Transcutaneous
Electrical Stimulation in Treatment of
Postoperative Pain Gary D. VanderArk, MD, Denver, Colorado Kathleen A. McGrath, BS, Denver, Colorado
A novel theory of pain mechanism, the gate-control system, was proposed by Melzack and Wall [I] in 1965. This theory implies that selective stimulation of cutaneous afferent nerve fibers of large diameter inhibits pain [1,2]. Practical methods of employing this concept to relieve pain have been suggested. Stimulation of the dorsal columns of the spinal cord was the first application of this theory, followed by implantation of peripheral nerve stimulators to treat chronic pain syndromes [3]. Transcutaneous electrical stimulation is another approach, first introduced as a screening procedure to determine suitability of patients for surgical placement of a dorsal column stimulator. Because it often produced local analgesia, transcutaneous electrical stimulation was recognized as a potential therapeutic technic [3]. Hymes et al (41 first used transcutaneous electrical stimulation to control acute postoperative pain. They reported a remarkable decrease in postoperative pain, atelectasis, ileus, and duration of intensive care. The controls in their series consisted of patients undergoing operation during a period of time prior to the use of transcutaneous electrical stimulation. In the present study, the effcacy of transcutaneous electrical stimulation in alleviating acute pain was tested in postoperative patients on a prospective, randomized basis. Transcuteneous elecFrom tha Nmrosugary
Sanka. Denver Qsnaral HospIral. and t@ DeLhhmlty of cbbrado Madkd SdKml. chln-
pamnent ofr4eiJmwQsry.
VW. Colorado. This work was wpported by NIH &ant m 2030942. Studbs In Acute Traunn. Rqht re~~O~t8 shod be addrese.ed to Gnry D. VandsrArk. MD, DW sbn of Nmmwqwy. Denver Qmwal Hospital. Demmr, cdaado 80204.
trical stimulation proved to be remarkably tive in relieving pain in these patients.
effec-
Materlal
One hundred patients between the ages of thirteen and eighty-seven who underwent abdominal or thoracic operative procedures during July and August 1974 were studied. All were volunteers. The patients were informed that they may or may not perceive a tingling sensation in the area where the electrodes were in contact with skin and were assured that pain medication as prescribed by their physicians would be available if transcutaneous electrical stimulation (NeuromodTM-TNS Model 3700, Medtronic, Inc., Minneapolis, Minnesota) did not relieve pain. Patients had the option to discontinue tranacutaneous electrical stimulation at any time. Informed consent was obtained after the procedure had been fully explained. Stimulations were scheduled three times a day for twenty minute periods with four hour intervals between periods of stimulation. Stimulation was continued until the patient was discharged, experienced no more pain, or requested that stimulation be discontinued. Patients were assigned randomly to either a control (thirty-nine) or test (sixty-one) group. Patients in the control group received the same instructions as did patients in the test group but were given stimulators that did not contain batteries. Treatment in both groups always began within twenty-four hours after operation. Test subjects had stimulation at a frequency of 100 to 150 cycles per second with an output of 20 to 35
Transcutaneous
milliamperes and a pulse duration of 250 to 400 microseconds. Patients were encouraged to suggest electrode placement for optimal relief. Data indicating the type of operation, postoperative interval of each stimulation, duration of each stimulation, degree of pain experienced during each stimulation as expressed by the patient on a scale of one to ten, duration of relief, pain medication administered during hospitalization, and the presence of atelectasis or ileus were collected for each patient studied. Stimulation was considered a complete success if the patient experienced significant pain relief (greater than 50 per cent) on stimulation and asked for no pain medication during the period of consistent stimulation. Treatment was considered a positive partial success if the patient experienced significant pain relief on stimulation and asked for minimal or no pain medication during the period of consistent stimulation. Stimulation was considered a negative partial success if the patient experienced significant pain relief and asked for the expected amount of pain medication. Treatment was considered a failure if the patient experienced minimal or no relief and asked for the maximal amount of medication or if the patient asked for discontinuation of transcutaneous electrical stimulation. Results Of thirty-nine control patients, thirty-two (83 per cent) experienced no pain relief with mock stimulation. The remaining seven patients (17 per TABLE
I Correlation
Electrical
Stimulation
cent) had some degree of relief with mock stimulation (one, positive partial success; six, negative partial success). All but one of these patients, however, had no objective information to support the claim of some relief. In contrast, of the sixty-one patients in the test group forty-seven (77 per cent) experienced pain relief. Fifteen patients (25 per cent) had complete success and required no analgesic medication, nineteen (31 per cent) had positive partial success, and thirteen (21 per cent) had negative partial success. Treatment was considered a failure in fourteen patients (23 per cent). Maximal relief with transcutaneous electrical stimulation was achieved almost invariably with the first application. In a small minority of patients, stimulation was associated with decreasing efficacy as its novelty diminished. The percentage of patients who had postoperative ileus was 18 per cent in the control group and 16 per cent in the test group. The incidence of atelectasis was 5 per cent in both groups. Age and sex played a significant role in determining patients with significant pain relief in the control group. Although women older than forty years comprised only 23 per cent of the control group, they represented 67 per cent of the patients in the control group considered as having negative partial success. In contrast, age and sex played an insignificant role in the success achieved with transcutaneous electrical stimulation in the test group. Patients less than thirty years of age seemed more skeptical of the stimulation than did
of Results with Type of Operation Total No.
