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P O N V

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  • 1. CASE BASED LEARNING
  • 2. BOOK CASE SCENRIO
    • A 52 year old
    • Anxious man.
    • Presents for revision of a previous tympano-mastoidectomy on an
    • Ambulatory basis.
    • The patient is otherwise in good general health.
    • He has undergone several previous procedures
    • Resulted in post operative nausea and vomiting.
  • 3. QUESTIONS
    • Is the anxious patient a good candidate for surgery under monitored anaesthesia care (MAC)?
    • What general anaesthetic techniques are most likely to minimize postoperative nausea and vomiting (PONV)?
    • Are regional anesthetics less likely to result in PONV in this patient?
    • Why is control of blood loss important during middle ear surgery?
    • Are long-acting neuromuscular blocking agents contraindicated in middle ear surgery?
  • 4.
    • Is the anxious patient a good candidate for surgery under monitored anaesthesia care (MAC)?
  • 5. MAC
    • MAC is a planned procedure during which the patient undergoes local anesthesia together with sedation and analgesia - (ASA).
        • ASA Newsletter 1998;62(12).
    • First choice in 10-30% of all the surgical procedures.
    • The 3 fundamental elements of conscious sedation are:
      • A safe sedation
      • The control of the patient anxiety
      • The pain control.
        • MINERVA ANESTESIOL 2005;71:533-8
  • 6.
    • Able to answer to orders appropriately and to protect airways.
    • Consciousness evaluation
      • Clinical
      • BIS.
    • Discharge - fast.
            • MINERVA ANESTESIOL 2005;71:533-8
  • 7.
    • Retroauricular tympanoplasty and tympanomastoidectomy under local anesthesia with sedation can be well tolerated by the patient, with minimum discomfort.
  • 8. SARMENTO KM JR , TOMITA S .
    • Prospective study of 83 surgeries in 62 patients .
    • 28 type I tympanoplasties, 12 tympanoplasties with ossicular reconstruction, 40 canal wall up mastoidectomies, and 3 revision tympanoplasties.
  • 9.
    • Local infiltration - lidocaine 2% with 1:100 000 epinephrine infiltrated in the retroauricular area and from below the pinna.
    • Sedation was achieved with 50mg of intramuscular promethazine 1h before surgery and intravenous midazolam (0.03mg/kg) at the beginning of surgery.
    • Subsequent doses of midazolam were given to maintain adequate sedation, up to 10mg.
  • 10.
    • The discomfort during surgery was assessed by the patient with a score from 0 to 4.
      • 0=no discomfort and 4=extreme discomfort).
    • Discomfort due to pain had a mean score of 0.83.
    • Noise discomfort (from drilling and manipulation of instruments) had the lowest mean score (0.70),
    • Discomfort from body and neck position had the highest mean score (1.51).
        • Acta Otolaryngol. 2008 Sep 11:1-3
  • 11.
    • What general anaesthetic techniques are most likely to minimize postoperative nausea and vomiting (PONV)?
  • 12. PONV
    • 30% - postoperative nausea and vomiting (PONV).
        • Anesthesiology 1992;77:162– 84.
  • 13. RISK FACTORS FOR PONV
    • Age
    • Gender
    • Obesity
    • Surgical procedure (Ear surgery).
    • History of motion sickness or PONV.
        • Br J Anaesth 1996;76:347–51.
    • Anxiety.
  • 14. ANXIETY
    • Increased anxiety before undergoing anesthesia and surgery is a risk factor for the development of PONV.
        • Anesthesiology 1992;77: 162–84.
  • 15.
    • Operations in or around the ear are considered high risk for PONV – 70%
        • Anesth Analg 1996;82:S37.
        • Anaesthesia 1997;52:544–6.
    • 47% of 162 adults who had middle ear or mastoid surgery experienced PONV.
    • Remained significantly longer in PACU than patients who did not have this complication.
        • Anesth Analg 1996;82:S37
  • 16.
