Operating Room / Surgical Lights

Purpose

• Provide bright, shadow-free illumination over the surgical field
• Allow accurate color discrimination of tissues (differentiating arteries, veins, nerves, fat, and organs)
• Minimize heat generation on the patient and staff
• Maintain sterility around the field

Types by Lamp Technology

Mounting Configurations

1. Ceiling-mounted - Most common in ORs. Fixed or on a ceiling track. May be single or dual head. Offers the widest range of articulation (up to 56+ degrees) for aiming at the operative field.
2. Wall-mounted - Less common for surgical lights; more often used with exam lights.
3. Floor-standing / mobile - On wheels, can move between rooms. Used more for examinations than major surgeries.

Key Performance Standards

• Minimum illuminance: 40,000 lux at the surgical field
• Maximum illuminance: Up to 160,000 lux (recommended minimum capability: 100,000 lux)
• Color Rendering Index (CRI): >90 (ideally 95-100) for accurate tissue color perception
• Color Temperature: 3,500 K - 6,700 K (cool white for tissue discrimination)
• Depth of illumination: Good lighting at depth (e.g., inside a body cavity), not just at the surface

OR Lighting Zones

1. Operating table zone - Primary surgical light, highest intensity required
2. Immediate surrounding area - Reduced but sufficient illumination for scrub nurses and assistants
3. Periphery (prep and clean-up zone) - General ambient lighting for room preparation and cleaning

Key Design Features

• Shadow management: Multiple light heads arranged to eliminate shadows cast by the surgeon's hands, arms, and instruments
• Adjustable handles / sterile handles: Surgeons and scrub techs can reposition lights during a case without breaking sterility
• Heat management: Deep-red/infrared filtering to reduce tissue desiccation
• Infection control: Sealed, smooth surfaces that can be wiped down between cases
• Dimming and focus control: Adjustable beam diameter (spot vs. flood) for different procedure types
• Backup power: OR lights are on emergency circuits to prevent blackouts during surgery

Dual-Head vs. Single-Head Systems

Specialized Considerations

• Minimally invasive / endoscopic surgery: Room lights are often dimmed and surgeons rely on the endoscope's internal light source; OR lights serve a secondary role here.
• Neurosurgery / microsurgery: Require exceptionally precise illumination; sometimes supplemented with headlights or microscope-mounted light sources.
• Green LED option: Some systems (like Kenall's MedMaster) offer green LED capability, which enhances visual acuity for the surgical team under certain lighting conditions.

Carbolisation of OT (Operation Theatre) Lights

What is Carbolisation?

Why OT Lights Specifically?

• Dust and particle accumulation
• Contamination from aerosolized droplets during procedures
• Splatter from blood or body fluids

Carbolic Acid Solution Used

Step-by-Step Procedure for Carbolisation of OT Lights

• Wear gloves, mask, gown, and eye protection before handling carbolic acid - it is a corrosive chemical that can cause skin burns and mucous membrane irritation.

• No procedure should be underway. Lights should be switched off and cooled (hot bulbs can evaporate the solution and irritate airways).

• Wipe down the light shade / reflector bowl, arm, handles, and canopy with a detergent (soap-water) solution to remove gross organic matter (blood, tissue debris, dust).
• Rinse with clean water to remove detergent residue (residue inactivates phenol).

• Use a cloth or spray bottle to apply 2% carbolic acid solution evenly over:
  • Light shade/reflector
  • Light arm and joints
  • Sterile handles (especially high-touch)
  • Canopy / ceiling mount surface

• Allow the solution to remain on the surface for 10-15 minutes for effective disinfection.

• Wipe off or allow to air-dry. Ensure good ventilation to disperse fumes before the OT is re-occupied.

• Fumes from carbolic acid can be irritating - run the OT ventilation/air handling unit and ensure fumes have dissipated before any procedure.

• Record the date, time, concentration used, and name of the person who performed carbolisation in the OT log/register.

Frequency

Important Precautions for OT Lights

• Do not spray carbolic acid directly onto electrical fittings or bulbs - risk of short circuit or cracking of hot glass.
• Cool the light first - hot surfaces cause rapid evaporation of phenol, increasing fume exposure.
• LED lights - check manufacturer compatibility; some LED housings and lens coatings may be sensitive to strong phenol solutions. In such cases, 70% alcohol wipes are recommended for electronic/sensitive surfaces.
• Carbolic acid is not sporicidal - for spore-forming organisms (e.g., post-Clostridium case), glutaraldehyde or chlorine-based agents are preferred.

