Iontophorosis

*Introduction:-

~the term iontophoresis is simply defined as ion transfer(ionto=ion),(phoresis=transfer)

Iontophorosis


~introduction of ions into the body using direct electrical current.

~it is a specialzed tecnique of electrical stimulation that uses electrical polarity of continuos direct current to ionize medicines placed beneath surface electrodes and transfers them into the body through the skin.

*Basic principle:-

~current required
~ionic polarity
~low-level amplitude
~electrode size

*Current required:-

~in order to ‘drive’ the ions into the tissues ,a direct (galvanic) current needs to be employed.
~a monophasic pulsed application can also be used.
~constant current is preferable to constant volatage thus,the magnitude of the applied current will not exceed the prest level in terms of skin resistance.

*Ionic Polarity:-

~the basis of successfull ion transfer lies in physcis principle like poles repel and unlike poles attract.
~ions with a polarity which is the same as that of the stimulating electrode are repelled into the skin.
~the electrode under which the ionic soltion is placed is called the active electrode.
~the other electrode,which is the complete the circuit is most commonly called the DISPERSIVE,INDIFFERENT,INACTIVE or RETURN electrode.

*Low -level Amplitude:-

~low level amplitude is more effective.
~the treatment is usually applied with currents upto 5 mA.
~with low ionic concentrations -up to 5%.
~treatment times are typically in the 10-30 minute range.

*Electrode size:-

~the negative electrode should be made larger than the positive electrode(usually twice).
~enlarging the negative electrode size lowers the current density on the negative pad,leading to reduction of irritation.

*Physiologial changes:-

~ion penetration
~acid/alkaline reactions
~hyperemia
~dissociation

*Ionic penetration:-

~penetration does not exceed 1mm.
~subsequent deeper absorption through the capillary circulation.
~the bulk of deposited ion at the active electrode are stored,to be depleted by the sweep of circulating blood.

*Acid/alkaline reaction:-

~will get ACID accumulation under the POSITIVE (anode)electrode (weak HCL).
~this is because negatively charged chloride ions (CL- from NACL)is attracted towards the anode.
~this is considered sclerotic,which tends to harden tissues,serving as an analgesic agent due to local release of oxygen.

*will get alkaline accumulation under the negative NEGATIVE(cathode)electrode.
~because the positively charged sodium ions (NA + from NACL)will move towards the cathode.
~the NA+ ions react with water to form sodium hydroxide(NAOH).
~considered sclerolytic,which is a softening agent due to the hydrogen release,serving in the management of scars and burns.

*Hyperemia:-
~both the positive and negative electrodes produce hyperemia and heat due to the resulting vasodilatation.
~the cathodal hyperemia is generally more pronounced and takes more time to disappear than that of the anode.
~generally,hyperemia under both electrodes,does not last than more hour.

*Disscoation:-

~ionizable substances dissociate in solution releasing ions.
~with the passage of direct current into the solution migrate toward the other pole.
~gets absorbed through the capillary circulation.
~this is an concept of ion transfer.

*Complications:-

~chemical burns
~heat burns
~sensitivities and allergic reactions to ions.

*Chemical burns:-

~this is due to excessive formation of strong sodium hydroxide at the cathode.
~the skin becomes pinkish initially,to be grayish and oozing wound few hours later.
~this burns take long time to heel.
~should be treated with antibiotics and sterile dressings.
~burns under the anode are rare,
~appears as a hardened red area similar to a scab.

*Heat burns:-

~occurs due to excessive heat bulidup in areas with high resistance.
~most of this burns occur when,
~the electrode are not moist enough
~they are not fitting well or,
~not in good contact with the skin.
~should be treated with the antibiotics and sterile dressings.

*Allergic reactions to ions:-

~if the patient is allergic to seafood,”iodine”should not be used.
~patients with an active peptic ulcer or gastritis,react poorly to ‘hydrocortisone’.
~patients,who have prolems with aspirin,reacts poorly with salisylates.
~patients sensative to metals may react to copper,zinc or magnesium.

*Indications:-

~local anesthesia
~inflammatory conditions
~relief of pain
~skin conditions
~tension headache
~inhibition of spasticity

*Contraindications:-

~open wounds or burns
~patients with cardiac pacemakers
~allergy to medication
~loss of sensation
~greasy or dirty skin
~sole of foot(hard for the ions to pass inside)

*Precautions:-

~dont use two chemicals under the same electrode,even if they are from the same polarity.
~dont administer ions with opposite polarities during the same treatment session.

*Current Density:-

~the current density measured in mA/cm2.
~if the current density reaches too high a level,tissue damage,especially skin burn,may ensue.
~it is suggested that a maximum safe current density of,
~o.5 mA/cm2 is applicable at the negative(cathode) and
~1.0 mA/cm2 at the positive(anodal)electrode.

*Current Intensity:-

~calculated as:-
~maximum current(mA)=maximum safe current density(mA/cm2) X electrode area(cm2)
~recommended current intensity is 3 to 5 mA.

*treatment time:-

~treatment time:-ranges between 10-20 min.
~patient should be comfortable with no reported or visible signs of pain or burning.
~check skin every 3-5 minutes for signs of skin irritation.

*Formula for iontophorosis:-

~I x T x ECE =grams of substance introduced
~where:-
~I-(intensity)=measured in amperes.
~T(time)=measured in hours.
~ECE(electro chemical equivalent)represents standardized figures for ionic transfer with known currents and time factors.
~as the determination of the ECE for many complex substances is very difficult ,fewer milligrams of these complex substances will penetrate the skin.

*Electrodes:-
~Traditional electrodes
~Commercial electrodes

*Traditional electrodes:-

~older electrodes made of tin,copper,lead,aluminum,or platinum backed by rubber.
~completely covered by sponge,towel,gauze which contacts skin.
~absorbent material is soaked with ionized solution.(medication)
~if medicated ointment is used,it should be rubberd into the skin and covered by some absorbent material.

*Commercial electrodes:-

~sold with most iontophoresis systems.
~electrodes have a small chamber covered by a semipermeable membrane into which ionized solution may be injected.
~the electrodes self adheres to the skin.

*Electrode preparation:-

~attach self-adhering active electrode to skin.
~ inject ionized solution into the chamber.
~attach self-adhering inactive to the skin and attach lead wires from the generator.

*Application:-

~the skin should be abrasion/cut free and
~the area carefully washed (soap and water is fine)


~dry electrodes are inappropriate and should not be used.
~if pregelled electrodes are being used,ensure that a good even contact is achieved.


~adequate fixation of the electrode and pad to the skin needs to be carefully maintained.
~uneven current distribution can easily lead to skin burns or irritation.
~explain to the patient what is expected and ensure that they know to report immediately if any untoward or painful sensation are felt.
~turn the current up slowly to the required amount.
~at the end of the treatment time,ensure that the current is turned down slowly.





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About vastralphysiotherapyclinic

Physiotherapist , Samarpan Physiotherapy Clinic, Vastral, Nirant Cross Road, Ahmedabad

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