Ignite Creation Date:
2024-05-05 @ 11:43 AM
Last Modification Date:
2024-10-26 @ 9:12 AM
Study NCT ID:
NCT00114608
Status:
COMPLETED
Last Update Posted:
2008-03-11
First Post:
2005-06-15
Brief Title:
Venous Blood Flow Velocity Electrical Foot Stimulation Compared to Intermittent Pneumatic Compression of the Foot
Sponsor:
University at Buffalo
Organization:
University at Buffalo
Study Overview
Official Title:
Venous Blood Flow Velocity Electrical Foot Stimulation Compared to Intermittent Pneumatic Compression of the Foot
Status:
COMPLETED
Status Verified Date:
2008-03
Last Known Status:
None
Delayed Posting:
No
If Stopped, Why?:
Not Stopped
Has Expanded Access:
False
If Expanded Access, NCT#:
N/A
Has Expanded Access, NCT# Status:
N/A
Acronym:
None
Brief Summary:
Electrical stimulation of the foot can increase blood flow out of the leg This increased blood flow can prevent blood clots from forming in the leg veins
Blood clots in the leg veins can break off and form life-threatening blood clots in the lungs
Intermittent external pneumatic air compression of the foot is already used to increase blood flow in at risk patients
Hypothesis Electrical stimulation of the foot increases blood flow out of the legs to the same degree as intermittent external pneumatic air compression of the foot
Blood clots in the leg veins can break off and form life-threatening blood clots in the lungs
Intermittent external pneumatic air compression of the foot is already used to increase blood flow in at risk patients
Hypothesis Electrical stimulation of the foot increases blood flow out of the legs to the same degree as intermittent external pneumatic air compression of the foot
Detailed Description:
ABSTRACT Background Venous stasis caused by immobility is an important risk factor for venous thromboembolic disease This is especially true for orthopedic patients with multiple trauma and those undergoing other orthopedic procedures A safe and convenient method for reducing venous stasis would be useful for preventing venous thrombosis in patients while in hospital and particularly after discharge during rehabilitation In a prior study we demonstrated that electrical stimulation of the foot was a safe and convenient method for counteracting venous stasis In this study we compare the effects on venous blood flow of intermittent pneumatic compression an established method to electrical stimulation of the foot
Methods 40 healthy volunteers aged 50 - 80 were seated for 4 hours during which they received mild electrical stimulation of the sole of the foot plantar plexus of muscles or intermittent pneumatic compression Popliteal and femoral venous blood flow velocities were measured via Doppler ultrasound Blood flow in the non-stimulated or non-compressed lower extremity served as a simultaneous control Subjects completed a questionnaire regarding their acceptance and tolerance of both treatments
INTRODUCTION Venous thrombosis and pulmonary embolism or venous thromboembolism VTE are important complications of medical and surgical conditions that are associated with prolonged immobilization This is especially true for orthopedic patients with multiple trauma and those undergoing other orthopedic procedures Immobilization is also a major contributor to the increased risk of VTE associated with prolonged air travel
Despite good evidence that prophylaxis is effective there is widespread under utilization of prophylaxis for VTE following major surgical procedures as well as medical conditions that produce weakness or prolonged bed rest There is also good evidence that the risk of VTE continues for weeks after major orthopedic as well as other types of surgery It is now recognized that VTE occurring in the hospital and outside the hospital setting is a single entity and that extended prophylaxis with anticoagulants reduces the risk
Anticoagulant prophylaxis after hospital discharge although indicated in certain high risk groups is inconvenient since the recommended methods LMWH and fondaparinux must be administered by subcutaneous injection and warfarin requires laboratory monitoring
Physical methods that increase blood flow in the leg veins are effective for reducing venous thrombosis in high-risk hospitalized medical and surgical patients These methods include high intensity electrical calf stimulation during surgery graduated compression stockings and intermittent pneumatic compression of the leg or foot Of these only graduated compression stockings which are not very effective can be used after hospital discharge Graduated compression stockings however cannot be adapted to fit all leg shapes may be improperly applied have a tendency to slip down the leg and are found to be uncomfortable by many patients High intensity electrical calf muscle stimulation is painful and can only be used during general anesthesia AC powered external pneumatic compression can only be used while the patient is fully immobilized Thus alternative convenient methods are needed which can be used both in the immobilized and partly mobile patient particularly after hospital discharge
