BY Azza Lotfy Ass. Lect. Of Anesthesia & ICU

LASER Light Amplification of Stimulated Emission of Radiation

Physical principles of laser Production of laser (Laser system hardware):

Physical principles of laser Characters of Laser beam : Monochromatic: one wave length) Coherent: (oscillate in the same phase) Collimated: (exist as a narrow, parallel beam)

Effect of Laser on tissues: Laser factors: Wavelength Power density Duration Tissue factors: Absorption Thermal conductivity Local circulation Scatter

Types of medical Laser: Laser mediaColorWavelength (nm) Typical application Carbon dioxideFar infrared10.600General, cutting Nd: YAGNear infrared 1.064General, coagulation KTP:YAGGreen532General, pigmented lesions ArgonGreen514Vascular, pigmented lesions Xenon fluorideUltraviolet351Cornea, angioplasty

Advantage and clinical uses of laser: Scalpel and electro coagulator. Allow precise microsurgery. Relatively dry field. Less postoperative edema and pain with lower infection rate.

Disadvantages of laser (hazard of laser) Atmospheric contamination ” laser plume” Misdirection of laser energy Gas embolism Energy transfer to an inappropriate location Fire and explosion

Disadvantages of laser (hazard of laser) Atmospheric contamination ” laser plume”: 1.Interstitial pneumonia. 2.Bronchiolitis. 3.Reduced mucociliary clearance, inflammation. 4.Emphysema. 5.Plume can be mutagenic, teratogenic or vector of viral infection.

Disadvantages of laser (hazard of laser) Misdirection of laser energy: perforation of viscous or large blood vessels. Gas embolism: Venous gas embolism when laparoscopic or hysteroscopic laser surgery are reported. Energy transfer to an inappropriate location: Eye damage (corneal opacities, retinal damage); Skin damage (from erythema to blisters or charring). Fire and explosion: Laser contact with flammable material such as rubber or plastic may cause fire and explosion.

Airway Fire Incidence; 0.5% - 1.5% Predisposing factors; 1.Flammable materials (ETT). 2.Source of ignition (Laser beam). 3.Gas support combustion (O2).

Airway Fire Fire may be: On external surface of ETT cause local thermal destruction. Blowtorch like fire.

Airway Fire Approaches to reduce the incidence of airway fire: 1.Reduction of the flammability of ETT. 2.Removal of flammable material from the airway by using : Venturi jet ventilation; Intermittent extubation with or without apnea. 3.Reduction of the available oxygen content to the minimum required for reasonable arterial saturation.

Reduction of the flammability of ETT A.The use of special type of laser resistant tracheal tube. B.Wrapped standard tubes.

Reduction of the flammability of ETT A.The use of special type of laser resistant tracheal tube; These tubes resist laser beams,more bulky, stiffer Disadvantage: Traumatic (mucosal abrasion) Reflect laser beam and transfer heat No Cuff protection Expensive

Laser resistant tracheal tube a. The Norton tube: Reusable Stainless steel Flexible tube No cuff

Laser resistant tracheal tube b.The Laser Flex tube (Mallinckrodt laser tube): Airtight stainless steel tube Flexible Uncuffed or with two cuffs

Laser resistant tracheal tube c.The Laser-Shield II (Xomed-laser shield II tube): Silicone tube Inner aluminum wrap Outer Teflon coating

Laser resistant tracheal tube d. The Bivona Fome-Cuff laser tube: Designed to solve the perforated-cuff-deflation- problem. It consists of an aluminum wrapped silicone tube with unique self inflating foam sponge filled cuff which prevent deflation after puncture.

Reduction of the flammability of ETT: B.Wrapped standard tubes: Standard tracheal tubes (rubber, silicon, and PVC). Wrapped with laser resistant material (except the cuff). the wrapped material may be :  Aluminum or copper foil tape with adhesive back.  Merocel laser guard (merocel wrap).

Disadvantage of wrapping: No cuff protection. Add thickness to the tube. Not an FDA approved device. May reflect laser beam to non target tissue. Protection varies with the type of the metal foil used. Air way obstruction. Rough edges may cause damage to mucosal surface. Wrapped standard tubes

Mechanism of wrapping: Paint the tube with medical adhesive such as benzoin. Cut the end of the tape with scalpel to approximately 60 degree. Start wrapping from the junction of the tube and the proximal end of the cuff Wrapping in spiral with 30% to 50% overlap layer. Wrapping include the inflation tube of the cuff..

Wrapped standard tubes  Protection of the cuff:  Filling the cuff with saline colored with methylene blue.  Place the cuff distally in the trachea and covered visible cuff with moistened cotton pledgets.

Approaches to reduce the incidence of airway fire: 2.Removal of flammable material from air way: a) Jet ventilation : Use high pressure oxygen source directed at the glottis through small metal tube such as ventilating bronchoscope or 12 gauge blunt needle. it permit entrainment of oxygen enriched air during inspiration and escape of carbon dioxide and exhaust gases during expiration.

Removal of flammable material from air way Advantage:  Adequate ventilation without introducing flammable material.  No obstacle to the surgical field. Disadvantage:  Barotrauma  Pneumothorax  Restriction to only anesthetic intravenous agents  Gastric distention  Relative requirement for compliant lungs

Removal of flammable material from air way b)Intermittent extubation with or without apnea:  Intermittent extubation by the surgeon.  Combined with spontaneous ventilation or intermittent apnea.  General anesthesia provided by nasal insufflations of potent inhaled anesthetic or by use of intravenous anesthetic agent.

Approaches to reduce the incidence of airway fire: 3.Reduction of the available oxygen content:  Oxygen and nitrous are powerful oxidizer.  Reduce the inspired oxygen concentration to less then  Avoiding diluting oxygen with nitrous.  Dilute with helium.

Airway fire protocol (Management of airway fire) 1.Communication and recognition. 2.Stop ventilation, remove ETT and disconnect breathing circuit from anesthesia machine to:  Remove flame  Remove the retained heat in the tube  Stop flow of enriched gas 3.Flood the surgical field with water. 4.Ventilate the patient with 100% oxygen via face mask.

Airway fire protocol (Management of airway fire) 5.Assess the damage:  Examine the patient face and oropharynx  Rigid bronchoscope.  Direct laryngoscope. 6.Monitor the patient with pulse oximetry, serial ABG and chest X ray. 7.Reintubate the patient or perform trachestomy as needed. 8.Use ventilatory support, steroid and antibiotic as needed.

Protective safety measure during laser surgery 1.Warning signs 2.Eye protection:  For the patient: eye should be taped closed and covered with opaque saline swabs or metal shield.  For the working personals: wear safety goggles or lens specific for the laser wave length in use. 3.For laser plume:  use efficient smoke evacuator at the surgical site.  Use special high efficiency mask.

Protective safety measure during laser surgery 4.Skin protection: The patient ‘skin, mucous membrane and teeth adjacent to operative field should be covered with saline soaked gauze. 5.Surgical drapes made of flame resistant or waterproof material. 6.Preventive measures against fire and explosion must be ready.

FINALLY Never are cooperation and communication between surgeon and anesthesiologist more important than during LASER surgery, it is the key to managing a crisis such as air way fire

High pressure oxygen source Venturi effect (entrainment of air). Active insipration Passive expiration