1. 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

2. 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 mA/cm2
duration = min
recommended concentrations of the ions in the solution used is 1 – 2%

3. 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

4. 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

5. 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

6. 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

7. 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

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