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FAQs

1- WHAT IS AUTONOMIC NEUROPATHY ?

The autonomic nervous system (ANS) is an extensive neural network whose main role is to regulate the internal environment and body functions by controlling homeostasis, hemodynamics, blood pressure, heart rate, blood glucose levels, sweating and visceral functions (such as digestion, bladder and sexual organs…).
The ANS acts through a balance of stimulation or inhibition of its two components – the sympathetic and parasympathetic nervous systems.
The sympathetic and parasympathetic branches act via neurotransmitter and receptor activation.
Autonomic dysfunction results from an imbalance between the two components and can affect any system of the body.
Autonomic neuropathy is a failure of response from one or both components.

The main causes of autonomic neuropathy are:
Metabolic chronic diseases, high blood glucose, the long duration of diabetes, abnormal fat levels in the blood, and possibly low levels of insulin

Additional causes:

• Neurovascular factors leading to damage of the blood vessels that carry oxygen and nutrients to nerves
• Autoimmune factors that cause inflammation in the nerves
• Mechanical injury to nerves, such as carpal tunnel syndrome or inherited traits that increase susceptibility to nerve disease
• Lifestyle factors, such as smoking or alcohol use
• Vitamin deficiencies, particularly B and D vitamins
• Biemer's Anemia
• Infections, such as Lyme disease, Shingles (varicella-zoster), Epstein-Barr, Hepatitis C and HIV/AIDS
• Kidney, liver or thyroid disorders
• Exposure to toxins
• Repetitive physical stress, possibly from occupational activities.

2-HOW DO LD PRODUCTS ASSESS THE AUTONOMIC NERVOUS SYSTEM ?

LD products analyze the photoplethysmography (PTG) waveform for precise and accurate detection of the beat to beat heart rate (RR-intervals).

The blood pressure lying down and while standing are measured by oscillometry (ANS-1) or by volume plethysmography (TM-FLOW)

The sudomotor function is assessed by a galvanic skin response device either using metal plates following an electrical stimulation of the sweat glands (ANS-1), or disposable cloth electrodes and pressure cuffs placed on the ankles following a double stimulation: 1) metaboreflex and 2) electrical stimulation of the sweat glands (TM-FLOW).
 
The LD products’ assessment of the autonomic nervous system (ANS) follows the diagnostic guidance of the Cardiac Autonomic Neuropathy (CAN) Subcommittee of the Toronto Consensus Panel on Diabetic Neuropathy.

The methods for assessing the autonomic nervous system in a clinical practice include the evaluation of symptoms and  signs, as well as the Heart Rate variability (HRV) analysis, the 
Cardiac autonomic reflex tests (CART’s) which are based on heart rate and blood pressure recordings. In addition, Sudomotor function tests are performed.

The Gold standard assessment of CART’s includes heart rate variability analysis and Ewing tests - such as heart rate responses to deep breathing , standing, Valsalva maneuver and blood pressure response to standing. A tilt table may be suggested for performing  the tests. 

The CART’s score is calculated by using the Jermendy Scoring System  and it allows the result interpretation according to the guidance of the neurological  associations. 

* Medications that significantly affect autonomic testing results:
Chlorpromazine, Thioridazine (Effects: Anticholinergic, antiadrenergic); Tricyclic antidepressants (Effect: Anticholinergic); Bupropion, Mirtazepine, Venlafaxine (Effect: NE reuptake inhibitors); Clonidine (Effect: Alpha-blocking agent); Alpha-blockers, Beta-blockers, Ca-channel blockers (Effects: Alter vasomotor tone and responses); Opiates (Effects: Intoxication: smooth muscle relaxation, histamine release, withdrawal hyperadrenergic state);

Topical capsaicin (Effect: Altered skin vasomotor responses).

3-WHAT IS VASCULAR DYSFUNCTION ?

  
Vascular dysfunction is related  to endothelial dysfunction which is associated with arterial stiffness , microcirculaion disorders and Peripheral Artery Disease (PAD).
Endothelial dysfunction is characterized by a  reduction of the bioavailability of Nitric Oxide (NO) , which upsets the balance between vasoconstriction and vasodilation, and initiates a number of processes that promote hypertension.
In addition, endothelial damage includes increased endothelial permeability, platelet aggregation, pro-inflammatory and pro-coagulatory states, and monocytes migration from the blood into the subendothelial intima and transformation into macrophages, which accumulate lipids to form the lipid core of atherosclerotic plaque and increase arterial stiffness.

