Effect of the frequency of transcutaneous electrical nerve stimulation on the postoperative opioid analgesic requirement and recovery profile.
BACKGROUND
Transcutaneous electrical nerve stimulation (TENS) at either an acupoint or dermatome corresponding to the surgical incision produces comparable decreases in postoperative opioid requirements and opioid-related side effects. However, the effect of the frequency of the electrical stimulus on the postoperative analgesic response to TENS therapy has not been studied.


METHODS
One hundred women undergoing major gynecological procedures with a standardized general anesthetic technique were enrolled in the study. Patients were randomly assigned to four groups: group I, patient-controlled analgesia (PCA) plus sham TENS (no stimulation); group II, PCA plus low-frequency (2-Hz) TENS; group m, PCA plus high-frequency (100-Hz) TENS; group IV, PCA plus mixed-frequency (2- and 100-Hz) TENS. The PCA device was programmed to deliver 2-3 mg intravenous boluses of morphine with a lockout interval of 10 min. The TENS device was used every 2 h during the day. Standard 100-mm visual analog scales were used to assess pain, sedation, fatigue, and nausea at specific intervals after surgery.


RESULTS
Mixed frequency (2 and 100 Hz) of stimulation decreased morphine requirements by 53% compared with the sham group; low (2-Hz) and high (100-Hz) frequencies produced 32% and 35% decreases, respectively. All three "active" TENS groups reduced the duration of PCA therapy, as well as the incidence of nausea, dizziness, and itching.


CONCLUSIONS
TENS decreased postoperative opioid analgesic requirements and opioid-related side effects when utilized as an adjunct to PCA after lower abdominal surgery. Use of TENS at mixed (2- and 100-Hz) frequencies of stimulation produced a slightly greater opioid-sparing effect than either low (2-Hz) or high (100 Hz) frequencies alone.
Hamza
M A
MA
Department of Anesthesiology and Pain Management, University of Texas Southwestern Medical Center at Dallas, 75235, USA.
White
P F
PF
Ahmed
H E
HE
Ghoname
E A
EA
D000328:Adult; D016058:Analgesia, Patient-Controlled; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D005260:Female; D013509:Gynecologic Surgical Procedures; D006801:Humans; D007044:Hysterectomy; D007889:Leiomyoma / Q000601:surgery; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage / Q000627:therapeutic use*; D010149:Postoperative Pain / Q000188:drug therapy / Q000628:therapy*; D011184:Postoperative Period; D004561:Transcutaneous Electric Nerve Stimulation / Q000379:methods*; D014594:Uterine Neoplasms / Q000601:surgery
D000701:Analgesics, Opioid; D009020:Morphine