Anesthesia for LASER airway surgery Dr Ali Bandar MD, PHD 06/03/2019

Objectives ▪Definition ▪Physical principles of laser ▪Clinical application, indications & advantages ▪Types of medical LASER ▪Hazards of LASER ▪Protective safety measures ▪Anesthetic consideration

Whats is LASER? L ight A mplification by S timulated E mission of R adiation. Laser is a device that transforms light of various frequencies into a chromatic radiation in the visible, infrared, and ultraviolet regions with all the waves in phase capable of mobilizing immense heat and power when focused at close range. LASER LASER

Characteristics LASER LIGHT ▪Consists of photons-well defined very narrow band of wave lengths. ▪Monochromatic (same wavelength ) ▪Coherent (electromagnetic fields of all photons oscillate synchronously in identical phase) ▪Beams are Collimated (minimal dispersion-parallel). ORDINARY LIGHT ▪Wide spectrum of wave lengths. ▪Polychromatic ▪Electromagnetic fields phased randomly. ▪Spread out in all directions from a point of source.

Elements of a LASER 5

Clinical applications and Indications ▪Used as scalpels and electrocoagulators ▪INDICATIONS □ Benign growth ‐ nodules, polyps, cysts, granulomas □Vocal cord dysfunction □Malignant growths □Recurrent respiratory papillomatosis ▪Dermatology, Thoracic surgery, Ophthalmology, Gynecology, Plastics, ENT, Urology and Neurosurgery 6

Advantages : ▪Excellent surgical precision and preservation of normal tissues. ▪Good hemostasis. ▪Rapid healing ▪Less scar formation ▪Less postoperative edema and pain ▪Lower infection rate 7

Types of medical Laser 8

9 TypeMediumWave length Absorbing by Tissue penetration Uses CO2 LaserCO2 gas Long, 10,600 nm Invisible far infrared Water & all tissue Low Precise surgical cutting and coagulation ND-YAG laser Neodymium – Yttrium-Aluminum garnet Solid Short 1064nm Invisible Near infrared Darkly pigmented tissue Very high 2-6mm Tumor debulking Photo coagulation KTP Laser Potassium Titanyl Phosphate Short 532nm Visible Emerald green HBVery highvascular Argon LaserArgon gas Short 488nm Visible, green HB Melanin High 2-5mm Ophthalmic Dermatologic HeNe Laser Heleom & Neon gas Short 632nm Visible Red No Tissue interaction low power aiming beam for nonvisible lasers (C02andNd: YAG)

Hazards of Laser: 10 ▪Five major categories I.Atmospheric contamination II.Perforation of a vessel or structure III.Embolism IV.Inappropriate energy transfer V.Airway Fire

I. Atmospheric contamination (Laser Plume) ▪Plume of smoke and fine particulates producing because of vaporization of tissue ransported and deposited in the alveoli ▪Headaches, tearing, and nausea after inhalation ▪Animal study: interstitial pneumonia, bronchiolitis, reduced mucociliary clearance, inflammation, emphysema ▪Mutagenic and carcinogenic potential. ▪Viral infection 11

II. Perforation of a vessel or structure ▪Misdirected laser energy may perforate a viscus or a large blood vessel (cant coagulate vessel >5mm) ▪Laser-induced Pneumothorax ▪Perforation and bleeding may not occur until edema and necrosis have become maximal several days postoperatively. 12

III. Embolism ▪Gas embolism has been reported with Nd : YAG laser resection of tracheal and bronchial tumors ▪Gas embolism has been reported in laparoscopic surgery → Continuous airway CO 2 monitoring 13

IV. Inappropriate energy transfer ▪All available medical laser wavelengths are transmitted transparently through air and are well reflected by smooth metal surfaces. ▪Incidentally pressing the laser control trigger: □Tissue damage outside of surgical site □Drape fire □Eye (patient or other medical staff) □Endotracheal tube fires 14

V. Endotracheal tube fires ▪Incidence: 0.5 – 1.5 % ▪Source: □direct laser illumination □Reflected laser light □Incandescent particles of tissue blown from the surgical site 15

Blowtorch-like fire ▪Initially, fires are located on the external surface of the ETT ▪If a fire is unrecognized and burns through to the interior of the tube, the oxygen-enriched gas combined an explosive blowtorch-like fire occur and rapidly spread in a distal and proximal manner 16

Reduction of the flammability of ETT 17 A. The use of special type of laser resistant tracheal tube. Disadvantage: - Traumatic (mucosal abrasion) - Reflect laser beam - Transfer heat - Thick wall - No Cuff protection - Expensive B. Wrapped standard tubes. Disadvantage of wrapping: – No cuff protection. – Add thickness to the tube. – Not an FDA approved device. – May reflect laser beam to non target tissue. –Air way obstruction. – Rough edges may cause damage to mucosal surface.

