The drugs anesthesiologists give to prevent vomiting after surgery

Main ideas / lessons

• Post-operative nausea and vomiting (PONV) is common and can be worse than surgical pain for some patients. It contributes to delayed discharge and unplanned hospital admission after outpatient surgery.
• PONV has multiple causes, not just anesthesia:
  • Anesthesia-related: certain drugs increase risk.
  • Surgery-related: manipulation of the bowel/abdomen, swallowed blood, inflammation, motion, and pain can trigger nausea pathways.
• Risk varies by patient and procedure. Clinicians use a risk-factor scoring approach to estimate likelihood and guide preventive medication choices.
• Prevention (prophylaxis) is guided by risk level and timing:
  • Higher-risk patients may receive multiple prophylactic drugs from different classes.
  • Timing of each medication is important for effectiveness.
• If prophylaxis fails, “rescue” treatment follows a key rule:
  • Don’t repeat the same drug class; instead, choose a different class.

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Causes of PONV (what the video emphasizes)

1) Anesthesia-related medication contributors

• Opioids (examples given: “delotted,” “fentinyl”; likely fentanyl, but names may be mis-transcribed)
  • Effective for pain, but a reliable cause of nausea
• Volatile anesthetics (examples given: “seofllorine,” “isofllorine”; likely isoflurane/sevoflurane)
  • Used to maintain general anesthesia; these increase PONV risk
• Propofol
  • Presented as having a protective/anti-emetic effect relative to volatile agents
• Newer opioid-free pain option
  • Mentions a drug named susetetrogene (name may be mis-transcribed)
  • FDA-approved in the US; studied as an opioid-free pain-control option, but not yet widespread

2) Surgery-related physiologic triggers

• GI/abdominal manipulation
  • Triggers gut-to-brain nausea centers via nerves
  • Hence higher risk with abdominal surgery and laparoscopic cases
• Swallowed blood
  • Higher risk after ENT (ear, nose, throat) and dental surgeries
• Inflammatory response to tissue trauma
  • A molecular cascade related to surgical injury can induce nausea regardless of anesthesia
• Motion/position changes
  • Being moved or repositioned can activate pathways similar to motion sickness
• Pain itself
  • Post-surgical pain can directly contribute to nausea

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Who is most at risk: risk-factor scoring system (4 factors)

A scoring system estimates PONV risk using four risk factors:

1. Being female
2. History of PONV or motion sickness
3. Planned post-operative opioid use
4. Being a non-smoker (Smoking is described as harmful overall, but appears slightly protective against nausea in this context.)

Risk estimates

• No factors: ~10% chance of PONV
• All four factors: risk approaches 80%

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Surgery/anesthesia factors that increase PONV risk

• Longer duration of anesthesia
• Choice of anesthesia technique
• Type of surgery (higher risk named procedures):
  • Gynecologic surgery
  • Laparoscopic surgery
  • Neurosurgical cases

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Medication selection for prevention (prophylaxis): approach and drug classes

General prophylaxis strategy (based on risk level)

• Low-risk patients: may receive one prophylactic medication, or sometimes none
• Moderate to high-risk patients: typically receive two or three drugs
  • Usually from different medication classes, because combining mechanisms works better than maximizing one drug

Most common prophylactic drugs mentioned

• Ondansetron (trade name noted as Zofran/Zopran)
• Dexamethasone (trade name Decadron)

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Timing rules emphasized (important methodology)

Dexamethasone timing

• Given right after anesthesia starts (at induction)
• Reasons:
  1. Patient comfort/awakening concern
     • If given to awake patients via IV, it can cause brief but uncomfortable burning/tingling (per the video; injection-site discomfort is commonly discussed clinically).
     • Giving it after induction avoids distress.
  2. Timing data
     • Onset is slow, so early dosing helps it take effect by wake-up/emergence.

Ondansetron timing

• Deliberately delayed
• Typically given within ~30 minutes of the end of surgery
• Rationale:
  • Fast onset but shorter duration than dexamethasone
  • If given too early, it may wear off before the patient wakes
  • Timing near emergence improves coverage when patients are vulnerable

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Why clinicians may choose propofol over volatile agents (and the nuance)

Benefits of propofol highlighted

• Lower PONV risk than volatile anesthetics
• Reduced emergence delirium
  • Confused/agitated waking; more common in children
  • Pediatric anesthesiologists are particularly concerned
• Environmental argument
  • Volatile anesthetics described as potent greenhouse gases released via patient exhalation
  • Propofol described as having no direct atmospheric impact, though emissions occur from manufacturing/transportation

Reasons volatile agents may still be chosen (nuanced factors)

• Volatile agents provide certainty of delivery while ventilation is active
• Propofol is IV-delivered, so there’s risk of:
  • IV failure/infiltration
  • If infiltrated under drapes, it can be hard to detect
  • Complexity is described as less with volatile agents

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What to do when prophylaxis fails: rescue methodology

Core rescue principle (explicitly stated)

• If a patient already received a prophylactic anti-nausea medication:
  • Do not give more of the same drug
  • Pick a medication from a different class
  • Reason: receptors are already blocked; “more of the same class” adds no meaningful benefit

Example given

• If ondansetron was given hours earlier, a second dose isn’t expected to help much.
• If a patient already received ondansetron + dexamethasone and is still nauseated in PACU:
  • Clinicians may choose another drug class, with examples mentioned:
    • metoclopramide (subtitle transcription unclear)
    • Another option appearing to be promethazine (subtitle transcription unclear)

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Speakers / sources featured

• Max Feinstein — Anesthesiologist (primary speaker/narrator)
• FDA (Food and Drug Administration) — referenced as approving authority for the newly mentioned opioid-free drug (susetetrogene, per subtitles; name may be mis-transcribed)
• Meta-analyses (multiple) — referenced generally as evidence supporting propofol vs volatile agents (no specific authors/journals named in the subtitles)