Current Controversies in Adult Outpatient Anesthesia

1. Current Controversies in Adult Outpatient Anesthesia R 3 이 재 우

2. 1970:freestanding ambulatory surgery movement was initiated • the end of 1997 : nearly 70% of all surgeries performed in the US will be done on an ambulatory basis

3. Value-based Anesthesia Care: What Is It? What Does It Mean to Anesthesiologists? • Orkin "value-based care" - essentially the best patient outcome achievable at a reasonable cost

4. The Changing Role of the Anesthesiologist: The Hows and Whys of Preoperative Evaluation

5. Outpatient surgery growth • Anesthesiologists demand skills & choosing a good anesthetics • Anesthesiologist = physician • Pre-op interview & evaluation by a consultant anesthesiologist can be beneficial • Lessening anxiety about op. & ane • Identify medical problems • Initiate appropriate corrective measure • Goal : resolve pre-op problems & minimizing No. of cancellation & Cx.

6. Several approach used to screen pt for ambulatory surgery • Facility visit • Office or clinic visit • Telephone interview with no visit • Review of Health questionnaire • Morning of operation visit • Computer-assisted information gathering

7. Should pt. Age or ASA status influence case selection? • Past : ambulatory surgical facilities arbitrarily with regard to age & ASA • Meridy : could not demonstrate age-related effect • Methodist ambulatory surgicare center : unanticipated admission rate 1.1%(>60yr)- 0.8%(overall) • Natof : ASA3 no higher risk than 1,2 • FASA: little or no relation bteween preexisting disease and the incidence of periop. Cx.

8. Outpatient surgery is no longer restricted to young, healthy patients. • Geriatric and ASA3,4 :acceptable candidates for outpatient surgery if systemic diseases are well controlled.

9. What laboratory tests are really needed? • Most tests :not contribute beneficially to periop Mx. • Lab. Test: possess shortcoming • Fail to uncover pathologic condition • Abnormalities not necessarily improve pt. Care or outcome • Inefficient in screening • Often not appropriately followed • False-positive result

10. $30billion spent were spent on pre-op test & evaluation in U.S. in 1984 ($12-18billion could be saved) • Many facilities now determine : pre-op test are required based on the operative procedure and pt age, preexisting medical disease, medical history

11. The inappropriate patient:who`s OK and who`s not • Few data exist • Anesthesiologist experience ↑ → list of inappropriate patients↓ • At the University of Chicago hospital distinguished several groups of patients may not be appropriate candidates for ambulatory surgery -Unstable pt. Classified as ASA 3 and 4 -malignant hyperpyrexia -MAO inhibitors -complex morbid obesity -acute substance abuse -psychosocial difficulties

12. Discharge criteria for the 21st century : Can short-acting, fast-emergence anesthetics make a difference? Do all patients really need to go to the postanesthesia care unit?

13. RR is no longer the cash cow in a fee-for service system. • Increasingly important for the anesthesiologist to accurately assess the earliest time when pt. Can be safely sent home after surgery. • PACU : shall be available to receive pts after surgery and anesthesia. : all pts. who receive anesthesia shall be admitted to the PACU → current standard

14. Table 1. • Awake,alert,oriented, responsive(or return to baseline • Minimal pain • No active bleeding • Vital signs stable • Minimal nausea • No vomiting • If non-depol NM blockers used, can perform 5-second head tilt • SaO2 94% • On room air

15. Important lessons from short-acting, Fast-emergence study • Pt-bypass first-stage PACU • Surgical center-financial saving • Table 1에 부합되면 second-stage recovery unit로 • Important cost savings can be achieved without compromising patient safety after a bypass paradigm is implemented

16. Inhalational agents for ambulatory surgery into the 21st century : Desflurane and Sevoflurane. Are they safe? Do they really make a difference?

17. Several agents introduction • More rapid recovery, easy titration, fewer side effects • Two new inhalation agents • Sevoflurane & desflurane • Lower blood-gas solubility • Greater control of anesthetic depth and more rapid recovery from GA

18. Desflurane 1.Physical properties -very similar structure of isoflurane -low solubility in blood & body tissues (λb/g : 0.42) ∴ rapid induction & emergence -most characteristic feature : high vapor pressure, ultrashort duration of action, moderate potency

19. 2.Effects on organ systems A.cardiovascular -isoflurane과 유사 -arterial BP ↓ -CO ; relatively uncahanged -HR, CVP, pulmonary artery pressure ↑ B.resporatoy -RR ↑, TV ↓ -pungency, airway irritation ∴ induction시 salivation, breathing- holding, coughing, laryngospasm이 일어날 수 있다.

20. C.cerebral -cerebral blood flow, ICP ↑ -autoregulation ; intact -CMRO2 ↓ D.neuromuscular -response to train-of-four & tetanic peripheral nerve stimulation ↓ E.renal -no evidence fo nephrotoxic effect F.hepatic -no evidence of hepatic inj.

21. 3.Biotransmission & toxicity -minimal metabolism 4.CIx -sever hypvolemia, malignant HTN, intracranial HTN 5.Drug interaction -epinephrine ;safely administered up to 4.5 ㎍/㎏ -nondepolazing blocking agent를 강화

22. sevoflurane 1.Physical properties -halogenated with fluoride -excellent choice for inhalational induciton ; no pungency & rapid FA

23. 2.Effect on organ system A.cardiovascular -mildly depress myocardial contractility -systemic vascular resistance & arterial BP ↓ ;slightly of desflurane , isoflurane B.respiratory -depress respiration -bronchodilator

24. C.cerebral -cerebral blood flow & ICP ↑, CMRO2 ↓ -no seizure activity D.neuromuscular -adequate m.relaxation for intubation of child E.renal -renal blood flow ; slightly ↓ F. hepatic -total hepatic blood flow, O2 delivery는 유지

25. 3.Biotransmssio & toxicity -metabolize similar to enflurane -potentila nephrotoxicity 4.CIx -sever hypovolemia, malignant hyperthermia, intracranial HTN 5.Drug interaction -no sensitization of heart to dysrhythmic effect of epinephrine -nondepolarizing blocking agnet를 강화