We have attempted to overcome the limitations of currently available physical devices by using mild electrical stimulation of the plantar muscles of the feet Each electrical discharge elicits a foot twitch that causes the intrinsic foot muscles to contract This contraction compresses the plantar plexus of veins thereby increasing venous velocity in the popliteal and femoral veins that is transmitted proximally up the leg veins
Our plantar foot stimulation device is powered by a 9-volt battery and small enough to be inserted into a sock It has the potential to be worn while a patient is immobile standing or walking and therefore is suitable for use both during the initial period of immobilization and throughout convalescence
In an earlier study we reported that mild electrical stimulation of the plantar foot muscles caused an increase in blood flow comparable to that produced by direct calf stimulation
The aim of this new study is to determine if over a 4 hour period mild electrical stimulation of the plantar foot muscles increases venous blood flow velocity to the same degree as intermittent pneumatic compression IPC of the leg in both obese and non-obese subjects
MATERIALS AND METHODS IRB approval and informed consent was obtained from all subjects Forty healthy subjects N 40 between the ages of 50 to 80 participated in the study Half of the subjects N 20 were non-obese with a Body Mass Index BMI 30 The other half of the subjects N 20 were obese with a BMI 30 Exclusion criterion included a prior history of deep vein thrombosis or pulmonary embolism or any trauma or surgery involving any part of the lower extremities
Subjects were studied over 2 sessions At each session subjects received either electrical foot stimulation or intermittent pneumatic compression of one foot The other lower extremity served as a control Subjects received either therapy at one session and the other therapy at a second session at least 48 hours later The right or left leg of each subject was randomly assigned as the same control leg for both studies The type of therapy given at the first session was also randomly assigned
The study otherwise followed the protocol used in our initial study of electrical foot stimulation Subjects were seated for 4 hours in chairs placed at a fixed distance apart They were constantly monitored throughout the study to ensure that they remained seated Subjects were allowed to use a bathroom located several feet away only twice during the 4 hour period During the 4 hour study period subjects were offered a maximum of 16 ounces of fluid and a normal lunch
Electrical foot stimulation was produced by surface electrodes placed on the sole of the foot over the plantar muscle group Electrical stimulation was delivered by the Focus Neuromuscular Stimulation System Empi Inc St Paul MN The crucial stimulus parameters were biphasic symmetrical square wave at 50 pulses per second phase duration of 300 microseconds a starting ramp up time of 2 seconds and a finishing ramp down time of 2 seconds per stimulation cycle and a stimulation cycle of 12 seconds on and 48 seconds off per minute Stimulation was increased to an intensity just sufficient to create a slight visible muscle twitch This level of intensity caused no evident discomfort in any of the subjects in our first study Subjects were continually monitored throughout this study for any indication of discomfort
Intermittent pneumatic compression of the leg consisted of external intermittent pneumatic compression with a knee high device A Tyco Healthcare Kendall Novamedix A-V impulse system Model 6060 Mansfield MA 02048 was used Operating parameters were 130mmHg impulse pressure with a 3 second impulse duration Program Preset 1 for deep vein thrombosis prophylaxis The compression followed the approved standard patient protocol used at our institution detailed in Utilization of Intermittent Pneumatic Compression IPC Stockings for DVT Prophylaxis
Popliteal and femoral venous peak blood flow velocities were measured bilaterally using a Doppler ultrasound device at 0 15 120 and 240 minutes The same ultrasound technician obtained all Doppler studies on all subjects throughout the study All Doppler tracings were be read by the same independent reader in a blinded fashion Immediately following completion of each 4 hour session of electrical foot stimulation or intermittent pneumatic compression subjects were asked to complete a brief questionnaire regarding their acceptance and tolerance of electrical stimulation or intermittent pneumatic compression