Endothelial dysfunction can be caused by several conditions, including diabetes or metabolic syndrome, hypertension, smoking, and physical inactivity 

  Non invasive methods for assessing vascular function comprise:
  • Carotid artery ultrasound 
  • Peripheral artery ultrasound 
  • TCP02 testing
  • Volume plethysmography recordings 
  • Segmental pressures of the upper and lower extremities 
  • Photoplethysmography recordings 


4-HOW DOES LD ASSESS THE VASCULAR FUNCTION ?

TM-FLOW System analyzes the Photoplethysmography (PTG),  and volume plethysmography recordings from segmental pressures of the upper and lower extremities .  
ANS-1 analyzes only the PTG.
Volume Plethysmography is a technique which records the large artery blood flow with pressure cuffs and pump.
Our volume plethysmography analysis provides markers of arterial stiffness ,which are brachial-ankle Pulse Wave Velocity, peripheral Augmentation Index and Central Aortic Systolic Pressure.
Segmental pressures of the upper and lower extremities allow for the calculation of the Ankle brachial Indices in order to diagnose PAD.
PTG is a technique which records the peripheral circulation using infrared light with our oximeter. 
Moreover, LD Technology has a pending patent method for analyzing the spectral domain of the PTG . 
The PTG spectral analysis shows a high specificity and sensitivity to differentiate control groups from diabetic or cardiovascular disease groups
  (i.e. clinical studies - see our clinical studies ).

5-WHICH TARGET POPULATIONS SHOULD BE TESTED BY LD PRODUCTS ?

The target population will be patients who are over 50 year of age, overweight, and/or smokers, and/or diabetic, and/or hypertensive and all patients over 70 year of age.
However, the autonomic nervous system(ANS) testing should be used as a diagnostic tool to evaluate symptoms indicative of vasomotor instability, such as hypotension, orthostatic tachycardia, and hyperhidrosis after more common causes have been excluded by other testing, and the ANS testing is directed at establishing a more accurate or definitive diagnosis or contributing to clinically useful and relevant medical decision making for one of the following indications:
1.To diagnose the presence of autonomic neuropathy in a patient with signs or symptoms suggesting a progressive autonomic neuropathy.
2. To evaluate the severity and distribution of a diagnosed progressive autonomic neuropathy.
3. To differentiate the diagnosis between certain complicated variants of syncope from other causes of loss of consciousness.
4. To evaluate inadequate response to beta blockade in vasodepressor syncope.
5. To evaluate distressing symptoms in a patient with a clinical picture suspicious for distal small fiber neuropathy in order to diagnose the condition.
6. To differentiate the cause of postural tachycardia syndrome.
7. To evaluate change in type, distribution or severity of autonomic deficits in patients with autonomic failure.
8. To evaluate the response to treatment in patients with autonomic failure who demonstrate a change in clinical exam.
9. To diagnose axonal neuropathy or suspected autonomic neuropathy in the symptomatic patient.
10. To evaluate and treat patients with recurrent unexplained syncope to demonstrate autonomic failure, after more common causes have been excluded by other standard testing.

  


6- WHY DOES LD INTEGRATE DIFFERENT TECHNOLOGIES ?

Since the assessment of the autonomic nervous system (ANS) and vascular system require several separate procedures using differing diagnostic tools, which can be expensive, time consuming and difficult to interpret separately, LD products have been developed   by integrating various technologies that allows the physician to have a complete overview of the ANS and vascular function with only one exam. 

Moreover, the integration of these differing technologies reduces the time to perform the different measurements without compromising the accuracy of the results. 

Frequently, physicians face patients who have chronic metabolic disease or other comorbid conditions and symptoms. At times, differentiating vascular from neuropathic disorders can be difficult. 

The symptoms of autonomic neuropathy and vascular disorders can overlap and mimic each other. 


Although the conditions may imitate each other, the causes are often unrelated and treatments are quite different.

By integrating technologies, LD products allows for the early detection of diabetes and its complications.   Our products  help the physician to distinguish between autonomic neuropathy and vascular dysfunction symptoms. Therefore, LD Products’ offer the physician a tool to  better explain the symptom (s) and its cause to the patient, and more treatment options which are easily understood and accepted by the patient.
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