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6 Cards in this Set
- Front
- Back
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Diathermy - definition |
The use of high frequency AC current (>100Khz) to create heat on patients tissues, to produce dissection or coagulation. |
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Diathermy - B/G science |
Heat is generated when current travels through resistor Heat = Current^2/Area Current density around diathermy electrode can be 10A/Cm2 - producing 200W of heat. High frequency current has low tissue penetration = doesnt cause cardiac defib |
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Diathermy Components |
Diathermy electrode Patients neutral or passive plate Diathermy case which modifys freq and voltage Isolating capacitor between patients plate and earth or floating/isolated diathermy circuit |
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Diathermy How does it work |
Patient pad - large area = low heat Isolating capacitor - low impedence to high frequency, high impedence to low frequency (cardiac shock protective) Cutting - continuous sine waveform Coagulation - modulating waveform pattern |
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How is bipolar diathermy different |
No patient plate Current flows through one tip, into tissue then out another. Bipolar is weaker and is ok for coagulation but less effective for cutting. Frequently used for neurosurgery or ophthalmic surgery |
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Diathermy Safety issues |
Patient plate area reduced = extra heat and potential for burns. If detached completely may travel between patient and earth (ie ECG leads) Electrical interference with monitoring equipment Interference with pacemakers Can cause ignition of OT fires. |
