10Anatomy and Physiology of Vomiting The emetic center is an ill-defined area located in the lateral reticular formation of the medulla.It receives input from the chemoreceptor trigger zone, vestibular apparatus, cerebellum, solitary tract nucleus, and higher cortical center.The receptor types include: dopamine, acetylcholine (muscarine), histamine, and serotonin receptors.
12IncidenceThe incidence of PONV ranged from 75~80% during the ether era to approximately 9~43% over the past 40 years.Presently, the overall incidence of PONV for all surgeries and patient populations is estimated to be 25~30%.0.18% of all patients may experience intractable PONV.
13Risk Factors for PONV Patient-related factors Factors related to anesthesiaFactors related to surgery Factors
14Patient-related factors Young ageFemale genderBody weightHistory of PONVHistory of motion sicknessNon-smokingUnderlying disease:metabolic abnormalities (renal failure, uremia, DM…), CNS pathologyPsychological concerns and preoperative anxiety
15Factors related to anesthesia (1) Premedicationopioids (morphine, fentanyl, alfentanil)Anesthetic gasesN2O, halothane, enflurane, isoflurane, desflurane, sevofluraneIntravenous anesthetic agentsetomidate, ketamine
16Factors related to anesthesia (2) Reversal of muscle relaxationPreoperative fastingOtherslong anesthesia, regional anesthesia, postoperative pain, orthostatic hypotension
17Factors related to surgery Strabismus surgeryEar surgeryLaparoscopyOrchiopexyOvum retrievaltonsillectomy
18Previous anesthesia course of this patient Anesthesia method: IVGDifficult intubation -> face maskAnesthesia drugs: propofol, fentanyl 150mg, ketamine 25mgOperation time: am 8:30~ am 8:55Operation method: TUR-BT
19Risk factor of this patient Patient-related factorsnonsmokerFactors related to anesthesiaopioid, ketamineFactors related to surgeryTUR-BT induced electrolyte imbalance
21Guiedlines for prophylactic antiemetic therapy Post operative nausea and vomiting – can it be eliminated?JAMA, March 13, 2002-Vol 287, No. 10Surgical FactorsLaparoscopyLaparotomyPlastic SurgeryMajor Breast SurgeryCraniotomyOtolaryngologic ProceduresStrabismus SurgeryPatient FactorsFemale SexHistory of PONVor Motion SicknessNonsmokerPostoperative Opoid UseMild to Moderate Risk (20~40%)1~2 Factors PresentAny 1 of the Following:Droperidol, DexamethasoneScopolamine,Serotonin AntagonistModerate to High Risk (40~80%)3~4 Factors PresentDroperidol PlusSerotonin AntagonistOrDexamethasone PlusVery High Risk (>80%)4 Factors PresentCombination AntiemeticsPlusTotal IV AnesthesiaWith Propofol
24Lighted Stylet Tracheal Intubation: A Review Anesthesia and analgesiaVolume 90(3)March 2000 pp
25The upper “glow” shows a well defined circle of light just below the hyoid and above the thyroid cartilage in the midline indicating an ideal position for passing the tip of the endotracheal tube between the vocal cords. From this point, the tube should be advanced easily off the stylet and into the trachea where its position will be confirmed by a cone-shaped light above the suprasternal notch (lower “glow).
26The glow demonstrated just as the lighted stylet passes the vocal cords. The initial circle of lightjust above the thyroid cartilage may change to acone of light projecting caudally toward thesuprasternal notch.
