1. Intraoperative Small-Dose Ketamine Enhances Analgesia After Outpatient Knee Arthroscopy Elizabeth Mann, RN, BSN, SRNA Oakland University-Beaumont Hospital Graduate Program of Nurse Anesthesia February 8, 2012

2. Article Menigaux, C., Guignard, B., Fletcher, D., Sessler, D.I., Dupont, X., Chauvin, M. (2001). Intraoperative small-dose ketamine enhances analgesia after outpatient knee arthroscopy. Anesthesia & Analgesia 93, 606-12.

3. Background  Ketamine had been previously been tested in inpatient arthroscopic anterior ligament repair  proving better pain relief and faster return to normal functional activity  Standard treatment for outpatient arthroscopy at the time of study  NSAIDs alone  Combination with intraarticular Bupivacaine and morphine.

4. Hypothesis  A small intraoperative dose of Ketamine will improve postoperative analgesia and facilitate ambulation after arthroscopic meniscectomy and that the benefits will last for several days.

5. Study  Double blinded study  50 patients: 25 in Control Group and 25 in Ketamine Group  Inclusion Criteria:  Patients were all scheduled for elective arthroscopic surgery  ASA status I and II  Between the ages of 18-60

6. Exclusion Criteria  ASA status >II  Surgery performed under regional anesthesia  History of chronic pain  Chronic use of analgesic medications  Drug or alcohol abuse  Psychiatric disorders  Contraindications to NSAIDs

7. Pain Assessment Tools  Verbal rating scale (VRS) and visual analog scale (VAS) while ambulating  VAS: 0-100 mm, 0 is no pain and 100 is worst pain  VRS:  0= no pain  1= light pain  2= moderate pain  3= intense pain  4= severe pain

8. Methods  Consent was obtained  The hospital pharmacist prepared a 10 mL syringe of either isotonic sodium chloride or 0.15 mg/kg Ketamine diluted in isotonic sodium chloride  The group assignments were made with a computer generated random number table  Patients and OR Staff were unaware of their group assignment

9. Methods  Patients were premedicated with 100mg hydroxyzine PO, 1-2 hours before surgery  Induced with Propofol (2mg/kg) followed with Alfentanil (20mcg/kg)  LMA inserted  Mechanically ventilated  GA maintained with Propofol gtt (60-200 mcg/kg/min)  Titrated to maintain HR and MAP within 20% of preoperative vitals  60% N2O in oxygen

10. Methods  Same surgeon  Same technique  Every patient received 20 mL 0.5% Bupivacaine and 5 mg of Morphine injected into knee joint before tourniquet deflation  Propofol gtt was discontinued after trocars were removed from the knee

11. Methods  Transferred to PACU  3 mg IV Morphine (every 5 minutes/PRN) until VAS score was <30 mm or VRS score was <2  Patients received 550 mg Naproxen PO  Patients were discharged home  Instructed to take 550 mg Naproxen twice daily  2 tablets of Di-Antalvic every 6 hours for pain (400 mg Acetaminophen/30 mg dextropropoxyphene)  Resume normal activity as soon as they could

12. Measurements in PACU  Pain scores were evaluated at both rest and mobilization  Recorded every 15 minutes x 1 hour, then at 2, 4, and 6 hours after surgery  Mobilization assessment stopped  VAS score >30 mm  VRS >2  Sedation score > 2 (patient somnolent, responds to tactile stimulation)  HOTN (MAP <60) or Bradycardia (HR <50)

13. Questionnaires POD 1-3  Assessed pain during the night, at their first step, and an over all rating (VAS)  Number of painful events during the day (0-5, 6-10, >10)  Duration of walking during that day (0, <1 hour,1-3 hour, or normal)  Number of doses of Di-Antalvic and any concomitant medication used during the day  Side effects  Whether they experienced bad dreams  Global score of patient satisfaction with pain control

14. Data Analysis  Primary end point: Post-op pain  Secondary end point variables: Analgesic consumption and return to normal walking.  Statistical analysis was performed with NCSS 6.0  Unpaired Student T-tests  Age, weight, length of surgery, amount of Propofol and Alfentanil  Time intervals to SV, LMA removal, arrival to PACU, and discharge home

15. Data Analysis  Mann-Whitney U-test  Analgesic doses, sedation scores, and pain episodes  X2  Frequency of side effects  Results presented as +/- SD or median and 25-75 th percentile ranges  P< 0.05 was considered statistically significant

16. Results  Control group required more Morphine titration in PACU (P<0.05)  Ketamine group had lower VAS scores in PACU while ambulating  Pain scores were lower in the Ketamine group (POD 1-3)  During the night  At their first step  During ambulation  Ketamine group required less additional narcotic (POD1- 3)  There were no reports of N/V, dysphoria, hallucinations, diplopia, cognitive or memory impairments in both groups

17. Strengths/Limitations  Strengths  No patients were excluded  All 50 patients returned the follow up questionnaire  Double Blind Study  Limitations  Small sample size  Difficult to study pain due to subjective measurements

18. Conclusion  This study extended previous studies that evaluated small dose ketamine benefits for inpatient orthopedic procedures.  It provided evidence that a balanced technique with Ketamine could provide better analgesia and improve ambulation without increasing adverse effects.