of Type of Operation Control Group Thoracic procedure
Patients
Complete Success
Positive Partial Success
Negative Partial Success
Failure
1
1
I nguinal hernia repair Cholecystectomy Appendectomy Hernia repair Miscellaneous Total
5 7 7 6 13 39
4 6 7 4 10 32
Experimental Group Thoracic procedure Vagotomy and antrectomy lnguinal hernia repair Cholecystectomy Appendectomy Hernia repair Miscellaneous Total
6 2 7 8 10 2 26 61
Volume 130,9eptembar 1975
2 2 3 2 3 0 3 15
1 0 2 3 2 0 11 19
1 0 2 1 4 1 4 13
2 0 0 2 1 1 8 14
339
VanderArk and McGrath
older counterparts. However, after stimulation and ultimate evaluation, this initial skepticism did not significantly affect the results. When patients were classified according to the operation they had undergone (Table I), there was no correlation between the success or failure of transcutaneous electrical stimulation and the specific operative procedure. Comments Inhibitory control of neural input from noxious stimuli by presynaptic mechanisms is the basis of the gate-control hypothesis. In practical terms this ‘means that non-noxious stimuli can interfere with the transmission of pain within the central nervous system. Stimulation of the large myelinated nerve fibers that do not conduct pain will block the transmission of pain prior to perception. Wall and Sweet [2] stimulated large myelinated fibers of peripheral nerves and demonstrated a decreased response to pin prick in the stimulated area. Transcutaneous electrical stimulation also produces local analgesia [5,6]. Our results support the conclusion of Hymes et al [4] that early postoperative pain can be alleviated by this method of treatment. We have attempted to isolate the placebo effect of electronic gadgetry in this present study. Without doubt, relief in some cases had a psychological basis. However, actual stimulation did produce pain relief. A constant observation in our experience was that the patient was able to cough and breath deeply without significant pain during the period of stimulation. With the stimulator in proper position, ambulation often could be carried out with no pain. Our patients received stimulation for only a twenty minute period three times each day. Obviously, this innocuous method of treating pain could be applied much more frequently or even on a continuous basis. In those patients with com-
340
plete relief of pain, total analgesia persisted for an average of only one hour after stimulation for twenty minutes. As previously noted, transcutaneous electrical stimulation in our patients did not produce a significant decrease in postoperative ileus, which may be due to infrequent application in this study. We conclude that transcutaneous electrical stimulation is a significant adjunct to the postoperative alleviation of pain. This method is nonaddictive and does not induce sluggishness as do many medications for pain. Although transcutaneous electrical stimulation obviously is not a panacea as a future analgesic, its role should be assessed critically and not denied. Summary Transcutaneous electrical stimulation as a means of relieving acute pain was evaluated in 100 patients who underwent abdominal or thoracic operative procedures. Transcutaneous electrical stimulation provided pain relief in 77 per cent of test patients as opposed to 17 per cent of control patients. Transcutaneous electrical stimulation is an effective method of treatment that has many advantages over analgesic drugs.
References 1. Melzack R, Wall PD: Pain mechanisms: a new theory. Science 150: 971, 1965. 2. Wall PD, Sweet WH: Temporary abolition of pain in man. Science 155: 106, 196;L. 3. Shealy CN, Maurer D: Transcutaneous nerve stimulation for control of pain. Surg Neural 2: 45, ‘1974. 4. Hymes AC, Raab DE, Yonehiro EG, Nelson GD, Printy AL: Electrical surface stimulation for control of acute post-operative pain and prevention of ileus. Surg Forum 24: 447, 1973. 5. Campbell JN, Taub A: Local analgesia from percutaneous electrical stimulation. Arch Neural 28: 347, 1973. 6. Satran R, Goldstein MN: Pain perception: modification of threshold of intolerance and cortical potentials by cutaneous stimulation. Science 180: 1201, 1973.