Modern Perspective

• Quaternary ammonium compounds for routine surface disinfection
• 0.5-1% sodium hypochlorite for blood/body fluid contamination
• Aldehyde-based fogging for terminal OT disinfection

Diathermy / Cautery Machine (Electrosurgical Unit - ESU)

Principle

Heat generated depends on: Current density, Resistance of tissue, and Duration of application.

Components of the Diathermy Machine

Monopolar vs. Bipolar Diathermy

(a) Monopolar Diathermy

• Current flows from the diathermy pencil (active electrode) → through the patient's body → exits via the large patient plate (dispersive electrode) → back to the generator
• The patient plate is large, so current density there is low - no heat generated at the plate, all heat is at the pencil tip
• Frequency: ~500 kHz; Power: up to 400 W
• Most versatile - used for general surgery, laparoscopy, TURP, etc.
• Requires a patient plate applied to a well-perfused, hair-free skin area (usually thigh/buttock)

(b) Bipolar Diathermy

• Current flows only between the two tips of the bipolar forceps - only the tissue grasped between the tips is heated
• No patient plate required
• Frequency: ~600 kHz; Power: up to 120 W
• Safer in sensitive areas - used in neurosurgery, ophthalmology, ENT, and patients with pacemakers/implantable devices
• Cannot be used for cutting - only coagulation/haemostasis

Modes of Diathermy

• Blend modes combine cutting and coagulation in varying proportions, useful for dissection with simultaneous haemostasis.

Coagulation - Direct vs. Indirect

• Direct coagulation: active electrode tip touches the bleeding point directly
• Indirect (contact/touch) coagulation: active electrode touches a metal instrument (e.g., artery forceps) which is gripping the bleeding vessel - current flows through the forceps to coagulate the vessel. The surrounding area must be dry and the forceps should hold minimal fat.

Hazards of Diathermy

1. Burns (most common)

• Faulty/improper application of patient plate (inadequate contact area)
• Patient earthed via contact with metal objects (Mayo table, stirrups, anaesthetic screen bar)
• Faulty insulation of diathermy leads
• Accidental activation of diathermy or contact with other metal instruments
• Hole in surgical glove causing finger burns
• Double-gloving helps reduce this risk

2. Channelling

• Current applied to narrow-stalked tissue concentrates ("bottleneck") and damages distant structures
• Classic examples:
  • Coagulation of the penis during circumcision in a child
  • Coagulation of the spermatic cord when electrode applied to the testis
• Prevention: use bipolar diathermy in such situations

3. Interference with Implantable Electronic Devices

• Diathermy currents can interfere with cardiac pacemakers, ICDs, cochlear implants, gastric stimulators
• Use bipolar diathermy or ultrasonic scalpel; liaise with cardiology and anaesthetics pre-operatively

4. Explosion/Fire

• Sparks can ignite alcohol-based skin prep (especially if allowed to pool), inflammable gases, or drapes
• Invisible flames possible under bright OR lights

5. Electrocution

• Rare with modern machines manufactured to high safety standards
• Requires regular expert servicing

6. Surgical Smoke - Occupational Hazard

• Diathermy smoke contains viral particles, bacteria, carcinogens, and respiratory irritants
• Use smoke evacuation systems or suction devices; universal precautions for all theatre staff

Diathermy in Laparoscopic Surgery - Special Risks

• Faulty insulation of laparoscopic instruments
• Direct coupling - contact of active electrode with another metal instrument inside the abdomen while pedal is activated
• Inadvertent pedal activation when tip is outside camera view
• Retained heat in the tip touching bowel after use
• Use insulation-testing devices and active electrode monitoring where available

Advanced Vessel-Sealing Devices

• LigaSure / Enseal - combine pressure and bipolar energy to seal vessels up to 7 mm
• Harmonic scalpel (ultrasonic) - uses ultrasonic vibration rather than electrical current; safer near nerves and implants
• Argon beam coagulator - ionised argon gas carries current for superficial coagulation of large areas (liver, spleen)

