Frequently Asked Questions – Hospital Applications
The geko™ device, powered by OnPulse™ neuromuscular electro-stimulation technology, is clinically proven to increase blood circulation across a range of in–hospital therapy areas, including the prevention of venous thrombosis (VTE) and the prevention and treatment of oedema.
The geko™ device increases arterial, venous and microcirculatory blood flow. It is CE marked and indicated for the following:
Easy to use, the geko™ device is a battery powered, disposable neuromuscular electrostimulation device designed to increase blood flow in the deep veins of the leg.
The geko™ device gently stimulates the common peroneal nerve activating the calf and foot muscle pumps, resulting in increased blood flow and the reduction of oedema.
Powered by a wrist-watch size battery with software controlled by plus and minus buttons, the self-adhesive geko™ device shapes itself easily and comfortably to the leg.
Green flashing LED lights indicate when the device is switched on and which stimulation level has been set. On the underside of the strap, covered by a water-based conductive hydrogel for secure adhesion, negative and positive electrodes deliver painless neuromuscular electro-stimulation to the common peroneal nerve.
The geko™ device is used in a hospital setting by front-line staff:
The geko™ device is only to be used on the lower limbs. Secure the device to the leg so that the location marker (the line of arrows) is positioned directly over the centre of the fibula head. Correctly fitted, the longer tail should wrap around to the rear of the leg, below and parallel to the crease of the knee. This will place the negative electrode over the common peroneal nerve and will position the ‘plus’ button at the front of the leg and the ‘minus’ button to the rear. The device can also be placed in two alternative fitting locations, just above and just below the crease of the knee aligned to the lateral outer tendon.
The healthcare professional prescribing the device will advise on the protocol for wear depending on your condition. For example, to prevent venous thromboembolism the device should be worn on both legs for 24 hours per day in the acute phase (first 1 to 6 days). For pre-operative swelling reduction in ankle fracture patients requiring surgical fixation, 2 days wear on the affected leg for 24 hours per day will reduce swelling to accelerate time to theatre.
The life time of the geko™ device is controlled by a clock that runs in the software of the device. We know through extensive testing that at the end of the expiry date the battery has sufficient capacity to operate reliably for 30 hours at the maximum setting. As the battery loses capacity its voltage falls and below a certain threshold the device may not function reliably. To maintain VTE prophylaxis the devices needs to be able to operate reliably. A 30 hour life allows for 24 hours continuous operation, with a reserve to give time in which busy staff can change the device and maintain 24 hour VTE prophylaxis.
When activated look for a discernible movement of the muscles in the lower leg and visible outwards and upwards movement of the foot. It is not sufficient to see only a slight movement in the muscles of the lower leg alone. The movement in both the lower leg and foot should be discernible.
No, there is no sensation of pain. There is the feeling of the muscles in the lower leg contracting every second which can take a few moments to adjust to. Thereafter it is common to forget you are wearing the device.
The geko™ device increases venous return in the lower limbs. This reduction in venous pressure reduces peripheral capillary resistance, which enhances arterial blood flow – illustrated by direct measurement of arterial system, increased cardiac ejection and a reduction/abolition of the diastolic flow reversal, the consequences of which allow delivery of more oxygenated blood and nutrients to flow to the entire lower limb.
When we measure the effect of the geko™ on increased blood flow, we use the resting blood flow as the comparator. Tucker et al1 compared the increase in volumetric blood flow between resting and with the geko™ device activated, and found that the geko™ increases the blood flow by 100% in the superficial femoral vein. The superficial femoral vein is the main vein that empties the lower limb and therefore is a good vein in which to measure the overall blood flow in the lower limb.
The measurement of blood flow is made using Doppler ultrasound: this requires the limb being measured to be stationary, therefore it is not possible for a measurement of blood flow during walking to be made.
However, it is known that the effectiveness of the calf muscle pump in pumping blood is approximately proportional to the degree of dorsiflexion. The dorsiflexion given by the geko™ device is equal to 60% to that achieved by walking1.
There is no detrimental effect to sleeping with the devices on. However, if you are finding the devices to be disruptive then discuss this with your healthcare professional who may advise you to either lower the settings or just turn them off completely, if that is consistent with your treatment.
