Electrical Stimulation for Wound Healing Professor Tim Watson University of Hertfordshire www.electrotherapy.org Scope of this session Briefly consider the Electrotherapy modalities that can generally influence tissue repair Consider the Bioelectric model and Wound Electrical Stimulation in more detail (c) Tim Watson 2013 1
from Nuccitelli 2003 from Zhao (2009) Current path with full thickness wound in mammalian skin after Jaffe and Vanable 1984 (current represents the movement of positive ions) Wound Potentials + - Polarity of wound polarity is different from normal Wound has POSITIVE polarity compared with intact skin Altered potential gradually returns to normal as healing progresses Different for REPAIR & REGENERATION processes Watson 2008 Kloth, L. C. (2005) Int J Low Extrem Wounds 4(1): 23-44 A : Direct Current B : Pulsed, monophasic C : Pulsed biphasic D : Twin peak monophasic (c) Tim Watson 2013 2
Zhao, M. (2009). Electrical fields in wound healing-an overriding signal that directs cell migration. Semin Cell Dev Biol 20(6): 674-682. Electrical Stimulation for Wound Healing Over 1250 references in database relating to elec stim for wound healing 3 basic approaches Low Intensity Direct Current - LIDC Pulsed LIDC High Voltage Pulsed Galvanic Current (HVPGS) or High Voltage Pulsed Current (HVPC) LIDC A : Direct Current B : Pulsed, monophasic C : Pulsed biphasic D : Twin peak monophasic Most closely linked with endogenous currents Pass low intensity direct current through wound with one electrode in the wound and one on local intact skin? Aims to support the presumed flat skin battery Could fall into microcurrent classification (?) LIDC contd A : Direct Current B : Pulsed, monophasic C : Pulsed biphasic D : Twin peak monophasic Wolcott et al (1969) -ve wound electrode 3/7 then +ve if not infected infection = -ve +3 days 3x daily, 2hrs each @ 0.2-0.8 ma Gault & Gatens (1976) wound -ve electrode initially change at 3/7 or 3/7 post infection no polarity reversal (c) Tim Watson 2013 3
Gault and Gatens (76) 76 patients ; total of 106 ischaemic ulcers of differing aetiology and location. Six patients presented with bilateral ulcers, providing a small control group. For patients with a single ulcer, the mean healing rate was 28.4% per week For the patients with bilateral ulcers, where one was treated with ES and one acted as a control, the mean healing rate of the control ulcers was 14.7% per week, and that of the treated ulcers was 30% per week Carley & Wainapel (1985) 30 hospital inpatients treatment and a control group (random) matched (paired) on the basis of age, diagnosis and wound aetiology, location and size. Wound electrode -ve 3/7 2 hrs 2x daily 5 days / week +ve after 3/7, reversal if plateau (3/7 negative) 300-700µA Carley and Wainapel contd Control group received conventional conservative therapy. LIDC group received 2 hours of LIDC twice a day, 5 days a week in addition to the conventional therapy. Two stimulation sessions were separated by a 2 4 hour rest period when the machine gave no output but remained in situ. One electrode was placed at the wound site, and a dispersive electrode was placed on the skin proximal to the wound. Carley and Wainapel contd Results Patients in the LIDC group showed healing rates that were 1.5 2.5 times faster than those of their paired controls There was no significant difference between the wounds in the two groups at the commencement of the study and the difference did not become apparent until week 3 of the study, after which it became progressively more significant. New Microcurrent Approach New system that incorporates electrical stim module into occlusive wound dressing POSIFECT Fits the logic and the background evidence Limited research to date (c) Tim Watson 2013 4
POSIFECT Papers to date Hampton, S. and F. Collins (2006). "Treating a pressure ulcer with bio-electric stimulation therapy." British Journal of Nursing 15(6): s14-s18 Hampton, S. and L. King (2005). "Healing an intractable wound using bio-electrical stimulation therapy." Br J Nurs 14(15): S30-2 Moody, A. and K. Baines (2007). "Managing a non-healing pilonidal sinus with POSiFECT e- stimulation." British Journal of Community Nursing 12(12 Suppl): S14-S21. Pulsed LIDC Same principle except that pulses of DC are delivered instead of continuous current Argued that more effective than straightforward DC Also possibly less risky to the tissues A : Direct Current B : Pulsed, monophasic C : Pulsed biphasic D : Twin peak monophasic Pulse Parameters As with all pulsed stim, various parameters, though not (currently) possible to identify which are most critical from published research Monophasic / biphasic Symmetrical or Asymmetric Zero Net DC or DC offset Pulse frequency, pulse duration, charge? Currently evaluating options Mulder (1980), Feedar (1991) 1x daily @ 30 min 7x weekly 128Hz Infected wound -ve till infection free plus 3/7 once infection free reduce freq to 64 Hz reverse polarity daily High Voltage Pulsed Current (HVPC) (c) Tim Watson 2013 5