STATISTICAL METHODS This study utilized a repeated measures design with two within group factors time to measurement and stimulation stimulation control Stimulation groups electrical foot stimulation and intermittent pneumatic compression IPC were not independent Blood flow measurements at time 120 240 were analyzed with t tests and a mixed model Within the mixed model the group effect is a fixed effect and the subject parameter is a random effect The primary research question was the non-inferiority of the experimental treatment electrical foot stimulation relative to standard treatment intermittent pneumatic compression The non-inferiority index was 50 cmsec this index was formulated prior to analysis The questionnaire results were analyzed using Fishers Exact test P-values that were less than 005 were considered to be statistically significant All analyses were done with SAS 91 Cary NC
Methods 40 healthy volunteers aged 50 - 80 were seated for 4 hours during which they received mild electrical stimulation of the sole of the foot plantar plexus of muscles or intermittent pneumatic compression Popliteal and femoral venous blood flow velocities were measured via Doppler ultrasound Blood flow in the non-stimulated or non-compressed lower extremity served as a simultaneous control Subjects completed a questionnaire regarding their acceptance and tolerance of both treatments
INTRODUCTION Venous thrombosis and pulmonary embolism or venous thromboembolism VTE are important complications of medical and surgical conditions that are associated with prolonged immobilization This is especially true for orthopedic patients with multiple trauma and those undergoing other orthopedic procedures Immobilization is also a major contributor to the increased risk of VTE associated with prolonged air travel
Despite good evidence that prophylaxis is effective there is widespread under utilization of prophylaxis for VTE following major surgical procedures as well as medical conditions that produce weakness or prolonged bed rest There is also good evidence that the risk of VTE continues for weeks after major orthopedic as well as other types of surgery It is now recognized that VTE occurring in the hospital and outside the hospital setting is a single entity and that extended prophylaxis with anticoagulants reduces the risk
Anticoagulant prophylaxis after hospital discharge although indicated in certain high risk groups is inconvenient since the recommended methods LMWH and fondaparinux must be administered by subcutaneous injection and warfarin requires laboratory monitoring
Physical methods that increase blood flow in the leg veins are effective for reducing venous thrombosis in high-risk hospitalized medical and surgical patients These methods include high intensity electrical calf stimulation during surgery graduated compression stockings and intermittent pneumatic compression of the leg or foot Of these only graduated compression stockings which are not very effective can be used after hospital discharge Graduated compression stockings however cannot be adapted to fit all leg shapes may be improperly applied have a tendency to slip down the leg and are found to be uncomfortable by many patients High intensity electrical calf muscle stimulation is painful and can only be used during general anesthesia AC powered external pneumatic compression can only be used while the patient is fully immobilized Thus alternative convenient methods are needed which can be used both in the immobilized and partly mobile patient particularly after hospital discharge
We have attempted to overcome the limitations of currently available physical devices by using mild electrical stimulation of the plantar muscles of the feet Each electrical discharge elicits a foot twitch that causes the intrinsic foot muscles to contract This contraction compresses the plantar plexus of veins thereby increasing venous velocity in the popliteal and femoral veins that is transmitted proximally up the leg veins
Our plantar foot stimulation device is powered by a 9-volt battery and small enough to be inserted into a sock It has the potential to be worn while a patient is immobile standing or walking and therefore is suitable for use both during the initial period of immobilization and throughout convalescence
In an earlier study we reported that mild electrical stimulation of the plantar foot muscles caused an increase in blood flow comparable to that produced by direct calf stimulation
