# Situation: A 66-year-old man weighing 72 kg undergoes open repair of a right inguinal hernia under spinal anesthesia. He had a right total hip replacement 5 years ago and has a healed surgical scar on the left buttock. Electrosurgery will be used. Where should the circulating nurse place the dispersive (return) electrode pad?

> source: MyMerci (mymerci.kr)  
> url: https://mymerci.kr/pages/nclex_q.php?qn_id=629770  
> language: ko  
> subject: Nursing Practice III — Care of Clients with Problems in Surgery, Oxygenation, Fluid and Electrolytes, Infectious, Inflammatory and Immunologic Response, Cellular Aberrations

## 문제

Situation: A 66-year-old man weighing 72 kg undergoes open repair of a right inguinal hernia under spinal anesthesia. He had a right total hip replacement 5 years ago and has a healed surgical scar on the left buttock.

Electrosurgery will be used. Where should the circulating nurse place the dispersive (return) electrode pad?

## 보기

1. Left anterior thigh **✔ 정답**
2. Left buttock
3. Lower back over the sacrum
4. Right lateral thigh

**정답: 1**

## 해설

The dispersive pad goes over a large, well-perfused muscle mass on clean, dry, hairless skin with full contact, away from bony prominences, scars, and metal implants. The left anterior thigh is the only site listed that meets every condition for this client.

## 심화 해설

Core principle of dispersive pad placement

Electrosurgery completes its circuit through the patient. The active electrode delivers concentrated current at the surgical site, while the dispersive electrode (return pad) collects that current over a wide surface area and carries it back to the generator. If the return pad has poor contact or is placed over tissue that cannot safely conduct current away, current density rises at that site and produces a return-electrode burn .

The pad must be placed over a large, well-perfused muscle mass so that heat generated by current flow is rapidly dissipated by blood flow. Muscle has high water and electrolyte content, making it a good conductor. Adipose tissue, bone, scar tissue, and areas with poor vascularity are poor conductors and increase resistance, which raises local temperature .

Why each option is safe or unsafe for this client

| Site | Assessment | Verdict |
| --- | --- | --- |
| Left anterior thigh | Large quadriceps muscle mass, well perfused, clean and dry, no scar or implant on that side, away from the surgical field (right inguinal area) | Correct — meets all placement criteria |
| Left buttock | Has a healed surgical scar from prior hip surgery; scar tissue is poorly vascularized and has higher impedance | Unsafe — scar increases resistance and burn risk |
| Lower back over the sacrum | Bony prominence with thin soft tissue coverage; poor muscle mass and risk of pressure-related poor contact | Unsafe — bony prominences concentrate current and impair pad contact |
| Right lateral thigh | Same side as the surgical site and near the path of current flow; also adjacent to the right hip replacement | Unsafe — proximity to the active electrode and metal implant increases risk |

The implant concern

This client has a right total hip replacement. Metal implants are conductive and can create unintended current pathways. Research using phantom models and simulations has shown that when a metallic implant lies between the active and dispersive electrodes, localized heating can occur around the implant even at routine power settings such as 20 W to 40 W . The dispersive pad should be positioned so that the current path from the active electrode to the pad does not cross through or near the metal implant. Placing the pad on the left anterior thigh directs current away from the right hip prosthesis .

Practical placement checks

Before applying the pad, the circulating nurse should confirm the skin is clean, dry, and hairless. Excessive hair should be clipped, not shaved, to avoid microabrasions that increase impedance. The pad must lie flat with full contact — no wrinkles, no gaps, and no edges lifting. It should be placed as close to the surgical site as practical while remaining on intact skin and away from the active electrode path . The pad should also be positioned away from bony prominences, scar tissue, metal implants, and areas with excess adipose tissue .

Key point! The left anterior thigh is the only listed site that provides a large, well-perfused muscle mass on clean, dry, hairless skin, with no scar, no bony prominence, and no metal implant in the current path. The right lateral thigh is too close to the surgical site and the hip prosthesis; the left buttock has a healed scar; the sacrum is a bony prominence with thin tissue .

## 임상 시나리오

Dispersive Pad Placement for ElectrosurgerySafe return electrode site selection
Place the dispersive pad over a large, well-perfused muscle mass on clean, dry, hairless skin with full contact. The left anterior thigh meets all criteria: large quadriceps muscle, no scar or implant, and away from the surgical field.

Avoid bony prominences such as the sacrum, which have thin soft tissue and poor muscle mass. Avoid scar tissue, which is poorly vascularized and has high impedance, increasing burn risk.

CautionPoor pad contact or placement over high-resistance tissue raises current density and can cause a return-electrode burn. Verify full pad contact and intact skin before activation.

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## 핵심 개념

- **dispersive electrode** — Return pad that collects electrosurgical current over a wide surface area and carries it back to the generator to complete the circuit safely
- **return-electrode burn** — Thermal injury occurring when the dispersive pad has poor contact or is placed over high-resistance tissue, causing current density to concentrate at that site
- **current density** — Amount of current per unit area; high current density at the return pad site increases local heat and burn risk
- **impedance** — Resistance to current flow; scar tissue, adipose tissue, and bone have higher impedance than well-perfused muscle
- **well-perfused muscle mass** — Tissue with rich blood flow that rapidly dissipates heat generated by electrosurgical current, making it ideal for pad placement

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