Episode 14 — Basic Principles of Surgery : Antiseptics and Disinfectants, Part 2

1️⃣ The Oxidizing Agents These agents work by releasing oxygen, which has both a chemical and a mechanical effect. *Hydrogen Peroxide (H₂O₂):* *Properties:* This is primarily a **cleansing agent**, not a true antiseptic. *Mechanism:* When it contacts tissue, it releases nascent oxygen, which creates a *frothing* action. *Uses:* 1. The frothing mechanically removes **debris from the depth of a wound**. 2. The oxygen release **destroys anaerobic organisms**. 3. It produces heat and helps control *capillary oozing* (hemostasis). It is also used to remove blood stains from clothes. *Potassium Permanganate (KMnO₄):* *Properties:* An oxidizing agent available in crystals, used in very dilute solutions (e.g., 1:5000 to 1:10000). *Uses:* Famously used as **"Condy's gargles"**—a mouthwash for stomatitis or after tonsillectomy. It is also used for urinary bladder irrigation. *Eusol® (Edinburgh University Solution):* *Composition:* Boric acid and bleaching powder (chlorinated lime). *Mechanism:* It works by *releasing nascent chlorine* and becomes useless after 24 hours. *Uses:* Its primary role is to *separate slough from infected wounds**, ulcers, bed-sores, and burns. It is acidic, making it very effective against *Pseudomonas infections. 2️⃣ Astringents, Dyes & Caustics This group of agents is used to dry, shrink, or chemically cauterize tissue. *Gentian Violet:* *Properties:* An astringent dye used in 1:100 or 1:1000 dilutions. *Mechanism:* It *coagulates serous discharge* on an oozing surface, which makes the ulcer dry. *Undesirable Effect:* It **colors the ulcer**, making it difficult to judge the progress of healing. *Acriflavine:* *Properties:* A yellow-colored crystal, used as a 0.5-2% solution. *Uses:* A mild antiseptic and astringent for ulcers with purulent discharge. It is effective on wounds with gram-negative bacteria, such as the raw area after a hemorrhoidectomy. *Mercurochrome:* *Properties:* An astringent and an inhibitor of 5-HT. *Uses:* Used for bed sore dressing. Strong solutions can damage granulation tissue. *Undesirable Effect:* Like Gentian Violet, it **stains the ulcer floor**, making it difficult to judge the progress of healing. *Silver Nitrate (AgNO₃):* *Properties:* A powerful caustic agent, stored in dark containers as it is destroyed by light. *Uses:* Applied via impregnated cotton sticks for the *chemical cauterization* of warts or *hypergranulation tissue* (proud flesh) in a wound. 3️⃣ Solvents & Irritants These agents are used to remove substances from the skin or to draw out organisms. *Ether:* *Properties:* A highly inflammable, evaporable solvent. *Uses:* Used to *clean dirty, greasy skin* by dissolving oils. It is also used as a solvent to remove the sticky zinc paste from plaster. *Turpentine IP:* *Properties:* A highly irritant mineral oil. *Uses:* 1. Used as a *solvent* to remove the zinc paste of sticking plaster. 2. In a diluted form, it is used to *bring out and kill maggots* from wounds. 4️⃣ Specialized Topical Solutions *Glycerine Magsulf Solution:* *Composition:* A saturated solution of Magnesium Sulphate (MgSO₄) crystals in sterile glycerine. *Mechanism:* This solution is **hygroscopic**. The Magnesium Sulphate acts as a semipermeable membrane, pulling fluid out of edematous tissue. *Uses:* A topical agent used to *reduce edema* in conditions like cellulitis, paraphimosis, and prolapsed thrombosed piles. *Cetavlon® (Cetrimide):* *Properties:* We mentioned Cetrimide in Part 1 as a detergent, but it has a key specialized use. *Specialized Use:* It is a powerful *scolicidal agent* used in the operation of **hydatid cysts**. A 0.5-1% solution is instilled into the cyst cavity for 5 minutes to kill the daughter cysts before being suctioned out.