The aim of this new study is to determine if over a 4 hour period mild electrical stimulation of the plantar foot muscles increases venous blood flow velocity to the same degree as intermittent pneumatic compression IPC of the leg in both obese and non-obese subjects
MATERIALS AND METHODS IRB approval and informed consent was obtained from all subjects Forty healthy subjects N 40 between the ages of 50 to 80 participated in the study Half of the subjects N 20 were non-obese with a Body Mass Index BMI 30 The other half of the subjects N 20 were obese with a BMI 30 Exclusion criterion included a prior history of deep vein thrombosis or pulmonary embolism or any trauma or surgery involving any part of the lower extremities
Subjects were studied over 2 sessions At each session subjects received either electrical foot stimulation or intermittent pneumatic compression of one foot The other lower extremity served as a control Subjects received either therapy at one session and the other therapy at a second session at least 48 hours later The right or left leg of each subject was randomly assigned as the same control leg for both studies The type of therapy given at the first session was also randomly assigned
The study otherwise followed the protocol used in our initial study of electrical foot stimulation Subjects were seated for 4 hours in chairs placed at a fixed distance apart They were constantly monitored throughout the study to ensure that they remained seated Subjects were allowed to use a bathroom located several feet away only twice during the 4 hour period During the 4 hour study period subjects were offered a maximum of 16 ounces of fluid and a normal lunch
Electrical foot stimulation was produced by surface electrodes placed on the sole of the foot over the plantar muscle group Electrical stimulation was delivered by the Focus Neuromuscular Stimulation System Empi Inc St Paul MN The crucial stimulus parameters were biphasic symmetrical square wave at 50 pulses per second phase duration of 300 microseconds a starting ramp up time of 2 seconds and a finishing ramp down time of 2 seconds per stimulation cycle and a stimulation cycle of 12 seconds on and 48 seconds off per minute Stimulation was increased to an intensity just sufficient to create a slight visible muscle twitch This level of intensity caused no evident discomfort in any of the subjects in our first study Subjects were continually monitored throughout this study for any indication of discomfort
Intermittent pneumatic compression of the leg consisted of external intermittent pneumatic compression with a knee high device A Tyco Healthcare Kendall Novamedix A-V impulse system Model 6060 Mansfield MA 02048 was used Operating parameters were 130mmHg impulse pressure with a 3 second impulse duration Program Preset 1 for deep vein thrombosis prophylaxis The compression followed the approved standard patient protocol used at our institution detailed in Utilization of Intermittent Pneumatic Compression IPC Stockings for DVT Prophylaxis
Popliteal and femoral venous peak blood flow velocities were measured bilaterally using a Doppler ultrasound device at 0 15 120 and 240 minutes The same ultrasound technician obtained all Doppler studies on all subjects throughout the study All Doppler tracings were be read by the same independent reader in a blinded fashion Immediately following completion of each 4 hour session of electrical foot stimulation or intermittent pneumatic compression subjects were asked to complete a brief questionnaire regarding their acceptance and tolerance of electrical stimulation or intermittent pneumatic compression
STATISTICAL METHODS This study utilized a repeated measures design with two within group factors time to measurement and stimulation stimulation control Stimulation groups electrical foot stimulation and intermittent pneumatic compression IPC were not independent Blood flow measurements at time 120 240 were analyzed with t tests and a mixed model Within the mixed model the group effect is a fixed effect and the subject parameter is a random effect The primary research question was the non-inferiority of the experimental treatment electrical foot stimulation relative to standard treatment intermittent pneumatic compression The non-inferiority index was 50 cmsec this index was formulated prior to analysis The questionnaire results were analyzed using Fishers Exact test P-values that were less than 005 were considered to be statistically significant All analyses were done with SAS 91 Cary NC
Study Oversight
Has Oversight DMC:
None
Is a FDA Regulated Drug?:
None
Is a FDA Regulated Device?:
None
Is an Unapproved Device?:
None
Is a PPSD?:
None
Is a US Export?:
None
Is an FDA AA801 Violation?:
None