Preoperative lumbar epidural morphine improves postoperative analgesia and ventilatory function after transsternal thymectomy in patients with myasthenia gravis.
OBJECTIVE
To test the hypothesis that preoperative lumbar epidural morphine improves postoperative pain control and ventilatory function after transsternal thymectomy in patients with myasthenia gravis.


METHODS
The study design was randomized, placebo-controlled, and double-blind.


METHODS
After surgery, all patients were admitted to the Neuroscience Critical Care Unit for evaluation and treatment.


METHODS
All patients with myasthenia gravis who presented to the hospital for thymectomy were asked to participate in the study. Twenty patients were randomized to either the placebo or epidural morphine groups.


METHODS
Patients received either epidural morphine (7 mg in 14 mL of sterile saline) or saline (14 mL) before induction of anesthesia. Supplemental iv opioids were administered intraoperatively, with need determined by the anesthesiologist.


METHODS
The main outcome measures were indicators of postoperative pain (e.g., Visual Analog Pain Score, requirement for supplemental opioid administration, respiratory rate) and ventilatory function (e.g., forced vital capacity, negative inspiratory pressure).


RESULTS
Immediately after surgery, the Visual Analog Pain Score in the placebo group was twice as high as the score in the epidural morphine group (placebo 7.0 +/- 1.3; epidural morphine 3.5 +/- 1.2, p less than or equal to .05). During the first eight postoperative hours, the placebo group required more opioids (0.22 +/- 0.03 vs. 0.12 +/- 0.04 mg/kg morphine equivalents, p less than or equal to .06) than the epidural morphine group. Later, both groups received similar amounts of opioids. Patients receiving epidural morphine had better initial recovery of forced vital capacity (at 8 hrs: 55 +/- 6% [epidural morphine] vs. 34 +/- 5% [placebo] of preoperative value, p less than or equal to .05). Respiratory rate was lower for the first 12 postoperative hours in the epidural morphine group, without a difference in PaCO2. There was no difference between groups for the duration of postoperative intubation or ventilation.


CONCLUSIONS
Preoperative lumbar epidural morphine facilitates postoperative analgesia and improves initial postoperative ventilatory performance.
Kirsch
J R
JR
Diringer
M N
MN
Borel
C O
CO
Hanley
D F
DF
Merritt
W T
WT
Bulkley
G B
GB
D000328:Adult; D015360:Analgesia, Epidural / Q000592:standards*; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D007275:Injections, Intravenous; D008297:Male; D008991:Monitoring, Physiologic; D009020:Morphine / Q000008:administration & dosage / Q000627:therapeutic use*; D009157:Myasthenia Gravis / Q000503:physiopathology / Q000601:surgery* / Q000628:therapy; D009294:Narcotics / Q000008:administration & dosage / Q000627:therapeutic use; D010147:Pain Measurement; D010149:Postoperative Pain / Q000175:diagnosis / Q000188:drug therapy* / Q000503:physiopathology; D011229:Preanesthetic Medication / Q000592:standards*; D011446:Prospective Studies; D012119:Respiration; D012121:Respiration, Artificial / Q000592:standards*; D013934:Thymectomy / Q000379:methods*; D013997:Time Factors; D016896:Treatment Outcome; D014797:Vital Capacity
D009294:Narcotics; D009020:Morphine