Evaluating Transcutaneous Electrical Nerve Stimulation for Postoperative Pain After Video-Assisted Thoracotomy Surgery

Video-Assisted Thoracotomy (VATS) patient's post procedure pain is a significant problem that may delay the recovery of thoracic surgery patients. Without adequate control of pain, the patient's mobilization and ability to participate in bronchial hygiene is compromised increasing the risk for pulmonary complications and inhibiting the body's natural healing ability. When acute post VATS pain is poorly controlled, the incidence of chronic post VATS pain six months or longer after the surgery increases. Post-operative pain is controlled largely through the use of pain medications delivered by a variety of routes including: epidural, intravenous, and when able, oral. Medications used include opioids which have side effects such as nausea, dizziness, drowsiness and constipation that may further delay the patient's recovery and prolong the hospital stay.

Transcutaneous Electrical Nerve Stimulation (TENS) is a method of pain relief that uses cutaneously applied electrodes that deliver electrical signals to peripheral nerves through the intact skin. Treating pain with TENS results in the patient having a reduced perception of pain. The effectiveness of TENS is based on two mechanisms: 1) the gate control theory of pain relief where stimulation of myelinated sensory fibers disrupts neuronal processing in the substantia gelatinosa of the spinal cord, and 2) the stimulation-induced release of endogenous opioids, both in the central nervous system and the general circulation. The present practice for obtaining and applying a TENS unit on a patient for pain relief requires consultation with Physical Therapy who will come and assess the patient and then apply the TENS unit and make recommendations for settings and therapy. This process limits the response to only daytime and often results in a delay in initiation of treatment. After providing education and training it is anticipated that nurses could successfully apply a TENS unit and initiate therapy early in the immediate post operative period. The more timely application of a TENS unit to a post VATS patient could improve pain management outcomes for this population.

Patient's primary area of postoperative pain was determined by nursing personnel. Four electrodes were placed on or around the area of maximum pain by nurses trained in TENS therapy. The TENS unit was turned on, 1 of 5 frequency patterns selected and the impulse turned up until the patient could feel the impulse. The 5 program options available included: #1. Alternate Ramped Burst (ARB) (Rate = 100 pps; Ramp Up Time = 0.5s; On Time = 5s; Off Time = 6s). #2. Simple Modulated Pulse (SMP) (Rate = 125 pps; Cycle Time = 12s; Span Percentage = 40%; Rate stays in the 2-10 pps range for 1/3 of the cycle time (4 seconds) as the rate modulates down to 2 pulses per second (pps) and then back up again. #3. Modulated Amplitude (MA) (Rate = 125 pps; Cycle Time = 1s; Span Percentage = 60%). #4. Simple Modulated Pulse (SMP) (Rate = 125 pps; Cycle Time = 12s; Span Percentage = 40%; Rate stays in the 2-10 pps range for 1/3 of the cycle time (4 seconds) as the rate modulates down to 2 pulses per second (pps) and then back up again). #5 Modulated Amplitude, MA (Rate = 125 pps; Cycle Time = 1s; Span Percentage = 60%). The location of the electrodes, the pattern, and/or the intensity of the TENS unit were adjusted until the patient achieved maximum comfort with the sensation. Five minutes after initiation of TENS therapy and every hour there after - while patient was awake- for a total of 48 hours, the patient was reassessed by nursing staff and TENS settings were adjusted for patient comfort and pain control.