Safe Electrosurgery Checklist (Bailey & Love)

• Always check diathermy settings before use
• Use the lowest effective current setting
• Be careful when diathermy is used near other metallic instruments
• Use intermittently and for brief spells only
• Use bipolar and advanced vessel-sealing devices where appropriate
• Ensure smoke evacuation systems are in place

The Operation Table (Surgical / Operating Table)

What It Is

• Support the patient safely throughout the procedure
• Allow precise positioning for optimal surgical access
• Accommodate attachments (arm boards, stirrups, shoulder supports, etc.)
• Tilt in multiple axes (head-down, head-up, lateral)
• Interface with imaging equipment (radiolucent table top for C-arm use)

Parts / Components of the Operation Table

Types of Operation Tables

Surgical Positions on the Operation Table

1. Supine (Dorsal Recumbent) - Most Common

• Patient lies flat on back
• Used for: head, face, neck, chest, abdomen, limb surgery
• Arms placed at side or extended on arm boards (not abducted >90° - risk of brachial plexus injury)

• Ulnar, axillary, peroneal and brachial neuropraxia
• Pressure necrosis of heels, sacrum, shoulders, scalp
• Steep Trendelenburg: respiratory compromise, raised ICP, raised intraocular pressure

2. Prone Position

• Patient intubated first, then log-rolled onto the table by at least 4 team members
• Axillary and lateral chest rolls essential to allow chest movement
• Female breasts and male genitalia carefully positioned to avoid compression
• Arms placed by side of head on arm boards (care - risk of shoulder dislocation)
• Toes elevated off table by pads under shins
• Specially designed hollow face pillow accommodates face and ETT
• Used for: spinal surgery, extralevator abdominoperineal excision (rectal cancer)
• Modification: jackknife (Kraske) position - table broken at middle with head and feet hanging down; excellent perineal access

• Brachial plexus injury and shoulder dislocation
• Facial trauma; blindness secondary to vascular congestion of the eye
• Pressure necrosis of breasts, external genitalia, bony prominences
• ETT displacement

3. Lateral Position

• Patient on left or right side, stabilised with stirrups, straps, and side supports
• Lower leg slightly flexed, pillow between legs, upper leg more flexed
• Arms in stirrups; cervical alignment maintained
• Used for: perianal/pilonidal abscess drainage, lateral thoracotomy, urological/retroperitoneal procedures
• Kidney position: table "broken" (angled) at the middle with patient's flank at the summit - increases distance between costal margin and iliac crest for retroperitoneal/renal access

• Respiratory complications (preferential ventilation of dependent lung)
• Accidental endobronchial intubation migration
• Brachial plexus and ulnar nerve injury
• Corneal abrasions

4. Lithotomy and Lloyd-Davies Position

• Patient supine, legs flexed at hip and knee, placed in stirrups
• Lithotomy: hips flexed to 90°
• Lloyd-Davies: modification with hips minimally flexed to ~15° with 30° head-down tilt
• Used for: gynaecological, perineal, urological, combined abdominoperineal procedures

• Both legs placed in stirrups simultaneously (to avoid pelvic torsion injury)
• Fingers must NOT extend past the edge of the table - risk of crush injury / amputation when leg section is replaced
• Legs should not be excessively externally rotated or abducted
• Sequential compression devices useful to prevent DVT in long operations

• Venous/arterial insufficiency → limb ischaemia, compartment syndrome, DVT
• Digital amputation at table edge
• Hyperflexion → sciatic nerve damage
• Saphenous and peroneal neuropraxia

Securing the Patient - General Rules

Pre-positioning Checklist (Bailey & Love)

• Final check of the table and all accessories before patient transfer
• Optimum positioning of laparoscopic stacks, ESU, nursing trolley
• Dispersive (diathermy) leads and underbody heating blankets placed before positioning
• Consider: age, body habitus, joint mobility
• Compromise between ideal surgical position and physiologically safe position when needed
• Anaesthetist coordinates the transfer; calls the count

Objectives of Correct Surgical Positioning

1. Facilitate safe anaesthesia and surgery
2. Reduce adverse physiological insults
3. Optimise surgical exposure and ergonomics
4. Maintain the patient's dignity by avoiding unnecessary exposure