Historically there have been reports of electrical stimulators (such as direct muscle stimulators and TENS machines) interfering with implanted electronic devices. We have had no reports to unsafe interactions between the geko™ and implanted electronic medical devices, such as pacemakers.
The geko™ device complies with stringent international standards relating to interference with other medical devices. However we cannot, at this time be 100% sure that there will not be any interaction as there are so many possible variables to consider, including the type and location of the device, modes of operation, etc. and so we advise caution when using the geko™ on patients with implanted electronic medical devices. In the US, the FDA requires manufacturers of electrical stimulators to warn users not to use such devices on patients with on demand pacemakers.
The geko™ device must be kept clean & dry. Do not bathe or shower whilst wearing the device. Prolonged exposure to water will soften the hydrogel and adhesion may be lost. Immersion may also affect the electronics and prevent proper operation. In the event that the device becomes wet, either by water or bodily fluid, there is no danger to the patient. The adhesive gel is water based and therefore slight dampening of the gel will remove the device from the leg once treatment is complete.
The geko™ is a single-use medical device. This means that it is intended to be used on a single patient as part of a single course of treatment.
The geko™ device is unique in that it delivers neuromuscular electro-stimulation via the common peroneal nerve to activate the calf and foot muscle pumps of the lower leg, as opposed to other electro-stimulation devices that stimulate the muscles directly and can be less well tolerated.
TENS (Transcutaneous Electrical Stimulation of Nerves) uses electrical impulses to reduce pain signals going to the spinal cord and the brain. The mechanism of action is not clear, and there is insufficient good quality clinical data to demonstrate that it is effective.
The geko™ device is a neuromuscular electrical stimulator (NMES). This differs from TENS devices in that it is intended to stimulate motor neurons rather than the nerves responsible for transmitting pain signals. By stimulating the motor neurons in the common peroneal nerve with short electrical pulses, short duration contraction of muscles in the calf and foot occur, which engages the muscle pump of the lower leg and helps return blood to the heart, thereby increasing both arterial and venous blood flow in the lower leg. This stimulation mimics the act of walking.
There are other electrical stimulators that can also stimulate the calf and foot muscle pumps which rely on the direct stimulation of the muscles. These devices generally use a train of pulses (at 30 Hz or higher frequency) to create a contraction that will last for several seconds. This type of device is often referred to a Electrical Muscle Stimulators (EMS). This type of stimulation is uncomfortable because of the strength of contraction that is achieved. These types of stimulators are also used for muscle strengthening.
Essentially TENS devices stimulate the sensory neurons and NMES stimulates the motor neurons. Whilst there may be some overlapping of the effects, stimulation of the motor neurons is required for an effective activation of the calf muscle pumps. Generally TENS devices operate at high frequencies to either affect the pain gate mechanism or the endogenous opioid system (https://www.physio-pedia.com/Transcutaneous_Electrical_Nerve_Stimulation_(TENS) and https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4589923/).
Whilst TENS units can be adapted to stimulate motor neurons, they cannot deliver the painless 1Hz stimulation as the geko™ device does. Typically TENS units operate at ~100Hz (high frequency TENS) or ~10Hz (low frequency TENS).
The geko™ device has a constant current, square wave, asymmetrical, charge balanced pulse. The Constant current refers to the output of the geko™ device which is constant during the duration of the pulse. The voltage of the device will vary according to the patient’s electrical resistance in order to achieve the current output. The stimulation pulse is defined as a square wave. This means that the stimulation current rises rapidly to the required value, which is maintained for the duration of the pulse, followed by a rapid fall to zero. This creates a rectangular or square shape when measured on an oscilloscope, hence the name.
The stimulation pulse is followed by another (return) pulse of lower intensity, but longer duration (asymmetrical) and opposite polarity, to ensure that the overall electrical charge is zero (charge balanced). This prevents electro-chemical changes in the skin.
A microwave oven is a closed sealed unit, tested to a high standard, as such it will not interfere with the geko™ device
Do not use in proximity (i.e. within 1 meter) of short wave / microwave equipment as this may affect the device. We are required by international standards to provide this warning, but practically this will not affect hospital patients. This warning does not apply to microwave ovens, which are shielded against transmitting microwave radiation.
We have a range of published research available for download in the studies section of the website.
