Tolerability and Haemodynamic Effects of NMES

Tolerability and Haemodynamic Effects of NMESTolerability and haemodynamic effectuate of NMES in boyish healthy individualsQuinn C1, Cooke J1, Deegan B2, Breen P2, Hannigan A3, Dunne C3, Lyons G2 and Lyons D1.IntroductionDiscomfort has been identified as a limiting factor for the use of go up NMES. Early implementation of NMES devices were so uncomfortable that they could only be used when the patient was under anaesthetic1. Furthermore, miserable quality electrodes combined with monophasic wave material bodys often resulted in skin irritation and burns. Pambianco et al had to discontinue the NMES portion of the effects of heparin, intermittent pneumatic compression and NMES on DVT rates in stroke rehabilitation patients due to annoying and skin blister formtion2. More recently the inclusion of microcontrollers in the design of NMES devices has allowed the implementation of precisely controlled waveforms and saucy algorithms3. These waveforms and algorithms have significantly step-upd the comfort and tolerance of NMES users. More everyplace the use of biphasic pulses, either asymmetric or symmetric has minimised ion redistribution and the subsequent risk of skin irritation and burns.Previous studies have examined patient perceptions of NMES. Alon et al. examined the effect of 4 different electrode sizes on excitatory responses (sensory, motor, pain and pain tolerance) on healthy participants and concluded that NMES comfort increases with increase in electrode size4. They also observed that increasing electrode size decreases the peak voltage corresponding to the excitatory levels. Clarke-Moloney et al measureed the comfort associated with and without NMES on patients with chronic venous insufficiency using a visual analogue dental plate (VAS)5. The authors piece that the comfort categorical rating remained unchanged in all but one patient. This indicated that patients found NMES to be an acceptable therapy which could be significant in future studies involving NMES discourses for venous wound healing.Broderick et al. previously conducted a use up involving healthy participants who underwent a 4 hour comment communications protocol6. Three participants indicated moderate discomfort and 7 only mild discomfort when NMES was commenced. By the peculiarity of the study, 2 participants scores increase to moderate while 2 other participants scores decreased to mild the deviation were unchanged. Kaplan et al. asked each healthy participant who received NMES of the calf or foot muscles to complete a questionnaire regarding the espousal of NMES. Both groups found NMES to be comfortable and strongly felt they would use the NMES device if directed by their doctor7. More recently a study by Corley et al. demonstrated the use of a week-long NMES farm animal melt protocol in conjunction with compression stockings resulted in a high level of compliance and no reported adverse effects8.Our pilot study concluded that NMES may be useful in attenuating lineage pressure drops in older subjects with OH. The asynchronous NMES setting demonstrated the most favourable haemodynamic response. The aims of this study were to assess tolerance and acceptability of both(prenominal) synchronous and asynchronous NMES settings in a young, healthy population during head-up switch testing. A secondary objective was to assess the effect of both settings on haemodynamic parameters in this group.MethodsSubjectsHealthy subjects (n=14) were recruited. decennium were male. The subjects medical history did not reveal any episodes of vasovagal stupefaction, cardiovascular diseases or any other morbidity. no(prenominal) of the subjects used any medication, and all subjects were non-smokers.Ethical ApprovalEthical approval for this study was granted by University Hospital Limerick Research Ethics Committee. All subjects gave written consent to take part in the study. cant over ProtocolSubjects were asked to fast for a maximum of twain hou rs beforehand. Studies were performed in a quiet syncope syncope laboratory room at ambient temperature (21-23 C). The tilt protocol was completed between 9am and 5pm. The study protocol included 3 Head-Up- inclines ( hutch) comprising asynchronous, synchronous settings and control. The order of each encumbrance was randomly assigned using closed(a) envelope randomisation technique.HUT testing was performed using standardised conditions in accordance with the 1996 expert consensus scroll for all patients9. Subjects were required to rest in the supine position for five minutes prior to the assault of a 70 degree positive tilt. This was sustained for three minutes as per European fellowship of Cardiology guidelines10. Haemodynamic changes were recorded using non-invasive beat-to-beat digital artery photoplethysmography Finometer Pro Device (Finapres Medical Systems BV, Amsterdam, The Netherlands www.finapres.com). Continuous cardiac oversee was performed with three lead ECG (fig ure 2). OH was defined as a drop in systolic gilly attender pressure of 20mmHg or in diastolic blood pressure of 10mmHg within three minutes of orthostasis10. The delta (or change) in systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate (HR), mean arterial pressure (MAP), stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR) were recorded in each subject at baseline and at the lowest point (nadir) for each HUT.Electrical stimulation protocolNMES was utilize a custom built, two channel stimulator (Duo-STIM, Bioelectrics Research Cluster, NUI Galway)11. NMES was facilitated through the use of two 5 cm5 cm PALS self-adhesive, hypo-allergenic, skin surface electrodes (Nidd Valley Medical Limited, England) placed over the motor points of the soleus muscles of both legs of consenting patients12 (Figure 3). The stimulator was programmed to provide a pulse width of 350 