27Learning the techniques (1) Lighted stylet tracheal intubation requires practice, but is easily learnedEllis et al:first 25 attempts: 42 seconds2nd 25 attempts: 32 secondsall were successful by the 3rd attempt
28Learning the techniques (2) Fisher and Tunkel :125 children (mean age three years)intubated by anesthesia residents with little or no lighted stylet experienceoverall success rate of 83% and a 76% success rate in infants weighing <10 kgFailures:1. too large a tracheal tube was chosen2. persistent vallecular or esophageal entry
29Prediction of Ease of Intubation Ainsworth and Howells : 200 patients87.5% : successfully intubated on thefirst attempt by using a lightedstylet99%: tracheally intubated within threeattemptsHung et al: 950 patientsno correlation between the time to intubate and any of the airway prediction variables, such as the Mallampati score and the circumference of the neck
30Sympathetic Stimulation During Intubation Laryngoscopy and endotracheal intubation are both intensely stimulating procedures and are associated with varying degrees of sympathetic activity which may be detrimental in patients with coexisting conditions, such as coronary artery disease, elevated intracranial pressure, and asthma.Results from 3 studies:No significant difference bewteen DL and lightwant lighted stylet tracheal intubation, if performed inthe same time as direct laryngoscopy, should notincur greater hemodynamic instability
31Complications and Safety Friedman et al. :- The lightwand group had a significantlylower incidence of sore throat, hoarseness,and dysphagia.- Also, hoarseness and sore throat are lesssevere.Hung et al.’s large comparative trial:A significantly lower incidence of traumatic events and fewer postoperative sore throats in the lighted stylet group
32The Possibility of Heat Damage Nishiyama et al. : a cat model- Temperature at the tip of the Trachlight™ :55° ± 6°C at the time of the first blink103° ± 10°C after 10 blinks (250 seconds in total.)- No macroscopic signs of burn injuries in any of thecats.- Histologically:moderate neutrophil and lymphocyte infiltrationin both the Trachlight™ and the controlspecimens, but no significant differences betweenthe two sides.- These findings suggest that there is little risk ofburn injury from the clinical use of the Trachlight™
33Lighted Stylet Compared with Direct Laryngoscopy
34Indications (1)The difficult airway is possibly the most common indication for the use of the lighted styletReasons:(1) the ability of a lighted stylet to negotiate acuteoropharynx-tracheal angles, particularly insituations in which neck mobility is limited orcontraindicated(2) secretions are not an impedance as they can be indirect or fiberoptic laryngoscopy
35Indications (2)Difficult or impossible direct laryngoscopic intubation in cases of:- Congenital abnormalities of upperairway( Treacher-Collins syndrome,Pierre-Robin syndrome, etc)- Acquired abnormalities of the upperairway( trauma, etc)- Limited mandubular protusion- Short thyromental distance- Short neck- High Mallampati grade- secretions or blood in the oropharynxPatients with fixed dental appliances
36Adult Difficult Airways Hung et al :265 patientsanticipated difficultyunexpected difficult intubations- In all but two patients, tracheal intubation was successful with the Trachlight™, the vast majority on the first attempt.- The failures were patients who were grossly obese.
37Pediatric Difficult Airways Holzman et al. : 31 patients with either known or anticipated difficult endotracheal intubations27/31 : aged 5–17 years.In all but one case, the trachea was intubated by using a lighted stylet in an average of 30–60 seconds
38The Emergency Setting (1) Cervical spine injuries present a particular challenge for airway management, for the airway is likely to be obscured with blood and secretions, and the neck cannot be flexed nor the head extended to aid laryngoscopy. Lighted stylets may be useful under these circumstances, but should not be used if there is suspicion of a fracture of the larynx
39The Emergency Setting (2) Weis claimed a 100% success rate in securing the airway by using lighted stylet intubation in 28 cervical spine casesthe use of lighted stylet intubation:(1) not influenced by blood in the airway(2) allowed administration of cricoid pressure(3) kept the cervical spine in the neutralposition
40Limitations No visualization of pharyngeal and laryngeal structures Suboptimal transillumination in grossly obese patients or in patients with limited neck extension
41DifficultiesDifficulties in controlling the tip of the device in case of accidental partial withdrawal of the styletUnintentional switching off of the light while withdrawing the mental styletDifficulties in withdrawing the mental styletDisturbing effects of the blinking light after 30 seconds from switching on
42Contraindications few absolute contraindications : the presence of an upper airway foreign body, tumor, polyp, retropharyngeal abscess, or other friable tissue along the intubation courseA trauma victim who may have sustained laryngeal injury should have direct visualization rather than blind intubation
43Relative contraindications Some consider a known difficult airway and a planned fiberoptic approach to be a relative contraindication, because a blind lightwand intubation attempt might cause bleeding which could make subsequent fiberoptic visualization of the larynx difficultObesityShort neckLimited neck extensionAwake and/or uncooperative patients
44Complications there have been very few reported complications two reported incidents of instrument disarticulationTrauma to the upper airway after lighted stylet intubation is generally of a minor nature and includes bleeding, sore throat, hoarseness, and dysphagiatwo reported cases of arytenoid cartilage dislocation
45Conclusion (1)Useful in both oral and nasal intubation fort patients with difficult airways.Also useful in emergency sitautions or when direct laryngoscopy and fiberoptic endoscopy is not effectiveCan be used in conjunction with other devices (LMA, intubating LMA, DL)Should be avoided in patients with tumors, infections, trauma or foreign body in the upper airway
46Conclusion (2) a simple technique that is easily learned valuable if tracheal intubation by using direct laryngoscopy is impossible.At worst, the technique is as good as traditional laryngoscopy; at best and in experienced hands, it is quicker, more reliable, and better tolerated by the patient.With the right choice of stylet, it can be used for all sizes of patients and will not significantly increase department costs. It should be available in all anesthetic departments and taught to all trainees.