HVPC : Overview High Voltage Not a new modality Widely employed in some countries Almost zero use in others It DOES have a significant evidence base Available on stand alone stimulators and also as an option on multi modal units A variation on other forms od stimulation HVPGS High Voltage Pulsed Galvanic Current High Voltage Pulsed Current Not trying to mimic bioelectric activity Heavyweight type approach (in that pulses are high peak) but AVERAGES to a microcurrent delivery Terminology High Voltage Pulsed Current HVPC is certainly the preferred term Other terms that have been used include : Twin Peak Monophasic High Voltage Pulsed Galvanic Stimulation (HVPGS) And several other variations Also classed by some as falling into the Microcurrent Therapy group A : Direct Current B : Pulsed, monophasic C : Pulsed biphasic D : Twin peak monophasic Multifunction Devices that can deliver HVPC Multifunction device from Gymna Multifunction device from EMS Physio Multifunction device from Chatanooga(DJO) Portable HVPC stimulator from Prizm Medical Portable unit (JACE TriStim) delivering HVPC Portable unit (ChatanoogaHV2) delivering HVPC (c) Tim Watson 2013 6
HVPC as Microcurrent A 'typical' HVPC set of parameters The pulse duration is set at 200µs The interpulse interval is set at 9800µs Therefore 1 cycle will take 10000µs to deliver (which is 10ms - milliseconds). If 1 cycle takes 10ms to deliver, the stimulation frequency will be 100Hz. Although the pulses are high voltage (typically 150-500V), they are of very short duration (microsec) and thus the actual (averaged) current flow through the tissues will be low - in the microcurrent (microamp) range. (illustration from www.nervestudy.com) HVPGS / HVPC Kloth and Feedar (1988) E.g. Akers, Kloth & Feedar (1988) twin pulse monophasic 100-175V (just below muscle contraction) around 100Hz 45 min/day wound +ve wound -ve if plateau Kloth and Feedar (1988) 16 Patients with stage IV decubitus ulcers All had lesions that had been unresponsive to previous treatment. Treatment group (n=9) or sham treatment) group (n=7). The ES consisted of monophasic twin-pulse stimulation at 105 pps. delivered at a voltage just below that required to achieve visible muscle contraction (typically 100 175V). HVPC was given for one 45 minute session a day for 5 days a week. Sham group patients had electrodes placed in the same way, but the machine output was set to zero. Kloth & Feedar (1988) II Electrode set initially for the wound electrode positive, with the negative electrode placed on the skin surface proximally If a healing plateau was reached during the trial, the wound electrode made negative and the treatment continued If a second plateau was reached, the electrode polarity was reversed daily thereafter (c) Tim Watson 2013 7
Kloth & Feedar (1988) III HVPGS / HVPC contd All patients in the treatment group achieved complete healing of their ulcers On average over 7.3 weeks at a mean healing rate of 44.8% per week The control group patients did less well, with an increase in mean wound size of almost 29% between the first and last treatments. Griffin et al (1991) -ve wound electrode 100Hz 200V monophasic twin pulse Griffin et al 1991 High Voltage study... Franek et al (2000) Medical Engineering & Physics 22;647-655 3 groups A (n=33) HVS B (n=32) Topical dressings C (n=14) Control Healing (closure) rate highest in E Stim group Rate of pus clearance also highest in same group Results were statistically significant HVS - double peak monophasic, 100V, 100Hz Another HVPC study... Houghton et al (2003) Physical Therapy 83;17-28 Chronic leg ulcer patients N=27 patients with n=42 ulcers 2 groups (Real HVPC or Sham) 45 min 3x weekly for 4 weeks Mean healing rate Rx group >2x greater than shams (44% vs 16% ) HVPC 100µS, 100Hz, 150V, -ve wound electrode (c) Tim Watson 2013 8
Comparative studies Meta-analysis Stefanovska et al (1993) DC 600µA 2hrs daily AC biphasic, zero net dc, 250µS, 40Hz, 4 sec on, 4 sec off, 15-25µA CONTROL Wound margin electrodes (none in wound) All work but AC results generally better Gardner et al (1999) Effect of electrical stimulation on chronic wound healing: a meta-analysis Wound Rep Reg 7;495-503 15 studies, 24 elec stim and 15 control groups Mean healing rate for elec stim group was 22% and 9% for controls Elec stim most effective on pressure ulcers Difficult to differentiate between different forms of electrical stimulation Kloth, 2005 Kloth, L. C. (2005). "Electrical stimulation for wound healing: a review of evidence from in vitro studies, animal experiments, and clinical trials." Int J Low Extrem Wounds 4(1): 23-44. Watson (2008, 2002, 1999, 1998) Comparison of various wound healing protocols using direct (electrode in wound) stimulation Most regimes appear to be more effective than control or placebo Difficult to establish and clear water between then, though LIDC and Pulsed LIDC probably have the edge Conclusion.... from Young et al 2011 Strong evidence to support a range of different wound electrical stimulation approaches Some good quality trials (not all!!) Difficult to differentiate between approaches Logical biophysical and bioelectric rationale Potential for significant further development (c) Tim Watson 2013 9
from Sebastian et al 2011 : influence of E Stim on wound healing timescale Petrofsky et al (2010) Journal Diabetes 2:41-46 (c) Tim Watson 2013 10