The American Journal of 9qery
Electrical Stimulation in Treatment of
Postoperative Pain Gary D. VanderArk, MD, Denver, Colorado Kathleen A. McGrath, BS, Denver, Colorado
A novel theory of pain mechanism, the gate-control system, was proposed by Melzack and Wall [I] in 1965. This theory implies that selective stimulation of cutaneous afferent nerve fibers of large diameter inhibits pain [1,2]. Practical methods of employing this concept to relieve pain have been suggested. Stimulation of the dorsal columns of the spinal cord was the first application of this theory, followed by implantation of peripheral nerve stimulators to treat chronic pain syndromes [3]. Transcutaneous electrical stimulation is another approach, first introduced as a screening procedure to determine suitability of patients for surgical placement of a dorsal column stimulator. Because it often produced local analgesia, transcutaneous electrical stimulation was recognized as a potential therapeutic technic [3]. Hymes et al (41 first used transcutaneous electrical stimulation to control acute postoperative pain. They reported a remarkable decrease in postoperative pain, atelectasis, ileus, and duration of intensive care. The controls in their series consisted of patients undergoing operation during a period of time prior to the use of transcutaneous electrical stimulation. In the present study, the effcacy of transcutaneous electrical stimulation in alleviating acute pain was tested in postoperative patients on a prospective, randomized basis. Transcuteneous elecFrom tha Nmrosugary
Sanka. Denver Qsnaral HospIral. and t@ DeLhhmlty of cbbrado Madkd SdKml. chln-
pamnent ofr4eiJmwQsry.
VW. Colorado. This work was wpported by NIH &ant m 2030942. Studbs In Acute Traunn. Rqht re~~O~t8 shod be addrese.ed to Gnry D. VandsrArk. MD, DW sbn of Nmmwqwy. Denver Qmwal Hospital. Demmr, cdaado 80204.
trical stimulation proved to be remarkably tive in relieving pain in these patients.
effec-
Materlal
One hundred patients between the ages of thirteen and eighty-seven who underwent abdominal or thoracic operative procedures during July and August 1974 were studied. All were volunteers. The patients were informed that they may or may not perceive a tingling sensation in the area where the electrodes were in contact with skin and were assured that pain medication as prescribed by their physicians would be available if transcutaneous electrical stimulation (NeuromodTM-TNS Model 3700, Medtronic, Inc., Minneapolis, Minnesota) did not relieve pain. Patients had the option to discontinue tranacutaneous electrical stimulation at any time. Informed consent was obtained after the procedure had been fully explained. Stimulations were scheduled three times a day for twenty minute periods with four hour intervals between periods of stimulation. Stimulation was continued until the patient was discharged, experienced no more pain, or requested that stimulation be discontinued. Patients were assigned randomly to either a control (thirty-nine) or test (sixty-one) group. Patients in the control group received the same instructions as did patients in the test group but were given stimulators that did not contain batteries. Treatment in both groups always began within twenty-four hours after operation. Test subjects had stimulation at a frequency of 100 to 150 cycles per second with an output of 20 to 35
Transcutaneous
milliamperes and a pulse duration of 250 to 400 microseconds. Patients were encouraged to suggest electrode placement for optimal relief. Data indicating the type of operation, postoperative interval of each stimulation, duration of each stimulation, degree of pain experienced during each stimulation as expressed by the patient on a scale of one to ten, duration of relief, pain medication administered during hospitalization, and the presence of atelectasis or ileus were collected for each patient studied. Stimulation was considered a complete success if the patient experienced significant pain relief (greater than 50 per cent) on stimulation and asked for no pain medication during the period of consistent stimulation. Treatment was considered a positive partial success if the patient experienced significant pain relief on stimulation and asked for minimal or no pain medication during the period of consistent stimulation. Stimulation was considered a negative partial success if the patient experienced significant pain relief and asked for the expected amount of pain medication. Treatment was considered a failure if the patient experienced minimal or no relief and asked for the maximal amount of medication or if the patient asked for discontinuation of transcutaneous electrical stimulation. Results Of thirty-nine control patients, thirty-two (83 per cent) experienced no pain relief with mock stimulation. The remaining seven patients (17 per TABLE
I Correlation
Electrical
Stimulation
cent) had some degree of relief with mock stimulation (one, positive partial success; six, negative partial success). All but one of these patients, however, had no objective information to support the claim of some relief. In contrast, of the sixty-one patients in the test group forty-seven (77 per cent) experienced pain relief. Fifteen patients (25 per cent) had complete success and required no analgesic medication, nineteen (31 per cent) had positive partial success, and thirteen (21 per cent) had negative partial success. Treatment was considered a failure in fourteen patients (23 per cent). Maximal relief with transcutaneous electrical stimulation was achieved almost invariably with the first application. In a small minority of patients, stimulation was associated with decreasing efficacy as its novelty diminished. The percentage of patients who had postoperative ileus was 18 per cent in the control group and 16 per cent in the test group. The incidence of atelectasis was 5 per cent in both groups. Age and sex played a significant role in determining patients with significant pain relief in the control group. Although women older than forty years comprised only 23 per cent of the control group, they represented 67 per cent of the patients in the control group considered as having negative partial success. In contrast, age and sex played an insignificant role in the success achieved with transcutaneous electrical stimulation in the test group. Patients less than thirty years of age seemed more skeptical of the stimulation than did
of Results with Type of Operation Total No.