NICE Guidance (MTG19) supports use of the geko™ device for people who have a high risk of VTE and for whom pharmacological or other mechanical methods of VTE prevention are impractical or contraindicated.
The savings, as outlined within the NICE guidance, would result from a reduction in the relative risk of DVT and the associated conditions of VTE such as post thrombotic syndrome as well as reduced length of stay.
NICE guidance estimates a saving of £197 per patient when the device is used for a period of 6 days when compared to no VTE prophylaxis and that under these circumstances use of the device will be cost saving until day 14.
In high risk patients when a combination of pharmacological and mechanical VTE prophylaxis is desirable but current mechanical prophylaxis is contraindicated or impractical, the geko™ device in combination with pharmacological prophylaxis will be cost neutral for up to 3 days compared to pharmacological prophylaxis alone.
The adoption of the NICE guidance and the use of the gekoTM device supports the NHS objective of providing VTE prevention to all at risk hospital patients.
There are no contraindications. There are though warnings and precautions. Please refer to the Instructions for Use leaflet inside your geko™ foil pouch or available to download from our IFUs page.
The geko™ device is intended for 24 hour use. It has a battery life nominally up to 30 hours. After that the software switches the device off, permanently.
Please see IFU for further details.
The geko™ device is compliant with the requirements of Directive 2011/65/EU of the European Parliament and of the Council of 8 June 2011 on the restriction of the use of certain hazardous substances in electrical and electronic equipment.
The geko™ device has a shelf life of two years and the expiration date is printed on each pack.
There are no warnings or precautions for using the geko™ device in proximity to surgical metal work. The only problem a user might encounter is if the metal work/surgery has damaged the common peroneal nerve and there is peripheral neuropathy. The device stimulates the common peroneal nerve which causes the muscle contraction and increased blood flow so if your nerve is damaged it might not stimulate the muscle. In this event you would suffer no ill effects. However, seek advice from a healthcare professional to check for neuropathy damage.
No. There are no materials of animal origin used in the geko™ at all.
No. The geko™ device is not manufactured using either latex or phthalates.
Sticking plasters use a different adhesive to that used by the geko™. Skin reactions, such as rashes, are a recognised minor complication associated with electro-stimulation. Some skin reactions with the geko™ device have been reported to us, but we do not yet have enough data to say whether the incidences reported are in line with other electro-stimulation devices. We do warn users of the potential for skin reactions in our Instructions for Use. In some cases skin inflammation or irritation can develop in the contact area, either remove the device or re-attach in the alternative fitting location. Details on the alternative fitting locations are explained in the Instructions for Use.
We are not aware of any instances where the skin reactions represent a serious risk to the health of the patient.
There may be some instances where a minor irritation is acceptable when weighed against the therapeutic benefits of the geko™. This must be discussed and agreed with your healthcare professional.
No. The geko™ device does not contain anything that is known to damage the environment. The geko™ complies with current EU environmental legislation.
We have considered the possible risks associated with using the geko™ device. To ensure its safety we have designed and manufactured the geko™ device in accordance with the International standard for managing the risks of medical devices, ISO 14971. Using this standard as a basis we have designed and manufactured the geko™ devices to be intrinsically safe.
We have conducted extensive biological safety testing, to the International
biocompatibility standard, ISO 10993, and we have data that shows that the hydrogel has
tested negative for cytotoxicity, sensitisation and irritation, and can therefore be considered to hypoallergenic. We have also conducted extensive electrical safety testing. The key International standards are ISO 60601-1, ISO 60601-1-2 and IEC 60601-2-10, the latter being the International standard for electrical safety for powered muscle stimulators.
All of the above data has been reviewed by our Notified Body (SGS United Kingdom Ltd) prior to giving us the CE Marking certification. SGS United Kingdom Ltd employs experts in biological and electrical safety testing to scrutinise the data that we have to demonstrate that the geko™ devices are intrinsically safe and comply with appropriate International safety standards.
We have considered the possible risks associated with using the geko™ device. To ensure its safety we have designed and manufactured the geko™ device in accordance with the International standard for managing the risks of medical devices, ISO 14971. Using this standard as a basis we have designed and manufactured the geko™ devices to be intrinsically safe.