s, an inter-pulse interval of vitamin C s, a frequency of 36 Hz, a contr action condemnation of 1.2 second, a ramp up time of 500 ms and ramp down time of 300ms. This yielded stimulation amplitudes of 29.18 4.2 V11. The stimulation parameters were selected at a level to achieve maximum blood give ear while ensuring subject comfort. A series of test pulses were applied initially at a very low intensity to establish that the patient was comfortable with the horse sense of electrical stimulation. The stimulus intensity was gradually increased until a noticeable contraction was observed for both legs, as indicated by a visible tightening of the soleus muscle or slight plantar flexion. Stimulation was applied alternatively to each leg with 3 second rest between contractions or synchronously to both legs with 3 second rest period at the onset of each HUT and continued for the three minute study duration.Duplex scanningDuplex Doppler ultrasound was used to monitor the subjects lower limb venous hemodynamic responses using a Siemens Sonoline Sienna ultrasou nd machine with a wideband array probe (Frequency 5 13 MHz). All measurements were performed by a single examiner. Blood spring measurements were taken from the popliteal vein at the lateral aspect of the knee (Fig. 1). Doppler ultrasound with angle bailiwick not exceeding 600 was used and matched to the diameter of the popliteal vein. All measurements were taken from the right leg. Three measurements were taken per parameter and the average of these was used for analyses5, 13. Peak venous velocity was recorded from the popliteal vein. The Doppler machines own software was used to calculate venous volume flow (ml/min) by multiplying the average blood flow velocity by the cross-sectional area of the popliteal vein. Doppler measurements were taken at baseline and on assumption of the upright stance.Figure 1 Placement of ultrasound probe in popliteal stone pitFigure 2 Screen shot of output from ultrasound software demonstrating venous blood flow and peak systolic velocityComfort ev aluation procedureAt 2 time points (just after set-up of the NMES and at the end of the protocol), comfort was assessed by asking subjects to mark their level of comfort using a one hundred mm, non-hatched visual-analogue scale (VAS). A VAS of 30 mm or less was categorised as mild pain, between 31 and 69 mm as moderate pain and scores of 70 mm or greater as severe pain. The minimum clinical significant deflection (MCSD) in VAS was set as an increase in scores between test stages of 12mm14.At the end of the study, the patients were asked to complete a short verbal questionnaire. They were askedTo give a verbal categorical rating of the NMES treatment as very comfortable, comfortable, bearable or unbearable.To clarify preferred stimulation pattern.If they would consider NMES an acceptable form of treatment.Symptom recordingEach subject was asked to mark the degree of symptoms encountered during the HUT using a 100 mm, non-hatched visual-analogue scale (VAS) once the tilt table had r eturned to the horizontal position.Statistical analysisResultsDiscussionConclusionOutcomes for tolerability study1 TolerabilityPain pre and post changeNMES sensationAcceptabilityPreferenceSymptoms2 Haemodynamic parameters for each interventionDelta SBP, DBP, HR, MAP, SV, CO TPRPeak systolic velocityVenous flow3 Associations of presence of initial OHReferences graze NL, Negus D. Prevention of postoperative leg vein thrombosis by electrical muscle stimulation. An evaluation with 125 I-labelled fibrinogen. Br Med J 19703615-618.Pambianco G, Orchard T, Landau P. Deep vein thrombosis prevention in stroke patients during rehabilitation. Arch Phys Med Rehabil 199576324-330.Broderick B, Breen P, OLaighain G, Eelectrical stimulators for surface neural prosthesis. J Autom Control 20081825-33.Alon G, Kantor G, Ho HS. Effects of electrode size on staple excitatory responses and on selected stimulus parameters. J Orthop Sports Phys Ther 19942029-35.Clarke-Moloney M, Lyons GM, Breen P, Burke PE, Grace PA. Haemodynamic study examining the response of venous blood flow to electrical stimulation of the gastrocnemius muscle in patients with chronic venous disease. Eur J Vasc Endovasc Surg 200531300-305.Broderick BJ, OBrien DE, Breen PP, Kearns SR, OLaighin G. A pilot evaluation of a neuromuscular electrical stimulation (NMES) ground methodology for the prevention of venous stasis during bed rest. Med Eng Phys 201032349-355.Kaplan RE, Czyrny JJ, Fung TS, Unsworth JD, Hirsh J. Electrical foot stimulation and implications for the prevention of venous thromboembolic disease. Thromb Haemost 20021035-45.Corley CJ, Breen PP, Birlea S, Serrador JM, Grace PA, OLaighin G. Hemodynamic effects of habituation to a week-long program of neuromuscular electrical stimulation. Med Eng Phys 201234459-456.Benditt DG, Ferguson DW, Grubb BP, et al. Tilt table testing for assessing syncope. American College of Cardiology. J Am Coll Cardiol. 199628 263-275.Brignole M, Alboni P, Benditt DG, et al. Gu idelines on management (diagnosis and treatment) of syncope-update 2004. Executive Summary. Eur summation J. 200425 2054-2072.Breen PP, Corley CJ, OKeeffe DT, Conway R, OLaighin G. A programmable and portable NMES device for foot drop correction and blood flow assist applications. Med Eng Phys 200931400-4008.Baker LL, McNeal DR, Benton LA, Bowman BR, Waters RL. Neuromuscular Electrical Stimulation A concrete Guide. 3rd ed. Downey, California Rancho Llos Amigos Research and Education Institute 1993.Izumi M, Ikeuchi M, Mitani T, Taniguchi S, Tani T. Prevention of venous stasis in the lower limb by transcutaneous electrical nerve stimulation. Eur J Vasc Endovasc Surg 201039642-645.Kelly AM. The minimum clinically significant difference in visual analogue scale pain score does not differ with severity of pain. Emerg Med J 200118205-207.