of Type of Operation Control Group Thoracic procedure
Patients
Complete Success
Positive Partial Success
Negative Partial Success
Failure
1
1
I nguinal hernia repair Cholecystectomy Appendectomy Hernia repair Miscellaneous Total
5 7 7 6 13 39
4 6 7 4 10 32
Experimental Group Thoracic procedure Vagotomy and antrectomy lnguinal hernia repair Cholecystectomy Appendectomy Hernia repair Miscellaneous Total
6 2 7 8 10 2 26 61
Volume 130,9eptembar 1975
2 2 3 2 3 0 3 15
1 0 2 3 2 0 11 19
1 0 2 1 4 1 4 13
2 0 0 2 1 1 8 14
339
VanderArk and McGrath
older counterparts. However, after stimulation and ultimate evaluation, this initial skepticism did not significantly affect the results. When patients were classified according to the operation they had undergone (Table I), there was no correlation between the success or failure of transcutaneous electrical stimulation and the specific operative procedure. Comments Inhibitory control of neural input from noxious stimuli by presynaptic mechanisms is the basis of the gate-control hypothesis. In practical terms this ‘means that non-noxious stimuli can interfere with the transmission of pain within the central nervous system. Stimulation of the large myelinated nerve fibers that do not conduct pain will block the transmission of pain prior to perception. Wall and Sweet [2] stimulated large myelinated fibers of peripheral nerves and demonstrated a decreased response to pin prick in the stimulated area. Transcutaneous electrical stimulation also produces local analgesia [5,6]. Our results support the conclusion of Hymes et al [4] that early postoperative pain can be alleviated by this method of treatment. We have attempted to isolate the placebo effect of electronic gadgetry in this present study. Without doubt, relief in some cases had a psychological basis. However, actual stimulation did produce pain relief. A constant observation in our experience was that the patient was able to cough and breath deeply without significant pain during the period of stimulation. With the stimulator in proper position, ambulation often could be carried out with no pain. Our patients received stimulation for only a twenty minute period three times each day. Obviously, this innocuous method of treating pain could be applied much more frequently or even on a continuous basis. In those patients with com-
340
plete relief of pain, total analgesia persisted for an average of only one hour after stimulation for twenty minutes. As previously noted, transcutaneous electrical stimulation in our patients did not produce a significant decrease in postoperative ileus, which may be due to infrequent application in this study. We conclude that transcutaneous electrical stimulation is a significant adjunct to the postoperative alleviation of pain. This method is nonaddictive and does not induce sluggishness as do many medications for pain. Although transcutaneous electrical stimulation obviously is not a panacea as a future analgesic, its role should be assessed critically and not denied. Summary Transcutaneous electrical stimulation as a means of relieving acute pain was evaluated in 100 patients who underwent abdominal or thoracic operative procedures. Transcutaneous electrical stimulation provided pain relief in 77 per cent of test patients as opposed to 17 per cent of control patients. Transcutaneous electrical stimulation is an effective method of treatment that has many advantages over analgesic drugs.
References 1. Melzack R, Wall PD: Pain mechanisms: a new theory. Science 150: 971, 1965. 2. Wall PD, Sweet WH: Temporary abolition of pain in man. Science 155: 106, 196;L. 3. Shealy CN, Maurer D: Transcutaneous nerve stimulation for control of pain. Surg Neural 2: 45, ‘1974. 4. Hymes AC, Raab DE, Yonehiro EG, Nelson GD, Printy AL: Electrical surface stimulation for control of acute post-operative pain and prevention of ileus. Surg Forum 24: 447, 1973. 5. Campbell JN, Taub A: Local analgesia from percutaneous electrical stimulation. Arch Neural 28: 347, 1973. 6. Satran R, Goldstein MN: Pain perception: modification of threshold of intolerance and cortical potentials by cutaneous stimulation. Science 180: 1201, 1973.
The American Journal of 9qery
