THERAPEUTIC DIRECT CURRENT Description refers to a current that passes for more than 1sec continuously in one direction (unidirectional current) also called: constant current or galvanism or galvanic current available units: medium frequency DC type current with pulse type duration of 125 microsec and intervals of 5 microsec giving a duty cycle of 96% Transmission current is transmitted to the site of stimulation through a metal electrode (conductor) that has a wet pad at the end the effect is a chemical change at the electrode-tissue junction (changes of electrolysis) the nature of the change depends on the available electrolytes at this junction in general, acids form at the (+) electrode (anode), while bases form at the negative electrode (cathode) follows Ohm’s law: current in any circuit is directly proportional to the Voltage and inversely to the resistance; thus, the intensity to be used also depends on the resistance encountered resistance here is from the epidermis----- the larger the cross- sectional area the lesser the resistance

Others chemical burns are more likely to occur at the cathode the extent of the chemical change depends on the 1. current intensity per unit area (mA/cm2) or current density 2. duration of time that the current is flowing Iontophoresis The transfer of the ions of drugs into the body through the skin by the use of constant DC A drug in ionic form is applied at the end of electrode which will move to either the cathode or anode depending on whether it is an acid or base; the drug can therefore be introduced into the tissue the amount of drug introduced depends on the current density and duration of treatment thus, dosage is expressed in terms of total current in mA multiplied by time in minutes Current density is limited by the skin resistance Prescription current density = 0.1 to 0.5 mA/cm2, others recommend 0.1 -0.3 mA/cm2 duration = 10 -30 min recommended concentrations of the ions in the solution used is 1 – 2%

Physiological Effects / Therapeutic Uses Direct Current 1.1 Sensory changes mild tingling or prickling sensation which may merge into a mild irritation or itching sensation localized erythema (with prolonged stimulation); more marked in cathode 1.2 Capillary Hyperemia ( not arteriolar dilatation) 1.3 Electronus – depolarization at cathode and hyperpolarization at anode 1.4 relief of pain 1.5 Acceleration of healing 1.6 Tissue destruction – at higher current densities Iontophoresis 2.1 local anesthesia 2.2 relief of idiopathic hyperhydrosis (most common) 2.3 application of drugs such as antibiotic and anti-inflammatory drugs; use of vinca alkaloids has been used to relieve neurogenic pain

Condition Ion used Physiological Effect Dosage Athlete’s foot Cu (+) fungicide 1% copper sulfate solution 10 mA for 15 mins 2x a wk Rhinitis Zinc (+) Coagulation of mucus membrane 2% of zinc sulfate jelly 3mA x 3mins to 8mA to 8mins Decubitus Ulcer bactericidal 1-2% zinc sulfate sol or 2% gel 25-100mA/min wkly for 2-3wks Post-traumatic edema Hyaluronase Breaks down hyaluronic acid 150 units of hyaluronidase in 250ml of a buffer solution of 1.Na acetate 3H2O: 11.42g 2.Glacial acetic acid: 0.923ml 3.Distilled h2O,quantum satis (qs) 1000ml Plantar warts Salicylate (-) Removal and relief of pain 2% aquaeous solution 10mA-mins once a wk for 2-3 treatments Trigger points Novocaine or lidocaine Local anesthesia 1% solution in 60-80% alcohol w/ 1:20,000 adrenalin 20-30mA for 20-30mins up to 3x/day

Condition Ion used Physiological effect dosage Acute RA Cvitrate (-) Prevents allergic response 1% potassium citrate in distilled water 7.5-10mA for 20mis daily to 3x/week Acute and subacute inflammation Dexamethasone (+) with lidocaine HCL Anti-inflamm 4mg dexa Na phospahate in mL sterile water with 2m of 4% lidocaine Hydrochloride 4-5mA for 15-20mins Peripheral circulatory deficit histamine vasodilator 1-10,000 hitsamine diphosphate 3-12 mA for 5-20 mins (60mA-min) 2-3x/week Gout Lithium (+) Competes with Na information of urate, lithium urate is soluble 2% lithium Cl 5 mA for 20mins once a week for 4 weeks

Contraindications for Ion transfer Anesthetic skin in area to be treated Recent scars in treatment site Metal embedded close to skin Acute injury if active bleeding is still present Patients with pace makers

Indications for DC and Iontophoresis Relief of pain Cathodal Galvanism – for chronic pain caused by adhesions, swelling or pressure on nerves - counter irritant effect – on the large sensory fibers and inhibit the pain at spinal level through the presynaptic inhibitory mechanism. Useful for pain caused by ischemia such as in vascular or sympathetic d/o eg., painful amputation stumps, SH syndromes and Sudek’s atrophy. A maximum dosage must be given to achieve desired effect Cathodal Galvanism – relieves Pain by removing the increased concentration of H+ and K+ ions w/c accumulates in ischemia and inflammation - H+ ions are repelled by (+) pole of the anode - low dosage for a maximum length of time is given Adhesions – use of renotin triple response of histamine – inc heat, marked vasodilation, and a wheal Chronic congestion of mucous membrane – transfer of zinc sulfate into congested nasal membranes

Calcium deposits – acetic acid transfer reduces the size of Ca deposit Idiopathic hyperhidrosis - glycopyronium bromide