The geko™ device has not specifically been tested when external defibrillators are being used. There is a theoretical risk that the geko™ could stop working because of electrical interference, but the device would not incur any damage and there is no additional risk to the patient. The geko™ device will continue to work during the use of electro-surgery equipment (diathermy), and so this risk may be small.
The geko™ device does not affect the heart rate or blood pressure and therefore the geko™ device can be safely used with these patients
Under ‘precautions’ in the instructions for use we do advise to check the device is functioning correctly every 2 hours, so that there is no significant loss of prophylaxis or treatment should the device be interfered with by the patient.
Yes, the geko™ can be used during surgical procedures. However the geko™ is not sterile, and should not be within the sterile field.
Yes, the geko™ device is safe to use in the presence of operating electro-surgery equipment. Electro-surgery equipment uses electrical currents to cut or cauterize tissues. These currents result in intense magnetic and electrical fields which can interfere with electronic devices, including some neuromuscular stimulators. In the past some neuromuscular stimulators affected by electro-surgery malfunctioned and caused burns to patients, resulting in caution being exercised by the industry and regulators. The geko™ device has been designed and manufactured to be immune to the magnetic and electrical effects generated by electro- surgery equipment, making them safe to use in operating theatres where electro-surgery is being used.
The geko™ will work with a central (spinal or epidural) anaesthesia or a regional block in place, however the geko™ device will not work immediately after a muscle relaxant has been given.
Muscle relaxants are used to facilitate intubation, during this period the geko™ device will not be able to activate the calf muscle pumps, until the muscle relaxant wears off, which is, in most elective surgery, after about 30 minutes.
Most surgery does not need paralysis throughout, and modern ventilators support the patient breathing, so muscle relaxants are not required to suppress breathing. Therefore, the geko™ device would be able to be used most of the time during surgery, and particularly in the critical period when a thrombosis is most likely to form.
General anaesthesia effects the conduction of nerve impulses and will affect the sensitivity of the peroneal nerve to stimulation by the geko™ device. It is very likely that the stimulation level will be affected by anaesthesia, and in some cases may not achieve stimulation. If stimulation is visible in the patient (i.e. by a twitch of the foot) then there is an increase in blood flow.
The geko™ device is not contraindicated for use following Coronary artery bypass grafting (CABG) using the saphenous vein. When using the geko™ device the patient should be cardiovascular stable, and the donor site should be appropriately ligated/healed.
Some neuromuscular blocking drugs can interfere with the geko™ device. This may be an issue during intra-operatively, depending on the anesthetic regime employed. There may also be a period of ‘wash-out’ post-surgically, when the geko™ device may not fully stimulate the calf-muscles.
Anaesthetic agents: general anaesthesia and muscle relaxants may affect the response
The use of the geko™ device has been the subject of numerous studies (over 60 publications and counting) and there have been no reports of any long-term problems with the stimulation level.
The amount of electrical charge required by the geko™ device to achieve stimulation of the common peroneal nerve is much less than other electrical stimulators because of the unique way in which the geko™ device works. The electrical charge is ‘balanced’, that is there is zero net charge delivered to the patient, this is achieved by having a series of small pulses following the stimulation pulse of opposite polarity which balances the charge in the stimulation pulse without stimulating the nerve further. This prevents electrochemical changes in the skin occurring.
If ‘over stimulation’ refers to the strength of the contraction, there is a natural limit to the strength of the muscle contraction that geko™ device can achieve. The stimulation level is controlled by the pulse width (that is the length of time that the stimulation pulse lasts for). The maximum 560 micro-second pulse width will only cause a single short contraction of the calf muscles controlled by the common peroneal nerve. Longer contractions require repeated stimulation pulses. Other electrical stimulators use trains of pulses at a frequency of 30 Hz or more for several seconds. These cause tetanic contractions in the muscles. These types of stimulators can cause muscle fatigue and can be used for muscle toning. They are however uncomfortable to use.
There is no long-term effect on the nerve: the geko™ device has been used over periods of several weeks to treat chronic conditions and no issues of overstimulation have been reported in subsequent publications.
The safety of the geko™ devices has not been tested on children.