    • Surgery in or around the ear may disturb the vestibular labyrinth, which (along with the chemoreceptor trigger zone) incites the vomiting center.
    • The trigger zone is located in the area postrema (near the trigonum of the vagus nerve), which contains a high concentration of 5-HT3 receptors.
    • The vomiting reflex may be activated when serotonin stimulates the vagal afferents through the 5-HT3 receptors.
        • J. Clin. Anesth., vol. 11, November 1999
  • 17. ANTI-EMETIC CHOICES FOR PONV
    • Promethazine - phenothiazine, has predominantly antidopaminergic effects with moderate antihistaminic and anticholinergic properties.
    • It has been recommended as an antiemetic for patients having ear surgery.
    • Promethazine can cause significant sedation and lethargy.
        • Can Anaesth Soc J 1984;31:407–15.
  • 18.
    • Ondansetron, a 5-HT3 receptor antagonist, decreased PONV after tympanoplasty.
        • Can J Anaesth 1996;43:939–45.
    • Scopolamine.
    • Droperidol.
      • Prolongation of the QT interval.
    • Dexamethasone.
        • Anesth Analg 2000;90:186-94
    • Metochlopramide.
  • 19.
    • A combination of antiemetics that have differing receptor sites may produce better results than either drug alone.
    • The combination of promethazine and ondansetron significantly reduces the incidence of PONV during the first 24 hours after middle ear surgery.
    • The combination reduces significantly the severity of vomiting.
        • Anesth Analg 1996;83:117–22.
  • 20.
    • Propofol infusion reduces PONV as compared to volatile anesthetics.
        • Anesthesiology 1999;91:253-61.
    • Nitrous increases PONV.
        • Anesthesiology 1996;85: 1055-62.
    • TIVA with propofol in place of a volatile anesthetic and nitrous oxide is equivalent to the use of a volatile anesthetic with a prophylactic antiemetic drug.
        • N Engl J Med 2004;350:2441-51.
  • 21.
    • Opioid-sparing techniques, including the use of other analgesics such as nonsteroidal antiinflammatory drugs and regional blocks.
    • Do not use high dose neostigmine (>2.5mg).
    • Hydration with 20 mL/kg of appropriate intravenous fluid preoperatively significantly decreases postoperative nausea on day 1 .
        • Anesth Analg 1995;80:682-6.
  • 22. NON PHARMACOLOGIC TREATMENTS
    • Acupuncture, electroacupuncture, transcutaneous electrical nerve stimulation, acupoint stimulation, and acupressure.
      • Similar to pharmacologic agents in preventing early and late vomiting.
        • Anesth Analg 1999;88:1362-9.
    • Acupressure wristbands may be effective in preventing PONV after short surgical procedures when applied prior to emetic stimulus exposure.
        • Anesth Analg 1997;84:821-5.
  • 23. TYMPANO-MASTOIDECTOMY
    • Tympanoplasty and mastoidectomy.
    • Middle ear surgery.
      • Still operative field,
      • Minimal bleeding.
  • 24. CONDUCT OF GA FOR MIDDLE EAR SURGERY
    • Anesthesia is induced with a hypnotic and short-acting muscle relaxant or by inhalation.
    • Maintainence with a volatile anesthetic.
  • 25.
    • Antiemetics should be given because postoperative vomiting is very common with ear surgery
  • 26.
    • Are regional anesthetics less likely to result in PONV in this patient?
  • 27.
    • Regional anesthesia rather than general anesthesia should be used when possible.
  • 28.
    • Why is control of blood loss important during middle ear surgery?
  • 29. BLOODLESS FIELD
    • Delicate microsurgery of the ear requires adequate hemostasis.
    • Volatile anesthetics and/or vasodilators.
    • MAP – 60-70mm Hg.
    • Elevation of the head of the bed to approximately 15° to decrease venous congestion and local application of epinephrine for vasoconstriction usually improve operating conditions.
  • 30.
    • Are long-acting neuromuscular blocking agents contraindicated in middle ear surgery?