A. Laser resistant tracheal tube AThe Norton tube: Spiral wound metal tube ▪Stainless steel connecter ▪Reusable ▪Flexible tube ▪Thick ▪Uncuffed external cuff can be attached 18

A. Laser resistant tracheal tube B The Laser Flex tube (Mallinckrodt laser tube) ▪Airtight stainless steel tube ▪Flexible ▪Uncuffed or with two cuffs 19

A. Laser resistant tracheal tube CThe Laser-Shield II (Xomed- laser) Tube ▪Silicone tube ▪Inner aluminum wrap ▪Outer Teflon coating 20

A. Laser resistant tracheal tube DThe Bivona Fome-Cuff laser tube: ▪Designed to solve the perforated- cuff-deflation problem. ▪Consists of an aluminum wrapped silicone ▪tube with unique self inflating foam sponge filled cuff which prevent deflation after puncture. 21

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). 22

B. Wrapped standard tubes 23 Type of tubeAdvantagesDisadvantages Polyvinyl chloride Inexpensive, nonreflective Low melting point, highly combustible Red rubber Puncture-resistant, maintains structure, nonreflective Highly combustible Silicone rubberNonreflective Combustible, turns to toxic ash

1. Precautions Avoiding Airway Fire A.Avoid intubation B.Laser resistant ETT C.ETT cuff should be filled with Methylene Blue D.Decrease the FIO2 E.Don’t use N2O E.Limitation Laser intensity & duration F.A source of water (60 ml syringe) should be immediately available in case of fire 24

Protocol and Management of Airway Fire: ▪The "4Es“ mnemonic 1- Elimination: Stop ventilation, Turn off 02 2-Extraction: disconnect the circuit & Remove the ETT 3- Extinguishing: If the fire persists, flood the surgical field with saline. Once the fire stops, ventilate with 100% 02 by face mask and re-intubate. 4- Evaluation: Assess airway damage 25

Protective Safety Measures: 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. 26

Protective Safety Measures: 3.For laser plume: ▪Use efficient smoke evacuator at the surgical site ▪Use special high efficiency mask. 4.Skin protection: The patient ‘skin, mucous membrane and teeth adjacent to operative field should be covered with saline soaked gauze. 27

Protective Safety Measures: 5.Surgical drapes made of flame resistant or waterproof material. 6.Preventive measures against fire and explosion must be ready. 28

Anesthetic Managment 29

Anesthetic Technique 30

Which techniques of anesthesia should be used?? 1.Non-intubation techniques 1.Intermittent Apnoec Oxygenation 2.Spontaneous Ventilation 3.Jet Ventilation 2.Intubation Techniques 31

Non-intubation techniques Intermittent Apneic ▪Advantages:  Excellent visibility  Less Airway trauma ▪Disadvantages:  Inadequate ventilation  Aspiration risk Spontaneous Ventilation ▪Advantages:  Evaluate vocal cord function  Excellent visibility  Good for compromised airway ▪Disadvantages:  Aspiration risk  Hypoventilation  Depth of anesthesia Jet Ventilation ▪Advantages:  risk of airway fire  Improved visibility  Atraumatic airway manipulation ▪Disadvantages:  Difficult to control ventilation  aspiration risk  Inability to use anesthetic gases  Barotrauma 32

Intubation Advantages ▪Secure airway, less risk of aspiration ▪Controlled ventilation ▪Administer anesthetic gases ▪Monitor O2 and EtCO2 Disadvantages ▪ETT may obstruct surgical view ▪Airway trauma ▪? Difficult Airway ▪No ETT exists which decreases risk of airway fire to zero 33

Anesthesiologist should be aware of: ▪Surgical procedure ▪Patient’s pre-existing conditions ▪Hazards of laser surgery to the patient, OR personnel and equipment ▪Laser medium and physical properties ▪Vital structures around the point of focus 34

ROLE OF ANAESTHESIOLOGISTS ▪Adequate depth of anesthesia to prevent circulatory responses to instrumentation eg; laryngoscope, operating microlaryngoscope. ▪Immobile field ▪Selection of nonflammable tube. ▪Adequate oxygenation and CO2 removal. ▪Prevention of airway fire and explosion. ▪Good post operative care. Watch for laryngospasm and laryngeal edema. ▪Immediate return of reflexes after completion of surgery ▪Scavenging of operating room gases and laser plume 35

Anesthetic plan ▪Preoperative evaluation of the airway (stridor, voice quality, ventilation pattern, flow volume loops, CT, MRI, or fiberoptic airway evaluation) ▪Mutual planning with the surgeon. ▪Aspiration prophylaxis ▪Total iv anesthesia (Propofol, Remifentanil, short acting relaxant) ▪Xylocaine spray ▪Tooth guard 36

Anesthetic plan ▪Methylene blue in ETT cuff ▪Saline gauze protection of face and airway and keep mucosal surfaces moist ▪Laser should be used in short repeated bursts (pulse), rather than in a prolonged continuous mode. ▪Communicate and monitor video camera for signs of airway fire ▪O2 < 30% using an air-oxygen mixture, avoid N2O and volatile anesthetic agents as they decompose into toxic compounds during airway fire 37

Finally: Never are cooperation and communication between surgeon and anesthesiologist more important than during head and neck surgery.” Morgan, Clinical Anesthesiology

Dr Ali Bandar: 39 Thank You