The Instruction for Use states that the geko™ device must be kept out of reach from children and pets. The safety and effectiveness of the geko™ has not been tested on people under the age of 18. The geko™ device uses NMES to emulate the increase in blood flow normally achieved by walking (up to 60%), so it is unlikely to cause problems in normal adolescents. Therefore, it is a Clinician’s decision, exercised with caution, to prescribe the use of the geko™ device to a child between the ages of 13-18 years old, however we advise that it is used under supervision to prevent mis-use.
The geko™ device has been shown to be unaffected by, and safe to use in the presence of high frequency electro-surgical equipment. Please note that some older stock may still have a warning concerning the use of geko™ device in the presence of high frequency surgical equipment. NB: some people refer to this type of equipment as ‘diathermy’.
The Instruction for Use contains the following warning: ‘The geko™ device is not intended for use in an oxygen rich environment’ because Firstkind has not verified whether the device meets the requirements for that intended purpose.
An ‘Oxygen rich environment’ implies environments where the oxygen concentration is:
These conditions may typically occur in hospital oxygen tents, but not necessarily where supplemental oxygen is dispensed topically (e.g. in operating theatres). For reference, the ‘normal’ concentration of oxygen at sea level is 21%, the pressure at sea level is around 100kPa, and metrological ‘high pressure’ is about 105kPa.
In areas of lower oxygen levels, e.g. oxygen tents mimicking high altitude, the geko™ device is suitable for use. Please check with the manufacturer if you have any concerns about its use in this type of environment.
Do not apply stimulation over open wounds or rashes, or over swollen, red, infected, or inflamed areas or skin eruptions. This may include conditions such as phlebitis, thrombophlebitis or varicose veins where the skin is inflamed or compromised.
Arterial line placement is a common procedure in various critical care settings. Intra-arterial blood pressure (BP) measurement is more accurate than measurement of BP by non-invasive means, especially in the critically ill.
Intra-arterial BP management permits the rapid recognition of BP changes that is vital for patients on continuous infusions of vasoactive drugs.
Arterial cannulation also allows repeated arterial blood gas samples to be drawn without injury to the patient.
Overall, arterial line placement is considered a safe procedure, with a rate of major complications that is below 1%. It is not entirely without risks, however, and it requires appropriate knowledge of the anatomy and procedural skills. Arterial lines can be placed in multiple arteries, including the radial, ulnar, brachial, axillary, posterior tibial, femoral, and dorsalis pedis arteries.
The arterial line would not interfere with the geko™ itself.
When the arterial line is placed in the dorsalis pedis artery it would need to be very secure since the geko™ causes dorsiflexion movement of the foot at 1 Hz. Clinicians must regularly inspect the area for signs of ischemia, and remove the catheter at the first signs of circulatory compromise or clot formation; do not flush the catheter in an attempt to remove clots.
The geko™ stimulation pulse will not interfere with the transducer measuring the BP as it will be electrically isolated.
There is a very small chance that the geko™ device may have turned off during defibrillation. Check that the geko™ is still switched on and causing dorsiflexion (upwards and outwards movement of the foot) following defibrillation. If the geko™ device has switched off, restart the device and adjust the setting to achieve dorsiflexion.
The geko™ device has been tested for electromagnetic compatibility (this is the level of electromagnetic emissions produced by the geko™) and is it unlikely to affect other medical devices.
The geko™ device has also been tested to ensure that sources of electromagnetic interference (e.g. other devices, mobile phones etc.) do not interfere with the operation of the device.
We do not anticipate any issues with the geko™ device interfering with (or being interfered by) other medical devices, such as glucose monitors.
There are two main types of compartment syndrome: Acute and Chronic.
The geko™ device should not be used on patients suspected of or have been diagnosed with acute compartment syndrome after a traumatic injury.
Firstkind Ltd does not have data supporting use of geko™ device in individuals with exercise induced chronic compartment syndrome.
The device launched in April 2018 is a new variant of the T-2 geko™ device designed for in-hospital clinical applications. The new device provides an increased range of stimulation levels at both the low and high end of the settings spectrum, and the addition of a third electrode for improved comfort. Please refer to the product specification page here.
Firstkind Ltd is a wholly owned subsidiary of Sky Medical Technology Ltd, a privately held UK company based in High Wycombe and Daresbury. Firstkind manufacture medical devices utilising OnPulse™, Sky Medical’s proprietary neuromuscular electro-stimulation technology designed to enhance the body’s own circulation to increase lower limb blood circulation.
