Pooled across 60 trials, 4 to 5 mg of dexamethasone reduced 24-hour nausea and vomiting as effectively as 8 to 10 mg, with a number needed to treat of about 3.7 when used alone - so the bigger dose buys you nothing extra for this indication.
5
5
In 8,725 patients having noncardiac surgery, a single 8 mg dose of dexamethasone was noninferior to placebo for surgical-site infection at 30 days (8.1% versus 9.1%), including in patients with diabetes, so the infection worry that keeps residents from giving it is not supported.
The oral-boards stem on the next slide puts these into one scenario.
KEY TAKEAWAYS
What to carry into the next case
The simplified risk score rests on four predictors - female sex, a history of
Anesthesiology 1999
In the 4,123-patient factorial trial ondansetron, dexamethasone and droperidol
New England Journal of Medicine 2004
Because the interventions are similarly effective and independent, prophylaxis
New England Journal of Medicine 2004
Pooled across 60 trials, 4 to 5 mg of dexamethasone reduced 24-hour nausea and
Anesthesia and Analgesia 2013
Count the risk factors, then give one drug from a different class for each one - prophylaxis is stratified by risk, not handed out by reflex.
Questions I'll ask you in the room
Name her risk factors out loud. Which belong to the patient and which belong to your anaesthetic?
You gave her ondansetron and she is retching in recovery. Do you give her more ondansetron?
Why does the dexamethasone go in at induction and the ondansetron towards the end?
What would you change about the anaesthetic itself, rather than adding another drug on top of it?
Oral boards stem
A 28-year-old non-smoking woman is having a laparoscopic cholecystectomy. She volunteers that she vomited for a full day after her wisdom teeth came out, and that she gets carsick. Your attending asks you how many risk factors she carries, roughly what her chance of postoperative nausea and vomiting is, and how many antiemetics she should leave the operating room having received.
The bottom lineCount the risk factors, then give one drug from a different class for each one - prophylaxis is stratified by risk, not handed out by reflex.
Sources
[1] Apfel et al., Anesthesiology 1999 · PMID 10485781 open
[2] Apfel et al., New England Journal of Medicine 2004 · PMID 15190136 open
[3] Gan et al., Anesthesia and Analgesia 2020 · PMID 32467512 open
[4] De Oliveira et al., Anesthesia and Analgesia 2013 · PMID 23223115 open
[5] Corcoran et al., New England Journal of Medicine 2021 · PMID 33951362 open
[6] Schaefer et al., European Journal of Anaesthesiology 2016 · PMID 27454663 open